Xenon Futures: R&D to construct the ultimate Dark Matter detectorThe LZ experiment will explore completely uncharted parameter space in the search for first evidence of galactic dark matter in the form of Weakly Interacting Massive Particles (WIMPs). There is international consensus that beyond LZ at least one Xe-based 'Generation-3' or 'G3' experiment will be constructed. In fact, the world-leading LZ and XENON/DARWIN collaborations have agreed to do just that - joining forces to construct this mammoth experiment.
G3 guarantees a fundamental change in particle physics; delivering either a high statistics confirmation of any hint of WIMP signal in LZ or XENONnT, a first WIMP discovery, or ruling out the existence of WIMPs across the remaining accessible electroweak parameter space, down to an irreducible background that comes from neutrinos from the sun, the atmosphere and supernovae, generating signals that look much like WIMPs. Achieving this unprecedented sensitivity will be non mean feat: G3 will need to be 10 times more sensitive than LZ, whose science reach is shown below along with indicative G3 sensitivity.
R&D towards realisation of a G3 instrument is beginning around the world and is a strategic priority in the UK, supported through STFC through the ‘Xenon Futures’ project. Xenon Futures will enable UK expertise in the world leading xenon TPC technology to target specific challenges related to scaling up by another order of magnitude. Whether discovery of WIMPs or the significance of null results on current ‘beyond the Standard Model’ (BSM) theories, world-class science is assured, and this extends well beyond WIMPs. G3’s reach to alternative non-WIMP dark matter and BSM physics that LZ and XENONnT will first explore warrants specific consideration in designs for the experiment. With a 50-70 tonne target and backgrounds 2 orders of magnitude lower than LZ, G3’s potential for new physics will be extraordinary. Moving beyond WIMPs as the primary science driver and optimising G3 as a rare-event observatory for the broadest range of new physics and BSM searches with discovery potential requires the focussed effort, experience and expertise with Xe TPC design and construction, sensitivity studies, backgrounds, and linkages with the international G3 R&D.
UCL are leading some of the low-background developments necessary for G3, from advanced radio purity techniques to ensure radiopure construction, to Monte Carlo simulations and modelling backgrounds to optimise sensitivity to new physics.