Notes on Geiger Counters

Summary

BlogOccasional updates about Divested projects and other fun from Tavi.Sundry updates are now on the Roll page.The text on this page is licensed CC BY-SA 4.0 unless stated otherwise.Notes on Geiger Counters¶2025-09-24DisclaimerI am just some random software developer. I have no actual experience in this field. This information is purely for other hobbyists. I'm also not going to provide detailed explanations about their use or about radiation itself, there are more knowledgeable people who have written in depth about that. If you work around radiation in any professional manner, your workplace almost certainly already provides you with the necessary training and proper equipment. Absolutely never place your life in the hands of these cheap toys.PrefaceI have always wanted a geiger counter since I was young. It popped up every few years but they were always pricey and/or rough. I've recently been watching through The X-Files which occasionally shows them and there was also recently a thread on the front page of HN about a DIY counter using a Flipper. So I started looking into options again.Extremely Basic Overview of RadiationIn this context of ionizing radiation, there are five types: neutron, alpha (α), beta (β), gamma (γ), and X-rays.They are emitted during the decay process of an atomic nucleus.Neutron, alpha, and beta radiation are classed as particle radiation.X-rays and gamma radiation are classed as electromagnetic radiation (photons). Although they are produced differently, X-rays are formed from electrical acceleration whereas gamma is a nuclear process.Different decay chains emit more of each type than others.Different emissions also have varying levels of energy per photon, usually measured in electronvolts.Alpha radiation is easily stopped by extremely thin materials such as paper or the very outer layer of your skin.Beta radiation can be stopped by thin metal.Gamma radiation however requires dense materials such as concrete or lead to be stopped.Lastly ...