tag:blogger.com,1999:blog-55579024672887368262024-03-13T17:02:39.231-04:00AE1S Science and Engineering BlogScience, Engineering, Electronics, Amateur Radio, Nuclear PhysicsAndrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.comBlogger127125tag:blogger.com,1999:blog-5557902467288736826.post-76081046252481335222024-02-18T19:01:00.008-05:002024-02-18T21:07:06.362-05:00Lightwave portable magnetic stand for Elecraft KX3 and PX3<div style="text-align: left;"><span style="font-family: verdana;">Elecraft KX3 is a fantastic portable transceiver but one thing I thought could be improved is using a better stand to the stock, foldable legs. </span></div><div style="text-align: left;"><span style="font-family: verdana;">The built-in foldable feet are a bit annoying as they require the user to manipulate the the thumb-screws holding the radio together and because they are opposing, this needs to be done in different directions when standing in front of the radio, not to mention that the front panel sits at too low of an angle for my taste.</span></div><div style="text-align: left;"><span style="font-family: verdana;">I decided to design a lightweight stand that has small footprint and it can be assembled or taken apart in seconds in the field and will give a good support for the radio without the need to completely unfold the stock legs.</span></div><div style="text-align: left;"><span style="font-family: verdana;">It was a quick and fun half-day project.</span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcn9B_uMCOfoNb4BRuH8gKs5r9I0K_gVVZgkPytrwQT3TvOaB1qD1F1mWv76VULEEQZV203xDiEz9bWt9clcDnnhNKaI5CNfo-Qjg5ay6TlNB72fiZ1yZoMgRiFJABe6hTXzJA_IcCPM7uXoE2ipb_4QIvLDlvOH0ouAsLlXXe5x2FE3MEyP5IoYaBnkU/s2557/KX3_Stand.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1757" data-original-width="2557" height="220" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcn9B_uMCOfoNb4BRuH8gKs5r9I0K_gVVZgkPytrwQT3TvOaB1qD1F1mWv76VULEEQZV203xDiEz9bWt9clcDnnhNKaI5CNfo-Qjg5ay6TlNB72fiZ1yZoMgRiFJABe6hTXzJA_IcCPM7uXoE2ipb_4QIvLDlvOH0ouAsLlXXe5x2FE3MEyP5IoYaBnkU/s320/KX3_Stand.jpg" width="320" /></a></div><div style="text-align: center;">The two legs of the stand were designed with TinkerCad and then 3D printed.</div></span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYv1VSJxY-il0qTe4HTfk59WMcNFkblKHpTtkTaWdTUVG0jSTqfOmHkWkVLrQ-vKj3xA6epYxt6ylK7W-Xk6_aKdrL7O-K7EUgAVKTC0OM_WOnn6tLp_oo2mCwq9kKbwKrS3fDDFCgFeisd526uO9dbTWnh_2EokA4OkKft2GEIWwqJH43H_x6bMO2Mbk/s1868/20240218_155009.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1715" data-original-width="1868" height="294" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYv1VSJxY-il0qTe4HTfk59WMcNFkblKHpTtkTaWdTUVG0jSTqfOmHkWkVLrQ-vKj3xA6epYxt6ylK7W-Xk6_aKdrL7O-K7EUgAVKTC0OM_WOnn6tLp_oo2mCwq9kKbwKrS3fDDFCgFeisd526uO9dbTWnh_2EokA4OkKft2GEIWwqJH43H_x6bMO2Mbk/s320/20240218_155009.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">All of the components for the stand - the 3 spacer rods and the 2 legs. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The weight is exactly 2oz. but there is a room to shave off some of it in the next version.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1nkxhquMYVJ52XocsWa94J8tyczKS55L_etejRcPGCnAUumv9FOQXFx8G9KHtpC1xaDemg5WlOvb4YxwAPH9boGzZRBhT3IVilrtlLITF-d7E4JXFT_NVhaVtCvGGwq0wef90HKzcW8FtzasVAqqtLgDHAk6nlIAkreUwoEwt_FtLBQbu0pg25R_giG4/s2094/20240218_155122.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2094" height="285" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1nkxhquMYVJ52XocsWa94J8tyczKS55L_etejRcPGCnAUumv9FOQXFx8G9KHtpC1xaDemg5WlOvb4YxwAPH9boGzZRBhT3IVilrtlLITF-d7E4JXFT_NVhaVtCvGGwq0wef90HKzcW8FtzasVAqqtLgDHAk6nlIAkreUwoEwt_FtLBQbu0pg25R_giG4/s320/20240218_155122.jpg" width="320" /></a></div><span style="font-family: verdana;">Inside of the holes for the spacer rods, I glued small neodymium magnets. I made a "bed" for friction-fit of each magnet which has a slightly smaller diameter than the main hole, matching the inside diameter of the rod. All magnets are also glued in their "beds" in the same orientation (polarity).</span></div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOnCcHv-TXSsp-Q44HjeJVBrJ-3iKS-Lyiyzu215rCTwWPn82tXOYU3KrbZDwi6tWmT4Whm4oO5xkFJw1NIoU5SKA93Tm37kttjjnv5aw4rke2KASCDtHYFHvXMCUF1fGprAn5wDy45nmCS8wqOU-TnwHjkDv84Qfgsxm09ugxDWGVTAi8fdN8SeHRofo/s2001/20240218_155129.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2001" height="299" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOnCcHv-TXSsp-Q44HjeJVBrJ-3iKS-Lyiyzu215rCTwWPn82tXOYU3KrbZDwi6tWmT4Whm4oO5xkFJw1NIoU5SKA93Tm37kttjjnv5aw4rke2KASCDtHYFHvXMCUF1fGprAn5wDy45nmCS8wqOU-TnwHjkDv84Qfgsxm09ugxDWGVTAi8fdN8SeHRofo/s320/20240218_155129.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">For the spacer rods I used scrap cut-offs from carbon fiber arrow shafts. These are very strong and lightweight tubes and also have quite nice finish. I have a whole bunch of these pieces in varying lengths. l saved these from when I was sizing my archery arrows, knowing that one day I'll find a good use for them.</span></div><div style="text-align: center;"><span style="font-family: verdana;"> Inside each of the arrow shafts I glued the same size neodymium magnets, making sure that the polarity is the opposite of the ones in the legs.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSeTv3HvNK8o3pfBfEPo8F1FuZnlJLliOjL08ncdjmYfcEp37vXreqPuPWKCx-zrg4NSmuZ2EmGmpuNX9pHmVptjMGzo0gX83QXLLcI-WLAZENN-7GCz5I5iw_IbZ4M8aYzWf_eRZPLDo4q8_rpUAf3WbsSQJZsQJo3Gzdcgy4-vfY6od59E2u1Ff86hE/s2517/20240218_154845.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2517" height="237" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSeTv3HvNK8o3pfBfEPo8F1FuZnlJLliOjL08ncdjmYfcEp37vXreqPuPWKCx-zrg4NSmuZ2EmGmpuNX9pHmVptjMGzo0gX83QXLLcI-WLAZENN-7GCz5I5iw_IbZ4M8aYzWf_eRZPLDo4q8_rpUAf3WbsSQJZsQJo3Gzdcgy4-vfY6od59E2u1Ff86hE/s320/20240218_154845.jpg" width="320" /></a></div><br /><span style="font-family: verdana;">The stand is assembled together in seconds. The spacer rods just snap firmly in place and hold the entire stand together. Disassembling is just as easy by pulling everything apart. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The magnet-to-magnet attraction provides just the right amount of holding force without making it difficult to pull apart. </span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgG_t5Y7da4FTMsmZOuXWwMhQaVmz-XNFY47UfyUzKgbQvCXlh9XQww527KBF6tvDn4COq4IGgxpYdtfuA52WTs-8rlqpUMnozFpju7xScWDEvhmHaEEjMWmjExI-pi97DoSQM7t-M1QnAHdAHIYJmHLd4hWjcaNUrsUMmndD7ANkAwLskY-1XzZpjwmV8/s2625/20240218_155341.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2625" height="228" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgG_t5Y7da4FTMsmZOuXWwMhQaVmz-XNFY47UfyUzKgbQvCXlh9XQww527KBF6tvDn4COq4IGgxpYdtfuA52WTs-8rlqpUMnozFpju7xScWDEvhmHaEEjMWmjExI-pi97DoSQM7t-M1QnAHdAHIYJmHLd4hWjcaNUrsUMmndD7ANkAwLskY-1XzZpjwmV8/s320/20240218_155341.jpg" width="320" /></a></div><br /><span style="font-family: verdana;">The original foldable legs of the KX3 can be unfolded ever so-slightly to lock the stand in place so the radio can not move sideways. This is not really necessary as the stand's legs fit between the stock legs rubber booths but it can provide additional support if needed.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrj_WA7pWpo0wy7Evf0qYtjojd5B8_ppneRKx3t0SoaxGUlB6uYzPB9XR44n43FSiy_LEWwQorYNy3CMvR9_MEQ0G-rOCqkkvOr4qQuihXsOvYbZtLWBUkfHZLyaidbxVT4Z9kynMNozbcEw85NO9vfPLEqBVX4tNdIRLK_wf5z-VNbDIVslBq5DNbYEQ/s3179/20240218_155250.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3179" height="188" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrj_WA7pWpo0wy7Evf0qYtjojd5B8_ppneRKx3t0SoaxGUlB6uYzPB9XR44n43FSiy_LEWwQorYNy3CMvR9_MEQ0G-rOCqkkvOr4qQuihXsOvYbZtLWBUkfHZLyaidbxVT4Z9kynMNozbcEw85NO9vfPLEqBVX4tNdIRLK_wf5z-VNbDIVslBq5DNbYEQ/s320/20240218_155250.jpg" width="320" /></a></div><br /><span style="font-family: verdana;">The angle of the front panel with the radio on the stand is not as low as with the original foldable KX3 legs. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The radio sits angled at exactly 45 degrees which I find to be more ergonomic.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/U-06MxyqJSc" width="320" youtube-src-id="U-06MxyqJSc"></iframe></div><br /><span style="font-family: verdana;">Short video of one-handed assembly of my KX3 stand.</span></div><div style="text-align: center;"><span style="font-family: verdana;"> A set of shorter rods can turn this stand into a PX3 stand (the KX3's Panadapter). This stand also works great as a portable cell phone stand and I'll be making another one for use during my air travels or when using the cell phone for logging in the field.<br /></span></div><span style="font-family: verdana;"> </span></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-3347241487084224002023-12-06T06:34:00.008-05:002023-12-28T09:36:42.275-05:0013 Years later ...<p> <span style="font-family: verdana;">Today, 13 years after <a href="http://blog.kotarak.net/2010/01/one-absolutely-amazing-day.html">this post</a>, FCC issued my son's first callsign - KC1TVB. Congratulations to Vichren for passing the exam and joining the lines of the Amateur Radio Operators!</span></p><p><span style="font-family: verdana;"><b>Update:</b> Vichren applied for and got a vanity callsign - <b>N1VAS</b>. His very first DX on HF was a KH6 station in Hawaii on 10 meters using only 10W from an Elecraft KX3 into a portable Buddypole dipole, slicing thru a pileup with a 5/9 on his first call!</span></p>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-38507376356771409472023-11-03T10:40:00.035-04:002023-11-13T20:25:53.728-05:00Gamma Dog - Assisted Squelch Auto-Set (ASAS) / "Smart Squelch" System <span style="font-family: verdana;">One of the main features of the Gamma Dog project is the unique Squelch System controlling the audio output.</span><div><span style="font-family: verdana;"><br /></span><div><span style="font-family: verdana;">The Gamma Dog's Squelch System works by detecting a differential between the Natural Radiation Background <b>(NRB)</b> and the current detected rate coming from the scintillating detector. The Squelch system mutes the audio and sets a threshold level at the same rate as the NRB and when the currently detected rate exceeds this threshold level, the audio output is enabled.</span></div><div><span style="font-family: verdana;">In other words, the current rate is treated as a relative rate to a pre-set reference point (the Squelch Level) and the absolute value is insignificant for the Squelch System.</span></div><div><br /></div><div><span style="font-family: verdana;">Gamma Dog will sample the NRB rate on startup or any time when the user activates an "Auto-Set" by pressing and holding the blue Squelch button or using one the Gesture Control triggers. </span></div><div><span style="font-family: verdana;">When Auto-Set is activated, Gamma Dog will use one of 3 methods to determine the Squelch Level (the method used is selected by Menu Item #20):</span></div><div><span style="font-family: verdana;"><span> 1. Single Sample - Squelch Level will be set to the currently detected rate, using a single sample at the moment when Auto-Set is triggered.</span><br /></span></div><div><span style="font-family: verdana;"><span><span> 2. SD5 method (default) - The Gamma Dog will</span></span></span><span style="font-family: verdana;"> average the rate over the last 5 seconds, calculate the Standard Deviation and then use the upper bound of 1-sigma threshold to set the Squelch Level.</span></div><div><span style="font-family: verdana;"> 3. SD10 - same exact method as SD5 but rate is averaged over the last 10 seconds before Standard Deviation is calculated. The 1-sigma Upper Threshold is calculated by summing the average rate and SD.</span><br /></div><div><span style="font-family: verdana;"><br /></span></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgOxTinNVDdqkVW8bxiOfvbiLUPOGxoglWSB2he47e-hwefufWTaM741440ofyt2mTeZvi0IJH4ZuKSwljjXQy8f7fpEvpZi9JeFpwGKGedB1EmFfOANjHQeYthj17z9-r9wmt9iqx7twakejgPG4mevqjwv-DvynxzULWqkWHhcIFSzYGphu3BApGqV4U/s1602/Gamma_Dog_Squelch_Level.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1177" data-original-width="1602" height="235" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgOxTinNVDdqkVW8bxiOfvbiLUPOGxoglWSB2he47e-hwefufWTaM741440ofyt2mTeZvi0IJH4ZuKSwljjXQy8f7fpEvpZi9JeFpwGKGedB1EmFfOANjHQeYthj17z9-r9wmt9iqx7twakejgPG4mevqjwv-DvynxzULWqkWHhcIFSzYGphu3BApGqV4U/s320/Gamma_Dog_Squelch_Level.png" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">A critical aspect to the operation of the instrument is a properly set Squelch Level.</div><div style="text-align: center;">This makes the squelch system responsive to small fluctuations detected just above the background level.</div><div style="text-align: center;">The "sweet spot" is when the current background rate only occasionally opens up the Squelch System but not too often - up to 3-4 times per minute.</div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlJkRRIaljskITyO8DDOSG8_in13HfY_5x0Kan1S7qw7FS6mEe3qcNOKSF96Er0FiIfUHJralst_J3p7ocFzQVXxonm2GpH1OzojCr9-hyVREVMuEKrnlFSWo9EwvjjHGsNIIYWboIeTTB8GVgnSBkZuwakvxOdUlSrj4F4DWp7bhIU6-x7u6coDjkl04/s3253/Gamma_Dog_Squelch_Level2.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="3253" data-original-width="1647" height="622" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlJkRRIaljskITyO8DDOSG8_in13HfY_5x0Kan1S7qw7FS6mEe3qcNOKSF96Er0FiIfUHJralst_J3p7ocFzQVXxonm2GpH1OzojCr9-hyVREVMuEKrnlFSWo9EwvjjHGsNIIYWboIeTTB8GVgnSBkZuwakvxOdUlSrj4F4DWp7bhIU6-x7u6coDjkl04/w315-h622/Gamma_Dog_Squelch_Level2.png" width="315" /></a></div><div style="text-align: center;">The Squelch level can be Auto-Set (by sampling the Natural Radiation Background rate) or adjusted Manually, when the user is modifying the already set level with the GD Squelch Level +/- controls.</div><div style="text-align: center;">In either case, if the Squelch Level is incorrectly set against the NRB level, this could result in missing possible specimen finds or less-than-optimal Squelch functionality. </div><div style="text-align: center;"><br /></div></span></div><div><span style="font-family: verdana;">One of the problems Charles and I encountered in the field while surveying and prospecting different areas is the Squelch response to <b>highly localized Natural Radiation Background Levels</b>.</span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">For example - when surveying a REE deposit in Southern New Mexico we realized that the NRB is extremely localized - there are very well defined areas of the pegmatite exhibiting very high Natural Radiation Background ("hot zones") and just a few yards away, other areas with comparatively very low NRB ("cold zones"). This meant that we had to constantly sample the NRB rate and reset the Squelch system manually, every time we crossed over from one zone to another. On the other hand, both zones in this pegmatite produced very nice Euxenite crystals.</span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">In this situation, if we focus only on moving through the terrain without paying attention at the current squelch level, we can enter an area where the NRB rate is much lower than what the squelch is set to and any small peaks or fluctuations, possibly indicating the presence of a specimen will be masked and hidden by the squelch system (that is if the rate is not promptly re-adjusted). </span></div><div><span style="font-family: verdana;">It could be some time, before one realizes that the instrument has been quiet for too long due to a Squelch rate set too high for the current NRB Level.</span></div><div><span style="font-family: verdana;">The opposite is also true - crossing from an area with low background rate to an area with high NRB will cause the Squelch system to stay constantly open which defeats the purpose of having it in first place.</span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;"><b>To resolve this issue, we came up with the "Smart Squelch" System or Assisted Squelch Auto-Set </b></span><b style="font-family: verdana;">(ASAS</b><b style="font-family: verdana;">).</b></div><div><span style="font-family: verdana;"><b><br /></b></span></div><div><span style="font-family: verdana;">The purpose of ASAS is to constantly monitor the current rate, compare it to the state of the Squelch System and detect conditions which can indicate that the Squelch rate might be incorrectly set for the current background. </span></div><div><span style="font-family: verdana;">Once ASAS determines that the Squelch Level needs an adjustment, it will trigger an Auto-Set action, same as if the user pressed the Auto-Set button and it will re-sample the NRB.</span></div><div><span style="font-family: verdana;">This allows for very easy, smooth and worry-free operation - ASAS System does all of the necessary adjustments when they are needed, and the user can focus on the terrain and not on the instrument. </span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;"><i>The implementation of ASAS is different between the one I designed, and the one Charles is using in his GD version. The main difference is that in my version, due to the availability of display, menu system and persistent configuration parameters, I can configure many internal aspects of the ASAS behavior and make it </i></span><i style="font-family: verdana;">customizable and </i><i style="font-family: verdana;">more flexible.</i></div><div><span style="font-family: verdana;"><i><br /></i></span></div><div><span style="font-family: verdana;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjodYMOV6a1Xn2o_ODKS7idXlXCpUj7P-rNkl9KacVWszdPgyNJmYZO3dBSUNpqYrZ9cEsDZvlyLU7RUe-abUCSq8HCG53shaftTxhIz9XxAhRq3g7d6vwFki-LiStmAldq__eb_br8Y5KVyJ-p2SLPBpNNDncryFj_PbiK3zh1JtfJ3LVBLuPE5kwQNF0/s2941/Gamma_Dog_Squelch_Level3.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2941" data-original-width="1903" height="567" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjodYMOV6a1Xn2o_ODKS7idXlXCpUj7P-rNkl9KacVWszdPgyNJmYZO3dBSUNpqYrZ9cEsDZvlyLU7RUe-abUCSq8HCG53shaftTxhIz9XxAhRq3g7d6vwFki-LiStmAldq__eb_br8Y5KVyJ-p2SLPBpNNDncryFj_PbiK3zh1JtfJ3LVBLuPE5kwQNF0/w367-h567/Gamma_Dog_Squelch_Level3.png" width="367" /></a></div><div style="text-align: center;">This is how ASAS monitors the state of the Squelch System.</div><div style="text-align: center;">Out of the 19 Configuration Menu Items, there are 4 menu items dedicated to the ASAS system.</div></span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">In my implementation, there are 2 separate timers configured with a single menu item, setting the period for a condition to be present continuously, before an Auto-Set is triggered.</span></div><div><span style="font-family: verdana;">One timer is reset every time the Squelch is Open, while the other timer is reset every time the Squelch is closed. Basically, I monitor the state of the Squelch System and cross-reference the state with the currently detected rate.</span></div><div><span style="font-family: verdana;">The timers can be set for 15, 30, 45 or 60 seconds.</span></div><div><span style="font-family: verdana;"><br /></span></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfFGngEyBncm6lIjMUrKEv38qexaAogHfOPWS_-TpFxpeR3U0MU-gyPcL0k1hSInJwiLtP7Q0rlNxdpXVAIWkqxWWf9gXkDsTtUxSk-E8ubR_z_msx7W8xzGvbhXden6HRq8SsR28TIV8iwMsW8hRLM5mtxjvIK_Jy9he6vrc7gpWI4rRktjcl9qd6flU/s2941/Gamma_Dog_Squelch_Level4.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2941" data-original-width="1903" height="557" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfFGngEyBncm6lIjMUrKEv38qexaAogHfOPWS_-TpFxpeR3U0MU-gyPcL0k1hSInJwiLtP7Q0rlNxdpXVAIWkqxWWf9gXkDsTtUxSk-E8ubR_z_msx7W8xzGvbhXden6HRq8SsR28TIV8iwMsW8hRLM5mtxjvIK_Jy9he6vrc7gpWI4rRktjcl9qd6flU/w360-h557/Gamma_Dog_Squelch_Level4.png" width="360" /></a></div><span style="font-family: verdana;">One functionality I added to ASAS is the ability to "decide" if Squelch Auto-Set is needed while the squelch has been open for a long time.</span></div><div><span style="font-family: verdana;">When the user needs to pinpoint the location of a specimen, it often helps for the squelch to stay open so variations in the pitch of the audio tone can be monitored closely and in this case Auto-Set should not be triggered.</span></div><div><span style="font-family: verdana;">In my implementation of ASAS, I have a menu item which specifies a second, virtual threshold level which, when exceeded, it will prevent the Auto-Set from activating due to continuously open squelch by resetting the Open Squelch Timer.</span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">The logic behind this is that if a specimen is found and the user is now trying to localize it, the detected rate will be vastly higher than the NRB / Squelch Rate and not just slightly above it - the ASAS system will identify this large difference in rates and it will not trigger an Auto-Set, thus allowing the user to listen to the audio tone. </span></div><div><span style="font-family: verdana;">The ASAS Reset Lvl, determines the height of the virtual "localization rate" as a percent of the current rate above the squelch rate. This value can be configured as 37%, 50%, 62%, 75%, 100% and 150%.</span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">For example - if ASAS Reset Lvl is set to 100%, the Squelch Rate is set to 200 CPS and the detector reports a current rate of >400 CPS (or exceeding the Squelch rate by more than 100%, ASAS will not trigger an Auto-Set assuming the user has found a specimen and just tries to pinpoint it. If the rate drops below 400CPS then the continuously open squelch condition will trigger an Auto-Set when the timer for it expires.</span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">Another functionality in my ASAS System is adding a "padding" (called ASAS Tolerance) between Squelch level and current rate while the squelch is monitored for continuously closed condition. The amount of padding or tolerance is adjustable with a menu item (ASql Toler) and specifies </span><span style="font-family: verdana;">in CPS</span><span style="font-family: verdana;"> how low the current detected rate must drop below the Squelch Level before the timer of the continuously closed squelch activates an Auto-Set action.</span></div><div><span style="font-family: verdana;">This differential can be set from just below the current Squelch Level to a few hundred CPS lower and it is intended to add adjustable damper for the response to constantly closed squelch.</span></div><div><span style="font-family: verdana;">The options are 100 CPS, 150 CPS, 200 CPS, 250 CPS and 500 CPS</span></div><div><br /></div><div><span style="font-family: verdana;">By default, the ASAS System is deactivated and can be toggled ON/OFF by double-clicking the GREEN Button.</span></div><div><span style="font-family: verdana;">The last menu item of the ASAS System configures whether the system is activated automatically at the startup of the instrument, or the user activates it at a later time.</span></div><div><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/cu1_gGNHVhI" width="320" youtube-src-id="cu1_gGNHVhI"></iframe></div><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;">The ASAS System in action. </span></div><div style="text-align: center;"><span style="font-family: verdana;">When the ASAS is active, the "Sql" indicator above the Squelch Level is replaced with "(A)". The timeout is set to 15 seconds in this demonstration.</span></div><div style="text-align: center;"><span style="font-family: verdana;">The two bars on the display shrink, while showing when a timer is about to expire - the top bar is for Open Squelch conditions and the bottom bar is for Closed Squelch conditions. A full width bar represents the maximum time and dot is displayed for the trigger point.</span></div><div style="text-align: center;"><br /></div></div><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/oZ2lkrFl7OE" width="320" youtube-src-id="oZ2lkrFl7OE"></iframe></div><br /><div style="text-align: center;"><span style="font-family: verdana;">Charles searching for REE in Petaca, NM while using the "Smart Squelch" System.</span></div><div style="text-align: center;"><span style="font-family: verdana;">The Gamma Dog produces distinctive beeps every time when the Automatic Squelch System is triggered to re-sample the Squelch level.</span></div><div style="text-align: center;"><br /></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-33651117741211370702023-09-05T12:00:00.017-04:002023-09-08T10:02:27.552-04:00Pulse Height Analyzer (PHA) option for Eberline ASP-1<p><span style="font-family: verdana;"> When it comes to those big, beige, analog metering system, heavy metal and clunky radiation detectors from the 80s... I am a huge fan of ... not Ludlum Model 3 but the Eberline ASP-1. I have 3 such units and they are really versatile! </span></p><p><span style="font-family: verdana;">For anyone interested I made a brief review and comparison between <a href="https://www.reddit.com/r/Radioactive_Rocks/comments/kw231f/eberline_asp1_vs_ludlum_model_3_is_eberline_asp1/">Ludlum Model 3 and ASP-1</a>.</span></p><p><span style="font-family: verdana;">Eberline ASP-1 was and still is a fantastic meter for its time! In the name "Analog Smart Portable" (ASP), the "Smart" stands for "Microcontroller" - an 8-bit Intel 80C31 is in the heart of the meter, driving an 8-bit DAC (AD7524) which on the other hand drives the Analog Metering System. Two old-school 74HC157 multiplexers read the state of various config DIP-switches and the main rotary Range switch.</span></p><p><span style="font-family: verdana;">Reviewing the Service Manual for the meter years ago, I noticed that Eberline designed a Pulse Height Analyzer (PHA) module for it but for all these years I was never able to find, or even see a picture of one in existence. I am not even sure if this option was ever manufactured / sold for ASP-1 but I have seen dozens of ASP-1 units and not a single one had this module installed.</span></p><p><span style="font-family: verdana;">The Pulse Height Analyzer allows the meter to count pulses only when they have a specific energy range (of course, when the meter is equipped with an energy discriminating detector (scintillator)).</span></p><p><span style="font-family: verdana;">The PHA creates a "window" which has an adjustable width and can also be moved up and down the energy range so the counter can count only pulses produced due to gamma rays from a specific isotope - for example it can count only Cs-137 gamma at 662keV while ignoring any other energies, making it very selective at what activity is measured.</span></p><p><span style="font-family: verdana;">From a practical point, I can set it up for a specific U or Th decay chain isotope and being able to differentiate in the field if I am dealing with U or Th for example (that is if I don't have my Raysid with me)</span></p><p><span style="font-family: verdana;">The PHA module is interfaced via a "PHA Option" socket on the main board of ASP-1. This socket must be populated with a special shorting connector when the PHA Option is not installed and so was the case with all of my 3 ASP-1 units, until now...</span></p><p><span style="font-family: verdana;">After I was unable to procure the ASP-1 PHA Option for years, I got tired of looking for it and decided to make my own modules.</span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtihi-bVxYfJ7K9xhrndScmldfNgeKzxvplXByrWdbILyaldIIKx2rUCCue1uvpCtI14qmoSSzhmfaOAn9KG9wyDbfaza-V2zBosQVvpvbUEUl5ztHVKdmqDBYfaTyDUKZROptlRzXniWkgZZpD6r8B8Hjm9O3TRmrLrzQ213gegVG8j_SDQ5_dOgqq0w/s1968/20230905_095245.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1968" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtihi-bVxYfJ7K9xhrndScmldfNgeKzxvplXByrWdbILyaldIIKx2rUCCue1uvpCtI14qmoSSzhmfaOAn9KG9wyDbfaza-V2zBosQVvpvbUEUl5ztHVKdmqDBYfaTyDUKZROptlRzXniWkgZZpD6r8B8Hjm9O3TRmrLrzQ213gegVG8j_SDQ5_dOgqq0w/s320/20230905_095245.jpg" width="304" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">The PHA Option socket with the Shorting Connector removed.</div></span><span style="font-family: verdana;"><br /></span><p></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg95_rfFqMSyHqbfrJHwyDYEMvpSJYAQZmUI3Y9C5UYaF4-bNoJThkeSZC8hi-ROKgwjXbjlU16Sg65N6fR0QvNGsptcSFaCtZjkPKH44b9gAmh09eAtxLoXWoUEQireE38gZbIyJaC1hAzgjQWphGHW0_juFr4-o6az0Nb6QFl9jlUfNDk4gjX1xHkSJc/s2035/ESP-1.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1469" data-original-width="2035" height="231" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg95_rfFqMSyHqbfrJHwyDYEMvpSJYAQZmUI3Y9C5UYaF4-bNoJThkeSZC8hi-ROKgwjXbjlU16Sg65N6fR0QvNGsptcSFaCtZjkPKH44b9gAmh09eAtxLoXWoUEQireE38gZbIyJaC1hAzgjQWphGHW0_juFr4-o6az0Nb6QFl9jlUfNDk4gjX1xHkSJc/s320/ESP-1.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">The same PHA Option but for a different meter - the Eberline ESP-2. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The schematics are virtually identical - only board outline and component topology appear to be different from the one, specific to ASP-1.</span></div><p><span style="font-family: verdana;">Fortunately, the Service Manual includes full documentation and schematics for this board.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4hwisM6pWufxRPUc_AqbPCBPnKJ4DMWrO3lsJA5_A4YiMBk8Kbcp4JwCyMveu78leYZhGmqNNVNOYTZnjKVSLbqw8akMYZIrzRyht5zBjzhjUsmcsAZ_WlZFblKJTV0nG72k_mYLBNN5RaTZnuwI5IqhEaTENHUYVROWfM33bjMo0wSaFldjILDSZK2Y/s2556/PHA_EBERLINE.JPG" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1000" data-original-width="2556" height="125" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4hwisM6pWufxRPUc_AqbPCBPnKJ4DMWrO3lsJA5_A4YiMBk8Kbcp4JwCyMveu78leYZhGmqNNVNOYTZnjKVSLbqw8akMYZIrzRyht5zBjzhjUsmcsAZ_WlZFblKJTV0nG72k_mYLBNN5RaTZnuwI5IqhEaTENHUYVROWfM33bjMo0wSaFldjILDSZK2Y/s320/PHA_EBERLINE.JPG" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">This is the schematics for the PHA board published in the Eberline ASP-1 technical manual.</span></div><div style="text-align: center;"><span style="font-family: verdana;">There are no exotic components and everything for this circuit is readily available on DigiKey. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The circuit itself is fairly simple, using comparators and voltage dividers for reference to determine the energy "window". There is also a Dual BCD up-counter alongside a bunch of other passive components. </span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDwikAl0LNuvLLSqWVofRs6z5ER_DjdUQXtv0ib2unA_f1TSPCLzzSkar8pLgaJg4L6iu1r_FjTD_KPRe8Fo1Fe3Vhya6seDtP3FOqXSWzWBcLGFLpHR-A2ZRxEv_tnQTdNfHCEdxfPIm7Q708snbu4a8jwte9WOICgTXifTbh-K17yq0rTp9Sdby7HE8/s1370/outline_PHA.JPG" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1365" data-original-width="1370" height="319" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDwikAl0LNuvLLSqWVofRs6z5ER_DjdUQXtv0ib2unA_f1TSPCLzzSkar8pLgaJg4L6iu1r_FjTD_KPRe8Fo1Fe3Vhya6seDtP3FOqXSWzWBcLGFLpHR-A2ZRxEv_tnQTdNfHCEdxfPIm7Q708snbu4a8jwte9WOICgTXifTbh-K17yq0rTp9Sdby7HE8/s320/outline_PHA.JPG" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">The board outline is very specific as this board needs to fit between existing connectors and components located on the top side of the main board. </div><div style="text-align: center;">The R32 Trimmer-potentiometer controls the width of the energy "window", and the slide switch allows to turn off PHA counting mode and to GROSS count all pulses. </div></span><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlgKZqR2Tjjk1pGNR64FdgU55FKyZ9Q4Q-JRGO3rNkc7_J399ypkSaS0NUjRYg9efO_4zpgmxCSQitsk12hzBvketJYAcazr5nXQZgKn-gIT9X1Bppaj-DR67YIqIDbIyjJ_I2hwi0Y5wUi_y81DvxrOH4b9gos9FjZtd0oGGVuMz9Po6Nwqd4_ts-49o/s5679/PHA.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="3204" data-original-width="5679" height="181" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlgKZqR2Tjjk1pGNR64FdgU55FKyZ9Q4Q-JRGO3rNkc7_J399ypkSaS0NUjRYg9efO_4zpgmxCSQitsk12hzBvketJYAcazr5nXQZgKn-gIT9X1Bppaj-DR67YIqIDbIyjJ_I2hwi0Y5wUi_y81DvxrOH4b9gos9FjZtd0oGGVuMz9Po6Nwqd4_ts-49o/s320/PHA.png" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">I started by re-creating the schematics in AutoCAD Eagle.</div></span><p></p><p style="text-align: center;"><span style="font-family: verdana;"> I decided to keep the old-school DIP-14/DIP-16 versions for the ICs but replaced all other components with their SMD versions, using 1206 footprint for quick and easy soldering. </span></p><p style="text-align: center;"><span style="font-family: verdana;">Since it is a fixed size board there was no gain of going SMD for the ICs and their SMD versions were actually more expensive. </span></p><p style="text-align: center;"><span style="font-family: verdana;">I kept the original component names as listed in the technical manual - this makes component installation and troubleshooting very easy.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-ftiRkWeK_E1POCgPVdgoZ2XxlPq0vSO3kY_qZdOSxPv9dksBWMzY0K2Bk0OVLUfBvq3lWAXui6oK7RNQ6q-1yBjrAHF15XxhObSAYMXr6A7AL8_VoAq8rvSRnjR0wVt_8Uj_WmpEFxfHaF0_dS6SkDCfqryf-0xO-nBjjHpVm07CxscfBbrrtcCsLmo/s1805/Top_Layer_PHA.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1322" data-original-width="1805" height="234" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-ftiRkWeK_E1POCgPVdgoZ2XxlPq0vSO3kY_qZdOSxPv9dksBWMzY0K2Bk0OVLUfBvq3lWAXui6oK7RNQ6q-1yBjrAHF15XxhObSAYMXr6A7AL8_VoAq8rvSRnjR0wVt_8Uj_WmpEFxfHaF0_dS6SkDCfqryf-0xO-nBjjHpVm07CxscfBbrrtcCsLmo/s320/Top_Layer_PHA.png" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">The PCB Layout created in AutoCAD Eagle.</div></span><div><div style="text-align: center;"><span style="font-family: verdana;">Because of the location of the board, right behind the analog metering system, I realized that this board can also conveniently host LED backlighting for the metering system (the stock backlighting uses 2 incandescent light bulbs). </span></div><div style="text-align: center;"><span style="font-family: verdana;">I utilized the unused pin 2 on the Option header to provide the switched ground to the LED lighting and a small modification of the main board ties Pin 2 to the light switch. The LED Anodes are connected by jumper wire to the +VBAT</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiiQKY6rTrCKBnIuwp9l0v2PoPhSnzv3LwOXAMScFd0KG14AdCVV20UqVQ1emQBaMfpYntUNauNzYpyRlJ4OFBVC557DQ932JBf61MWkWzH3GD_2NzIa54Q8Ub-gVthaS0_eBclKQLnqvTHSwyMNbNA6GQWfsdK2joBkS4hzNQ_Lqko_Mte1oTvnX7lfw/s2591/20230823_093412.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2591" height="231" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiiQKY6rTrCKBnIuwp9l0v2PoPhSnzv3LwOXAMScFd0KG14AdCVV20UqVQ1emQBaMfpYntUNauNzYpyRlJ4OFBVC557DQ932JBf61MWkWzH3GD_2NzIa54Q8Ub-gVthaS0_eBclKQLnqvTHSwyMNbNA6GQWfsdK2joBkS4hzNQ_Lqko_Mte1oTvnX7lfw/s320/20230823_093412.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">Top Layer of the completed PHA Option Board. Some additional milling of the board outline was needed to make it fit between the components.</span></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZBSRIUkumGVheMxe70pB2spo-IezYUU3kTgb9-owy6VwtUm4XF4aOIyhMmu6vmRrFfrFY2nHTYbHpTpoxbYZi9mgeavHZ8vvO-7m61NRu8nMtI7ZlekfXK7lBUBrUm84iLDYgbj-f6MLdVb2tUQjLt9OMvRgxT7KLuU5Y1WxSZPcft4kWM_lVkpNH08g/s2596/20230823_093527.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2596" height="230" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZBSRIUkumGVheMxe70pB2spo-IezYUU3kTgb9-owy6VwtUm4XF4aOIyhMmu6vmRrFfrFY2nHTYbHpTpoxbYZi9mgeavHZ8vvO-7m61NRu8nMtI7ZlekfXK7lBUBrUm84iLDYgbj-f6MLdVb2tUQjLt9OMvRgxT7KLuU5Y1WxSZPcft4kWM_lVkpNH08g/s320/20230823_093527.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">Bottom PCB layer with the male DIP-16 header for interface with ASP-1</div></span><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjm9HqLUk7pICsZ0jTs0P-XzdWyyuLYc191t2-ZblB0NVbpzlR_m-dxCJLATrQERc-pnmtVo5PHPUATBOcchccFP2Q-ir1wThGNVtSyL1FF3vaG-ON8eQ9MIvALbEa2e1hStiTLlfV0DIWZHlvtDrVW46DRjY7e7xkbj89vVjxIovFORawrQKUyXz3XAbk/s2405/20230905_095756.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2405" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjm9HqLUk7pICsZ0jTs0P-XzdWyyuLYc191t2-ZblB0NVbpzlR_m-dxCJLATrQERc-pnmtVo5PHPUATBOcchccFP2Q-ir1wThGNVtSyL1FF3vaG-ON8eQ9MIvALbEa2e1hStiTLlfV0DIWZHlvtDrVW46DRjY7e7xkbj89vVjxIovFORawrQKUyXz3XAbk/s320/20230905_095756.jpg" width="249" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The PHA Board installed in the Option socket. The Blue Pot is the "Window" trimmer, and the red slide switch changes the mode between "GROSS" and "PHA" counting.</span></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXOKoBaL2Vz6U4fWjIoesDsQsSg1NzaWekDmzA4dCOaJlxgJZ0jlG9rfAoapQWEk-929M_5PyKvcLxMRFsN8-1cqxfBuug97iFSVGJJF7dTcg7YqbE0flLfdjUQutqIP4CL1OD0pJT4ghwkFuoda1lC_7SPPAefdiIsSxqRSzZrfCYc9iB98jVjUJYKqc/s3571/20230905_095849.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3571" height="167" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXOKoBaL2Vz6U4fWjIoesDsQsSg1NzaWekDmzA4dCOaJlxgJZ0jlG9rfAoapQWEk-929M_5PyKvcLxMRFsN8-1cqxfBuug97iFSVGJJF7dTcg7YqbE0flLfdjUQutqIP4CL1OD0pJT4ghwkFuoda1lC_7SPPAefdiIsSxqRSzZrfCYc9iB98jVjUJYKqc/s320/20230905_095849.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">The PHA Option board sits nicely behind the Analog Metering System.</span></div></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;"><b>I have 3 completed PHA Option for ASP-1 modules left, available for purchase at $50</b></span><b style="font-family: verdana;">/each</b><b style="font-family: verdana;"> + shipping.</b></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-6205117228325059142023-07-15T17:46:00.024-04:002023-09-22T08:51:07.826-04:00Gamma Dog hardware - PCB v4.0<p><span style="font-family: verdana;">I finished the design of PCB v4.0 for the Gamma Dog and OSH Park service came through again with excellent manufacturing quality boards.</span></p><p><span style="font-family: verdana;">The improvements in the schematics and layout are not huge but this version incorporates the progress in the development, which continued after PCB v3.0.</span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6843lqIA0PgCprOBm5M2htYDPGnEAtu8-siU9Sipo9XVC6BguYkZ_6k8ess3XR7S3Mzg8bVYpf_klqTP_PVosK1v_sBDf2pfjoEBd1FDndTncdryZFHG0Q743PzFYoOZa3UUskdBgQcJp797YvVt5hqe79AChS9m78zxvrL7QuUS0zFLpcvympM3ke0o/s1821/20230728_094313.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1821" data-original-width="1820" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6843lqIA0PgCprOBm5M2htYDPGnEAtu8-siU9Sipo9XVC6BguYkZ_6k8ess3XR7S3Mzg8bVYpf_klqTP_PVosK1v_sBDf2pfjoEBd1FDndTncdryZFHG0Q743PzFYoOZa3UUskdBgQcJp797YvVt5hqe79AChS9m78zxvrL7QuUS0zFLpcvympM3ke0o/s320/20230728_094313.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">Gamma Dog Main PCB v4.0</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3_MDw-3INnhlzzgmFThNLlQjNPcDVkI-l18G6JbfvlitdfIEeyXWx-nOhioWgIVajpKBnTVM_XeGtJYXSy1wuSNIuK2O4NxFM_Vt4ILMfpBDPXoGp4iSu9nKMuCwN4qF2XC7HS16G-jD-BhMjIhZAeUtoGxN0IRuyFNNnuhXUxdrY1wkW3rrNWyzgzKo/s1439/20230728_093923%20-%20Copy.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1439" data-original-width="1163" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3_MDw-3INnhlzzgmFThNLlQjNPcDVkI-l18G6JbfvlitdfIEeyXWx-nOhioWgIVajpKBnTVM_XeGtJYXSy1wuSNIuK2O4NxFM_Vt4ILMfpBDPXoGp4iSu9nKMuCwN4qF2XC7HS16G-jD-BhMjIhZAeUtoGxN0IRuyFNNnuhXUxdrY1wkW3rrNWyzgzKo/s320/20230728_093923%20-%20Copy.jpg" width="259" /></a></div><span style="font-family: verdana;">Bottom layer with a Marie Curie quote.</span><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><br /></div><div style="text-align: left;"><span style="font-family: verdana;"><b>Changes from PCB version 3.0:</b></span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><ul style="text-align: left;"><li><span style="font-family: verdana;">changed the placement of the DAC board and EEPROM board connectors. The new version of the 12-bit DAC daughterboard is slightly larger due to additional QT connectors and it wouldn't fit in the old footprint. </span></li></ul><ul style="text-align: left;"><li><span style="font-family: verdana;">added HV voltmeter circuitry for measuring and adjusting the HV PMT Bias in the field - the measurement range is 0 - 1255V (max). The High-Voltage reading is displayed when entering the menu system's diagnostic screen and will allow for field adjustments when changing different detectors. The circuit provides HV PS status data for the Self-Diagnostics / Health-Check during startup. The accuracy is better than the on-screen resolution of 1V.</span></li></ul><ul style="text-align: left;"><li><span style="font-family: verdana;">added the I2C digital potentiometer for the Digital Audio Volume Control to the main board (MSOP-10 package) - with the previous version it was an in-line add-on board as it was developed after fabrication of PCB v3.0</span></li></ul><ul style="text-align: left;"><li><span style="font-family: verdana;">added support for the LED in the GREEN/DOWN button - this LED serves as "Charging" (flashing) and "Charge complete!" (solid) indicator during battery charging.</span></li></ul><ul style="text-align: left;"><li><span style="font-family: verdana;">added an SMD jumper to configure the power source for the Audio Power Amplifier module - options now are either regulated 3.3V from the MCU board or direct battery power (4.1V max) (affording the highest possible audio volume).</span></li></ul><ul style="text-align: left;"><li><span style="font-family: verdana;">re-organized (separated) and moved the DOWN Button and Audio Amplifier connectors - the GREEN/DOWN button now has a dedicated 3-pin connector (previously, shared it with the Audio Power Amplifier), and the connector is placed closer to the button's location.</span></li></ul><ul style="text-align: left;"><li><span style="font-family: verdana;">removed all of the unnecessary component footprints, related to the old analog circuit for setting Minimum Pulse Height Threshold.</span></li></ul><ul style="text-align: left;"><li><span style="font-family: verdana;">Improved the matching between the motherboard's pads and the corresponding HV PS module output and GND pads for easier installation of the piggybacked PS module.</span></li></ul><ul style="text-align: left;"><li><span style="font-family: verdana;">Various small changes in component placement, trace routing and overall layout optimizations.</span></li></ul><div><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhV42x_PFHPdNHr8r1Mf_MdVT8rZ3FhOAi8Xo8gpwZclexidudx4VEzXJ50APA7SWbzETJ0laW2qMkxjUSR0MF1fEZ2WNyXWisVWZ1de_AWcIFvgeUHTbUoHN-hU8Xc8B0lkShLdUkF7_NvGGSpm7aSG6Qs5ZzceFnirad4Knbe96VFARb5CmW_cei1t5Q/s1888/20230828_105935.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1888" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhV42x_PFHPdNHr8r1Mf_MdVT8rZ3FhOAi8Xo8gpwZclexidudx4VEzXJ50APA7SWbzETJ0laW2qMkxjUSR0MF1fEZ2WNyXWisVWZ1de_AWcIFvgeUHTbUoHN-hU8Xc8B0lkShLdUkF7_NvGGSpm7aSG6Qs5ZzceFnirad4Knbe96VFARb5CmW_cei1t5Q/s320/20230828_105935.jpg" width="317" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">The PCB with SMDs, sockets, headers and connectors installed. Visible on the right is the HV voltmeter's VD string of precision resistors. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The input impedance of the voltmeter is >1 GOhm to reduce any voltage drop caused by the measurement circuit.</span></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTgDDP939z1UQbaLph9ObrN9yLGLicejgkV6RtHVD1oNlicSKOM4Vmin1jxEqROOH2g7ob1f9b38D6dC_1vHS9HZbtyn2xIdVIGhrs6Ypt3HhsvOtNJpYAvFXq7EsyA40S_d0NJxy3bXACl2H_EgJIbrbpD4_XJ3AjskdDC_JllcUxEaqCASalMkoOJ7g/s1867/20230828_120231.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1867" data-original-width="1845" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTgDDP939z1UQbaLph9ObrN9yLGLicejgkV6RtHVD1oNlicSKOM4Vmin1jxEqROOH2g7ob1f9b38D6dC_1vHS9HZbtyn2xIdVIGhrs6Ypt3HhsvOtNJpYAvFXq7EsyA40S_d0NJxy3bXACl2H_EgJIbrbpD4_XJ3AjskdDC_JllcUxEaqCASalMkoOJ7g/s320/20230828_120231.jpg" width="316" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">DAC, EEPROM, Comparator and HV Power Supply + Pulse Amplifier </span></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEht66CPuxelKuIWRjtIEtrZKZBLrjIssIc53Wlw9uG-jdn9LsL0_khnVivUXQJdoXK49-4GLxnPcBTq0OMlU2n-GCLJ4DTQ956dDU-8687Iyaa09MOUEQ9EoSRF-jN84ieyNlGlojGiZLbE0iofM-6Nj27ev88Ky7HGduDhtdIZIwGwFdxf7QAsQadZJAA/s1841/20230828_131551.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1825" data-original-width="1841" height="317" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEht66CPuxelKuIWRjtIEtrZKZBLrjIssIc53Wlw9uG-jdn9LsL0_khnVivUXQJdoXK49-4GLxnPcBTq0OMlU2n-GCLJ4DTQ956dDU-8687Iyaa09MOUEQ9EoSRF-jN84ieyNlGlojGiZLbE0iofM-6Nj27ev88Ky7HGduDhtdIZIwGwFdxf7QAsQadZJAA/s320/20230828_131551.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">The nRF52840 MCU module along with various sensors and RFI Shielding Can around the HV circuit</span></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSev-FmJ-jTt09E78pxkT1bqOE1E-NTk-_NQwqsTs8Rx25YU2RBFGm8IdCLMv2jn9Wc6QhN0KEYxcuB__wf7JHjmuPeiCtWcBmvtkLCwRFw81emvmfn5wEiZ-KpAZpt2GV0Pao_AEwjeikxqeHUPtrzTMDMiU2jIg6hm79laU1ZZp62a2OER-T3YzrbxI/s1561/20230828_194648.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1561" data-original-width="1546" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSev-FmJ-jTt09E78pxkT1bqOE1E-NTk-_NQwqsTs8Rx25YU2RBFGm8IdCLMv2jn9Wc6QhN0KEYxcuB__wf7JHjmuPeiCtWcBmvtkLCwRFw81emvmfn5wEiZ-KpAZpt2GV0Pao_AEwjeikxqeHUPtrzTMDMiU2jIg6hm79laU1ZZp62a2OER-T3YzrbxI/s320/20230828_194648.jpg" width="317" /></a></div><span style="font-family: verdana;">Latching Relay module and RFI shielding cover installed.<br /></span><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsTeti-103o_CVaPXT3sINSwCsLYlMIuhdE1B9-qK_XDc98vmJZ7Cvcz9YsrRT1hl1abN9BPdTaYHu5mx-4adGxOo7X9OS7rMXRH6_oOPO-3ONH_S333GhEEysj2zgSI4WDeD1BAT5sI259sZNMQWiSA9weQnkCgF-zyd9C_d3BaYgTAqIJZSn6WL4D10/s4000/20230828_194116.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="4000" height="149" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsTeti-103o_CVaPXT3sINSwCsLYlMIuhdE1B9-qK_XDc98vmJZ7Cvcz9YsrRT1hl1abN9BPdTaYHu5mx-4adGxOo7X9OS7rMXRH6_oOPO-3ONH_S333GhEEysj2zgSI4WDeD1BAT5sI259sZNMQWiSA9weQnkCgF-zyd9C_d3BaYgTAqIJZSn6WL4D10/s320/20230828_194116.jpg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Completed, calibrated and tested V4 boards.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: left;"><span style="font-family: verdana;">Firmware version is now v4.5, supporting the new hardware features and changing how unit-specific data is handled. </span></div><div class="separator" style="clear: both; text-align: left;"><span style="font-family: verdana;">All of the "Identity data", unique to each Gamma Dog unit, such as calibration offsets for various voltage dividers, pulse amplifier DC bias value, exact DAC reference voltage, serial number, etc is now stored in a dedicated "Read-Only" area of the EEPROM and not hard-coded in the firmware as before. </span></div><div class="separator" style="clear: both; text-align: left;"><span style="font-family: verdana;">Each unit is flashed with its "identity" during manufacturing, removing the need for unit-specific firmware code and simplifying firmware updates. </span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpnBXnoU2OHC5Sp1U3T0S5o2UqIJUTF6606XgDa5aMrzzgXed--e1IchMOpcL1svpUKOeeTDSGUGHjNsZCnobV9gEOfCJp1BBPRxdSELL4sa-Cdy1OP4dULJ88pck4MVJzrYKomoW5G1xwpk1EAviDpRIJUgdhRJ3Lod47BmighHC2O4t_Qh96LNC388k/s2886/PMT_Bias.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2886" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpnBXnoU2OHC5Sp1U3T0S5o2UqIJUTF6606XgDa5aMrzzgXed--e1IchMOpcL1svpUKOeeTDSGUGHjNsZCnobV9gEOfCJp1BBPRxdSELL4sa-Cdy1OP4dULJ88pck4MVJzrYKomoW5G1xwpk1EAviDpRIJUgdhRJ3Lod47BmighHC2O4t_Qh96LNC388k/s320/PMT_Bias.jpg" width="207" /></a></div><span style="font-family: verdana;">The PMT Bias reading shown when entering the menu system. </span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The value is constantly read and displayed at 4Hz until a button is pressed. </span></div></div></div><p></p>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-17532713348833593132023-05-11T13:46:00.065-04:002023-08-11T19:01:20.185-04:00Modifying Scionix-Holland 38B57/1.5M-E1 Scintillating Detector<p><span style="font-family: verdana;"> Commercial scintillating detectors are usuallu very expensive - hundreds, often thousands of dollars for a good size NaI(Tl) detector. Such detectors are not always affordable for amateurs, even on the secondhand market but for many applications they are the optimal, and sometimes the only solution.