  Silicon Photomultipliers (SiPMs) are quickly replacing traditional
photomultiplier tubes (PMTs) as the readout of choice for gamma-ray
scintillation detectors in space. While they offer substantial size, weight and
power saving, they have shown to be susceptible to radiation damage. SensL
SiPMs with different cell sizes were irradiated with 64 MeV protons and 8 MeV
electrons. In general, results show larger cell sizes are more susceptible to
radiation damage with the largest 50 um SiPMs showing the greatest increase in
current as a function of dose. Current increases were observed for doses as low
at ~2 rad(Si) for protons and ~20 rad(Si) for electrons. The U.S. Naval
Research Laboratory's (NRL) Strontium Iodide Radiation Instrument (SIRI-1)
experienced a 528 uA increase in the bias current of the on-board 2x2 SensL
J-series 60035 SiPM over its one-year mission in sun-synchronous orbit. The
work here focuses on the increase in bulk current observed with increasing
radiation damage and was performed to better quantify this effect as a function
of dose for future mission. These include the future NRL mission SIRI-2, the
follow on to SIRI-1, Glowbug and the GAGG Radiation Instrument (GARI).
