Measurement of the response of Silicon Photomultipliers from single photon detection to saturation

The development of Silicon Photomultipliers (SiPM) is very dynamic and a large variety of types exists. Important SiPM characteristics include the size and number of pixels, the gain, the photon detection efficiency (PDE), the recovery time, and correlated noise. SiPMs are particularly suitable for single-photon detection and low-intensity exposures. For photon numbers (PDE corrected) reaching the number of pixels, however, the sensors saturate. In this work, we present comprehensive response measurements for state-of-the-art SiPMs using an experimental setup based on a tunable picosecond laser. Several models are applied to the measured response curves, taking particularly correlated noise and saturation effects into account. Sensors with different numbers of pixels and different design are compared, some of which exhibit an over-saturation behavior. The results are discussed in the context of high-granularity calorimeters developed for future particle physics experiments employing millions of SiPMs. For these projects the full dynamic range of the sensors has to be exploited, thus an understanding and calibration of the saturation behavior is crucial.