Speaker
Description
Efficient detection of 178 nm vacuum ultraviolet (VUV) scintillation light is essential for next-generation xenon-based rare-event detectors. One such detector is nEXO, a 5-tonne liquid xenon (LXe) time-projection chamber enriched to 90% Xe-136, designed to search for neutrinoless double beta (0νββ) decay with a projected half-life sensitivity of 1.35×10²⁸ years over a 10-year lifespan. Achieving this sensitivity requires excellent collection of scintillation light and accurate modeling of the detector's VUV optics. This motivates a rigorous characterization of silicon photomultiplier (SiPM) light sensors, and of the optical properties of detector materials. We operate a small, optically simple cryogenic cell at UMass Amherst used to study light collection in LXe. The setup is equipped with a Fondazione Bruno Kessler HD3 VUV SiPM and an Am-241 alpha source. We present results from optical measurements of amorphous silicon reflectors, along with long-term SiPM characterization and a new method for measuring correlated avalanches.