Hi there! I have been doing some electronics and here is my thoughts about how to connect things. Any help will be very welcomed. My idea is to create a PCB after testing everything on a breadboard. !

Hmmm. Looking up scintillometers, I see they are advertised as "large aperture", so you may need an array of photo[diodes,cells], which adds a lot of complexity, matching, summing etc,but maybe you could get away with a condenser lens.