We report the first dark matter search results from XENON1T, a~2000 kg dual-phase xenon time projection chamber in operation at the Laboratori Nazionali del Gran Sasso in Italy, the first ton-scale detector of this kind. The blinded search used 34.2 live days of data acquired between November 2016 and January 2017. Inside the (1042±12) kg fiducial mass and in the [5, 40] keVnr energy range of interest for WIMP dark matter searches, the electronic recoil background was (1.93±0.25)x10−4 events/(kg x day x keVee), the lowest ever achieved in a dark matter detector. A profile likelihood analysis shows that the data is consistent with the background-only hypothesis. We derive the most stringent exclusion limits on the spin-independent WIMP-nucleon interaction cross section for WIMP masses above 10 GeV/c2, with a minimum of 7.7 x10−47 cm2 for 35-GeV/c2 WIMPs at 90% confidence level.
In the full nominal 2 t y exposure, we expect to reach with XENON1T a sensitivity of 1.6 x10−47 cm2.
We will also present the future upgrade of the detector, XENONnT, with increased active mass and lower background, to foresee another order of magnitude improvement in sensitivity by 2024.