The UKDMC dark matter xenon programme: New WIMP limits and progress towards 1-tonne

We outline recent progress from the liquid xenon WIMP search programme at Boulby. This comprises a staged series of three experiments, ZEPLIN I, II and III, aimed simultaneously to improve sensitivity towards 10−8 pb spin independent cross-section and to provide a test-bed for the design of a full-scale 1 tonne detector capable of reaching below 10−9 pb. First preliminary results from ZEPLIN I are presented, yielding a limit approaching 4 × 10−6 pb, with final sensitivity now projected to reach below 10−6 pb with 8 months more running. We describe progress also on the development and construction of ZEPLIN II and III, both of which use simultaneous collection of primary and secondary elecroluminescence signals, plus preliminary design work on the ZEPLIN-MAX 1 tonne experiment.