Search for inelastic WIMP nucleus scattering on 129Xe in data from the XMASS-I experiment

Abstract

A search for inelastic scattering of weakly interacting massive particles (WIMPs) on the isotope 129Xewas done in data taken with the single-phase liquid-xenon detectorXMASSat the Kamioka Observatory. Using a restricted volume containing 41 kg of liquid xenon at the very center of our detector, we observed no significant excess of events in 165.9 live days of data. Our background reduction allowed us to derive our limits without explicitly subtracting the remaining events that are compatible with background expectations. As an example, we derive for a 50 GeV WIMP an upper limit of 3.2 pb at the 90% confidence level for its inelastic cross section on 129Xe nuclei.