I have been trying validation process. Of NaITl 1" crystal and one 6x6 SiPM. However, I keep having “destorted” data at SiPM readout. I am tracking optical phontons from scintillation process and record all photons which can get via glass from scintillator to the SiPM and then kill them (so any king of backscattering is ruled out). Counting is ended at the end of event, and event consists of one decay of Cs-137. And I am getting somtehing like this: Photopeak is clearly visible, but, where compton edge is, something weird arises. I have been triing to simulate crystal behaviour withou SiPM and recorder all absorbed photon and nothing like this was visible.
Thank you for your opinion on this.