Radiation damage on SiPMs for space applications

Silicon Photomultipliers (SiPMs) are very sensitive photo-detectors that experienced a big development in the last years in several applications, like LIDAR, astrophysics, medical imaging and high energy physics (HEP) experiments. In HEP experiments, in particular, they are often exposed to significant radiation doses. The main purpose of this manuscript is the characterization of several FBK SiPM technologies when exposed to 74 MeV protons with a total fluence comparable to the one that they would experience in space along circular Polar, Low Earth Orbits (LEO) during a five years mission. In this work, we estimated the expected proton fluences along the selected orbit, by means of the SPENVIS software. Several fluence steps were chosen to consider dense fluence intervals and have a more accurate sight on the whole damage process. We estimated a maximum fluence achieved during the tests of 6.4×1011 neq/cm2. Based on such simulations, we irradiated several SiPM technologies. We developed a custom experimental setup, which was used to perform online reverse voltage–current, right after each irradiation step, to minimize the effect of the annealing on the measurement. The results are then displayed, in particular the currents, the noise and the Photon Detection Efficiency. Also a 30-days study on the annealing of the devices was performed. Lastly, the conclusions are drawn on the basis of the Signal-to-Noise Ratio (SNR), taking into account the standard parameters of famous satellites using similar orbits as the ones considered into this work.