SiPM timing at low light intensities

Silicon photomultiplier (SiPM) is becoming the photodetector of choice in many applications where good efficiency and precise timing are required. However, their timing performance at very low light intensities is still slightly limited, especially for SiPMs with at least moderately large active surface. Extracting the best timing information from single photon level pulses would be especially desired for the detection of Cherenkov photons in time-of-flight positron emission tomography (TOF PET). To improve the understanding of SiPM timing at low light intensities, we examined the performance of devices produced by four different manufacturers with a picosecond laser. The experiments were performed at a temperature of -25°C. We report on the timing performance of different SiPMs with special emphasis on the details of the double cell signals, where important effects that degrade the timing are most notable.