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 2.GQ Geiger Muller Counter
 GMC500+ problem or real event happening
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Phildel

Australia
5 Posts

Posted - 07/12/2020 :  05:07:54  Show Profile  Reply with Quote
I report to maps every 5mins and log every 1min. I take the 1min data and produce an average monthly graph. The graph started at 30cpm and is now at 50cpm over 18 months with clear rate changes for my winter in Melbourne Australia. Any ideas, 500+ or environmental. The unit sits on a desk facing north but not in direct sunlight.


Phil
Reply #1

Damien68

France
241 Posts

Posted - 07/12/2020 :  05:22:20  Show Profile  Reply with Quote
itís more like a natural phenomenon,
if your device is near a wall there may be radon infiltration in this wall which can vary over time. at my house i have stuff like that in same rate.
if this is the case you can move the device away from the wall by 1 meters for 2 or 3 hours and see if the CPM rate decreases.

Note: the first radon decay is not detectable by GMC-500+ (alpha emission) but the 3rd and 4th decay are detectable

you can also leave your home with your meter and go more than 10 meters away from all construction and see what it gives.

Mastery is acquired by studying, with it everything becomes simple

Edited by - Damien68 on 07/12/2020 05:37:39
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Reply #2

Phildel

Australia
5 Posts

Posted - 07/12/2020 :  05:29:57  Show Profile  Reply with Quote
[quote]Originally posted by Damien68

itís more like a natural phenomenon,
if your device is near a wall there may be radon infiltration in this wall which can vary over time. at my house i have stuff like that in same rate.
if this is the case you can move the device away from the wall by 1 meters and see if the CPM rate decreases.
[ok I'll move it and see what happens after a week]

Phil
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Reply #3

Damien68

France
241 Posts

Posted - 07/13/2020 :  00:04:35  Show Profile  Reply with Quote
I just saw your log on gmcmap near Melbourne,
the data stays high

Mastery is acquired by studying, with it everything becomes simple
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Reply #4

Phildel

Australia
5 Posts

Posted - 07/13/2020 :  18:17:51  Show Profile  Reply with Quote
Originally posted by Damien68[/i]

I just saw your log on gmcmap near Melbourne,
the data stays high
[Just did the 1min CPM average for July and its dropped for the first time in 18mth to 50CPM average month to date about to relocate it (next couple of days) to a new site to see what happens]

Phil
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Reply #5

Damien68

France
241 Posts

Posted - 07/22/2020 :  07:00:17  Show Profile  Reply with Quote
the best way to do it would be to have 2 counters if possible of different brand to confirm or not the measurements.

Mastery is acquired by studying, with it everything becomes simple
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Reply #6

ullix

Germany
491 Posts

Posted - 07/30/2020 :  02:08:00  Show Profile  Reply with Quote
There are quite a few reports currently in discussion showing strange data - as in this report - or mysterious spikes in the readings.

I suggest to verify that the anode voltage is in the proper range, and not near the edge and perhaps drifting.

Also, I have seen more than once an impact of light on the tubes, strangely even with the blackened ones. So make a run with the Geiger counter put in a light tight box and compare over a full day.
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