Characterization of Silicon Photomultiplier Photon Detection Efficiency under Variable Wavelengths

Silicon photomultipliers (SiPMs) are commonly used in rare event searches to detect photons in scintillation detectors, often comprised of 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, the PDE is well documented at room temperature; however, recent work suggests that the PDE may decrease at cryogenic temperatures. The purpose of these measurements is to characterize the wavelength dependence of the PDE at multiple 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 with 385nm, 470nm, and 740nm LEDs; results from the study show that photon detection efficiency was greatest at 470nm and decreased for both the higher and lower wavelengths tested. Plans for future measurements at liquid nitrogen temperature will also be discussed.