Improving the optical readout instrumentation and supernova-readiness of XLZD, the next-generation dark matter experiment

ongoing

"Understanding the nature of dark matter (DM) is a primary question in modern physics. Dual-phase liquid xenon (LXe) time projection chambers (TPCs) have led the search for particle DM, particularly for DM candidates above ~5 GeV. Building on the success of current experiments like XENONnT and LZ, the XLZD consortium aims to design, construct, and operate a 60-80 t LXe-TPC to probe WIMP-nucleon cross-sections down to the neutrino fog limit. XLZD will also search for low-energy solar neutrinos, neutrinoless double beta decay, solar axions, and supernova neutrinos, making it a genuine ""rare event observatory."" In this context, I propose to enhance the optical readout system for the LXe skin detector using silicon photomultipliers (SiPMs) and to study the sensitivity of the TPC to supernova (SN) neutrinos. The first part of the project is designing and characterizing VUV SiPMs and a minimal-radioactivity readout system for the LXe skin region. Achieving a 100 keV threshold will improve gamma-ray tagging from the active target, reducing electronic recoil background and, to a lesser extent, the nuclear recoil background. A prototype will be developed and tested at Imperial College London (ICL) and later at the University of Zurich (UZH), including in LXe. The second part focuses on enhancing the SN detection capabilities of LXe detectors, including contributions to an online SN monitor for the LZ experiment and its integration with the Supernova Early Warning System (SNEWS). The project will assess XLZD's sensitivity to SN neutrinos, evaluating its potential impact on neutrino property measurements and SN model discrimination, and contribute to the design of a parallel DAQ system for near-continuous SN monitoring. The proposed research will significantly advance the design and physics reach of next-generation xenon-based dark matter detectors, while fostering collaboration between ICL and UZH, uniting expertise from previous LZ and XENONnT projects for the XLZD experiment"