ZEPLIN-I: a single phase liquid Xe detector for dark matter search

The UK Dark Matter Collaboration is developing a series of liquid Xe detectors to search for the hypothetical weakly interacting massive particles (WIMPs) which may comprise a significant component of the Galactic dark matter. These detectors will be operated at a depth of 1100 m in the Boulby salt mine. The first of these detectors, ZEPLIN-I is a 1.7 litre single phase liquid Xe scintillation detector which employs pulse shape discrimination analysis to distinguish nuclear recoils due to WIMPs from electron recoils from background gamma interactions. The current status of ZEPLIN-I is presented in this paper. The detector design will be described and results discussed of tests on the detector performance using various types of radioactive sources in the 10 keV-1 MeV energy range. The light yield at the level of 1 photoelectron per 1 keV of deposited energy has been achieved. Clear discrimination between gamma initiated electron recoils and neutron initiated nuclear recoils has been observed. The discrimination potential below 100 keV, and subsequent expected sensitivity to dark matter particles, will be outlined.