Silicon Photomultipliers (SiPMs) are a novel generation of photon detectors designed as an array of independently operated Geiger-mode APDs (pixels) with common output. SiPM provides proportional detection of low-level light pulses starting from single photons with remarkable photon number and time resolution at room temperature. Now they are worldwide recognized to be competitive with vacuum photomultiplier tubes (PMTs) and avalanche photodiodes (APDs) for scintillation and Cherenkov light detections in such areas as particle physics and nuclear medicine. Well-known specific drawbacks of SiPMs are excess noises caused by stochastic processes of crosstalk and afterpulsing as well as non-linearity and saturation of SiPM response to intense light pulses due to limited number of pixels and non-instant pixel recovery. This study presents an analysis of SiPM performance based on probability distributions of the key stochastic processes affecting SiPM response: photo-conversion, dark generation, avalanche multiplication, crosstalk and afterpulsing, non-linearity and saturation losses. SiPM performance in photon number resolution (energy) is represented in terms of specific excess noise factors of these processes identified as comparable metrics of their contributions. SiPM time resolution is shown to be defined by photon number resolution and by temporal profiles of photon arrival and photon detection time distributions, and a single electron response. Analytical results of this approach are applied to compare a performance of the modern SiPMs with each other and with conventional PMTs and APDs in typical scintillation and Cherenkov detection applications. The results also seem to be useful for SiPM characterization, selection, and application-specific optimization as well as for SiPM design improvements.

Cockcroft Institute / University of Liverpool / Lebedev Physical Institute RAS