A Cryogenic Detector Characterization Facility in the Shallow Underground Laboratory at the Technical University of Munich

Abstract

The Physics Department of the Technical University of Munich operates a shallow underground detector laboratory in Garching, Germany. It provides \(\sim 160\,{\mathrm{m}^2}\) of laboratory space which is shielded from cosmic radiation by \(\sim 6\,\mathrm{m}\) of gravel and soil, corresponding to a shielding of \(\sim 15\,{\mathrm{m.w.e.}}\). The laboratory also houses a cleanroom equipped with work- and wetbenches, a chemical fumehood as well as a spin-coater and a mask-aligner for photolithographic processing of semiconductor detectors. Furthermore, the shallow underground laboratory runs two high-purity germanium detector screening stations, a liquid argon cryostat and a \(^3\)He–\(^4\)He dilution refrigerator with a base temperature of \(\le 12-14\,\mathrm{mK}\). The infrastructure provided by the shallow laboratory is particularly relevant for the characterization of \(\hbox {CaWO}_4\) target crystals for the CRESST-III experiment, detector fabrication and assembly for rare event searches. Future applications of the laboratory include detector development in the framework of coherent neutrino nucleus scattering experiments (\(\nu \)-cleus) and studying its potential as a site to search for MeV-scale dark matter with gram-scale cryogenic detectors.