Hi,
your project is very interesting and original, nice to see something like this after so many other projects have already been launched within Boinc.
Let me ask two questions (I haven't found answers here):
1. You claim your G-M detector (CTC-5) is able to detect gamma radiation only. However, G-M tubes are usually able to detect alpha, beta and gamma radiation. Why this difference please?
2. Since radon decays primarily through emitting an alpha particle, does this mean that your detector is not able to measure radon levels? Radon is the primary source of radiation in buildings, it would be very useful if your detector could detect it.
Thanks for you answers, I keep my fingers crossed.
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Both STS-5 and SBM-20 are shielded - the tube is made from metal.
It surely stops most (if not all) of the alpha radiation - tubes used to detect alpha usually have small window which is transparent for alpha radiation.
STS-5 detects beta, perhaps the shield stops some of the particles but definitely not all.
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There should be tube with a window made from mica to detect alpha radiation because mica is almost transparent for alpha rays. STS-5 (CTC-5) has thin metal shield and thus detects beta and gamma.
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There would be a mica window (very very thin and fragile) to let alpha and beta particles through.
Alpha particles can only travel a few inches at most through air so you would have to be pretty much right on top of the emitter to detect them. They can also be stopped by a sheet of paper.
Beta can travel several feet through air, however are stopped by thin layers of metal or plastic, so the metal shield would probably stop them. If you had your project in any sort of case, that would probably stop the detection as well.
Gamma and I would assume X rays, are similar and of course easily can go through the case of the detector and be noticed.
Its probably not that the detector can't detect them, but more a case of, the particles can't get to it TO be detected.
Aaron
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The shield on the SBM-20/STS-5 does not completely absorb beta, not even in my plastic case (it's front and bottom are 3mm thick plastic, sides 2mm).
There is another version of the tube - SBM-20-1, with shield made from 5-6 layers of tin or lead foil (grounded). This tube almost completely ignores alpha and beta radiation. The one on photo below was used in russian dosimeter, I forgot the exact model (I bought the tube from auction) but it was gamma only detector.
The difference is huge, with alpha/beta source placed directly at the tube SBM-20 reads ~2.5µSv while the shielded version barely notices any change.
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There should be tube with a window made from mica to detect alpha radiation because mica is almost transparent for alpha rays. STS-5 (CTC-5) has thin metal shield and thus detects beta and gamma.
I want to be able to detect gamma. If I find a tube with a mica window and it is rated to work at 400 volts:
1) will that tube work with your detector?
2) would that tube require a change to the firmware in order to work properly?
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It will work without any changes.
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