Study on cosmogenic activation in germanium detectors for future tonne-scale CDEX experiment

TL;DR

This paper evaluates cosmogenic activation in germanium detectors for the CDEX experiment, using simulations validated by experimental data, to predict background levels and explore suppression methods for dark matter and neutrino research.

Contribution

It introduces a validated simulation framework for cosmogenic activation in germanium detectors and predicts background levels for future tonne-scale experiments.

Findings

Validated Geant4 and CRY simulations against experimental spectra.

Predicted cosmogenic background levels for future large-scale detectors.

Proposed underground crystal growth to reduce background.

Abstract

A study on cosmogenic activation in germanium was carried out to evaluate the cosmogenic background level of natural and $^{70}$Ge depleted germanium detectors. The production rates of long-lived radionuclides were calculated with Geant4 and CRY. Results were validated by comparing the simulated and experimental spectra of CDEX-1B detector. Based on the validated codes, the cosmogenic background level was predicted for further tonne-scale CDEX experiment. The suppression of cosmogenic background level could be achieved by underground germanium crystal growth and high-purity germanium detector fabrication to reach the sensitivity requirement for direct detection of dark matter. With the low cosmogenic background, new physics channels, such as solar neutrino research and neutrinoless double-beta decay experiments, were opened and the corresponding simulations and evaluations were carried out.