Measurement of the Drift Velocity and Transverse Diffusion of Electrons in Liquid Xenon with the EXO-200 Detector

TL;DR

This paper reports precise measurements of electron drift velocity and transverse diffusion in liquid xenon, crucial for improving event discrimination in the EXO-200 neutrinoless double beta decay experiment.

Contribution

It provides the first detailed measurements of electron transport properties in liquid xenon across a range of electric fields relevant for detector operation.

Findings

Drift velocity at 380 V/cm is 1.705 mm/μs.

Transverse diffusion coefficient at 380 V/cm is 55 cm²/s.

Transport properties vary with electric field, informing detector modeling.

Abstract

The EXO-200 Collaboration is searching for neutrinoless double beta decay using a liquid xenon (LXe) time projection chamber. This measurement relies on modeling the transport of charge deposits produced by interactions in the LXe to allow discrimination between signal and background events. Here we present measurements of the transverse diffusion constant and drift velocity of electrons at drift fields between 20~V/cm and 615~V/cm using EXO-200 data. At the operating field of 380~V/cm EXO-200 measures a drift velocity of 1.705$_{-0.010}^{+0.014}$~mm/$\mu$s and a transverse diffusion coefficient of 55$\pm$4~cm$^2$/s.