Hi all,
I'm the "Better Geiger" guy, creator of the product CJ was using down there (
www.bettergeiger.com ). We had more communication than the average customer because of some shipping complications (some combination of USPS/covid/brexit has caused a lot of trouble with my shipments to the UK, but that's a different topic).
From a quick scan through this thread I wanted to add two things -
1. As CJ mentioned at the start the detector is sensitive to beta, but the efficiency is very low so in practice unless you are very close to a fairly strong beta emitter the dose value you read will generally just be from gamma. So extra beta shielding under normal circumstances is not needed, but if you are measuring a specific object you could put a little aluminum between and check how that affects the count rate to see how much of the count rate is coming from beta.
2. As someone mentioned, alphas are 20x more damaging to cells than X-ray/gamma/beta. That's only part of the story, though, external alpha will generally be of little to no harm because the energy is deposited in your skin which is very insensitive to radiation (in fact it will usually not even reach there, as clothing will block alpha). However, when inhaled or ingested an alpha emitter can deposit energy directly into lungs and other organs, that's where the 20x factor comes into place. There are correction factors for whole-body exposure (usually relevant to X-ray/gamma) vs. if an exposure is entirely to one specific organ (like skin or eyes, or in medical situations when you get an X-ray to a specific body part, etc.). The story gets complicated quickly.
For you all though, as I think you are all well aware, radon is the main concern most of the time, which is of course an issue because it is gaseous and being inhaled.
I gave a lot of more general information over here on reddit recently, I'm drafting more thorough general info for my web site, feel free to take a look although I forgot to talk about radon there because that post was aimed specifically at the prepping community which was an unexpectedly large part of my customer base:
If you have any questions for me feel free to ask, but if I forget to check back here then send them via my web site.
Stay safe down there!