The LUX-ZEPLIN dark matter search project is our main research activity. We are part of the Oxford sub-department of Particle Physics. Our laboratories can be found on level 5 of the Denys Wilkinson Building, where we developed instrumentation for LZ, work on simulations and data analysis tools, and engage in R&D for a next-generation liquid xenon dark matter detector.
LZ consists of a 7-ton liquid xenon target, of which 5.6 t are the fiducial mass. LZ has an active veto system for suppressing background events. All this is inside a water tank inside the Sanford Underground Research Facility.
The direct detection of dark matter is one of the biggest contemporary challenges in experimental physics. Evidence that the matter in the Universe is dominated by an invisible component has been accumulating for many years, initially from measurements of the rotation curves of spiral galaxies, and the speeds of individual galaxies within clusters; and more recently from precision measurements of the cosmic microwave background. Astrophysical evidence, together with precision cosmology results suggest that in a ΛCDM model there are contributions from dark energy (68%), baryonic matter (5%) and dark matter (27%).
Particle physics theories provide a possible explanation for dark matter in the form of WIMPs - weakly interacting massive particles. WIMP candidates include the neutralino, a possible lightest supersymmetric particle; and Kaluza Klein particles associated with compactified extra dimensions. Particle accelerator experiments such as those at the LHC aim to produce these particles; however the only way to conclusively show that they account for dark matter in the galaxy, would be by the confirmed discovery of direct WIMP interactions. This is the aim of direct dark matter search experiments, such as LUX-ZEPLIN.
The scattering cross section of a supersymmetric WIMP off atomic nuclei is expected to be very low, corresponding to only a few events a year in a one tonne detector. Detecting such rare events requires very sensitive detectors with excellent background discrimination.