A direct dark matter search in XMASS-I

TL;DR

This paper reports a direct search for dark matter WIMPs using a liquid xenon detector at Kamioka, setting the most stringent upper limit on the WIMP-nucleon cross section among single-phase xenon detectors.

Contribution

First to conduct a long-term dark matter search with a single-phase liquid xenon detector at Kamioka, providing new upper limits on WIMP interactions.

Findings

No excess events observed above background.

Set an upper limit of 2.2 x 10^-44 cm^2 on WIMP-nucleon cross section.

Achieved the most stringent limit among similar detectors.

Abstract

A search for dark matter using an underground single-phase liquid xenon detector was conducted at the Kamioka Observatory in Japan, particularly for Weakly Interacting Massive Particles (WIMPs). We have used 705.9 live days of data in a fiducial volume containing 97 kg of liquid xenon at the center of the detector. The event rate in the fiducial volume after the data reduction was ${\rm (4.2 \pm 0.2) \times 10^{-3} \, day^{-1}kg^{-1} keV_{ee}^{-1}}$ at ${\rm 5 \, keV_{ee}}$, with a signal efficiency of ${\rm 20\%}$. All the remaining events are consistent with our background evaluation, mostly of the "mis-reconstructed events" originated from $^{210}$Pb in the copper plates lining the detector's inner surface. The obtained upper limit on a spin-independent WIMP-nucleon cross section was ${\rm 2.2 \times 10^{-44} \, cm^{2}}$ for a WIMP mass of ${\rm 60 \, GeV/c^{2}}$ at the $90\%$ confidence level, which was the most stringent limit among results from single-phase liquid xenon detectors.