</span></p><p><span style="font-family: verdana;">There is a hidden, and often overlooked and underestimated gem though, made by a leading in the scintillator business Dutch company - the <b>Scionix-Holland 38B57</b>. This detector is nearly impossible to beat when it comes to value and it is pretty much "the best bang for the buck", delivering an incredible performance for its very low cost on the used parts market. The detector was manufactured as an OEM part about 10-15 years ago and not available for purchase as "new" but there are plenty of salvaged units out there, offered by various </span><span style="font-family: verdana;">Internet </span><span style="font-family: verdana;">sellers.</span></p><p><span style="font-family: verdana;">The 38B57 is a "classic" NaI(Tl) detector - the crystal is 38mm by 57mm (1.5" x 2.25"), surrounded by reflective powder, coupled with a 38mm Hamamatsu R980 10-stage head-on PMT and mounted in an Aluminum + Stainless Steel tube enclosure.</span></p><p><span style="font-family: verdana;">38B57 is employing an integrated design - the NaI(Tl) crystal is not encapsulated in its own aluminum canister, but it is directly interfaced (glued) to the PMT's Head-On photocathode window and then both, PMT's front part and the scintillating crystal are sealed together in an air-tight aluminum can. The assembly is wrapped with the Mu-metal magnetic / electrostatic shielding and together with the VD PCB is housed in a stainless-steel tube with an aluminum end-cap. </span></p><p><span style="font-family: verdana;">The integrated design keeps the cost down, but it means that this detector is not really serviceable beyond its voltage divider circuit / PCB - crystal and PMT cannot be decoupled from each-other and replaced without the complete destruction of the detector - this is one of the down sides of such design.</span></p><p><span style="font-family: verdana;">38B57 on the other hand, is a really a high-quality, spectroscopy grade detector and the lack of an additional glass window in front of the crystal improves the resolution by reducing photon refraction and/or reflection which would normally occur with the extra glass window of an encapsulated crystal.</span></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3As_vzUXINIu5A1ak2Ahd9BTn0vEkA4-3UlywbLM1FyM-cUJJ_Kf-3sJs2Ke619gwlHOjnuG2WlvOUfhDA4MDwrawl0b04JM8aFl0yT94UpGNdeq7RfVORo56tOqhqbahk8Y-C7jMUveSSEHd57Vkq9VS8KUKMTW8YoPYRl6QDYcP_2HCI8vLf-I_/s2051/Exploranium2.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1669" data-original-width="2051" height="260" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3As_vzUXINIu5A1ak2Ahd9BTn0vEkA4-3UlywbLM1FyM-cUJJ_Kf-3sJs2Ke619gwlHOjnuG2WlvOUfhDA4MDwrawl0b04JM8aFl0yT94UpGNdeq7RfVORo56tOqhqbahk8Y-C7jMUveSSEHd57Vkq9VS8KUKMTW8YoPYRl6QDYcP_2HCI8vLf-I_/s320/Exploranium2.jpg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">These detectors are part of the Exploranium GR-135 RIID device and hundreds such units are being decommissioned all the time by various US Government agencies (Border Patrol, Cost Guard, etc. ) and sold to equipment recyclers / salvagers.</span></div><p><span style="color: #0b5394; font-family: verdana;">These detectors will often show up on eBay for <b>as little as $80/ a piece (at the time of this writing, but prices do change) and sometimes for even less, making "good size NaI(Tl) Scintillator for under $100" possible!</b></span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6gpkz6CNrvB4Phc7lwtmn2d7wc2oX6-MroRUeeGjbcNJampWJm4cDCFb2bzyIyY7gxn_z9bUWejm7UdB1xjDmiBNDa4yreSRZsaTYOZDFtvrmUbVQnbBkQCpwY8aTuKpICjSRWiddfrijAadC9IqJs44z63JqFLXylHmQm6NQAH86Qg33KgSFY0Pn/s640/SAM_7044a.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="480" data-original-width="640" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6gpkz6CNrvB4Phc7lwtmn2d7wc2oX6-MroRUeeGjbcNJampWJm4cDCFb2bzyIyY7gxn_z9bUWejm7UdB1xjDmiBNDa4yreSRZsaTYOZDFtvrmUbVQnbBkQCpwY8aTuKpICjSRWiddfrijAadC9IqJs44z63JqFLXylHmQm6NQAH86Qg33KgSFY0Pn/s320/SAM_7044a.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">The 38B57 detector located in its black, shock-proof rubber protector, inside an Exploranium GR-135 Radioisotope Identifier unit. The white connectors on top are how the detector is connected to the electronics - the left one is the temperature sensor for compensation and the right one is for power to the detector.</div></span><p></p><p><span style="font-family: verdana;">Obviously, if the PMT or crystal are damaged because the unit was mistreated or accidentally dropped, the detector goes in the garbage bin but if they were treated well and are in a good, working condition, the detector can provide excellent post-service life as a Gamma Scintillator (Counting or Gamma Spectroscopy probe) - I routinely measure the FWHM resolution to be better than 7% (@662keV) for the 38B57 detectors. <b>This makes it an excellent choice for those who need a scintillator probe, are just beginning and want to try Gamma Spectroscopy and are on a budget.</b> </span></p><p><span style="font-family: verdana;">I, actually started my <a href="http://blog.kotarak.net/2020/07/gamma-spectroscopy-setup.html">Gamma Spectroscopy experiments</a> years ago with such detector.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEjiCUj8Jy4DmMlX0xkNOJk9b8ncQfarrPpzvkFVvNlfzea02g4BisWH0c3hMSy7GdsGiAhFb8EF0AGWaGh5VVzin3bGBrF6vQZjxYeAh_Dg4sgI_nh6dyuQ0LTIsrpcZha3zc9CM6SL5AQdpOKa3pYlhP9ZiOWGY2ERkUYjKVlH2jgVFzaogZmEYV/s2649/20230504_102549.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1857" data-original-width="2649" height="224" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEjiCUj8Jy4DmMlX0xkNOJk9b8ncQfarrPpzvkFVvNlfzea02g4BisWH0c3hMSy7GdsGiAhFb8EF0AGWaGh5VVzin3bGBrF6vQZjxYeAh_Dg4sgI_nh6dyuQ0LTIsrpcZha3zc9CM6SL5AQdpOKa3pYlhP9ZiOWGY2ERkUYjKVlH2jgVFzaogZmEYV/s320/20230504_102549.jpg" width="320" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">Unmodified, freshly decommissioned detectors.</span></div><div style="text-align: center;"><span style="font-family: verdana;">I cut off the connectors in order to remove the detector without damaging the protective rubber booth.</span></div><p></p><p><span style="font-family: verdana;">As the detectors are removed from the Exloranium GR-135 units and sold on eBay, <b>they are not directly useable</b> - they have a <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjup_23j2f-x7S6sYlPPCeD4YG3l0YcV-OZH2G0sd8mpXx50KF8NCpbaoxEEXXYaiqVXGK0lRzZjuiFWShEZs6GJFIlWnwIrV_nAhGTphc5UDwx67fQ_t7tuJAHQgfpiXIFLiOX9bsmjPvTs1KpTMwk0FyK8QTCO-X2V_2Sr_e7Eaa4HewmpfKGy6C5/s2010/38B57_Sch.jpg">custom voltage divider circuit</a> with transistors and diodes in the last stages, intended for use with the GR-135 hardware and <b>must be modified with a "standard" voltage-divider circuit to get the best performance</b> for both, linearity and resolution. Even the original connectors and the way they are powered is specific to the GR-135 unit. People have tried to use them without any modification, but the results are not great, and linearity is very poor. </span></p><p><span style="font-family: verdana;">The simple and easy to do modification brings it to a completely new level and one will be rewarded with a very capable detector once it is done.</span></p><p><span style="color: #0b5394; font-family: verdana;"><b>The modification process consists of removing the original voltage divider, installing a "classic" VD circuit with appropriate impedance and mounting a coaxial connector on the housing.</b></span></p><p><span style="font-family: verdana;"><b>This modification is not difficult but requires basic electronics, soldering and mechanical skills and one should be comfortable, working with SMD components in order to perform the procedure.</b></span></p><p><span style="font-family: verdana;"><b><br /></b></span></p><p style="text-align: center;"><span style="font-family: verdana; font-size: medium;"><b>Modification</b></span></p><p style="text-align: left;"><span style="font-family: verdana;"><span>Funny enough, the most difficult part of the modification process is opening and removing the rear aluminum cap of the detector.</span></span></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwj2FDVNzmJHDWyVGpoAl5-1vSPVr__HJR7yqmre7L7F8hKX9FK2mM-qzi6V_GN7a6MnQAMONiAXzsdgZFNdWGm4mOkpgmTHfCVFDN2F8Gx9DdojKOOOgmkQerVolpPSFjGSrGo2NSURSiITQyjM3colF5DQLR2nyX41p6IhlsTbVwE1LJDnHD8-9R/s2336/20230516_082453.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2336" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwj2FDVNzmJHDWyVGpoAl5-1vSPVr__HJR7yqmre7L7F8hKX9FK2mM-qzi6V_GN7a6MnQAMONiAXzsdgZFNdWGm4mOkpgmTHfCVFDN2F8Gx9DdojKOOOgmkQerVolpPSFjGSrGo2NSURSiITQyjM3colF5DQLR2nyX41p6IhlsTbVwE1LJDnHD8-9R/s320/20230516_082453.jpg" width="256" /></a></div><span style="font-family: verdana; text-align: left;">The cap is glued very well, with 2 different types of adhesives (including a special conductive adhesive) and one must use a heat-gun, an utility knife, flathead screwdriver and some patience to take the cap off. </span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana; text-align: left;">Fortunately, there are no heat sensitive components in the very back of the housing, </span><u style="font-family: verdana; text-align: left;"><b>but heating must be done quickly before the heat creeps down the housing, towards the NaI(Tl) crystal</b>.</u><span style="font-family: verdana; text-align: left;"> </span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana; text-align: left;">TIP: Holding the detector with a moist paper towel can provide additional cooling and heatsinking effect to the crystal housing while performing this procedure.</span></div><p></p><p><span style="color: #990000; font-family: verdana;"><b>Enemy #3 of these inorganic scintillating crystals are rapid temperature changes which can cause the crystal to crack. (Enemy #1 is moisture and Enemy #2 is mechanical shock)</b></span></p><p><span style="font-family: verdana;"><i>It requires quite a bit of heat for the adhesive to fail and let the cap go. </i></span></p><p><span style="font-family: verdana;"><i>Inserting the blade of the utility knife between the edge of the tube and the cap while hot, allows for the cap to be pried off - this action must be carried out repeatedly at different spots around the perimeter of the cap until it comes off.</i></span></p><p><span style="font-family: verdana;"><i>If the cap doesn't budge initially, just reheat quickly to a higher temperature, while monitoring the temperature of the crystal housing and once the cap is open, slowly cool down the top, heated edge, of the stainless-steel tube.</i></span></p><p><span style="font-family: verdana;">The aluminum cap can retain heat, so the process is as follows - heat up the cap, then quickly put down the heat-gun and try to pry it off with the utility knife, then repeat as necessary and change position around the perimeter of the cap.</span></p><p><span style="font-family: verdana;">Once the utility knife blade widens the gap</span><span style="font-family: verdana;"> </span><span style="font-family: verdana;">enough</span><span style="font-family: verdana;"> </span><span style="font-family: verdana;">to slip in a flat-head screwdriver between the edge and the rim of the cap, things become easy as twisting the screwdriver applies quite a bit of force to pry the cap open.</span></p><p><span style="font-family: verdana;">Some caps will come off quickly and easily, but others will have excessive amount of glue and can be "tough cookies".</span></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqO4IZy57GSxF5RbDgUTUBedlhMJYZAuOyryFsMgzsn0CqkmDp_T9b4kedWFPrO_KpXbOJmGNa87exI5siVNtOW2SEuPXDXOsryOsMzlbff9tYV_D6ZfC8NPcqS_4NzE5UOpn4fy727btwYbcwXdFO9pJSEsFJyFE69HWjn989ASANHzQ3dxzhZZm5/s2229/20230505_132729.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2229" data-original-width="1856" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqO4IZy57GSxF5RbDgUTUBedlhMJYZAuOyryFsMgzsn0CqkmDp_T9b4kedWFPrO_KpXbOJmGNa87exI5siVNtOW2SEuPXDXOsryOsMzlbff9tYV_D6ZfC8NPcqS_4NzE5UOpn4fy727btwYbcwXdFO9pJSEsFJyFE69HWjn989ASANHzQ3dxzhZZm5/s320/20230505_132729.jpg" width="266" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">Once the aluminum rear cap is removed, this is how the detector looks on the inside. </div></span><p></p><p style="text-align: center;"><span style="font-family: verdana;">Next step is to remove the silicone sealant, cables and the cable grommet.</span></p><p style="text-align: center;"><span style="color: #990000; font-family: verdana;"><b>DO NOT try to remove the stainless-steel tube from the bottom, aluminum part of the housing in order to gain better access to the PCB - it is not needed, and any such attempts could lead to the destruction of the detector!</b></span></p><p style="text-align: center;"><span style="font-family: verdana;">All of the work is carried out through the back opening.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmojGZ3H7ileLMId2dDhan7C3wSVYB1K2KrlHVQOkUxjHkTMP90N_LQ_e-44Fy76T5VmgwWA2V3TOTjoysQqsY1x1ntxvQ_Vwx8fMguQ-vOearWxtuHrz4ZPWm06s9dgb-Z7LKYCxfwkeIU0TpXweEwtPM8FHtCr5cfOaLNd5eDLvBeM_Tve5iCBRI/s2102/20230505_133018.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2102" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmojGZ3H7ileLMId2dDhan7C3wSVYB1K2KrlHVQOkUxjHkTMP90N_LQ_e-44Fy76T5VmgwWA2V3TOTjoysQqsY1x1ntxvQ_Vwx8fMguQ-vOearWxtuHrz4ZPWm06s9dgb-Z7LKYCxfwkeIU0TpXweEwtPM8FHtCr5cfOaLNd5eDLvBeM_Tve5iCBRI/s320/20230505_133018.jpg" width="284" /></span></a></div><p style="text-align: center;"><span style="font-family: verdana;">I cut the cables for this picture, but </span><span style="font-family: verdana;">actually</span><span style="font-family: verdana;"> the wires</span><span style="font-family: verdana;"> </span><span style="font-family: verdana;">should be de-soldered and completely removed. The picture shows the original Voltage Divider, with the transistors in the last stages. It is a tapered VD and the total impedance is fairly low - around 12MOhms.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDls6W8JodBTOcGwQGKbMjNl5d9AMldT7pwgYJZi5FNIC8ueIV-dNcxWu6PYJneW5vIn9H-EcAIyKKY9UzpWcwz3U7_ZUahfOpYjyBackFaMQHLj8HIJ_HBrta_Nwdtw8PfCJRYSqAmqfgOpAwYVXu8HhaqQEFBLLbaffGN5tfsxBPu7o9mu0njbDU/s2102/20230505_133018%20-%20Copy.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2102" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDls6W8JodBTOcGwQGKbMjNl5d9AMldT7pwgYJZi5FNIC8ueIV-dNcxWu6PYJneW5vIn9H-EcAIyKKY9UzpWcwz3U7_ZUahfOpYjyBackFaMQHLj8HIJ_HBrta_Nwdtw8PfCJRYSqAmqfgOpAwYVXu8HhaqQEFBLLbaffGN5tfsxBPu7o9mu0njbDU/s320/20230505_133018%20-%20Copy.jpg" width="284" /></span></a></div><p style="text-align: center;"><span style="font-family: verdana;">Most components of the original VD must be removed, and some will be replaced with different values. The only components that stay are the 3 capacitors shown on the picture - everything else, marked with "X" in this picture, must be de-soldered.</span></p><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYAMFEHHNi-jobwQnGgah8rbgySxaa08h5jRz7ru6l8WhJBFVuDj30TZIcZhf2fYDr05iRb3d3eU3MO9-EL-swfPgd6tlAmnvwKheX5PHQ3KnSa0FFHvlEmEEuhdbZ89S_glYFEuESuLyawwRX1wv3Y7i8O6Bn-g6ntWnd-VT0DP-IkOs--XKCIKl7/s3869/20230427_113624.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3869" height="154" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYAMFEHHNi-jobwQnGgah8rbgySxaa08h5jRz7ru6l8WhJBFVuDj30TZIcZhf2fYDr05iRb3d3eU3MO9-EL-swfPgd6tlAmnvwKheX5PHQ3KnSa0FFHvlEmEEuhdbZ89S_glYFEuESuLyawwRX1wv3Y7i8O6Bn-g6ntWnd-VT0DP-IkOs--XKCIKl7/s320/20230427_113624.jpg" width="320" /></a></span></div><span style="font-family: verdana;">The best and fastest way to remove these SMD resistors is using 2 soldering irons equipped with fine tips (I use ETP tips for this task with my Weller stations). This method also carries less chance for PCB damage. Each resistor is heated simultaneously on both sides and picked up by the two soldering iron tips as if tweezers are used. It takes me just a few minutes to remove all of the unnecessary components. Solder wick is used to clean the pads and prepare them for the new resistors. The old soldering flux can be cleaned off with alcohol pads or alcohol-soaked Q-tips.</span><p></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4Lb5SJGWZ-UfEY-Qq8KuLN5oCXbJzyAdWZ2aAGfISs-k_iM0TcbMw_4fm2yQjI9NMM7C_4MU12c6zmMJUfGJT5rJTATqt4rDe744wjktFBBQ2Xqmunhr-lmXGw9jqj6GD2mcTUF6yxR1XCA9uJSxHj4bMN5IoUfm18yPgQ7-nuwAFU_oXllBZeg1h/s2093/20230509_102440.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2093" data-original-width="1867" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4Lb5SJGWZ-UfEY-Qq8KuLN5oCXbJzyAdWZ2aAGfISs-k_iM0TcbMw_4fm2yQjI9NMM7C_4MU12c6zmMJUfGJT5rJTATqt4rDe744wjktFBBQ2Xqmunhr-lmXGw9jqj6GD2mcTUF6yxR1XCA9uJSxHj4bMN5IoUfm18yPgQ7-nuwAFU_oXllBZeg1h/s320/20230509_102440.jpg" width="285" /></a></div><span style="font-family: verdana;">This picture shows how the PCB should look like after de-soldering the original divider. 3 out of the 4 SMD capacitors (10nF/200V) are left in place. The 4th capacitor on the very left is removed and later a resistor will be installed in this position.</span><br /><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtG_ZdLnRFmTbddlRRIH7yOJSXAyibSguBCdWbn2f1mNidjjPLDoftVXSwSclLRr8HVmQ6MEaealkrSq0fi1QP3fy92wTm3Su8uSS28b_IXOedrEswNc7rlmrKf8sFmkmEQYHv7xaAAYMPX2qaXHS8FCiyc-PbVq_oSlFw-TSvLZlDC94W-vCOtgnB/s2652/20230509_111353.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2652" data-original-width="1859" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtG_ZdLnRFmTbddlRRIH7yOJSXAyibSguBCdWbn2f1mNidjjPLDoftVXSwSclLRr8HVmQ6MEaealkrSq0fi1QP3fy92wTm3Su8uSS28b_IXOedrEswNc7rlmrKf8sFmkmEQYHv7xaAAYMPX2qaXHS8FCiyc-PbVq_oSlFw-TSvLZlDC94W-vCOtgnB/s320/20230509_111353.jpg" width="224" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">Next step is to install the SMD resistors for the new, "standard" voltage divider. I have discussed choosing resistors for PMT VD in other posts but for general purpose (counting with Eberline or Ludlum meters for example) 10 MOhm resistors are normally used. This is a 10-stage PMT with 2R (20M) between K and Dy1 and R(10M) for all other resistor positions (between the rest of the Dynodes). The footprint on the PCB requires 1206 package resistors. The total impendence of the VD will be 120M, which causes minimal voltage drop even with weak HV power supplies. </div><div style="text-align: center;">(For Spectroscopy, a lower value for R should be used - 1M or 2M is generally a good choice.)</div></span><p></p><p style="text-align: left;"><span style="font-family: verdana;">I use 10 Mohm / 1/4W / 1206/ 0.1% tolerance resistors - Digikey part # 749-MCA1206MD1005BP500CT-ND - Vishay High Stability chip resistors.</span></p><p style="text-align: left;"><span style="font-family: verdana;">Resistance tolerance is not super-critical as there are already differences in the PMT's Dynode stages to begin with, and 1% tolerance should work just as well. </span></p><p style="text-align: left;"><span style="font-family: verdana;">All resistors should be installed just as shown on the picture.</span></p><p style="text-align: left;"><span style="font-family: verdana;">(tip: buying these resistors in quantity of 100 pcs from Digikey is more cost-effective, especially if more than one detector is modified as each detector takes 12 resistors)</span></p><p style="text-align: left;"><span style="font-family: verdana;"><i>On the picture above:</i></span></p><p style="text-align: left;"><span style="font-family: verdana;"><i>A. Resistor is installed in the position of the removed capacitor.</i></span></p><p style="text-align: left;"><span style="font-family: verdana;"><i>B. Resistor is installed <u>on top</u> of the capacitor and in parallel.</i></span></p><p style="text-align: left;"><span style="font-family: verdana;"><i>C. Two resistors in series are installed between Dy1 and K. Single 2xR resistor (in this case 20M) can also be used but I found to be more convenient if I use 2 resistors as the distance between the pads allows for this, looks clean and helps if 2R is not a standard value.</i></span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXP8asRkLL0KHcFzbSiyWSW4rqP1ctfUYyZO2JgQt61_sLPoe4zOssFFIzdVNYFoJeop1dzRaxsDOIR62xfnz5zoaOlqZyXsGyscripidYTxdYqegyr5ox56UYLuxrR6rYjrJuAuU_hB_tn7Gu0K5ydjMwQqh-soTwf3dYa5rwWZT3fhEkogD8uMZw/s2528/20230509_111411.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2528" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXP8asRkLL0KHcFzbSiyWSW4rqP1ctfUYyZO2JgQt61_sLPoe4zOssFFIzdVNYFoJeop1dzRaxsDOIR62xfnz5zoaOlqZyXsGyscripidYTxdYqegyr5ox56UYLuxrR6rYjrJuAuU_hB_tn7Gu0K5ydjMwQqh-soTwf3dYa5rwWZT3fhEkogD8uMZw/s320/20230509_111411.jpg" width="236" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">This is how the PCB should look like after all of the resistors are installed. The yellow wire is connected to the PMT's Anode (P) pad and supplies both, HV Bias to the PMT and return signal - it returns back the positive pulses generated by the PMT to the external circuit.</span></div><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqPZUmUA-cYkytQRRM8JOtkfgX5LZ_J2hCpW97N_MO_44lpq_KIR8XSnlZkfzGJmJP_AThk2kUpPkL9EfdGwJ6sA8_MQ-z0Zmo3kITyHnHM7K4bZ4liDT7yMUd-vYYkh8VjuSCaApEh5Mbaet4UK8TJ1Tr4ZipzWY-BJfJj0jO4jEatj1OyHBp_WQS/s2526/20230509_111914.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2526" data-original-width="1867" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqPZUmUA-cYkytQRRM8JOtkfgX5LZ_J2hCpW97N_MO_44lpq_KIR8XSnlZkfzGJmJP_AThk2kUpPkL9EfdGwJ6sA8_MQ-z0Zmo3kITyHnHM7K4bZ4liDT7yMUd-vYYkh8VjuSCaApEh5Mbaet4UK8TJ1Tr4ZipzWY-BJfJj0jO4jEatj1OyHBp_WQS/s320/20230509_111914.jpg" width="237" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">The grounding lead wire, soldered on one end, to the detector's housing must be connected to the K pad (PMT's Cathode). The stainless-steel part of the housing acts as electrostatic shield for the PMT. </div><div style="text-align: center;"><br /></div></span><div><span style="font-family: verdana;">After the K lead (black wire) is installed, the grounding wire to the housing is connected at the junction of K-2R. </span><div><span style="font-family: verdana;">If the original wire is not long enough to reach the K pad, it can be extended with a piece of bus wire, as shown.<br /></span><p></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSDhxXXkow_dkX9ZHagBSDr2091NdaJDwf9DM4KIQVPURZWRhzyLo6DupAzCKxBBEVSZ6hbJHRgoWu2eoXPt1KSg9ZcklXhyadi3xmRwH3fxWodGg84XI0SIEvAwLF2mrjKK9NychnLU3ZqBdxWd0V2PFV40RxgMnnhDkc-618AYzwHDKB5XbGpwma/s2258/20230509_112237.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2258" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSDhxXXkow_dkX9ZHagBSDr2091NdaJDwf9DM4KIQVPURZWRhzyLo6DupAzCKxBBEVSZ6hbJHRgoWu2eoXPt1KSg9ZcklXhyadi3xmRwH3fxWodGg84XI0SIEvAwLF2mrjKK9NychnLU3ZqBdxWd0V2PFV40RxgMnnhDkc-618AYzwHDKB5XbGpwma/s320/20230509_112237.jpg" width="265" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">The two pads circled on the picture must be bridged with a short piece of jump wire. </div><div style="text-align: center;"><b>This is an important step and should not be omitted !</b></div><div style="text-align: center;"><b>If the jumper is not installed the detector will not work. </b></div><div style="text-align: center;"><br /></div><div style="text-align: center;">This is the <a href="https://1.bp.blogspot.com/-473UDhajb00/Xxh8YT27aQI/AAAAAAAAB-o/VFPBdfscj84B18zFDBRmv66Sd8zdeUXXACLcBGAsYHQ/s1680/Scionix%2B38B57%2BCircuit%2BDiagram%2B-%2BMODED%2B120M.JPG"><span style="color: #0b5394;"><b>schematics</b></span></a> of how the modified detector should be wired. </div><div style="text-align: center;"><br /></div></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8LZyh2YWo_tYzhvjYvbE_MyMWvBANguoAsHkib8NYdi0sGahVCPPb4cITFP5Y3jAXkh_n7gTAAcjgb1yXx8KT9wshASHn9mCUGmRs_tOWjsJME2-Pn99PUU1OcROINnyH2E2eZO1NO3ufNs3Fyh4aXdXQuXB9kA-X1HXNWlMS0BGQVtVMW8pIb8rR/s2375/20230428_101323.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1541" data-original-width="2375" height="208" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8LZyh2YWo_tYzhvjYvbE_MyMWvBANguoAsHkib8NYdi0sGahVCPPb4cITFP5Y3jAXkh_n7gTAAcjgb1yXx8KT9wshASHn9mCUGmRs_tOWjsJME2-Pn99PUU1OcROINnyH2E2eZO1NO3ufNs3Fyh4aXdXQuXB9kA-X1HXNWlMS0BGQVtVMW8pIb8rR/s320/20230428_101323.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">The aluminum cap is drilled in the center and a female BNC connector is installed - I recommend using a good quality connector with Teflon center conductor, like Amphenol UG-625/U. </div><div style="text-align: center;">Alternatively, a MHV or even SHV connector can be used but there is not much clearance on the inside and fitting a standard SHV bulkhead connector will be rather difficult.</div><div style="text-align: center;"><br /></div></span></div><div><span style="font-family: verdana;">The drill diameter for the hole in the cap is 3/8" for a round connector and if the connector barrel is D-shaped (to prevent rotation), then 11/32" drill bit is used, and the rest is shaped with a set of small round and small flat files, until the connector can just fit through the hole without being able to rotate. Using connectors with D-shaped barrels is the better choice as it locks the barrel in place and prevents the connector from loosening itself when operated.</span><span style="font-family: verdana;"><br /></span><p></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivlyOsZcLvawiriTm6ZjJ5PIFjL5VfArmmen_k_t980YOzU-OWGXrA9dw1gim-O_594oiR7kaxyYwizW5OQsQxAIvrvNZ-4OUuOhwHuTG9yK0lod0LGoM-rrZG4y91Kseyd4WyvveSOH3e2zr_p-0oXXfrbOPuymJuAVvsVi5k7NpK4fu6oHx1M_rd/s3840/IMG-20230508-WA0002.jpeg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="3840" data-original-width="2160" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivlyOsZcLvawiriTm6ZjJ5PIFjL5VfArmmen_k_t980YOzU-OWGXrA9dw1gim-O_594oiR7kaxyYwizW5OQsQxAIvrvNZ-4OUuOhwHuTG9yK0lod0LGoM-rrZG4y91Kseyd4WyvveSOH3e2zr_p-0oXXfrbOPuymJuAVvsVi5k7NpK4fu6oHx1M_rd/s320/IMG-20230508-WA0002.jpeg" width="180" /></a></div><span style="font-family: verdana;">The yellow and black wires (silver-plated stranded wire with Teflon insulation) are soldered to the BNC connector. These wires are about 1" long (but could be a bit shorter) and are carefully bent and routed not to touch the board or components when the cap is closed.</span><p></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuUMIVseSD9O73sCtelGx2ixO-nHbIOglaca52Y2az4SL0IV1Jb5jWoemL00334NOPp7WR75pI3fs-Hj33CZL0AE4AAIaOM8sDJUuxfUrpQkW_MJBgT0asJLTOJcP7yMhggyoi2S3HWC16Pah9UFNUEZEXhYg0HBsxh_fHm6Aww9ytbnY0GtCaCclg/s2160/IMG-20230508-WA0006.jpeg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2160" data-original-width="1738" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuUMIVseSD9O73sCtelGx2ixO-nHbIOglaca52Y2az4SL0IV1Jb5jWoemL00334NOPp7WR75pI3fs-Hj33CZL0AE4AAIaOM8sDJUuxfUrpQkW_MJBgT0asJLTOJcP7yMhggyoi2S3HWC16Pah9UFNUEZEXhYg0HBsxh_fHm6Aww9ytbnY0GtCaCclg/s320/IMG-20230508-WA0006.jpeg" width="257" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">The original cable opening is sealed with a piece of self-adhesive copper tape and a length of Kapton tape on top. The housing should be completely light-proof and air-tight. RTV sealant around the BNC connector (on the inside) can be applied before the connector nut is tightened, to seal it as well. </div></span></div><div><div style="text-align: center;"><span style="font-family: verdana;">The aluminum rear cap is glued back with hot-melt glue to the stainless-steel housing.</span></div><div class="separator" style="clear: both; text-align: center;"><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEic2IQX1DyhRzUcDzBWdkrf6H0lXN2ljC_h_40hpuUMD_-h9oLG5dz5TE5AkLhjzab9DJL4LLsipqzdZVxJx1dOgHm4tln0jSjV5zWlfxnTZjmJ7qQe5ux6-hXjizFLYLVG8ZPqvMAi7g2ciWtda3IH1MNYfDBf-xF4IKFxHns_Kyr50BE78uNfILAR/s4000/20230428_112155.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="4000" height="149" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEic2IQX1DyhRzUcDzBWdkrf6H0lXN2ljC_h_40hpuUMD_-h9oLG5dz5TE5AkLhjzab9DJL4LLsipqzdZVxJx1dOgHm4tln0jSjV5zWlfxnTZjmJ7qQe5ux6-hXjizFLYLVG8ZPqvMAi7g2ciWtda3IH1MNYfDBf-xF4IKFxHns_Kyr50BE78uNfILAR/s320/20230428_112155.jpg" width="320" /></a></div></div><p></p><p style="text-align: center;"><span style="font-family: verdana;">I also seal the seam between the aluminum part of the housing and the stainless-steel tube with a strip of Kapton tape - just for "good measure".</span></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9cRoCUiRUd9VZjY9JF3-ZTbrYB3zfuNsvhXpp9MOZuhBmnCECOMynkAZ5qRQuIX0ss7ZdPrQlK_11RFE-8601icFe4tohsM4Lb-MmDr4CmzSLi1Yt21_SRRC58ZLUvtRIS6240YgHBie4FYxywae3u99gnEcuVtNy3_c35N3CPp1aKfvbRYCUljxk/s3245/20230511_141734.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1625" data-original-width="3245" height="160" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9cRoCUiRUd9VZjY9JF3-ZTbrYB3zfuNsvhXpp9MOZuhBmnCECOMynkAZ5qRQuIX0ss7ZdPrQlK_11RFE-8601icFe4tohsM4Lb-MmDr4CmzSLi1Yt21_SRRC58ZLUvtRIS6240YgHBie4FYxywae3u99gnEcuVtNy3_c35N3CPp1aKfvbRYCUljxk/s320/20230511_141734.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">The modified 38B57 detectors - </span><span style="font-family: verdana;">completed and tested, ready to be installed in Gamma Dogs. After the modification, these detectors can be directly connected to counters such as Eberline ASP-1 or most Ludlum counters. They will certainly outperform Ludlum 44-2 probe for example. </span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi96rMXpYk36MBsF76QRQb93H8BEtYjbY2dmrpRGvuP6AGmrh9cqAZu6ALHnbdyI4N2jdzsMMvStCJCR4ng-ktR6TBFyFGjC5SLd61GBIDyQGQDdtyvsbVPiAkOf-I5lJHyNl2LkdecoG3pksOC4g2tCakvSPz6ztRFTAy5iNPYjZoms01pIZ63lmby/s1764/SCE057.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="978" data-original-width="1764" height="177" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi96rMXpYk36MBsF76QRQb93H8BEtYjbY2dmrpRGvuP6AGmrh9cqAZu6ALHnbdyI4N2jdzsMMvStCJCR4ng-ktR6TBFyFGjC5SLd61GBIDyQGQDdtyvsbVPiAkOf-I5lJHyNl2LkdecoG3pksOC4g2tCakvSPz6ztRFTAy5iNPYjZoms01pIZ63lmby/s320/SCE057.png" width="320" /></a></div>Here is a Gamma Spectroscopy plot done with one of the modified detectors.</div><div style="text-align: center;">The FWHM resolution for 662keV (1uCi of Cs-137 source disk) is 6.9%. The detector was running on 575V and connected to a Gamma Spectacular GS-USB-PRO. (The second peak from the left is XRF coming off the lead castle - the peak is suppressed due to the graded shielding).</div><div style="text-align: center;">These detectors output ~110 CPS (6600 CPM) for the Natural radiation background at my location when unshielded (~0.1 uSv/h).<br /></div><div style="text-align: center;"><br /></div><div style="text-align: center;"><br /></div><div style="text-align: center;"><span style="font-size: medium;">"Gamma Spectroscopy Only" Use / 12MOhm Total Impedance VD</span></div><div style="text-align: center;"><br /></div><div style="text-align: left;">If the detector is to be used for Gamma Spectroscopy only, with GS-USB-Pro or a Lab Grade PS driver providing "stiff" HV Bias, lower impedance VD will result in better stability, better SNR and even faster response. </div><div style="text-align: left;">The 12MOhm VD on the other hand pulls more current and it is too low for portable, battery operated, meters - it will cause a significant voltage drop and an increased battery usage.</div><div style="text-align: left;"><br /></div><div style="text-align: left;">The original VD can be modified by removing the active components and only some of the resistors while keeping all of the existing 1MOhm resistors - this is really simple and logical, but I decided to provide the pictures anyways in case somebody wants to follow this guide as a step-by-step.</div><div style="text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLX7CwmcNjl65Lle_TXPRESh8JiSxTQH8RaJRvmMSLcI_Ks6C3KQGPs6zRemlYQ1jKAJsXNZ1Ev2oF6PZkcXtVqVKZapikz1EPjJlXE3JX5JbhjeF4IeERTcP-NvhekyJw7tJ54I4jHX01wxVnJn_4WbQSdkr5qF8rdJaYEe0Cj1BIBVSJzUDqRFWx/s2102/20230505_133018%20-%20Copy%20(2).jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2102" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLX7CwmcNjl65Lle_TXPRESh8JiSxTQH8RaJRvmMSLcI_Ks6C3KQGPs6zRemlYQ1jKAJsXNZ1Ev2oF6PZkcXtVqVKZapikz1EPjJlXE3JX5JbhjeF4IeERTcP-NvhekyJw7tJ54I4jHX01wxVnJn_4WbQSdkr5qF8rdJaYEe0Cj1BIBVSJzUDqRFWx/s320/20230505_133018%20-%20Copy%20(2).jpg" width="284" /></a></div><br /><div style="text-align: center;">Only the marked with "X" components should be removed, keeping all existing 1Mohm resistors in place.</div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoE28s1M7MItv-9J62l34AnMPoRCFhEyKao02c8rFMSkZDV-X4xhl27380l1kqDZ1s2TkiGplRNYahSP-aGWIbmb6cejk7rELVkBTRKMO47w-pX4vscjlLDS3RjWsPI5ffzsVuj0Z4fqsmGkNb8ynpWwx3mtXyX4AsrblXyFlEzKdAC6u5OtgeYAnl/s2177/20230505_134255.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2177" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoE28s1M7MItv-9J62l34AnMPoRCFhEyKao02c8rFMSkZDV-X4xhl27380l1kqDZ1s2TkiGplRNYahSP-aGWIbmb6cejk7rELVkBTRKMO47w-pX4vscjlLDS3RjWsPI5ffzsVuj0Z4fqsmGkNb8ynpWwx3mtXyX4AsrblXyFlEzKdAC6u5OtgeYAnl/s320/20230505_134255.jpg" width="275" /></a></div><br /><div style="text-align: center;">This is how the PCB should look like after de-soldering the unnecessary components.</div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilpYqR8BpDHv3P6IFjOMNVZEMx_c60Gi-bKYnSXzg6AivM_9D-ZepSKz5B47Xbanv_lcDN6sGzTXplE82xytXya3ESoku00-1kgWkXvvFEBLKAGIi_YB5sIxwStWWofOAcrQ4dHB6Unu8uEoE0ESk3G8iwCuH_tTH9suRoVcHiRxrNzOhAF7E4vQuU/s2757/20230505_150917.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2757" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilpYqR8BpDHv3P6IFjOMNVZEMx_c60Gi-bKYnSXzg6AivM_9D-ZepSKz5B47Xbanv_lcDN6sGzTXplE82xytXya3ESoku00-1kgWkXvvFEBLKAGIi_YB5sIxwStWWofOAcrQ4dHB6Unu8uEoE0ESk3G8iwCuH_tTH9suRoVcHiRxrNzOhAF7E4vQuU/s320/20230505_150917.jpg" width="217" /></a></div><div style="text-align: center;">Additional 5x 1MOhm resistors are needed (I used the ones salvaged from other units) to complete the 12MOhm Voltage Divider.</div><div style="text-align: center;"><br /></div><div style="text-align: center;">The rest of the modification is just as outlined above.</div></span><p></p></div></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-17484174562047007952023-04-04T10:11:00.020-04:002023-12-01T08:32:01.024-05:00Building a Scintillator, using CsI(Na) crystal and Hamamatsu R6231 PMT<p><span style="font-family: verdana;"> This scintillator build is not much different than the others except for using a CsI(Na) crystal and 2" / 51mm PMT.</span></p><p><span style="font-family: verdana;"> I understand that people use these posts as a guide when building their own scintillators so I decided to document it as it might provide additional information, which I might have missed in previous posts.</span></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIXs-w_nw42sHdHegiCOIQMNTRBAne1GVikoge-ekbRy_rJ0CueyJT6kXew60hId8UgzExPtaPmAjz9g6ONeTZ3f8lLl7yirKeY_ExZzhTsOjhUJAkMrwshLoTeMuXNdzeZP1l5qPDkljJof9SPJEvV65XEopWlxtXIyu1-6kFrpDs_uK5zG3Dqgap/s1891/20230208_131909.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1891" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIXs-w_nw42sHdHegiCOIQMNTRBAne1GVikoge-ekbRy_rJ0CueyJT6kXew60hId8UgzExPtaPmAjz9g6ONeTZ3f8lLl7yirKeY_ExZzhTsOjhUJAkMrwshLoTeMuXNdzeZP1l5qPDkljJof9SPJEvV65XEopWlxtXIyu1-6kFrpDs_uK5zG3Dqgap/s320/20230208_131909.jpg" width="316" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">Using Gamma Spectacular PCB for R6231. This PCB is designed for both, single wire (HV Bias + Signal) and 2 wire (HV Bias and a separate Signal line) interface. I populated the PCB for the Single wire interface using R value of 5.6M for the voltage divider. Had to improvise a bit with the 2R resistors between K-G and G-D1 as there was only one footprint per resistor but there are no 11.2M resistors.</span></div><div style="text-align: center;"><span style="font-family: verdana;">Total resistance of the VD is 67.2M.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;">Voltage-Divider impedance is not a super-critical parameter, but it is important to consider based on the application. For example, with battery-powered counters and meters where the HV Bias supply can't take much load, high-impedance is preferred as the lower current will reduce the voltage drop. Some PS will drop the output voltage with impedance as low as 60M. In these cases, a total impedance of 120M will work well. High-impedance divider on the other hand will have lower SNR (Signal-to-Noise Ratio) and linearity could suffer as well - for Gamma Spectroscopy with benchtop / lab-grade power supplies, VD impedance of 12M will work great.</span></div><div style="text-align: left;"><span style="font-family: verdana;">For this detector I went "in the middle of the road" with VD around 70M.</span></div><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsnILe9yiWZApeljdpMSJekJIwqQjksg68-aFPxfB4m6ImQGm9sR_b7E5DkkLj7BTk-bMfDjfH8aaMhPB4USmZqcCkJTt7N_KB7kwcyL3tOBhTF0Ew5KsNG08fwVDbq1PbcJWPOIbxOA7jI1iynCXW1fmg_Zk55ZJJIeAWcNh4ogw1Cg4eFXYZin_p/s1866/20230208_132628.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1866" data-original-width="1865" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsnILe9yiWZApeljdpMSJekJIwqQjksg68-aFPxfB4m6ImQGm9sR_b7E5DkkLj7BTk-bMfDjfH8aaMhPB4USmZqcCkJTt7N_KB7kwcyL3tOBhTF0Ew5KsNG08fwVDbq1PbcJWPOIbxOA7jI1iynCXW1fmg_Zk55ZJJIeAWcNh4ogw1Cg4eFXYZin_p/s320/20230208_132628.jpg" width="320" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">Machined PMT rear cap, completed PCB and the PMT ready for the final assembly.</div><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_0cv1G3FydB4yQn_go_HZv0ZGNWnvNHuV13Vkc-OsehJDyd5KUqaO-ea5lvgJymMG6c45TYx625s-XUlwHo1DSeaBeYk3TdVADo5cx8tG4sw_HI9MrrOn-UizRjvmVIfG9KNobs_T8eJJkP2QHJoPteU9sk7cn-3eou-F9DdMSZBUAeenMfPFzi2W/s1980/20230208_132842.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1633" data-original-width="1980" height="264" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_0cv1G3FydB4yQn_go_HZv0ZGNWnvNHuV13Vkc-OsehJDyd5KUqaO-ea5lvgJymMG6c45TYx625s-XUlwHo1DSeaBeYk3TdVADo5cx8tG4sw_HI9MrrOn-UizRjvmVIfG9KNobs_T8eJJkP2QHJoPteU9sk7cn-3eou-F9DdMSZBUAeenMfPFzi2W/s320/20230208_132842.jpg" width="320" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">The PMT is a 2" Hamamatsu R6231 - the little brother of R6233. The only difference between the two is really the size - all other specs are the same.</span></div><div style="text-align: center;"><span style="font-family: verdana;">R6233 is one of the best all-around PMTs - I've built more than a dozen detectors with it and absolutely love it - the R6231 should be just as good!</span></div><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhj4va_17p_BgmALrOL87d5FZVpfQq5bA_NsQ4J5WXCG4Yp8fdEoiHB8CUQZXdOdXb1EJU4os5pln30iSZj63MTnPswFd-2W6-sL6Qy3q7leTPh1cOW7p-Fe0CwCcWqEFoeS-CRss2kqdmZzaCC8KaeaABXM4AkWg7iznPbF9nCEyiTGMhhtuNzmzoh/s3023/20230209_083140.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="3023" data-original-width="1865" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhj4va_17p_BgmALrOL87d5FZVpfQq5bA_NsQ4J5WXCG4Yp8fdEoiHB8CUQZXdOdXb1EJU4os5pln30iSZj63MTnPswFd-2W6-sL6Qy3q7leTPh1cOW7p-Fe0CwCcWqEFoeS-CRss2kqdmZzaCC8KaeaABXM4AkWg7iznPbF9nCEyiTGMhhtuNzmzoh/s320/20230209_083140.jpg" width="197" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">VD PCB installed on the back of the PMT with the two silver-plated, Teflon insulated lead wires. </span></div><div style="text-align: center;"><br /></div></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuyx79mnaNSp428GUeyqWxCzxGM7u8i457p0FADek0m5qQW5fuK73MOX3U_pHiP61Esz4eJhucOd_0V4CsWFSdY9Yl4kYlWx74dGHCs3W0kGXW_PcVoY8glO3ei6oBOjRjeNcDYxtmPq5ZALa-Ef7Gx2Db49rO-le_l92Gn8qIXYRkIvw5nOnxYf8f/s2672/20230209_091403.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2672" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuyx79mnaNSp428GUeyqWxCzxGM7u8i457p0FADek0m5qQW5fuK73MOX3U_pHiP61Esz4eJhucOd_0V4CsWFSdY9Yl4kYlWx74dGHCs3W0kGXW_PcVoY8glO3ei6oBOjRjeNcDYxtmPq5ZALa-Ef7Gx2Db49rO-le_l92Gn8qIXYRkIvw5nOnxYf8f/s320/20230209_091403.jpg" width="224" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">Installing the MIL-grade BNC connector (Amphenol UG-625 B/U). </span></div><div style="text-align: center;"><span style="font-family: verdana;">There is a wire fed thru a small hole in the cap for grounding the electrostatic shield. Heat shrink tubing is added for extra insulation of the Anode lead and both wires are coiled into "springs" and away from each-other before closing the PMT cap so they don't press on the board and stay away from the components.</span></div><div><span style="font-family: verdana;"><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi2Mefv1KLm43oqPnAYdkhwpMrv4hJ_6D6y89fs0UMXzuiirRsm9Dp7VXLazLH2P4iDfizOFLzxhVtC1bDsBBGle5-Z7tBcnfymr3b-i5oGgbOoqnGm-74q3-CRX8YvCbNfAxL5jt-AqWjKOg8mmb61AGnvHa04nG1dOg9HVXXYmgk0tWLsUbcRn9yF/s2708/20230209_095502.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2708" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi2Mefv1KLm43oqPnAYdkhwpMrv4hJ_6D6y89fs0UMXzuiirRsm9Dp7VXLazLH2P4iDfizOFLzxhVtC1bDsBBGle5-Z7tBcnfymr3b-i5oGgbOoqnGm-74q3-CRX8YvCbNfAxL5jt-AqWjKOg8mmb61AGnvHa04nG1dOg9HVXXYmgk0tWLsUbcRn9yF/s320/20230209_095502.jpg" width="221" /></a></div></span></div><div style="text-align: center;"><span style="font-family: verdana;">The photocathode window was thoroughly cleaned with Acetone and any dust particles were removed using micro-fiber cloth and sticky tape until the glass is absolutely spotless. </span></div><div><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;"><img border="0" data-original-height="1851" data-original-width="1851" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhx7iZvWEs7d-zu8y2ytOR-IOYEactxHaKfpOsaKSfurejgULP_QgV1j6u3TySCa_m3FF-kPnt9K6EoJvylB2xdpWpNqsZoxvBfJFUzh9u_M6HEIxm2qhddrWmdaByDCNouZc5HK1RXfxLmr4ol3L9DywidAgg4zWXOombv7tV2aAF4lUn8MeLPUhp5/s320/20230209_092421.jpg" width="320" /></span><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;">The crystal is a "Soviet Era" 40mm x 40mm CsI(Na). Datecode is June, 1991.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;">CsI is a higher density (4.51g/cm3) scintillation material which makes it more efficient at detecting gamma (better stopping power due to Cesium's higher Z). </span></div><div style="text-align: center;"><span style="font-family: verdana;">Its light output is 85% when referenced to NaI(Tl) but one big advantage of CsI(Na) when compared to CsI(Tl) is that the emission peak matches perfectly the response of Bialkali PMT photocathode at 420nm wavelength. </span></div><div style="text-align: center;"><span style="font-family: verdana;">CsI(Tl) on the other hand is better suited for use with SiPM as its peak is at 550nm and cutoff at 320nm.</span></div><div style="text-align: center;"><span style="font-family: verdana;">CsI(Na) is also much faster scintillator with decay time of 630ns compared to CsI(Tl) at 3.5us which allows for higher rate detection. Not as fast as the NaI(Tl) with 250ns decay.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiin6P88gTPKvVn3o_SrYBi6ZQdPh_p-o7SmNSUwi6F0TnNpjF3rZNcu5lAT9HKI3x2BZ3Chj88JMn8dFAB3vsAGhEitqEOc-FB8FJc_59Kue5rSuhhv7GRsc8g5AZuMKNlIbnBer_vaGAbYkY2kd_2oecH7C4LrubR_W3S4au4Z4ophMIdcW0TTctb/s2772/response.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1282" data-original-width="2772" height="148" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiin6P88gTPKvVn3o_SrYBi6ZQdPh_p-o7SmNSUwi6F0TnNpjF3rZNcu5lAT9HKI3x2BZ3Chj88JMn8dFAB3vsAGhEitqEOc-FB8FJc_59Kue5rSuhhv7GRsc8g5AZuMKNlIbnBer_vaGAbYkY2kd_2oecH7C4LrubR_W3S4au4Z4ophMIdcW0TTctb/s320/response.jpg" width="320" /></a></div>Comparison of the emission peak wavelength and temperature response of both types CsI materials. </div><div style="text-align: center;">The light yield is slightly lower with 41 photons/keV Gamma for CsI(Na) compared to 54 photons per keV Gamma for CsI(Tl) but greater than NaI(Tl) with 38 photons/keV Gamma.<br /></div><div style="text-align: center;"><br /></div></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjKy82SiDuioH5VRFQgtp5e5mQwyrdNtLjoVmrV-ox-q8gxvgunfC23N3QWUNIEweIvT8XjZ0YlBZE-0HgM0dl8GcumNwPXFuxWuj7_4b6qeiRZBU8X79B-Lo6vBiHciczEpBvcT8grOBapmFYNi3zihIaogQBfPW9Jy2s9XQbs05iUbZDdkMG3a3F/s1869/20230209_092302.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1869" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjKy82SiDuioH5VRFQgtp5e5mQwyrdNtLjoVmrV-ox-q8gxvgunfC23N3QWUNIEweIvT8XjZ0YlBZE-0HgM0dl8GcumNwPXFuxWuj7_4b6qeiRZBU8X79B-Lo6vBiHciczEpBvcT8grOBapmFYNi3zihIaogQBfPW9Jy2s9XQbs05iUbZDdkMG3a3F/s320/20230209_092302.jpg" width="320" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">My crystal is absolutely pristine - no significant blemishes, no yellowing, no cloudiness. It is crystal-clear (no pun intended).</div><div style="text-align: center;"> The glass of the optical interface window was cleaned in the same manner as the PMT's photocathode.</div><div style="text-align: center;"><br /></div></span><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrKLouQKN_klVBXbUAHJBPW9eMtfZ5gB1g_S_LGivYqEbEG_DQokmrUJA1S1wD5itWvpXJUN9Fhh7G8ETZRZXTU_2g6K8Bla8E11TpL2DajfPZhCCzomLnXQRFJgxZ01G9DRK4Knp82zFTxa4xCH_nSD_cypNbh2G53Ezwbs7RlS4tkRPg09_Zwod4/s2336/20230209_094609.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2336" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrKLouQKN_klVBXbUAHJBPW9eMtfZ5gB1g_S_LGivYqEbEG_DQokmrUJA1S1wD5itWvpXJUN9Fhh7G8ETZRZXTU_2g6K8Bla8E11TpL2DajfPZhCCzomLnXQRFJgxZ01G9DRK4Knp82zFTxa4xCH_nSD_cypNbh2G53Ezwbs7RlS4tkRPg09_Zwod4/s320/20230209_094609.jpg" width="256" /></a></div><span style="font-family: verdana;">Due to the small difference in diameters between the crystal canister (45mm) and the PMT (51mm), </span><span style="font-family: verdana;">I added a short sleeve from EVA foam around the window area, which will center the crystal during assembly, preventing it from sliding off-center to the PMT. The size difference is very small (~5mm) and there was no need to 3D print a centering collar.</span></div></div><span style="font-family: verdana;"><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKlve7H04gpM132pBwjs2NLorrqomLw8ACOqUgBMFggYs7Rw1RoEHvJOubYdQ86ukIMa61Jj5Mfc3blxIC_xxtwzrSDAeeu3ABt_0CdUHUORGyEy42jRyo2-LZCw6U1y980wWlc3Sq72__QPITfUJMSobt_MiWt0VJsA1eLrC31o8tnVZP19bhto4H/s2718/20230209_095417.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2718" data-original-width="1738" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKlve7H04gpM132pBwjs2NLorrqomLw8ACOqUgBMFggYs7Rw1RoEHvJOubYdQ86ukIMa61Jj5Mfc3blxIC_xxtwzrSDAeeu3ABt_0CdUHUORGyEy42jRyo2-LZCw6U1y980wWlc3Sq72__QPITfUJMSobt_MiWt0VJsA1eLrC31o8tnVZP19bhto4H/s320/20230209_095417.jpg" width="205" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">A drop of high-viscosity (100K cSt) silicone fluid is added as optical interface between the two glass surfaces to minimize reflections and refractions by eliminating the air gap between the two glass windows. The silicone oil's refractive index is around 1.41 which is close to the 1.46 refractive index of the borosilicate glass of the PMT.</div><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlE4oNlJNJZf0vxkYTi8emEnQiRZ2diJ0Djp2f--1Mczc7vw8G0xMfx7-AMawkCxhbyqF7Ewy7X6YDhVQoMCtzpTazMXLqIEJTX3DOG2DKcAiySfzkOFIX0I2A5ohmILaLKjM7exlx2qsIrGlhpXqCMh3o_vRt-y3onHgO7vH4awlrf-0lf8C6qCxS/s1880/20230209_100000.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1880" data-original-width="1480" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlE4oNlJNJZf0vxkYTi8emEnQiRZ2diJ0Djp2f--1Mczc7vw8G0xMfx7-AMawkCxhbyqF7Ewy7X6YDhVQoMCtzpTazMXLqIEJTX3DOG2DKcAiySfzkOFIX0I2A5ohmILaLKjM7exlx2qsIrGlhpXqCMh3o_vRt-y3onHgO7vH4awlrf-0lf8C6qCxS/s320/20230209_100000.jpg" width="252" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">PMT and crystal are put together and the silicone fluid interface is distributed evenly between the two glass surfaces with repeated, overlapping, wide, circular motion until it becomes a very thin and even layer. The extremely high viscosity of this </span>layer and surface tension prevents it from "running" and it will stay permanently in place.</div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnrr34J8jZV2EFGRxzIPgdPVj6xW7B8E5kSs0ms5P3kTVO7OuIJw6phJqpAKlg4KsH70UB2GKE8H6s4UQPpk2Y4oFTyClqmFT9iWl_0q1GQOEtX_hfzh7ydvH2Z_s92Bgr72wq1jkYYpdZ7k0N1XA9P9Xf95QHWE10kbnzLKx8Dje-0svhk8YqdReN/s3323/20230209_100851.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="3323" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnrr34J8jZV2EFGRxzIPgdPVj6xW7B8E5kSs0ms5P3kTVO7OuIJw6phJqpAKlg4KsH70UB2GKE8H6s4UQPpk2Y4oFTyClqmFT9iWl_0q1GQOEtX_hfzh7ydvH2Z_s92Bgr72wq1jkYYpdZ7k0N1XA9P9Xf95QHWE10kbnzLKx8Dje-0svhk8YqdReN/s320/20230209_100851.jpg" width="180" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">Strips of vertical electrical tape are used to pull together both, PMT and Crystal with some tension. The tape is stretched during application, and it exerts constant pressure between the two parts ensuring a firm contact. With this small diameter PMT 4 long strips (which loop under the crystal) are sufficient.