Speaker
Description
Next-generation noble-element experiments in neutrino and dark matter physics will need photodetector systems with vacuum ultraviolet (VUV) sensitivity covering thousands of square meters. Vacuum deposition is the current standard for wavelength-shifting (WLS) coatings, but its throughput, labor cost, and chamber size limits make it hard to scale to that level. Solvent-based coating offers a scalable alternative.
In this talk, I present an efficient, cost-effective solvent spray-coating technique for depositing para-terphenyl (pTP) on UV-transparent acrylic substrates. The acrylic substrate and the solvent are selected based on UV transparency, cryogenic robustness, and pTP solubility. The pTP solution is deposited with a commercial airbrush whose spray parameters control the coating quality. The coatings are characterized with complementary methods: white-light interferometry for thickness and roughness, UV transmission scans at 340 nm for uniformity, liquid-nitrogen thermal cycling for adhesion and stability, and a dedicated VUV spectroscopy setup for WLS efficiency across the 115–200 nm range. I conclude with ongoing work on solvent optimization, binder materials to improve adhesion to the substrate, and an automated spraying system for reproducibility.