Evaluation of the neutron background in cryogenic Germanium target for WIMP direct detection when using a reactor neutrino detector as a neutron veto system

TL;DR

This paper evaluates how effectively a reactor neutrino detector can serve as a neutron veto in a cryogenic Germanium WIMP detector, significantly reducing neutron background and improving sensitivity to dark matter interactions.

Contribution

It introduces a novel experimental setup combining cryogenic Germanium detectors with a reactor neutrino detector as a neutron veto, and estimates the resulting background reduction and sensitivity.

Findings

Neutron background can be reduced to approximately 0.01 events per year per tonne.

The setup can achieve a sensitivity to WIMP-nucleon cross-section of about 2×10^{-11} pb.

The neutron veto system significantly enhances the detector's ability to discriminate against background.

Abstract

A direct WIMP (Weakly Interacting Massive Particle) detector with a neutron veto system is designed to better reject neutrons. An experimental configuration is studied in the present paper: 984 Ge modules are placed inside a reactor neutrino detector. In order to discriminate between nuclear and electron recoil, both ionization and heat signatures are measured using cryogenic germanium detectors in this detection. The neutrino detector is used as a neutron veto device.The neutron background for the experimental design has been estimated using the Geant4 simulation. The results show that the neutron background can decrease to O(0.01) events per year per tonne of high purity Germanium. We calculate the sensitivity to spin-independent WIMP-nucleon elastic scattering. An exposure of one tonne $\times$ year could reach a cross-section of about 2$\times$$10^{-11}$ pb.