Steven,
I like the results you got!
And I think this is about as good as it gets, this counter is only designed for... well, counting. You can discriminate alphas and betas, and detect both with an incredible efficiency.
If you want it to be spectroscopic you need to work with gas with additives, different techniques like a frisch grid, and especially more pressure to stop anything beyond alphas.
Also, readoud should be done in <500 ns, because the electron drift is very quick and ions can be ignored here, your µs long readout will strongly reduce the resolution as ions recombine in this time and skew the actual charge you're getting.
This is the simplest-possible proportional counter one can build, and I think the results are impressive for what it is, but it isn't much.
Lukas
First attempt at building an alpha beta detector
-
GigaBecquerel
- Posts: 172
- Joined: 04 Jul 2020, 07:34
-
Sesselmann
- Posts: 1398
- Joined: 27 Apr 2015, 11:40
Re: First attempt at building an alpha beta detector
Lukas,
How do I discriminate between alpha and beta when the source is placed inside the chamber ?
Steven
How do I discriminate between alpha and beta when the source is placed inside the chamber ?
Steven
-
GigaBecquerel
- Posts: 172
- Joined: 04 Jul 2020, 07:34
Re: First attempt at building an alpha beta detector
Just by amplitude.
An alpha will be stopped completely in the detector and deposits a few MeV, while a beta will only deposit a fraction of its few keV to MeV.
If you have a simple ratemeter like a Model 12 or similar you can put an alpha source in the detector and slowly raise the voltag until you get a constant count rate from that, you should see a plateau like I demonstrated here:
https://www.gammaspectacular.com/phpBB3 ... f=14&t=914
If you are in the alpha plateau you can be pretty sure that the detector won't see betas, but you can double check by putting a beta source in it. If you have only betas inside the detector and raise the voltage you will get another plateau at a higher voltage than the alpha plateau, at which you will count alpha and beta.
Substracting the count rate at the alpha plateau from the rate at the beta plateau will give you beta countrate
An alpha will be stopped completely in the detector and deposits a few MeV, while a beta will only deposit a fraction of its few keV to MeV.
If you have a simple ratemeter like a Model 12 or similar you can put an alpha source in the detector and slowly raise the voltag until you get a constant count rate from that, you should see a plateau like I demonstrated here:
https://www.gammaspectacular.com/phpBB3 ... f=14&t=914
If you are in the alpha plateau you can be pretty sure that the detector won't see betas, but you can double check by putting a beta source in it. If you have only betas inside the detector and raise the voltage you will get another plateau at a higher voltage than the alpha plateau, at which you will count alpha and beta.
Substracting the count rate at the alpha plateau from the rate at the beta plateau will give you beta countrate
