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T: Fachverband Teilchenphysik

T 116: Neutrinos Legend, Neutrino Theory

T 116.1: Talk

Thursday, March 23, 2023, 15:50–16:05, POT/0251

Polyethylene-Naphthalate-Based Wavelength Shifting Reflectors for LEGEND-1000 — •Andreas Leonhardt, Maximilian Goldbrunner, and Stefan Schönert for the LEGEND collaboration — Physik Department, Technische Universität München, Garching, Germany

The next-generation experiment LEGEND-1000 will search for the neutrinoless double-beta decay (0νbb) of Ge-76 with unprecedented discovery potential covering the inverted neutrino mass ordering. To this end, 1000 kg of enriched germanium is employed bare in a segmented liquid Argon (LAr) volume. Particle interactions in LAr produce vacuum-ultraviolet (VUV) light flashes peaking at 128 nm, which are converted to longer wavelengths by wavelength shifters (WLSs). To efficiently instrument the LAr volume in LEGEND-1000, a large-scale wavelength shifting reflector (WLSR) based on polyethylene naphthalate (PEN) will be lined on the inner cryostat wall. In this talk, we describe the custom VUV spectrofluorometer used for the optical characterization of PEN-based WLSRs at VUV excitation and cryogenic temperatures. We present the first measurement of the wavelength-resolved photoluminescence yield of PEN for VUV excitation at cryogenic temperatures and compare it to the commonly used wavelength shifter tetraphenyl butadiene (TPB). This research is supported by the DFG through the Excellence Cluster ORIGINS and the SFB1258.