A search for low-mass WIMPs with EDELWEISS-II heat-and-ionization detectors

TL;DR

This paper reports on a search for low-mass WIMPs using EDELWEISS-II detectors, finding no evidence of WIMP signals and setting new limits on WIMP-nucleon cross-sections that challenge some previous experimental claims.

Contribution

It introduces an improved germanium detector design and provides new constraints on low-mass WIMP interactions based on 113 kg·days of data.

Findings

No evidence for WIMP-induced nuclear recoils was observed.

Set a 90% CL limit of 1.0x10^-5 pb on WIMP-nucleon cross-section for 10 GeV WIMPs.

Constraints challenge previous signals reported by CoGeNT, DAMA, and CRESST.

Abstract

We report on a search for low-energy (E < 20 keV) WIMP-induced nuclear recoils using data collected in 2009 - 2010 by EDELWEISS from four germanium detectors equipped with thermal sensors and an electrode design (ID) which allows to efficiently reject several sources of background. The data indicate no evidence for an exponential distribution of low-energy nuclear recoils that could be attributed to WIMP elastic scattering after an exposure of 113 kg.d. For WIMPs of mass 10 GeV, the observation of one event in the WIMP search region results in a 90% CL limit of 1.0x10^-5 pb on the spin-independent WIMP-nucleon scattering cross-section, which constrains the parameter space associated with the findings reported by the CoGeNT, DAMA and CRESST experiments.