Measurement of photoelectron yield of the prototype for the CDEX-10 liquid argon detector

TL;DR

This paper reports the measurement of photoelectron yield in a liquid argon prototype for the CDEX-10 dark matter detector, providing key parameters for optimizing detector performance.

Contribution

It presents the first detailed measurement and simulation validation of photoelectron yield in a liquid argon prototype for dark matter detection.

Findings

Photoelectron yield measured as 0.051-0.079 p.e./keV at 662 keV

Good agreement between experimental data and simulations

Determined key parameters like argon excimer survival fraction and photon absorption length

Abstract

The China Dark Matter Experiment (CDEX) is a low background experiment at China Jinping Underground Laboratory (CJPL) designed to directly detect dark matter with a high-purity Germanium (HPGe) detector. In the second phase CDEX-10 with a 10 kg Germanium array detector system, the liquid argon (LAr) anti-compton active shielding and cooling system is proposed. For purpose of studying the properties of LAr detector, a prototype with an active volume of 7 liters of liquid argon was built and operated. The photoelectron yields, as a critically important parameter for the prototype detector, have been measured to be 0.051-0.079 p.e./keV for 662 keV Gamma lines at different positions. The good agreement between the experimental and simulation results has provided a quite reasonable understanding and determination of the important parameters such as the Surviving Fraction of the Ar2 excimers, the absorption length for 128 nm photons in liquid argon, the reflectivity of Teflon and so on.