Can a geiger counter be used to measure milk?

Submitted by Anonymous on Tue, 2011-04-05 18:02

If we don't need to know which radionuclides, is a typical consumer geiger counter that measures alpha beta and gamma radiation sufficient to determine whether a food or milk has increased levels of radioactivity? Here is a typical sensitivity profile

Detects alpha down to 2.5 MeV; efficiency at 3.6 MeV > 80%
Detects beta at 50 keV w/35% efficiency, at 150 keV w/75%
Detects gamma and X rays down to 10 keV thru window, 40 keV minimum through case; gamma sensitivity is 1,000 CPM/mR/hr

Thank you for anyone from the team who may have some insight into this.

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Short answer: no. "Gamma

Submitted by Brian (not verified) on Tue, 2011-04-05 18:11.

Short answer: no.

"Gamma sensitivity is 1000 CPM/mR/hr". Natural background is something like 20 uR per hour depending on where you stand. This gives a supposed sensitivity of 20 CPM, which you won't achieve anyway because of statistical fluctuations in the number of counts. Also, the radiation we see is on the order of 1 CPM at the most.

Brian [BRAWM team member]

Good question

Submitted by Anonymous (not verified) on Tue, 2011-04-05 22:39.

Brian, first, I want to say that I am very appreciative of you taking the time to answer my post. I just wanted to clarify what I think you were saying:

If I have a geiger counter that detects 0 - 50,000 CPM (I posted the exact stats below). Then it will detect radiation in milk (e.g., photon emission - or is it weaker than 10keV from what you were finding?). However, because the radiation your team is detecting in milk is at 1 CPM max, there would be no way for me to distinguish radiation from milk from background radiation at 20 CPM.

However, if I were to take a lead apron and wrap it around a box, and then put the detector and a glass of milk in there, then I would be able to detect radiation in milk since I will get a click every time a photon hits the counter. Is that correct?

Here are the manufacturer specs:

"Halogen-quenched uncompensated GM tube Thin mica window is 1.5-2.0 mg/cm2 thick. Approx. 1000
CPM/mR/hr for Cesium 137.

Detects alpha down to 2.5 MeV; typical detection efficiency at 3.6 MeV is greater than 80%.
Detects beta at 50 keV with typical 35% detection efficiency.
Detects beta at 150 keV with typica 75% detection efficiency.
Detects gamma and x-rays down to 10 keV typical
through the window, 40 keV minimum through the
case. (GRAPH 1). Normal background is 5-20 CPM."

Is the 1000 CPM the upper or

Submitted by Anonymous (not verified) on Tue, 2011-04-05 18:20.

Is the 1000 CPM the upper or lower bound?