  Silicon photomultipliers (SiPMs) have become popular light conversion devices
in recent years due to their low bias voltage and sensitivity to wavelengths
emitted from common scintillating materials. These properties make them
particularly attractive for resource-constrained missions such as space-based
detector applications. However the space radiation environment is known to be
particularly harsh on semiconductor devices, where high particle fluences can
degrade performance over time. The radiation hardness of a particular SiPM,
manufactured by ON Semiconductor (formally SensL), has yet to be studied with
high energy protons, which are native to the space radiation environment. To
study these effects we have irradiated groups of two SiPMs to four different
fluences of 800 MeV protons delivered by the accelerator at the Los Alamos
Neutron Science Center. Fluences of $1.68\times10^{9}$, $1.73\times10^{10}$,
$6.91\times10^{10}$, and $1.73\times10^{11}$ protons cm$^{-2}$, and their
corresponding estimated doses of $0.15$, $1.55$, $6.19$, and $15.5$ kRad, were
chosen based on estimates of the potential exposure a SiPM might receive during
an interplanetary space mission lasting 10 years. We report the effects these
doses have on dark current and the self-annealing time.
