Heidelberg 2022 – scientific programme

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T: Fachverband Teilchenphysik

T 78: Experimental Techniques in Astroparticle Physics 3

T 78.5: Talk

Wednesday, March 23, 2022, 17:15–17:30, T-H37

Characterization of Wavelength Shifters for LAr Instrumentation Using VUV Spectrofluorometry — •Andreas Leonhardt¹, Gabriela R. Araujo², Patrick Krause¹, Laszlo Papp¹, Tina R. Pollmann³, and Stefan Schönert¹ — ¹Physik Department, Technische Universität München, Garching, Germany — ²Physik-Institut, Universität Zürich, Zurich, Switzerland — ³Nikhef National Institute for Subatomic Physic, Amsterdam, Netherlands

Experiments searching for dark matter or neutrinoless double-beta decay commonly use liquid argon (LAr) as a target or instrumented shielding medium. Particle interactions in the LAr produce vacuum-ultraviolet (VUV) light flashes peaking at 128 nm, which are converted to longer wavelengths by wavelength shifters (WLSs). Due to the short LAr scintillation wavelength and low LAr temperature, the characterization of WLSs requires VUV optics and a cooling system in vacuum. We present the developed custom spectrofluorometer, which enables us to characterize WLSs at VUV excitation and low temperatures. The setup consists of a high-intensity deuterium light source coupled to a VUV monochromator and a vacuum-tight sample chamber. The wavelength shifting material can be mounted on a cryocooler coldhead to measure the wavelength-resolved and wavelength-integrated photoluminescence light yield at the relevant LAr temperature. We describe the characterization campaign of the wavelength-shifting reflector of the LEGEND-200 experiment with the VUV spectrofluorometer and summarize the results. This research is supported by the DFG through the Excellence Cluster ORIGINS and the SFB1258.