Scintillation Crystal conversion

Scintillation crystals, PMTs, voltage dividers etc...
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sgt_bear
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Scintillation Crystal conversion

Post by sgt_bear » 07 Dec 2019, 23:10

After looking for the perfectradiation detector, i've come to an end and accepted that there is no ultimate device for the hobbyist.
I'm looking for a high-tech device (logging, gps, external detector capability etc) but there are only a few, and these are priced for professionals, which means above 1500$
Since i'm interested in electronics, i would like to build my own.

The detector of choice would be a scintillation crystal connected to a sipm. This would save space, have a higher resolution than a geieger tube, and does not need high voltage.
I start looking for either bgo or csl crystal on the market

My current problem is, that i have no idea how it would be reasonable accurate to translate cps to uS/vh in terms of scintillation.

Geiger tubes are easy, the have a fixed conversion factor (eg. 108 for the LND-712) so the counts in cpm can be converted to uSV/h really easy. In terms of scintillatione, a huge number of factors are possible like

- Crystal Material
- Crystal Geometry (Size, shape etc)
- Sipm type and connection

Can anyone provide information how these conversions work? I assume they have to be possible, since new personal radiation detectors usually use scintillation detectors (like poilmaster etc).
Any help appreciated.
- Jonathan from Switzerland

James Luck
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Re: Scintillation Crystal conversion

Post by James Luck » 12 Feb 2020, 06:26

On the subject of counts to Sieverts, it would be best suited to maybe go from Counts/Sec to Rem/ min, or hour. As counts can rough estimate to R and R can be translated to Sieverts. yet couldn't you put into software the necessary script to equate counts from detector to Sieverts? such as using a raspberry pie or ardiuno running script. this may take some effort on experimenting with crystals and counting circuits, i could have sworn i've seen a hackaday on someones project on making a scintillation detector around a raspberry pie. If my memory tells me right he went from Counts to Sieverts.

One thing to keep in mind is crystal size, such as GM detector size. the larger the more sensitive, but may over calculate the actual measurement. Yet a small detector may under calculate the actual radiation level.

Heres some links to look at:

http://www.blackcatsystems.com/GM/conve ... _mRhr.html

https://www.remm.nlm.gov/radmeasurement.htm

This ones probably more than needed but a cool video.
https://hackaday.com/2019/08/19/diy-gei ... te-clicks/

Just somethings to look into, james.
James luck
Chicago Ill, USA.
Hobbyist, primary meter: refurbished Eberline Esp-1.
Probe: 3 inch plastic scintillator kit from iradinc.

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Steven Sesselmann
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Re: Scintillation Crystal conversion

Post by Steven Sesselmann » 12 Feb 2020, 09:24

Jonathan,

I think the only sensible way is to build it and then calibrate it to a known source. There are too many variables to try and calculate it.

Steven

James Luck
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Re: Scintillation Crystal conversion

Post by James Luck » 12 Feb 2020, 14:32

Steven Sesselmann wrote:
12 Feb 2020, 09:24
Jonathan,

I think the only sensible way is to build it and then calibrate it to a known source. There are too many variables to try and calculate it.

Steven
I'm with Steve on this one, I'd just stick to a known source such as a 1uCi Cs-137 source. figure its count rate and then equate to dose.
James luck
Chicago Ill, USA.
Hobbyist, primary meter: refurbished Eberline Esp-1.
Probe: 3 inch plastic scintillator kit from iradinc.

James Luck
Posts: 10
Joined: 10 Oct 2019, 04:16
Contact:

Re: Scintillation Crystal conversion

Post by James Luck » 23 Feb 2020, 09:56

On thought about this you could either go for a 1uCi Cs-137 source which is preferred by many, or if unable to pick one up, there are places that will rent lab sources.
If size of sample you can use say a .25uCi source and do the conversion of strength to retrospective dose. if this is the path your interested, ill have to do some looking again, there are a few guys on youtube who explain how to calibrate to a smaller than 1uCi source of Cs-137.

another source that is often used because of its known decay and activity, along with its civilian industrial / medical use is Co-60, it'll be hard to find the conversion of energy to dose for less than 1uCi though. also i dont know the cost comparison between purchasing Cs-137 and Co-60.
James luck
Chicago Ill, USA.
Hobbyist, primary meter: refurbished Eberline Esp-1.
Probe: 3 inch plastic scintillator kit from iradinc.

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