Limits on light WIMPs with a 1 kg-scale germanium detector at 160 eVee physics threshold at the China Jinping Underground Laboratory

TL;DR

This paper presents new constraints on light WIMP dark matter using a 1 kg germanium detector with a 160 eVee threshold at CJPL, extending sensitivity down to 2 GeV WIMPs and improving previous bounds.

Contribution

First constraints on light WIMPs with a germanium detector at a 160 eVee threshold, enhancing the lower mass sensitivity and setting new limits at 2 GeV.

Findings

Extended WIMP mass sensitivity down to 2 GeV

Improved bounds on WIMP-nucleon interactions below 6 GeV

Demonstrated the effectiveness of low-threshold germanium detectors

Abstract

We report results of a search for light weakly interacting massive particle (WIMP) dark matter from the CDEX-1 experiment at the China Jinping Underground Laboratory (CJPL). Constraints on WIMP-nucleon spin-independent (SI) and spin-dependent (SD) couplings are derived with a physics threshold of 160 eVee, from an exposure of 737.1 kg-days. The SI and SD limits extend the lower reach of light WIMPs to 2 GeV and improve over our earlier bounds at WIMP mass less than 6 GeV.