Results of direct dark matter detection with CDEX experiment at CJPL

TL;DR

The CDEX experiment at CJPL searches for light WIMPs using germanium detectors with low energy thresholds, setting new limits on WIMP interactions and exploring effects like Migdal, with future plans for expanded detection capabilities.

Contribution

This paper reports new results from CDEX detectors with low energy thresholds, including re-analysis incorporating Migdal effect and plans for larger future detectors.

Findings

Set new limits on light WIMP-nucleus interactions.

Achieved an energy threshold of 160 eV for detection.

Re-analyzed data considering Migdal effect for sub-GeV WIMPs.

Abstract

The China Dark Matter Experiment (CDEX), located at the China Jinping Underground Laboratory (CJPL) whose overburden is about 2400m rock, aims at direct searches of light Weakly Interacting Massive Particles (WIMPs). A single-element 994-gram p-type point contact (PPC) germanium detector (CDEX-1B) runs inside a solid passive shielding system. To achieve lower background, a prototype 10kg PPC germanium detector array (CDEX-10), consisting of three detector strings with three germanium crystals each, is directly immersed in the liquid nitrogen. With the energy threshold of 160eV, the limits on WIMP-nucleus scattering are set by energy spectra and annual modulation analysis, respectively. Incorporating Migdal effect, the data of CDEX-1B are re-analyzed to search sub-GeV WIMPs. Finally, the future plan of CDEX experiment in CJPL-II is introduced.