2"x2" CsI(Tl) detector

Scintillation crystals, PMTs, voltage dividers etc...
luuk
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2"x2" CsI(Tl) detector

Post by luuk » 15 Aug 2018, 03:50

I made a detector with a CsI(Tl) 2”x2” crystal.
The results are really good and it is very simple and easy to do.
If you interested please read the attachment.
Luuk
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30 minutes CsI(Tl) detector!.pdf
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iRad
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Re: 2"x2" CsI(Tl) detector

Post by iRad » 15 Aug 2018, 04:20

Very nice results Luuk! Do you remember the voltage you used on the R6231 PMT for your tests?

I already made a nice detector with the crystal you sent me, but I'm having some issue I think with the PMT I used. I get excellent resolution (about 6.5% for Cs137), but for some reason I'm not getting any signals below 100keV. I was away for a convention last week, so I'm trying to get caught up and will try another PMT with the crystal this week and report my findings when everything is working right (as it always does with your nice crystals). Thanks for sending mine rush, I appreciate that. Best, Tom
Cheers, Tom Hall / IRAD INC / Stuart, FL USA
Please check out my eBay Store: http://stores.ebay.com/The-Rad-Lab

luuk
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Re: 2"x2" CsI(Tl) detector

Post by luuk » 15 Aug 2018, 04:38

Hi Tom,




Thank for your comment.

To be honest it was really simple to make this detector, I did not found any problems,

the used hv is : Am-241=1100V, for Co-57=1000V for Cs137=890V and for C0-60=790V.

That is a litle higher than normal but that is due to the only 8 dynodes and the lower light output of the CsI(Tl).

I also used 3microsec shaping and a mainamp with 100x gain the gain is standard used for all our detectors in test.




Luuk

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iRad
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Re: 2"x2" CsI(Tl) detector

Post by iRad » 15 Aug 2018, 08:46

Luuk - Okay thanks, now I think I know exactly what the issue was. I also used a an R6231 8-stage PMT, which works excellent even at lower voltages with NaI(Tl), but now it makes sense that I was not using enough voltage to see the lower energies in the spectrum for this crystal where they should have fallen, since I was only using about 850 volts. Unfortunately I already pulled the probe apart in preparation for using another PMT, thinking that might have been my issue. As long as I have to put in another PMT, I think I will install a Hamamatsu R878 10-stage PMT. I have a few of them that I have been saving for special occasions.

Thanks again Luuk!
Cheers, Tom
Cheers, Tom Hall / IRAD INC / Stuart, FL USA
Please check out my eBay Store: http://stores.ebay.com/The-Rad-Lab

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Steven Sesselmann
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Re: 2"x2" CsI(Tl) detector

Post by Steven Sesselmann » 01 Sep 2018, 14:36

Hi All,

I got one of Luuk's beautifully prepared CsI(Tl) crystals, it arrived professionally packaged with test result sheet enclosed. (Thanks Luuk). The tests had been done with a Hamamatsu R6231, and I had seen Tom Hall (iRadinc) advertise some of these, and Tom was kind enough to send me one of those PMT's, it arrived yesterday. (thanks Tom).

In all the excitement I forgot to take photo's of the build, but the assembled crystal and PMT was quite a bit shorter than my regular 2" detectors with ADIT PMT's, so I cut down one of my housings by around 2", and fitted an SHV connector. I used SHV because we expect this PMT to run at higher voltage due to the lower light output of CsI crystals.

I ran a test it with the new GS-PRO-V1.6 Prototype, and it gave me a very nice spectrum with 6.8% resolution, despite a loose tolerance threshold of 10, and very basic shielding. The crystal tested at 6.5% on Luuk's high end equipment.

This is a very nice detector which I will keep for my own use.

Steven
IMG_2671.jpg
CsI(Tl) Detector
Luuk CsI.jpg
Cs-137 Gamma Spectrum with CsI(Tl)
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | beejewel.com.au |

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Steven Sesselmann
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Re: 2"x2" CsI(Tl) detector

Post by Steven Sesselmann » 01 Sep 2018, 16:21

With a little bit of tuning this fine detector is now giving me 6.3%, pretty happy with that.

Note how the Pb x-ray has been attenuated in this spectrum after I placed a 3" copper pipe over the detector.

Steven
6.3-percent.jpg
Cs-137 Spectrum 6.3%
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | beejewel.com.au |

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iRad
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Re: 2"x2" CsI(Tl) detector

Post by iRad » 01 Sep 2018, 21:58

Steven
Nice looking probe and excellent results. Certainly a keeper, especially since CsI(Tl) is excellent for field work. You now have a probe that is smaller than your standard 2" probe and with the high density of CsI(Tl) it's probably as versatile for a range of energies as a 3" NaI(Tl) probe would be. For field use, the CsI(Tl) crystal is nowhere near as fragile as NaI(Tl), and not as susceptible to thermal shock either. Cheers, Tom
Cheers, Tom Hall / IRAD INC / Stuart, FL USA
Please check out my eBay Store: http://stores.ebay.com/The-Rad-Lab

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pilgrim
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Re: 2"x2" CsI(Tl) detector

Post by pilgrim » 02 Sep 2018, 01:06

Very nice result Steven! Excellent work!
Daniel, Italy

luuk
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Re: 2"x2" CsI(Tl) detector

Post by luuk » 02 Sep 2018, 16:48

Hi Steven,

That is a great looking detector you build with it, and results are better as expected, just perfect!
I hope you can make good use of the detector like Tom said it is very good for field work.

Luuk

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Steven Sesselmann
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Re: 2"x2" CsI(Tl) detector

Post by Steven Sesselmann » 02 Sep 2018, 17:32

Yes, now I just have to build myself a very low background shield like Luuk, so I can get a flat Compton plateau like the test sheet.

Steven
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | beejewel.com.au |

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