The CDEX-1 1 kg Point-Contact Germanium Detector for Low Mass Dark Matter Searches

TL;DR

This paper reports on the development and testing of a 1 kg point-contact germanium detector with sub-keV energy threshold, designed for low mass dark matter searches in underground laboratories.

Contribution

Introduction of a novel 1 kg germanium detector with dual-electrode readout enabling low energy threshold detection for dark matter experiments.

Findings

Detector achieves sub-keV energy threshold.

System demonstrates stable operation and good energy resolution.

Potential for improved signal discrimination in dark matter detection.

Abstract

The CDEX Collaboration has been established for direct detection of light dark matter particles, using ultra-low energy threshold p-type point-contact germanium detectors, in China JinPing underground Laboratory (CJPL). The first 1 kg point-contact germanium detector with a sub-keV energy threshold has been tested in a passive shielding system located in CJPL. The outputs from both the point-contact p+ electrode and the outside n+ electrode make it possible to scan the lower energy range of less than 1 keV and at the same time to detect the higher energy range up to 3 MeV. The outputs from both p+ and n+ electrode may also provide a more powerful method for signal discrimination for dark matter experiment. Some key parameters, including energy resolution, dead time, decay times of internal X-rays, and system stability, have been tested and measured. The results show that the 1 kg point-contact germanium detector, together with its shielding system and electronics, can run smoothly with good performances. This detector system will be deployed for dark matter search experiments.