The neutron background of the XENON100 dark matter experiment

TL;DR

This paper analyzes neutron backgrounds in the XENON100 dark matter detector, using simulations and measurements to estimate their impact on WIMP search sensitivity, finding backgrounds are not limiting the experiment's sensitivity.

Contribution

It provides a detailed Monte Carlo simulation-based estimate of neutron backgrounds from various sources in the XENON100 detector, improving understanding of background levels for dark matter searches.

Findings

Predicted neutron background events are low and do not limit sensitivity.

Neutron backgrounds from ($ extalpha$,n) reactions, fission, and muons are quantified.

Background estimates align with observed data from 2011 and 2012.

Abstract

The XENON100 experiment, installed underground at the Laboratori Nazionali del Gran Sasso (LNGS), aims to directly detect dark matter in the form of Weakly Interacting Massive Particles (WIMPs) via their elastic scattering off xenon nuclei. This paper presents a study on the nuclear recoil background of the experiment, taking into account neutron backgrounds from ($\alpha$,n) and spontaneous fission reactions due to natural radioactivity in the detector and shield materials, as well as muon-induced neutrons. Based on Monte Carlo simulations and using measured radioactive contaminations of all detector components, we predict the nuclear recoil backgrounds for the WIMP search results published by the XENON100 experiment in 2011 and 2012, 0.11$^{+0.08}_{-0.04}$ events and 0.17$^{+0.12}_{-0.07}$ events, respectively, and conclude that they do not limit the sensitivity of the experiment.