</span></div><div style="text-align: center;">Both, crystal and PMT are then wrapped multiple times, around, with special focus on the interface zone so it becomes one tight package.</div><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQBWagBsOAUvHpXCuvnThR9CQnMTUc1zq0xvMsELGaiHBstoE8fbajfpbXN31wfWxe57AL_xE9S2iFT-7gXCBja6pJhIcIPUcvg0HYom3CyWcg-mS_VuXLZPEVT2bWU_e7vtsGZOewnDQvgb-nbvBohxykl7_fQ00Wfg1J4m996Tx5pn2IkJ-Snxrd/s3435/20230209_103345.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1601" data-original-width="3435" height="149" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQBWagBsOAUvHpXCuvnThR9CQnMTUc1zq0xvMsELGaiHBstoE8fbajfpbXN31wfWxe57AL_xE9S2iFT-7gXCBja6pJhIcIPUcvg0HYom3CyWcg-mS_VuXLZPEVT2bWU_e7vtsGZOewnDQvgb-nbvBohxykl7_fQ00Wfg1J4m996Tx5pn2IkJ-Snxrd/s320/20230209_103345.jpg" width="320" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">After completely wrapping the assembly with multiple layers of electrical tape, I added a sleeve of EVA (Ethylene-Vinyl Acetate) foam to serve as mechanical shock protection and thermal insulation for the assembly. EVA foam is a very dense closed-cell foam and does great job for both applications.</span></div><div style="text-align: center;"><span style="font-family: verdana;">The front face of the crystal is also protected by a disk of EVA foam, glued to the crystal's foam sleeve. </span></div><div style="text-align: center;"><span style="font-family: verdana;">Needless to say, the assembly is 100% light-proof.</span></div><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgmGtc93cTwvC4vnRLlDcTLfGRQdtlhFmAQmXWIewkfFZE4ClNljbLZ6-RB4HETu2bp0Bj0yFsl8pTVsLrR9ueT6dtPnS91quSsJ7hYDScGYsDKus6bnSiIXh-kCaL6JXnnNMCAlKWP5gGw8lW_XW_kTukD-LjH06tLRdd0x7yrD5MsuGvjq98E4VS/s3444/20230209_105417.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1868" data-original-width="3444" height="174" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgmGtc93cTwvC4vnRLlDcTLfGRQdtlhFmAQmXWIewkfFZE4ClNljbLZ6-RB4HETu2bp0Bj0yFsl8pTVsLrR9ueT6dtPnS91quSsJ7hYDScGYsDKus6bnSiIXh-kCaL6JXnnNMCAlKWP5gGw8lW_XW_kTukD-LjH06tLRdd0x7yrD5MsuGvjq98E4VS/s320/20230209_105417.jpg" width="320" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">The magnetic / electrostatic shield is added as a two-turns sleeve of special Mu-Metal sheet, spot-soldered closed, and the grounding wire is then soldered to the sleeve. The sleeve overlaps the photocathode area and into the crystal canister by about 5-7 mm.</span></div><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzRLEz6h67r0DT4OGcRnbZpN0HGBpP66ER9UJXt2w43Ijq1YJOs5Q5uIk8_V9BE9D-7y6ybVUVD5JO3qSTMDpSWk_UKVy6X2vtKoe7Z0wamuPPuKmpdR9TF94G-GRaGh_PfBlr3JsISePlp96AJuY_EkkV7ilqvI1ZDIwmy3og6mvbmd9cdlK-2xwC/s3786/20230209_110758.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1868" data-original-width="3786" height="158" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzRLEz6h67r0DT4OGcRnbZpN0HGBpP66ER9UJXt2w43Ijq1YJOs5Q5uIk8_V9BE9D-7y6ybVUVD5JO3qSTMDpSWk_UKVy6X2vtKoe7Z0wamuPPuKmpdR9TF94G-GRaGh_PfBlr3JsISePlp96AJuY_EkkV7ilqvI1ZDIwmy3og6mvbmd9cdlK-2xwC/s320/20230209_110758.jpg" width="320" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">Second EVA foam layer for even more shock protection of the glass-envelope PMT goes on top of the magnetic shield.</span></div><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhn0au9DhZlaCDDvevWkkJarYS_U3tfLYImV06KcjP7xqZ-grZQfXNm5Lk6-b5mDdfNr-PIwI5xHOXJoASNjt5eYto-r-F1V9JxGjYSqD64SnseshAW7iGhv72xym5tgmpbOSlU4ncRrAnHXKg-PL0GNcjybY7CBFvVlSuhfrSXI1qle956U-OZ91UU/s3129/20230209_114532.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1868" data-original-width="3129" height="191" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhn0au9DhZlaCDDvevWkkJarYS_U3tfLYImV06KcjP7xqZ-grZQfXNm5Lk6-b5mDdfNr-PIwI5xHOXJoASNjt5eYto-r-F1V9JxGjYSqD64SnseshAW7iGhv72xym5tgmpbOSlU4ncRrAnHXKg-PL0GNcjybY7CBFvVlSuhfrSXI1qle956U-OZ91UU/s320/20230209_114532.jpg" width="320" /></span></a></div><p style="text-align: center;"><span style="font-family: verdana;">After completing the entire assembly, the final protective layer of heat-shrink tubing is applied. </span></p><p style="text-align: center;"><span style="font-family: verdana;">This is probably the most critical and dangerous part of the assembly process as overheating the crystal can easily cause it to crack. Crystal temperature should not be increased too rapidly. Heat was applied in short burst (with cooling time between them), which allowed the heat-shrink to heat up rapidly but not to transfer a lot of heat at once to the crystal.</span></p><p style="text-align: center;"><span style="font-family: verdana;">Heat-shrinking is not "a must" but provides a nice finish, serves as an additional protective, abrasion / scratch resistant layer and keeps both components - crystal and PMT firmly together.</span></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtGEh70N4HP7PKOCOjYN7UzQ1FW-kdE0yAqdbS92no4VkwLcqDKa_LLqoINc5XV53DU-eYVtqIhzWanPtiZv_BJCDKzh8x00tXde5G_Dbe02-gA3olJsIexu-leS4YP_KwPF-lPE7svhhtl7rt_WW_f-hvCz4C4qtFhMD42YwJERS66v6qbR6NH0wA/s1742/CsINa_detector.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="954" data-original-width="1742" height="175" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtGEh70N4HP7PKOCOjYN7UzQ1FW-kdE0yAqdbS92no4VkwLcqDKa_LLqoINc5XV53DU-eYVtqIhzWanPtiZv_BJCDKzh8x00tXde5G_Dbe02-gA3olJsIexu-leS4YP_KwPF-lPE7svhhtl7rt_WW_f-hvCz4C4qtFhMD42YwJERS66v6qbR6NH0wA/s320/CsINa_detector.png" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">Just as expected, the resolution is not bad at all and spectrum looks pretty good! </div></span><p></p><p style="text-align: center;"><span style="font-family: verdana;">Running the detector on 600V PMT Bias. For Cs-137 at 662keV resolution is 6.2% FWHM. </span></p><p style="text-align: center;"><span style="font-family: verdana;">Theremino's algorithm for automatic estimation of the FWHM resolution seems to be a bit on the conservative side so a more realistic value would be actually around 6.0% - not too shabby for a 30-year-old, Soviet Era crystal I must say.</span></p>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com2tag:blogger.com,1999:blog-5557902467288736826.post-70521211725176675212023-03-07T12:25:00.011-05:002023-03-13T12:17:11.463-04:00Complete DIY XRF Setup<p><span style="font-family: verdana;">My DIY XRF setup is finally complete - it is comprised of an Amptek X-123 detector using the proprietary Amptek </span><span style="font-family: verdana; text-align: center;">25 mm<span style="font-size: x-small;">2</span> / 500 μm</span><span style="font-family: verdana; text-align: center;"> </span><span style="font-family: verdana; text-align: center;">Si-PIN X-Ray detector element </span><span style="font-family: verdana; text-align: center;">(model FSJ32MD-G3SP), Amptek Pre-Amplifier and DP5 DPP /MCA.</span></p><p><span style="font-family: verdana; text-align: center;">Details about the detector are in <a href="http://blog.kotarak.net/2021/04/my-xrf-setup-part-2.html">THIS post</a>.</span></p><p><span style="font-family: verdana; text-align: center;">On the exciter side, in the past, I have used X-Rays from an Am-241 source (59.54keV). Unfortunately, there is no exempt quantity or a way to obtain high activity, pure Am-241. The ones used in modern household smoke detectors are only 0.9 uCi (unless obtained from the old Pyrotronics industrial smoke detectors with up to 80uCi) but still have the Am-241 mixed and pressed into Gold and Silver foil which has parasitic emissions of the said metals in addition to the Am-241 decay product - usually a fairly strong Np La line emission (from Np-237 decay product). The Neptunium La-line is observed even with recently created Am-241) La at 13.95keV.</span></p><p><span style="font-family: verdana; text-align: center;">I decided to switch over to an X-Xay Tube where the emission can be controlled, the spectrum is uniform with the exception of the XRF emissions from the target material but this is normally a single metal.</span></p><p><span style="font-family: verdana; text-align: center;"> I am using Moxtek Magnum series transmission X-Ray tube with Tungsten target - 10W total electrical power (-50kV / 200 uA) controlled by an X-ray source controller of my own design.</span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgELIqMOPRrzADmnYSx_vcD3dYmO57ZHfMI_TbFluYtMhOtgv2De43-OT-B81GisZq807ftT-HCsuqSx_cxvNdK3PQIVsn1GmOgc1Db6MiqTTtL0QBEveKI9nJ3Vbx-tPTMnQu2mv9xcpJ-DtR28YnaLo4NFcXSjpYzSdzRVwaZL1F1XKtWZbfNzdDB/s4000/20230306_135337.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1868" data-original-width="4000" height="149" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgELIqMOPRrzADmnYSx_vcD3dYmO57ZHfMI_TbFluYtMhOtgv2De43-OT-B81GisZq807ftT-HCsuqSx_cxvNdK3PQIVsn1GmOgc1Db6MiqTTtL0QBEveKI9nJ3Vbx-tPTMnQu2mv9xcpJ-DtR28YnaLo4NFcXSjpYzSdzRVwaZL1F1XKtWZbfNzdDB/s320/20230306_135337.jpg" width="320" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">The X-Ray tube is placed inside a Lead shield. The aluminum box on the right-top in this picture is the detector enclosure, housing the detector element, preamp, power supply and the Amptek DP5 Digital Pulse Processor.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNuKUB68P8HmyjLzHjWzyVOWxK9SyOk05jqgxZYwIouFBh6N6cEk6CRDDkkusl-YR2quTQc09jAHqjvimjjINr5DTHBs0KqbJSZpwjexsC79kjYvOcuW2LYkBtJEA7Bdc-yTCrlVofdFReeabQNmmgqSHWWRfK5JWsFkhSQIdARqDDZWhHKwJ_fU0Q/s4000/20230306_135034.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1868" data-original-width="4000" height="149" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNuKUB68P8HmyjLzHjWzyVOWxK9SyOk05jqgxZYwIouFBh6N6cEk6CRDDkkusl-YR2quTQc09jAHqjvimjjINr5DTHBs0KqbJSZpwjexsC79kjYvOcuW2LYkBtJEA7Bdc-yTCrlVofdFReeabQNmmgqSHWWRfK5JWsFkhSQIdARqDDZWhHKwJ_fU0Q/s320/20230306_135034.jpg" width="320" /></span></a></div><span style="text-align: center;"><div style="text-align: center;"><span style="font-family: verdana;">This is my test setup while doing XRF on a piece of copper foil for initial Energy Calibration.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQQUd0gpzh_zaWGpB1bDi2Y7uu43Wb37Q6pB0efXSA3o9ZKgc5RFS7cu2-G-3T1NJJeYW_A3TChgR8-ANcgRjN9KJ9VmJdEu3JteMYyfudUdOJgwiE8wNUMmijHNcYm6-Aa7lYCGxmdqTV4UMC_BB9fN9hHMO-vS_jmfuyH225PIvk_bmhLmefePrn/s3429/20230306_135008.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3429" height="174" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQQUd0gpzh_zaWGpB1bDi2Y7uu43Wb37Q6pB0efXSA3o9ZKgc5RFS7cu2-G-3T1NJJeYW_A3TChgR8-ANcgRjN9KJ9VmJdEu3JteMYyfudUdOJgwiE8wNUMmijHNcYm6-Aa7lYCGxmdqTV4UMC_BB9fN9hHMO-vS_jmfuyH225PIvk_bmhLmefePrn/s320/20230306_135008.jpg" width="320" /></a></div><span style="font-family: verdana;">The aluminum box in the center of the picture is the X-Ray tube's high-voltage power supply module. It is a high-frequency switching supply with a very easy to work interface - 3 output channels (2 analog and 1 digital) and 3 input channels (2 analog and 1 digital) + 12V main power. The supply is very efficient and the current draw is around 1.5A at maximum power.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwwDwgpSyc4bUOHbrEmIcI3bfL1kv2jo3ESJr2PKOCKLJXnFBLc-xW7lyU8wBVQGRgLi4Upjzr_eB9BQJOABUPrvXWwUrfQ4voF5Witw4-iilIq41BIDuJxuw4cdM5XKvmOfhFD7sQpJvjG9OzO9If5_oz60br69XnTgC3Cnf8rK7foD1F6AvZhonI/s2572/20230306_142122.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2572" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwwDwgpSyc4bUOHbrEmIcI3bfL1kv2jo3ESJr2PKOCKLJXnFBLc-xW7lyU8wBVQGRgLi4Upjzr_eB9BQJOABUPrvXWwUrfQ4voF5Witw4-iilIq41BIDuJxuw4cdM5XKvmOfhFD7sQpJvjG9OzO9If5_oz60br69XnTgC3Cnf8rK7foD1F6AvZhonI/s320/20230306_142122.jpg" width="232" /></a></div><span style="font-family: verdana;">The X-Ray source aperture and detector at almost 90 degrees so the X-Rays are skimming the surface of the specimen.</span><br /><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5cLgoZxdBE95dTZFT4tKRxVBBJ9SLLy4Pdni_zYC1QdZ4JPHMz2-CGxah8JC1eLNUz0YeiIZ9f88urEgSmFOHA_rNmRadg7Hti1bUdcLa6HiukYXgdHzp3vhLLbWWFFfp_-MRc8XS9ZXr1trMlf6VKBd42xhW83yfcbFB4LNk45lk5TQQVoeLYtT4/s2525/COPPER.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1611" data-original-width="2525" height="204" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5cLgoZxdBE95dTZFT4tKRxVBBJ9SLLy4Pdni_zYC1QdZ4JPHMz2-CGxah8JC1eLNUz0YeiIZ9f88urEgSmFOHA_rNmRadg7Hti1bUdcLa6HiukYXgdHzp3vhLLbWWFFfp_-MRc8XS9ZXr1trMlf6VKBd42xhW83yfcbFB4LNk45lk5TQQVoeLYtT4/s320/COPPER.jpg" width="320" /></a></div><span style="font-family: verdana;">This is the first XRF of Copper foil with the new source - the Ka line is at 8.05keV and to the right the Kb-line is at 8.90keV. </span></div><div style="text-align: center;"><span style="font-family: verdana;">I still need to adjust the detector Peaking Time and Flat Top Time as well as the Slow and Fast detector thresholds - currently I have over 99% of Dead time due to the current settings intended for low X-Ray flux source.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;">My X-Ray Source Controller works flawlessly, and I am really happy with the end-result.</span></div></span><p></p>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-55825519208611945732023-02-25T21:10:00.025-05:002023-09-13T03:29:44.699-04:00X-Ray Source Controller for MOXTEK and AMPTEK Mini X-Ray tubes<p> <span style="font-family: verdana;">I needed controller for the Magnum series 50kV / 10W MOXTEK X-Ray source. As it turns out the controller, once sold by MOXTEK is no longer available (discontinued due component availability) and the Moxtek salesperson told me - "We expect customers to develop their own controllers". </span></p><p><span style="font-family: verdana;">This was not a big deal - their FTC-200 controller has very basic functionality anyways, so I went ahead and developed my own design to control the tube.</span></p><p><span style="font-family: verdana;">One of my design goals is to have a stand-alone unit with no PC required. I don't want to fumble with numerous applications while doing XRF and prefer to have a piece of hardware with actual buttons and dialls to adjust X-ray tube parameters and operate it.</span></p><p><span style="font-family: verdana;">I was pleasantly surprised to find out that the AMPTEK Mini-X2 tube uses the same electrical interface as MOXTEK so my controller will work for AMPTEK Mini-X2 just as well.</span></p><p><span style="font-family: verdana; text-align: center;">My design is based on the nRF52840 System-on-a-Chip (SoC) using Cortex M4F processor and employs 6 control channels as required by the x-ray source interface - 4 Analog and 2 digital channels. Of these 6, there are 2 Analog outputs (driven by 12-bit DACs), used for setting up tube's HV and Emission Current parameters, 1 digital output (5V TTL signal) to turn the source ON / OFF. There are also 2 Analog inputs (sampled with 12-bit ADCs) to monitor the x-ray tube's working parameters as they are returned by the Moxtek HV PS module and a digital input (5V TTL signal) to report when the beam is on and stable (Filament fully heated). </span></p><p><span style="font-family: verdana; text-align: center;">I had to employ Level shifters as the nRF52840 is a 3.3V chip and the MOXTEK module has 5V TTL levels for the digital signals. Furthermore, the set ranges on the Analog output channels are 0-to-4V so I had to use the 4.096V internal DAC reference voltage which means the DAC must be powered with 5V Vdd. (in reality, the reference is 2.048V and the output op-amp buffer uses 2X gain, but still 5V DAC power is required) </span></p><p><span style="font-family: verdana; text-align: center;">For the Analog inputs, I used voltage dividers to bring down the Monitor channel voltages in the range of 0-to-3VDC and used the built-in ADC reference of 0.6V with gain of x5.</span></p><p><span style="font-family: verdana; text-align: center;">There is also 5th Analog Input channel, internal to the controller, with its own voltage divider, used to monitor the Low-Voltage Main Input Power and to inhibit controller operation if the controller's and tube's input voltage is not within the allowed range. </span></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjcGVd3q6k0bvrzecB-3zlFSyAvL1NXZiVkGVhXV04XGZjkkl1E7a0aizeT7t7MOO1Qg2C9F3YiwoPujcZbpSZhcteyzBJZhnKQdDHK71zqSK5-bbgGd4GOGq48zF0ExVDA3JyqWWXSpGAHaAnjS-xqN2SWVQ43k7Bcz0hvnFB7hlI2KCTyl_VH-sI/s2345/20230224_123246.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2345" height="255" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjcGVd3q6k0bvrzecB-3zlFSyAvL1NXZiVkGVhXV04XGZjkkl1E7a0aizeT7t7MOO1Qg2C9F3YiwoPujcZbpSZhcteyzBJZhnKQdDHK71zqSK5-bbgGd4GOGq48zF0ExVDA3JyqWWXSpGAHaAnjS-xqN2SWVQ43k7Bcz0hvnFB7hlI2KCTyl_VH-sI/s320/20230224_123246.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">OSH Park service delivered again beautiful, high-quality PCBs. The ordering process is very simple and a pure joy - I almost feel sorry I don't have more PCB projects to order. </div><div style="text-align: center;">The PCB design was done with Autodesk Eagle but I am not big fan of what Autodesk is doing with Eagle and very likely to switch over to KiCad in the near future.</div></span><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1AoDFv7vKxs0ZnfqkYItb790InW965rvpzbRCSQClIzy5URHOmaDFt4kEHfy9X23qVzX1GXD-I_-MtK8qNR3G1wnZFZDlZiCkRtfp7o_u-JAJTCQsKORWaHQkds-b8qk-x0KHSiqGbK7GBog-UEQ6hXDx3_O6VVfaXPSJAVXiYAdhkB1cNd7l-kX8/s3314/20230224_123706.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3314" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1AoDFv7vKxs0ZnfqkYItb790InW965rvpzbRCSQClIzy5URHOmaDFt4kEHfy9X23qVzX1GXD-I_-MtK8qNR3G1wnZFZDlZiCkRtfp7o_u-JAJTCQsKORWaHQkds-b8qk-x0KHSiqGbK7GBog-UEQ6hXDx3_O6VVfaXPSJAVXiYAdhkB1cNd7l-kX8/s320/20230224_123706.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">The assembled and ready X-Ray Source controller - XTC-2000 (a.k.a. "X-Ray Tube Commander 2000" :-) </div><div style="text-align: center;">(Chat GPT suggestion :-)</div><div style="text-align: center;"><br /></div><div style="text-align: left;">Using a rotary encoder with a pushbutton makes the UI really quick and intuitive. The button (knob-press) is used to enter adjustment mode and the user can dial the whole number and the tenths after the decimal point for each parameter separately. After entering Set mode, the encoder's push-button scrolls through different cursor positions and spining the dial changes the value. </div><div style="text-align: left;">The encoder is equipped with its own microcontroller (Atmel SAM D09) which takes care of all of the quadrature input stuff - counts, phase-detection, timing, etc. and just reports the actual tick count over I2C bus to the MCU. This makes it really fast and easy to use and I can reset the tick counter with a command if needed.</div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpI5-MjX4Yuw6PdG_F41vaI7o6paLfdwlPnBGvSsE09xCIE2bwzmp0yoO-WSIRVljsVS8eYj6Rz2saRDsxIktdyUMcbmKiPUk0W78XQWaOeXfHplkbqivCdrIVMAQKuqi3iFeayxQbt2m5zjSxV4qJ2S4ciQ5O1Op11JPnMdUlhw7BcmZyfkymzJH8/s3269/20230225_161255.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3269" height="183" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpI5-MjX4Yuw6PdG_F41vaI7o6paLfdwlPnBGvSsE09xCIE2bwzmp0yoO-WSIRVljsVS8eYj6Rz2saRDsxIktdyUMcbmKiPUk0W78XQWaOeXfHplkbqivCdrIVMAQKuqi3iFeayxQbt2m5zjSxV4qJ2S4ciQ5O1Op11JPnMdUlhw7BcmZyfkymzJH8/s320/20230225_161255.jpg" width="320" /></a></div><div style="text-align: center;">The complete and working controller during bench-testing and DAC/ADC non-linearity compensation and alignment. The white (unpopulated in this picture) 4-pin JST connector near the encoder is AUX I2C expansion connector, used for the remote temperature sensor.</div><div style="text-align: center;"><br /></div><div style="text-align: left;">Currently, the code is fairly small (~1800 lines only) yet it is pretty complete and mature and the core functionality is all done and bug-free thus "Version 1.0" designation is warranted. </div><div style="text-align: left;">In the unlikely event of some commercial interest I might write a menu system for setting up various tube types, internal parameters and calibration values, but even at this stage, XTC-2000 has more features, better functionality and better ergonomics than both, the discontinued Moxtek FTC-200 controller and the entirely software-controlled Amptek controller. </div><div style="text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnN9QK6C0IG0NQV3yLfpdfulGw2dZshzq3Ar8_GG1gcTnM1cMS9XxPXBQhDmGzokEWbKtOg0EqePgBxTn0yUP_hDlcsr2uUufi6HzpjTZbkoSmkAfboTgVFhfrrXkb1323MDl3n75EdEPdDt3dG9EMjeWEP_wQwXTuJI5HY_1poBjPMtbbYUYfc6LE/s2600/temp_Sensor.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1733" data-original-width="2600" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnN9QK6C0IG0NQV3yLfpdfulGw2dZshzq3Ar8_GG1gcTnM1cMS9XxPXBQhDmGzokEWbKtOg0EqePgBxTn0yUP_hDlcsr2uUufi6HzpjTZbkoSmkAfboTgVFhfrrXkb1323MDl3n75EdEPdDt3dG9EMjeWEP_wQwXTuJI5HY_1poBjPMtbbYUYfc6LE/s320/temp_Sensor.jpg" width="320" /></a></div><div style="text-align: center;">As part of the safety and tube's health features, I added temperature sensing and monitoring using MCP9809 chip.</div><div style="text-align: center;"><br /></div><div style="text-align: left;">While designing the PCB, I foresaw that having an extra I2C bus connector for future expansion might come handy so I added one to the board layout.</div><div style="text-align: left;">The sensor I am using is MCP9808 - a very accurate and precise chip with I2C interface. Resolution is actually much better than 0.25°C but for my purpose 1° Celsius is completely sufficient.</div><div style="text-align: left;">The controller constantly monitors the temperature of the tube and it will shut it off if temperature exceeds +60°C and until cools down below +55°C. The sensor presence is auto-detected on startup - if the cable is not plugged in, the controller will work normally, without any limitations.</div><div style="text-align: left;">The critical part here is the connection cable between the controller and the MCP9808 breakout board - the cable must be fully shielded due to the proximity to the tube's HV cables and must be of very low capacitance as the I2C bus does not allow for high capacitance on the signal lines or the useable bus speed will begin to drop. At 70cm cable length the sensor works just fine. The cable I used was foil-shielded 4-conductor USB cable.</div><div style="text-align: center;"><br /></div><div style="text-align: left;">The last thing currently pending on my development list is a suitable enclosure.</div></span>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-10517324580945786892023-01-19T18:28:00.013-05:002023-09-15T01:25:31.537-04:00XRF Exciter source using a Moxtek Miniature X-Ray Tube<p><span style="font-family: verdana;"> I am working on a new XRF Exciter source, employing a pretty cool miniature, ceramic, 10W X-Ray tube with Tungsten target by Moxtek (MAGNUM series). This source will deliver an immensely higher X-Ray flux compared to the Am-241 source I've been using, thus cutting down on the integration time during XRF analysis and bringing out peaks hiding in the noise.</span></p><p><span style="font-family: verdana;">The Moxtek X-Ray tube comes with a High-Voltage Power Supply module which allows for control of both, the tube voltage (-10kV to -50kV range) and the tube's emission current (0 to 200 uA). The maximum electrical power is 10W into the tube - <a href="https://moxtek.com/wp-content/uploads/pdfs/TUB-DATA-1005-50kV-Cable-with-MAGNUM-X-ray-Source-Rev-L.pdf">here are the specs</a>.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6h_ExnqJsmTAo5yIoZsNC5zJATGPI3Il0a1GrN-fGGLfUt-OSL6G0_tDqfwDojhLGvtcvPV6QZerNCC9_FjAyApt5zjFokySyLvWWVoJVdebbfiYwjxfKtAxZ7ECsOhVb673aC648Pf9uDwqFWv6bhKFqlZsXCIDyZwGUU4UE0oaPmFfNMDs03OLk/s2575/20230117_102224.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2575" height="232" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6h_ExnqJsmTAo5yIoZsNC5zJATGPI3Il0a1GrN-fGGLfUt-OSL6G0_tDqfwDojhLGvtcvPV6QZerNCC9_FjAyApt5zjFokySyLvWWVoJVdebbfiYwjxfKtAxZ7ECsOhVb673aC648Pf9uDwqFWv6bhKFqlZsXCIDyZwGUU4UE0oaPmFfNMDs03OLk/s320/20230117_102224.jpg" width="320" /></a></div><p style="text-align: center;"><span style="font-family: verdana;">The brass housing of the X-Ray tube with the beryllium window aperture and the two high-voltage supply cables. The tube is in a Grounded Anode configuration and the two cables deliver both, High-Voltage to the Cathode and power to the filament. The brass housing is massive enough to dissipate plenty of heat. In its final configuration, the tube will mounted inside of 1+" thick lead shielding as some X-rays are generated in all directions besides the collimated main beam. These X-Rays are much attenuated but still a radiation hazard so proper shielding is mandatory.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig7YAwhHMgbdRGnbI5Pv5bttvEAlgKtaJ77gyfeOsMUNsvenHBVz8kGgMT-bJoZX38HGXjON6TD7IVOmdl548SxNU4bS_C5wuD6vpLcGHk4M5SQSqJjO12zul8JB9687ak9H0fGsTmkhN70vdMyUEC1nmE5QMXb2Q2mLcofWH0agv-EscuKOZu9AzY/s3659/20230117_102115.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1762" data-original-width="3659" height="154" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig7YAwhHMgbdRGnbI5Pv5bttvEAlgKtaJ77gyfeOsMUNsvenHBVz8kGgMT-bJoZX38HGXjON6TD7IVOmdl548SxNU4bS_C5wuD6vpLcGHk4M5SQSqJjO12zul8JB9687ak9H0fGsTmkhN70vdMyUEC1nmE5QMXb2Q2mLcofWH0agv-EscuKOZu9AzY/s320/20230117_102115.jpg" width="320" /></a></div><p style="text-align: center;"><span style="font-family: verdana;">My test setup. The HV PS has a very neat and straight-forward interface for controlling the tube's operational parameters of the tube. It is also very efficient when it comes to power - it requires 9V to 12V DC and about 1A of current. The efficiency is a little over 80% - around 12W input power which is fantastic.</span></p><p style="text-align: center;"><br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghwiK3IBrhflVwzLEjqhibWlyA41FJBUr3077fUVgp44lqglf2n8CUW1Snc45uavJSMGnYxOi02a7ShwyhDfCQ-cNwnpV5I3Nz0BIEfFe3DDryhQzLQF1DCnWHUKdJJf3UOZbHegg8szzwdESZsGxgtRpl5_tVbUDL8RdoIRPSi7MBZr26IAyUn9Ev/s3369/20230117_102017.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3369" height="177" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghwiK3IBrhflVwzLEjqhibWlyA41FJBUr3077fUVgp44lqglf2n8CUW1Snc45uavJSMGnYxOi02a7ShwyhDfCQ-cNwnpV5I3Nz0BIEfFe3DDryhQzLQF1DCnWHUKdJJf3UOZbHegg8szzwdESZsGxgtRpl5_tVbUDL8RdoIRPSi7MBZr26IAyUn9Ev/s320/20230117_102017.jpg" width="320" /></a></div><br /><p style="text-align: center;"><span style="font-family: verdana;">While I am designing and prototyping the X-Ray tube controller (more on this later), just for a quick testing I was driving the tube with my 3-channel power supply in a rather "manual fashion" - Ch.1 is the main power, Ch.2 controls the HV - 0.8V to 4V are scaled to -10kV to -50kV range and Ch.3 sets the beam's current - 0 to 4V are scaled to 0-200uA range.</span></p><p style="text-align: center;"><span style="font-family: verdana;">The tube's module returns monitor signals - voltages with the same exact scaling factors as the control voltages in order to monitor the actual HV and Current. A TTL level signal controls the beam ON/OFF and there is a FILAMENT READY return signal from the HV PS when the filament is heated, and the beam is ON and stable.</span></p><p style="text-align: center;"><span style="font-family: verdana;">One important requirement is that the beam should not be turned ON sooner than 2 seconds after it has been turned OFF to prevent damage to the tube's filament. For the same reason the tube should be turned ON for a minimum of 1 second and no less than that - all these will be part of my design goals for the controller.</span></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgP8jDs0bbyBGXM3yP0YsFij8bwrTHNlsw5XzLRR_wT_cxC444ep17a6RYh050hauC-ewTtXvJSpG9SzazXpnkjAAqXxAcAPFPjpacSbswoC5dSFXx_AKiJ_F73fBstfEuhIuDHK6FzGJCwTDy1gQTW71fHp3tHRW2WpajBLpZbYOivicZv59czrxPP/s3581/20230124_152452.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3581" height="167" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgP8jDs0bbyBGXM3yP0YsFij8bwrTHNlsw5XzLRR_wT_cxC444ep17a6RYh050hauC-ewTtXvJSpG9SzazXpnkjAAqXxAcAPFPjpacSbswoC5dSFXx_AKiJ_F73fBstfEuhIuDHK6FzGJCwTDy1gQTW71fHp3tHRW2WpajBLpZbYOivicZv59czrxPP/s320/20230124_152452.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">Prototyping the X-Ray tube controller - using nRF52840 MCU with ARM Cortex M4F, 24LC32 EEPROM for storing configurations, 12-bit MCP4728 Quad DAC for Tube control voltages, large SHARP Memory display (400x240), bi-directional level shifter, Non-Latching Relay, MCP 9808 temperature sensor and a nifty I2C Rotary Encoder breakout.</div><div style="text-align: center;">There are various other components - voltage dividers, voltage regulator, power conditioning, buzzer, pull-up and pull-down resistors, etc. located on the controller board - I designed the board with some thru-hole components so I can easily continue the development once I have the boards in hand and swap components as needed.</div></span><span style="font-family: verdana;"><br /></span><p></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiAimtNuL0gH5sX-ndgmQ-W8qzREtL2U28CIHjjDGsZwhmzEj4GXETot_qRFKFqTaFwOJAcAdiwuTyi3JB52P5Ych2W_ROrq-TPn81GD5KIMmXAOCrbDnnj_G3tn91f4ub3CLTyJnIWZGjTLD45DAs0WAMV_byevKnG2h-vQ_PEEaFkXQb5IJecQ2x1/s2412/20230124_085827.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2412" height="248" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiAimtNuL0gH5sX-ndgmQ-W8qzREtL2U28CIHjjDGsZwhmzEj4GXETot_qRFKFqTaFwOJAcAdiwuTyi3JB52P5Ych2W_ROrq-TPn81GD5KIMmXAOCrbDnnj_G3tn91f4ub3CLTyJnIWZGjTLD45DAs0WAMV_byevKnG2h-vQ_PEEaFkXQb5IJecQ2x1/s320/20230124_085827.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">Controller's User Interface</div><div style="text-align: center;">Top of the screen is the Status display, temperature reading (when sensor is plugged in) and the current timer display. Second section, below, is the Mode selector and Timer Selector display - it also shows the Last Run Log and calculated X-Ray tube power. Third section is the X-Ray tube's Parameter (S) Set configuration where the user can dial in voltage in -5kV to 50kV range (0.1kV steps) and Tube's current 1uA to 200uA (0.1uA steps). Bottom part is the (M) monitor display showing the return signals from the tube's power supply module - sampled with 2x 12-bit ADCs. </div><div style="text-align: center;">All set parameters are persistent - stored in EEPROM and automatically loaded on startup. There are also two user-configurable Presets with Tube parameters for quick switching between different sets of values for different experiments. I might increase the number of presets to 3 eventually.</div></span><p></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZ27EToAFoG04jB6tZzuQacbLFKIH6bAz4mmsxZojvWs5CkV-vUhKsc-W8Sgp6cnIxSgg03mhe_kgeeBJqjBR8JeUCF15HzQMwVt_7u-gG9xpkE4LL8jecN4kXnCGdu0qNb2QrNM11z3Gwmk6OQL7Gs4ls1kzMz09cqSqilu20kEVYszG2E1QFm21M/s2492/20230124_090642.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2492" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZ27EToAFoG04jB6tZzuQacbLFKIH6bAz4mmsxZojvWs5CkV-vUhKsc-W8Sgp6cnIxSgg03mhe_kgeeBJqjBR8JeUCF15HzQMwVt_7u-gG9xpkE4LL8jecN4kXnCGdu0qNb2QrNM11z3Gwmk6OQL7Gs4ls1kzMz09cqSqilu20kEVYszG2E1QFm21M/s320/20230124_090642.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">There are 3 operational modes - MOMENTARY when beam is ON while the OPERATE button is pressed and turned OFF when released. </div><div style="text-align: center;">The second mode is TOGGLE - pressing the OPERATE button turns ON the beam and starts a count up timer. Second press of the OPERATE button turns OFF the beam. Sequential ON/OFF will integrate the beam time in the "Last Run time" until a RESET action is executed. </div><div style="text-align: center;">The third mode is COUNTDOWN timer - the user can dial desired beam time and OPERATE button STARTS/PAUSES the countdown. The X-Ray beam is turned OFF when the timer expires but it can be PAUSED, STOPPED or CANCLED at any time. The user can also spin the rotary encoder to add or remove time from the timer while the beam is ON.</div></span><p></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGfjuOsrohUML__Wgfsc2yZz3W9uvRA1acYhMxzbTO6N09sLcP_wtKgB6lv-Xr0UYiLPqwM-PPaVd1WLe7TlsKi6Qn60a6lIRJ2hUiOttIO9sxDWRmCDA7ozIYv-Iyorb4NZGETFhsID3qaxNsCEW_H_q_djUPaJ29MGpTlYf0h432KnB-eQARHIcT/s2377/20230124_090218.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2377" height="251" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGfjuOsrohUML__Wgfsc2yZz3W9uvRA1acYhMxzbTO6N09sLcP_wtKgB6lv-Xr0UYiLPqwM-PPaVd1WLe7TlsKi6Qn60a6lIRJ2hUiOttIO9sxDWRmCDA7ozIYv-Iyorb4NZGETFhsID3qaxNsCEW_H_q_djUPaJ29MGpTlYf0h432KnB-eQARHIcT/s320/20230124_090218.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">I have added many safety features!</div><div style="text-align: center;"> When the beam is turned OFF there is a 2 seconds blackout period while the filament is cooling. During this time the beam cannot be re-engaged. It is not possible also to run the tube for less than 1 second - if any such attempt is made, the controller will automatically "pad" the time for a total of 1 second. There is an INTERLOCK detection feature which inhibits any operation unless the interlock switch on the door/lid of the enclosure is closed or overridden with a key. In COUNTDOWN and TOGGLE mode, pressing on the TIMER RESET/MODE button or the Rotary Encoder button acts as an EMERGENCY SHUT-OFF.</div><div style="text-align: center;"> In TOGGLE mode there is also Timeout feature which will turn off the tube after a period of time if left unattended. The controller also constantly monitors the Low Voltage supply and disables the tube if under-voltage condition occurs. Tube temperature is monitored with an external sensor attached to the tube housing and the tube is turned OFF if temperature reaches 60C.</div><div style="text-align: center;">Control voltages for the HV and the Emission Current are always kept at 0VDC when the tube is OFF to prevent the tube from firing up due to a transient on the TTL "tube enable" signal during controller power-up and shut-down. These control voltages go up to the programmed levels just before the X-ray tube is turned ON and are dropped again to 0VDC shortly after the tube is turned OFF.</div><div style="text-align: center;">Another safety feature is a "parameter watchdog" - 2 seconds after the x-ray tube is on the beam is stable the controller will start actively monitoring for a difference between the set control voltages and the return monitor voltages - if a specified tolerance is exceeded, the controller will turn OFF the tube.</div><div style="text-align: left;"><br /></div><div style="text-align: left;">There is a relay with NO/NC contacts used for control of external equipment - X-Ray ON indicator, shutter, acquisition system, etc</div><div style="text-align: left;">The nRF52840 BLE will allow me to implement a Bluetooth connection to another host device (Smart phone for example) and control everything remotely. </div><div style="text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOgdyiudzY94bYx9WUDD7_bBU3mKPmLB09pSisX3Pb1rtwwNzZgfpdZgxcBTfEhn4PQ3DtPHB-gHmGXwpVe57AqUZfYGueHTzQEI8iemPopO-6cfcsBL8D63TVK5gY-f5YV9-WEOBxIhMfeKOzXla95M9UGV-xumaEaYMZLucEuM3q7494n7a_yyN6/s4493/X_Ray_Ctrl.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="3305" data-original-width="4493" height="235" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOgdyiudzY94bYx9WUDD7_bBU3mKPmLB09pSisX3Pb1rtwwNzZgfpdZgxcBTfEhn4PQ3DtPHB-gHmGXwpVe57AqUZfYGueHTzQEI8iemPopO-6cfcsBL8D63TVK5gY-f5YV9-WEOBxIhMfeKOzXla95M9UGV-xumaEaYMZLucEuM3q7494n7a_yyN6/s320/X_Ray_Ctrl.png" width="320" /></a></div><div style="text-align: center;"> This is the PCB design for the controller board.</div><div style="text-align: center;"> Critical modules are socketed and can be replaced easily. There is a terminal block and a DB-9 connector directly compatible with the Moxtek DB-9 on the Magnum series tubes and auxiliary 2-pin power connector used for tubes with higher than 4W power.</div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJtL33SygHentzF_SDHh9CYia-auzkM1NZwq44AvnvXHMW4eLfHULBKTzysy77A1Pe3lAeMrvXVqbZkRIXyE36Ijyq-VlKuKinBik8OIk4T5zA_ocrHZ4Kux0BbanyVhy47LcTD29d9CTXFAd3raEiZP9zDXm-OWDLWCCgNCu97Y-kJCfgOk8JZx4E/s2336/20230207_154307.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1550" data-original-width="2336" height="212" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJtL33SygHentzF_SDHh9CYia-auzkM1NZwq44AvnvXHMW4eLfHULBKTzysy77A1Pe3lAeMrvXVqbZkRIXyE36Ijyq-VlKuKinBik8OIk4T5zA_ocrHZ4Kux0BbanyVhy47LcTD29d9CTXFAd3raEiZP9zDXm-OWDLWCCgNCu97Y-kJCfgOk8JZx4E/s320/20230207_154307.jpg" width="320" /></a></div><div style="text-align: center;">For testing, I looped the DAC outputs used to Set the x-ray tube control parameters (the "S" display line on the display) to the ADC inputs for monitoring the tube's return (the bottom, "M" display line) and whatever is programmed as SET tracks perfectly on the MONITOR. The ADCs exhibit a small non-linearity up to about 2.4V (they run with 3.00V reference) - I plotted voltage set vs. voltage read and created a curve to correct it, which improved the accuracy quite a bit.</div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVbdApOrr4bpPE0ZF6xKwuKzIN9NfTE9q0cLQSf6sYIIyVGD__t99IyD2Dr5MBhgufF7MXi-5gqimvbdr8BHJG5351Wf_Qh7TxxvRrGXkFvfmer0XqiY62xy95bjms2QsTWLKqIT-IcDi4SiAsp1QR_kn4ImX1hBr8zA_tweypUXRXdAp3jhrUjZnU/s3024/20230207_154651.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1801" data-original-width="3024" height="191" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVbdApOrr4bpPE0ZF6xKwuKzIN9NfTE9q0cLQSf6sYIIyVGD__t99IyD2Dr5MBhgufF7MXi-5gqimvbdr8BHJG5351Wf_Qh7TxxvRrGXkFvfmer0XqiY62xy95bjms2QsTWLKqIT-IcDi4SiAsp1QR_kn4ImX1hBr8zA_tweypUXRXdAp3jhrUjZnU/s320/20230207_154651.jpg" width="320" /></a></div><br /><div style="text-align: center;">The internal ADCs of nRF52840 are configured for 12-bit resolution and using the built-in 3.0V (0.6V x5 Gain) voltage reference. The ADC noise is very typical for these chips - around ~3mV swing as seen on the plot. I might employ a ring-buffer and toss out the Min and Max values over a couple of seconds samples while averaging the rest in an attempt to get a more stable readout if I get bored - now the least significant digit exhibits some ADC noise from time to time - it is fairly stable due to the over-sampling conversation I am performing so no huge motivation to address this.</div><div style="text-align: center;"><br /></div></span>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-74326655671269461422022-10-18T13:58:00.044-04:002023-09-22T08:49:52.233-04:00Gamma Dog - Volume Control<p><span style="font-family: verdana;">One thing that was really bugging me with the Gamma Dog circuit was the original analog audio volume adjustment. </span></p><p><span style="font-family: verdana;">The MCU swings a digital output pin, driving the amplifier input between 0V and 3.3V. This output is connected directly to a linear (class D) 1W audio amplifier which employs a tiny trimmer-potentiometer for gain adjustment.</span></p><p><span style="font-family: verdana;">To adjust the audio level in the field, first I have to remove the screw plugging the adjustment access hole (everything on the front panel is dust-proof) and then use a small flathead screwdriver to turn the internal trimmer-pot - hardly a convenient thing to do every time I needed to change the volume.</span></p><p><span style="font-family: verdana;">I normally keep the audio level pretty loud (3/4 of full power) as it helps during windy conditions but when it is quiet and one is kneeling right in front of the instrument, digging a hole or trying to pinpoint specimens, the loud tone in your face can get a bit annoying. Sometimes there will be a couple of us using Gamma Dogs near each-other and becomes a pretty loud "concert" so quick volume control is a "plus". Not to mention the "dirty looks" I was getting at indoor mineral shows from ladies looking for "healing crystals" who didn't like the loud, variable pitch tone produced by the instrument. (I guess it wasn't "resonant to their aura" :-)</span></p><p><span style="font-family: verdana;">Solving the issue entirely on the software side without re-wiring the audio circuit and using push-pull between two PWM digital outputs was going to be pretty intrusive, and also I didn't want to use additional timers and CPU cycles just to control the volume, so I decided to implement a simple hardware solution - digital potentiometer control.</span></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghlqNzvTuOhs9xLSTuszzrfU9oXDD4lY50bXwXvYpmw7GMIjJs4Lm1qAvE5gaffTzraT_ong_C32mkLXGqwDVRGgzdpzn_YW48OH57tsh1uAYZddqlJf45ceIEBKbgePTcGEgp--Z9bxBco5q6oTKzsl0S8tFbEDOplRTekyEZFrwnE08Dpvi6gUUS/s1281/Screenshot_20221014_121245.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1281" data-original-width="1079" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghlqNzvTuOhs9xLSTuszzrfU9oXDD4lY50bXwXvYpmw7GMIjJs4Lm1qAvE5gaffTzraT_ong_C32mkLXGqwDVRGgzdpzn_YW48OH57tsh1uAYZddqlJf45ceIEBKbgePTcGEgp--Z9bxBco5q6oTKzsl0S8tFbEDOplRTekyEZFrwnE08Dpvi6gUUS/s320/Screenshot_20221014_121245.jpg" width="270" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">The two main candidates - Analog Devices AD5171 (6-bit resolution) and Analog Devices AD5243 (8-bit resolution) digital potentiometers - 10K resistance. Most digi-pots out there, unfortunately are using SPI interface for control.</span></div><div style="text-align: center;"><span style="font-family: verdana;">I, on the other hand, have a number of I2C devices in my Gamma Dog, so I wanted to stick with the microcontroller's I2C interface bus - this saves me the use of an additional digital output for Chip Select (CS) signal needed with the SPI interface.</span></div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhekGVg6DOczvKZtZkAuSz5ClC7gEozOOUq4klxo0vTpskyhNsWwWKMGQSr7bIiXrYo33O6fQOt13eEnNyogJmngT0VwkwGqTl1u94EW2F-Wu0yNrXE8FFx_rmarhBTBdtbH90oUZR-ApWcC4sStg24fAxEhXdI3YGy06FBvCDmT12bqwStVUMMcAnS/s1453/IMG-20220909-WA0002.jpeg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1453" data-original-width="1452" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhekGVg6DOczvKZtZkAuSz5ClC7gEozOOUq4klxo0vTpskyhNsWwWKMGQSr7bIiXrYo33O6fQOt13eEnNyogJmngT0VwkwGqTl1u94EW2F-Wu0yNrXE8FFx_rmarhBTBdtbH90oUZR-ApWcC4sStg24fAxEhXdI3YGy06FBvCDmT12bqwStVUMMcAnS/s320/IMG-20220909-WA0002.jpeg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">I mounted the chips on SMD-to-thru-hole adapter boards - Mouser #535-LCQT-MSOP10 from Aries Electronics for the MSOP-10 component (AD5243) and </span><span style="font-family: verdana;">Mouser #</span><span style="font-family: verdana;">485-121210 from Adafruit for the SOT-23-8 packaged (this one was a bit tricky to install as the MSOP-8 footprint on the board is larger and the leads were not overlapping</span><span style="font-family: verdana;"> the solder pads but rather just reaching the very edge of each pad)</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgD6CRVnIqNGWhlWLHRF-KhOjcVeJGw1YsSZoALUOFaRFt2ny08LbCVKM631nDcLLVQADCOCbKWKU2Yi-N1Y4F7l3omvnKorPPveuNceBMD4EWXvacBerJ4Q5ME4gem9-J9Wr4IsPmFbME9-PCqVGphjJMxnS87HOrR9DMzpoA8ZOyF-PwXUWdeu2gu/s1001/AD5243.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="868" data-original-width="1001" height="277" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgD6CRVnIqNGWhlWLHRF-KhOjcVeJGw1YsSZoALUOFaRFt2ny08LbCVKM631nDcLLVQADCOCbKWKU2Yi-N1Y4F7l3omvnKorPPveuNceBMD4EWXvacBerJ4Q5ME4gem9-J9Wr4IsPmFbME9-PCqVGphjJMxnS87HOrR9DMzpoA8ZOyF-PwXUWdeu2gu/s320/AD5243.jpg" width="320" /></a></div><span style="font-family: verdana;">At the end, I focused on the AD5243 chip - it is an 8-bit potentiometer - this means 256 positions, and the chip has two independent, addressable potentiometers / channels which gives me a lot more flexibility for future expansion. With the 10K version, each step is 39 Ohms.</span></div><div style="text-align: center;"><span style="font-family: verdana;">This IC is also using very low power - drawing about 6uA. </span></div><div style="text-align: center;"><span style="font-family: verdana;">Here is the Analog Devices <a href="https://www.analog.com/media/en/technical-documentation/data-sheets/ad5243_5248.pdf">Datasheet</a>.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiA-5QnL_PKPIEs0Sok9hF-SZAJGb-t8ZOm1B6fFB1c_Oi4sl_Wy4VEla8CfiJg6IUGfdc-reYzU25cEnKSmKvQQ7c9fek0xb50yu8N4NucAuxoZxNCtiGphubUmvgLGB31BCnetMhRE94xwA-XSp5B-0kfieWJPJmkfm9ZxB1pUwKUFeDEnUzijX5/s2795/IMG-20220916-WA0005.jpeg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2795" data-original-width="2160" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiA-5QnL_PKPIEs0Sok9hF-SZAJGb-t8ZOm1B6fFB1c_Oi4sl_Wy4VEla8CfiJg6IUGfdc-reYzU25cEnKSmKvQQ7c9fek0xb50yu8N4NucAuxoZxNCtiGphubUmvgLGB31BCnetMhRE94xwA-XSp5B-0kfieWJPJmkfm9ZxB1pUwKUFeDEnUzijX5/s320/IMG-20220916-WA0005.jpeg" width="247" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;"> Prototyping the solution. Added benefit was that I didn't have to write an Arduino library "from scratch" to control it -<a href="https://github.com/RobTillaart/AD524X"> Rob Tillaart already did this</a>. His library was written for AD5241 and AD5242 but works just as well with the AD5243 as it uses the same command set - only the I2C device address of the chip had to be changed to 0x2F. The I2C bus signals SDA and SCL require pull-up resistors.</div></span><div><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMt_iLiYBV8oAaMYT3PbEsDv4ARrCylzm_E3E1-jRhrOruDjl2DHZgkHnFJqZOvh0QjiwWnZzYH-Debsl-N9lw2qKVBLMXiMg85DuvAP5808iPlb9jYf6VpXtGi1pejlDxEdi0RvtxVDjLeSUfrRmi6aMMc1qZjxiyaWKjFoUWxijH1C-DN5FzTLyt/s1770/20221007_144445.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1467" data-original-width="1770" height="265" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMt_iLiYBV8oAaMYT3PbEsDv4ARrCylzm_E3E1-jRhrOruDjl2DHZgkHnFJqZOvh0QjiwWnZzYH-Debsl-N9lw2qKVBLMXiMg85DuvAP5808iPlb9jYf6VpXtGi1pejlDxEdi0RvtxVDjLeSUfrRmi6aMMc1qZjxiyaWKjFoUWxijH1C-DN5FzTLyt/s320/20221007_144445.jpg" width="320" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">The two SMD 10K pull-up resistors and a ceramic 100nF filter capacitor mounted on the converter PCB.</div></span><div><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvWlktYlum9-kurAPvLyaxobCCgSyZoDMSQhhIS2KrcQHl7t-VRQrCtzU4XEltfuXe3vXter0NSf7rcIuz1vc2EnMF_ikKg3paepdFgaYcoMqzKY6dMRuLq_6Ht-wtHTLyu135ZeCQUHXq8OBV0Z2hHOnXUpJ_fQtwuYc0T5xJJMLpO31WrUS_iIt6/s1842/20221008_085256.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1818" data-original-width="1842" height="316" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvWlktYlum9-kurAPvLyaxobCCgSyZoDMSQhhIS2KrcQHl7t-VRQrCtzU4XEltfuXe3vXter0NSf7rcIuz1vc2EnMF_ikKg3paepdFgaYcoMqzKY6dMRuLq_6Ht-wtHTLyu135ZeCQUHXq8OBV0Z2hHOnXUpJ_fQtwuYc0T5xJJMLpO31WrUS_iIt6/s320/20221008_085256.jpg" width="320" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">On the board I connected Ch.1 pot's B1 pin to ground and added also 10uF / 16V tantalum capacitor across the power supply rail to minimize any transient disturbance and low frequency ripple.</div></span><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWmFTwGz66p-Yr4q0MkEJdzD20Lre6pwUnINB_7mmJbkOPUQ0xrhwhZ5xQCWntBcOHEqobI6crslC3GFwHSIh3huOVWV1ht2-QRw2oFN6JHFH5n9iCSeWxYOYUAxacqh120QprdBVsQbdl2V8yur-Vj8iJrulwfQR6vDfZSYp_Jb9EeQ9opEhMX7_7/s3240/20221007_211904.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1657" data-original-width="3240" height="164" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWmFTwGz66p-Yr4q0MkEJdzD20Lre6pwUnINB_7mmJbkOPUQ0xrhwhZ5xQCWntBcOHEqobI6crslC3GFwHSIh3huOVWV1ht2-QRw2oFN6JHFH5n9iCSeWxYOYUAxacqh120QprdBVsQbdl2V8yur-Vj8iJrulwfQR6vDfZSYp_Jb9EeQ9opEhMX7_7/s320/20221007_211904.jpg" width="320" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">I designed the digital potentiometer volume control as an add-on board which is inserted inline between the speaker / amp board and the main board's speaker connector. This connector provides signal and power to both, the digi-pot and the audio amplifier. The I2C bus is connected to the I2C bus on the Latching Relay FeatherWing shield with a separate line. </div><div style="text-align: center;">JST connectors allow for an easy, no-soldering install in the units.