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 2.GQ Geiger Muller Counter
 Sensitivity of 320plus to xray
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F_Schro

USA
4 Posts

Posted - 11/09/2015 :  14:45:55  Show Profile  Reply with Quote
Trying to determine/compare sensitivity to soft xrays. Using a Victoreen 493 and the GMC-320plus and a high vacuum glass bottle with 1/2" tungsten rod's spaced about 1/16"

KVDC____493______________320plus
19_______0.35-0.34mr/Hr____0.037-0.039mr/Hr
22_______30-40mr/Hr________0.32-0.37mr/Hr


The GMC seems to be about 1/10th as sensitive as the 493.

If anyone has any ideas on this method or a better way please chime in.
Reply #1

ZLM

1261 Posts

Posted - 11/09/2015 :  22:01:51  Show Profile  Reply with Quote
This should be a calibration related. Not the sensitivities.

If you think the reading on KVDC-493 is correct reading, then change the GMC-320 calibration data to followings will get the same reading as your KVDC-493:


From GMC-320 main menu, select Init-Setup then Calibrate, you should see Calibrate 1, 2, 3.

on Calibrate 1, change the CPM from 60 to 6

on Calibrate 2, change the CPM from 240 to 24

on Calibrate 3, change the CPM from 1000 to 100
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Reply #2

F_Schro

USA
4 Posts

Posted - 11/10/2015 :  09:43:26  Show Profile  Reply with Quote
My application is in detection of "possible" xray output of a high voltage/high vacuum device at various test voltages.

So calibration is less important to me then will the GMC320 detect these energies.

My problem is; The GMC detects fine if it's placed very close the the generator but my test calls for the GM tube to be placed 3FT from the source.

Sorry, did I post this question in the wrong forum ?

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Reply #3

Distelzombie

Germany
202 Posts

Posted - 11/10/2015 :  21:30:45  Show Profile  Reply with Quote
Regarding the almost same size of the detectors, I would say the X-Rays aren't of a high enough energy to be detected by the M4011 tube of the 320.

But I'm no scientist nor a native English speaker, so , don't take whatever you read for granted. :D

You could try to open the casing and measure again, with the tube facing the source. This makes a almost 10 times increase in Beta-Ray detection, so maybe that helps.
Don't know why the engineers had build it that sealed though. It seems rather stupid. Sry guys. :P

GMC-300E+ V4.20 with sbt-11a alpha tube

My statements are "stuff-a-hobbyist-says" and not in any way professional.

Edited by - Distelzombie on 11/10/2015 21:47:38
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Reply #4

F_Schro

USA
4 Posts

Posted - 11/16/2015 :  14:00:55  Show Profile  Reply with Quote
Well I would have checked without the case but the manufacture was nice enough to accept a return if it was not sensitive enough for my application so I didn't crack it open.

But compared to my old Victoreen it was about 1/10th as sensitive to whatever energies this source has.

My voltage levels are less than 30KVDC and the contacts are round rod shaped with no angle on the anode.

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Reply #5

Distelzombie

Germany
202 Posts

Posted - 11/16/2015 :  17:17:36  Show Profile  Reply with Quote
Ok. But you don't need to "crack" it open. It has screws.
And why Voltage? I see nobody talking about voltage, only model numbers. But maybe I'm just confused. :)

GMC-300E+ V4.20 with sbt-11a alpha tube

My statements are "stuff-a-hobbyist-says" and not in any way professional.
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