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 GMC 320 Plus vs X-ray tube with Mo anode
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Petrovski

Netherlands
14 Posts

Posted - 05/27/2016 :  13:17:37  Show Profile  Reply with Quote
Tube power was set to 60kV and 50mA. Energy of the K-alpha is around 18 keV. Source was about one meter away from the 320+. I noticed that the radiation was detected instantly after opening the tube shutter, and stabilized around 5000 CPM after 30 seconds. It took the 320+ a while (over a minute) to cool down and detection levels returned to background.

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Sorry no intensity graph, forgot to set the logger function to take a sample every second.
Reply #1

ZLM

1068 Posts

Posted - 05/27/2016 :  22:45:05  Show Profile  Reply with Quote
Great!
Can you provide detailed information on how you did that?
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Reply #2

Petrovski

Netherlands
14 Posts

Posted - 05/29/2016 :  09:37:41  Show Profile  Reply with Quote
Well, it's simply lying at the bottom of the enclosure of an X-ray diffractometer (at my work). I can choose between multiple X-ray tube anode materials, and can control the HT generator's power.

I'll repeat this test with data logging set to 1 second interval, I'm sure it will produce an interesting graph.
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Reply #3

Petrovski

Netherlands
14 Posts

Posted - 05/30/2016 :  08:24:02  Show Profile  Reply with Quote
Today I've repeated the test. I've put the 320-Plus on a sample stage so it was now ~10 cm away from the X-ray tube's aperture:

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I started again with the tube at max power (60kV/50mA) but as soon as I opened the shutter the 320-Plus saturated and the firmware rebooted.

So I lowered the power to 15/5 and checked the 320-Plus's response while I slowly increased the power. At 40/20 it was well in the 30k CPM range:

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The logged data does not reflect the experiment however. The max CPM on display is not logged, and also it does not show the increase of CPM while I increased the tube power:


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If I had to guess, it seems the firmware was too busy detecting radiation and the data logger task got low priority. Perhaps someone from GQ can confirm this?

Update: actually on a logarithmic scale you can see the first power ramp-up. But after that, none:

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Edited by - Petrovski on 05/30/2016 09:08:57
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Reply #4

Distelzombie

Germany
188 Posts

Posted - 06/01/2016 :  12:50:58  Show Profile  Reply with Quote
Could it be affected by some electromagnetic radiation? (it can be, I tested it)

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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Reply #5

ZLM

1068 Posts

Posted - 06/01/2016 :  23:46:40  Show Profile  Reply with Quote

Petrovski: What is your GMC-320 firmware version? The latest version should take care the task priority between counting ,data logging and display task. The counting task always be a highest priority task.
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Reply #6

Petrovski

Netherlands
14 Posts

Posted - 06/02/2016 :  11:11:04  Show Profile  Reply with Quote
@ Distelzombie: you mean like EMC interference? Could be, but since it's in an radiation tight enclosure I'm pretty sure it's just X-rays and the GMC itself in there.

@ ZLM: I have revision 4.12.
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Reply #7

Distelzombie

Germany
188 Posts

Posted - 06/06/2016 :  12:33:38  Show Profile  Reply with Quote
Try to build a faraday cage. I once made one that worked great using a sieve and some cardboard with aluminum foil around.

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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Reply #8

Petrovski

Netherlands
14 Posts

Posted - 06/07/2016 :  10:58:59  Show Profile  Reply with Quote
First I'll try the experiment again with new firmware. I've sent an email to GQ customer support.
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