</div></span><div><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfhZLxeWZ-9aUbskIENnG-MO9SBe-0jgxOFVcCdRHo2JoHGHvdvJO8IIltEzUD0qMIsJJ900Lgx87lVTSE3i35iD1k95GnkwSxwj0IEQDS-Wz4x3FG-5zlVEMWErGoKlTxxQq3udR7Yi9OiFMDIQ3e1vORqPXsax5GHuoTRRZ8sowTFTD31YqviAGX/s2621/20221007_214034.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1868" data-original-width="2621" height="228" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfhZLxeWZ-9aUbskIENnG-MO9SBe-0jgxOFVcCdRHo2JoHGHvdvJO8IIltEzUD0qMIsJJ900Lgx87lVTSE3i35iD1k95GnkwSxwj0IEQDS-Wz4x3FG-5zlVEMWErGoKlTxxQq3udR7Yi9OiFMDIQ3e1vORqPXsax5GHuoTRRZ8sowTFTD31YqviAGX/s320/20221007_214034.jpg" width="320" /></span></a></div><div><div style="text-align: center;"><span style="font-family: verdana; text-align: left;">The complete add-on volume control module. The board was placed inside a heat-shrink tube for electrical and mechanical protection. On the left side are the output to the amplifier board pigtail and the input connector. On the right side is the I2C bus connector. The 3-pin input/output JST connectors deliver power to the board and to the audio amplifier.</span></div><div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEin5QVV7-jP-giBBD7nyyixecBJtrqJi4uacAPUZJiIxuOc7PDHPYLF82jJEM1004QmJ7ylD2G67mUB3e548PHJx_5prEa3C4ADVoS8Gtr83vV0q1v9E52GJwhxo3WliCOD37NyPa0dQEgmMnsdM4em94oN6iMUZvtaB7c5lCyaMINosq-Uliqisj3g/s3475/20221007_220259.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1868" data-original-width="3475" height="172" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEin5QVV7-jP-giBBD7nyyixecBJtrqJi4uacAPUZJiIxuOc7PDHPYLF82jJEM1004QmJ7ylD2G67mUB3e548PHJx_5prEa3C4ADVoS8Gtr83vV0q1v9E52GJwhxo3WliCOD37NyPa0dQEgmMnsdM4em94oN6iMUZvtaB7c5lCyaMINosq-Uliqisj3g/s320/20221007_220259.jpg" width="320" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">The add-on board installed in the Gamma Dog. Visible on the right is the I2C bus line going to the FeatherWing Relay pins which are basically a signal feed-through to the MCU board.</div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiviR-cAuLuWHxjA296S2ptGbOjv4i47T0O1ipqUaKqfzuI1_16Fxlay0oIq54OhBUOw86V8YOB7hi8rM7A91ASLfNWYPXmVz4KeQeH9Y4AmT6894-ACfxKLwIEkoKwqAxzmFDHI-WqVDHpWty9pXVevckLC8kzNu-JWPkbhC10R40Fz5ceK5IzEMXu/s3322/20221008_131050.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3322" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiviR-cAuLuWHxjA296S2ptGbOjv4i47T0O1ipqUaKqfzuI1_16Fxlay0oIq54OhBUOw86V8YOB7hi8rM7A91ASLfNWYPXmVz4KeQeH9Y4AmT6894-ACfxKLwIEkoKwqAxzmFDHI-WqVDHpWty9pXVevckLC8kzNu-JWPkbhC10R40Fz5ceK5IzEMXu/s320/20221008_131050.jpg" width="320" /></a></div><div style="text-align: center;"> Adding these volume control modules to my fleet of Gamma Dogs was effortless and looks as elegant as an inline add-on board can be. I made 3 such modules.</div></span><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHI7UCwbcvq53D8KF3ZVL487jSxSjbnkz50zu2ta2U2Qe-pa20oqeQBIWbgGB068FgmaYsxFl2b9etUFswA-3V1-okwr0HIZ_D04_eebWEaKlVIVKg6WsAzBo5sQ6YlqrM3miZT6bEyz3WDzrtFr2XkHTANfcksD3eKzY22VYPCfx_IScNg98yqSaP/s2542/20221018_131105.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1658" data-original-width="2542" height="209" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHI7UCwbcvq53D8KF3ZVL487jSxSjbnkz50zu2ta2U2Qe-pa20oqeQBIWbgGB068FgmaYsxFl2b9etUFswA-3V1-okwr0HIZ_D04_eebWEaKlVIVKg6WsAzBo5sQ6YlqrM3miZT6bEyz3WDzrtFr2XkHTANfcksD3eKzY22VYPCfx_IScNg98yqSaP/s320/20221018_131105.jpg" width="320" /></a></div><span style="font-family: verdana;">Crude schematics I sketched while developing the volume control. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The digital potentiometer acts as an adjustable voltage divider for the output signal. The "wiper" is connected to the input of the audio amplifier. </span></div><div style="text-align: center;"><span style="font-family: verdana;">Ch. 2 potentiometer is currently unused. <br /><br /></span></div><div><span style="font-family: verdana;"><br /></span></div><div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/11PlOa38Ogs" width="320" youtube-src-id="11PlOa38Ogs"></iframe></div></div><div style="text-align: center;"><span style="font-family: verdana;">Writing the firmware support, I implemented two ways to adjust the Audio Volume using the Gamma Dog's user-interface. </span></div><div style="text-align: center;"><span style="font-family: verdana;">A menu item in the Configuration Menu can select one of 6 volume levels - from a very soft sound suitable for a quiet room to maximum loudness for windy conditions. 6 Volume Levels seems to cover the entire range nicely and I see no need for the "classic" 0 to 10 volume range. This adjustment sets the default volume level of the instrument, and it is persistent (saved in the EEPROM and then loaded on startup).</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;">If the user needs only a quick, temporary adjustment - double-click on the BLUE/UP button will switch the instrument to Constantly Open (Latched) Squelch Mode and the current volume level will be displayed right next to "#" symbol. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The Constantly Open squelch Mode will produce naturally a continuous tone that can be used as audio level feedback. The user then can press the GREEN/DOWN button to cycle thru the available 6 volume levels. Once a selection is made, same BLUE/UP Double-Click action will turn off the Constantly Open Squelch Mode and return the instrument to normal squelched mode with the new audio volume level. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The volume adjustment in this case is not persistent, and the instrument will revert to the default volume level set thru the Config Menu System on the next restart.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;">The add-on volume control board bumped up the firmware code version to 4.0. The board is backwards compatible with older firmware versions - if the AD5243 code is missing, the pot will automatically set the "wiper" to the "middle position" (127) during power-on (which actually equates to MAX volume when 10K chip is used). The useful adjustment range with a 10K potentiometer chip is approx. 0 to ~64 steps (1/4 of the 8-bit range or 0 to 2.5K) in my circuit - anything above 70 and all the way to 255 is really MAX volume.</span></div><div style="text-align: left;"><span style="font-family: verdana;">Ideally, I should have probably picked a lower resistance value (2.5K) but I don't need such fine adjustments with only 6 volume steps to spread across an 8-bit range and 10K is useful for some other ideas I have for the unused pot on the chip.</span></div></div></div></div><div style="text-align: left;"><br /></div><div style="text-align: left;"><span style="font-family: verdana;">Another future possibility is to use a digi-pot control for the HV bias power supply for the detector - currently this is done with another trimmer-pot on the HV board and requires the removal of 3 screws to access it.</span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;">I am quite happy with the volume control implementation, and it works just as expected!</span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;">Firmware version 4.4 marks the end of the current development efforts for my branch of Gamma Dog - the instrument at this stage is mature and polished, performance is excellent, firmware is clear of bugs.</span></div><div style="text-align: left;"><span style="font-family: verdana;">The last added feature in ver. 4.4 is <b>"Gesture Control" for the Squelch Auto-Set.</b> When this option is enabled in the menu system, the GD monitors its orientation and if it is inverted (upside-down, </span><span style="font-family: verdana;">detector pointing to the sky</span><span style="font-family: verdana;">) for more than 4 seconds it will activate Squelch Auto-Set. This allows for one-handed operation in the field - instead of pressing and holding the BLUE button to set the current squelch level, the user just changes the orientation of the instrument.</span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;">Hardware version 4 is already developed as a new PCB layout and adds small layout improvements, the incorporation of the digital potentiometer and a couple of new features - "Charge Complete" LED indicator as part of the GREEN button and a circuit for measuring and displaying the HV Bias for the PMT (up to 1.25kV). The built-in HV voltmeter can be used for diagnostics and voltage adjustments in the field, for example when switching to a different detector. </span></div><div style="text-align: left;"><span style="font-family: verdana;">If I decide to fabricate more PCBs, all these will be ver. 4 and firmware will go to ver. 4.5, adding support for the new features.</span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;">In my free time I'll work on documentation, schematics and source code, pending a decision whether to open it and make the project public.</span></div><div style="text-align: left;"><span style="font-family: verdana;">Unfortunately, given the niche application of this instrument, the general interest has been rather sparse, but I would love to hear feedback.</span></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com2tag:blogger.com,1999:blog-5557902467288736826.post-31490828743911807562022-05-21T13:11:00.013-04:002023-04-18T10:15:43.752-04:00Gamma Dog - Performance<p><span style="font-family: verdana;"> So how does the Gamma Dog perform? </span></p><p><span style="font-family: verdana;"><b>The short answer is - fantastic!</b> </span></p><p><span style="font-family: verdana;">I am really happy with the performance. Charles and I have been testing our instruments inside and out and they work great - sensitivity is excellent so as the ease of use. The operation is a complete joy and a fun user experience just to go out in the field and hunt for radioactive minerals with the Gamma Dog. We seem to have nailed all of our design goals and there isn't anything I can think of to improve the instrument further.</span></p><p style="text-align: center;"><span style="font-family: verdana;">Here is just a small fraction of the specimens I have collected with my Gamma Dog.</span></p><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjpAaAUg4WTGpMRnadWpsUqe8esAreXTtN_WKpAiMkfFncV2F_cSKDKSKXXUVCm5Q8kviBJ75rZt36hEPTMvvzFnyRV4xtsVIA8GDeErY6BYBjTzT41AA3lbR-CjcqV99Cv45oUQNEAv26QuQp8hHbd6mSyzeyWz1LSG7AO35xlWp5VB3oiOWMBhB9P/s2492/20220302_135937.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2492" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjpAaAUg4WTGpMRnadWpsUqe8esAreXTtN_WKpAiMkfFncV2F_cSKDKSKXXUVCm5Q8kviBJ75rZt36hEPTMvvzFnyRV4xtsVIA8GDeErY6BYBjTzT41AA3lbR-CjcqV99Cv45oUQNEAv26QuQp8hHbd6mSyzeyWz1LSG7AO35xlWp5VB3oiOWMBhB9P/s320/20220302_135937.jpg" width="240" /></a></span></div><div style="text-align: center;"><span style="font-family: verdana;">This little Euxenite crystal (on top of a US Dime for scale) I found under 2-3 inches of silt and sand in a wash near the pegmatite at White Signal, NM</span></div><p></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDhK1c-36J3Kb3cvX_piBQALp7Gi20xQJg-qR_HrLMoctZEvJogx5wPa08DSFgYCu8POuYfusj-xw0vLyYlaYyF4l-lqYS_VEgKBlVuvbjVGn67tWZPb42ug0hninQz0jShY-fAc2vpFVuLJifDsl8ieP7gsp5WR75GbCwkdIxv9ZcXryz6dkEvwp-/s2233/20220303_131239.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2233" height="268" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDhK1c-36J3Kb3cvX_piBQALp7Gi20xQJg-qR_HrLMoctZEvJogx5wPa08DSFgYCu8POuYfusj-xw0vLyYlaYyF4l-lqYS_VEgKBlVuvbjVGn67tWZPb42ug0hninQz0jShY-fAc2vpFVuLJifDsl8ieP7gsp5WR75GbCwkdIxv9ZcXryz6dkEvwp-/s320/20220303_131239.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">This is the haul of Euxenite crystals over a couple of days Charles and I found in a single "honey" pot at White Signal, NM. </span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihPNhHRS_h2KMu1ctIaLB93M0qcdp9sTWLr1G38ps1I2R8XaK7csnioV1dEOdfI_-itf2mT_BTX3pELKorXbUQ3yNL3Kd7MNiNVaX-2vGTb6qZHlcdYluqbsm-tVLkauxvDO64f4BAfXbs3xILbScBdPEBobowYdKkDl2NR7kOJD8znr4QRedAXRBp/s2240/20220207_163611.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2240" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihPNhHRS_h2KMu1ctIaLB93M0qcdp9sTWLr1G38ps1I2R8XaK7csnioV1dEOdfI_-itf2mT_BTX3pELKorXbUQ3yNL3Kd7MNiNVaX-2vGTb6qZHlcdYluqbsm-tVLkauxvDO64f4BAfXbs3xILbScBdPEBobowYdKkDl2NR7kOJD8znr4QRedAXRBp/s320/20220207_163611.jpg" width="267" /></a></div><span style="font-family: verdana;">I found this gigantic Euxenite crystal, one of the biggest I've seen - it wasn't difficult to find though, with an with activity of almost 8000 CPS, the Gamma Dog was howling. Charles found an unusually high-activity area and started digging a hole but then he attributed the activity to the "mass-effect". I decided to give the hole a second chance and it produced this fantastic crystal.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsVgI5XzU4uycME7kXerTbHT_LyJG10ZEJVELoHrInZnQBzp5OsC7a1AGVyCWJzX22gMWRvdI3rmXto4dfnabck9vzCn33D3q1t7tUxgkx0kFJA4EDnHt2gQK99Z2zyWnDnutj6h_NowjV1P9DhIzs-ipdOzrM9-Q9n84BFbu9xYU6rHpzhNwhxAOs/s2097/20220207_163841.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2097" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsVgI5XzU4uycME7kXerTbHT_LyJG10ZEJVELoHrInZnQBzp5OsC7a1AGVyCWJzX22gMWRvdI3rmXto4dfnabck9vzCn33D3q1t7tUxgkx0kFJA4EDnHt2gQK99Z2zyWnDnutj6h_NowjV1P9DhIzs-ipdOzrM9-Q9n84BFbu9xYU6rHpzhNwhxAOs/s320/20220207_163841.jpg" width="285" /></a></div><span style="font-family: verdana;">Another interesting Euxenite - the "corner" void was caused by a weathered quartz crystal which crumbled and disintegrated when I pulled it out. I guess the radiation onslaught over millions of years was too much for it.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjx78Pir8K_nAO-q127C1YZUaHydIw0HgJQhnJFzqBsTUVZxqbGZbf_KaF0Ovy0E1xHVexlQOD9cM2Yk7qCSYkmUpFSeT_hg_srC8Lg9HZFyaO_mYJWdAyvDyhd6GWoL7w52PFO_tDpMpfsG3mJM-ymjIGak_hDDC2W5crtwc4605qwMlIkQsp8zhBv/s3840/Euxenite-fan.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1883" data-original-width="3840" height="157" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjx78Pir8K_nAO-q127C1YZUaHydIw0HgJQhnJFzqBsTUVZxqbGZbf_KaF0Ovy0E1xHVexlQOD9cM2Yk7qCSYkmUpFSeT_hg_srC8Lg9HZFyaO_mYJWdAyvDyhd6GWoL7w52PFO_tDpMpfsG3mJM-ymjIGak_hDDC2W5crtwc4605qwMlIkQsp8zhBv/s320/Euxenite-fan.png" width="320" /></a></div><span style="font-family: verdana;">A very interesting crystal habit of Euxenite (White Signal, NM) - I found the one on the left with my Gamma Dog and Charles found the one on the right. Both crystal are in the collection of Charles now. </span></div><div style="text-align: center;"><span style="font-family: verdana;">Picture by Charles David Young.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJNsQu4JeR6xETtfuEUaVPsZ58lAyjuO2L5qfepcLj1tfNETgXRg1axpe3bmomFtdMx8TkoqvTZmBbgF4s--XU_jTZWm-HYfKgbRSUWAO6ix6GW3oMjQA9-2X1MyC4mG8IJUNJYOm2VMofEZY9WEM-g_GYHL7xBOGeFA021sOayXPre_xuLOuVmGZF/s2473/20220310_133735.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1854" data-original-width="2473" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJNsQu4JeR6xETtfuEUaVPsZ58lAyjuO2L5qfepcLj1tfNETgXRg1axpe3bmomFtdMx8TkoqvTZmBbgF4s--XU_jTZWm-HYfKgbRSUWAO6ix6GW3oMjQA9-2X1MyC4mG8IJUNJYOm2VMofEZY9WEM-g_GYHL7xBOGeFA021sOayXPre_xuLOuVmGZF/s320/20220310_133735.jpg" width="320" /></a></div><span style="font-family: verdana;">Allanite-(Ce) crystals I found over a couple of hourd with my GD at the Kingsman Feldspar Mine, Kingsman, AZ</span><br /><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqHuTx-_oHeitLLHsOJ-_YVd_sHvrLTdpURRkFulIRdlyN4G9kCz2YF7nxbeaPIPvXzfGR6q4idiNwK2nxl23__cEggo551TrCYWLKHL7TNzrKHO-H1IC0auBm35839IEJcgUL0RmnBwflf_Rav4-SepToAaSwUC8Jq-ioti9RroHR66cyjVsw6D9n/s2005/20220310_133744.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2005" height="298" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqHuTx-_oHeitLLHsOJ-_YVd_sHvrLTdpURRkFulIRdlyN4G9kCz2YF7nxbeaPIPvXzfGR6q4idiNwK2nxl23__cEggo551TrCYWLKHL7TNzrKHO-H1IC0auBm35839IEJcgUL0RmnBwflf_Rav4-SepToAaSwUC8Jq-ioti9RroHR66cyjVsw6D9n/s320/20220310_133744.jpg" width="320" /></a></div><span style="font-family: verdana;">Closeup of one of the Allanite-(Ce) specimens from Kingsman, AZ</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjv4pxaftPFgYacTX6MRJ-jNcjlxVP0aHI2iW3MqvB2cjv15HUOyqu2PagboNmAwNJCTT_DPuSioT5gtDaR9QQNzpQZHmjUZL4zesB2v9Oqd5STyh2JI5TWgtk7T2Sjf5Ui8k6MXIipNhy-gjm2J3iy6lxiH8XnnL4MdQxMU6tfwzgLQHpX2A_vDdWU/s2549/20220507_104951.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1727" data-original-width="2549" height="217" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjv4pxaftPFgYacTX6MRJ-jNcjlxVP0aHI2iW3MqvB2cjv15HUOyqu2PagboNmAwNJCTT_DPuSioT5gtDaR9QQNzpQZHmjUZL4zesB2v9Oqd5STyh2JI5TWgtk7T2Sjf5Ui8k6MXIipNhy-gjm2J3iy6lxiH8XnnL4MdQxMU6tfwzgLQHpX2A_vDdWU/s320/20220507_104951.jpg" width="320" /></a></div><span style="font-family: verdana;">Quartz with Copper ore and black Uraninite inclusions from the Green Monster Mine south of Las Vegas, NV.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPXfAj6_wpKoQKb5NDIlkrEwoGwQOiQnJnt3DAv-RPOA0YDOaHKcUWuABwq4HZkuGfIzysUNt1fgevpeZ2YHGdsDBXCxtENjIIGK6hSOYn50m5cnQFP4mM5-m3XROwlsozXfwvYh2JiWVLb-VDqej3sdfm-BbH-JKopqm98ePcDH6Ae8-u4YmYVOJx/s2361/20220601_134300.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2361" height="253" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPXfAj6_wpKoQKb5NDIlkrEwoGwQOiQnJnt3DAv-RPOA0YDOaHKcUWuABwq4HZkuGfIzysUNt1fgevpeZ2YHGdsDBXCxtENjIIGK6hSOYn50m5cnQFP4mM5-m3XROwlsozXfwvYh2JiWVLb-VDqej3sdfm-BbH-JKopqm98ePcDH6Ae8-u4YmYVOJx/s320/20220601_134300.jpg" width="320" /></a></div></div><div style="text-align: center;"><span style="font-family: verdana;">Uraninite (the two on the left) crusted with secondary minerals (Gummite) and Zircon? (on the right) from the Biermann Quarry, Bethel, Fairfield County, Connecticut</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUH0ThAVaCobIyoQzzb0dOe6SU-5ux6W33LYHqDFw2dOqlU2fmx2g5XUFqGTZ3H_OS3cbBQHYnHUvbpaKzPKWbViluWf4rp5HfOgwQUYZm890IKAudiSmz_SrgHvglgQ6UQvlJfEHgU2izKZs4SoCqhUxiAeS5zE0V8XKoMxXnvFXxUU5urir7kR03/s2070/20220918_121812.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="913" data-original-width="2070" height="141" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUH0ThAVaCobIyoQzzb0dOe6SU-5ux6W33LYHqDFw2dOqlU2fmx2g5XUFqGTZ3H_OS3cbBQHYnHUvbpaKzPKWbViluWf4rp5HfOgwQUYZm890IKAudiSmz_SrgHvglgQ6UQvlJfEHgU2izKZs4SoCqhUxiAeS5zE0V8XKoMxXnvFXxUU5urir7kR03/s320/20220918_121812.jpg" width="320" /></a></div><span style="font-family: verdana;">Collection of Samarskite-(Y) crystals, I managed to find within a few hours at </span><span style="text-align: left;"><span style="font-family: verdana;">Dollar Bill claims, Little Rincon Mountains, Pima County, Arizona</span></span><span style="font-family: verdana;"> </span></div><div style="text-align: center;"><span style="font-family: verdana;"><span><br /></span></span></div><div style="text-align: center;"><span style="font-family: verdana;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3wqfZlEBbyBCtQBBw1fnYluqJpNVtpto7Qdvni_cMqP62SMgRzIeyvb5pQOvSabcwqVtzbvSuulrH5x7RSC6tyehSYNGuwxUuHw2Z6Re34YzYTozXj5hoUst68UiK_buMiK0u4SQPOrV2Shs6NuEdEbQ9wXteb2bXvh6nEyMQZ2y6bsE6nXszpQqs/s3300/euxenite_dollar_bill.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1878" data-original-width="3300" height="182" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3wqfZlEBbyBCtQBBw1fnYluqJpNVtpto7Qdvni_cMqP62SMgRzIeyvb5pQOvSabcwqVtzbvSuulrH5x7RSC6tyehSYNGuwxUuHw2Z6Re34YzYTozXj5hoUst68UiK_buMiK0u4SQPOrV2Shs6NuEdEbQ9wXteb2bXvh6nEyMQZ2y6bsE6nXszpQqs/s320/euxenite_dollar_bill.png" width="320" /></a></div>I found this nice doubly terminated and fairly large for the locality (2.5cm x 1.5cm x 1cm) Euxenite-(Y) crystal at the Dollar Bill claims, Little Rincon Mountains, Pima County, Arizona</span></div><div style="text-align: center;"><span style="font-family: verdana;">(picture credit: Charles David Young)</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrzjvzIevP4c6uuSKRTCj-5OATjm5BWLkaHE-yRZo2EsuG_tp97Omk6NGL22o4AyJ8GCNs8M51IBNm3S2UOAZHiZgA0CCvY4ifaEJvxOGrBdYRGa1af6m5uyi7lDRVB2yrIv9SfaolM8g0q537fTMJ0PRrqvx70XWKzgH2XFosV8acgrB66TjWcIin/s3300/euxenite_dollar_bill_xrf.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1878" data-original-width="3300" height="182" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrzjvzIevP4c6uuSKRTCj-5OATjm5BWLkaHE-yRZo2EsuG_tp97Omk6NGL22o4AyJ8GCNs8M51IBNm3S2UOAZHiZgA0CCvY4ifaEJvxOGrBdYRGa1af6m5uyi7lDRVB2yrIv9SfaolM8g0q537fTMJ0PRrqvx70XWKzgH2XFosV8acgrB66TjWcIin/s320/euxenite_dollar_bill_xrf.png" width="320" /></a></div><span style="font-family: verdana;">Charles Young did a quick XRF of the crystal above, showing that the Uranium peak is smaller than the Yttrium peak - characteristic signature of Euxenite-(Y).</span><br /><span style="font-family: verdana;"><span><br /></span></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/RmA7IzSsGzo" width="320" youtube-src-id="RmA7IzSsGzo"></iframe></div><span style="font-family: verdana;">Prospecting at the Dollar Bill Claim, Mescal, Arizona.</span></div><div style="text-align: center;"><span style="font-family: verdana;">Another great video by Charles David Young.<br /></span><span style="font-family: verdana;">The Gamma Dog makes it all possible - I can't imagine ever going back to any other detector for this application.</span></div><div style="text-align: center;"><br /></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/q2fT-LdVYN8" width="320" youtube-src-id="q2fT-LdVYN8"></iframe></div><span style="font-family: verdana;">A quick overview of the Gamma Dog.</span><br /><span style="font-family: verdana;"><br /></span></div><p></p>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-70126390449595794442022-04-13T19:37:00.020-04:002023-04-18T10:15:58.383-04:00 Gamma Dog EXP - External Probe<p><span style="font-family: verdana;">The idea behind Gamma Dog EXP is to have a self-contained electronics module which I can connect to various external probes. This allows a certain level of flexibility - detectors using smaller crystal can be attached to a wand and used in the "Metal Detector" style setup, sweeping larger areas much faster or an alpha scintillator can be connected to check for contamination. I also use this setup very effectively during mineral shows (sans the wand) and I can quickly sweep across the tables with specimens.</span></p><p><span style="font-family: verdana;">The large internal detector unit is just too big and heavy to be mounted on a pole and the range of scanning around a person with it is limited to an arm's reach.</span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWWZYvYnq39pk9PMih4-RhokcmiV8mKpDH7Xr9u7bTLKH8BfKHk5jSE1vid0sp90kv71-Uo6Bpa89vDnVMz8vGmvhr9ZA4DPtKyiEYbBIwyeoT4UsE8iXDd8wJEQzvXQpsWspF7TvMBX4MKMxd3mAcEvl7RQXYHG6Qv1S64rphXzYhvughCrTn-09_/s2780/20220503_101333.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2780" height="215" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWWZYvYnq39pk9PMih4-RhokcmiV8mKpDH7Xr9u7bTLKH8BfKHk5jSE1vid0sp90kv71-Uo6Bpa89vDnVMz8vGmvhr9ZA4DPtKyiEYbBIwyeoT4UsE8iXDd8wJEQzvXQpsWspF7TvMBX4MKMxd3mAcEvl7RQXYHG6Qv1S64rphXzYhvughCrTn-09_/s320/20220503_101333.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;"> This is the entire setup mounted on a "Metal Detector" style armrest and pole using a low-profile detector using 40x80 mm NaI(Tl) crystal</span></div><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWi7-TXmS7dL23WptlQIS4Q7RGjIdDyzSgG425BcVySaZUcJYk_4CiowHM6zOIAzCyfGOSCFdx9Xq7XeUjMHu8XEEYF2CRdt0HTk_3Y0z5_C9zNNyn3_mpRyX8j5Gm3KnnnF1PWrsyLmuRQ1LK8e1BmjPKi933ZbxVYNVWmJbCJk3vk8zlTUaC5Ysm/s1837/20220215_094121%20-%20Copy.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1837" data-original-width="1812" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWi7-TXmS7dL23WptlQIS4Q7RGjIdDyzSgG425BcVySaZUcJYk_4CiowHM6zOIAzCyfGOSCFdx9Xq7XeUjMHu8XEEYF2CRdt0HTk_3Y0z5_C9zNNyn3_mpRyX8j5Gm3KnnnF1PWrsyLmuRQ1LK8e1BmjPKi933ZbxVYNVWmJbCJk3vk8zlTUaC5Ysm/s320/20220215_094121%20-%20Copy.jpg" width="316" /></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">The self-contained electronics module came out pretty compact. It can be placed in a backpack or even hanging from a belt.</span></div></span><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCrUyzrR4PCnJsQnz2wBbyC-3XSVKVhw4ROIaqzwEAvpXAPGHDQqUtNAp6RAM6rKTZmYGxOpt5xWopHOomv3qhy9mahyUHu21MnlwD0vq3LdaTm64KDmjLBqB59NN0xb1e0Yko1IExpq9bd3_WdwO85WdwaogQCToQGaaZyIF9qqR_7fqP-J222m7K/s2491/20220215_093505.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1867" data-original-width="2491" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCrUyzrR4PCnJsQnz2wBbyC-3XSVKVhw4ROIaqzwEAvpXAPGHDQqUtNAp6RAM6rKTZmYGxOpt5xWopHOomv3qhy9mahyUHu21MnlwD0vq3LdaTm64KDmjLBqB59NN0xb1e0Yko1IExpq9bd3_WdwO85WdwaogQCToQGaaZyIF9qqR_7fqP-J222m7K/s320/20220215_093505.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">Over-the-shoulder strap is another, very convenient way to carry the unit.</span></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIWEk8vBU7CZx0CBQdJanP0rSYc1apACe0Lb2VLKVoWt61kM7jqb9QuBmspZdzXdUm5tvCZYnxLV_UCfOXJkP3T_P5Nx3ndRt8_Kn0wAYaOaBx1tHMokJwIcK_uP2t1tvOfgXSzHD_m8XkwhmOirXkMbYDYY_aj0DYOW495Ygq6t0iBgfJz3FmTIPL/s3339/20220215_094016.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3339" height="179" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIWEk8vBU7CZx0CBQdJanP0rSYc1apACe0Lb2VLKVoWt61kM7jqb9QuBmspZdzXdUm5tvCZYnxLV_UCfOXJkP3T_P5Nx3ndRt8_Kn0wAYaOaBx1tHMokJwIcK_uP2t1tvOfgXSzHD_m8XkwhmOirXkMbYDYY_aj0DYOW495Ygq6t0iBgfJz3FmTIPL/s320/20220215_094016.jpg" width="320" /></a></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsE6X2TO228unjj8Y1MjpmKZ8gPfLBTOnpY9-Wubmtc-8T-DtlPEHEmnOXCKwO2rPHs77XBeTbiVIc-9vjREGGR4KwpT94Sgv96ssNSZU6PDYuaz6FZS_5PmvH_VwEL-WlTBhRkeibLbEd42gEMAh7lMnFf9YgthXuSFu7LyfwI_U6NmZTbPq6FgEr/s4000/20220215_093936.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="4000" height="149" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsE6X2TO228unjj8Y1MjpmKZ8gPfLBTOnpY9-Wubmtc-8T-DtlPEHEmnOXCKwO2rPHs77XBeTbiVIc-9vjREGGR4KwpT94Sgv96ssNSZU6PDYuaz6FZS_5PmvH_VwEL-WlTBhRkeibLbEd42gEMAh7lMnFf9YgthXuSFu7LyfwI_U6NmZTbPq6FgEr/s320/20220215_093936.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">`BNC connector for attaching the scintillating probe. Bias voltage is set internally (up to 1000V) and VD impedance of the PMT must be above 60MOhms.</div><div style="text-align: center;"><br /></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfPR1B9Eps_-YAGBKDsjSlswjZ6_HCnhvRVMQRF7HRukJ5Ask3Q-yGvncmEXECz-1yMKaqSHAAsUTy-c5ImatRQWICPwvgLC-Co2IxLmWcw0kN4Vv_IDs6rW81qEJun-7bkxNb-qPG59fZI7NWnrMzDwumLpto6o8TuziRi16ztU78Bewz6OoZ64K9/s2228/20220409_125244.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1849" data-original-width="2228" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfPR1B9Eps_-YAGBKDsjSlswjZ6_HCnhvRVMQRF7HRukJ5Ask3Q-yGvncmEXECz-1yMKaqSHAAsUTy-c5ImatRQWICPwvgLC-Co2IxLmWcw0kN4Vv_IDs6rW81qEJun-7bkxNb-qPG59fZI7NWnrMzDwumLpto6o8TuziRi16ztU78Bewz6OoZ64K9/s320/20220409_125244.jpg" width="320" /></a></div>Gamma Dog - skinned :-) the electronics only. </div><div style="text-align: center;">The black cylinder is a 63x63 NaI(Tl) scintillator connected with a short coaxial cable to the Gamma Dog's main board. The 6600mAh LiPo battery is on the right-hand side, speaker + amp, the 3 buttons and the display module can be seen as well.</div><div style="text-align: center;"><br /></div></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLo_N7olAC2J_RGvqDCFRkHjRchGu_0vTC8wJVGS58Do7RN-9lEDukQzQTl8Hw6ra58WdBWQEjspxe-U6x833R069D2Zyh88DtqgNEBvfcNkdrg8acj9TIsami9C36OrlHtJhORmtKn1xB_u_hNRLsvwZANFluYj7Onla0i090waWNOAVvXAxWkYS0/s2772/20220311_133010.jpg" style="margin-left: 1em; margin-right: 1em;"></a><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLo_N7olAC2J_RGvqDCFRkHjRchGu_0vTC8wJVGS58Do7RN-9lEDukQzQTl8Hw6ra58WdBWQEjspxe-U6x833R069D2Zyh88DtqgNEBvfcNkdrg8acj9TIsami9C36OrlHtJhORmtKn1xB_u_hNRLsvwZANFluYj7Onla0i090waWNOAVvXAxWkYS0/s2772/20220311_133010.jpg" style="margin-left: 1em; margin-right: 1em;"></a><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjt4PDXM8pwS0Xz0gojcDlSvtLb7lKHIS9eue7B7RgG27gHZAmUlJaFKczq_ZDg_hFnjdB26nvIRRrPgRd0-j9eAMLnqkMhKy1XxwvyMvNsIvgoKf_3rOOZWs1vspPvenKPUE7voyIL1S3s3PWkGNeKPKGJsxe7DxKiCOaXLHDinG35mR6tMEEW8RR-/s1869/20220411_101213.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1869" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjt4PDXM8pwS0Xz0gojcDlSvtLb7lKHIS9eue7B7RgG27gHZAmUlJaFKczq_ZDg_hFnjdB26nvIRRrPgRd0-j9eAMLnqkMhKy1XxwvyMvNsIvgoKf_3rOOZWs1vspPvenKPUE7voyIL1S3s3PWkGNeKPKGJsxe7DxKiCOaXLHDinG35mR6tMEEW8RR-/s320/20220411_101213.jpg" width="320" /></a></div></div><div style="text-align: center;"><span style="font-family: verdana;">The electronics modules for my Gamma Dogs - 3 are based on Version 3 Hardware and one unit (used as a Spare/Backup) - is a prototype based on the older Version 2 hardware.</span></div><div><br /></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbp96Wz2F77a9StRim-HLoAWi6AxR1RpTBZpJK6rUREx3gMcOcF8OYwga2ZqhvOXhDaUWrI3p2cBHphEXrzeN3ZlhGo697gylyD6pMucSTcza6BaNzgerrsuKkM8q1OWCV7IqmB1Sot1_8jIiAkSGwhbbqluougy-7mErLpoChWjwoJRMavUSU8sJa/s2772/20220311_133010.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="2772" height="216" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbp96Wz2F77a9StRim-HLoAWi6AxR1RpTBZpJK6rUREx3gMcOcF8OYwga2ZqhvOXhDaUWrI3p2cBHphEXrzeN3ZlhGo697gylyD6pMucSTcza6BaNzgerrsuKkM8q1OWCV7IqmB1Sot1_8jIiAkSGwhbbqluougy-7mErLpoChWjwoJRMavUSU8sJa/s320/20220311_133010.jpg" width="320" /></a></div></div><div style="text-align: center;"><span style="font-family: verdana;">My Gamma Dog pack - ready to hunt for radioactive rocks.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj57Dhen0a60aW9CMT_UrDqR6-aAsC0HFB_m2vOS8F9W4vEJElXABTObzLfC4jxuBa_nLTxUZpkFKBzUyn7_mGK50AT02lDJbsgLs9ASwhx5vMvFErza6AgsdYcqfA3o3uoSj__kUZqwbhf8cKpqvJmt7f0t2x5SWgObTGgtQG4JR-lUvEG3hvxYoR3/s2580/20220428_171923.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1824" data-original-width="2580" height="226" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj57Dhen0a60aW9CMT_UrDqR6-aAsC0HFB_m2vOS8F9W4vEJElXABTObzLfC4jxuBa_nLTxUZpkFKBzUyn7_mGK50AT02lDJbsgLs9ASwhx5vMvFErza6AgsdYcqfA3o3uoSj__kUZqwbhf8cKpqvJmt7f0t2x5SWgObTGgtQG4JR-lUvEG3hvxYoR3/s320/20220428_171923.jpg" width="320" /></a></div><span style="font-family: verdana;">An inverse color scheme option is available in firmware 3.9</span></div><div style="text-align: center;"><span style="font-family: verdana;">(Menu Selectable)<br /></span><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6LBDaDCbptQ7_GA9aQj05Jn0d4VyXl2fzk9xHkocEwUWIMMoM6LsGSJ11Ywwu4hYrmcozQjQqhaNfN7Z5JorjUxv7pEI0FJUmKsoo9wGvq2R1G1nV0mzsMeRC07TKgR0roCFLFQrzIrF6LgqIS45EDgCd2ot8uf6XpJYra3RP2LFh4SjOEYWLYZip/s2097/mount.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1175" data-original-width="2097" height="179" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6LBDaDCbptQ7_GA9aQj05Jn0d4VyXl2fzk9xHkocEwUWIMMoM6LsGSJ11Ywwu4hYrmcozQjQqhaNfN7Z5JorjUxv7pEI0FJUmKsoo9wGvq2R1G1nV0mzsMeRC07TKgR0roCFLFQrzIrF6LgqIS45EDgCd2ot8uf6XpJYra3RP2LFh4SjOEYWLYZip/s320/mount.jpg" width="320" /></a></div><span style="font-family: verdana;">The mount for the detector was designed with TinkerCad and 3D printed with 100% in-fill for maximum mechanical strength.</span><br /></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKud9codoH9iQMVB45ILFE8AH8aMy-ZU7lEwUsm0BFWhhH2axv_4vA8aIjQC7aI9m0lwGbjsndH0YJpLFRBWyVKXomQx9jj204TdCj9wGK1OzgPvfgAi--f4i9371PPNz9xsUtappqSJEO9viWq-qX2dMLSjNFS-hKFQNEOfvMZ3OgbHI9AnoqAln4/s3301/20220502_155526.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3301" height="181" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKud9codoH9iQMVB45ILFE8AH8aMy-ZU7lEwUsm0BFWhhH2axv_4vA8aIjQC7aI9m0lwGbjsndH0YJpLFRBWyVKXomQx9jj204TdCj9wGK1OzgPvfgAi--f4i9371PPNz9xsUtappqSJEO9viWq-qX2dMLSjNFS-hKFQNEOfvMZ3OgbHI9AnoqAln4/s320/20220502_155526.jpg" width="320" /></a></div><span style="font-family: verdana;">Mount is comprised of a lower cup and a top cap. A threaded feed-thru is used to secure the cup to the bottom of the pole. I used a feed-thru to reduce weight and possibly add an elastic strap to pull-down the top cap.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiY0hINNT5ov6KFkeK4jWzH1JNT9ZXZkObdBnzkLf3p5XmxsWlzsH6__k2n1plh7oyqpx1gyce8eT_PJgvzIeqB3wNGywKRPF4zjyRr3nCYYFHvFbLEpten9vqg2ivvoqg8cbGkM8VesVD9xPQwrrT8gOb5psGwfMCvj1vlFpJkMu-xZ37Mc2Fu4bTJ/s2284/20220502_154941.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2284" data-original-width="1487" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiY0hINNT5ov6KFkeK4jWzH1JNT9ZXZkObdBnzkLf3p5XmxsWlzsH6__k2n1plh7oyqpx1gyce8eT_PJgvzIeqB3wNGywKRPF4zjyRr3nCYYFHvFbLEpten9vqg2ivvoqg8cbGkM8VesVD9xPQwrrT8gOb5psGwfMCvj1vlFpJkMu-xZ37Mc2Fu4bTJ/s320/20220502_154941.jpg" width="208" /></a></div><span style="font-family: verdana;">The cap is designed with a slit for the BNC connector and cable. Cap slides over the pole and a pair of 0-rings - one on each side provide friction resistance. This facilitates easy installation or removal of the detector in just a few seconds. The friction from the o-rings is strong enough to lock the detector firmly in place.</span></div><div style="text-align: center;"><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3ZwpnV8N28PdZ_LGWvkjCZJgL2zA_OFP9hKwzsSQgvllVvnzWEL_xu_RfxBp8xH0m2QctYsdK2mcSty6h_LyOYC0o8rdhnBEFivIMGDVXg3XKTEL2fy_1S-s0XMEZpjqamhWLGk0KfZIv1-sCz7N1ER_Bl_MwfGmQtV3bw9oPjGJGs6eKGkBjCpKI/s3222/20220502_155006.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3222" height="186" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3ZwpnV8N28PdZ_LGWvkjCZJgL2zA_OFP9hKwzsSQgvllVvnzWEL_xu_RfxBp8xH0m2QctYsdK2mcSty6h_LyOYC0o8rdhnBEFivIMGDVXg3XKTEL2fy_1S-s0XMEZpjqamhWLGk0KfZIv1-sCz7N1ER_Bl_MwfGmQtV3bw9oPjGJGs6eKGkBjCpKI/s320/20220502_155006.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">If I need to remove the detector, all I need is to pull the top cap up and slide the bottom of the detector into the cup. To lock the detector in place I push the cap down and move the 0-ring right behind it.</div>The bottom cup provides additional mechanical protection to the detector housing.</span><br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgC5pBuOlcvfri_wJRQVmmLS4-0j10uUedIeb6rIhDgqoLs-hspMJtBMzi2D4xpt-oqdnLICuUpuvA1L9hIHSS-sh9Brx1D02RQsbcIm3rCO1dODACsudgDJSwzWoHg92sOwfcubh9eAIk0bdogYNJ2gCPY2HdXrBGQ2TV6_wiYZ8SxHz2BqgeZVEVe/s2818/20220502_160855.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1683" data-original-width="2818" height="191" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgC5pBuOlcvfri_wJRQVmmLS4-0j10uUedIeb6rIhDgqoLs-hspMJtBMzi2D4xpt-oqdnLICuUpuvA1L9hIHSS-sh9Brx1D02RQsbcIm3rCO1dODACsudgDJSwzWoHg92sOwfcubh9eAIk0bdogYNJ2gCPY2HdXrBGQ2TV6_wiYZ8SxHz2BqgeZVEVe/s320/20220502_160855.jpg" width="320" /></a></div><span style="font-family: verdana;">This type of mount is fully adjustable for various detector lengths and diameters up to 2". Ill probably design another set for detectors with diameter between 2" and 2.5"</span><br /><span style="font-family: verdana;"><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgifyWgo_PVlOHTtr_F9BKXPA1IRbFHvy-dYvQRXNAAZpGznhR6TAnqz1MsXKr-kDvjXNvIt3aZ-XM038RwhkUdkFj5olf8v6RVNWOlge6annOCYgejxPw5cxbG04iuZxR--HwsMMns40ao1xVM46mFTY1NMdeNn-GDgZYo2LEm37KmptXleCgITsY0/s3078/20220502_155212.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1667" data-original-width="3078" height="173" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgifyWgo_PVlOHTtr_F9BKXPA1IRbFHvy-dYvQRXNAAZpGznhR6TAnqz1MsXKr-kDvjXNvIt3aZ-XM038RwhkUdkFj5olf8v6RVNWOlge6annOCYgejxPw5cxbG04iuZxR--HwsMMns40ao1xVM46mFTY1NMdeNn-GDgZYo2LEm37KmptXleCgITsY0/s320/20220502_155212.jpg" width="320" /></a></div></div><div style="text-align: center;"><span style="font-family: verdana;">My 40x80mm NaI(Tl) compact detector in carbon-fiber housing, mounted at the end of the pole.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;"><span style="font-family: verdana; text-align: left;">P.S. This is old but here is an <a href="https://www.atlasobscura.com/articles/radioactive-mineral-rock-collectors-guide">article</a> in Atlas Obscura on radioactive mineral</span><span style="font-family: verdana; text-align: left;"> collecting (shameless self-promotion: I am quoted a couple of times and there are pictures of minerals currently in my own collection).</span></span></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-41167150616618108412022-03-16T11:10:00.007-04:002023-04-18T10:16:07.965-04:00Low-profile Scintillating detector for Gamma Dog EXP<p><span style="font-family: verdana;">For my Gamma Dog EXP (External Probe) I wanted to build small and lightweight detector to be mounted on a "Metal Detector style wand".</span></p><p><span style="font-family: verdana;">The weight is important as the detector is basically on the end of a long pole (which is great for covering larger area in a single sweep) and all of the implications from momentum and inertia of a large mass are present. The pole becomes a lever in your hand and the mass on the end of it is fighting changes in its state via momentum and inertia - according to Newton's laws it tries to stay in motion or tries to stay at rest and the results are amplified by the long arm of the lever to the operator's hand. </span></p><p><span style="font-family: verdana;">There is not much that can be done about the crystal - NaI(Tl) is a dense substance and at the end it comes to a compromise between weight and sensitivity - a plastic scintillator would be lighter but less sensitive. I decided to go with a 40 x 80 mm NaI(Tl) crystal. The length of the crystal makes it more sensitive for gammas coming radially to the canister - something which is an advantage due to the angle of the detector in relation to the ground surface (the metal detector wand on which it is mounted puts it at a fairly low angle)</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhJZKGFLrEZaJa_uBAAj0KyBGQ-AhPBS_Opm2wg44_J1Kdy3AVfZ6JAikOPAZBtshdi0QPlArQio5a_RDBIIXkgDP6piUH9E8enMQ-q79SP3E_qTELxrmuzKxPf4tCucqiGMQj3d3_gYcSB1xr9WHsAKzE6A0qfZCm2HhJ0uP8AnlixwN_nUBPPSZPX=s3042" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="3042" data-original-width="1855" height="320" src="https://blogger.googleusercontent.com/img/a/AVvXsEhJZKGFLrEZaJa_uBAAj0KyBGQ-AhPBS_Opm2wg44_J1Kdy3AVfZ6JAikOPAZBtshdi0QPlArQio5a_RDBIIXkgDP6piUH9E8enMQ-q79SP3E_qTELxrmuzKxPf4tCucqiGMQj3d3_gYcSB1xr9WHsAKzE6A0qfZCm2HhJ0uP8AnlixwN_nUBPPSZPX=s320" width="195" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">To keep the detector assembly short and light I went with a very low-profile PMT - Photonis XP6242.</span></div><div style="text-align: center;"><span style="font-family: verdana;">XP6242 has a
hybrid multiplier comprising of a very large first dynode coupled
to a foil multiplier.</span></div><div><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhCURtaTT3pJq1QgKCGFakMX9tkxXQnaST2qlUTtSXUxmKnBxf1Z7MShxlD0b0eoAm6XqSJe08ac793BGsOPoRrTTSFr1f5ptsqp8qQx3WSsdwOtWLTTBW6qv1-AhqwooLFKkMj7tOTvRSVPCuDa9xyARFibAqIcvzaubAgLLncNS7loy9faSVP3gb6=s3163" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="3163" data-original-width="1867" height="320" src="https://blogger.googleusercontent.com/img/a/AVvXsEhCURtaTT3pJq1QgKCGFakMX9tkxXQnaST2qlUTtSXUxmKnBxf1Z7MShxlD0b0eoAm6XqSJe08ac793BGsOPoRrTTSFr1f5ptsqp8qQx3WSsdwOtWLTTBW6qv1-AhqwooLFKkMj7tOTvRSVPCuDa9xyARFibAqIcvzaubAgLLncNS7loy9faSVP3gb6=s320" width="189" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">The length of the entire PMT is about 10cm with the VD board on the back</span></div><div><div style="text-align: center;"><span style="font-family: verdana;">It is a 10-stage PMT with Gain of 2.5x10^5 and supply voltage of 1000V</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEjLsMExWk50Zt6y8apm5u5y8QEJ4p5WtAuY6wJGB0WrabBTYj2hB9HU7sdB0D70lcgwjdBcoVBR-elq5YyhPI1JmusuK6ZGNtUARqHe4HOJjLutOAwViA0mHjlEB4iK-Ltr8EoA6NWsPtpPqBbikAlceMJlXvjmeYLnPl4KYSZTYIqaC6Gdf3W7xP_N=s2402" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1867" data-original-width="2402" height="249" src="https://blogger.googleusercontent.com/img/a/AVvXsEjLsMExWk50Zt6y8apm5u5y8QEJ4p5WtAuY6wJGB0WrabBTYj2hB9HU7sdB0D70lcgwjdBcoVBR-elq5YyhPI1JmusuK6ZGNtUARqHe4HOJjLutOAwViA0mHjlEB4iK-Ltr8EoA6NWsPtpPqBbikAlceMJlXvjmeYLnPl4KYSZTYIqaC6Gdf3W7xP_N=s320" width="320" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">The photocathode's diameter is 48mm and the overall PMT diameter is 51mm which works out perfectly for a 40x80mm crystal. Photocathode is larger than the optical interface window of the crystal's housing which means no photons will be wasted. The size difference is small too - the canister's outside diameter is 46mm and the PMT outside diameter is 51mm which means there is no need for centering collar - just a few turns of electrical tape on the crystal's housing will equalize the size difference.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEgMBblPIEsValsY1Qx10zvMwOaIfQ2sQE4oXKdqlkd0iS3ZIMrzCrJXFkwQ58jpoiN53eap9vaCDBETAyQSV_cEuTx8ELL-xFefBdt_HdxGctfIDQQAZ28AMiWYodtSdZfuB_blbW5DRzhBq1rAdFQfIgaK8AGMgRegYUzYz4-sV1WdmntvZ_5ojnuK=s1926" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1926" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/a/AVvXsEgMBblPIEsValsY1Qx10zvMwOaIfQ2sQE4oXKdqlkd0iS3ZIMrzCrJXFkwQ58jpoiN53eap9vaCDBETAyQSV_cEuTx8ELL-xFefBdt_HdxGctfIDQQAZ28AMiWYodtSdZfuB_blbW5DRzhBq1rAdFQfIgaK8AGMgRegYUzYz4-sV1WdmntvZ_5ojnuK=s320" width="310" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">The Voltage Divider was made with 2R (K-Grid and Grid-D1) and R between the dynodes. I used 4.7M for R and 9.4M for the 2R</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhnRjfWL0fzSYGa6t-b1nTdkSssWcfvO-KI-BYl5-_So4FQzwwrBK9O8e4d8GMEObzCkuo-dyoNSnR8TFwWfFqGtvDLlvePraEL6o08mzrydujfjRMdxOwj_x1tju9OISKi2TfH7Uuf2TCJ1BKSRm8H0oeCPRYLFgm_zRXKdStXXjA_iG3gZ8uJbLm8=s2749" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2749" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/a/AVvXsEhnRjfWL0fzSYGa6t-b1nTdkSssWcfvO-KI-BYl5-_So4FQzwwrBK9O8e4d8GMEObzCkuo-dyoNSnR8TFwWfFqGtvDLlvePraEL6o08mzrydujfjRMdxOwj_x1tju9OISKi2TfH7Uuf2TCJ1BKSRm8H0oeCPRYLFgm_zRXKdStXXjA_iG3gZ8uJbLm8=s320" width="217" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">Since there is no standard 9.4M resistor value for the 2R resistors and the PCB pads are just for a single resistor, I had to use the "tent" mounting technique for these resistors. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The total VD impedance is 65.8M - this is high enough to minimize voltage drop and works well with Gamma Dog's HV supply while improving SNR in case I use it for spectroscopy.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEikl0A4SzT0SMxQcBKmWS47_8-Q32UOhr0Ku_GGtSM_U13rQg0yQxM5x16TCfrraZfXOBLzd8g_0rEGosiwYlsznFyQlO7dPJNQYR9GIq-LA_J9-rXTiTTkcoFj1nxtxdllABa3HkSz5JfuPbyhKj7CmVwnErdXVAzzIjjSt_I7uWFKBXKw2OWWk_Yb=s2221" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1850" data-original-width="2221" height="267" src="https://blogger.googleusercontent.com/img/a/AVvXsEikl0A4SzT0SMxQcBKmWS47_8-Q32UOhr0Ku_GGtSM_U13rQg0yQxM5x16TCfrraZfXOBLzd8g_0rEGosiwYlsznFyQlO7dPJNQYR9GIq-LA_J9-rXTiTTkcoFj1nxtxdllABa3HkSz5JfuPbyhKj7CmVwnErdXVAzzIjjSt_I7uWFKBXKw2OWWk_Yb=s320" width="320" /></span></a></div><span style="font-family: verdana;">The VD board installed on the back of the PMT.</span></div><div style="text-align: center;"><span style="font-family: verdana;"> A machined rear cap with a female BNC connector is installed over it. Before installing the cap, I soldered a strip of thin copper foil to the ground terminal and this foil is pinched between the PMT and cap, used to ground the Mu-metal magnetic shielding which also acts as an electrostatic shielding.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHjOAGbMSVDM0414vBCO7o4WHPIEYcPQk_dL4GsvWh9G8tUj9atl6O9t70blKOGhrn4NJqfRjJi4aQjedG7egli1tRQFRkk0Q7BwgqYiUxaMZgw4hvxY-gAQPspTEEsUGrJ4AYOhXH6WLMTyRU8euyNk85p-1xI___1ZbzJRrEm9Wrg2lqSgFZKud6/s2048/20201111_142252.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1603" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHjOAGbMSVDM0414vBCO7o4WHPIEYcPQk_dL4GsvWh9G8tUj9atl6O9t70blKOGhrn4NJqfRjJi4aQjedG7egli1tRQFRkk0Q7BwgqYiUxaMZgw4hvxY-gAQPspTEEsUGrJ4AYOhXH6WLMTyRU8euyNk85p-1xI___1ZbzJRrEm9Wrg2lqSgFZKud6/s320/20201111_142252.jpg" width="250" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">These "long" NaI(Tl) crystals are used mainly for oil logging - size is 40 x 80mm. </span></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjImf_Jkkz9RGYwqJudnLASM7nIyRELViMYZ-cd_JIN7dIIHVAEjJEYuB6kx5cYmXnJ7Y22TKClNoifUOsSZKQdvWdeyYUFy36fI_stKhAZJgDk-PoU9yzAytXTuDUBxSfhTakqyUqNhKxU8IC8B39Fcy8burnhRxgIl-5NWJn97e1NtJP1BJNhEFWn/s2048/20201111_142330.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1375" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjImf_Jkkz9RGYwqJudnLASM7nIyRELViMYZ-cd_JIN7dIIHVAEjJEYuB6kx5cYmXnJ7Y22TKClNoifUOsSZKQdvWdeyYUFy36fI_stKhAZJgDk-PoU9yzAytXTuDUBxSfhTakqyUqNhKxU8IC8B39Fcy8burnhRxgIl-5NWJn97e1NtJP1BJNhEFWn/s320/20201111_142330.jpg" width="215" /></a></div><span style="font-family: verdana;">Typical NOS Soviet-Era type crystal - nice and clear with no yellowing and blemishes. In Spectroscopy mode the resolution is better than 7%. Gamma Dog shows approximately half of the count rate of a 63 x 63mm crystal for natural background.</span> <br /><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;">The rest of the assembly process is straightforward - cleaning with Acetone both optical surfaces (crystal's window and PMT's photocathode window), applying optical interface solution (viscous silicone fluid) between the crystal's window and PMT, cap on the back with BNC connector, electrical tape, grounded mu-metal sheet (connected to ground with copper tape in order to double as an electrostatic shield for the PMT), a few turns of Mu-Metal around PMT overlapping the photocathode and VD board and then more electrical tape and foam.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhWyE9bGUuaHQ08I4PBmCACKEIpRPF2Ym6aygv18JTqPhsq4W8kOQWgPeeg4xdqSxY4e-vOKQXgQ7gRUI42nYHirY1I4PbO1TANSKUvNaT1TLc30lJH3tLZH028YpXq_Bs2hBUiZT4U7HYTmPFlMJCprneiT_XhVouOSGSnohyOQa4LlifZ1hwL2k-J=s2535" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2535" data-original-width="1435" height="320" src="https://blogger.googleusercontent.com/img/a/AVvXsEhWyE9bGUuaHQ08I4PBmCACKEIpRPF2Ym6aygv18JTqPhsq4W8kOQWgPeeg4xdqSxY4e-vOKQXgQ7gRUI42nYHirY1I4PbO1TANSKUvNaT1TLc30lJH3tLZH028YpXq_Bs2hBUiZT4U7HYTmPFlMJCprneiT_XhVouOSGSnohyOQa4LlifZ1hwL2k-J=s320" width="181" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">For the detector housing I wanted something strong and lightweight, and the choices I had were Titanium or carbon-fiber tube. </div></span></div><div style="text-align: center;"><span style="font-family: verdana;">I went with a Carbon Ffiber tube with OD 64mm and 2mm wall thickness. The detector assembly needed only one thin layer of closed-cell rubber foam to fit inside the tube - just like in a glove.</span></div><div><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEh7jWTr67-CVfxSZmZVnanbM564O18JfYqXXKRWvQmdR72zaFT5fiRf4P6Fuv2XmVyvgywodLa1D9MHd5_PJioA2g5DBNpHcLjfrbvlWsX1P6EMIUMhcbPkZX3g09aD4D1x_HEvJoA7iI9Cb4RuyeuXibbn8HHo-zDs37xexG6USjEcTluiSq6WqqAB=s2216" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="981" data-original-width="2216" height="142" src="https://blogger.googleusercontent.com/img/a/AVvXsEh7jWTr67-CVfxSZmZVnanbM564O18JfYqXXKRWvQmdR72zaFT5fiRf4P6Fuv2XmVyvgywodLa1D9MHd5_PJioA2g5DBNpHcLjfrbvlWsX1P6EMIUMhcbPkZX3g09aD4D1x_HEvJoA7iI9Cb4RuyeuXibbn8HHo-zDs37xexG6USjEcTluiSq6WqqAB=s320" width="320" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">Two 3D printed caps are used to close off the detector assembly.</span></div><div style="text-align: center;"><span style="font-family: verdana;">The design of the caps is such, that the carbon fiber tube is inserted in a precisely sized groove in each cap. There is a beveled inner edge on the top cap sealing the enclosure against the inner detector cap.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEgiZoOFMPjvlFBbxSY6qZF5Y8tF1VrjlPeqUZC6yLh4pC2vvdjgn_lO3yCOcPqdjyXYdUI5U2byEdGqDKdvCSaJ_NXnewkIMnrMd0HMS-hLOLja2U9N8-rUd1Fba3YrklIXskZ-kAv1mZNCmSZNqb7e2aAFpfuS037Q_w2C9reCsn2q09byUzaPhWIV=s3118" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1752" data-original-width="3118" height="180" src="https://blogger.googleusercontent.com/img/a/AVvXsEgiZoOFMPjvlFBbxSY6qZF5Y8tF1VrjlPeqUZC6yLh4pC2vvdjgn_lO3yCOcPqdjyXYdUI5U2byEdGqDKdvCSaJ_NXnewkIMnrMd0HMS-hLOLja2U9N8-rUd1Fba3YrklIXskZ-kAv1mZNCmSZNqb7e2aAFpfuS037Q_w2C9reCsn2q09byUzaPhWIV=s320" width="320" /></span></a></div><span style="font-family: verdana;"><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEi4P4X7FpXu00oqbZqNCmj9hr2QRuMiP0HBjs59DXDpYrpgofaOAd0tmL9YA8sk1-b4SSCmcn8y_dvQ0ZWR-rDP81rScDSA9FUhcL7_wp8C6HKNbU84pjbuXQSuAEaDthKm331oItlkRHOp9T9mAPI1yIP7BNL-m7wBJj7rGbBnaT3yoV0Phc3_i3Mt=s3123" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1755" data-original-width="3123" height="180" src="https://blogger.googleusercontent.com/img/a/AVvXsEi4P4X7FpXu00oqbZqNCmj9hr2QRuMiP0HBjs59DXDpYrpgofaOAd0tmL9YA8sk1-b4SSCmcn8y_dvQ0ZWR-rDP81rScDSA9FUhcL7_wp8C6HKNbU84pjbuXQSuAEaDthKm331oItlkRHOp9T9mAPI1yIP7BNL-m7wBJj7rGbBnaT3yoV0Phc3_i3Mt=s320" width="320" /></span></a></div><span style="font-family: verdana;"><br /></span><div style="text-align: center;"><span style="font-family: verdana;">The caps are glued with RTV sealant and provide dust and water resistance to the detector.