04.08.2023First dark matter search results from XENONnT

The results were published in Physical Review Letters this week. No significant excess of nuclear recoil events with energies between 3.3 and 60.5 keV was found in a blind analysis. With this, the collaboration placed a best upper limit of 2.58 × 10⁻⁴⁷ cm² on the spin-independent WIMP-nucleon cross-section for a 28 GeV / c² WIMP at 90 % confidence level. The data analysis used 95.1 days of data acquired between July and November 2021 in a sensitive (4.18 ± 0.13) tonne inner volume of the XENONnT dual-phase time projection chamber that holds a total of 5.9 tonnes of liquid xenon. Together with the LZ and PandaX-4t experiments, XENONnT places the most stringent constraints on WIMP interactions and significantly improves on the previously leading XENON1T results. This was enabled by reducing the intrinsic ⁸⁵Kr and ²²²Rn concentrations in the liquid target to unprecedented levels, giving an electronic recoil background rate of (15.8 ± 1.3) events per tonne, year and keV in the region of interest. Since the conclusion of its first science run, XENONnT has continued its multi-year measurement campaign in order to improve constraints on and ultimately detect WIMP dark matter interactions.