Scintillation of Liquid Helium for Low-Energy Nuclear Recoils

TL;DR

This paper investigates the scintillation response of liquid helium to low-energy nuclear recoils, suggesting its potential as a dark matter detector due to higher-than-expected scintillation yields.

Contribution

It provides new measurements of liquid helium scintillation yields for low-energy recoils and compares these with electron responses, informing detector development.

Findings

Prompt scintillation yield is higher than linear extrapolation predicts.

Recoil and electron responses differ in scintillation and charge separation.

Liquid helium shows promise as a dark matter detection medium.

Abstract

The scintillation properties of liquid helium upon the recoil of a low energy helium atom are discussed in the context of the possible use of this medium as a detector of dark matter. It is found that the prompt scintillation yield in the range of recoil energies from a few keV to 100 keV is somewhat higher than that obtained by a linear extrapolation from the measured yield for an 5 MeV alpha particle. A comparison is made of both the scintillation yield and the charge separation by an electric field for nuclear recoils and for electrons stopped in helium.