</span></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-25289959298093065862021-10-26T14:53:00.171-04:002023-09-08T09:46:06.455-04:00Gamma Dog - The Ultimate Radioactive Rock / Mineral Finder!<p><span style="font-family: verdana;">A friend of mine and an avid REE mineral collector Charles Young designed some time ago an instrument intended specifically for finding radioactive rocks "in the wild". The design evolved from his initial concept to become a pretty clever and viable solution. Charles and I have been talking for a while, exchanging thoughts and ideas what such instrument should be and what features are needed. Finally, Charles managed to do something I've been thinking about for years but never really had the time or the proper motivation to dive into! His work was truly an inspiration for me and eventually precipitated as the "Gamma Dog project" as I realized I am not alone in my ideas to create a radioactive rock-finder.</span></p><p><span style="font-family: verdana;">With the core R&D work done by Charles, we decide to collaborate in the design efforts and improve both, the hardware and software side in order for this instrument to become the <b>Ultimate tool for the Radioactive Rockhound.</b></span></p><p><span style="font-family: verdana;">Currently, there are no such specialized prospecting tools as the Gamma Dog on the market. The glory days of Uranium and REE prospecting are long gone! Consumer grade radiation detection is reduced mainly to inexpensive Geiger counters and dosimeters. The few commercial detectors intended for professional use by geologists are extremely expensive yet lacking some important for us functionality.</span></p><p><span style="font-family: verdana;">Geiger Counters are more or less useless for mineral collecting due to their poor gamma ray sensitivity and commercial scintillators on the other hand, require that your eyes are "glued" to the meter's scale in order to monitor for a detected rate increase or you have to listen to a divided click-rate and trying to figure out if the click rate changes, just "by ear", which is a pretty strenuous activity by itself. </span></p><p><span style="font-family: verdana;"><b>We wanted an instrument that is simple to use, very sensitive and the UI to allow for the user to focus on the environment / terrain and not on the instrument itself. The goal was to design a device that is really intuitive to use, and to make the activity of radioactive rock hunting more enjoyable than simply staring at a meter, while waiting for the needle to jump or a number on display to increase.</b> </span></p><p style="text-align: center;"><span style="font-family: verdana;">Meet the </span><span><span style="font-family: trebuchet; font-size: large;">γ</span><span style="font-family: verdana;">Dog! </span></span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtdZd8jpDC3sBC7wfAxLIAEYUzpDFE-9SJxSmsGcxOfMPPKSSBbGm0tervxdD7cwXkHTwlPBpORGs_-kUoKEJEe3W12p9JcoCXBlkNyt0aaUGRX_Ea56amfk9L55vn7u4OgNDMvBmaGidDbPXpmOjgCONMxjYgjtT9l5o59TH9F-XEFptPoqwXd_Hp/s2588/20220430_121820.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2588" data-original-width="1530" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtdZd8jpDC3sBC7wfAxLIAEYUzpDFE-9SJxSmsGcxOfMPPKSSBbGm0tervxdD7cwXkHTwlPBpORGs_-kUoKEJEe3W12p9JcoCXBlkNyt0aaUGRX_Ea56amfk9L55vn7u4OgNDMvBmaGidDbPXpmOjgCONMxjYgjtT9l5o59TH9F-XEFptPoqwXd_Hp/s320/20220430_121820.jpg" width="189" /></a></div><br /><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The instrument's housing is a 14.5" long, 4" diameter ABS plastic tube with two end-caps, a handle, two attachment points and a control panel located on the top cap. </span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Weight is ~5.5 Lbs when equipped with 63 x 63mm NaI(Tl) scintillation crystal detector. </span></div><p style="text-align: center;"><span style="font-family: verdana;">I think, the instrument's look is a bit ominous, and I'll probably need to dress it a bit with some decals for the sake of the general public. After all, you press a red, backlit button on a big, black, cylindrical object - it beeps and the first thing you see on the display is the radiation trefoil, followed by changing numbers - I can see how an ignorant or less intelligent person could hyperventilate seeing this.</span></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-5J69hGynXVE/YaLRZiCMWBI/AAAAAAAARF8/f0k2a9RPSuIKeCjRLP-umAsudeMyqLRsACLcBGAsYHQ/s1943/Gamma_Dog_Internals.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1943" data-original-width="920" height="320" src="https://1.bp.blogspot.com/-5J69hGynXVE/YaLRZiCMWBI/AAAAAAAARF8/f0k2a9RPSuIKeCjRLP-umAsudeMyqLRsACLcBGAsYHQ/s320/Gamma_Dog_Internals.jpg" width="152" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana; text-align: left;">The 3 major internal components are the scintillating detector, the electronics package (which includes an advanced microcontroller, pulse amplifier and HV power supply, along with other boards and components) and the 6600 mAh LiPo rechargeable battery (there is also a coaxial cable interconnect between the electronics and the detector).</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana; text-align: left;">The scintillating detector is heavily padded with closed-cell rubber foam ("Neoprene") to protect the delicate crystal and PMT from any mechanical shocks and vibrations and to provide thermal stability for the crystal. The unit can accommodate different LiPo battery sizes - usually 2x18650 cells in parallel (4400 mAh) or 3x18650 cells in parallel (6600 mAh). The bottom ABS cap is solvent-welded, and it is water-tight. The top cap is removable (3x SS Screws) and hosts the entire electronics module and control panel.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana; text-align: left;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-OdXTlZ3I3dc/YZhwanDrcPI/AAAAAAAARCE/MHrHtsrJrhEcMzApm0-gjELEX4VhPT1JACLcBGAsYHQ/s2048/20211118_194716.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1377" data-original-width="2048" height="215" src="https://1.bp.blogspot.com/-OdXTlZ3I3dc/YZhwanDrcPI/AAAAAAAARCE/MHrHtsrJrhEcMzApm0-gjELEX4VhPT1JACLcBGAsYHQ/s320/20211118_194716.jpg" width="320" /></a></div></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The Latching Relay board (left) and </span><span style="font-family: verdana;">MCU board (middle) </span><span style="font-family: verdana;">are stacked on the motherboard (right) headers. Visible between the headers are the 12-bit DAC and 4K EEPROM daughter boards. The red solder mask PCB is the HV power supply, pulse amplifier and decoupling circuit.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Currently, I am prototyping the latest version (v3) of the Gamma Dog. I designed the PCB with AutoCAD Eagle, and the fabrication was done through the OSHPark service - the PCBs came out absolutely superb with a beautiful purple solder-mask and gold-plated pads and vias! Highly recommend OSHPark for small projects - quality, pricing and ordering process is simply fantastic!</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-PRuCjqSaSGs/YZhxGiPwuFI/AAAAAAAARCM/Wvik_sWpMgU8ZUa9bp1VHcDCvYUkfB4fwCLcBGAsYHQ/s2048/20211118_192852.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="2038" height="320" src="https://1.bp.blogspot.com/-PRuCjqSaSGs/YZhxGiPwuFI/AAAAAAAARCM/Wvik_sWpMgU8ZUa9bp1VHcDCvYUkfB4fwCLcBGAsYHQ/s320/20211118_192852.jpg" width="318" /></a></div><span style="font-family: verdana;">The new hardware version expands on the v2 PCB with a second control button for an improved UI, 4K EEPROM for storing settings and internal data and a 12-bit DAC for digitally adjusting the value of the Pulse Height Threshold.</span><br /></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-NhTMvwyMKks/YZ0cBJx_o-I/AAAAAAAARE0/3yK6M818FeceNZX9BRZIp8T03e5pyVeQwCLcBGAsYHQ/s2048/20211122_123719.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1711" data-original-width="2048" height="267" src="https://1.bp.blogspot.com/-NhTMvwyMKks/YZ0cBJx_o-I/AAAAAAAARE0/3yK6M818FeceNZX9BRZIp8T03e5pyVeQwCLcBGAsYHQ/s320/20211122_123719.jpg" width="320" /></a></div><span style="font-family: verdana;">There is an RFI can for shielding the HV circuit with hole to access the HV Adj. Potentiometer - the red board on the right (the RF shield is yet to be installed on this picture).</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">There are 6 connectors on the motherboard - one female BNC for connecting the scintillator and 5 others for the power source, buttons, display module, amplifier / speaker board and LEDs (4 connectors are mounted on the top side of the board) - not counting the IPX to SMA coaxial connection.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Not pictured here is the latching relay FeatherWing which plugs into the top MCU headers.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Stacking the boards in 4 distinctive levels allows for a more efficient use of space, while staying with the footprint of the 4" end-cap. <br /></span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><p></p><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/WujjeSRiiFk" width="320" youtube-src-id="WujjeSRiiFk"></iframe></div><div style="text-align: center;"><span style="font-family: verdana;">A quick demonstration of the "<span style="font-family: trebuchet; font-size: large; text-align: left;">γ</span>Dog v2 PLUS" prototype and the UI.</span></div><div style="text-align: center;"><span style="font-family: verdana;">(Youtube <a href="https://youtu.be/WujjeSRiiFk">link</a>)</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;"><b>Hardware Features:</b></span></div><div style="text-align: center;"><br /></div><div style="text-align: left;"><span style="font-family: verdana;">Most of the instrument's housing is occupied by the padded scintillator (see the diagram above). There is also a battery "compartment", and the entire electronics assembly is located in the top end-cap. A fixed metal handle with a soft nylon strap handle and a a couple of special finger pulls / attachment points facilitate easy handling and maneuvering of the instrument while searching and digging. The enclosure is sealed and waterproof up to the control panel so it can be partly submersed if needed. The control panel is water-resistant and can withstand occasional splash of mud, water or light rain and it is easily protected with a transparent plastic "shower cap" and a rubber band when weather conditions deteriorate severely. There is 1/4" thick Plexiglass bezel protecting the display.</span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div style="text-align: left;"><ul style="text-align: left;"><li><span style="font-family: verdana;"><span> </span>Large (63x63mm NaI(Tl) crystal) Scintillating detector - this is the detector I previously built, but <b>almost any NaI(Tl) / CsI (Tl) / CsI (Na)</b> scintillating detector can be used or even <b>Bicron BC408/BC412</b> Plastic scintillators. Requirements are a voltage divider impedance of 50M-120M, common signal / PMT HV bias line and voltage up 1000V - Ludlum 44-2 probe for example is one possible "off-the-shelf" solution.</span></li></ul><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-LZ5JXKeBQHI/YUtQrPZ03XI/AAAAAAAAQog/i0_8z8t-5cMnmXcdlGp8odaeJasM3vXJgCPcBGAYYCw/s2048/20210918_154956.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1259" height="320" src="https://1.bp.blogspot.com/-LZ5JXKeBQHI/YUtQrPZ03XI/AAAAAAAAQog/i0_8z8t-5cMnmXcdlGp8odaeJasM3vXJgCPcBGAYYCw/s320/20210918_154956.jpg" width="197" /></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;"><span style="text-align: left;">It was time to put my </span><a href="http://blog.kotarak.net/2021/09/bigger-is-better-or-building-larger.html" style="text-align: left;">newly built</a><span style="text-align: left;"> large NaI(Tl) scintillator to work. </span></span></div><div style="text-align: center;"><span style="font-family: verdana;"><span style="text-align: left;"><br /></span></span></div>My large 63 x 63 mm NaI(Tl) detector is the "heart" of the <span style="font-family: trebuchet; font-size: large; text-align: left;">γ</span>Dog and covers the "traditional" for NaI(Tl) detectors Gamma Rays energy range of 25keV to 3000 keV. The larger the crystal is, the more efficient and sensitive the instrument is going to be - this is critical when looking for radioactive specimens "in the wild", which can have very weak emissions due to the shielding effects of soil and rocks and/or low N.O.R.M. content. Smaller size detectors or scintillating plastic detectors on the other hand are better when searching in tailings piles, mine dumps or inside mines, where the radioactivity is abundant to begin with.</span><span style="font-family: verdana;"><br /></span></div><ul style="text-align: left;"><li><span style="font-family: verdana;"><span> </span>Adjustable, regulated and filtered, boosted High-Voltage Power Supply for the PMT Bias, positive polarity, outputting in the 600V-1000V range with 4V input. The low-voltage supply rails of the HV PS is controlled with a latching relay for a reduced power consumption.</span></li></ul><div><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-uhKIhyPziwg/YX2zkRPHUCI/AAAAAAAAQ8Y/q1Kr2TiNOTgvvMpngD1PkuQ2lR_ockOegCLcBGAsYHQ/s2048/20211001_102857.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1152" data-original-width="2048" height="180" src="https://1.bp.blogspot.com/-uhKIhyPziwg/YX2zkRPHUCI/AAAAAAAAQ8Y/q1Kr2TiNOTgvvMpngD1PkuQ2lR_ockOegCLcBGAsYHQ/s320/20211001_102857.jpg" width="320" /></a></div><span style="font-family: verdana;"><span style="font-family: trebuchet; font-size: large; text-align: left;">γ</span>Dog's High-Voltage Power Supply and Pulse Shaping Amplifier.</span></div><ul style="text-align: left;"><li><span style="font-family: verdana;"><span> </span>Pre-amplifier with adjustable gain ratio and adjustable pulse shape - rise/decay time-constants as well as decoupling capacitor and load resistor are all hosted on the HV board as well.</span></li><li><span style="font-family: verdana;"><span> Adjustable minimum pulse level detection </span></span><span style="text-align: center;"><span style="font-family: verdana;">threshold using a comparator on the input of the MCU to "digitize" the scintillator pulses for counting.</span></span></li></ul><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-QrQLwFpYExc/YZUGiTpnRII/AAAAAAAARBU/QErBBa1vmAklNq_f5eiuEmzVi9RRfKdOQCLcBGAsYHQ/s2048/20211116_204231.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1384" data-original-width="2048" height="216" src="https://1.bp.blogspot.com/-QrQLwFpYExc/YZUGiTpnRII/AAAAAAAARBU/QErBBa1vmAklNq_f5eiuEmzVi9RRfKdOQCLcBGAsYHQ/s320/20211116_204231.jpg" width="320" /></a></div><span style="font-family: verdana;">The scintillator pulses as they are amplified (yellow trace) are "digitized" by the comparator (blue trace) when they exceed the preset voltage threshold (white cursor trace on the Y axis).</span><br /></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-Uc1B6gU3Xs4/YX2leQ00RfI/AAAAAAAAQ8Q/s2-gb4gbvx4XdW8vm4dS9YlzEjMz6_GuQCLcBGAsYHQ/s2048/20211030_155612.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1742" height="320" src="https://1.bp.blogspot.com/-Uc1B6gU3Xs4/YX2leQ00RfI/AAAAAAAAQ8Q/s2-gb4gbvx4XdW8vm4dS9YlzEjMz6_GuQCLcBGAsYHQ/s320/20211030_155612.jpg" width="272" /></a></div><span style="font-family: verdana;">Nordic nRF52840 System on a Chip is the "brains" of <span style="font-family: trebuchet; font-size: large; text-align: left;">γ</span>Dog.</span><br /><span style="font-family: verdana;"><br /></span></div><ul style="text-align: left;"><li><span style="font-family: verdana;"><span> </span>Nordic nRF52840 SoC (installed on the Adafruit Feather Sense Board) - ARM Cortex M4F processor, 1MB Flash and 256K SRAM, 21 GPIO, 6 x 12-bit ADCs, up to 12 PWM outputs and an array of </span><span style="font-family: verdana;">environmental </span><span style="font-family: verdana;">sensors - Accelerometer, Temperature, Humidity, Magnetometer, Barometric pressure, etc. as well as Bluetooth LE connectivity.</span></li><li><span style="font-family: verdana;"> Amplified (Class D amplifier) panel-mounted 1W speaker with manually adjustable volume</span></li><li><span style="font-family: verdana;"><span> 3</span> backlit buttons (Power, Squelch, Display Mode) with indicator LEDs</span></li><li><span style="font-family: verdana;"><span> </span>High-contrast, ultra-low power SHARP Memory eInk graphics display (144 x 168 pixels)</span></li><li><span style="font-family: verdana;"><span> Rugged Micro-</span>USB port (/w protective cap) for battery charging and firmware updates. Use-while-charging with an external 5V USB battery pack is also possible. </span></li><li><span style="font-family: verdana;"><span> Built-in LiPo battery charge controller with 200mA charge current</span></span></li><li><span style="font-family: verdana;"><span><span> </span></span></span><span style="font-family: verdana;">6600 mAh / 3.7V LiPo Battery (or 3x 18650 cells in parallel) which provides up to 24 hours of continuous run time. Smaller capacity battery can also be used - 2x18650 (4400 mAh) and will still provide a full day of continuous operation while reducing the weight.</span></li><li><span style="font-family: verdana;">BLE or Low Energy Bluetooth connectivity for outboard data processing and storage (on a Smartphone or PC)</span></li><li><span style="font-family: verdana;">Configurable BT power levels</span></li></ul></div></div><div><p style="text-align: center;"><b style="font-family: verdana;">Software Features:</b></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-V_85DCShdYE/YX_xRdHYXmI/AAAAAAAAQ9Q/A8vmkZj1irMpMwQy1hkakPZo3rSb_JSgACLcBGAsYHQ/s2048/20211031_141301.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="2048" height="320" src="https://1.bp.blogspot.com/-V_85DCShdYE/YX_xRdHYXmI/AAAAAAAAQ9Q/A8vmkZj1irMpMwQy1hkakPZo3rSb_JSgACLcBGAsYHQ/s320/20211031_141301.jpg" width="320" /></a></div><p></p><p><span style="font-family: verdana;">There are a couple of novel features which make this instrument different than anything else out there - <i><b>the count-rate based variable frequency tone feedback coupled with an</b></i></span><span style="font-family: verdana;"><i><b> adjustable level squelch control</b></i></span><span style="font-family: verdana;"><i>.</i> Both features are aimed at easy detection and location of radioactive sources. </span></p><p><span style="font-family: verdana;">Listening to slow clicks while trying to adjust to the background count rate in order to detect any changes when radiation is detected is way too strenuous on the brain - changes in the pitch of a tone on the other hand are picked up immediately and very easy to follow. The squelch control on the other hand makes the instrument "vocal" only when needed, near a radioactive source above background level.</span></p><p><span style="font-family: verdana;">Gamma Dog is running on almost 3000 lines of code (firmware V3.9.2)</span></p><div style="text-align: left;"><ul style="text-align: left;"><li><span style="font-family: verdana;"> Audio is main method of feedback via the variable frequency tone and alert beeps.</span></li><li><span style="font-family: verdana;"><span> </span>Super-simple and responsive 2 buttons UI with click, double-click and long-press actions (all with audible feedback) to execute various actions such as Sql Level Adjustment, Auto-Set, etc. </span></li><li><span style="font-family: verdana;"><span> </span>2 user-selectable persistent display modes - Current Rate and Rate vs. Time Histogram. </span></li><li><span style="font-family: verdana;">In the Rate mode, single-click of the Squelch button will increase the squelch level and double-click will decrease the level. Audio frequency will increase 10Hz for each 10 CPS and displays shows numerical count rate.</span></li><li><span style="font-family: verdana;"> In the Histogram mode - display shows 140 seconds scrolling count-rate histogram and double-click will toggle between constantly open Squelch and Normal Squelch Control. In addition, in this mode the audio is generated with smaller (5Hz) steps per 10 CPS. This mode can be useful when searching in places with many high-activity sources like mine dumps / tailings. etc. as very high rates will keep the audio frequency half of the rate - i.e., 4000 CPS will result in ~2kHz tone when squelch level is set really low.</span></li><li><span style="font-family: verdana;"><span> </span>2 indicator LEDs - Green Squelch button LED flashes when the number of counts reaches 2x the squelch setting counts and also indicates the startup sequence point for Histogram mode change, Red Power button LED indicates sleep status / HV power off (when blinking) and normal operation (solid glow)</span></li><li><span style="font-family: verdana;"><span> Graphics display shows Firmware version, Internal Diagnostic results and alerts, Current Count Rate in CPS (refreshed every second, resolution 10 CPS) or a count-rate rolling histogram, battery level as voltage and percentage of capacity (refreshed every minute), Current Squelch Level Setting, Count Overflow and Low Battery Alerts.</span></span></li></ul><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-frqSiEUOyPE/YX_wN_Iu-_I/AAAAAAAAQ80/VXkJHpJknLE5E1dZwfBSDh_S0R1ALsGtgCLcBGAsYHQ/s2048/20211031_121617.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="2048" height="320" src="https://1.bp.blogspot.com/-frqSiEUOyPE/YX_wN_Iu-_I/AAAAAAAAQ80/VXkJHpJknLE5E1dZwfBSDh_S0R1ALsGtgCLcBGAsYHQ/s320/20211031_121617.jpg" width="320" /></a></div><span style="font-family: verdana;">One of my contributions to the project was the development of the display interface and the firmware code for it, including the UI. <span style="font-family: trebuchet; font-size: large; text-align: left;">γ</span>Dog PLUS uses 1.3" Ultra-Low Power SHARP Memory display (144 x 168 pixels, same kind as the one used in the Pebble Watch). The display is a very high contrast eInk type, super-easy to read in direct sunlight, recessed in the front panel for mechanical protection and it shows useful information improving on the ergonomics and the interaction with the instrument.</span></div><div style="text-align: center;"><span style="font-family: verdana;">Data on the display is refreshed every second for the Count Rate readout and every minute for Battery-related information.<br /></span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-_-CgdaLxkFM/YX_w2KUmCdI/AAAAAAAAQ9E/dMMIa3olTicT_YueH4I_gsZ_XePrC2EXQCLcBGAsYHQ/s2048/20211031_124143.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1947" height="320" src="https://1.bp.blogspot.com/-_-CgdaLxkFM/YX_w2KUmCdI/AAAAAAAAQ9E/dMMIa3olTicT_YueH4I_gsZ_XePrC2EXQCLcBGAsYHQ/s320/20211031_124143.jpg" width="304" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Battery Voltage, Current Battery capacity and Internal Diagnostics Status</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_v9HTlfFlkWf2x3DEZnKZYL0dk7e_HS_UZ5syak4aloUAZ7GxOz5fgimXTRWYCI4m2r2eyIR0CJSpCS7URRV-hB6iLkRVwtVP0BYwEZ3eIiHdVLdFzhriz3B1HL1cenbJDnrkLnBNGznaRrEl94ARzylQFyHnR9zK9dbYdyQuHPCDmjrsocexWb3I/s1655/20230330_093449.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1655" data-original-width="1654" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_v9HTlfFlkWf2x3DEZnKZYL0dk7e_HS_UZ5syak4aloUAZ7GxOz5fgimXTRWYCI4m2r2eyIR0CJSpCS7URRV-hB6iLkRVwtVP0BYwEZ3eIiHdVLdFzhriz3B1HL1cenbJDnrkLnBNGznaRrEl94ARzylQFyHnR9zK9dbYdyQuHPCDmjrsocexWb3I/s320/20230330_093449.jpg" width="320" /></a></div><span style="font-family: verdana;">Internal Temperature and Relative Humidity</span><br /><div class="separator" style="clear: both; text-align: center;"><br /></div></div><ul style="text-align: left;"><li><span style="font-family: verdana;"><span><span> Internal diagnostic routine reports over-temperature, water intrusion (by measuring the internal air humidity level in the enclosure) and various levels of the battery condition - both visually, on the display and with a series of beeps.</span></span></span></li><li><span style="font-family: verdana;"><span><span><span><span> </span>Audible and on-screen "critical battery level" reminder - every minute when voltage drops below 10%</span></span></span></span></li><li><span style="font-family: verdana;"><span><span><span><span> On-screen Charging / Charge Complete Status Indicator</span></span></span></span></span></li><li><span style="font-family: verdana;"><span><span><span><span> Complete bootup time from Power button press to Ready to use is 12 seconds.</span></span></span></span></span></li></ul><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-BuvqSFQockw/YX_xHibxinI/AAAAAAAAQ9M/TqskLN4jhOEanqTg0mqOv7XCRnZmpYAbwCLcBGAsYHQ/s2048/20211031_121552.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2009" data-original-width="2048" height="314" src="https://1.bp.blogspot.com/-BuvqSFQockw/YX_xHibxinI/AAAAAAAAQ9M/TqskLN4jhOEanqTg0mqOv7XCRnZmpYAbwCLcBGAsYHQ/s320/20211031_121552.jpg" width="320" /></a></div></div><ul style="text-align: left;"><li><span style="font-family: verdana;"><span> <span> An Advanced Accelerometer-based PMT / Battery saver will shut down the High-Voltage Power Supply and the pulse pre-amplifier after 10 minutes of inactivity (no instrument movement) during normal operation or after 1 minute while charging the battery overnight. The normal operation resumes within 1 second of the instrument detecting a physical movement (for an example - picking it up). During normal operation the red power LED glows solid and blinks when the instrument is in Sleep Mode. I designed this feature with the use of a latching relay to further save power. Going in and out of sleep mode is accompanied by audible feedback (descending or ascending tone chirp). Current draw drops from 70 mA to 10 mA when the HV supply is powered down. The DAC is also powered down during sleep. There is also selectable "No Sleep" mode as well as "Charge and Sleep" mode.</span></span></span></li><li><span style="font-family: verdana;"><span><span> Auto-Squelch Set will sample and establish the squelch trigger level at the current sampled background radiation level during startup or when it is activated by the user with a long-press of the Squelch button.</span></span></span></li><li><span style="font-family: verdana;"> Tone frequency generation is set always to begin at the current squelch level and frequency always starts low when the squelch opens, regardless of the current rate or range of operation - this allows for the instrument to operate in a comfortable for the human ear frequency range regardless of the current measured count-rate. In other words, the lower end of the audio tone frequency range is dynamically adjusted to begin at Squelch level. </span></li><li><span style="font-family: verdana;"> Histogram Mode displays scrolling and auto-ranging relative count-rate histogram</span></li></ul><div><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-rZe7xqnJj_Y/YZLfZ3Y9ZVI/AAAAAAAARAc/r6Dqpp4mjcoXg-YFm3ClWd_dZ1Q57ZpRgCLcBGAsYHQ/s2048/20211115_151831.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1789" height="320" src="https://1.bp.blogspot.com/-rZe7xqnJj_Y/YZLfZ3Y9ZVI/AAAAAAAARAc/r6Dqpp4mjcoXg-YFm3ClWd_dZ1Q57ZpRgCLcBGAsYHQ/s320/20211115_151831.jpg" width="280" /></a></div><span style="font-family: verdana;">The scrolling count-rate vs. time histogram displays the count-rate history over the last 140 or 45 seconds. The histogram is dynamically normalized to the count-rate range over this period of time.</span></div><div style="text-align: center;"><span style="font-family: verdana;">On this picture, the minimum count rate over the past 140 seconds is the "floor" and max rate is the "ceiling".</span><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-FG_UIHegrZw/YZPe0INzVqI/AAAAAAAARBM/9FcYi2WB2EcXrTaT_fZdP0qtTsxNl_OywCLcBGAsYHQ/s2048/20211116_113731.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="2048" height="320" src="https://1.bp.blogspot.com/-FG_UIHegrZw/YZPe0INzVqI/AAAAAAAARBM/9FcYi2WB2EcXrTaT_fZdP0qtTsxNl_OywCLcBGAsYHQ/s320/20211116_113731.jpg" width="320" /></a></div><span style="font-family: verdana;">Typical background rate histogram (130 CPS to 200 CPS). </span></div><div style="text-align: center;"><span style="font-family: verdana;">The histogram is constantly updated in background at 1 sec interval and always available for the last 140 or 45 sec. It displays current statistics for the span - Min, Max and Average Rate.</span><br /></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-7loz7pnKKjs/YZPaxl2vNtI/AAAAAAAARBE/Lj-ZntYRGo43Sjq4sZA38Ya8R_AxVod1wCLcBGAsYHQ/s2048/20211116_104338.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1882" height="320" src="https://1.bp.blogspot.com/-7loz7pnKKjs/YZPaxl2vNtI/AAAAAAAARBE/Lj-ZntYRGo43Sjq4sZA38Ya8R_AxVod1wCLcBGAsYHQ/s320/20211116_104338.jpg" width="294" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">High-rate event (2560 CPS) (specimen of Uraninite), followed by drop to background level. </span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The displayed histogram is dynamically normalized every time it is drawn, to show the maximum rate peak which, on the other hand "pushes down" the background level if there is a big difference in rates.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9o3RfPZwDp-bFNNvqUePsslgEqr_pYbiLSi5YJirRdOiQ9J0y0HNUsMFonQghMK6TcAxFZzSlY3O1WC3grK2F9cvIhRGPW6q0mFtViXqZ6V9HVjEvW98Ybete1Y0RR12YG5qVSHMalbK44xhjBY8juO34eaRyxI6urB0pCjEBHe6CQYoQnwUuHV4Q/s1682/20230330_093412.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1682" data-original-width="1552" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9o3RfPZwDp-bFNNvqUePsslgEqr_pYbiLSi5YJirRdOiQ9J0y0HNUsMFonQghMK6TcAxFZzSlY3O1WC3grK2F9cvIhRGPW6q0mFtViXqZ6V9HVjEvW98Ybete1Y0RR12YG5qVSHMalbK44xhjBY8juO34eaRyxI6urB0pCjEBHe6CQYoQnwUuHV4Q/s320/20230330_093412.jpg" width="295" /></a></div><span style="font-family: verdana;">The 45 seconds histogram. This mode should be used when frequent changes in rate take place and can be set with the Config Menu System.</span><br /><span style="font-family: verdana;"><br /></span></div></div><ul style="text-align: left;"><li><span style="font-family: verdana;"><span> Response to count rate changes with a pre-set hysteresis which prevents the squelch from opening during short rate fluctuations.</span></span></li><li><span style="font-family: verdana;"><span> Excessive Count Rate / Overflow alert above 10 000 CPS (600K CPM) - the maximum rate is not really limited but the count accuracy will drop when excessively high rates are detected.</span></span></li><li><span style="font-family: verdana;"><span><span> Compensated count accuracy for overall error in counting of 0.1% (electronics only)</span></span></span></li></ul><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-xRXEgAZBk1w/YX2X00VXaaI/AAAAAAAAQ8I/k6QN-fBve9wRk26YvA5NCYxyuhSKwaYqQCLcBGAsYHQ/s1481/counting_GammaDog.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1481" data-original-width="1056" height="320" src="https://1.bp.blogspot.com/-xRXEgAZBk1w/YX2X00VXaaI/AAAAAAAAQ8I/k6QN-fBve9wRk26YvA5NCYxyuhSKwaYqQCLcBGAsYHQ/s320/counting_GammaDog.jpg" width="228" /></a></div><span style="font-family: verdana;">Test of the hardware and the software counting algorithm. Feeding the input with pulses from a function generator shows that the counting accuracy is spot-on! Maximum error is 10 CPS.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-A7DxXCcoRbQ/Yaex9nPb9gI/AAAAAAAARMM/8bPil-i-Z-02LRqn4ZdhW4oDJb8wWXT3gCLcBGAsYHQ/s2048/20211201_102106.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1536" data-original-width="2048" height="240" src="https://1.bp.blogspot.com/-A7DxXCcoRbQ/Yaex9nPb9gI/AAAAAAAARMM/8bPil-i-Z-02LRqn4ZdhW4oDJb8wWXT3gCLcBGAsYHQ/s320/20211201_102106.jpg" width="320" /></a></div><span style="font-family: verdana;">Test Setup for counting accuracy and pre-amp alignment.</span></div><div style="text-align: center;"><span style="font-family: verdana;"> Maximum count rate is up to 17K CPS (~1M CPM) for short pulses (~50 uS). Average pulse length of 100uS will allow count rate of 10K CPS (600K CPM).</span><br /></div></div><p style="text-align: center;"><span style="font-family: verdana;"> <span style="font-size: medium;"> <b>Instrument Usage</b></span></span><br /></p><p style="text-align: center;"><span style="font-family: verdana;"></span></p><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/W1Yo1FwZC5g" width="320" youtube-src-id="W1Yo1FwZC5g"></iframe></span></div><span style="font-family: verdana;"><div style="text-align: center;">Sensitivity comparison between <span style="font-family: trebuchet; font-size: large;">γ</span>Dog and a Geiger Counter - there is no contest! I know it is "Apples and Oranges" comparison but demonstrates why one would want to use a scintillating detector when rockhounding.</div></span><p></p><p style="text-align: center;"><span style="font-family: verdana;">(Youtube <a href="https://youtu.be/W1Yo1FwZC5g">link</a>)</span></p><p style="text-align: center;"><span></span></p><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/JkED55A3Y5I" width="320" youtube-src-id="JkED55A3Y5I"></iframe></div><br /><div style="text-align: center;"><span style="font-family: verdana;">Charles Young showing his field use of the standard model Gamma Dog.</span></div><div style="text-align: center;"><span style="font-family: verdana;">(no display and indicator LEDs but otherwise almost identical)</span></div><div style="text-align: center;"><span style="font-family: verdana;">(Youtube <a href="https://www.youtube.com/watch?v=JkED55A3Y5I&t">link</a>)</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><p></p><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/_3tvZDDOioM" width="320" youtube-src-id="_3tvZDDOioM"></iframe></div><p style="text-align: center;"><span style="font-family: verdana;">Prospecting for Radioactives in New Mexico - Charles Young, August 2021</span></p><p style="text-align: center;"><span style="font-family: verdana;">(Youtube <a href="https://www.youtube.com/watch?v=_3tvZDDOioM">link</a>)</span></p><p style="text-align: center;"></p><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/fKbmJ3yqn-0" width="320" youtube-src-id="fKbmJ3yqn-0"></iframe></div><div style="text-align: center;"><span style="font-family: verdana;">Prospecting for Radioactives in Southern New Mexico - Charles Young, November 2021</span></div><div style="text-align: center;"><span style="font-family: verdana;">(Youtube <a href="https://www.youtube.com/watch?v=fKbmJ3yqn-0">link</a>)</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;"><b>UPDATE: </b>development of Version 3 hardware and firmware has been completed. The UI is now using 2 buttons - it was specifically designed to improve the user-interactions and ergonomics if display output is also present. </span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgr_Q_kc20pwKO6s5UxlGFm7MkcjGY2RmqNiPvDtYwbQAgNak75vzm7iDTk2K56HcjXO48I5ELZFC9Cn_Gbuc7oL0jmaunrBo6T3NQjrMtJhDbXUMkz12T6GLjtkd0P3oxA0dqRjhfzbE4GIqzJCeb77QbM8REPCkxmhgjbCTQKzFArYEzab0Tq31wh/s1747/20230330_093642.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1747" data-original-width="1746" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgr_Q_kc20pwKO6s5UxlGFm7MkcjGY2RmqNiPvDtYwbQAgNak75vzm7iDTk2K56HcjXO48I5ELZFC9Cn_Gbuc7oL0jmaunrBo6T3NQjrMtJhDbXUMkz12T6GLjtkd0P3oxA0dqRjhfzbE4GIqzJCeb77QbM8REPCkxmhgjbCTQKzFArYEzab0Tq31wh/s320/20230330_093642.jpg" width="320" /></a></div></div><div style="text-align: center;"><span style="font-family: verdana;">The UI can now adjust the Minimum Pulse Height Threshold (PHT). This parameter along with another 16 (firmware ver. 4.3) configurable parameters are saved in the unit's EEPROM. </span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEDMFuK1BZiuuztChsQ_4TDJmkXigEFthOAT02qXRIpmyrNOLZNG4I6lehupMLApqLlTabNy5QRXr7oB1EHTbcPUdIxTD2BwTm3wf0XZRJV_N-gAWTWqfUony0kUxhVfBEDHtOmA_JGA3SWcsmX-TTCOGe3IAvllGWK4IUxC7RwaJO1pH4o-HOCblg/s2036/20230330_093724.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2036" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEDMFuK1BZiuuztChsQ_4TDJmkXigEFthOAT02qXRIpmyrNOLZNG4I6lehupMLApqLlTabNy5QRXr7oB1EHTbcPUdIxTD2BwTm3wf0XZRJV_N-gAWTWqfUony0kUxhVfBEDHtOmA_JGA3SWcsmX-TTCOGe3IAvllGWK4IUxC7RwaJO1pH4o-HOCblg/s320/20230330_093724.jpg" width="294" /></a></div></div><div style="text-align: center;"><span style="font-family: verdana;">Adjustments to the Minimum Pulse Height Threshold are done using a 12-bit Digital-To-Analog Converter (DAC) providing reference to the pulse discriminator and displayed in millivolts (accuracy is better than 1mV). Adjustment is done while the device is running in normal counting mode - this way the result of the adjustment can be evaluated immediately. </span></div><div style="text-align: center;"><span style="font-family: verdana;">There are UI coarse and fine steps while changing this value and "Quick Set" preset.</span></div><div style="text-align: center;"><span style="font-family: verdana;">During PHT calibration, 59 keV X-rays from an Am-241 source are used and the PHT value is lowered until the count rate increases rapidly, setting the minimum Gamma energy to which the instrument will respond.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/yBCbWDgpgG8" width="320" youtube-src-id="yBCbWDgpgG8"></iframe></div></div><div style="text-align: center;"><span style="font-family: verdana;">Additionally, there are 17 (for F/w 4.3) items in the Configuration Menu as well as a "Reset to Defaults" feature which re-writes the EEPROM with the factory default values.</span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-RMUw1pFMTQY/YaDnfHTcr8I/AAAAAAAARFU/kp0fdCH0CPY6U-elwt9Zz6cpg7Kp6V79wCLcBGAsYHQ/s2048/V3_Gamma_dog1.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1952" data-original-width="2048" height="305" src="https://1.bp.blogspot.com/-RMUw1pFMTQY/YaDnfHTcr8I/AAAAAAAARFU/kp0fdCH0CPY6U-elwt9Zz6cpg7Kp6V79wCLcBGAsYHQ/s320/V3_Gamma_dog1.jpg" width="320" /></a></div><span style="font-family: verdana;">The Version 3 hardware installed in the front panel cap.</span></div><div style="text-align: center;"><span style="font-family: verdana;">Only 2 connections are needed to the body of the instrument - coaxial cable with BNC connectors to the detector and a connection to the LiPo Battery pack.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;"><span style="text-align: left;">Current draw for the v3 hardware is 68mA during normal operation mode with Squelched audio and only 10 mA during Sleep mode.</span></span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-gxVDWv-n1kM/YaGaN7JrWqI/AAAAAAAARF0/lbzExvuH6F4wojxBJdpDLELZyh8WahfxgCLcBGAsYHQ/s1713/V3_Gamma_dog2a.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1500" data-original-width="1713" height="280" src="https://1.bp.blogspot.com/-gxVDWv-n1kM/YaGaN7JrWqI/AAAAAAAARF0/lbzExvuH6F4wojxBJdpDLELZyh8WahfxgCLcBGAsYHQ/s320/V3_Gamma_dog2a.jpg" width="320" /></a></div><span style="font-family: verdana;">The Blue button is the Squelch Control (UP/+), the Green button is Display Mode and Squelch Control (DOWN/-) and the Red button is the power ON/OFF switch. The user now can toggle and latch the squelch control open/close by a double-click of the Blue button. Squelch Auto-Set is activated by a Long-Press of the Blue button.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhKjyah0RD09oWDbagJTohIIbTJIp0lQ1o0bxwDoNTSyIeBi7GXSnuAssy_Nm7zMMq0K_8UiJ8xs-1U1S3AzoX8pGKPyKQMSd4oXVVUhIeDO3KavIxJya6JuCt386NpBq-YN-pex56SzY3axHnmQhDAzabIopx9xZ_hpuX_lquF3rD1REuKgBCtggpC=s2048" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1830" height="320" src="https://blogger.googleusercontent.com/img/a/AVvXsEhKjyah0RD09oWDbagJTohIIbTJIp0lQ1o0bxwDoNTSyIeBi7GXSnuAssy_Nm7zMMq0K_8UiJ8xs-1U1S3AzoX8pGKPyKQMSd4oXVVUhIeDO3KavIxJya6JuCt386NpBq-YN-pex56SzY3axHnmQhDAzabIopx9xZ_hpuX_lquF3rD1REuKgBCtggpC=s320" width="286" /></a></div><span style="font-family: verdana;">Version 2+ (/w one button UI) on the left and Version 3+ (/w two buttons UI) on the right.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;"><b>Bluetooth connectivity</b> </span></div><div style="text-align: center;"><div style="text-align: left;"><span style="font-family: verdana;">Gamma Dog is equipped with a Low Energy Bluetooth connectivity (BLE).</span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEidT68ic5AmM6xpyMIwLULhC5yVj4lKpx3EgxdbE4F89k-fhVvZ_XwKl0YudaZ1BvOokINTv6We7d1IYavpRy2_-yivi6baAcDgMf7XasraXFHueX4T4H7qz0sSixaZ1RWsnyxWnCXs5rYGo7McwCHVNQVCttUVYedKEhcCajl9bBr7EcZauW5qau-_=s1570" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1380" data-original-width="1570" height="281" src="https://blogger.googleusercontent.com/img/a/AVvXsEidT68ic5AmM6xpyMIwLULhC5yVj4lKpx3EgxdbE4F89k-fhVvZ_XwKl0YudaZ1BvOokINTv6We7d1IYavpRy2_-yivi6baAcDgMf7XasraXFHueX4T4H7qz0sSixaZ1RWsnyxWnCXs5rYGo7McwCHVNQVCttUVYedKEhcCajl9bBr7EcZauW5qau-_=s320" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana; text-align: left;">Bluetooth can be enabled/disabled from the configuration menu. On startup, Gamma Dog will automatically start advertising, waiting for connection.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana; text-align: left;"><br /></span></div></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEgBETJFEDuSxC0CCxS9V_akmLuWBXMZs8Q6_de_ou3IRClMt5x0Ec_mC-rqmMFGtLiYoC8qR3mWhvuKssLbCBqaqVxjRSzMeMs5iVmDY7iXt9_jxxXeLIjpL0PMGHJ6Hz5gsPkrAgH7tEWwzQfSeY5s5btqUvGkyVUhZidvaR-ydFwQZSg6-ygX_H-i=s1478" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1185" data-original-width="1478" height="257" src="https://blogger.googleusercontent.com/img/a/AVvXsEgBETJFEDuSxC0CCxS9V_akmLuWBXMZs8Q6_de_ou3IRClMt5x0Ec_mC-rqmMFGtLiYoC8qR3mWhvuKssLbCBqaqVxjRSzMeMs5iVmDY7iXt9_jxxXeLIjpL0PMGHJ6Hz5gsPkrAgH7tEWwzQfSeY5s5btqUvGkyVUhZidvaR-ydFwQZSg6-ygX_H-i=s320" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana; text-align: left;">5 levels of BT Tx Power can be set from -20dBm for level 1 up to +8dBm for Level 5.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana; text-align: left;">This menu item is context-sensitive and will show up in the menu only if BT is enabled.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana; text-align: left;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEg3fn_xSx3a9KApArxP1f4evujz2IwsM-hn0UDNaoZwYmFjJF6jDT7S8p4b_Wl_mXx-UVfbWOb0XvapPP_IH2BRzm_ojTkaVlySsN2V9R2kE2gbZnJlp9AJ1snHqEA4n4sISvNT_kUqKPI6w15IYe57GdIdoZ17IJveeU8cTvD1DTrgbcb7RaOzLa5X=s1662" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1436" data-original-width="1662" height="276" src="https://blogger.googleusercontent.com/img/a/AVvXsEg3fn_xSx3a9KApArxP1f4evujz2IwsM-hn0UDNaoZwYmFjJF6jDT7S8p4b_Wl_mXx-UVfbWOb0XvapPP_IH2BRzm_ojTkaVlySsN2V9R2kE2gbZnJlp9AJ1snHqEA4n4sISvNT_kUqKPI6w15IYe57GdIdoZ17IJveeU8cTvD1DTrgbcb7RaOzLa5X=s320" width="320" /></a></div><div><div class="separator" style="clear: both;"><span style="font-family: verdana; text-align: left;">There are two different BT icons, indicating in total 4 different states of the link - whether there is a currently active connection or not and whether BT data streaming is on or off.</span></div><div class="separator" style="clear: both;"><span style="font-family: verdana; text-align: left;"> Double-click of the Squelch button toggles the data logging on/off and the BT icon blinks showing Data logging is in progress.</span></div></div><div class="separator" style="clear: both;"><span style="font-family: verdana; text-align: left;">Data logging is automatically suspended during Sleep Mode and resumes on wakeup.</span></div><div><br /></div></div></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEjXAFvsVArJ9l22Fy7lrYd-Gg1iBThrdlIC7R_gdVEW-3ULk9jcXhYavgv0ajY-OotMEbgQxon1Bsn9-J1AU9gKh5fntuHlSGG46KY0lVzZJM_M80nYRiAZ66CorMaY7QWfLeIhi-kEevtpZ0mCF38Zy49-dbId5P1oiryOAxvttOq5kpoSqdpRw2eG=s1080" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="771" data-original-width="1080" height="228" src="https://blogger.googleusercontent.com/img/a/AVvXsEjXAFvsVArJ9l22Fy7lrYd-Gg1iBThrdlIC7R_gdVEW-3ULk9jcXhYavgv0ajY-OotMEbgQxon1Bsn9-J1AU9gKh5fntuHlSGG46KY0lVzZJM_M80nYRiAZ66CorMaY7QWfLeIhi-kEevtpZ0mCF38Zy49-dbId5P1oiryOAxvttOq5kpoSqdpRw2eG=s320" width="320" /></a></div></div><div style="text-align: left;"><span style="font-family: verdana;"> A string of parameters is broadcasted over BT every second and includes various internal parameters, detected current Count Rate and Squelch Level. Each data set includes a rolling counter as well.</span></div><div style="text-align: left;"><span style="font-family: verdana;"> Currently, the data can be received with the free Bluefruit Connect App in UART mode or Plotter mode. Commands can be sent back to the Gamma Dog to toggle on/off the logging mode and to stamp "Waypoints" with GPS coordinates. </span></div><div style="text-align: left;"><span style="font-family: verdana;">There are plans for development of a companion Cell Phone App which will store the received data while stamping each set with the current GPS coordinates and a timestamp. Parsing this data and converting it to Google Earth KML/KMZ format would be next logical step. Overlay over the terrain showing the path with current rate and "waypoints" of found minerals will be a pretty powerful and useful prospecting tool.</span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEiOsYL6mXNal8Opz72hcukn1E8jigVkYGlOOTpU7UNf4owB4AOosHhC1OXDnruli6M1EEzIUcwDvWHqtLXSnQULqKjk7FIcTO77kHj7pogio50j2AynW9prUo8UChmrb74ulP7ZYhPzsX0qF73-fjSjdSOF1-EIzObFRAkPXZYqE0QDcj7E5U9kDV94=s2316" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2316" data-original-width="1080" height="320" src="https://blogger.googleusercontent.com/img/a/AVvXsEiOsYL6mXNal8Opz72hcukn1E8jigVkYGlOOTpU7UNf4owB4AOosHhC1OXDnruli6M1EEzIUcwDvWHqtLXSnQULqKjk7FIcTO77kHj7pogio50j2AynW9prUo8UChmrb74ulP7ZYhPzsX0qF73-fjSjdSOF1-EIzObFRAkPXZYqE0QDcj7E5U9kDV94=s320" width="149" /></a></div><span style="font-family: verdana;">The Bluefruit Connect plotter mode shows Count Rate vs. Time Graph (orange) and Squelch Level changes (blue).</span><br /></div><div style="text-align: left;"><span style="font-family: verdana;"><b><br /></b></span></div><div style="text-align: left;"><span style="font-family: verdana;"><b>Firmware Update v3.7:</b></span></div><div style="text-align: left;"><span style="font-family: verdana;">- Added a menu-selectable <b>Sleep & Charge mode</b> - useful to charge the internal battery of the instrument from an external power source (car) or battery pack while in constant motion - during hiking or a car ride when the constant movement otherwise will prevent it from going into Sleep Mode. When this mode is activated, the Gamma Dog will startup normally, it will Auto-Set the Squelch level, but it will fall to sleep unconditionally within 12 sec of startup. The device will not wakeup due to motion in Sleep & Charge mode. Pressing any of the two buttons is the only way to wakeup it up and resume normal operation.</span></div><div style="text-align: left;"><span style="font-family: verdana;">- Added <b>Automatic<i> Squelch Auto-Set</i></b> (ASAS) mode. Useful as a "Smart Searching mode" while moving through areas with different radiation background levels. This feature reduces the need for manual squelch auto-set when searching. When this mode is activated, the Gamma Dog will automatically execute Squelch Auto-Set if:</span></div><div style="text-align: left;"><span style="font-family: verdana;"><span> (a) The Squelch has been <u>constantly closed</u> for a predetermined amount of time (menu selectable 30/45/60 seconds) AND the set squelch level is more than 100, 150 or 200 CPS (menu selectable) higher than the currently detected rate. This condition occurs when squelch has been set in a "hot area" and then the instrument transitions to an area with lower background levels. The ASAS mode will normalize the squelch level bringing it closer to the current rate thus removing the large gap which occurs between the current rate and the squelch level (a situation which otherwise will make the squelch less efficient and and will necessitate a manual Auto-Set)</span><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;"><span><span> (b) The Squelch has been constantly open (30,45 or 60 seconds - menu selectable) and the detected rate does not peak higher than 25% to 150% (menu selectable) of the currently set Squelch Level. This condition occurs when Squelch is set in low background radiation area and a transition has been made to a "hot area" where the higher background keeps the squelch constantly open. Again, the Auto-Set will normalize the squelch level.