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 2.GQ Geiger Muller Counter
 GMC080 cover tests
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atomic.dave

USA
65 Posts

Posted - 10/03/2011 :  15:34:32  Show Profile  Reply with Quote
Has anyone tried to test the difference of sensitivity when the cover is on or off their GMC080? try it and you will see a MAJOR difference in sensitivity especially with the M4011 tube. Here are some test result averages over 5 minutes with and without the cover at the same distance from the tube: I am using GeigerBot and a data cable to my iphone.

Uranium Bead - on- 50, off- 300
Thorium Mantle - on- 200, off- 900
Americium Pellet - on- 400, off- 500

Background radiation in my area of California, i showed:
With cover- 17
Without cover- 19

I'm planning on drilling some vent holes thru the cover and will run more tests.

to be continued...

Edited by - atomic.dave on 10/03/2011 17:56:54
Reply #1

Odiez1

73 Posts

Posted - 10/04/2011 :  12:32:30  Show Profile  Reply with Quote
I'm sure that having the cover on will effect the counts. It's another layer of substance to stop the rays from getting to the anode of the tube.
I just leave the M4011 tube attached by the clips, soldered to wires, soldered to the board. That way when I want more sensitivity I just pull it out and it hangs by the wires.

I had an interesting time at a local kitchen/bath supply store. Found a few types of granite counter top samples showing ~50CPM. Seems the darker granite with the reflective spots were 'hotter' than the lighter colored ones. BTW, the sales associate was pleased as punch to have me checking things for her.

Anyway.. I noticed fewer counts when the M4011 was inside the box, than when it was out..

Let me know how the rad holes work out. :)

-Odie
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Reply #2

ZLM

1261 Posts

Posted - 10/05/2011 :  08:46:24  Show Profile  Reply with Quote
The cover on and cover off will be a little different. Only high sensitivity tube can detect those differences.
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