Some new tests are out with the latest MicroFC SiPM Array Board. It features a 2x2 grid of the standard MicroFC 6mm SiPMs resulting in a much larger active area compared to the single MicroFC carrier board. It's not much bigger in size too, so the ratio of active/total area has improved a lot!

You can get an output of each individual SiPM or just connect all of them in parallel via a jumper on the PCB. If you do that, you can use the board just like a single SiPM -- your detector won't know the difference. Using this "parallel mode" you can use the board with the Open Gamma Detector without any modifications.

All the hardware is fully open-source of course, head over to the GitHub repo for some more info: https://github.com/OpenGammaProject/MicroFC-SiPM-Array-Board

Here you can see the test results using a 6.6% NaI scintillator and a Cs-137 source:

As you can see, we got to <8% energy resolution @ 662 keV, which is already pretty close to the specified resolution of the manufacturer. Needless to say, I'm quite happy with the results ;)

Maybe it would be possible to get every so slightly better (0.x%) with some additional EMI shielding and software tweaking.