</span><br /></span></span></div><div style="text-align: left;"><span style="font-family: verdana;"><span><span>If a specimen is being located causing the squelch to stay constantly open but also detecting more than pre-set level of spike in the current rate, this will reset the timer in order to prevent an auto-set while trying to pinpoint the location of the source.</span></span></span></div><div style="text-align: left;"><span style="font-family: verdana;">Each of the two timeout timers will reset if a corresponding change of the squelch status occurs.</span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;"><b>Firmware Update v3.8:</b></span></div><div style="text-align: left;"><span style="font-family: verdana;"><b> </b>- added a menu item to set Smart-Squelch timeout - 30, 45 and 60 seconds<br /></span></div><div style="text-align: left;"><span style="font-family: verdana;"><span> - added a menu item to set Smart-Squelch Closed tolerance Level:</span><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;"> <span> </span><span> 4 levels from 100 to 250 CPS in 50 CPS steps</span></span></div><div style="text-align: left;"><div><span style="font-family: verdana;"><span> - added a menu item to set Smart-Squelch Open Reset Level:</span><br /></span></div><div><span style="font-family: verdana;"> rate peak will reset the Timeout timer if exceeds the squelch level by 25%, 37%, 50% and 62%</span></div><div><span style="font-family: verdana;"><span> - added 2 more audio frequency modifiers - x0.5, x1, x1.25 and x1.50</span></span></div><div><span style="font-family: verdana;"><span><span> - added "Charge Completed" battery indicator</span><br /></span></span></div><div><span style="font-family: verdana;"><span><span><span> - various code optimizations, improvements and fixes</span></span></span></span></div><div><span style="font-family: verdana;"><span><span><span><br /></span></span></span></span></div><div><span style="font-family: verdana;"><span><span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7Qoc0vXogAdTP0oIo7olXtak4i6rJW0MbRMGiUECfsCZYwvP_J0_eJ-YAQipfaEbyUU4nbpY9sMaRH_7gnYPRSj_tUZMefT7fj2t_syULH0eeF7lzCwvlP4VlCXnxt2TVoN2c_b5AwtV0ElDJB80cmHtFrzv9Gi_xGyK5bJ1i92iXgQR8cFy477df/s2825/20220503_101619.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1791" data-original-width="2825" height="203" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7Qoc0vXogAdTP0oIo7olXtak4i6rJW0MbRMGiUECfsCZYwvP_J0_eJ-YAQipfaEbyUU4nbpY9sMaRH_7gnYPRSj_tUZMefT7fj2t_syULH0eeF7lzCwvlP4VlCXnxt2TVoN2c_b5AwtV0ElDJB80cmHtFrzv9Gi_xGyK5bJ1i92iXgQR8cFy477df/s320/20220503_101619.jpg" width="320" /></a></div><div style="text-align: center;">The Gamma Dog family.</div><span><br /></span></span></span></span></div></div></div><div><span style="font-family: verdana;"><b>Firmware Update v3.9:</b></span></div><p><span style="font-family: verdana;"></span></p><div><span style="font-family: verdana;"><b> </b>- added "Auto Audio Frequency Multiplier" - activated with the menu system, in this mode the audio frequency multiplication factor will automatically and dynamically be adjusted, based on the difference between set squelch rate and current rate. Change is done in 3 steps - 100-125%, 125-150% and > 150%</span></div></div><div><span style="font-family: verdana;"><span> - added a warning msg if the USB charging cable is plugged in but the power button is not pressed - the instrument will halt the bootup and will wait for a power switch activation. The "stop and wait" point prevents the instrument from startup if nominal voltage is not present on the power rail.</span><br /></span></div><div><span style="font-family: verdana;"><span><span> - reworked the power-saving / sleep mode logic. Now the instrument will start up with normal Time-out delay (duration is set via the config menu system). Gamma Dog will only switch to the short 1 min Sleep Timeout if it detects that a charging cable is plugged in. Disconnecting the cable will cancel the short time Out. If no movement is detected 30 sec to 1 min after the charging cable is plugged in, Gamma Dog will fall asleep. Waking up will restore the normal timeout even if the charging is still going on - this allows for normal operation when charging in the field with an external battery pack. This, more elegant solution is possible by monitoring the status of the on-board charge controller.</span><br /></span></span></div><div><span style="font-family: verdana;"><span><span><span> - added startup shortcut to "Sleep and Charge" Mode in addition to the menu selection</span><br /></span></span></span></div><div><span style="font-family: verdana;"><span><span><span><span> - added a menu item to change the Display Color scheme - Normal (black on white background) or Inverse (white graphics on black background)</span><br /></span></span></span></span></div><div><span style="font-family: verdana;"><span><span><span><span><span> - added second, fast histogram mode - menu-selectable histogram now will display the rate for the last 140 or 45 seconds.</span><br /></span></span></span></span></span></div><div><span style="font-family: verdana;"><span><span><span><span><span><br /></span></span></span></span></span></span></div><div><span style="font-family: verdana;"><span><span><span><span><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="266" src="https://www.youtube.com/embed/q2fT-LdVYN8" width="320" youtube-src-id="q2fT-LdVYN8"></iframe></div><span><div style="text-align: center;">Quick demonstration.</div></span></span></span></span></span></span></div><div><span style="font-family: verdana;"><span><span><span><span><span><br /></span></span></span></span></span></span></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com8tag:blogger.com,1999:blog-5557902467288736826.post-11253674264213096312021-09-20T18:45:00.091-04:002022-08-01T14:27:50.989-04:00Bigger is better or building a larger NaI(Tl)-based scintillating Gamma Spectroscopy detector<p><span style="font-family: verdana;">In the world of scintillators, larger crystals means more sensitivity - when you have a bigger volume of scintillating material, it can capture more photon interactions and will produce more pulses. High-energy photons sometime can pass thru a crystal without interacting with it and more material in the way means higher chance for interaction.</span></p><p><span style="font-family: verdana;">I've been doing some radioactive rockhounding using a scintillator in counting mode and sensitivity is everything when it comes to finding that one specimen a foot or so deep in the ground, under rocks, dirt and mud (which btw act as a pretty good shielding). </span></p><p><span style="font-family: verdana;">A larger scintillating detector was in order and having excellent results with my <a href="http://blog.kotarak.net/2020/11/building-scintillating-gamma.html" target="_blank">first build</a>, I just went right ahead with 63mm crystal and 76mm PMT. This new detector is intended for both, Gamma Spectroscopy and Counting mode when prospecting.</span></p><p style="text-align: center;"><span style="font-family: verdana;"><b>The Photomultiplier Tube</b> </span></p><div class="separator" style="clear: both; text-align: left;"><span style="font-family: verdana;">For PMT I wanted a high quality 3" device and Tom from Irad Inc came thru with a very nice, brand new 8-stage Hamamatsu R6233-05 PMT. This device is intended for use in medical equipment (-05 designation) and came with a factory installed PCB which I removed as it didn't serve the GS purpose - the PCB only contains a few components and not a complete voltage-divider. <b>UPDATE:</b> I have built a half dozen detectors with this type PMT and the results have been absolutely great - it is a really good PMT and became my go-to tube for general spectroscopy and counting.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-lGz8QQown7w/YUkKn981ZcI/AAAAAAAAQkU/39KkteND4r0idYzZX31iHGVSgMpOF1I1wCLcBGAsYHQ/s2048/20210918_204832.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1511" data-original-width="2048" height="236" src="https://1.bp.blogspot.com/-lGz8QQown7w/YUkKn981ZcI/AAAAAAAAQkU/39KkteND4r0idYzZX31iHGVSgMpOF1I1wCLcBGAsYHQ/s320/20210918_204832.jpg" width="320" /></a></div><span style="font-family: verdana;"><a href="https://www.hamamatsu.com/us/en/product/type/R6233/index.html" target="_blank">The Hamamatsu R6233</a>. </span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><span style="text-align: left;">The device is fairly short (only 123mm) and compact for its 3" diameter size. It has 8 dynode stages which are nested tightly in the "neck" portion. A plastic cap on the back insulates the pins. </span></span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The gain (</span><span style="font-family: verdana;">2.7 x10</span><span style="background-color: clear; background-repeat: no-repeat; box-sizing: inherit; color: #333333; font-family: verdana; font-size: 12px; letter-spacing: 0.48px; line-height: 0; margin: 0px; padding: 0px; position: relative; text-align: left; top: -0.5em; vertical-align: baseline;">5</span><span style="font-family: verdana;">) is less than R980 but this is to be expected with 2 dynode stages less - still it is impressive to see that the 10-stage R980's gain is 3.7 x10</span><span style="background-color: clear; background-repeat: no-repeat; box-sizing: inherit; color: #333333; font-family: verdana; font-size: 12px; letter-spacing: 0.48px; line-height: 0; margin: 0px; padding: 0px; position: relative; text-align: left; top: -0.5em; vertical-align: baseline;">5</span></div><div><br /><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-btPPFhjExfs/YUkKoB-rYzI/AAAAAAAAQkY/afTpGZolaCkymZE-UAwFhH43UFJgLE7sACLcBGAsYHQ/s2048/20210918_204729.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1536" data-original-width="2048" height="240" src="https://1.bp.blogspot.com/-btPPFhjExfs/YUkKoB-rYzI/AAAAAAAAQkY/afTpGZolaCkymZE-UAwFhH43UFJgLE7sACLcBGAsYHQ/s320/20210918_204729.jpg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The Bialkali photocathode has an optimal response at 420nm wavelength of the NaI(Tl) crystal. The Photocathode is a tad more sensitive than R980. Effective diameter is 70mm which works perfect for me since the crystal I was going to use is 63mm and larger-than-the-crystal </span><span style="font-family: verdana;">photocathode</span><span style="font-family: verdana;"> </span><span style="font-family: verdana;">is optimal - no photons will be lost leaking to the sides.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-HlDzTlane74/YUkKmTFpwVI/AAAAAAAAQkQ/3EVA6iAIVkIxT5MsvGY5PJmY1ZzDQNpywCLcBGAsYHQ/s1340/20210917_230426.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1011" data-original-width="1340" height="241" src="https://1.bp.blogspot.com/-HlDzTlane74/YUkKmTFpwVI/AAAAAAAAQkQ/3EVA6iAIVkIxT5MsvGY5PJmY1ZzDQNpywCLcBGAsYHQ/s320/20210917_230426.jpg" width="320" /></a></div></div><span style="font-family: verdana;">The factory label - P.H.R. (Peak to Height Ratio) is very good at 7.8% but in reality it is better than the label. The listed PHR is measured with some "standard" for the factory test crystal, with Co-57 (122 keV) source and not the "usual" Cs-137 (662 keV) (hence the lower resolution range). It is more or less worst case.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-reuurh45QNo/YUkKpBO-PgI/AAAAAAAAQkg/4PFP7Jwr5CgUWvsLoN4tVcLOkofMTHXSwCLcBGAsYHQ/s2048/20210918_205947.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1725" height="320" src="https://1.bp.blogspot.com/-reuurh45QNo/YUkKpBO-PgI/AAAAAAAAQkg/4PFP7Jwr5CgUWvsLoN4tVcLOkofMTHXSwCLcBGAsYHQ/s320/20210918_205947.jpg" width="270" /></a></div><span style="font-family: verdana;">The PMT came with a factory-installed PCB which I removed and then the 3 stand-offs were cut off. I marked the Cathode pin (K) with a silver dot and Anode pin (P) with a beige dot, To the left of the Anode pin is the Grid pin and to the right of the Anode is D8. On the left side of the Cathode pin is D1 and then clockwise all the way to D8 in sequence.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The identification of K and P is easy - the Cathode and Grid are the only two pins separated by a single(!) blank space (missing pin)</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-H8lVq4U1_Fo/YabG2-lGLGI/AAAAAAAARL8/Oid0ZDbT-NgOFbdG93K_7-m1GezbLl0DgCLcBGAsYHQ/s2048/20211130_095812.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1919" height="320" src="https://1.bp.blogspot.com/-H8lVq4U1_Fo/YabG2-lGLGI/AAAAAAAARL8/Oid0ZDbT-NgOFbdG93K_7-m1GezbLl0DgCLcBGAsYHQ/s320/20211130_095812.jpg" width="300" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">All VD components - 10 resistors, a cap, lead wires and BNC connector were provided as a kit by iRad Inc.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">A 20M resistor is connected between Cathode and Grid and another 20M between the Grid and D1. Starting with D1, eight 10M resistors are connected between each Dynode (D1 to D8) and between D8 and P.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The resistors are with precision of 1% tolerance and were all checked with an LCR bridge.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Total impedance of the VD is 120M which should be a good choice for battery operated HV supplies which are not as "stiff" as the lab-grade ones.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-aCbtHwtKY_o/YabHLFp9Q4I/AAAAAAAARME/c2jL1KdMXDwcSfwrG4kJCXx7PqscIna7gCLcBGAsYHQ/s2048/20211130_102137.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1854" height="320" src="https://1.bp.blogspot.com/-aCbtHwtKY_o/YabHLFp9Q4I/AAAAAAAARME/c2jL1KdMXDwcSfwrG4kJCXx7PqscIna7gCLcBGAsYHQ/s320/20211130_102137.jpg" width="290" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">10nF / 2kV filter capacitor is installed between D8 and GND (Cathode effectively). The leads of the resistor are kept as short as possible. The A and K leads are made of silver-plated Teflon insulated stranded wires inserted in a second Teflon sleeve.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-zs-3Ba34mPQ/YUtsUMU46LI/AAAAAAAAQpU/J8a-hQXD7YAZb6TKkXUOkbl-Kmh0LK2XwCLcBGAsYHQ/s2528/VD_schematics.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1244" data-original-width="2528" height="157" src="https://1.bp.blogspot.com/-zs-3Ba34mPQ/YUtsUMU46LI/AAAAAAAAQpU/J8a-hQXD7YAZb6TKkXUOkbl-Kmh0LK2XwCLcBGAsYHQ/s320/VD_schematics.jpg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Schematic diagram of the 8-stage Voltage Divider used.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-4yuxyAEuvNU/YUkKqfoLXKI/AAAAAAAAQko/8wSvG6_rvZEXGNcBthIjnGsvZJqKi2VFwCLcBGAsYHQ/s2048/20210918_210111.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1341" height="320" src="https://1.bp.blogspot.com/-4yuxyAEuvNU/YUkKqfoLXKI/AAAAAAAAQko/8wSvG6_rvZEXGNcBthIjnGsvZJqKi2VFwCLcBGAsYHQ/s320/20210918_210111.jpg" width="210" /></a><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The machined plastic cap came from iRad Inc. as well. </span></div></div></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">A BNC connector was installed on the cap and connected with 2 silver-plated Teflon insulated wires. I drilled a small hole on the side of the cap for the grounding lead for the Mu-metal Shield. The hole and wire were sealed on the inside with black RTV sealant after the wire was soldered to the BNC's ground lug.</span></div><div class="separator" style="clear: both; text-align: left;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: left;"><span style="font-family: verdana;">For anyone interested in PMTs and technical details, Hamamatsu published the most comprehensive document I've seen on the subject - <a href="https://www.hamamatsu.com/resources/pdf/etd/PMT_handbook_v3aE.pdf">The PMT Handbook</a>.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><b style="font-family: verdana;">The NaI(Tl) scintillating crystal</b><span style="font-family: verdana;"> </span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-YKgcnpx2xbs/YUyFSe1ODqI/AAAAAAAAQpw/7ZFzHqEJs3Q7gPSoRC8pMRiKSkiIOfmzgCLcBGAsYHQ/s1200/XL-efficiency-1200x800%2B%25281%2529.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="800" data-original-width="1200" height="213" src="https://1.bp.blogspot.com/-YKgcnpx2xbs/YUyFSe1ODqI/AAAAAAAAQpw/7ZFzHqEJs3Q7gPSoRC8pMRiKSkiIOfmzgCLcBGAsYHQ/s320/XL-efficiency-1200x800%2B%25281%2529.png" width="320" /></a></div><span style="font-family: verdana;">Larger crystals have better stopping power resulting in overall better efficiency and this affect mostly the high-energy gamma response.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: left;"><span style="font-family: verdana;">My NaI(Tl) crystal was purchased on eBay and came from Ukraine. The 63mm x 63mm crystals out of Russia or Ukraine (essentially made in Soviet times) seem to be currently very popular on eBay and they tend to produce excellent results.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-_BhAstc5700/YUs6KE4UIII/AAAAAAAAQmY/7vwMin_upyoY3_dxfcRCWCIMsCPsHgYDwCLcBGAsYHQ/s2048/20210917_113455.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="2048" height="320" src="https://1.bp.blogspot.com/-_BhAstc5700/YUs6KE4UIII/AAAAAAAAQmY/7vwMin_upyoY3_dxfcRCWCIMsCPsHgYDwCLcBGAsYHQ/s320/20210917_113455.jpg" width="320" /></span></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Date code is Dec 1987, most likely made in USSR.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-Gt31q2L4s-E/YUs6KRWUbVI/AAAAAAAAQmc/o92PtkT1BJoQLFnkfoyJlKHDEVf133SZQCLcBGAsYHQ/s2048/20210917_113522.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1757" data-original-width="2048" height="275" src="https://1.bp.blogspot.com/-Gt31q2L4s-E/YUs6KRWUbVI/AAAAAAAAQmc/o92PtkT1BJoQLFnkfoyJlKHDEVf133SZQCLcBGAsYHQ/s320/20210917_113522.jpg" width="320" /></span></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The crystal is hermetically sealed in an aluminum canister with an optical glass window and surrounded by reflecting material. The size of the crystal is 63mm x 63mm. The outside diameter of the aluminum can is 71.1mm.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-O-JMPv8IlDg/YUs6KV6TEvI/AAAAAAAAQmg/a8T8b3554jQ7d_96H7DeuaFPOieaAtN4QCLcBGAsYHQ/s2048/20210917_113547.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1669" height="320" src="https://1.bp.blogspot.com/-O-JMPv8IlDg/YUs6KV6TEvI/AAAAAAAAQmg/a8T8b3554jQ7d_96H7DeuaFPOieaAtN4QCLcBGAsYHQ/s320/20210917_113547.jpg" width="261" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The crystal looks pristine!</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">There is a lot of junk sold on eBay - cracked crystals, failed seals, yellowing or cloudy crystals etc.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">One need to very carefully choose what they are buying - some of the garbage crystals I've seen are not even good for counting yet sellers ask hundreds of dollars. If you see any blemishes or imperfections these could be signs of trouble and better to stay away! A failed seal will let moisture in and will destroy the crystal over time - NaI is an extremely hygroscopic substance.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Fortunately, my crystal looks perfect as if it was made yesterday - not 30 years ago. </span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Even when the crystal visually looks great it doesn't mean one will get the best resolution tho!</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><b style="font-family: verdana;">The Size-adapter / Centering Collar</b></div><div class="separator" style="clear: both; text-align: center;"><b style="font-family: verdana;"><br /></b></div><div class="separator" style="clear: both; text-align: left;"><span style="font-family: verdana;">The outer size of the R6233 PMT is listed as 76 +/-0.8 mm and the outer size of the crystal canister is 71.1mm so there is a net difference of ~5mm.</span></div><div class="separator" style="clear: both; text-align: left;"><span style="font-family: verdana;">I wanted to center the crystal to the photocathode and have some reliable way to keep it centered while taping the assembly together so I decided to design a centering collar. The collar will serve as a mechanical protection for the optical interface area.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-tZcDXFVtbv8/YUtDWPpqBNI/AAAAAAAAQms/fJH7FWNevJcAUL95GdgCZ4aPM3-CMi74gCLcBGAsYHQ/s1706/Collar_design.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1123" data-original-width="1706" height="211" src="https://1.bp.blogspot.com/-tZcDXFVtbv8/YUtDWPpqBNI/AAAAAAAAQms/fJH7FWNevJcAUL95GdgCZ4aPM3-CMi74gCLcBGAsYHQ/s320/Collar_design.jpg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The centering / size-adapter was designed with Autodesk TinkerCAD.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-b_SZL7khqtM/YUtEJDNY7AI/AAAAAAAAQm8/GAt88dXBXYYZjZbGw2rVSS_X29qE_8AFgCLcBGAsYHQ/s2048/20210917_112952.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1935" height="320" src="https://1.bp.blogspot.com/-b_SZL7khqtM/YUtEJDNY7AI/AAAAAAAAQm8/GAt88dXBXYYZjZbGw2rVSS_X29qE_8AFgCLcBGAsYHQ/s320/20210917_112952.jpg" width="302" /></span></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The adapter was printed with conventional filament 3D printing technology. </span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The bottom portion for the crystal was originally very tight - there was a small "shrinkage" of the print in this area - about 0.5 mm total so I had to sand it until the adapter can slide freely around the crystal.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-ouzQ5eh9zVw/YUtEJDpZ0BI/AAAAAAAAQm0/8PzrlJyenXIayVNKzmtl2l9rkledc_3YACLcBGAsYHQ/s2661/20210917_112556.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2661" data-original-width="1182" height="320" src="https://1.bp.blogspot.com/-ouzQ5eh9zVw/YUtEJDpZ0BI/AAAAAAAAQm0/8PzrlJyenXIayVNKzmtl2l9rkledc_3YACLcBGAsYHQ/s320/20210917_112556.jpg" width="142" /></span></a></div><span style="font-family: verdana;">"Dry fit" of the three components.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-7NN-xuL_VLY/YUtEJB-apsI/AAAAAAAAQm4/SnBS72rN5m0FUsDutnHtwxqvNoM7DGmowCLcBGAsYHQ/s2048/20210917_112826.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1293" height="320" src="https://1.bp.blogspot.com/-7NN-xuL_VLY/YUtEJB-apsI/AAAAAAAAQm4/SnBS72rN5m0FUsDutnHtwxqvNoM7DGmowCLcBGAsYHQ/s320/20210917_112826.jpg" width="202" /></span></a></div><span style="font-family: verdana;">The purpose of the "fingers" on the adaptor is to be able to tape it or glue it to the PMT and secure it reliably.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-l5Igmz8RFm8/YUtEKdDY5fI/AAAAAAAAQnA/yjVFcYT6QZkPOES7ygClEzF71ejjFTHKgCLcBGAsYHQ/s2048/20210918_091522.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1152" height="320" src="https://1.bp.blogspot.com/-l5Igmz8RFm8/YUtEKdDY5fI/AAAAAAAAQnA/yjVFcYT6QZkPOES7ygClEzF71ejjFTHKgCLcBGAsYHQ/s320/20210918_091522.jpg" width="180" /></a></div><span style="font-family: verdana;">During the assembly, the adapter should fit tightly around the PMT but it should allow the crystal canister to move freely ("float")</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-USyNByLrhak/YUtEKuuoSVI/AAAAAAAAQnE/5YNAvGPBqnA9aRUfj_mi3i3YrRjLEza6ACLcBGAsYHQ/s2048/20210918_210206.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1537" height="320" src="https://1.bp.blogspot.com/-USyNByLrhak/YUtEKuuoSVI/AAAAAAAAQnE/5YNAvGPBqnA9aRUfj_mi3i3YrRjLEza6ACLcBGAsYHQ/s320/20210918_210206.jpg" width="240" /></a></div><span style="font-family: verdana;">The inside area where the transition from one ID size to the other ID takes place is tapered for the glass edge of the PMT. The adapter will center the optical window of the crystal canister exactly to the Photocathode area, while providing both, mechanical stability, shock protection and light-proofing of the interface area.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><b>Optical Assembly</b></span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-uC3zpCxITNM/YUtHQl58rvI/AAAAAAAAQnk/HgrJATbLN8Iw7-vwe384bzLkfHQJNpmwgCLcBGAsYHQ/s2048/20210918_210244.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1335" height="320" src="https://1.bp.blogspot.com/-uC3zpCxITNM/YUtHQl58rvI/AAAAAAAAQnk/HgrJATbLN8Iw7-vwe384bzLkfHQJNpmwgCLcBGAsYHQ/s320/20210918_210244.jpg" width="209" /></span></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">An edge reflector was applied around the front edge of the glass. On this PMT, the photocathode wraps around, to the side for a few millimeters and a reflector in this area will bring back photons otherwise escaping thru the glass edge. I used a couple of turns of white Teflon tape and a layer of pure white PVC tape around the edge and then the whole PMT was light-proofed with the cap, taped securely as well.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-r6jkG-FVa_I/YUtHP5lDGYI/AAAAAAAAQnc/86MCsRF14SkbVXdvRqwgq6lAerCJlgOTgCLcBGAsYHQ/s2048/20210918_095404.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1152" data-original-width="2048" height="180" src="https://1.bp.blogspot.com/-r6jkG-FVa_I/YUtHP5lDGYI/AAAAAAAAQnc/86MCsRF14SkbVXdvRqwgq6lAerCJlgOTgCLcBGAsYHQ/s320/20210918_095404.jpg" width="320" /></span></a></div><div style="text-align: center;"><span style="text-align: left;"><span style="font-family: verdana;">For optical interface medium, I used crystal-clear silicone fluid with viscosity of 100K cSt. It is sold as Differential fluid for high-end RC cars. Consistency is much thicker than honey but flows and spreads nicely and it is absolutely transparent. </span></span></div><div style="text-align: center;"><span style="text-align: left;"><span style="font-family: verdana;">I started by applying an air-bubble-free drop of the fluid in the center of the window and pressing the PMT firmly on top.</span></span></div><div style="text-align: center;"><span style="font-family: verdana;">I worked the PMT with large circular movements while pressing downwards for a couple of minutes, overlapping the edge as much as 1/3 the diameter of the window, until any excess fluid squeezes out from the edge and only a super-thin smooth layer is left, covering the entire glass. This process shouldn't be rushed and excessive force can damage the PMT and/or crystal so extreme caution is in order.</span></div><div style="text-align: center;"><span style="font-family: verdana;">I did notice about 0.2% improvement in FWHM resolution vs. the usual optical silicone grease, probably due to eliminating any possible air pockets / bubbles. </span></div><div style="text-align: center;"><span style="font-family: verdana;">I also experimented with a 60K cSt fluid in the past with excellent results but the thicker 100K fluid has less chance for run-off.</span></div><div style="text-align: center;"><span style="font-family: verdana;">The purpose of the fluid is to eliminate glass-to-air and air-to-glass transitions and reduce the refraction and reflection from the surface of the glass - this makes for an optimal interface between the crystal and the photocathode.</span></div><div style="text-align: center;"><span style="font-family: verdana;">Every time a photon reaches a glass-to-air surface it can be either reflected back or refracted in some direction. The optical fluid substitutes any air gap with almost the same refractive index </span><span style="font-family: verdana;">medium </span><span style="font-family: verdana;">as the glass, thus reducing light scattering and loss.</span></div><div style="text-align: center;"><br /></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-GVfI9yXumCU/YUtHP1JaeXI/AAAAAAAAQng/2v3dLsY_2OsGSA_TqTMRLZ6UG03eoNtgACLcBGAsYHQ/s2048/20210918_101236.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1152" height="320" src="https://1.bp.blogspot.com/-GVfI9yXumCU/YUtHP1JaeXI/AAAAAAAAQng/2v3dLsY_2OsGSA_TqTMRLZ6UG03eoNtgACLcBGAsYHQ/s320/20210918_101236.jpg" width="180" /></span></a></div><span style="font-family: verdana;">I placed the collar around the crystal <u>before</u> I applied the silicone fluid and mated the two glass surfaces. When I was satisfied with the quality of the interface, I simply pulled up the collar while adjusting the PMT's position and pressing it down to the crystal canister.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span><span style="font-family: verdana;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNAJyOl8g1WkTIarKyHh7hMALK9wZqaLGDfOWi8lcbCWzyTJb4Sh-qPdiB0rY-H3hjbTFw4wH8JueByuVEJBoup6iScBbyjCmkYNHuUrzTNN-pTVsjwEt2rkJT02viffJfa5AyjqqqNQJESPbrMOC_SP5Lny9PZ2dRPU17l43jvtD41Kcm4LvArHpR/s4000/20220402_094311.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="4000" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNAJyOl8g1WkTIarKyHh7hMALK9wZqaLGDfOWi8lcbCWzyTJb4Sh-qPdiB0rY-H3hjbTFw4wH8JueByuVEJBoup6iScBbyjCmkYNHuUrzTNN-pTVsjwEt2rkJT02viffJfa5AyjqqqNQJESPbrMOC_SP5Lny9PZ2dRPU17l43jvtD41Kcm4LvArHpR/s320/20220402_094311.jpg" width="149" /></a></div></span></div><div style="text-align: center;"><span style="font-family: verdana;">The entire optical assembly was taped together using electrical tape (3M 88 tape). I started with 8 pieces of tape stretched as tight as possible along the length of the assembly from the crystal's cylinder to the top of the PMT. This "pulls down" the PMT to the crystal with a slight pressure.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-9zurvFJ5bbI/YUtHP0h3iEI/AAAAAAAAQnY/jo53ehFA5Yc_7eiJ38StqZJc6pnwdbfuQCLcBGAsYHQ/s2048/20210918_105700.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1152" height="320" src="https://1.bp.blogspot.com/-9zurvFJ5bbI/YUtHP0h3iEI/AAAAAAAAQnY/jo53ehFA5Yc_7eiJ38StqZJc6pnwdbfuQCLcBGAsYHQ/s320/20210918_105700.jpg" width="180" /></span></a></div><span style="font-family: verdana;"> The assembly was then taped all around starting from bottom to top while still applying pressure between the canister and the PMT.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheR2FzE5SMDCD47Kc-KntYT4XcDupwpMF-Di3-4SxwFBuVzMA_BwocDqmTovMvpMMfOciRJJaxnh4D0MKuX7SHLQ1ZnWnlWksicp8NOp8l7gErQPqQRlOsZzQhSJzLo4CGiUw4bP9zrCR8otpgX2M7JaUqzKGgbtFpUUCD4vWrkGbHZJiKWUQOY9r1/s4000/20220402_100403.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="4000" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheR2FzE5SMDCD47Kc-KntYT4XcDupwpMF-Di3-4SxwFBuVzMA_BwocDqmTovMvpMMfOciRJJaxnh4D0MKuX7SHLQ1ZnWnlWksicp8NOp8l7gErQPqQRlOsZzQhSJzLo4CGiUw4bP9zrCR8otpgX2M7JaUqzKGgbtFpUUCD4vWrkGbHZJiKWUQOY9r1/s320/20220402_100403.jpg" width="149" /></a></div><span style="font-family: verdana;">A rubber foam sleeve around the neck of the PMT tube serves as additional mechanical shock absorber and also increases the diameter of the neck which helps later with the installation of the magnetic shielding. </span><br /><div style="text-align: center;"><br /></div><div style="text-align: center;"><br /></div><div style="text-align: center;"><span style="font-family: verdana;"><b>Mu-Metal Shielding</b></span></div><div style="text-align: center;"><span style="font-family: verdana;"><b><br /></b></span></div><div style="text-align: left;"><span style="font-family: verdana;">Electrons just emitted by the photocathode can easily be deflected by an external magnetic or electric field and miss the grid and the dynode cascade. The effect of magnetic field deflection on the electron's trajectory is worst when the field is parallel to the photocathode. Earth's own magnetic field, while generally weak to affect most electronics devices is still sufficient to cause a deflection for these "freshly emitted" low-energy / low-velocity electrons. Earth's magnetic field is actually strong enough to cause deflections even in the dynode stage so good magnetic shielding must be provided for the PMT. If stronger magnetic fields are expected, than soft iron shield in addition to the Mu-metal is highly recommended.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoh_Kz8ovw_pbc4_at-2m3y5eypmzFwjcb7sboXNJvmVWbyEw6PQB4VTpKqcCrtzF_TJn1y90B8JgkC3nKzuuho7wN21ucVpbyyTiBrw0dc4q0jI6MpDGLOmssdQDPttBW3-DzcB5IrIsQe4I5R9XckqXlzq51dhku7W0xgrscCOSNQAiNnrgO1GTS/s3030/20220402_103111.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1868" data-original-width="3030" height="197" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoh_Kz8ovw_pbc4_at-2m3y5eypmzFwjcb7sboXNJvmVWbyEw6PQB4VTpKqcCrtzF_TJn1y90B8JgkC3nKzuuho7wN21ucVpbyyTiBrw0dc4q0jI6MpDGLOmssdQDPttBW3-DzcB5IrIsQe4I5R9XckqXlzq51dhku7W0xgrscCOSNQAiNnrgO1GTS/s320/20220402_103111.jpg" width="320" /></a></div><span style="font-family: verdana;">The Mu-Metal shielding was constructed in two parts. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The sheets of Mu-Metal with self-adhesive back were sourced from iRad Inc. but they can be obtained from a variety of sources. </span></div><div style="text-align: center;"><span style="font-family: verdana;">Two strips were prepared with numerous cuts / "fingers" to fold around the PMT's profile.</span><br /></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrnYEyVBuExgUi6Rx9kw1As49Jd33TaqLpgjng5teaUzBwUi7Xf9iB9xvrvTIKJlR2g3BWBKUZUvKUqrAPWZc6853CNmtDr8QMOFE2TFqd_O46V2zQByAaiMtnbEmjYueoRs587WPQzMJzWTTvOPcvBE0yEhXzUhhBlhhYBxrJljGg1RGDALuiWule/s4000/20220402_102326.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="4000" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrnYEyVBuExgUi6Rx9kw1As49Jd33TaqLpgjng5teaUzBwUi7Xf9iB9xvrvTIKJlR2g3BWBKUZUvKUqrAPWZc6853CNmtDr8QMOFE2TFqd_O46V2zQByAaiMtnbEmjYueoRs587WPQzMJzWTTvOPcvBE0yEhXzUhhBlhhYBxrJljGg1RGDALuiWule/s320/20220402_102326.jpg" width="149" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The top portion of the Mu shield was wrapped around the neck area of the PMT over the neoprene sleeve in 2 turns and the bottom "fingers" were bent, following the contour of the larger photocathode area.</span></div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg97s14JK7x8GNuwzEo_hmWkrGffANkHs_Qlt94QTLVxL-v4otGBdF0nRqVT8kdJymfo68voGifn5Oo3Rd4jwd3Ov_GSBkNqe1CoZTefSjxOflXrCFt9QRARB2Y0hPPeMPFURc8QkPhSTGdrlxj7EW4nXqtgdDUgpmg_5GU7xisnnabVbcwwkpsg5Ts/s4000/20220402_103538.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="4000" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg97s14JK7x8GNuwzEo_hmWkrGffANkHs_Qlt94QTLVxL-v4otGBdF0nRqVT8kdJymfo68voGifn5Oo3Rd4jwd3Ov_GSBkNqe1CoZTefSjxOflXrCFt9QRARB2Y0hPPeMPFURc8QkPhSTGdrlxj7EW4nXqtgdDUgpmg_5GU7xisnnabVbcwwkpsg5Ts/s320/20220402_103538.jpg" width="149" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">The bottom part of the Mu-shield.</span></div><div style="text-align: center;"><span style="font-family: verdana;">About 1.5 turns of Mu-metal with "fingers" bent, over the top portion of the shield, overlapping and covering all gaps.</span></div><div style="text-align: center;"><span style="font-family: verdana;">This, second part of the shield extends at about 5mm beyond the photocathode and overlaps the top edge of the crystal - it is the more important part of the shielding as it covers the area between the Photocathode and the Grid.</span></div><div style="text-align: center;"><span style="font-family: verdana;">If the detector will be exposed to stronger magnetic fields, more shielding should be added especially in this area.</span></div><span style="font-family: verdana;"><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-_kY8RSTRuQHhrTevOViOTFUTwkTr7fL_uIeNfGyQNO0b07urVlYhSAXFoDxqobLhGXGJyjeTvmuQC-MQax_STctCoZ83AelRQ3x4NU-2enIbETFufKRwRnij0AXqRbxi1d289gnV_2IzT4zVGB3sYddqwsODck6crZ_0caZLwEKCVikFCmovFEt2/s4000/20220402_104751.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="4000" data-original-width="1868" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-_kY8RSTRuQHhrTevOViOTFUTwkTr7fL_uIeNfGyQNO0b07urVlYhSAXFoDxqobLhGXGJyjeTvmuQC-MQax_STctCoZ83AelRQ3x4NU-2enIbETFufKRwRnij0AXqRbxi1d289gnV_2IzT4zVGB3sYddqwsODck6crZ_0caZLwEKCVikFCmovFEt2/s320/20220402_104751.jpg" width="149" /></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;"><div><span style="font-family: verdana;">The grounding lead from the cap is folded and soldered across the Mu-metal collar.</span></div></span></div>The two pieces of metal are grounded together with a few small spot-soldering joints. I was careful to minimize the heating in order to avoid melting the electrical tape or change the magnetic properties of the shield.</span></div><div style="text-align: center;"><span style="font-family: verdana;">When grounded, the Mu-metal shielding doubles as electrostatic shielding - electrons can be deflected by electrostatic fields just as well and draining any charges accumulated on the surface of the tube can be beneficial.<br /><br /></span></div><div style="text-align: center;"><b><span style="font-family: verdana;">Final Assembly</span></b></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-_Uo2HQP8QT4/YUtQracoFnI/AAAAAAAAQoY/4OvRtSMPf5kfPBxHtE0YqBFtyjr7ntPPACLcBGAsYHQ/s2048/20210918_152125.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1152" height="320" src="https://1.bp.blogspot.com/-_Uo2HQP8QT4/YUtQracoFnI/AAAAAAAAQoY/4OvRtSMPf5kfPBxHtE0YqBFtyjr7ntPPACLcBGAsYHQ/s320/20210918_152125.jpg" width="180" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">Another thin foam sleeve and a couple of layers of electrical tape were applied over the Mu-metal shielding in order to make it a tight fit around the PMT.</span></div><div style="text-align: center;"><span style="font-family: verdana;">I also fabricated yet another sleeve out of closed-cell foam ("Neoprene") for the crystal canister. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The foam acts as both - mechanical and thermal insulation - it protects from mechanical shocks and rapid temperature changes of the crystal. It is also a good idea to have this insulation in place for protecting the crystal from a possible thermal shock when the Heat-shrink wrap is applied. There are strict specification how many degrees the temperature should rise over a period of time to avoid stress on the crystal.</span></div><div style="text-align: center;"><span style="font-family: verdana;">Another layer of electrical tape covered the foam sleeves.</span></div><span style="font-family: verdana;"><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-j0ivHNd9SBc/YUtQrXNnehI/AAAAAAAAQoU/L4nJ59zv9BQSWGU--k6ZF4FRfgdVLnfQgCLcBGAsYHQ/s2048/20210918_154808.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1152" height="320" src="https://1.bp.blogspot.com/-j0ivHNd9SBc/YUtQrXNnehI/AAAAAAAAQoU/L4nJ59zv9BQSWGU--k6ZF4FRfgdVLnfQgCLcBGAsYHQ/s320/20210918_154808.jpg" width="180" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">Applying the large size heat-shrink wrap is a bit tricky procedure - it has to be heated evenly from all sides so it shrinks equally around the assembly while being careful not to overheat the crystal - a thermal shock can cause it to crack if heating is happening too rapidly. </span></div><div style="text-align: center;"><span style="font-family: verdana;">I did the entire process with little breaks to allow the temperature to drop and slowly equalize as I was heating the heat-shrink sleeve with my heat gun.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><a href="https://1.bp.blogspot.com/-nsFqMQJQdM8/YUtQsJEx6CI/AAAAAAAAQoc/oDdVYewqrIs44OHkLeE8cEG6wpQo0_K0wCLcBGAsYHQ/s2048/20210918_210416.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1537" height="320" src="https://1.bp.blogspot.com/-nsFqMQJQdM8/YUtQsJEx6CI/AAAAAAAAQoc/oDdVYewqrIs44OHkLeE8cEG6wpQo0_K0wCLcBGAsYHQ/s320/20210918_210416.jpg" width="240" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">The bottom closed-cell foam sleeve was closed off with a thin sheet of the same material, protecting the bottom face of the aluminum canister before the heatshrink was applied</span></div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-LZ5JXKeBQHI/YUtQrPZ03XI/AAAAAAAAQoQ/0c1kK1MLedY1Q5jVN0pIzKRSuPPd6ErigCLcBGAsYHQ/s2048/20210918_154956.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1259" height="320" src="https://1.bp.blogspot.com/-LZ5JXKeBQHI/YUtQrPZ03XI/AAAAAAAAQoQ/0c1kK1MLedY1Q5jVN0pIzKRSuPPd6ErigCLcBGAsYHQ/s320/20210918_154956.jpg" width="197" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">The finished detector came out quite nice and solid. </span></div><div style="text-align: center;"><span style="font-family: verdana;">I still might try to fabricate an outer shell aluminum casing for it, just to make it "bulletproof"</span></div><div style="text-align: center;"><span style="font-family: verdana;">The "Fat Man" codename was changed to Da Gamma Bee II / DGB-2525</span></div><div style="text-align: center;"><br /></div><b style="font-family: verdana;">Conclusion</b><br /><div class="separator" style="clear: both; text-align: center;"><br /></div><div style="text-align: left;"><span style="font-family: verdana;">After waiting sufficient time for the Photocathode to "calm down" from its excited state due to being exposed to daylight during the assembly I started testing the detector first in counting mode just to make sure the VD circuit is all good!</span></div><div style="text-align: left;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><b><span style="font-family: verdana;">(!) A word of caution - PMT should never be powered up when exposed to ambient light - this will absolutely destroy the photocathode in a matter of a second</span>.</b></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-Ctx506TDTFM/YUtaX0EciwI/AAAAAAAAQos/TabUAIEDR80xc_6D9x7oQtxwKAQUOA_DQCLcBGAsYHQ/s2048/20210918_155733.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1152" data-original-width="2048" height="180" src="https://1.bp.blogspot.com/-Ctx506TDTFM/YUtaX0EciwI/AAAAAAAAQos/TabUAIEDR80xc_6D9x7oQtxwKAQUOA_DQCLcBGAsYHQ/s320/20210918_155733.jpg" width="320" /></a></div></div><div style="text-align: center;"><span style="font-family: verdana;">For reference - this is the background count measured with my VD-modified Scionix-Holland 38B57 - 1.5" x 2.25" crystal and R980 PMT (counter is set to x100K range)</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><a href="https://1.bp.blogspot.com/-F5HUvC3YAU0/YUtaX52H4_I/AAAAAAAAQow/rbvn20gjodIDui0ZnBDl_ES_jjB2mZbHACLcBGAsYHQ/s2048/20210918_155641.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1152" data-original-width="2048" height="180" src="https://1.bp.blogspot.com/-F5HUvC3YAU0/YUtaX52H4_I/AAAAAAAAQow/rbvn20gjodIDui0ZnBDl_ES_jjB2mZbHACLcBGAsYHQ/s320/20210918_155641.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">The newly built detector shows more than 2 times increase in the background radiation count. </span><span style="font-family: verdana;">The counter is set to the x100K range so the reading is approx. 20K CPM.</span></div><div style="text-align: center;"><span style="font-family: verdana;">The background measured later with PRA was ~270 CPS or 16.2K CPM but this is normal as PRA rejects malformed pulses, not matching the sampled pulse shape so count will be a bit lower as only pulses good for GS are sorted.</span></div><div style="text-align: center;"><span style="font-family: verdana;">Testing was done at 650V</span></div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-DCzO6iDsmeo/YUtbfKGF5GI/AAAAAAAAQpA/Oswlhp5UqL4_CPr48FRh3-ac5gU1ARk0QCLcBGAsYHQ/s2048/20210920_080635.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1890" data-original-width="2048" height="295" src="https://1.bp.blogspot.com/-DCzO6iDsmeo/YUtbfKGF5GI/AAAAAAAAQpA/Oswlhp5UqL4_CPr48FRh3-ac5gU1ARk0QCLcBGAsYHQ/s320/20210920_080635.jpg" width="320" /></a></div><span style="font-family: verdana;">A quick Gamma Spectroscopy plot of Cs-137 and the results are fantastic - a really nice and clean plot with resolution of 6.53% FWHM at 662keV!</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Such resolution is more or less as good as it gets for these larger NaI(Tl) crystals.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">I used Gamma Spectacular GS-USB-PRO PMT driver set at 650V.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The linearity at this voltage seems very good too - I didn't have to use any Audio Gain factor and all peaks showed up in the right bins indicating that 650V is nearly optimal. In Theremino MCA the Energy equalizer stayed in the same state as before, adjusted after linearity testing and optimization of my other DIY detector. Only the Energy trim had to be adjusted a bit. This is very good sign!</span><br /><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/--RzOrZSvjdM/YUtmBew_qDI/AAAAAAAAQpM/99TaDu-g4S8K3i7J4YU7F6nKH8A7G1YCwCLcBGAsYHQ/s2048/20210922_131718.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1660" data-original-width="2048" height="259" src="https://1.bp.blogspot.com/--RzOrZSvjdM/YUtmBew_qDI/AAAAAAAAQpM/99TaDu-g4S8K3i7J4YU7F6nKH8A7G1YCwCLcBGAsYHQ/s320/20210922_131718.jpg" width="320" /></a></div><span style="font-family: verdana;">"Fat Man" and "Little Boy" in their carry case.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">I built these detectors for the fraction of the cost of a commercial detector, getting the same performance. Interestingly enough the cost of the two is very similar regardless of the size difference.<br /></span><div style="text-align: center;"><br /></div><div style="text-align: center;"><a href="https://1.bp.blogspot.com/-xbU3vEsEY0s/YUtbe7dNMRI/AAAAAAAAQo8/E5xDlpwbQwEbAD1qJUvRkvh8_zmjckKlwCLcBGAsYHQ/s2048/20210919_124219.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1267" data-original-width="2048" height="198" src="https://1.bp.blogspot.com/-xbU3vEsEY0s/YUtbe7dNMRI/AAAAAAAAQo8/E5xDlpwbQwEbAD1qJUvRkvh8_zmjckKlwCLcBGAsYHQ/s320/20210919_124219.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">A new member joins my family of scintillating detectors!</span></div><div style="text-align: center;"><span style="font-family: verdana;"> (L-R) Da Gamma Bee I / DGB-1531 with 40 mm x 80 mm crystal and Hamamatsu R980, Da Gamma Bee II / DGB-2525 with 63 mm x 63 mm crystal and Hamamatsu R6233, modified Scionix-Holland 38B57 with 1.5" x 2.25" crystal and R980 PMT and Gamma Spectacular GS-1525 with 1.5 x 2.5" crystal and Adit PMT.</span></div><div style="text-align: center;"><br /></div></div></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-39434626265218439732021-06-27T10:37:00.012-04:002021-06-27T17:00:25.010-04:00The Sericho Pallasite Meteorite - XRF Analysis<span style="font-family: verdana;">I obtained 2 fragments of the Sericho Pallasite Meteorite, "discovered" in Habaswein, Eastern Kenya in 2016. </span><div><span style="font-family: verdana;">The meteorite has been known to local populations for many years but it wasn't until 2016 when the meteorite was officially classified as such. This was a huge meteorite - so far 2.8t were recovered.</span></div><div><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-LxRujiQgNqs/YNiLqE6aF0I/AAAAAAAAPrc/deIHWDzOLjUgPfhp6ikprLm0JR-0OXZrACLcBGAsYHQ/s2048/meteo4.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1720" data-original-width="2048" src="https://1.bp.blogspot.com/-LxRujiQgNqs/YNiLqE6aF0I/AAAAAAAAPrc/deIHWDzOLjUgPfhp6ikprLm0JR-0OXZrACLcBGAsYHQ/s320/meteo4.jpg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">A highly sculpted complete fragment of the Sericho meteorite. This specimen exhibits the "classic" meteorite look and the fragment is complete, not cut from a larger piece.</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-OdFKjfxD5jU/YNiMsvMG5XI/AAAAAAAAPrs/SfREPQsoqU0O6_ES0jLdcPaZ7lqd80f-ACLcBGAsYHQ/s2048/meteo1.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1743" data-original-width="2048" src="https://1.bp.blogspot.com/-OdFKjfxD5jU/YNiMsvMG5XI/AAAAAAAAPrs/SfREPQsoqU0O6_ES0jLdcPaZ7lqd80f-ACLcBGAsYHQ/s320/meteo1.jpg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The second specimen is an end-cut piece from a larger fragment. It exhibits the typical "fusion crust" from the entry in Earth's atmosphere. </span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-B4-mjapX0ro/YNiLm3st_xI/AAAAAAAAPrY/iOQ-ixonZXgmm4zwY-foQURzO3Xvatn2QCLcBGAsYHQ/s2048/meteo3.JPG" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1365" data-original-width="2048" src="https://1.bp.blogspot.com/-B4-mjapX0ro/YNiLm3st_xI/AAAAAAAAPrY/iOQ-ixonZXgmm4zwY-foQURzO3Xvatn2QCLcBGAsYHQ/s320/meteo3.JPG" width="320" /></a></div><span style="font-family: verdana;">The back side of the second piece with straight polished cut reveals the pallasite nature of the meteorite and a structure of olivine crystals.