Performances of a prototype point-contact germanium detector immersed in liquid nitrogen for light dark matter search

TL;DR

This paper reports on the performance and characterization of a germanium detector immersed in liquid nitrogen for light dark matter detection, highlighting improved event discrimination and detector resolution.

Contribution

It introduces an improved bulk/surface event discrimination method and provides detailed characterization of a prototype detector for dark matter search.

Findings

Higher rise-time resolution compared to previous detectors.

Effective discrimination between bulk and surface events.

Consistent results with previous detector spectra in the 0-12 keVee range.

Abstract

The CDEX-10 experiment searches for light weakly-interacting massive particles, a form of dark matter, at the China JinPing underground laboratory, where approximately 10 kg of germanium detectors are arranged in an array and immersed in liquid nitrogen. Herein, we report on the experimental apparatus, detector characterization, and spectrum analysis of one prototype detector. Owing to the higher rise-time resolution of the CDEX-10 prototype detector as compared with CDEX-1B, we identified the origin of an observed category of extremely fast events. For data analysis of the CDEX-10 prototype, we introduced and applied an improved bulk/surface event discrimination method. The results of the new method were compared to those of the CDEX-1B spectrum. Both sets of results showed good consistency in the 0--12 keVee energy range, except for the 8.0 keV K-shell X-ray peak from the external copper.