Limits on light WIMPs with a 1 kg-scale germanium detector at 160 eVee physics threshold at the China Jinping Underground Laboratory

We report the first dark matter search results from XENON1T, a \(\sim\)2000-kg-target-mass dual-phase (liquid-gas) xenon time projection chamber in operation at the Laboratori Nazionali del Gran Sasso in Italy and 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\(\pm\)12) kg fiducial mass and in the [5, 40] \(\mathrm{keV}_{\mathrm{nr}}\) energy range of interest for WIMP dark matter searches, the electronic recoil background was \((1.93 \pm 0.25) \times 10^{-4}\) events/(kg \(\times\) day \(\times \mathrm{keV}_{\mathrm{ee}}\)), 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/c\({}^2\), with a minimum of 7.7 \(\times 10^{-47}\) cm\({}^2\) for 35-GeV/c\({}^2\) WIMPs at 90% confidence level.

We report a new search of weakly interacting massive particles (WIMPs) using the combined low background data sets in 2016 and 2017 from the PandaX-II experiment in China. The latest data set contains a new exposure of 77.1 live day, with the background reduced to a level of 0.8\(\times10^{-3}\) evt/kg/day, improved by a factor of 2.5 in comparison to the previous run in 2016. No excess events were found above the expected background. With a total exposure of 5.4\(\times10^4\) kg day, the most stringent upper limit on spin-independent WIMP-nucleon cross section was set for a WIMP with mass larger than 100 GeV/c\(^2\), with the lowest exclusion at 8.6\(\times10^{-47}\) cm\(^2\) at 40 GeV/c\(^2\).