SrI2(Eu) detectors

[Rob Tayloe]

After I made a post under Detector Drivers about my initial use of a SrI2(Eu) detector with a Red Pitaya 125-14 and the PHA MCA program it was suggested that a topic be opened under Detectors.

I first heard of this detector from a blog on the Maximus Energy website. Dr. Max Fomitchev-Zamilov is an interesting fellow. He sells MCA devices and detectors and has free downloadable software that he created. His software and his MCA devices work with the PicoTech digital oscilloscopes.

Following is an image of one of his results with the strontium iodide detectors. I have not gotten such good results, but I am still learning and playing with this device. Also below are links to the vendor for strontium iodide detectors (CapeSym), PicoTech and Max's website and blog.

https://capesym.com
https://www.picotech.com
http://maximus.energy

Screenshot 2020-12-03 111228.jpg (96.34 KiB) Viewed 6827 times

SC-14x25-Cs-137-Spectrum.png (17.3 KiB) Viewed 6827 times

[GigaBecquerel]

What an impressive detector!
Thank you for all the links, the picoscope-mca is also very interesting, maybe it's possible to snatch those for cheap on ebay.

[Rob Tayloe]

The PulseCounter software from Maximus Energy can also work with a less expensive Pico Scope 2204A. At present Saelig in the US has this device for $115. Saelig also has some tutorial videos on YouTube. PicoTech has manuals and the SDK with some examples of how to use in one's own program. The PulseCounter software requires one to obtain the PicoScope SDK.

Links follow -
https://www.picotech.com/oscilloscope/2 ... ifications

PicoScope 2204A tutorial part 1
https://www.youtube.com/watch?v=-FZ5wrL1HMA

PicoScope 2204A Tutorial part 2
https://www.youtube.com/watch?v=ZLdF-hsQzKc

https://www.saelig.com/product/picoscope-2204a-d2.htm

[Rob Tayloe]

I spent a little time playing with the PicoScope2204A, the Strontium Iodide detector, and the PulseCounter software from Maximus Energy (link above). There are a lot of settings to tweak and clearly I have a ways to go. The set up is quite simple as shown in the photos below. These measurements were unshielded, i.e., in the open on my bench. I used a 47 ohm resistor with the strontium iodide detector. The SiPM was powered by three 9 volt batteries in series. The screen shots show a Cs-137 spectrum with the "presets" or settings selected. The other screen shot shows Co-60 and my fiddling with the calibration feature.

[GigaBecquerel]

But the $110 Picoscope is just 8 bit, gow does it get 2k channels from that?

[Rob Tayloe]

That the PicoScope 2204A has 8 bits of resolution is an interesting observation. This is because 2**8 is 256; to get even a thousand "channels" (or 1024) would require 10 bits. I also have a PicoScope 4262 with 16 bits of resolution that I will explore using. Alas, the higher resolution comes at a higher cost (around $1235 USD). So the image that I posted above is a curiosity. Did the PulseCounter software do some sort of interpolation to yield the spectrum image? Once I've gotten some data with the PicoScope 4262 I'll post those images.

[Rob Tayloe]

I was looking at some of the information on the PicoScope 2204A and the description found on the Saelig website states -

"Resolution enhancement adds up to four bits to the effective resolution of your oscilloscope, so a PicoScope 2200 can deliver up to 12 effective bits."

One wonders what magic is this "resolution enhancement"? Clearly the images that I obtained show greater than one would get from 8 bits of resolution. 12 bits of resolution is more believable. Further investigation is necessary.

http://www.saelig.com/product/picoscope-2204a-d2.htm

https://www.picotech.com/oscilloscope/2 ... ifications

[Rob Tayloe]

I found a bit more on the PicoTech website regarding the resolution enhancement for the 2000 series of oscilloscopes -

"Resolution enhancement
Resolution enhancement is a technique for increasing the effective vertical resolution of the scope at the expense of high-frequency detail. It is useful for resolving small signal details and for reducing unwanted noise. Unlike waveform averaging it can be used on single-shot signals."

PicoScope-3000D-Resolution-Enhancement.png (12.66 KiB) Viewed 6781 times

https://www.picotech.com/oscilloscope/2 ... 0-features

Thus, the effective resolution is able to support ~ 2000 channels.

[Rob Tayloe]

I obtained a more fresh set of sources from Spectrum Techniques and set about getting an energy calibration for some of my gamma spectrometer detectors and systems.

To better protect the SrI2(Eu) detector and SiPM I placed this in a small box as shown in the image below -

I decided to do the energy calibration for several detectors simultaneously. The detectors were surrounded by 2 inches of lead and are shown in the image below. The detectors are a Kromek RadAngel CZT, LaBr, NaI, and the Strontium Iodide. The small disc source is also shown -

I used a variety of MCA equipment and software. For the NaI detector I used the Spectrum Techniques UCS-30 and USX program. For the CZT RadAngel I used the Kromek KSpect software (no MCA is required, just a direct USB connection from detector to computer). For the LaBr I used a GS-USB-Pro with Theremino (I am not yet confident in my ability to accurately use PRA). For the SrI I used a PicoScope 4262 and the MaxEnergy PulseCounter software. The MCA equipment and computers are shown in the following images -

The energy calibration data obtained is shown below followed by a graph with polynomial fit -

Energ-cal-data.jpg (84.81 KiB) Viewed 6503 times

[Rob Tayloe]

I have been making measurements with the four detector configuration discussed above. I think that improvements can be made in the energy calibration. I am also monitoring drift in the energy calibration of the Strontium Iodide detector. While the SiPM has an integrated temperature sensor, I have not made use of this. I do monitor the ambient temperature of the room in which my equipment is set up. Most of the time the temperature is 74 degF (~23 degC) but can range from a low of 72 degF (~22 degC) to 76 degF (~24 degC). The detectors are surrounded by about 500 lbs (~227 kg) of lead which should help to keep the detector temperatures fairly constant. I am doing some longer series of measurements with various sources.

The plot below is from a bit over a week ago of a sample of monazite sand.