Evolution of MPPC properties as a function of neutron fluence

Evolution of spectroscopic properties of two types of Multi-Pixel Photon Counters (MPPC) during neutron irradiation is reported. In such experiments the change of MPPCs characteristics is a serious issue. A series of neutron irradiation tests were performed at the National Centre for Nuclear Research (NCBJ, Poland) and Joined Institute for Nuclear Research (JINR, Russia). Two types of neutron sources were used: PuBe with continous energy spectrum up to 11 MeV and mono-energetic 4.8 MeV neutrons produced in (d,d) reaction. For both cases the fluence in the range of 10
¹⁰
n/cm
²
was achived.