Homemade GM tube

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Antonio Zanardo
Posts: 5
Joined: Tue Feb 27, 2018 8:48 am

Homemade GM tube

Postby Antonio Zanardo » Tue Mar 06, 2018 8:54 am

Hi Jeff,

I hope you can give me a good advice once more.

I am using GM tubes as sensors to detect cosmic rays.
Recently I had the chance to cut up one of them and have seen their simple design.

Thus I began to make one sample by myself. Since then I made various pieces, changing each time tube material, shape and dimensions, filling gas mixtures and pressure, and of course the high voltage levels.

In no cases I was able to get them working.

A bit at a time I realized that those devices are not as simple as they appear to be. The commercial products possibly use noble and quenching gas at very strict percent and exact pressure. In my tests I used Argon and propane in various proportions and went down to 30 mm Hg. pressure, but I don’t know if they are the the right ones. Unfortunately there is no detailed literature on the web about those features, thus my tests are based on the trial and error process.

A Japanese guy says he made a Geiger sensor out of a film canister, a sheet of paper as cathode(?!) and few other things. It allegedly works on an air-propane mixture at atmospheric pressure.
On the contrary, I made my detectors much like a commercial GM tube, but nevertheless they don’t work.

Do you have a detailed knowledge on how a GM tube is made, especially with respect to the kind of gas mixture and its percent, and the level of its pressure?

Anyway, is there anybody in this group who made a GM tube and is willing to share his experience with me ?

Thank you so much.

Antonio Zanardo

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mightyohm
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Location: Seattle, WA
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Re: Homemade GM tube

Postby mightyohm » Tue Mar 06, 2018 9:59 am

What voltage are you biasing the tubes with? You may find that your DIY tubes require a higher voltage than the commercial tubes.

There are some details on the construction of geiger counter tubes in Knoll's book
https://phyusdb.files.wordpress.com/201 ... yknoll.pdf
starting at page 202.

Here's another article that might be interesting to you: https://archive.li/lolVB#selection-659.78-661.35

Antonio Zanardo
Posts: 5
Joined: Tue Feb 27, 2018 8:48 am

Re: Homemade GM tube

Postby Antonio Zanardo » Tue Mar 06, 2018 12:10 pm

Jeff,

I made a variable voltage that can be set anywhere from 450V to 5KV. I always test my different home made GM at variuos voltage.

Thank you for the first link. I took a look at it, and found , among other interesting things, that the fill gas must not be contaminated , specially by oxigen.This fact could have caused my failures. Next time I test a tube, Ill' make absolutely sure to fill the tube with non contaminated gas.

As for the second link, It would be nice to get in touch with that nuke specialist. I don't know if I can mention him by name here. He would surely be able to solve all my GM tube problems.

Any hint on how to contact him, please?

Thank you for your help.

Antonio Zanardo

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mightyohm
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Posts: 974
Joined: Fri Apr 03, 2009 10:29 pm
Location: Seattle, WA
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Re: Homemade GM tube

Postby mightyohm » Wed Mar 07, 2018 11:26 am

Sorry, I don't know the author. I found the page using google search.


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