Measurement of light and charge yield of low-energy electronic recoils in liquid xenon

TL;DR

This study precisely measures how light and charge yields in liquid xenon vary with electric field and low-energy recoils, providing critical data for dark matter detection at energies below 10 keV.

Contribution

It presents the first high-precision measurements of light and charge yields at recoil energies down to 1 keV in liquid xenon, revealing new behaviors at very low energies.

Findings

Charge and light yields are anti-correlated above 3 keV.

Field dependence of yields becomes negligible below 6 keV.

Charge yield is higher than expected below 3 keV, with non-linear energy reconstruction.

Abstract

The dependence of the light and charge yield of liquid xenon on the applied electric field and recoil energy is important for dark matter detectors using liquid xenon time projections chambers. Few measurements have been made of this field dependence at recoil energies less than 10 keV. In this paper we present results of such measurements using a specialized detector. Recoil energies are determined via the Compton coincidence technique at four drift fields relevant for liquid xenon dark matter detectors: 0.19, 0.48, 1.02, and 2.32 kV/cm. Mean recoil energies down to 1 keV were measured with unprecedented precision. We find that the charge and light yield are anti-correlated above 3 keV, and that the field dependence becomes negligible below 6 keV. However, below 3 keV we find a charge yield significantly higher than expectation and a reconstructed energy deviating from linearity.