Influence of the active area size and read-out method on the timing performance of SiPMs coupled to LYSO scintillators

In this work we report on the coincidence resolving time performance of SiPMs with different sizes, produced at FBK, coupled to the same LYSO scintillators. The measurements are performed both with and without the differential leading edge discriminator at three different temperatures, 20 °C, 0 °C and −20 °C. The photo-detectors feature an active area of 2×2 mm2 and 4×4 mm2. The scintillators have a cross-section of 1.8×1.8 mm2 and height of 10 mm. The measurements show that, once we eliminate the effect of noise on the timing measurements, we obtain similar coincidence resolving times for the two SiPM sizes considered. This means that the SiPM capacitance, at least up to 4×4 mm2, is not a limiting factor.