Scintillation Pulse Shape Discrimination in a Two-Phase Xenon Time Projection Chamber

TL;DR

This study investigates pulse shape discrimination in a two-phase xenon detector, demonstrating combined methods to improve background rejection and exploring its potential for detecting higher energy WIMP recoils.

Contribution

It introduces a combined pulse shape and charge-to-light ratio technique in a two-phase xenon TPC and analyzes its performance across different energies and electric fields.

Findings

Combined discrimination reduces leakage below individual methods.

Pulse shape discrimination is statistically limited at low energies.

Potential for detecting higher energy inelastic WIMP recoils.

Abstract

The energy and electric field dependence of pulse shape discrimination in liquid xenon have been measured in a 10 gm two-phase xenon time projection chamber. We have demonstrated the use of the pulse shape and charge-to-light ratio simultaneously to obtain a leakage below that achievable by either discriminant alone. A Monte Carlo is used to show that the dominant fluctuation in the pulse shape quantity is statistical in nature, and project the performance of these techniques in larger detectors. Although the performance is generally weak at low energies relevant to elastic WIMP recoil searches, the pulse shape can be used in probing for higher energy inelastic WIMP recoils.