Composite CaWO4 Detectors for the CRESST-II Experiment

TL;DR

This paper reports on the first use of composite CaWO4 detectors in the CRESST-II dark matter search, showing potential improvements in light yield and event discrimination for cryogenic WIMP detection.

Contribution

It introduces composite CaWO4 detectors with glued thermometers, offering a new approach to improve light output and event discrimination in dark matter experiments.

Findings

Composite detectors produce higher light yields.

Potential for enhanced event discrimination.

Successful initial testing in Gran Sasso setup.

Abstract

CRESST-II, standing for Cryogenic Rare Events Search with Superconducting Thermometers phase II, is an experiment searching for Dark Matter. In the LNGS facility in Gran Sasso, Italy, a cryogenic detector setup is operated in order to detect WIMPs by elastic scattering off nuclei, generating phononic lattice excitations and scintillation light. The thermometers used in the experiment consist of a tungsten thin-film structure evaporated onto the CaWO4 absorber crystal. The process of evaporation causes a decrease in the scintillation light output. This, together with the need of a big-scale detector production for the upcoming EURECA experiment lead to investigations for producing thermometers on smaller crystals which are glued onto the absorber crystal. In our Run 31 we tested composite detectors for the first time in the Gran Sasso setup. They seem to produce higher light yields as hoped and could provide an additional time based discrimination mechanism for low light yield clamp events.