Boulby Development Call: XLZD Infrastructure

Discovering the nature of particle dark matter (DM) is a key priority in Physics - and for STFC. Direct detection of electroweak-scale DM in our galaxy is the primary goal of the XLZD consortium, formed by the coming together of the foremost collaborations in the field: XENON-nT, LUX-ZEPLIN (LZ) and DARWIN. XLZD is proposing a large underground experiment based on the leading liquid xenon (LXe) technology: the definitive search for WIMP DM, able to rule out or discover in the accessible parameter space remaining above the irreducible neutrino background. The scientific potential of such a "rare event observatory" is detailed in a comprehensive white paper signed by 600 authors worldwide. LZ and Xenon-nT are the leading experiments in the field at present. Discovery of DM at XLZD would have profound implications for our understanding of the universe, its birth and its structure.

STFC is currently considering a proposal to host the XLZD experiment in a state-of-the-art new facility at the Boulby Underground Laboratory in North Yorkshire (XLZD@Boulby). A liquid xenon rare event observatory might well be the largest project hosted at Boulby, supported by the largest international collaboration visiting the facility, and hence it would drive the facility design to a significant degree. This project sets up the academic and technical interactions related to the configuration of underground and surface spaces and facilities, and to the transportation and underground manufacture of large items. Additionally, this project develops the more challenging hazard analyses that impact facility design, and it explores management and governance interfaces between the facility and the experiment.