Proton Irradiation and Thermal Recovery of SiPMs for LEO Missions

Silicon Photomultipliers (SiPMs) are optical sensors widely used in space applications due to their high photon detection efficiency, low power consumption, and robustness. However, in Low Earth Orbit (LEO), their performance degrades over time due to prolonged exposure to ionizing radiation, primarily from trapped protons and electrons. The dominant radiation-induced effect in SiPMs is an increase in dark current and dark count rate, which can compromise detector sensitivity. This study investigates the potential of thermal annealing as a mitigation strategy for radiation damage in SiPMs. We designed and tested PCB-integrated heaters to selectively heat irradiated SiPMs and induce recovery processes. A PID-controlled system was developed to stabilize the temperature at 100 °C, and a remote-controlled experimental setup was implemented to operate under irradiation conditions. Two SiPMs were simultaneously irradiated with protons at the EDRA facility, with one undergoing thermal annealing between irradiation cycles and the other serving as a control. Throughout the experiment, dark current was continuously monitored using a source measure unit, and I–V curves were recorded before and after irradiation. The results show that thermal annealing effectively reduces dark current, supporting its feasibility as a low-complexity strategy to mitigate radiation damage in space-based SiPM applications.