Radiation damage effects of protons and X-rays on silicon photomultipliers

Silicon photomultipliers (SiPMs) are highly-sensitive photodetectors emerging as the technology of choice for many applications. In high-energy physics experiments and as the detectors for space instruments they are often exposed to a large amount of irradiation. In recent years, there has been an increasing interest in assessing the performance deterioration of such detectors after ionizing and non-ionizing radiation, such as protons, neutrons and X or gamma rays. It is interesting to compare the radiation damage effects on several types of SiPMs, to assess the main deterioration mechanisms on SiPM performances. In this work we report on the irradiation by protons and X-rays of several types of small-area (1 mm2) SiPMs, produced in FBK with different technologies. We show and compare the most interesting results of the online measurements, taken just after each irradiation step, for both irradiations. We performed and monitored the current variation during a room temperature annealing. Finally we characterized all the main functional performance of the irradiated SiPMs, highlighting the most interesting variations.