Limits on Low-Mass WIMP Dark Matter with an Ultra-Low-Energy Germanium Detector at 220 eV Threshold

TL;DR

This study demonstrates a highly sensitive germanium detector with a 220 eV threshold that sets new constraints on low-mass WIMP dark matter, opening new avenues for sub-keV energy experiments.

Contribution

The paper introduces an ultra-low-energy germanium detector achieving a 220 eV threshold, enabling improved constraints on low-mass WIMPs below 10 GeV.

Findings

Constraints on WIMPs between 3-6 GeV improved over previous results.

Detector achieves 50% efficiency at 220 eV energy threshold.

Projected sensitivities for future experiments indicate promising potential.

Abstract

An energy threshold of (220$\pm$10) eV was achieved at an efficiency of 50% with a four-channel ultra-low-energy germanium detector each with an active mass of 5 g\cite{wimppaper}. This provides a unique probe to WIMP dark matter with mass below 10 GeV. With low background data taken at the Kuo-Sheng Laboratory, constraints on WIMPs in the galactic halo were derived. Both spin-independent WIMP-nucleon and spin-dependent WIMP-neutron bounds improve over previous results for WIMP mass between 3$-$6 GeV. These results, together with those on spin-dependent couplings, will be presented. Sensitivities for full-scale experiments were projected. This detector technique makes the unexplored sub-keV energy window accessible for new neutrino and dark matter experiments.