Measurements of electron transport in liquid and gas Xenon using a laser-driven photocathode

TL;DR

This study measures electron drift velocities, diffusion, and photocathode efficiency in liquid and gaseous xenon using laser-induced photoemission, providing critical data for the development of large-scale noble liquid detectors.

Contribution

It introduces a laser-driven photocathode method to accurately measure electron transport properties in xenon in both liquid and gas phases, advancing detector calibration techniques.

Findings

Electron drift velocities are 1.97 mm/μs in liquid and 1.42 mm/μs in gas at 0.5 kV/cm.

Longitudinal diffusion coefficients are 25.7 cm²/s in liquid and 149 cm²/s in gas.

Quantum efficiency of gold photocathodes varies with environment and photon energy.

Abstract

Measurements of electron drift properties in liquid and gaseous xenon are reported. The electrons are generated by the photoelectric effect in a semi-transparent gold photocathode driven in transmission mode with a pulsed ultraviolet laser. The charges drift and diffuse in a small chamber at various electric fields and a fixed drift distance of 2.0 cm. At an electric field of 0.5 kV/cm, the measured drift velocities and corresponding temperature coefficients respectively are $1.97 \pm 0.04$ mm/$\mu$s and $(-0.69\pm0.05)$\%/K for liquid xenon, and $1.42 \pm 0.03$ mm/$\mu$s and $(+0.11\pm0.01)$\%/K for gaseous xenon at 1.5 bar. In addition, we measure longitudinal diffusion coefficients of $25.7 \pm 4.6$ cm$^2$/s and $149 \pm 23$ cm$^2$/s, for liquid and gas, respectively. The quantum efficiency of the gold photocathode is studied at the photon energy of 4.73 eV in liquid and gaseous xenon, and vacuum. These charge transport properties and the behavior of photocathodes in a xenon environment are important in designing and calibrating future large scale noble liquid detectors.