QUEST-DMC superfluid $^3$He detector for sub-GeV dark matter

TL;DR

This paper proposes a novel superfluid helium-3 detector for sub-GeV dark matter, capable of detecting low-energy nuclear recoils, and models its response and sensitivity to explore new dark matter parameter space.

Contribution

It introduces a new detector concept using superfluid helium-3 and develops a response model and sensitivity analysis for light dark matter detection.

Findings

Projected sub-eV energy threshold enables detection of light dark matter

Simulated detector response to dark matter signals and backgrounds

Sensitivity analysis shows potential to explore new parameter space

Abstract

The focus of dark matter searches to date has been on Weakly Interacting Massive Particles (WIMPs) in the GeV/$c^2$-TeV/$c^2$ mass range. The direct, indirect and collider searches in this mass range have been extensive but ultimately unsuccessful, providing a strong motivation for widening the search outside this range. Here we describe a new concept for a dark matter experiment, employing superfluid $^3$He as a detector for dark matter that is close to the mass of the proton, of order 1 GeV/$c^2$. The QUEST-DMC detector concept is based on quasiparticle detection in a bolometer cell by a nanomechanical resonator. In this paper we develop the energy measurement methodology and detector response model, simulate candidate dark matter signals and expected background interactions, and calculate the sensitivity of such a detector. We project that such a detector can reach sub-eV nuclear recoil energy threshold, opening up new windows on the parameter space of both spin-dependent and spin-independent interactions of light dark matter candidates.