Evaluation of the Neutron Background in a Direct WIMP Detector with Neutron Veto System Based on Gd-doped Liquid Scintillator

摘要

A direct WIMP (Weakly Interacting Massive Particle) detector with a neutronveto system is designed to better reject neutrons. Two experimentalconfigurations are studied in the present paper: one is for an Xe detectorenclosed in a Gd-loaded scintillator and the other one is for an Xe detectorplaced inside a reactor neutrino detector. The Gd-doped liquid scintillator (orthe neutrino detector) is used as a neutron veto device. The neutronbackgrounds for the two experimental designs have been estimated using Geant4simulations. The results show that the neutron backgrounds can decrease toO(0.1) events per year per tonne of liquid Xenon. We calculate thesensitivities to spin-independent WIMP-nucleon elastic scattering. An exposureof one tonne $\times$ year could reach a cross-section of about6$\times$$10^{-11}$ pb.