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-lBuFNDTN-g0/YNiSXaCw9sI/AAAAAAAAPsA/-l3JWgHZ6poQzvKwL2-k3SK0aLzlSfxDQCLcBGAsYHQ/s2048/meteo5_XRF.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1952" height="320" src="https://1.bp.blogspot.com/-lBuFNDTN-g0/YNiSXaCw9sI/AAAAAAAAPsA/-l3JWgHZ6poQzvKwL2-k3SK0aLzlSfxDQCLcBGAsYHQ/s320/meteo5_XRF.jpg" /></a></div><span style="font-family: verdana;">The XRF Analysis setup - the polished cut of the meteorite is exposed to the 59.54 keV X-Ray source and the X-Ray detector. I placed the source a bit further away decreasing the intensity in order to eliminate parasitic peaks coming from Np, Au and Ag in the source itself. The weaker beam resulted in a long acquisition time - nearly 6 hours but produced a fairly clean spectrum.</span><br /></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-OVH0wmSOiMk/YNiOOZHGT5I/AAAAAAAAPr4/AyCguurp8tkstuiX5jhuUdUAY6-zGpaRACLcBGAsYHQ/s2549/meteorite_Sericho.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1234" data-original-width="2549" src="https://1.bp.blogspot.com/-OVH0wmSOiMk/YNiOOZHGT5I/AAAAAAAAPr4/AyCguurp8tkstuiX5jhuUdUAY6-zGpaRACLcBGAsYHQ/s320/meteorite_Sericho.jpg" width="320" /></a></div><span style="font-family: verdana;">XRF analysis plot.</span></div><div style="text-align: center;"><span style="font-family: verdana;">As it turns out from an XRF point of view, much like most other meteorites, Sericho is typical and quite boring - no exotic metals are present - just Iron, Nickel and traces of Cobalt and Chromium.</span></div><div style="text-align: center;"><span style="font-family: verdana;">The plot prominently features the Kα1 and Kβ1 peaks of Iron and smaller peaks of Nickel. Cobalt is in very low concentration (0.8%) and masked but if one looks for it, it can be seen in the irregular shape of the base (on the right side) of the Ni Kα1 photopeak. The Ni Kα1 at 7.48 keV is too close to the 7.65 keV of the Kβ1 of Cobalt just at the edge of the detector resolution. The 6.93 keV Kα1 line of the Co is dominated by the Kβ1 Fe at 7.06 keV and can not be differentiated. Chromium can not be detected at all with my setup due to the trace amounts (0.03%)</span></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com2tag:blogger.com,1999:blog-5557902467288736826.post-14486290912842666972021-06-27T10:22:00.006-04:002023-03-13T12:59:24.941-04:00My XRF Setup - Part 3 - Exciter<p><span style="font-family: verdana;">The exciter is the second main component of an XRF setup - this is the source of the primary X-Rays.</span></p><p><span style="font-family: verdana;">Two type of Exciters are generally used - X-Ray tube or Radioactive Isotope.</span></p><p><span style="font-family: verdana;"><b>X-Ray tubes</b> </span></p><p><span style="font-family: verdana;">Pros:</span></p><p><span style="font-family: verdana;">- provide high-intensity beam</span></p><p><span style="font-family: verdana;">- low limit of element detection</span></p><p><span style="font-family: verdana;">- easy on/off capabilities </span></p><p><span style="font-family: verdana;">- fast integration times</span></p><p><span style="font-family: verdana;">- fairly clean and uniform spectrum</span></p><p><span style="font-family: verdana;">- very small spot of irradiation / sampling </span></p><p><span style="font-family: verdana;">Cons:</span></p><p><span style="font-family: verdana;"> - big, heavy, very delicate</span></p><p><span style="font-family: verdana;">- require additional cooling</span></p><p><span style="font-family: verdana;">- large, hazardous HV power supplies</span></p><p><span style="font-family: verdana;">- need for safety interlock system</span></p><p><span style="font-family: verdana;">- heavy beam collimators</span></p><p><span style="font-family: verdana;">- substantial shielding is required</span></p><p><span style="font-family: verdana;">- Not as portable</span></p><p><span style="font-family: verdana;"><b>Radioactive Isotope source</b> </span></p><p><span style="font-family: verdana;">Pros: </span></p><p><span style="font-family: verdana;">- smaller, lighter and simple to use</span></p><p><span style="font-family: verdana;">- 100% reliable</span></p><p><span style="font-family: verdana;">- very portable for field use</span></p><p><span style="font-family: verdana;">Cons:</span></p><p><span style="font-family: verdana;">- low intensity beam requires long acquisition times</span></p><p><span style="font-family: verdana;">- shielding is required as well a shutter-type on/off system</span></p><p><span style="font-family: verdana;">- highly regulated</span></p><p><span style="font-family: verdana;">- danger of contamination if source is damaged</span></p><p><span style="font-family: verdana;">- spectrum is not as clean and can contain various peaks</span></p><p><span style="font-family: verdana;"> The holder of the exciter was designed with TinkerCAD and 3D printed</span></p><p><br /></p><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-ujasaVVybc4/YNiI-C0dw4I/AAAAAAAAPq0/BtJ8-YCf9iUHshTk8uxTXel23VOFrzJrwCLcBGAsYHQ/s2048/20210328_213328.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1152" data-original-width="2048" src="https://1.bp.blogspot.com/-ujasaVVybc4/YNiI-C0dw4I/AAAAAAAAPq0/BtJ8-YCf9iUHshTk8uxTXel23VOFrzJrwCLcBGAsYHQ/s320/20210328_213328.jpg" width="320" /></a></div></div><br /><br /><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-zGqy6K2APHo/YNiJg0drnQI/AAAAAAAAPrE/HL0LncrACEcVbqZdARtI1CCMhcdKQAxkACLcBGAsYHQ/s2048/20210401_193825.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1990" height="320" src="https://1.bp.blogspot.com/-zGqy6K2APHo/YNiJg0drnQI/AAAAAAAAPrE/HL0LncrACEcVbqZdARtI1CCMhcdKQAxkACLcBGAsYHQ/s320/20210401_193825.jpg" /></a></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-whQhciQ9kFc/YNiJgwPi4gI/AAAAAAAAPrI/4oDaQ7OogD4vNH2o4ydq8pM1ez7MDSaXgCLcBGAsYHQ/s2048/20210401_193648.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1964" height="320" src="https://1.bp.blogspot.com/-whQhciQ9kFc/YNiJgwPi4gI/AAAAAAAAPrI/4oDaQ7OogD4vNH2o4ydq8pM1ez7MDSaXgCLcBGAsYHQ/s320/20210401_193648.jpg" /></a></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-B_YrOUo3iGM/YNiJg07XMbI/AAAAAAAAPrA/PmRNX0PAY6smrbzMFNK7HJUj7dlu3kuiACLcBGAsYHQ/s2048/20210401_193521.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1440" data-original-width="2048" src="https://1.bp.blogspot.com/-B_YrOUo3iGM/YNiJg07XMbI/AAAAAAAAPrA/PmRNX0PAY6smrbzMFNK7HJUj7dlu3kuiACLcBGAsYHQ/s320/20210401_193521.jpg" width="320" /></a></div><span style="font-family: verdana;"><div><span style="font-family: verdana;">While this method works and it is a convenient way to use a number of small sources, the main problem is that they need to be placed at some distance from the Object Under Test which decreases the flux and irradiates a larger area of the specimen.</span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">I made also a small, single, directed source with a Lead collimator which works very well and I can place it much closer</span></div><br /></span><div><span style="font-family: verdana;"><b>Update:</b> X-Ray tube is added as yet another option to do XRF excitation. See <a href="http://blog.kotarak.net/2023/01/xrf-exciter-source-using-moxtek.html">THIS post</a>.</span></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com1tag:blogger.com,1999:blog-5557902467288736826.post-87471454774458535032021-04-30T19:55:00.033-04:002021-07-01T01:55:05.076-04:00My XRF Setup - Part 2 / X-Ray Spectrometer<p><span style="font-family: verdana;"> Amptek (<a href="https://www.amptek.com/">Amptek</a>) is one of the leading companies for Space instrumentation, experimental and research XRF equipment.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-DYhD-IFZ-bU/YIyU6fspyPI/AAAAAAAAPNs/9whV6GMvpQAjecA6GuIcs7zGiAxnwNGzQCLcBGAsYHQ/s1024/Amptek_XRF2.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="684" data-original-width="1024" src="https://1.bp.blogspot.com/-DYhD-IFZ-bU/YIyU6fspyPI/AAAAAAAAPNs/9whV6GMvpQAjecA6GuIcs7zGiAxnwNGzQCLcBGAsYHQ/s320/Amptek_XRF2.jpg" width="320" /></span></a></div><p><span style="font-family: verdana;">They have a fantastic line of products called X-123 Spectrometer - (1) detector element and preamplifier, (2) Digital Pulse Processor and MCA and (3) Power supply. It is all-in-one device which only requires an external power and connection to a computer. The PC software by Amptek called DppMCA is used to configure, control the X-123 operation and receive & visualize the accumulated spectrum.</span></p><p><span style="font-family: verdana;">Once the acquisition process is started, X-123 doesn't even need the computer connection until it is time to receive, save and display the data, integrated by the internal to X-123 multi-channel analyzer (MCA) located on the DP5 module. </span></p><p><span style="font-family: verdana;">X-123 Spectrometers are offered with a variety of detectors - Si-PIN, SDD, Fast SDD or CdTe and can employ different length extenders between the case and the detector element. Fast SDD is their top-of-the-line model, while Si-PIN is more of a general use detector. CdTe detectors are great for the higher energy region - up to 150 keV at the expense of resolution and internal noise.</span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-aQsdM--NWtA/YI08YPyfJ5I/AAAAAAAAPOU/iyFhvhbGiDgehBkvvmyW-soEEacMDp5bACLcBGAsYHQ/s2048/20210407_135610.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1152" data-original-width="2048" src="https://1.bp.blogspot.com/-aQsdM--NWtA/YI08YPyfJ5I/AAAAAAAAPOU/iyFhvhbGiDgehBkvvmyW-soEEacMDp5bACLcBGAsYHQ/s320/20210407_135610.jpg" width="320" /></a></div><p></p><span style="font-family: verdana;">I got my detector from George Dowel (GEO Electronics) as Geo-123. Internally, the unit is identical to the commercial Amptek Si-PIN X-123 unit - George uses the OEM modules and installs them in a custom-machined enclosure. The enclosure is a bit larger than the commercial Amptek version but this is an advantage - the aluminum alloy enclosure actually acts as a giant heatsink for the heat pumped by the TEC module, located inside the detector element and larger surface area results in better heat dissipation.</span><div><span style="font-family: verdana;">If there is one thing I wish for, is to have at least 1" or more extension between the detector and the main enclosure - this could help a lot with detector placement in relation to the sample and the exciter.<br /></span><div><span style="font-family: verdana;"><br /></span></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-MeRB0nBC-jo/YIylCTu1i3I/AAAAAAAAPN8/lcVjbjDQ8JAJmcRR713aM_8uJlW2V4SeACLcBGAsYHQ/s2048/20210401_194056.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1911" height="320" src="https://1.bp.blogspot.com/-MeRB0nBC-jo/YIylCTu1i3I/AAAAAAAAPN8/lcVjbjDQ8JAJmcRR713aM_8uJlW2V4SeACLcBGAsYHQ/s320/20210401_194056.jpg" /></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">The "business end" of the unit - the 25 mm<span style="font-size: x-small;">2</span>
/ 500 μm</span> <span style="font-family: verdana;">Si-PIN X-Ray detector element </span><span style="font-family: verdana;">(model FSJ32MD-G3SP) with</span><span style="font-family: verdana;"> a thin, very fragile 1 mil Beryllium window.</span></div><div style="text-align: center;"><span style="font-family: verdana;"> </span></div></span></div><div style="text-align: center;"><span style="font-family: verdana;"><b>(!) This window must never be touched by hand or come in contact with any object - such thing could turn into a very costly mistake!</b></span></div><div style="text-align: center;"><span style="font-family: verdana;"><b><br /></b></span></div><div style="text-align: center;"><span style="font-family: verdana;">Out-of-the-box there is a red polyethylene protective cap installed. There is actually very little reason for the red protective cap to be removed and the detector works with the cap on. I would expect to see some attenuation in the very low end of the range (0 to 2 keV) when the cap is on but even with this cap, Calcium K-lines are actually detectable.</span></div><div style="text-align: center;"><span style="font-family: verdana;">(</span><span style="font-family: verdana;">George supplies a spare modified cap with a built-in thin Kapton window</span><span style="font-family: verdana;"> )</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;">Energy resolution is 190 - 225 eV FWHM @ 5.9 keV, peaking time 25.6 </span><span style="font-family: verdana;">μs and Peak-to-Background ratio: 2000/1 (typical).</span></div><div><span style="font-family: verdana;"><br /></span></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-ZQJPyf501u0/YIzu_yLwJ_I/AAAAAAAAPOM/dX-0EcUcSC4odAszcN-NYRHwCYiJhvKFQCLcBGAsYHQ/s1908/Si-PIN_efficiency.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1184" data-original-width="1908" src="https://1.bp.blogspot.com/-ZQJPyf501u0/YIzu_yLwJ_I/AAAAAAAAPOM/dX-0EcUcSC4odAszcN-NYRHwCYiJhvKFQCLcBGAsYHQ/s320/Si-PIN_efficiency.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">Plot showing the efficiency as a function of energy for Si-PIN detector. </div><div style="text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-7qQH5_D1xoQ/YN1U589V3bI/AAAAAAAAPuA/6VENPGJQCjUVWUkYHCf3Pg40CM3JPsHnACLcBGAsYHQ/s566/SiPIN_eff.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="409" data-original-width="566" src="https://1.bp.blogspot.com/-7qQH5_D1xoQ/YN1U589V3bI/AAAAAAAAPuA/6VENPGJQCjUVWUkYHCf3Pg40CM3JPsHnACLcBGAsYHQ/s320/SiPIN_eff.png" width="320" /></a></div></span></div><div><div style="text-align: center;"><span style="font-family: verdana;">The optimal energy range for a SiPIN detector is 1 to 10 keV. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The range of 10 keV to 25 keV exhibits a drop in efficiency to ~25%. </span></div><div style="text-align: center;"><span style="font-family: verdana;">Below 1 keV the loses from X-Rays traveling thru the air are significant - only 1cm of air will stop 90% of the X-Rays.</span></div><span style="font-family: verdana;"><div style="text-align: center;">Above 25 keV the detector is still useable up to around 60 keV with a rapidly decreasing efficiency.</div></span></div><div><span style="font-family: verdana;"><br /></span></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-eXqc1Vg5fG0/YIyvsQx-pGI/AAAAAAAAPOE/mb5V-qdo8xoXatExA-YyPCREZ8N8JA3DgCLcBGAsYHQ/s2048/20210407_135529.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1152" data-original-width="2048" src="https://1.bp.blogspot.com/-eXqc1Vg5fG0/YIyvsQx-pGI/AAAAAAAAPOE/mb5V-qdo8xoXatExA-YyPCREZ8N8JA3DgCLcBGAsYHQ/s320/20210407_135529.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">The X-123 Spectrometer supports USB 2.0 (mini-USB Connector), RS-232 (2.5mm jack) and Ethernet (RJ45) computer connections. </div><div style="text-align: center;"><br /></div></span></div><div><span style="font-family: verdana;">USB works just fine and it is very fast so I never had the motivation to try any of the other interfaces. The Ethernet connectivity might require a future software release for full implementation, according to one Amptek document, but the orange data light on the port is a useful indicator - it is lit solid if the data acquisition is stopped and it is blinking when the MCA is running and storing data.</span></div><div><span style="font-family: verdana;">Other connectors on the back are the proprietary jack for the External Power supply and there is also a well documented auxiliary connector for gated counts and other functions.</span></div><div><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-ZvX1pSwc1U4/YKPuzZYSJMI/AAAAAAAAPXw/PP2VnFKtUDM2-swkELVl0DW5fxOa4KyMwCLcBGAsYHQ/s400/Amptek%2Bdp5_3.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="252" data-original-width="400" src="https://1.bp.blogspot.com/-ZvX1pSwc1U4/YKPuzZYSJMI/AAAAAAAAPXw/PP2VnFKtUDM2-swkELVl0DW5fxOa4KyMwCLcBGAsYHQ/s320/Amptek%2Bdp5_3.jpg" width="320" /></a></div><span style="font-family: verdana;">The "sandwich" of DP5 Digital Pulse Processor (top board) and PC5 power supply module on the bottom. A ribbon cable connects DP5 to the PA230 Pre-amplifier board.</span><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">External power is supplied with a very small, proprietary connector (George provides a spare connector in the kit). </span></div><div><span style="font-family: verdana;">The power adapter is regulated and rated for 5V / 2.5A. </span></div><div><span style="font-family: verdana;">The current rating is very important - while the unit only needs 500-700 mA during normal operation, there is a short, high-current transient of around 2A during the boot up sequence and any current limiting bellow 2A could damage the internal power supply PC5 module.</span></div><div><span style="font-family: verdana;">All of the power conditioning and the generation of various voltages is done internally by the PC5 power supply module.<br /></span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">The Amptek software - DppMCA is quite good and I really like it! It is available on the AmpTek web site for free. The software is fairly easy to use and provides extensive toolset for data acquisition and analysis. The peak identification feature using energy reference libraries is very useful. The UI is logical and easy to use and ability to customize the color schemes.</span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">There are a few features I wish it had but overall it does its job very well and it is well integrated with the hardware DP5 Pulse Processor</span><span style="font-family: verdana;">.</span></div><div><span style="font-family: verdana;">Speaking of the DP5 module, the built-in hardware MCA in X-123 is quite impressive - 256 to 8192 channels (I normally use it in 4096 channels configuration) and 24 bits per channel (16.7 million counts). Acquisition time is selectable from 10 ms to 466 days. </span></div><div><span style="font-family: verdana;">The MCA can be set to work in two modes - NORMAL and DELTA. In Delta mode it shows the spectrum, refreshed every second with pulses integrated over the past 1 second.</span></div><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">Combination of coarse and fine amplifier gain yields an overall Gain, continuously adjustable from x0.84 to x127.5 - the amount of preamp Gain determines the spread of the spectrum over a specified number of channels in the MCA.</span></div><div><span style="font-family: verdana;">For example, when using 4096 Channels, a Gain of x18.5 allows coverage of 0 to 62 keV range.</span></div><div><span style="font-family: verdana;"><br /></span></div><div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-KdYM6KEvdYk/YKJ-22hrWhI/AAAAAAAAPW0/MABEGlK3egYzY6MqgnMHLdkxjLINVO9-ACLcBGAsYHQ/s2048/Cu_calibration_XRF.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1065" data-original-width="2048" src="https://1.bp.blogspot.com/-KdYM6KEvdYk/YKJ-22hrWhI/AAAAAAAAPW0/MABEGlK3egYzY6MqgnMHLdkxjLINVO9-ACLcBGAsYHQ/s320/Cu_calibration_XRF.jpg" width="320" /></a></div><span style="font-family: verdana;">The Si-PIN detector response is quite linear and 2 point calibration is all that is needed for most applications.</span></div><div style="text-align: center;"><span style="font-family: verdana;">I use pure, 99.9% Copper (Cu) foil - the Kα1 line at 8.05 keV and the Am-241 X-rays at 59.54 keV at the high end of the spectrum are sufficient for channel/energy calibration but more intermediate points can easily be added if necessary using different pure metals.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-U1tyl9NRSZo/YKZ2FWN_6NI/AAAAAAAAPYI/thX65363iy0YQixco3I93vciQzE6FB8sQCLcBGAsYHQ/s500/Gd_disk.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="479" data-original-width="500" src="https://1.bp.blogspot.com/-U1tyl9NRSZo/YKZ2FWN_6NI/AAAAAAAAPYI/thX65363iy0YQixco3I93vciQzE6FB8sQCLcBGAsYHQ/s320/Gd_disk.jpg" width="320" /></a></div><span style="font-family: verdana; text-align: left;">Gadolinium (Gd) is a Rare-Earth Element which is very interesting to XRF with its many peaks and also can be used as a calibration aid since both L and K-lines show up nicely at the low and high energy range of the detector.</span><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-XOinvxl70zA/YKaXgl9aT4I/AAAAAAAAPYU/9H0O-liMmAozIH6X84_mTkaSg7Vvdj9WwCLcBGAsYHQ/s2530/Gd_scan_XRF1.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1243" data-original-width="2530" src="https://1.bp.blogspot.com/-XOinvxl70zA/YKaXgl9aT4I/AAAAAAAAPYU/9H0O-liMmAozIH6X84_mTkaSg7Vvdj9WwCLcBGAsYHQ/s320/Gd_scan_XRF1.jpg" width="320" /></a></div><span style="font-family: verdana;"><div style="text-align: center;"><span style="font-family: verdana;">XRF of a 99.9% pure 1" disk of Gadolinium (Gd).</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: left;"><span style="font-family: verdana;">Most of the Gd peaks can be easily identified - Kα1, </span>Kα2, Kβ1, Kβ2, Lα1/Lα2, Lβ1, Lβ2 and even L<span><span style="font-family: verdana;">γ1, L</span></span><span>γ2 and </span>Ll are visible in this plot. Obviously, Lα1 and Lα2 can not be separated - they are only 30 eV apart - way too close for the 190-225 eV resolution of the Si-PIN detector.</div><div style="text-align: left;"><br /></div><div style="text-align: left;">The very low count "hash" above the group of Gd L-lines is caused by Np-237 L-lines coming from the native spectrum of the exciter - 25 μCi of Am-241. Am-241 decays to Np-237 and the L-lines of the Neptunium are Rayleigh scattering and somewhat visible in the spectrum. </div><div style="text-align: left;">The Exciter's X-Ray beam is collimated and reduced down to about 3mm spot for a precise sampling so the overall count rate is low as expected but the spectrum is nice and fairly clean. Longer integration times are to be expected with this type of exciter and I use a different exciter with a broader beam for general purpose.</div></span></div></div></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com1tag:blogger.com,1999:blog-5557902467288736826.post-74504655567313090992021-04-29T21:27:00.033-04:002023-03-12T22:12:57.412-04:00My XRF Setup - Part 1 / How it all works?<p style="text-align: center;"><span style="font-family: verdana;"><span style="color: #0b5394; font-size: medium;"><b> What is XRF?</b></span><span style="color: #2b00fe;"> </span></span></p><p><span style="font-family: verdana;">XRF stands for "X-Ray Fluorescence" and there are two main types: Energy Dispersive XRF and Wavelength Dispersive XRF. </span></p><p><span style="font-family: verdana;">I'll focus on the Energy Dispersive, Direct Excitation (2D) Method as this is what I use. </span></p><p><span style="font-family: verdana;">EDXRF is a Non-Destructive method for material analysis, used to determine the Elemental composition of a material or a chemical compound. It is an extremely useful tool to analyze raw materials, minerals, alloys, etc.</span></p><p><span style="font-family: verdana;">The Physics behind XRF is absolutely fascinating and at the same time relatively simple to understand.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-utFmvU_gLnw/YItZMAYU5kI/AAAAAAAAPM0/RG2jBXx4_w0PgV26qstV5erSGmazusdaACLcBGAsYHQ/s680/XRF-primary-x-ray-radiation.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="404" data-original-width="680" src="https://1.bp.blogspot.com/-utFmvU_gLnw/YItZMAYU5kI/AAAAAAAAPM0/RG2jBXx4_w0PgV26qstV5erSGmazusdaACLcBGAsYHQ/s320/XRF-primary-x-ray-radiation.jpg" width="320" /></span></a></div><p><span style="font-family: verdana;">The description of the whole process can be boiled down to this: exposing a test sample to a beam of X-Ray radiation and detecting the energy of the secondary / characteristic X-Rays emitted by the atoms in the sample and then building a histogram of the energy spectrum in order to identify specific secondary X-Ray peaks.</span></p><p><span style="font-family: verdana;">When a material is irradiated by short-wavelength ionizing radiation like X-Rays or low-energy Gamma Rays, the electrons from the innermost electron shells, the ones closest to the nucleus (K, L, M shells) will become excited and are expelled from the atom. This causes a vacancy in that lower electron shell and it is immediately filled with an electron from a higher-energy shell.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-61aMBhlD8Xk/YItZeTZveHI/AAAAAAAAPM8/M6CM4WdyXYIs0DjuPT2-o9PKN6rXf0AlwCLcBGAsYHQ/s680/XRF-Radiation1.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="646" data-original-width="680" src="https://1.bp.blogspot.com/-61aMBhlD8Xk/YItZeTZveHI/AAAAAAAAPM8/M6CM4WdyXYIs0DjuPT2-o9PKN6rXf0AlwCLcBGAsYHQ/s320/XRF-Radiation1.jpg" width="320" /></span></a></div><p><span style="font-family: verdana;">For example, if the electron is ejected from the K-shell, this vacancy will be filled by an electron from the L or M shells. When the electron makes the jump from a higher-energy shell to a lower-energy shell in order to fill such vacancy, it must give off the excess energy and does it so by emitting a photon with energy equivalent to the difference. This secondary photon is again, an X-Ray photon but with a very specific energy to the particular element due to the unique binding energy between the nucleus of each element (with its protons) and the surrounding electron shells.</span><span style="font-family: verdana;"> </span></p><p><span style="font-family: verdana;">This, secondary emitted photon is called a <i>Characteristic X-Ray</i>. By detecting the energy of these characteristic X-Rays we can determine which Element from the Periodic Table the examined atom belongs to. </span></p><p><span style="font-family: verdana;">There is a number of such characteristic X-Rays emitted, based on which shell, the electron comes from to fill the vacancy of the electron expelled by the primary X-Rays - if the vacancy is in the innermost shell (K-shell) and it is filled from the L-shell it is called Kα energy, if it is filled by the M shell is Kβ</span><span style="font-family: verdana;"> energy and so on. Vacancies in the L-shell are filled from the M-shell and are called Lα</span><span style="font-family: verdana;"> and when filled from N-shell - Lβ</span><span style="font-family: verdana;">. </span></p><p><span style="font-family: verdana;">These characteristic X-rays energy are published in lookup <a href="http://www.kotarak.net/XRF-AmpTek_Table.pdf">XRF tables</a>.</span></p><p><span style="font-family: verdana;">Overlaps between </span><span style="font-family: verdana;">Kα/</span><span style="font-family: verdana;">Kβ and</span><span style="font-family: verdana;"> </span><span style="font-family: verdana;">Lα/</span><span style="font-family: verdana;">Lβ </span><span style="font-family: verdana;">energies for some elements exist so identifying an element often relies on identifying multiple energy peaks in the spectrum, coming from different transition lines.</span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-WFrrqB5aZd4/YIwWCZJtmaI/AAAAAAAAPNc/Crs1Ytewj141KqCUKiMujWbNVIitNN5XgCLcBGAsYHQ/s2048/cobalt_analysis.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1349" data-original-width="2048" src="https://1.bp.blogspot.com/-WFrrqB5aZd4/YIwWCZJtmaI/AAAAAAAAPNc/Crs1Ytewj141KqCUKiMujWbNVIitNN5XgCLcBGAsYHQ/s320/cobalt_analysis.jpg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">This is a typical XRF histogram as produced by the MCA software. I used a small sample of pure (99.98%) Cobalt metal for this test. The two blue peaks on the very left are the Kα and </span><span style="font-family: verdana;">Kβ</span><span style="font-family: verdana;"> lines of Cobalt. </span></div><p></p><p style="text-align: center;"><span style="font-family: verdana;">The other peaks in the spectrum above are just parasitic peaks coming from the X-ray exciter or the environment - for example the tall green peak on the right of the Cobalt peaks is the Bromine </span><span style="font-family: verdana;">Kα</span><span style="font-family: verdana; font-size: small; text-align: left;">1</span><span style="font-family: verdana;">-line @ 11.92 keV immediately followed by the Br </span><span style="font-family: verdana;">Kβ</span><span style="font-family: verdana; font-size: small; text-align: left;">1</span><span style="font-family: verdana;">-line @ 13.29 keV, all </span><span style="font-family: verdana;">coming from the plastic clamp I used to hold the small Cobalt metal sample in front of the detector - the Bromine was likely used in manufacturing of the dye or filler of the plastic and even though the clamp was just partially exposed to the detector the Bromine (Br) lines were still detected.</span></p><p style="text-align: center;"><span style="color: #0b5394; font-family: verdana; font-size: medium;"><b>What do I need for XRF?</b></span></p><p><span style="font-family: verdana;">At a very basic level - three things : X-Ray Source, X-Ray detector and a computer.</span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-kFxYuUpZwLo/YIySD5vDrTI/AAAAAAAAPNk/v_OJghNz5ngtUBU7brToLWrcSx-YLUPlACLcBGAsYHQ/s2038/Amptek_XRF.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1299" data-original-width="2038" src="https://1.bp.blogspot.com/-kFxYuUpZwLo/YIySD5vDrTI/AAAAAAAAPNk/v_OJghNz5ngtUBU7brToLWrcSx-YLUPlACLcBGAsYHQ/s320/Amptek_XRF.jpg" width="320" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">The Amptek XRF Kit - Mini-X X-Ray tube and the all-in-one X-123 detector.</span></div><p></p><p><span style="font-family: verdana;"><b>X-Ray source:</b> obviously the best source is an X-Ray tube in the 40-60 kV range but these require forced cooling, HV power supply, lots of shielding and a collimator. Such setups are large and very expensive. There are small and portable tubes but they usually have an even higher price tag.</span></p><p><span style="font-family: verdana;">Alternatively a radioactive isotope emitting low-energy gammas / X-Rays can be used as an exciter - Cd-109, Fe-55 or Am-241 just to name a few. The intensity is usually lower than the beam from an X-Ray tube, even when mCi amounts of activity are used so counting times are longer, but it is a very portable and uncomplicated method to produce the primary X-Rays. It is important that the energy of the exciting X-Ray beam is higher than the characteristic energy to be detected.</span></p><p><span style="font-family: verdana;">Needless the say, regardless whether the exciter is an X-Ray tube or a Radioactive Isotope, caution must be exercised at all times dealing with ionizing radiation. </span></p><p><span style="font-family: verdana;"><b>X-Ray Detector</b>: the X-Ray detector must have very high-resolution (typically 122-200 eV or less) as some peaks are really close to each other and high efficiency in the low-end of the X-ray energy spectrum - typically, efficiency is >25% in the 1 to 25 keV range but my detector covers energies all the way up to 60+ keV at a reduced efficiency.</span></p><p><span style="font-family: verdana;">The required resolution and energy range are normally outside of the capabilities of most Gamma Spectroscopy detectors. Even the thin-crystal GS probes designed for the X-ray region will not have the resolution needed - some limited XRF might still be possible though.</span></p><p><span style="font-family: verdana;"> A specialized semiconductor <b>X-Ray detector device</b> is needed - Si-PIN, SDD or CdTe detector.</span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-Tesj0YJlYgo/YIvnw319n4I/AAAAAAAAPNM/d6ZTwu3edkgUuAzKwuaIMBnMYfo1NnPYgCLcBGAsYHQ/s956/XRF_detector_diagram2.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="831" data-original-width="956" src="https://1.bp.blogspot.com/-Tesj0YJlYgo/YIvnw319n4I/AAAAAAAAPNM/d6ZTwu3edkgUuAzKwuaIMBnMYfo1NnPYgCLcBGAsYHQ/s320/XRF_detector_diagram2.jpg" width="320" /></a></div><p></p><p><span style="font-family: verdana;">These detectors are very expensive, complex and very delicate devices employing a thin and very fragile (0.5 mil or less) Beryllium window and are usually evacuated or filled with low-pressure Helium gas. Inside the detector device are housed many components: the Si-PIN or SDD detector semiconductor chip, an input FET transistor for the preamp, a temperature sensor, a built-in multi-stage thermo-electric cooler (TEC) with a delta of ~85°C which reduces thermal noise in the detector chip and a temperature sensor. The heat pumped out from the chip must be constantly dissipated in the environment thru the mounting stud and the component's back surface thermal interface.</span></p><p><span style="font-family: verdana;">The detector is connected to a <b>charge-sensitive pre-amplifier</b> and the output of the pre-amp is fed into a <b>Digital Pulse Processor (Dpp)</b> which does the pulse detection, pulse shaping, ADC and pulse-sorting as it has a built-in <b>Multi-Channel Analyzer (MCA) </b>(8k channels). </span></p><p><span style="font-family: verdana;">A <b>Power Supply module</b> generates the bias for the detector, the power to the TEC module and controls the temperature of the detector chip, besides powering the pre-amp and Dpp.</span></p><p><span style="font-family: verdana;"><i>Because of the very low Characteristic X-Ray energies of light elements it can be extremely difficult to detect these elements as their secondary X-rays are easily absorbed even by air - lightest elements emit energies <1keV.</i></span></p><p><span style="font-family: verdana;"><i> High-Intensity primary x-ray beam, very thin Be-window, Silicon-Drift Diode (SDD) detector, vacuum chambers and even Helium-filled test chambers are often needed for elements lighter than Potassium to be detected.</i></span></p><p><span style="font-family: verdana;"><i>Typical Si-PIN detectors work well for elements heavier than Scandium (Z>21) but I am actually able to observe even the Calcium lines - not in great detail but visible in the spectrum.</i></span></p>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-9526223270640449322021-04-20T11:45:00.011-04:002023-12-16T10:36:00.555-05:00Gamma Spectroscopy - Lead Shielding / Castle v2<p><span style="font-family: verdana;">I decided to rebuild my Lead Castle / Test chamber for Gamma Spectroscopy. </span></p><p><span style="font-family: verdana;">The old vertical Lead Castle was working great but after awhile it became evident that the design is not the most convenient one, especially if it is used often - every time I needed to access the test chamber, I had to partially disassemble and remove most of the lead modules (which are also quite heavy) and then put everything back together. </span></p><p><span style="font-family: verdana;">Horizontal design is a more convenient option and creates a more accessible test chamber on the expense of the desktop footprint.</span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-8p-VPkWyTEI/YH74J_6nrEI/AAAAAAAAPHg/JcQaJVeLH-4X7jm8nMav-LfLNS3i-TFagCLcBGAsYHQ/s2048/20210406_213924.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1421" height="320" src="https://1.bp.blogspot.com/-8p-VPkWyTEI/YH74J_6nrEI/AAAAAAAAPHg/JcQaJVeLH-4X7jm8nMav-LfLNS3i-TFagCLcBGAsYHQ/s320/20210406_213924.jpg" /></a></div><span style="font-family: verdana;">I redesigned the castle so I can use some components from the old castle - the detector is also in a horizontal position and can stay in place while I am only manipulating the sample and the end-cap shielding.</span><div><span style="font-family: verdana;"><br /></span></div><div><span style="font-family: verdana;">There are 3 main shielding components - outer sleeve, </span><span style="font-family: verdana;">inner sleeve</span><span style="font-family: verdana;"> and end-cap.</span></div><div><p></p><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><br /></div><a href="https://1.bp.blogspot.com/-tmGtyrN921w/YH7uFxpL-UI/AAAAAAAAPGw/5_z86t7SV5oh61tmvYfMNCD0TXwJE9XNgCLcBGAsYHQ/s2048/Shield_outer.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1764" height="320" src="https://1.bp.blogspot.com/-tmGtyrN921w/YH7uFxpL-UI/AAAAAAAAPGw/5_z86t7SV5oh61tmvYfMNCD0TXwJE9XNgCLcBGAsYHQ/s320/Shield_outer.jpg" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">For the new design I reused the main shielding sleeve from the old chamber - 6" long Schedule 40 PVC pipe with 4" diameter. There is about 0.5mm of copper foil wound directly around the plastic form and almost 1" of Lead (rolled sheet with 1/8" thickness). </div><div style="text-align: center;">The whole package is tightly wrapped with duct tape. The overall outer diameter is 6". </div><div style="text-align: center;">The outer shield doubles the amount of lead around the test chamber and the detector's NaI(Tl) crystal in this configuration.</div></span><div><span style="font-family: verdana;"><br /></span><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-coygCPENoBw/YH7tuRjXqdI/AAAAAAAAPGo/rpvbOfJtOuU0_5gIwOVcRE0D9RPKV2p6gCLcBGAsYHQ/s2048/20210406_214220.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1495" height="320" src="https://1.bp.blogspot.com/-coygCPENoBw/YH7tuRjXqdI/AAAAAAAAPGo/rpvbOfJtOuU0_5gIwOVcRE0D9RPKV2p6gCLcBGAsYHQ/s320/20210406_214220.jpg" /></span></a></div><p></p><p style="text-align: center;"><span style="font-family: verdana;">For the inner shield I used 12" long section of 2" copper pipe and wound 5 turns of 1/8" thickness Lead sheet. Again, everything is tightly wrapped and covered with duct tape. </span></p><p style="text-align: center;"><span style="font-family: verdana;">The inner shielding is twice as long as the outer sleeve (12" vs 6") and shields the length of the entire detector assembly.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-Ws4l5aAFDFU/YH7y2F1IKzI/AAAAAAAAPG4/VIW9y0KWryAUAFMvynB7n7NJUqX_PlwxwCLcBGAsYHQ/s2048/20210406_214117.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1414" data-original-width="2048" src="https://1.bp.blogspot.com/-Ws4l5aAFDFU/YH7y2F1IKzI/AAAAAAAAPG4/VIW9y0KWryAUAFMvynB7n7NJUqX_PlwxwCLcBGAsYHQ/s320/20210406_214117.jpg" width="320" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">I built a special, custom wooden crate to hold the lead shielding. The base is made of 3/4" pine 6" x 16". The two sides around the large lead sleeve are glued and screwed with 2" 1/2 long decking screws to the base. </div><div style="text-align: center;">Two threaded rods, inserted in transparent vinyl tubing, together with washers and nuts re-enforce the top part, maintain the spacing of the sides while allowing the outer sleeve to be removed from the top after the inner sleeve is removed thru the front or the back. The front threaded rod (which also has a larger diameter) doubles as the front carry handle.</div></span><div><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-7Zx5OXq51tE/YH70h6BLv1I/AAAAAAAAPHA/YKtO3O5T9QMfFui5gO1tM-k_a83cQ_hYACLcBGAsYHQ/s2048/20210406_214157.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="1243" data-original-width="2048" src="https://1.bp.blogspot.com/-7Zx5OXq51tE/YH70h6BLv1I/AAAAAAAAPHA/YKtO3O5T9QMfFui5gO1tM-k_a83cQ_hYACLcBGAsYHQ/s320/20210406_214157.jpg" width="320" /></span></a></div><div style="text-align: center;"><span style="font-family: verdana;">The rear portion is a boxed off extension and it has 3/4 pine raiser on which the inner sleeve lays on so it aligns with the outer sleeve. A second carry handle is attached to the top of this box.</span></div><div style="text-align: center;"><span style="font-family: verdana;">Assembly takes place in reverse order. Outer sleeve is dropped from the top into place and then the inner sleeve is inserted.</span></div><div><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-UaPQKrQxo0U/YH71MTGTZNI/AAAAAAAAPHI/9TBASXZXf6IaHrML7I4kAYR2ePtv3UQXwCLcBGAsYHQ/s2048/20210406_214020.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1463" height="320" src="https://1.bp.blogspot.com/-UaPQKrQxo0U/YH71MTGTZNI/AAAAAAAAPHI/9TBASXZXf6IaHrML7I4kAYR2ePtv3UQXwCLcBGAsYHQ/s320/20210406_214020.jpg" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">The 6" long second box section sits on top of the base and the inner sleeve rests on it. It is attached to the base from the bottom side with the same long decking screws and wood glue. A 1" "lip" is left on the back to support a lead shield cap. </div></span><div><span style="font-family: verdana;"><br /></span></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-Y2LBcNvUrmI/YH71pjI-plI/AAAAAAAAPHQ/-hWJNp4mabEwYUQtUq9Lo5azpw7aNW5fwCLcBGAsYHQ/s2048/20210406_213758.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1259" height="320" src="https://1.bp.blogspot.com/-Y2LBcNvUrmI/YH71pjI-plI/AAAAAAAAPHQ/-hWJNp4mabEwYUQtUq9Lo5azpw7aNW5fwCLcBGAsYHQ/s320/20210406_213758.jpg" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">This is the end through which the GS detector is inserted and the detector position is adjusted inside the copper tube lining in order to place the front face of the crystal right against the sample.</div></span></div><div><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-o40D2EkLfUk/YH72F6d1O7I/AAAAAAAAPHY/ON9bNSyGSVoKRcRbZIDewTyTiOz--_EegCLcBGAsYHQ/s2048/20210406_213730.jpg" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: verdana;"><img border="0" data-original-height="2048" data-original-width="1363" height="320" src="https://1.bp.blogspot.com/-o40D2EkLfUk/YH72F6d1O7I/AAAAAAAAPHY/ON9bNSyGSVoKRcRbZIDewTyTiOz--_EegCLcBGAsYHQ/s320/20210406_213730.jpg" /></span></a></div><span style="font-family: verdana;"><div style="text-align: center;">The front end of the chamber with the inner sleeve nested inside the outer sleeve. The white front face of the detector is visible inside the copper lining. </div><div style="text-align: center;">The bottom of both compartments is lined with 1/8" rubber lining. The threaded rod on top is a structural components as the whole crate becomes very heavy (~65 Lbs.) and it acts as a handle as well.</div></span><div><span style="font-family: verdana;"><br /></span></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-NVP1vd-DogY/YH75fwMkWXI/AAAAAAAAPHo/w9gZYmO8s0o_AaVLcIb52ra9vBrNuUwkgCLcBGAsYHQ/s2048/20210406_213631.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1312" height="320" src="https://1.bp.blogspot.com/-NVP1vd-DogY/YH75fwMkWXI/AAAAAAAAPHo/w9gZYmO8s0o_AaVLcIb52ra9vBrNuUwkgCLcBGAsYHQ/s320/20210406_213631.jpg" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">After the test sample is placed in the chamber, a cover made of 6"x 6 x 1/4" Lead plate and 6" x 4" x 1/8" copper plate (towards the chamber) is used to close the opening of the chamber and another 1.5" inches of lead bricks are stacked. The front lead cap on the detector side has an opening for the coaxial cable.</div></span></div><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-OpO1aQNyC0g/YH759qL_22I/AAAAAAAAPHw/DJKrnKhkN2oQ1YcswGtHXsLnUhQFg9DnQCLcBGAsYHQ/s2048/20210406_213850.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1181" data-original-width="2048" src="https://1.bp.blogspot.com/-OpO1aQNyC0g/YH759qL_22I/AAAAAAAAPHw/DJKrnKhkN2oQ1YcswGtHXsLnUhQFg9DnQCLcBGAsYHQ/s320/20210406_213850.jpg" width="320" /></a></div><div><div style="text-align: center;"><span style="font-family: verdana;">The complete lead castle (v2). 4 rubber feet are installed on the bottom of the base.</span></div></div></div><div style="text-align: center;"><span style="font-family: verdana;">While this design puts slightly less lead (5-7mm less) around the crystal than the vertical design (with cast inner shielding), it is much more convenient to use and operate.</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/--H6yFm3vc20/YH7_Cg0MFtI/AAAAAAAAPH4/CGTd_tZUtg44pG11pVtcZMe8S45zRWw2QCLcBGAsYHQ/s2048/20210406_213702.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1152" data-original-width="2048" src="https://1.bp.blogspot.com/--H6yFm3vc20/YH7_Cg0MFtI/AAAAAAAAPH4/CGTd_tZUtg44pG11pVtcZMe8S45zRWw2QCLcBGAsYHQ/s320/20210406_213702.jpg" width="320" /></a></div><span style="font-family: verdana;">Two coats of polyurethane varnish as a finishing touch.</span><br /><span style="font-family: verdana;"><br /></span></div></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com1tag:blogger.com,1999:blog-5557902467288736826.post-3188552292259209272021-03-03T21:07:00.022-05:002022-08-05T21:50:59.826-04:00Eberline ASP-1 LED modification - "visual pulse indicator"<p><span style="font-family: verdana;">Eberline ASP-1 is one my favorite "80s era" Geiger Counters. </span></p><p><span style="font-family: verdana;">The electrical design is elegant, downright beautiful. ASP stands for "Analog Smart Portable" but "Analog" refers only to the metering system - the counter is actually digital with an 8-bit microcontroller (Intel 80C31 @ 6MHz), firmware with a very robust algorithm, stored on 27C32 EPROM, an AD7524 8-bit DAC to drive the metering system and multiplexed read of the ranges and configuration dip-switches. Functionality-wise it is way more advanced and more flexible instrument than Ludlum Model 3, with a lot more features, measurement units and ranges and far more sophisticated circuitry.</span></p><p><span style="font-family: verdana;">The speaker of the unit is not terribly loud - it is more of an acoustic air-tube type headphone transducer than a proper loud speaker.</span></p><p><span style="font-family: verdana;">I decided to add a "visual click" with a LED, just like the one found on the more modern counters. As I mentioned the electrical design is beautiful and it wasn't difficult to figure out how to implement this mod.</span></p><p><span style="font-family: verdana;">The good news is that it is super-easy to mount the LED from a mechanical stand point as well - since the metering system has a backlight feature there is absolutely no need to modify the case - this is a slick "no drilling", very unobtrusive mod.</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-V4o80Vl7mb4/YEAu7KHoPDI/AAAAAAAAOhE/zN8oMP7exikoD8kcv0--3ieMSJY6mndEwCLcBGAsYHQ/s2048/Eberline_LED_On.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1752" height="320" src="https://1.bp.blogspot.com/-V4o80Vl7mb4/YEAu7KHoPDI/AAAAAAAAOhE/zN8oMP7exikoD8kcv0--3ieMSJY6mndEwCLcBGAsYHQ/s320/Eberline_LED_On.jpg" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">The LED is mounted behind the metering system and projects the light on the white, semi-translucent meter backing, using it basically as a "projection screen".</div></span><div><br /></div><div><span style="font-family: verdana;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-uD_1ufWrMMQ/YEA9IJUQbAI/AAAAAAAAOhM/2sgY7I4YXCwj2WnIXWBkFZZ-sHvgEs5ygCLcBGAsYHQ/s2048/Eberline_LED_off.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1754" height="320" src="https://1.bp.blogspot.com/-uD_1ufWrMMQ/YEA9IJUQbAI/AAAAAAAAOhM/2sgY7I4YXCwj2WnIXWBkFZZ-sHvgEs5ygCLcBGAsYHQ/s320/Eberline_LED_off.jpg" /></a></div><div style="text-align: center;">When the LED is off, the metering system looks just like before.</div><div><span style="font-family: verdana;"><br /></span></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-A8os7mETvrw/YEA9fo8UxpI/AAAAAAAAOhU/8wjllpmzpIgMaZkb2_dlu38fxdBxCD1XQCLcBGAsYHQ/s2048/Eberline%2BLED_mount.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1815" height="320" src="https://1.bp.blogspot.com/-A8os7mETvrw/YEA9fo8UxpI/AAAAAAAAOhU/8wjllpmzpIgMaZkb2_dlu38fxdBxCD1XQCLcBGAsYHQ/s320/Eberline%2BLED_mount.jpg" /></a></div><div style="text-align: center;">Behind the scenes. </div><div style="text-align: center;">The Anode of the LED is connected to a wire, junction is heat-shrink insulated and then mechanically attached with hot glue to the PCB, just behind the metering system. The LED Cathode is connected with a 220 Ohm resistor to the GND lead (the left lead on the picture) of the Speaker Switch and this is also a second anchor point, providing mechanical rigidity.</div><span style="font-family: verdana;"><br /></span></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-2_2JB0bx_PU/YEA-e4mGfyI/AAAAAAAAOhc/i3iah4m0sJQkaDLMuoI3U4Ppuf8f_QbKACLcBGAsYHQ/s2048/Eberline_LED_connection%2B2.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1657" height="320" src="https://1.bp.blogspot.com/-2_2JB0bx_PU/YEA-e4mGfyI/AAAAAAAAOhc/i3iah4m0sJQkaDLMuoI3U4Ppuf8f_QbKACLcBGAsYHQ/s320/Eberline_LED_connection%2B2.jpg" /></a></div><div style="text-align: center;">The Anode lead wire of the LED is connected to junction point between R138, R139 and pins 1,2,4 of A104 (CD4001B) on the bottom of the PCB.