Signatures and Detection Prospects for sub-GeV Dark Matter with Superfluid Helium

TL;DR

This paper investigates using superfluid helium as a detector for sub-GeV dark matter, modeling the interaction processes and proposing a novel detection method with NEMS sensors to improve sensitivity.

Contribution

It introduces a detailed analytical framework for DM interactions in superfluid helium and proposes a new detection approach using force-sensitive nanoelectromechanical devices.

Findings

Modeling of atomic cascade and quasi-particle emission in helium

Proposal of NEMS-based detection method for sub-GeV dark matter

Sensitivity projections for future experiments

Abstract

We explore the possibility of using superfluid helium for direct detection of sub-GeV dark matter (DM). We discuss the relevant phenomenology resulting from the scattering of an incident dark matter particle on a Helium nucleus. Rather than directly exciting quasi-particles, DM in this mass range will interact with a single He atom, triggering an atomic cascade which eventually also includes emission and thermalization of quasi-particles. We present in detail the analytical framework needed for modeling these processes and determining the resulting flux of quasi-particles. We propose a novel method for detecting this flux with modern force-sensitive devices, such as nanoelectro-mechanical system (NEMS) oscillators, and derive the sensitivity projections for a generic sub-GeV DM detection experiment using such sensors.