Characterization of Radiation Damage Effects of Protons and X-rays in FBK Silicon Photomultipliers

SiPMs have been employed in a growing number of applications, like medical imaging, LiDAR, etc. They are quickly replacing photomultiplier tubes and other detector technologies in high-energy physics (HEP) experiments, and for the readout of scintillators in gamma-ray detectors for space experiments. In such applications the SiPMs receive a significant dose of particles (such as protons and neutrons) as well as X and gamma rays. While the effect of radiation in silicon detectors biased below the voltage where avalanche multiplication becomes significant is well studied, the literature is not as much concerning Geiger-mode silicon-detector. In this work we studied in detail and with a systematic comparison, the effect of radiation on the performance of several SiPM technologies, produced by FBK. In particular we irradiated several chips with 74 MeV protons and with 40 keV X-rays, in two separate experiments. Each time we monitored their dark and light current-voltage curves after every irradiation step. We also studied the annealing after irradiations for few days at room temperature. Finally we characterized functionally the performance of irradiated device after irradiation and annealing, highlighting the differences between p-type silicon devices, n-type ones, and based on layout of the microcells.