Dark Matter at Boulby Mine

Abstract

The Boulby Dark Matter Collaboration (BDMC) is running a WIMP Dark Matter research programme in the underground laboratory of Boulby Mine. The two axes of the programme are based on (1) liquid Xenon (LXe) as the WIMP target and (2) directional detection in low pressure gas detectors. ZEPLIN-1 is a 3.1kg of LXe scintillation detector with a background discrimination based on Pulse Shape Analysis. A new limit from a preliminary analysis is presented. Further generation setups with improved background discrimination tools (as the ionisation is also recorded) are in construction. ZEPLIN-2 and ZEPLIN-3, are predicted to be sensitive to rate of 0.1-0.01 events/kg/day within 2 years of data, with fiducial masses of 30kg and 6kg, respectively. These are important steps towards the design of a tonne-scale LXe Dark Matter detector array. The DRIFT programme relies on discrimination by tracking and directionnal detection. This enables the measurement of any sidereal modulation, as the earth's rotation changes the flux angle of Galactic WIMPs. A low pressure 1m$^3$ chamber (DRIFT-1) is currently taking data underground. A setup for a bigger volume with increased spatial resolution (enabling the pressure, and hence the target mass to be increase) is in the designing process.