Tests of irradiated Silicon Photomultipliers detectors for new high-energy space telescopes

Photon detection is a major issue in any high-energy astronomy instrumentation. One classical setup that has proven successful in many missions is the combination of photomultiplier tubes (PMTs) with scintillators, converting incoming high-energy photons into visible light, which in turn is converted in an electrical impulse. Although being extremely sensitive and rapid, PMTs have the drawback of being bulky, fragile, and requiring a high-voltage power supply of up to several thousand volts. The silicon photomultipliers (SiPM) appear to be a promising alternative to PMTs in essentially all their applications. We have started a R&D program to assess the possibility of using SiPMs for space-based applications in the domain of high-energy astronomy. We already presented first results of our characterization studies of SiPMs coming from three manufacturers. Each SiPM detector has been tested at low temperature and pressure to assess its performance in a representative space environment. For this purpose, we developed a dedicated vacuum chamber with a specific mechanical and thermal controlled system. After measuring dark current, dark count rate and PDE, we performed irradiation tests to understand the susceptibility of SiPM to radiation damage on two selected detectors. We report here on the results of these irradiation tests.