Gamma Spectrometry Forum

Hello, I'm Addison
I'm a college student studying chemistry and have been interested in radiation and nuclear science about as long as I can remember. During the school year I work at the nuclear research reactor at my school which has allowed me to do some very interesting projects, including one on trace elements in trinitite and partially re-calculating the trinity device yield from it.
It's also given me a fair bit of experience with gamma spectroscopy, and I've been wanting to build my own system for personal, portable, and summer use. Currently I have an old Johnson GSM-10 count rate meter and I'm planning on tapping the pre-amp. I still need to find a suitable detector though, I've been looking at a

[broken link removed - Steven]

scintillator. I'm not certain whether that would be too likely to work or have particularly good resolution though so I may go the route of building my own detector instead. It has been very cool to find this and all of the resources here.

Welcome Addison!
If your experience is like mine you'll find a helpful and knowledgeable online community here. Though I'm not the most expert at gamma spectroscopy (yet) I would suggest that you look at amazon.com for the detector you linked to in your post. (It is available for less money and for lower shipping costs there.) Saint-Gobain makes a variety of really nice detectors but I'm unfamiliar with the one you selected. However, the following may be useful as you seek to construct your own system:
(1) The bigger the scintillating crystal the more gamma rays get converted into readable signal. Small crystals result in smaller signals per unit time.
(2) The material you use in the scintillating crystal makes a difference in how many gamma rays get converted into readable signal.
(3) How the spectra look (i.e., spectral quality) depends quite a bit on how the system is configured, the noise in the amplification system, how the system is calibrated, etc. etc. etc. (I wished I had understood the intricacies of this more before I started.)
Overall, the small Saint-Gobain scintillator may work just fine but the number of samples it will perform well for might be limited.

Might I suggest you look at iRad's eBay store if you're inclined to build your own gamma spectroscopy system and components? (There are several users on this forum that have online stores from which you can purchase useful and fun materials, detectors, systems, etc.; I've personally purchased several items from iRad [broken link removed - Steven]and have had excellent experience with the items therefrom.) iRad has detector kits that can be purchased for more than the crystal you identified but should result in the size and quality that will generally provide great spectra. (I've been watching the [broken link removed - Steven] kit as a lower cost option to trying a plastic scintillating detector.)

Good luck!

Hi Addison,

Welcome to the forum..

I would give the square detector a miss and look for a NaI(Tl) detector from a seller who is prepared to show you a spectrum taken with the detector. the seller would normally provide a spectrum of Cs137 showing a resolution of 8% or better.

I have a whole box full of those square detectors and most of them have a resolution around 15%, I intend cutting them open to rescue the small 1" PMT's which in most cases are still good.

Steven

Thank you both for the advice, looks like I'll most likely be building one then. For portability and budget I'll probably get a new 1" crystal and look at some of those PMT kits. I'm pretty lucky that if I ever do find myself needing really high sensitivity and resolution I have access to the HPGE detectors at my college.

Speaking of which, I have a few sets of spectra from projects I've done in the past that I'd be happy to share here. There are a few long trinitite counts and then a couple different things from after neutron bombardment.

Addison

Hey Addison,

Best of luck with your build! Please post details of your efforts on the forum as it's the kind of stuff that we love to see!

I posted previously, " (I've been watching the [broken link removed - Steven] kit as a lower cost option to trying a plastic scintillating detector.)" Recent correspondence with iRad indicated that this would be an INAPPROPRIATE detector material for gamma spectroscopy (but not bad for detection) and I wanted to pass that on to make sure you were getting the best advice possible.