Observation of Long-Lived UV-Induced Fluorescence from Environmental Materials Using the HVeV Detector as Developed for SuperCDMS

We describe recent experiments using a SuperCDMS high-voltage single-charge sensitive (HVeV) detector illuminated with an ultraviolet LED (275 nm) and a monochromatic laser (650 nm) using a dual-fiber optic system installed in a small dilution refrigerator at Stanford University. We observed a population of fluorescence background events after UV exposure but not after exposure to the laser source. The fluorescence was likely due to scattered UV photons absorbed outside the detector. We discuss the possibility of fluorescence being a contributor to the low energy excess background observed in above-ground Dark Matter experiments.