Speaker
Description
DUNE's Phase-II Far Detector 3 (FD3) will need about 2,000 m² of pTP wavelength-shifting coating for its X-ARAPUCA photon detectors, far beyond what Phase-I in-house deposition can deliver on schedule. We present R&D on outsourcing pTP deposition to an industrial vendor using physical vapor deposition. Coatings on FD2-size substrates reach the 1–2 µm target with less than 10% thickness variation. Their emission spectra match laboratory references, they withstand cryogenic cycling without degradation, and they show a quantum yield of about 59%. An industrially coated filter has also been operated in a DUNE X-ARAPUCA in liquid argon at CIEMAT. Beyond production, simulation shows that an optically smooth pTP film could trap light by total internal reflection in the first layer itself, enabling a single-layer light trap with fewer optical interfaces and higher detection efficiency. We are investigating whether industrial deposition can reach that smoothness. We also outline a QA/QC framework and plans for liquid-argon qualification at BNL.