  Radiation damage of J-series silicon photomultipliers (SiPMs) has been
studied in the context of using these photodetectors in future space-borne
scintillation detectors. Several SiPM samples were exposed to 101.4 MeV
protons, with 1 MeV neutron equivalent fluence ranging from 1.27*10^8 n/cm^2 to
1.23*10^10 n/cm^2 . After the irradiation, the SiPMs experienced a large
increase in the dark current and noise, which may pose problems for
long-running space missions in terms of power consumption, thermal control and
detection of low-energy events. Measurements performed with a CeBr3
scintillator crystal showed that after exposure to 1.23*10^10 n/cm^2 and
following room-temperature annealing, the dark noise of a single 6 mm square
SiPM at room temperature increased from 0.1 keV to 2 keV. Because of the large
SiPM noise, the gamma-ray detection threshold increased to approximately 20 keV
for a CeBr3 detector using a 4-SiPM array and 40 keV for a detector using a
16-SiPM array. Only a small effect of the proton irradiation on the average
detector signal was observed, suggesting no or little change to the SiPM gain
and photon detection efficiency.
