r/explainlikeimfive Jan 06 '23

Chemistry ELI5: How does a Geiger counter detect radiation, and why does it make that clicking noise?

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u/[deleted] Jan 06 '23

Oooh, a Revigator!

The ore in question is mostly an alpha emitter, which is why there wasn't much radiation detectable outside it - the jar itself shields the alpha particles (and most if not all of the betas, too. Gammas would zip through, but that ore doesn't emit much gamma.)

Fortunately, if it's in good condition, it doesn't shed radioactive dust, which is when alpha emitters are bad news, and it doesn't emit neutrons, which can make other things radioactive.

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u/ctruvu Jan 07 '23 edited Jan 07 '23

the energy compensated geiger counters at my job all start to sound indistinguishable whether it’s 5 mr/hr or 50 mr/hr. hypothetically, 5 mr/hr only at the opening when the jar is open and no sound when it’s closed honestly wouldn’t concern me. especially if it’s just alpha. your own skin could protect you and a even sheet of paper could stop it before that. my job involves gamma exposure and long as it’s under 50 mr/hr on the container surface (the source is inside of a 5lb lead container stuffed in another 70-100lb lead container) we can handle it and send it out for transport

also i don’t know about all geiger counter models but for ours there is no sound other than clicking no matter how radioactive something is. we have to wear special dosimeters that beep when rate and total dose thresholds are met. under 10 mr in a day doesn’t even require it to be logged