Characterization of Silicon Photomultiplier Photon Detection Efficiency for Variable Wavelength at Liquid Nitrogen Temperature*

Silicon photomultipliers (SiPMs) are commonly used in rare event searches to detect photons in scintillation detectors, often deployed in cryogenic liquids such as argon or xenon. The photon detection efficiency (PDE) of these cryogenically operated SiPMs should be as large as possible to maximize light yield in the experiment. Currently, PDE is well documented at room temperature; however, recent work suggests that PDE decreases at cryogenic temperatures. The purpose of these measurements is to characterize the wavelength dependence of the PDE at temperatures in order to improve understanding of the observed decrease in PDE at low temperatures. Two silicon photomultipliers, a BROADCOM AFBRS4K33C0135L and a Hamamatsu S13360-3050C, were tested at room temperature and liquid nitrogen temperature, 77K, with 385 nm, 470 nm, and 740 nm LEDs.