This is an optional step if you're using the carrier boards. If you're not and just soldering wires directly to the SiPM or doing it otherwise, skip this part.

All the SMD parts, the pin header and the SiPM itself. Orient yourself with the schematic and BOM. You can solder the pin header or, even better, use small wires instead.

Optionally, you can also skip this part and use the raw SiPM on its own and try to solder some small wires directly to it. That's not recommended though, as this whole process is quite delicate.

Center the SiPM on the scintillator crystal and put some silicon grease between the two parts to optimize the coupling (and minimize reflections)

Use black electrical insulation tape or similar non-transparent material to wrap the whole assemby, but watch out for the connector or cables, of course. This will reduce light passing to the SiPM to an absolute minimum, otherwise it won't work properly. You should use multiple layers of tape just to be sure.

Solder all the components of the detector board. Orient yourself with the schematic and BOM.

With a multimeter, adjust the SiPM voltage by turning the potentiometers. Each degree of rotation adds 30 mV to the output, so 10° are 300 mV and so on.

If you are using the recommended MicroFC-60035 SiPM, the best voltage is at about 29.6 V. This is at pretty much the middle position of the pot.

Depending on the scintillator size, desired energy range and resolution you need to change the gain. You can do so by turning the respective potentiometer on the board. If you increase the gain, this will also increase the average pulse duration of the gamma events and vice versa.

If you're just wanting to count pulses, just setting the pot to the middle position and leaving it there should be everything you need to do.

The ACTivity LED is there to help you with finding the perfect threshold and gain combination. Basically, if you can see the LED lighting up then the signal voltage is too high, so reduce the gain or increase the threshold until it's off again.

The last step for this to work is to set the peak discriminator to a useful level. This is done using the "threshold" potentiometer on the PCB. Turn it until you get to a certain point where the ACTivity LED goes from solid on to being "off" (actually it will blink extremely dimly and only in µs pulses).

This might change very slightly depending on your set SiPM voltage and preamp gain, you'll find the best value over time and experimenting.

That's it, welcome to the world of radiation detection and gamma spectroscopy! Happy tinkering!