</div></div><div><span style="font-family: verdana;"><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-KO9liaVnenk/YEA-eybql-I/AAAAAAAAOhg/2hUpavZ87xgZR8FJ3opY-W-kMTKZC4I1ACLcBGAsYHQ/s2048/Eberline_LED_connection1.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1363" height="320" src="https://1.bp.blogspot.com/-KO9liaVnenk/YEA-eybql-I/AAAAAAAAOhg/2hUpavZ87xgZR8FJ3opY-W-kMTKZC4I1ACLcBGAsYHQ/s320/Eberline_LED_connection1.jpg" /></a></div></div><div style="text-align: center;">The wire is secured with hot glue dabs to the PCB and uses the notch of the edge connector to transition PCB sides.</div></span><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-m56auqoycPg/YEA_kFCM0KI/AAAAAAAAOhs/tLDMZJS8WBo_9hCpG1pLlUfWn9bvDd40wCLcBGAsYHQ/s2048/Eberline_LED_mod.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1171" data-original-width="2048" src="https://1.bp.blogspot.com/-m56auqoycPg/YEA_kFCM0KI/AAAAAAAAOhs/tLDMZJS8WBo_9hCpG1pLlUfWn9bvDd40wCLcBGAsYHQ/s320/Eberline_LED_mod.jpg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">This schematics shows how the LED is integrated in the electrical circuit.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: left;"><span style="font-family: verdana;">The mod is using the speaker circuit to pulse the LED as this circuit is designed to provide long enough pulses (~2 ms) for the speaker, using a free-running 2kHz generator and a mono-stable trigger. </span></div><div class="separator" style="clear: both; text-align: left;"><span style="font-family: verdana;">The pulses behind the pre-amp which are counted by the MCU are extremely short (just a few uSec) and they will not light up the LED for a long enough time to be visible. Using the audio circuit not only solves this problem but takes advantage of the AES-1 ability to divide high click-rates with user-selectable division factor (when a scintillating detector is used for example).</span></div><p><span style="font-family: verdana;">The LED will light up permanently if an Alarm condition (Overload) occurs.</span></p><p><span style="font-family: verdana;">Turning the Audio feature off will disable the visual pulse indicator as well but the Alarm indication will still work as designed and the LED will still respond to an alarm condition.</span></p></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0tag:blogger.com,1999:blog-5557902467288736826.post-54034647177782726692021-02-19T17:45:00.005-05:002022-08-04T12:13:53.360-04:00SE International Radiation Alert Ranger - making "protective cap accessories".<p><span style="font-family: verdana;">One thing I really like about the design of the SE International Radiation Alert Ranger is the protective cap on the back for the "pancake" detector.</span></p><p><span style="font-family: verdana;">This cap is great to protect the delicate mica window from contamination and mechanical events that can destroy the detector.</span></p><p><span style="font-family: verdana;">I realized that this cap can easily be turned into a useful "charged particle filter" or even a check-source.</span></p><p><span style="font-family: verdana;">I went ahead and ordered a few spare caps from SE International at $1.50 a piece.</span></p><p><span style="font-family: verdana;"></span></p><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><a href="https://1.bp.blogspot.com/-FziSe6selik/YDA3aCXcZZI/AAAAAAAAOc8/hVo6Wp85_xo4YRy-pIyVq82KOaiHSRQKgCLcBGAsYHQ/s2048/20210203_154502.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1807" height="320" src="https://1.bp.blogspot.com/-FziSe6selik/YDA3aCXcZZI/AAAAAAAAOc8/hVo6Wp85_xo4YRy-pIyVq82KOaiHSRQKgCLcBGAsYHQ/s320/20210203_154502.jpg" /></a></span></div><span style="font-family: verdana;"><div style="text-align: center;">The assortment of "cap accessories I made - a check-source, an Alpha filter and an Alpha + Beta filter. The Alpha filter is used for Beta + Gamma measurements and the Alpha + Beta filter is used to measure Gamma only.</div><div style="text-align: center;"> </div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-v6hbe0zAIyg/YDA426P_BxI/AAAAAAAAOdI/e1RMWWr3tG0pq32xFqcOOKVxJK1SPzXAgCLcBGAsYHQ/s2048/20210203_154304.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1240" data-original-width="2048" src="https://1.bp.blogspot.com/-v6hbe0zAIyg/YDA426P_BxI/AAAAAAAAOdI/e1RMWWr3tG0pq32xFqcOOKVxJK1SPzXAgCLcBGAsYHQ/s320/20210203_154304.jpg" width="320" /></a></div>The "Alpha Filter" (the cap with the black insert) is made by cutting a disk of self-adhesive aluminum foil (thickness 0.1mm) and applying it on the inside of the cap. The foil in combination with the plastic of the cap will stop all alphas, while letting most betas come trough. Adding the thin aluminum foil is not "a must" as the plastic of the cap will be completely sufficient to block Alphas but it can double as a "soft beta" filter as well.</div><div style="text-align: center;"><br /></div><div style="text-align: left;">For the "Alpha filter", thicker cooking foil can be used as well and attached with double-sided adhesive tape or glue.</div></span><p></p><div data-reddit-rtjson="{"entityMap":{},"blocks":[{"key":"4nc8s","text":"Some additional comments:","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"193v4","text":"Regarding the \"Check-source\" cap:","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"18eaq","text":"It is very important for the autunite crystal to be completely sealed in epoxy so no radon can escape and contaminate the mica window of the pancake detector.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"rc4a","text":"I used NORM for the source for 2 reasons - I don't have to worry about half-life and changes of the activity over time and secondly, I wanted to have a very low activity check-source. The lowest activity Cs-137 I have at hand is 1 uCi so I went the NORM route instead.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"1kf36","text":"Alternatively (and it would be even better), one can attach a Spectrum Technique sealed Cs-137 check-source disk on the inside of the cap - like 0.05 uCi or 0.1 uCi .","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"138ii","text":"For the \"Alpha filter\", thicker cooking foil can be used and attached with double-sided adhesive tape.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"q8u4","text":"For the \"Alpha + Beta\" filter, I cut the disk out of equipment rack blank panel. The aluminum of the blank is 3 mm thick which stops all beta particles with energy up to 2 MeV and has very low Gamma attenuation (less than 7%) for the Cs-137 isotope (662 keV).","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"2ec5g","text":"As an alternative, pure 1 mm Pb sheet will stop betas up to 2.3 MeV and will attenuate Cs-137 gamma by 10%, Co-60 Gamma by 5% and not only the math is easier but it is much easier to cut than 3mm aluminum - one can use regular scissors for such thin lead sheet.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"2133k","text":"The plastic of the cap should slow down beta particles a bit perhaps reducing the generation of secondary X-Rays (from the Bremsstrahlung effect)","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"b4eqp","text":"Inserts made out of other materials can be made to fit these protective caps - I'll be making another cap with a 3 mm thick lead sheet insert for measuring extremely high activity gamma sources (normally the Ranger overflows at 350K CPM). By calculating the attenuation factor of the lead in the cap, I can correct the measurements which will extend the maximum range of the instrument. For example 1/8\" Lead (3.1mm) will attenuate Cs-137 Gamma rays by 28% and Co-60 by 14%","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}}]}"><div data-block="true" data-editor="2f1f8d" data-offset-key="404bf-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="404bf-0-0" style="text-align: center;"><span data-offset-key="404bf-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-WFUG0yh91mQ/YDA6a7BXzcI/AAAAAAAAOdU/K4x-KWWkIksfrbuYwFB3gkOws8_DwBh3QCLcBGAsYHQ/s2048/20210203_154402.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1737" height="320" src="https://1.bp.blogspot.com/-WFUG0yh91mQ/YDA6a7BXzcI/AAAAAAAAOdU/K4x-KWWkIksfrbuYwFB3gkOws8_DwBh3QCLcBGAsYHQ/s320/20210203_154402.jpg" /></a></div><span style="font-family: verdana;">The "Alpha + Beta" filter (gray) is made by cutting a disk out of aluminum. The disk is a tad small than 1" 3/4 and thickness is 3mm. This disk is secured inside the cap with a piece of double-sided adhesive tape.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="404bf-0-0" style="text-align: center;"><span data-offset-key="404bf-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="404bf-0-0" style="text-align: center;"><span data-offset-key="404bf-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-Fo1ptY_kBsM/YDA7VNWgcFI/AAAAAAAAOdc/M-tSqzxsTMgsqGuqqULVMjw2MOim03daACLcBGAsYHQ/s2048/20210203_154146.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1152" height="320" src="https://1.bp.blogspot.com/-Fo1ptY_kBsM/YDA7VNWgcFI/AAAAAAAAOdc/M-tSqzxsTMgsqGuqqULVMjw2MOim03daACLcBGAsYHQ/s320/20210203_154146.jpg" /></a></div><span style="font-family: verdana;">The "Alpha" filter (top) is placed for measuring Beta + Gamma activity only. The "Alpha + Beta" filter (bottom) in addition shields all Betas up to 2 MeV and attenuates Gamma <7 % @662 keV (Cs-137)</span><br /><span style="font-family: verdana;"><br /></span><div data-block="true" data-editor="2f1f8d" data-offset-key="4ornd-0-0" style="text-align: left;"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="4ornd-0-0"><span data-offset-key="4ornd-0-0"><span style="font-family: verdana;">For the "Alpha + Beta" filter, I cut the disk out of equipment rack blank panel. The aluminum of the blank is 3 mm thick which stops all beta particles with energy up to 2 MeV and has very low Gamma attenuation (less than 7%) for the Cs-137 isotope (662 keV).</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="4ornd-0-0"><br /></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="4ornd-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-bk820ZPhvRE/YDBSZz44USI/AAAAAAAAOd0/nvSHWUniTRsmQoz8F-ktPNLhFZYI6fKsgCLcBGAsYHQ/s2048/20210219_185355.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1537" height="320" src="https://1.bp.blogspot.com/-bk820ZPhvRE/YDBSZz44USI/AAAAAAAAOd0/nvSHWUniTRsmQoz8F-ktPNLhFZYI6fKsgCLcBGAsYHQ/s320/20210219_185355.jpg" /></a></div></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="4ornd-0-0" style="text-align: center;"><span data-offset-key="4ornd-0-0"><span style="font-family: verdana;">Cutting a perfect, large (1" 3/4) disk out of 3mm aluminum is a bit of a chore but nothing that can't be solved by a drill press, a grinding wheel and a file.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="4ornd-0-0" style="text-align: center;"><span data-offset-key="4ornd-0-0"><span style="font-family: verdana;"><br /></span></span></div></div><div data-block="true" data-editor="2f1f8d" data-offset-key="1enhk-0-0" style="text-align: left;"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="1enhk-0-0"><span data-offset-key="1enhk-0-0"><span style="font-family: verdana;">As an alternative, pure 1 mm Lead (Pb) sheet will stop betas up to 2.3 MeV and will attenuate Cs-137 gamma by 10%, Co-60 Gamma by 5% and not only the math is easier but it is much easier to cut than 3mm aluminum - one can use regular scissors for such thin lead sheet.</span></span></div></div><div data-block="true" data-editor="2f1f8d" data-offset-key="cd86v-0-0" style="text-align: left;"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="cd86v-0-0"><span data-offset-key="cd86v-0-0"><span style="font-family: verdana;">The plastic of the cap should slow down beta particles a bit perhaps reducing the generation of secondary X-Rays (from the Bremsstrahlung effect)</span></span></div></div><div data-block="true" data-editor="2f1f8d" data-offset-key="7ag8b-0-0" style="text-align: left;"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="7ag8b-0-0"><span data-offset-key="7ag8b-0-0"><span style="font-family: verdana;">Inserts made out of other materials can be made to fit these protective caps - I'll be making another cap with a 3 mm thick lead sheet insert for measuring extremely high activity gamma sources (normally the Ranger overflows at 350K CPM). </span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="7ag8b-0-0"><span data-offset-key="7ag8b-0-0"><span style="font-family: verdana;">By calculating the attenuation factor of the Lead in the cap, I can correct the measurements which will extend the maximum range of the instrument. For example 1/8" Lead (3.1mm) will attenuate Cs-137 Gamma rays by 28% and Co-60 by 14% and this can be used as a crude dose rate correction.</span></span></div></div><span style="font-family: verdana;"><br /></span><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-6QDO-dhSmSI/YDA8pNfxp3I/AAAAAAAAOdo/V-xey_O9T6oYsp3hxFkK-s3aiY-dVHqSgCLcBGAsYHQ/s2048/20210203_160612.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="2023" height="320" src="https://1.bp.blogspot.com/-6QDO-dhSmSI/YDA8pNfxp3I/AAAAAAAAOdo/V-xey_O9T6oYsp3hxFkK-s3aiY-dVHqSgCLcBGAsYHQ/s320/20210203_160612.jpg" /></a></div><span style="font-family: verdana;">The Check-Source Cap using an epoxy sealed tiny Autunite crystal.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="404bf-0-0" style="text-align: center;"><span data-offset-key="404bf-0-0"><span style="font-family: verdana;">The Autunite crystal is placed on a piece of aluminum foil substrate and suspended inside a drop of epoxy. I made a shallow cavity in the plastic to accommodate the epoxy drop and after trimming the foil it is attached on the inside of the cap with Kapton tape. The source produces around 600 CPM when the cap is in place.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="404bf-0-0" style="text-align: center;"><br /></div></div><div data-block="true" data-editor="2f1f8d" data-offset-key="7qamd-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="7qamd-0-0"><span data-offset-key="7qamd-0-0"><span style="font-family: verdana;">It is very important for the Autunite crystal to be completely sealed inside the epoxy drop so no radon can quickly escape and contaminate the mica window of the pancake detector. In addition, this cap is normally stored in the carry pouch and only used as needed.</span></span></div></div><div data-block="true" data-editor="2f1f8d" data-offset-key="4tbie-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="4tbie-0-0"><span data-offset-key="4tbie-0-0"><span style="font-family: verdana;">I used N.O.R.M. for the source for 2 reasons - I don't have to worry about half-life and changes of the activity over time and secondly, I wanted to have a very low activity check-source that I have no problem carrying around and traveling with. Unfortunately, the lowest activity Cs-137 disk source I have at hand is 1 uCi so I just went the NORM route instead.</span></span></div></div><div data-block="true" data-editor="2f1f8d" data-offset-key="8o2qj-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="8o2qj-0-0"><span data-offset-key="8o2qj-0-0"><span style="font-family: verdana;">Alternatively (and it actually would be even better), one can attach a Spectrum Technique sealed Cs-137 disk source on the inside of the cap - something like 0.05 uCi or 0.1 uCi or even a tiny slab of uranium glass - the larger cap is just more difficult to lose and easier to work with acting as a "holder' for the source.</span></span></div></div></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com1tag:blogger.com,1999:blog-5557902467288736826.post-16727238376626527192021-02-18T20:38:00.043-05:002023-08-09T10:49:52.267-04:00Ludlum GM Counter Calibration for accurate CPM rate using a Function Generator<p><span style="font-family: verdana;">I have a few Geiger counters (Ludlum and Eberline) with Analog Metering Systems and wanted to make sure they are properly calibrated to display the CPM rate.</span></p><p><span style="font-family: verdana;">I am not interested in dose rates as they are more or less meaningless when working with NORM (Natural Occurring Radioactive Materials). These is a mixture of isotopes, each emitting different particles and gamma energies and a Geiger Counter cant provide an accurate estimate for the dose since it is not an energy-discriminating instrument.</span></p><p><span style="font-family: verdana;">Geiger Counters are usually calibrated to display doses from a specific isotope / energy - most often Cs-137 or Co-60, while I am interested in the relative activity of the samples so accurate CPM rates are more important to me. Furthermore, the dose calibration is taking place right on the scale where specific CPM rate equates to a dose based on the efficiency of the probe.</span></p><p><span style="font-family: verdana;">Fortunately, all counters using an Analog Metering System / Scale are equipped with one or more trimmer-potentiometers to calibrate the needle reading to the registered count rate. </span></p><p><span style="font-family: verdana;">The metering system is nothing more than a mA-meter or uA-meter and the counter's circuitry converts count rate to a specific current which will deflect the needle to a specific rate marked on the scale.</span></p><p><span style="font-family: verdana;">Digital counters also can benefit from this setup if their analog front-end (amplifier) / pulse detection circuit allows for adjustments.</span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-r9dWB0CD9W8/YC949b7Um2I/AAAAAAAAOcs/fbhUi_wE0BkJ4UgAYAqnVgAoikq8HOSbgCLcBGAsYHQ/s1241/Ludlum-500.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1068" data-original-width="1241" src="https://1.bp.blogspot.com/-r9dWB0CD9W8/YC949b7Um2I/AAAAAAAAOcs/fbhUi_wE0BkJ4UgAYAqnVgAoikq8HOSbgCLcBGAsYHQ/s320/Ludlum-500.jpg" width="320" /></a></div><p></p><p><span style="font-family: verdana;">Ludlum makes their Model 500 Pulse Generator for this type of calibration but it is ridiculously priced (a used one sold recently on eBay for $2100) and after studying the schematics of this overpriced monstrosity (which also seems to have been designed at least 20-30 years ago) , I concluded that using a modern Function Generator in Pulse mode will do an even better job and way more accurately, while providing more or less identical functionality. The Ludlum Pulse Generator allows for HV adjustment, besides rate calibration but this can easily be done with an inexpensive Fluke 80K-6 HV Probe and a multimeter (an even better option would be Fluke 80K-40 probe since it has 1GOhm impedance and it will cause much lower voltage drop in the HV PS circuit thus less measurement error).</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-hdRS4XVtm1o/YC8MDFrWB1I/AAAAAAAAOaM/B-XQLqiq1YAoBl1E8lbV0oM7571Tw9rwwCLcBGAsYHQ/s2048/20210217_164505.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1774" height="320" src="https://1.bp.blogspot.com/-hdRS4XVtm1o/YC8MDFrWB1I/AAAAAAAAOaM/B-XQLqiq1YAoBl1E8lbV0oM7571Tw9rwwCLcBGAsYHQ/s320/20210217_164505.jpg" /></a></div><div style="text-align: center;"> <span style="font-family: verdana;">This is my setup for the CPM calibration of Geiger Counters with an Analog Scale. The Function Generator simulates the GM tube inside the detector probe by sending out pulses with the correct shape and timing and polarity. </span></div><div style="text-align: center;"><span style="font-family: verdana;">The DC-blocking cap protects the output of the generator from being blown up by the High-Voltage tube bias coming from the counter's HV PS. </span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-WB_9I_ikVu8/YC8QpL8aJsI/AAAAAAAAOaY/nJOO2cYE2Z8tytBOEnsyvisklwSL8cNagCLcBGAsYHQ/s2048/20210217_162653.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1152" data-original-width="2048" src="https://1.bp.blogspot.com/-WB_9I_ikVu8/YC8QpL8aJsI/AAAAAAAAOaY/nJOO2cYE2Z8tytBOEnsyvisklwSL8cNagCLcBGAsYHQ/s320/20210217_162653.jpg" width="320" /></a></div></div><div data-reddit-rtjson="{"entityMap":{"0":{"type":"LINK","mutability":"MUTABLE","data":{"url":"https://youtu.be/MAcpOhnbGk4"}}},"blocks":[{"key":"m0se","text":"This is my setup for CPM calibration of Geiger Counters with an Analog Scale.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"3935t","text":"Ludlum makes their Model 500 Pulser for this calibration but it is ridiculously priced (a used one sold on ebay for $2100) and after studying the schematics of this over-priced monstrosity I concluded that using a Function Generator in Pulse mode will do the job even better.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"4k03a","text":"I setup my Func Genrator (Rigol Technologies DG1022Z) with the same parameter pulses the Ludlum 500 produces - Pulse width is 4 uSec, leading edge 300 nSec and trailing edge 2.25 (Ludlum's pulser actually has trailing Edge at 5 uSec due to their crude circuit - I made my pulses slightly wider and more defined)","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"dss0n","text":"Amplitude is setup for 500 mVpp and output is inverted - GM tubes produce negative polarity pulses as the gas discharge just shunts the HV DC tube bias.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"2f575","text":"To block the DC bias and inject the pulses, simulating a GM tube with my generator, I inserted a HV capacitor inline - this protects my generator form the 900V DC bias generated by the Ludlum meter! I had some 10nF / 3 kV caps at hand and used two in series for 5nF / 6kV. Everything is well insulated to avoid a short that can damage my generator.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"8n1q8","text":"The calibration procedure is super simple - I select a scale on the Ludlum, dial the frequency and adjust the calibration pot until I get the correct reading. Then I move to the next range.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"8jr9c","text":"Here is a video of the Ludlum fed with 600 CPM (Scale x0.1) - 10.000 Hz from the generator.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[{"offset":0,"length":4,"key":0}],"data":{}},{"key":"fjhvv","text":"For slower rates - x0.1 scale the Ludlum should be placed on SLOW to average and smooth out the reading. For the higher rates FAST mode can be used just as well.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"6de3s","text":"Basically it cost me nothing to build this calibration setup - if I am to count the cost of the generator its mere $400 - not even 1/4 of the price of Ludlum 500 pulser.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"1v9ih","text":"The time-base of the generator is many times more accurate than the Ludlums voltage-to-freq converter used in their circuit.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"5cldo","text":"This calibration is for very accurate CPM rates and it will not be applicable for Dose rate calibration - the efficiency of the detector at certain gamma energies can not be measured without an actual gamma source.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"3pu12","text":"The generator simulates a GM tube and each pulse produced will be correctly counted over time by the meter as the rate is known, fixed and super-stable.","type":"unstyled","inlineStyleRanges":[],"entityRanges":[],"data":{}}]}"><div data-block="true" data-editor="43910b" data-offset-key="ftifu-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0" style="text-align: center;"><span data-offset-key="ftifu-0-0"><span style="font-family: verdana;">I setup my Function Generator (Rigol Technologies DG1022Z in my case) with almost the same parameters for the pulses as the Ludlum 500 Pulse Generator produces. Any function generator with a dedicated "Pulse Mode" will work. </span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0" style="text-align: center;"><span data-offset-key="ftifu-0-0"><span style="font-family: verdana;"><b>A square wave signal is not useable as the pulse width must remain constant while varying the frequency!</b><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0"><span data-offset-key="ftifu-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0"><span data-offset-key="ftifu-0-0"><span style="font-family: verdana;">Leading edge is set to 300 ns, </span></span><span style="font-family: verdana;">Pulse width is 4 μs</span><span style="font-family: verdana;"> and trailing edge 2.25 μs.</span><span style="font-family: verdana;"> (Ludlum's Pulser actually has a trailing edge of the pulses at 5 μs due to their circuit - I made my pulses wider and more defined with a steeper trailing edge instead but this aspect is fully adjustable with my Generator).</span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0"><span style="font-family: verdana;">GM tubes in general produce very short pulses as they are quenched by the halogen gas in the tube so they can reset for the next count and different tubes have different "dead time" - for example LND7311 in the Ludlum 44-9 is twice as faster (minimum dead-time of 20 μs) than its low-voltage "sibling" LND7317 (minimum dead-time 40 μs).</span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0"><span style="font-family: verdana;"><br /></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-seAZXDAU6wc/YC8R1zEwBZI/AAAAAAAAOak/8PfFnmutycAJqrbIrErMB4SR-Vswmy1aACLcBGAsYHQ/s2048/20210217_155706.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1330" height="320" src="https://1.bp.blogspot.com/-seAZXDAU6wc/YC8R1zEwBZI/AAAAAAAAOak/8PfFnmutycAJqrbIrErMB4SR-Vswmy1aACLcBGAsYHQ/s320/20210217_155706.jpg" /></a></div><div style="text-align: center;"><span style="font-family: verdana;">The shape of an individual pulse</span></div><div style="text-align: center;"><span style="font-family: verdana;"><br /></span></div><div style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-JOevUhWWEJY/YDGQzoYlV9I/AAAAAAAAOeE/9rT__HSDYwkoc9ppwXDJig7InPlzhzczwCLcBGAsYHQ/s2048/20210220_171150.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1210" data-original-width="2048" src="https://1.bp.blogspot.com/-JOevUhWWEJY/YDGQzoYlV9I/AAAAAAAAOeE/9rT__HSDYwkoc9ppwXDJig7InPlzhzczwCLcBGAsYHQ/s320/20210220_171150.jpg" width="320" /></a></div><span style="font-family: verdana;">Pulses with period 2ms (500.0 Hz) or 30K CPM. The scope is set to 1ms/div.</span><br /><span style="font-family: verdana;"><br /></span></div><span style="font-family: verdana;"><br /></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-blmYzty98KM/YC8ZbhDDl5I/AAAAAAAAObg/E-kDxhl2vcAMPW9u6W-F3jqEzU4TI2kgACLcBGAsYHQ/s2048/20210217_162847.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1152" data-original-width="2048" src="https://1.bp.blogspot.com/-blmYzty98KM/YC8ZbhDDl5I/AAAAAAAAObg/E-kDxhl2vcAMPW9u6W-F3jqEzU4TI2kgACLcBGAsYHQ/s320/20210217_162847.jpg" width="320" /></a></div></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0"><span style="font-family: verdana;">Amplitude is set for 500mVpp (peak-to-peak), and the Generator output is inverted - GM tubes produce negative polarity pulses as the gas discharge just shunts the HV DC tube bias to ground causing a brief voltage drop across the tube's anode resistor. The amplitude adjustment can also be varied to calibrate the pulse height threshold of the instrument (pulse sensitivity).</span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0"><span style="font-family: verdana;"><br /></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0" style="text-align: center;"><span style="font-family: verdana;"><b>Generator De-coupler / Pulse Injector</b></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0" style="text-align: center;"><span style="font-family: verdana;"><b><br /></b></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="ftifu-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-wg_YmlfMcn0/YC8S9P9shPI/AAAAAAAAOas/UURSxekHUm0vyPcjcjcQ6r2nin54cKGwwCLcBGAsYHQ/s2048/20210217_162732.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1466" data-original-width="2048" src="https://1.bp.blogspot.com/-wg_YmlfMcn0/YC8S9P9shPI/AAAAAAAAOas/UURSxekHUm0vyPcjcjcQ6r2nin54cKGwwCLcBGAsYHQ/s320/20210217_162732.jpg" width="320" /></a></div></div></div><div data-block="true" data-editor="43910b" data-offset-key="c6931-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="c6931-0-0" style="text-align: center;"><span data-offset-key="c6931-0-0"><span style="font-family: verdana;">To block the DC bias and inject the pulses, simulating a GM tube with my generator, I inserted a HV blocking capacitor inline - this protects the output of the generator form the 900V DC bias generated by the Ludlum meter.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="c6931-0-0" style="text-align: center;"><span data-offset-key="c6931-0-0"><span style="font-family: verdana;">At some point I'll make a little enclosure with tap points for oscilloscope and a high-voltage readings.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="c6931-0-0" style="text-align: center;"><span data-offset-key="c6931-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="c6931-0-0"><span data-offset-key="c6931-0-0"><span style="font-family: verdana;">I had some 10nF / 3 kV caps at hand and used two in series for total 5nF / 6kV. Alternatively single 5.6nF/ 3kV cap will work just as well - the voltage rating must be at least 3kV or more!</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="c6931-0-0"><span data-offset-key="c6931-0-0"><span style="font-family: verdana;">Everything is insulated to avoid a short that can damage my generator. Two Female BNC connectors are used to connect both cables thru the capacitor.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="c6931-0-0"><span data-offset-key="c6931-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="c6931-0-0"><span style="color: red; font-family: verdana;"><b>Important! - Failure to properly decouple / block the Geiger's DC bias from the Signal Generator's output will destroy your Signal Generator!</b></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="c6931-0-0"><span style="font-family: verdana;"><b><br /></b></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="c6931-0-0"><span style="font-family: verdana;">You can not simply connect the Geiger counter directly to the output of the Signal Generator - such mistake will cost your generator! <b>Use of a DC-blocking capacitor inline is an absolute must!</b> </span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="c6931-0-0"><span data-offset-key="c6931-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="c6931-0-0"><span data-offset-key="c6931-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-6VseFM2Qizc/YC8UWtkfgNI/AAAAAAAAOa4/u-zE_c8ZUbkK-MEx0kzBPrnfVnwY1gKwACLcBGAsYHQ/s2048/20210217_163326.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1188" height="320" src="https://1.bp.blogspot.com/-6VseFM2Qizc/YC8UWtkfgNI/AAAAAAAAOa4/u-zE_c8ZUbkK-MEx0kzBPrnfVnwY1gKwACLcBGAsYHQ/s320/20210217_163326.jpg" /></a></div></span></div></div><div data-block="true" data-editor="43910b" data-offset-key="f3bsr-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;">The calibration procedure is super simple - I select a scale on the Ludlum, dial the frequency on the generator and adjust the calibration trimmer-pot for this range until I get the correct reading on the analog metering system.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;">The generator's frequency is dialed as Freq (in Hz) = desired CPM rate, divided by 60. (the actual pulse frequency in Hz corresponds to the CPS rate) .</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;">The desired rate should be a rate located in the middle of each scale and re-checked with frequencies causing full needle deflection (end of scale) and little needle deflection (just around 5-10% past the beginning of the scale) . This will expose any non-linearity of the circuit/metering system.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;">In the picture 500.0 Hz signal is used to generate a pulse rate of 30 000 CPM (3K in the x10 scale).</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-11nZChGSUlU/YC8VXCrBeMI/AAAAAAAAObA/LEhUlXdJV9UV8isGeoyVe5wJ2YbrsCpsgCLcBGAsYHQ/s2048/20210217_163408.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1225" height="320" src="https://1.bp.blogspot.com/-11nZChGSUlU/YC8VXCrBeMI/AAAAAAAAObA/LEhUlXdJV9UV8isGeoyVe5wJ2YbrsCpsgCLcBGAsYHQ/s320/20210217_163408.jpg" /></a></div><span style="font-family: verdana;"><div style="text-align: center;">Full scale deflection on the x10 range is checked with 1.0 kHz signal for 60 000 CPM and it is "dead on" after a slight adjustment. </div></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-abHmtS4J9RA/YC8bmZLJyII/AAAAAAAAObs/BSxHK1xSlpMVoyEVRCCY-xkzcwEHlkFbQCLcBGAsYHQ/s2048/20210217_163805.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1180" height="320" src="https://1.bp.blogspot.com/-abHmtS4J9RA/YC8bmZLJyII/AAAAAAAAObs/BSxHK1xSlpMVoyEVRCCY-xkzcwEHlkFbQCLcBGAsYHQ/s320/20210217_163805.jpg" /></a></div><span style="font-family: verdana;">At the x1 scale, 50.0 Hz from the Generator should result in exactly 3000 CPM reading. The x1 trim-pot is adjusted to move the needle and match the markings on the scale if reading is initially off.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-c2idhLfI1Lg/YC8cehjn-xI/AAAAAAAAOcE/yORgdlK3UA4n2nMZ0EoHWxU-ZgWRF9mkgCLcBGAsYHQ/s2048/20210217_163645.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1152" height="320" src="https://1.bp.blogspot.com/-c2idhLfI1Lg/YC8cehjn-xI/AAAAAAAAOcE/yORgdlK3UA4n2nMZ0EoHWxU-ZgWRF9mkgCLcBGAsYHQ/s320/20210217_163645.jpg" /></a></div><span style="font-family: verdana;">Full deflection at the x1 range is then confirmed with 100.0 Hz signal</span><br /><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;">Each range is adjusted individually in the same manner - most meters have independent trimmer-pots. </span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.blogger.com/video.g?token=AD6v5dzuSkQE9UvIkkotQ3LGhdnGT4HVyQJCXz48cLA-vPsim7pADj3b5CouFlfDHuptsrIgHZVU-atZdOBKMesw1w' class='b-hbp-video b-uploaded' frameborder='0'></iframe></div></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="f3bsr-0-0"><span data-offset-key="f3bsr-0-0"><span style="font-family: verdana;"><br /></span></span></div></div><div data-block="true" data-editor="43910b" data-offset-key="2eoji-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="2eoji-0-0"><span style="font-family: verdana;"><span data-offset-key="2eoji-1-0">Here is a video of the Ludlum Model 14C counter driven with 600 CPM (Scale x0.1) - 10.000 Hz from the generator.</span></span></div></div><div data-block="true" data-editor="43910b" data-offset-key="eusoo-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="eusoo-0-0"><span data-offset-key="eusoo-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="eusoo-0-0"><span data-offset-key="eusoo-0-0"><span style="font-family: verdana;">For lower rates, like the ones on the x0.1 scale, the Ludlum should be placed on SLOW response mode to average and smooth out the reading - this will smooth out the pulse jitter from the needle. For the higher rates, FAST mode can be used just as well and the reading will be stable immediately.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="eusoo-0-0"><span data-offset-key="eusoo-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="eusoo-0-0"><span data-offset-key="eusoo-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-vAvNcdpPki8/YC8XVLc_JEI/AAAAAAAAObM/a0RITycVaCUtr1WVdMUHGeJn7DwB-9EbwCLcBGAsYHQ/s2048/20210217_162623.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1274" data-original-width="2048" src="https://1.bp.blogspot.com/-vAvNcdpPki8/YC8XVLc_JEI/AAAAAAAAObM/a0RITycVaCUtr1WVdMUHGeJn7DwB-9EbwCLcBGAsYHQ/s320/20210217_162623.jpg" width="320" /></a></div></span></div></div><div data-block="true" data-editor="43910b" data-offset-key="du2ns-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="du2ns-0-0"><span data-offset-key="du2ns-0-0"><span style="font-family: verdana;">Basically, it cost me nothing to put together this calibration setup - if I am to count the cost of the generator (which I already had) - it is still a "mere" $350 - not even 1/4 of the price of Ludlum 500 pulser. A Fluke 80K-40 probe for the High-Voltage measurements will add another $100.</span></span></div></div><div data-block="true" data-editor="43910b" data-offset-key="4h84u-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="4h84u-0-0"><span data-offset-key="4h84u-0-0"><span style="font-family: verdana;">The time-base of the generator has an excellent stability (1ppm) and it is many times more accurate than the Ludlum's voltage-to-frequency converter used in their circuit. In addition, pulse amplitude can be finely adjusted as well so one can align the counter's pre-amp sensitivity threshold.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="4h84u-0-0"><span data-offset-key="4h84u-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="4h84u-0-0"><span data-offset-key="4h84u-0-0"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-ocVcSVKOkr8/YC8XvvYADgI/AAAAAAAAObU/D_dQEy9HGNgS8K8s6Sv-S4WddC8sXfo_QCLcBGAsYHQ/s837/20210217_162933.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="837" data-original-width="572" height="320" src="https://1.bp.blogspot.com/-ocVcSVKOkr8/YC8XvvYADgI/AAAAAAAAObU/D_dQEy9HGNgS8K8s6Sv-S4WddC8sXfo_QCLcBGAsYHQ/s320/20210217_162933.jpg" /></a></div></span></div></div><div data-block="true" data-editor="43910b" data-offset-key="95nvc-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="95nvc-0-0"><span data-offset-key="95nvc-0-0"><span style="font-family: verdana;">This calibration method yields very accurate CPM rates and the reading can be adjusted with a pin-point precision on the scale.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="95nvc-0-0"><span data-offset-key="95nvc-0-0"><span style="font-family: verdana;"><br /></span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="95nvc-0-0"><span data-offset-key="95nvc-0-0"><span style="font-family: verdana;"><b>Disclaimer:</b> <u>This method will not be applicable for Dose rate calibrations</u> (the efficiency of the detector at certain gamma energies can not be measured without an actual calibrated activity gamma source) but it can be used to determine the calibration conversion constant for an instrument, already calibrated for the correct dose.</span></span></div></div><div data-block="true" data-editor="43910b" data-offset-key="3o0nt-0-0"><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="3o0nt-0-0"><span data-offset-key="3o0nt-0-0"><span style="font-family: verdana;">The generator just simulates a GM tube and each pulse produced will be correctly counted over time by the counter as the rate is known, fixed, and super-stable.</span></span></div><div class="public-DraftStyleDefault-block public-DraftStyleDefault-ltr" data-offset-key="3o0nt-0-0"><span data-offset-key="3o0nt-0-0"><span style="font-family: verdana;">The electronics are calibrated to ensure that the count rate is accurately displayed on the analog scale of the meter but how the detector generates pulses based on exposure to gamma rays or charged particles is not factored - it is assumed that each charged particle in the volume of the detector tube will be registered and will result in a pulse.</span></span></div></div></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com6tag:blogger.com,1999:blog-5557902467288736826.post-8512546633663370502020-12-09T23:40:00.020-05:002020-12-23T18:46:46.640-05:00Uranium van Gogh<p style="text-align: center;"><span style="font-family: verdana;"><b> </b>My favorite</span><span style="font-family: verdana;"> </span><span face="Roboto, Arial, sans-serif" style="background-color: #f9f9f9; color: #030303; font-size: 14px; text-align: left; white-space: pre-wrap;">☢️</span><span style="font-family: verdana;"> </span><span style="font-family: verdana;">specimen during an otherwise not-so-good year. This mineral exhibits awesome green crystals and it is named after one of the greatest female scientists.</span></p><p style="text-align: center;"><span style="font-family: verdana; font-size: medium;"><b>Cuprosklodowskite and Sklodowskite</b></span></p><p style="text-align: center;"></p><p style="text-align: center;"><span style="font-family: verdana;">Musonoi Mine, Kolwezi, Lualaba, Democratic Republic of the Congo</span></p><div style="text-align: center;"><a href="https://1.bp.blogspot.com/-bi1HZAI6iGI/X9GiAo3W5pI/AAAAAAAAN2g/KtH_GPq58e0tf7jVykVygDnAugeLOPvYQCLcBGAsYHQ/s1000/ysc1648g.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="778" data-original-width="1000" src="https://1.bp.blogspot.com/-bi1HZAI6iGI/X9GiAo3W5pI/AAAAAAAAN2g/KtH_GPq58e0tf7jVykVygDnAugeLOPvYQCLcBGAsYHQ/s320/ysc1648g.jpg" width="320" /></a></div><p style="text-align: center;"><span style="font-family: verdana;">"Sunflowers" (medium: Crystals on Matrix)<br /></span><span style="font-family: verdana;">If Uranium learned to paint from Vincent van Gogh - post-impressionism style...</span></p><div style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span> <a href="https://1.bp.blogspot.com/-Qa03a40FYsU/X9Gh_gGtTiI/AAAAAAAAN2I/Sg92OeSM8ZgJOliol5iaCkqzcD_LMSOMgCLcBGAsYHQ/s1000/ysc1648a.jpeg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="750" data-original-width="1000" src="https://1.bp.blogspot.com/-Qa03a40FYsU/X9Gh_gGtTiI/AAAAAAAAN2I/Sg92OeSM8ZgJOliol5iaCkqzcD_LMSOMgCLcBGAsYHQ/s320/ysc1648a.jpeg" width="320" /><br /></a><span style="font-family: verdana;"><span style="text-align: left;">A gorgeous specimen, with two main cavities, 15 mm across, richly lined with luminous green Cuprosklodowskite, turning to yellow Sklodowskite closer to the Uraninite matrix.</span></span></div><div style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span><a href="https://1.bp.blogspot.com/-0rFTAt6X-eA/X9Gh_rcMlqI/AAAAAAAAN2M/Kbp4M1aFA-4ubzRb-PNPlWnd9eNcBEe9gCLcBGAsYHQ/s1000/ysc1648b.jpeg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="865" data-original-width="1000" src="https://1.bp.blogspot.com/-0rFTAt6X-eA/X9Gh_rcMlqI/AAAAAAAAN2M/Kbp4M1aFA-4ubzRb-PNPlWnd9eNcBEe9gCLcBGAsYHQ/s320/ysc1648b.jpeg" width="320" /></a><br /></div><div style="text-align: center;"><span style="font-family: verdana;">Size is 2.8 × 4.9 × 3.5 cm with largest crystals around 5mm</span></div><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-JSDZ00s8vJo/X9Gh_vQtJKI/AAAAAAAAN2Q/UN3ZhAfSSLoAUscLx1q1Ojpw5CairXCkACLcBGAsYHQ/s1000/ysc1648c.jpeg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="901" data-original-width="1000" src="https://1.bp.blogspot.com/-JSDZ00s8vJo/X9Gh_vQtJKI/AAAAAAAAN2Q/UN3ZhAfSSLoAUscLx1q1Ojpw5CairXCkACLcBGAsYHQ/s320/ysc1648c.jpeg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The rock, I affectionally call "Marie" is quite "hot" - at 1" (2.54cm) it measures over 508 000 CPM with my LND7317-based counter (if I have the "dead time" GM tube constant set correctly). This is approximately 145 mR/hr or 1.45 mSv/hr! </span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">I noticed a direct correlations between the "looks" of a specimen and its activity when it comes to Uranium minerals - the prettiest looking ones are usually also the most active :-)</span></div><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-54ZzrP_nFsM/X9Gh_xqn5HI/AAAAAAAAN2Y/YN_i4U5MGLI5xe61BCcgcgJ8Om7ca61-gCLcBGAsYHQ/s1000/ysc1648d.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="802" data-original-width="1000" src="https://1.bp.blogspot.com/-54ZzrP_nFsM/X9Gh_xqn5HI/AAAAAAAAN2Y/YN_i4U5MGLI5xe61BCcgcgJ8Om7ca61-gCLcBGAsYHQ/s320/ysc1648d.jpg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Crystal tufts of Sklodowskite (Mg(UO<span style="font-size: xx-small;">2</span>)<span style="font-size: xx-small;">2</span>(HSiO<span style="font-size: xx-small;">4</span>)<span style="font-size: xx-small;">2</span>·5(H<span style="font-size: xx-small;">2</span>O)) stem from the Uraninite infused matrix and transition into Cuprosklodowskite (Cu(UO<span style="font-size: xx-small;">2</span>)<span style="font-size: xx-small;">2</span>(HSiO<span style="font-size: xx-small;">4</span>)<span style="font-size: xx-small;">2</span>·6(H<span style="font-size: xx-small;">2</span>O))</span></div><div class="separator" style="clear: both; text-align: center;"><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-FhoZ8IPB5VM/X9GiAe7q3VI/AAAAAAAAN2U/vbBkuhgNJW0-1-wn7xuT63SQAnJy-DzcACLcBGAsYHQ/s1000/ysc1648e.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="834" data-original-width="1000" src="https://1.bp.blogspot.com/-FhoZ8IPB5VM/X9GiAe7q3VI/AAAAAAAAN2U/vbBkuhgNJW0-1-wn7xuT63SQAnJy-DzcACLcBGAsYHQ/s320/ysc1648e.jpg" width="320" /></a></div></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">One of the two cavities densely populated with crystals.</span></div><div class="separator" style="clear: both; text-align: center;"><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-h5KcDX7PAkI/X9GiAo-WZgI/AAAAAAAAN2c/MOD9G4yALZ43f7UX9rzA1k6AdpwzgEG8QCLcBGAsYHQ/s1000/ysc1648f.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="814" data-original-width="1000" src="https://1.bp.blogspot.com/-h5KcDX7PAkI/X9GiAo-WZgI/AAAAAAAAN2c/MOD9G4yALZ43f7UX9rzA1k6AdpwzgEG8QCLcBGAsYHQ/s320/ysc1648f.jpg" width="320" /></a></div></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Activity for this mineral is quite high - Sklodowskite has a calculated activity of 99.244 KBq/gram and exposure of 1.38 mRem/hr for 1 gram when held in hand. Considering that it also contains Uraninite with even higher activity it is definitely one of the specimen requiring caution when handling and storage.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">2.4 kg pure Sklodowskite specimen will give you the 3.6 R/hr exposure - "not great, not terrible"</span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-ZCfCCCtBF54/X9eIK_MO1ZI/AAAAAAAAN5o/XZhEtuX6Qo4TnZXkcxe-YBqr5f44-gKpgCLcBGAsYHQ/s1080/Cuprosklodowskite.jpeg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1080" data-original-width="1080" height="320" src="https://1.bp.blogspot.com/-ZCfCCCtBF54/X9eIK_MO1ZI/AAAAAAAAN5o/XZhEtuX6Qo4TnZXkcxe-YBqr5f44-gKpgCLcBGAsYHQ/s320/Cuprosklodowskite.jpeg" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Earth Archives card about the Cuprosklodowskite.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-696CeDzWJBk/X9eZNEImZ3I/AAAAAAAAN50/GfnAo7oD4lgd35ZJzZTf0Lh_c9XYfcz6gCLcBGAsYHQ/s2048/IMG_8725.JPG" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1386" data-original-width="2048" src="https://1.bp.blogspot.com/-696CeDzWJBk/X9eZNEImZ3I/AAAAAAAAN50/GfnAo7oD4lgd35ZJzZTf0Lh_c9XYfcz6gCLcBGAsYHQ/s320/IMG_8725.JPG" width="320" /></a></div><span style="font-family: verdana;"> Another Cuprosklodowskite from the same locality - </span><span style="text-align: left;"><span style="font-family: verdana;">Musonoi Mine, Kolwezi, Lualaba, Democratic Republic of the Congo</span></span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">The specimen exhibits interweave of shiny, glassy bright-green "sturdy" acicular crystals of Cuprosklodowskite.<br /></span><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-yZ5s3cHytno/X9eaDj1xdQI/AAAAAAAAN58/sDyjxepP_Lc0sX6eTw-WJIq42JycAdBBQCLcBGAsYHQ/s2048/IMG_8718.JPG" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1970" data-original-width="2048" src="https://1.bp.blogspot.com/-yZ5s3cHytno/X9eaDj1xdQI/AAAAAAAAN58/sDyjxepP_Lc0sX6eTw-WJIq42JycAdBBQCLcBGAsYHQ/s320/IMG_8718.JPG" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">Yet another Cuprosklodowskite and Uraninite. Same locality as the other above.</span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;">This specimen has a</span><span style="text-align: left;"><span style="font-family: verdana;"> bright green area of microcrystals and a black uraninite crude crystal on a base of gummite matrix.</span></span></div><div class="separator" style="clear: both; text-align: center;"><span style="text-align: left;"><span style="font-family: verdana;">Cuprosklodowskite in general is a very active mineral and the Uraninite crystal just adds to this - measured activity is around 150 000 CPM @ 5 mm.</span></span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><img border="0" src="https://1.bp.blogspot.com/-sdqcwrnp6_M/X9fFYm-g4mI/AAAAAAAAN6o/jgMalbWLoNcAvm1iLTwywz6FdNRDNHGjQCLcBGAsYHQ/s320/Mineral_colllection_logo3.jpg" /></div><div class="separator" style="clear: both; text-align: center;"><br /></div>Andrey E. Stoevhttp://www.blogger.com/profile/12033396081050348304noreply@blogger.com0