SrI2(Eu) detectors

[MartinM]

Sorry, I don't have any X-Ray technology.
Just finished the energy correction/calibration. Was struggling with that as it didn't work until I figured out that the channel/energy entries in the table need to be in ascending order.

Lu176

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Aged Am241 with small Np237 buildup

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[MartinM]

Co60, very nice resolution:

[MartinM]

Thorium metal:

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[Mike S]

I know this thread has been quiet for almost two years, but I didn't think my questions were worth starting a new thread.

Those of you using the CapeScint USB MCA, are you still happy with the software and support?

I have a CapeScint SC-14x25c-SiPM-T SrI2(Eu) detector I bought in 2022 and I'm considering buying their MCA (largely for temperature compensation). I see that Digi-Key sells some of their products now, but otherwise there's not a lot of news coming out of CapeScint these days. I have been hesitant to lock into their proprietary software, so I just wanted to check that folks are still happy before make the purchase. (Note: I am aware they sell an older version of the MCA on eBay, but it is not compatible with the latest software and lacks some features.)

Also, has anyone seen any comparisons with the larger SrI2(Eu) detector, SC-28x51c-SiPM-T?

Since CapeScint doesn't publish much in the way of performance data, I'm wondering how much difference the larger crystal makes.

[Rob Tayloe]

I have both the CapeScint USB MCA SrI2(Eu) detector and the stand-alone SrI2(Eu) detector with SiPM. Both detectors are 14x14x25 mm. With the stand-alone detector I use the PicoTech 4262 oscilloscope with Windows PC software from Maximus Energy; the software is no longer free. The current price (as of 1 March 2025) for the Pulse Counter Pro software is $995 USD; the Pulse Counter Lite version of the software is $195 USD. The software that I am using is very similar to the Lite Version. The PicoTech 4262 is around $1500 USD. The Pulse Counter software is a bit "fiddley". There are very many settings that one can adjust which affect the results.

CapeScint has made a number of improvements to the software used with the USB MCA scintillation detectors; this software can be freely downloaded from the CapeScint website. It is very easy to plug the USB cable into the detector, run the software, and begin acquiring spectra.

If there are no significant temperature changes during a measurement the results are quite similar for both set-ups. Comparison results are shown in earlier posts in this thread. A larger detector will have a higher efficiency, particularly for more energetic photons; the larger detector will be more expensive.

Following are relevant links -
https://capescint.com/products/
https://capescint.com/product-category/ ... ssemblies/
https://capescint.com/product-category/ ... on-probes/
https://www.picotech.com/oscilloscope/4 ... 2-overview
https://www.saelig.com/product/PSPC10BIT009.htm
https://www.amazon.com/Pico-PicoScope-1 ... B0153KEQEW
https://maximus.energy/index.php/produc ... unter-pro/
https://maximus.energy/index.php/product/pulsecounter/

[Mike S]

Thanks Rob!

I have been following this thread for a while and read through it again today; you've posted an amazing amount of information. I haven't had much time to focus on gamma spectroscopy recently and I just wanted to make sure nothing had changed for the worse with CapeScint before I spent more money on their products.

I often do multi-day measurements of weak sources and because my work area is not tightly temperature controlled, I've found the temperature swings are limiting my resolution. I've considered adding temperature control to the detector or the whole shield, or even rolling my own temperature compensation. At this point I like the idea of having the temperature compensation and other features of the USB MCA in a portable package that I don't have to build from scratch. Of course the tradeoff is cost, but on that I've reached acceptance. I plan to buy a non-integrated MCA so I can use it with the detector I already have; it's not listed on their website anymore, but I assume they will still sell me one. I'll contact them in the next few days.

[Rob Tayloe]

I do not think that the CapeScint USB MCA is a simple plug and go (into a detector) type device. It may well be necessary for you to send your detector back to them in order to correctly mate the MCA to the detector; i.e., I think that there are internal settings that must be made to the MCA for each detector. I would suggest that you contact CapeScint and discuss your needs. Several years ago I made similar inquiries and learned of the need to specifically mate the USB MCA to the detector, perhaps things have changed.

If you are familiar with programming microcontrollers (e.g., Arduino) or single board computers (e.g., raspberry pi) then you might be able to have a more stable temperature environment with a heater / cooling set-up. This is also an interesting way in which to learn about system feedback. I am fortunate in that my basement set-up generally stays within 22 +/- 2 degC year round.

[Mike S]

Update: CapeScint does sell the separate USB MCA and they even have them in stock. I'm not sure why, but after our initial conversation there was a multi-week delay getting some questions answered and getting it on order (I'm guessing they only have once person who handles sales). Once they got back to me they shipped it the same day (it should be here later this week). During the initial conversation I asked if they were going to switch to a USB C connector and was told that they are currently focused on industrial products and don't have any hardware updates currently planned for the MCA. They have a few slightly different hardware versions and I chose the one that is optimized for my detector.

Reading through the manual, it will take some time and effort to collect data and setup the temperature compensation and a few other calibration actions, but it is designed to work with a broad range of their SiPM detectors.

[Rob Tayloe]

How much was the separate USB MCA? I was under the impression that there were some internal settings in the USB MCA that CapeScint needed to make. I guess that one can purchase the USB MCA and attach it to the detector one's self. Was there any guidance about securing the USB MCA to the detector (e.g., use a strong tape [gorilla or duct])? Did you get any different or special software to upgrade the MCA firmware or to store temperature correction data?

[Mike S]

The cost was $1540 (USD) plus tax and shipping, so there certainly are other cost-competitive options. I finally decided I wasn't going to get around to putting together a different solution and I liked the small size and physical simplicity. They do have an older version for sale on eBay (last I looked) that is half the cost but it doesn't have a housing, has to use an older version of their software, and it has (from my perspective) a less desirable temperature compensation methodology. From what I remember, the old one used software-only temperature compensation where the newer MCAs actually adjust the bias voltage. There were four different hardware versions available and I bought hardware version v1.0.62 since that is what (I'm told) works best with my little SiPM SrI(Eu) detector. There is no indication on their website that they even offer a separate MCA, but I think they used to have them listed back when I bought my detector.

The MCA just plugs into the back of the detector using the existing pins (the MCA has a matching socket). I suppose I could make a sleeve to give the connection more mechanical strength if I think that's needed.

The software is the same as the integrated MCAs. The temperature compensation will need to be calibrated with my detector, but the software manual implies that even the integrated detectors need to be calibrated by the end user. Calibrating the temperature compensation looks like a bit of work, but it is definitely designed and documented to be performed by the end user.

I liked the idea of a separate MCA so I could potentially buy other CapeScint detectors and use the same MCA (of course I'd have to calibrate the MCA for any new detectors). Also, there's some cost recovery if one or the other fails. The real thing that bought me to this point was at the time I bought the detector I didn't feel comfortable spending the additional amount for the integrated MCA. Oddly, at lest on DigiKey, the integrated detector costs a little more than buying them separately.

Integrated detector and MCA: SC-MP-MCA $3245

Detector only: SC-14X25C-SIPM-T $1,655
MCA Only (what I paid direct, NOT available on DigiKey): $1540
Total: $3,195

Rob, thanks again for sharing your experience with CapeScint equipment, it definitely helped me make some expensive decisions.