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 2.GQ Geiger Muller Counter
 Average medical x-ray
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n8xyn

USA
52 Posts

Posted - 05/17/2018 :  15:47:52  Show Profile  Reply with Quote
I just tried the at home generation of x-rays using an old RCA vacuum tube with a wide space between the two electrodes. I ran it for a couple short bursts and sent my gmc-500+ to 2740 cpm before I killed it out of fear. Has anyone here actually measured a standard medical x-ray before? I really don't want to do that again as I was all of 2 or 3 feet from the tube. A couple times I knocked a computer monitor off line that was 10 feet away....

Jim Whitaker
Reply #1

ullix

Germany
213 Posts

Posted - 05/17/2018 :  23:43:13  Show Profile  Reply with Quote
What was the voltage at the tube?

This knocking a computer monitor offline sounds more like electrical interference, which could have impacted the counter as well.
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Reply #2

EmfDev

106 Posts

Posted - 05/18/2018 :  08:47:34  Show Profile  Reply with Quote
I just asked my friend he put the GMC-320 in his pocket when he did an x-ray for his upper body.
But he said that there was a shield for his lower body for protection. Then the x-ray generated around 200+ count pulse to the unit.

Edited by - EmfDev on 05/18/2018 08:48:13
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Reply #3

wergor

Austria
4 Posts

Posted - 05/22/2018 :  21:44:08  Show Profile  Reply with Quote
I did and asked for help on dose estimation a while back (https://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=4940 ) but did not yet have time to investigate it any further.
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Reply #4

EmfDev

106 Posts

Posted - 05/23/2018 :  09:53:41  Show Profile  Reply with Quote
It depends on what kind of x-ray, because the reading can be very different.
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Reply #5

n8xyn

USA
52 Posts

Posted - 05/23/2018 :  14:57:46  Show Profile  Reply with Quote
The tube took about 35,000 volts before arching (at which point the monitor went out and I back off). I don't intend to do this again as the voltage could prove fatal and the X-rays aren't safe, but I'm a curious little primate ;-)

Jim Whitaker
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Reply #6

ullix

Germany
213 Posts

Posted - 05/23/2018 :  23:02:15  Show Profile  Reply with Quote
Your 35000V could have produced 35keV X-rays, and the GMC-500 specs say it could detect x-rays from 30keV upwards, so, theoretically, you could have measured x-rays. However:

As shown in this pic (from http://folk.ntnu.no/floban/KJ%20%203055/X%20%20Ray/x-ray%20tube/x-ray%20tube.htm )

the vast majority of x-rays is below this max level, in the vicinity of 10keV. You would not get much of 30keV+ radiation, if anything at all.

Your 2740CPM at the counter would have been 18ÁSv/h (@0.0065 ÁSv/h/CPM). Based on US-FDA statements, US TV sets must have been limited to 5ÁSv/h worst-case (https://www.fda.gov/Radiation-EmittingProducts/ResourcesforYouRadiationEmittingProducts/ucm252764.htm ).

I just don't think that your device would have been so much more "efficient" in generating x-rays!

Rather, I believe this was more electrical noise that impacted the counter and other electronic. Next time some primate in your home tries to repeat the experiment, wrap the counter in aluminum foil and ground(!) the foil. I bet you'll get much lower "count".

If you do have an oscilloscope available, look here for how to measure noise or real signals at the counter:
http://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=4598

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