Results from the First Science Run of the ZEPLIN-III Dark Matter Search Experiment

TL;DR

The ZEPLIN-III experiment used a 12kg xenon detector to search for dark matter WIMPs, setting new limits on their interaction and demonstrating improved discrimination capabilities over previous xenon detectors.

Contribution

First results from ZEPLIN-III using a two-phase xenon detector, providing new constraints on WIMP interactions and showcasing enhanced background discrimination.

Findings

Excluded WIMP-nucleon cross-section above 8.1x10^(-8) pb at 55 GeV/c^2

Demonstrated improved electron/nuclear recoil discrimination at low energies

Analyzed 847 kg-days of data from 2008

Abstract

The ZEPLIN-III experiment in the Palmer Underground Laboratory at Boulby uses a 12kg two-phase xenon time projection chamber to search for the weakly interacting massive particles (WIMPs) that may account for the dark matter of our Galaxy. The detector measures both scintillation and ionisation produced by radiation interacting in the liquid to differentiate between the nuclear recoils expected from WIMPs and the electron recoil background signals down to ~10keV nuclear recoil energy. An analysis of 847kg.days of data acquired between February 27th 2008 and May 20th 2008 has excluded a WIMP-nucleon elastic scattering spin-independent cross-section above 8.1x10(-8)pb at 55GeV/c2 with a 90% confidence limit. It has also demonstrated that the two-phase xenon technique is capable of better discrimination between electron and nuclear recoils at low-energy than previously achieved by other xenon-based experiments.