Speaker
Description
Coating detector materials with films highly reflective in the vacuum ultraviolet (VUV) region improves sensitivity of the next-generation rare-event detectors that use liquid xenon (LXe). In particular, nEXO requires its Cu field-shaping rings and cathode to be coated by films that are 80% reflective at 175 nm, the mean wavelength of LXe scintillation. Other experiments, like DARWIN, could also benefit from such films. Al-MgF$_2$ coatings are known to be highly reflective in VUV, but depositing Al directly on Cu leads to alloying, decreasing VUV reflectance. Additionally, it was not clear how thin-film coatings would perform on realistic detector components, which are unpolished and passivated. This talk describes dedicated measurements in LXe and gaseous nitrogen of thin-film coatings that were designed to address these issues.
