  The detection of individual photons at cryogenic temperatures is of interest
to many experiments searching for physics beyond the Standard Model. Silicon
photomultipliers are often deployed in liquid argon or liquid xenon to detect
scintillation light by either directly detecting the vacuum ultra-violet
scintillation or by detecting light from fluorescent compounds that are used to
shift the wavelength. Here we present results from an experimental setup that
measures the photon detection efficiencies of silicon photomultipliers,
sensitive to the visible spectrum, at liquid nitrogen temperature, 77 K.
Results from a KETEK PM3325-WB-D0 and a Hamamatsu S13360-3050CS silicon
photomultiplier exhibit a decrease in photon detection efficiency greater than
20% at liquid nitrogen temperature relative to room temperature for 562.5 nm
light.
