Operation of large-area APDs at cryogenic temperatures

We have investigated the possibility of using large-area APDs to readout inorganic scintillators operated at cryogenic temperatures. Such a detector was proposed by our group [1] as a way to built a polarized target to be used for neutrino physics, for the searches of axions, CP violation as suggested by some theoretical papers [2]. In particular we have showed in our previous work that a crystal of Gd 2 SiO 5 doped with Ce (GSO:Ce) can be polarized at temperatures close to LHe temperatures and magnetic fields of a few Tesla. In this work we have investigated in some details the performance of large-area APDs produced by Advanced Photonics Inc. down to LHe temperature, demonstrating that even in these extreme conditions the avalanche mechanism still provides gains in excess of a few thousand and the quantum efficiency does not drop below 5%, suggesting that these devices could still be used to readout low light pulses in a cryogenic environment.