Directly detecting sub-GeV dark matter with electrons from nuclear scattering

TL;DR

This paper proposes a novel detection method for sub-GeV dark matter by observing electrons from nuclear scattering, significantly improving detection sensitivity and setting new experimental limits.

Contribution

It introduces a new detection technique that leverages ionization electrons from nuclear recoils, enhancing sensitivity to light dark matter particles.

Findings

Existing experiments set new leading limits.

Future experiments could probe thermal freeze-out cross sections.

Including electron detection greatly improves sensitivity.

Abstract

Dark matter (DM) particles with mass in the sub-GeV range are an attractive alternative to heavier weakly-interacting massive particles, but direct detection of such light particles is challenging. If however DM-nucleus scattering leads to ionisation of the recoiling atom, the resulting electron may be detected even if the nuclear recoil is unobservable. We demonstrate that including this effect significantly enhances direct detection sensitivity to sub-GeV DM. Existing experiments set world-leading limits, and future experiments may probe the cross sections relevant for thermal freeze-out.