Characterization of silicon photomultipliers for new high-energy space telescopes

Photon detection is a major issue of high-energy astronomy instrumentation. One classical setup that has proven successful in space missions is the combination of photomultiplier tubes (PMTs) with scintillators, converting incoming high-energy photons into visible light, which 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 thousands volts. The silicon photomultipliers (SiPM) appear to be a promising alternative to PMTs in many applications such as small satellites. We have started a R&D program to assess the possibility of using SiPMs for space-based applications in the high-energy astronomy domain. We present here the results of our characterization of SiPMs coming from several manufacturers. Each detector has been tested at low temperature and pressure to study its performance in a representative space environment. For this, we developed a dedicated vacuum chamber with a specific mechanical and thermal controlled system. Once dark current, dark count rate and PDE were measured, we made irradiation tests on two selected detectors to understand the susceptibility of SiPM to radiation damage. Finally, we aim to perform thermal cycling and mechanical tests on detectors and study their coupling to scintillators, in parallel with their space qualification.