SrI2(Eu) detectors

[Rob Tayloe]

The Red Pitaya 125-14 starter kit can be purchased from the European-based Red Pitaya website -

[broken link removed - Steven]

Or from Digi-Key in the US -

https://www.digikey.com/en/products/det ... 07/6579245

[Rob Tayloe]

Although it is a little bit of "apples to oranges" comparison, I will never-the-less show some more results using four different CapeScint MacroPixel scintillation detectors equipped with SiPM. The detectors are all 14x14x25 mm and are NaI, CsI, nEL, and SrI(Eu). The datasheets for these devices are given in an earlier post. Power is by three 9 volt batteries (~ 27 volts) using a 50 ohm termination resistor. Above I showed results with the Red Pitaya 125-14 using the MCA-PHA software and a spreadsheet. Below are the same detectors with a PicoScope 4224 and 4262 oscilloscopes using the Max Energy (previously free) Pulse Counter software. The x-axis is not energy, rather it is "bins". Other than noted, the figures were generated by data imported into a spreadsheet. A small thorite rock was the radioactive source. The PicoScope 4224 seems to have been discontinued (perhaps that is why is was heavily discounted when purchased).

Links to PicoTech and vendor websites are given -

https://www.picotech.com/oscilloscope/4 ... 2-overview

https://www.saelig.com/picoscope-4000/PSPC10BIT009.htm

https://www.saelig.com/product/pq288.htm

https://www.farnell.com/datasheets/3178697.pdf

Following is a screen capture of the Max Energy Pulse Counter software (previous version) being used with the SrI(Eu) detector and PicoScope 4262. For each detector it is necessary to tweak some of the settings.

Next are spreadsheet generated images (both linear and Y-log axis) images are shown -

sri-th-4262.jpg (94.38 KiB) Viewed 1289 times

sri-th-4262-ylog.jpg (95.17 KiB) Viewed 1289 times

sri-th-4224.jpg (88.99 KiB) Viewed 1289 times

sri-th-4224-ylog.jpg (91.43 KiB) Viewed 1289 times

csi-th-4224.jpg (90.13 KiB) Viewed 1289 times

csi-th-4224-ylog.jpg (83.69 KiB) Viewed 1289 times

nai-th-4224.jpg (85.49 KiB) Viewed 1289 times

nai-th-4224-ylog.jpg (84.83 KiB) Viewed 1289 times

[RobertD]

Very interesting comparisons, Rob. Did you use the same settings in the MCA-PHA software for all four detectors?
I'm using the RedPitaya 125-14 for gamma spectrometry with this app: https://github.com/pavel-demin/redpitay ... elanalyser
It has to be added manually via terminal to the ecosystem, runs directly on the RedPitaya and is accessible via browser. Collected spectra can be exported as csv for further processing.

[Rob Tayloe]

Here are three screen grabs for the SrI2(Eu), CsI, and NaI detectors with SiPM from CapeScint using the MCA-PHA program with the Red Pitaya 125-14. I did not do much (if any fooling with the settings). There definitely appears to be room for improvement with my data collection. Mostly I was just trying to see if the detectors would yield a reasonable spectrum from various sources..

SrI2(Eu) with thorite

CsI with thorite

NaI with thorite

[Rob Tayloe]

I am using a Windows 10 or 11 laptop with the Red Pitaya. I open the Chrome browser and enter the local IP address assigned by my router. A Red Pitaya screen is displayed with an icon for MCAPHA. On opening that icon instructions are given for downloading a zip file. Once downloaded, the zip file is uncompressed. Within a folder is the mcapha.exe program. On executing that program (whilst leaving the Red Pitaya MCAPHA icon "open") I get the screen view as shown above. Once I enter the local IP address in the top left corner and hit "connect" I am ready to begin collecting data.

The only changes that I've found to make any difference is with the lower threshold (usually I pick 0 or another small number; the default is 300). Changing the upper threshold appears to have no effect; the default is something a bit north of 16 kbins. I don't see a "gain" adjustment; I suppose that one could install some instrument op amp between the detector and Red Pitaya to make more use of the available bin space. Usually 2k bins is adequate for these detectors.

The default data collection time is 1 min. I usually count for a longer time. Then the data is saved using the "register" button. That data is imported into a spreadsheet.

The newer version of MCAPHA looks interesting, but I have no idea how to make this work under Windows. It appears that Linux-type of commands area used. I welcome anyone's instructions for getting an updated MCAPHA program operating under Windows for the Red Pitaya 125-14.

[RobertD]

Rob,
The MCA program I was referring to is not running on the Windows machine, but on the RedPitaya itself. It can be executed and controlled by any browser on any device in your local network.
I'll write some instruction for you later.

[RobertD]

BTW, looking at your spectra, I was surprised about the big difference between CsI and NaI detectors, considering the fact that they are in a similar price range.
Also, spectra taken with the Capescint MCA seem to be a lot cleaner than the spectra recorded with the RedPitaya with the same crystal. I assume this is due to the temperature compensation built into the Capescint MCA.

[NuclearPhoenix]

BTW, looking at your spectra, I was surprised about the big difference between CsI and NaI detectors, considering the fact that they are in a similar price range.

I assume this is due to the slightly higher density and light yield of CsI compared to NaI, which would explain the higher efficiency at higher energies. Provided that the crystals are the same size of course...
But there are probably a lot more people on here who understand this better than me! :)

[Rob Tayloe]

Also, spectra taken with the Capescint MCA seem to be a lot cleaner than the spectra recorded with the RedPitaya with the same crystal. I assume this is due to the temperature compensation built into the Capescint MCA.

The CapScint MCA coupled to the SrI2(Eu) detector and SiPM is optimized for that system and has temperature stabilization. The software used to drive this small MCA system is downloadable from the CapeScint website for each detector. Of course, the software only works with the CapeScint MCA system.

Similarly good results with the SrI2(Eu) detector, but not temperature stabilized, can be obtained using the PicoScope 4262 Oscilloscope with the Maximus Energy Pulse Counter software. The Pulse Counter software now sells for $100 and has many user controlled settings (meaning that one must "fiddle about" with the software a bit to obtain optimal results). The cost for the SrI2(Eu) detector with SiPM (but no MCA) with a PicoScope 4242 and Pulse Counter software is about the same as the CapeScint MCA system with the 14x14x25 mm SrI2(Eu) system.

With the Red Pitaya with the Windows downloadable MCA-PHA software the spectra obtained may be less than optimal due to the incomplete collection of the pulse from the SrI2(Eu) with SiPM. A while back, when I first obtained the Red Pitaya 125-14 unit I asked the CapeScint folks about this issue. More discussion is found within the thread linked below -

viewtopic.php?f=15&t=851&start=20

I would very much appreciate having some instructions about installing the new version of MCA-PHA on the Red Pitaya.

[Rob Tayloe]

BTW, looking at your spectra, I was surprised about the big difference between CsI and NaI detectors, considering the fact that they are in a similar price range.

I assume this is due to the slightly higher density and light yield of CsI compared to NaI, which would explain the higher efficiency at higher energies. Provided that the crystals are the same size of course...
But there are probably a lot more people on here who understand this better than me! :)

All of the scintillation detectors that I have from CapeScint are of the same small size. The detectors are 14x14x25 mm. I found that this size was very much less expensive than the larger detectors and was adequate for my "hobby" purposes.