SiPM Cross-talk Amplification due to Scintillator Crystal: Effects on Timing Performance

The Dark Count Rate of the SiPM plays an important role in limiting the timing performance of the device when used for the readout of the light coming from a scintillator. We have already shown that it is possible to substantially reduce its effect on the Coincidence Resolving Time with a suitable noise compensation method. In this work we describe a different mechanism that limits the timing performance of the SiPM and it can be observed clearly when the contribution of the DCR is cancelled by the noise compensation. The mechanism worsens the CRT at higher over-voltages, actually limiting the maximum bias that can be applied to the device, and it seems to be related to the amplification of the optical cross-talk of the device due to the presence of the scintillator crystal. In this work we describe the experimental evidence of this phenomenon, its relation to the CRT performance of the devices as well as possible solutions.