Direct Detection of Sub-GeV Dark Matter

TL;DR

This paper explores the potential for direct detection of sub-GeV dark matter particles through electron ionization signals, proposing feasible experimental approaches and analyzing their sensitivity and background challenges.

Contribution

It introduces a new detection method for MeV to GeV dark matter using electron ionization and estimates experimental sensitivities in this unexplored mass range.

Findings

Dark matter-electron scattering rates can be significant for sub-GeV dark matter.

Existing technologies may already probe interesting dark matter models.

Dedicated experiments could greatly improve detection sensitivity.

Abstract

Direct detection strategies are proposed for dark matter particles with MeV to GeV mass. In this largely unexplored mass range, dark matter scattering with electrons can cause single-electron ionization signals, which are detectable with current technology. Ultraviolet photons, individual ions, and heat are interesting alternative signals. Focusing on ionization, we calculate the expected dark matter scattering rates and estimate the sensitivity of possible experiments. Backgrounds that may be relevant are discussed. Theoretically interesting models can be probed with existing technologies, and may even be within reach using ongoing direct detection experiments. Significant improvements in sensitivity should be possible with dedicated experiments, opening up a window to new regions in dark matter parameter space.