Radiation damage on Silicon Photomultipliers from ionizing and non-ionizing radiation of low-earth orbit operations

Silicon Photomultipliers (SiPMs) are single photon detectors that gained increasing interest in many applications as an alternative to photomultiplier tubes. In particular in the field of space experiments, where volume, weight and power consumption are a major constraint, their advantages like compactness, ruggedness, and their potential to achieve high quantum efficiency from UV to NIR, makes them ideal candidates for spaceborne, low photon flux detectors. During space missions however, SiPMs are usually exposed to high levels of radiation, both ionizing and non-ionizing, which can deteriorate the performance of these detectors over time. The goal of this work is to compare process and layout variation of SiPMs in terms of their radiation damage effects to identify the features that helps reducing the deterioration of the performance and develop the next generation of more radiation tolerant detectors. To do this we irradiated with protons and X-rays several NUV-HD SiPMs with small area (single microcell, 0.2x0.2 mm2 and 1x1 mm2) produced in FBK. We performed online current-voltage measurements right after each irradiation step and a complete functional characterization before and after irradiation. We compare the results and show the most promising variations for future production of SiPMs for space applications.