The XENON1T Dark Matter Search Experiment

Abstract: The worldwide race towards direct dark matter detection in the form of Weakly Interacting Massive Particles (WIMPs) has been dramatically accelerated by the remarkable progress and evolution of liquid xenon time projection chambers (LXeTPCs). With a realistic discovery potential, XENON100 has already reached a sensitivity of $7\times10^{-45}\,\n{cm}^2$, and continues to accrue data at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy towards its ultimate sensitivity reach at the $\sigma_{\n{SI}}\sim 2\times10^{-45}\,\n{cm}^2$ level for the spin-independent WIMP-nucleon cross-section. To fully explore the favoured parameter space for WIMP dark matter in search of a first robust and statistically significant discovery, or to confirm any hint of a signal from \Xehund, the next phase of the XENON program will be a detector at the ton scale - XENON1T. The XENON1T detector, based on 2.2 ton of LXe viewed by low radioactivity photomultiplier tubes and housed in a water Cherenkov muon veto at LNGS, is presented. With an experimental aim of probing WIMP interaction cross-sections above of order $\sigma_{\n{SI}}\sim 2\times10^{-47}\,\n{cm}^2$ within 2 years of operation, XENON1T will provide the sensitivity to probe a particularly favourable region of electroweak physics on a timescale compatible with complementary ground and satellite based indirect searches and with accelerator dark matter searches at the LHC. Indeed, for a $\sigma_{\n{SI}} \sim 10^{-45}\,\n{cm}^2$ and $100 \,\n{GeV/c^2}$ WIMP mass, XENON1T could detect of order 100 events in this exposure, providing statistics for placing significant constraints on the WIMP mass.