<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body dir="auto"><div dir="auto">Have passed the query on to an acquaintance who works with radioactive materials. No guarantee I'll get a reply, of course.</div><div dir="auto"><br></div><div dir="auto">Peter</div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div id="composer_signature" dir="auto"><div style="font-size:12px;color:#575757" dir="auto">Sent from my Galaxy</div></div><div dir="auto"><br></div><div><br></div><div align="left" dir="auto" style="font-size:100%;color:#000000"><div>-------- Original message --------</div><div>From: Rhys Sage via Swlug <swlug@mailman.lug.org.uk> </div><div>Date: 06/03/2025 16:34 (GMT+00:00) </div><div>To: South Wales Linux User Group <swlug@mailman.lug.org.uk> </div><div>Cc: Rhys Sage <rhys_sage@yahoo.com> </div><div>Subject: [Swlug] DIY Geiger counter </div><div><br></div></div>I'm in the middle of a project - to build a Geiger counter. It's a fun project so far.<br><br>I have all the bits I need (I think) but as with all projects there's a lot of experimentation and changes made on the fly. <br><br>I'm using a Thalium-doped Cesium Iodide crystal in combination with a BPX61 photo diode. For those that don't know- the BPX61 is slightly more sensitive to green light. The crystal emits blue/green light when struck by gamma radiation. Whether it emits light when struck by Alpha, Beta or X-Ray, I don't know. I do know there are other crystals more suited to those.<br><br>The BPX61 output will feed into an OPA134PA amplifier and then that will in turn feed into a microcontroller. Given that the events generated by radioactive decay are very brief, would microcontroller speed make much difference? I could use an ATTiny13/ATTiny85 or something small like a micro RP2040 or an ESP32 C3 Super Mini.<br><br>With a regular Geiger counter,does the system store the events somehow or does it just rely upon measuring maximum pulses when a pulse happens during a sampling period?<br><br>Rhys Sage<br><br>-- <br>Swlug mailing list<br>Swlug@mailman.lug.org.uk<br>https://mailman.lug.org.uk/mailman/listinfo/swlug<br></body></html>