Results on low mass WIMPs using an upgraded CRESST-II detector

TL;DR

This paper reports on a low-threshold analysis using an upgraded CRESST-II detector, setting new limits on low-mass WIMPs below 3 GeV/c^2 and clarifying previous potential excess signals.

Contribution

It introduces an improved detector module with effective background vetoing, enabling exploration of previously inaccessible low-mass WIMP parameter space.

Findings

Set new limits on WIMP-nucleon cross-section for masses below 3 GeV/c^2

Did not confirm previous excess signals from earlier data

Demonstrated the detector's capability to probe low-mass WIMPs

Abstract

The CRESST-II cryogenic dark matter search aims for the detection of WIMPs via elastic scattering off nuclei in CaWO$_4$ crystals. We present results from a low-threshold analysis of a single upgraded detector module. This module efficiently vetoes low energy backgrounds induced by $\alpha$-decays on inner surfaces of the detector. With an exposure of \unit[29.35]{kg live days} collected in 2013 we set a limit on spin-independent WIMP-nucleon scattering which probes a new region of parameter space for WIMP masses below \unit[3]{GeV/c$^2$}, previously not covered in direct detection searches. A possible excess over background discussed for the previous CRESST-II phase 1 (from 2009 to 2011) is not confirmed.