[en] For rare event searches, such as the direct dark matter search experiment CRESST (Cryogenic Rare Event Search with Superconducting Thermometers), highly sensitive temperature sensors and cryogenic detectors are indispensable. A very low energy threshold ($\ll <!--\; ???\; -->$ 100 eV) and good energy resolution is required to increase the experimental sensitivity particularly for low mass dark matter particles ($m_{DM}$ < 5 GeV/c${}^2$) and to differentiate between these rare events and other particle interactions such as, e.g., radioactive backgrounds. In this contribution we present an overview of the various facilities and techniques available at TUM which are necessary for the production, development and improvement of low temperature detectors and temperature sensors. We also explain the methods we employ for the study and characterization of such technology and the potential applications. In addition, we discuss the quality requirements imposed on the developed systems.

[en] The Physics Department of the TUM operates a shallow underground detector laboratory (UGL) in Garching, Germany. It provides $\sim <!--\; ???\; -->$ 160 m${}^2$ of laboratory space which is shielded from cosmic radiation by $\sim <!--\; ???\; -->$ 6 m of gravel and soil, corresponding to $\sim <!--\; ???\; -->$ 15 m.w.e.. The laboratory houses a cleanroom (class ISO 7) equipped for fabrication and assembly of cryogenic detectors. Furthermore, the UGL runs a ${}^3$He-${}^4$He dilution refrigerator. The infrastructure is particularly relevant for the characterization of CaWO${}_4$ target crystals for the CRESST-III experiment, detector fabrication and detector assembly for rare event searches. Future applications include detector development in the framework of coherent neutrino nucleus scattering experiments ($\mathrm{\nu <!--\; ??\; -->}$-cleus) and studying its potential as a site to search for MeV-scale Dark Matter with gram-scale cryogenic detectors.

[en] The direct dark matter search experiment CRESST uses scintillating CaWO${}_4$ single crystals as targets for possible recoils of dark matter particles. For several years these CaWO${}_4$ crystals are produced directly at TUM including the CaWO${}_4$ powder production from the raw materials CaCO${}_3$ and WO${}_3$ as well as the crystal growth via the Czochralski method. To further increase the sensitivity of the CRESST experiment, an improvement of the crystal radiopurity is crucial. To achieve this goal, a new method for the chemical purification of the raw materials has been developed at TUM. In order to investigate the radiopurity-level achieved by this method, highly-sensitive screening methods are required. In this work Accelerator Mass Spectrometry (AMS) has been tested for CaWO${}_4$ radiopurity screening and first results will be presented.

[en] The development of low-threshold detectors for the study of coherent elastic neutrino-nucleus scattering and for the search for light dark matter necessitates methods of low-energy calibration. We suggest this can be provided by the nuclear recoils resulting from the γ emission following thermal neutron capture. In particular, several MeV-scale single-γ transitions induce well-defined nuclear recoil peaks in the 100 eV range. Using the FIFRELIN code, complete schemes of γ-cascades for various isotopes can be predicted with high accuracy to determine the continuous background of nuclear recoils below the calibration peaks. We present a comprehensive experimental concept for the calibration of CaWO₄ and Ge cryogenic detectors at a research reactor. For CaWO₄ the simulations show that two nuclear recoil peaks at 112.5 eV and 160.3 eV should be visible above background simply in the spectrum of the cryogenic detector. Then we discuss how the additional tagging for the associated γ increases the sensitivity of the method and extends its application to a wider energy range and to Ge cryogenic detectors. (paper)

[en] 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 $\sim <!--\; ???\; -->15\mathrm{m}.\mathrm{w}.\mathrm{e}.$. 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 $\le <!--\; ???\; -->12-<!--\; ???\; -->14\mathrm{m}\mathrm{K}$. The infrastructure provided by the shallow laboratory is particularly relevant for the characterization of ${\text{CaWO}}_4$ 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 ($\mathrm{\nu <!--\; ??\; -->}$-cleus) and studying its potential as a site to search for MeV-scale dark matter with gram-scale cryogenic detectors.