Performances and first results of the Neutron Veto of XENONnT.

Mancuso A.
  Giovedì 15/09   15:00 - 18:30   Aula T - Caterina Scarpellini   III - Astrofisica   Presentazione
The Neutron Veto of the XENONnT experiment is a Gd-loaded water Cherenkov detector designed to detect the radiogenic neutrons coming from the detector materials, in order to reduce one of the main nuclear recoil background components in the XENONnT time projection chamber. The Neutron Veto (NV) is instrumented with 120 ($8^{\prime\prime}$ Hamamatsu R5912) photomultiplier tubes, featuring high-$QE$ and low radioactivity, installed in a high light collection volume delimited by ePTFE reflector panels all around the cryostat. The XENONnT experiment is currently taking Science Data, with the NV operating in demi-water; in this contribution, I will overview the NV working principle and its initial performances in terms of PMT main parameters and in terms of neutron tagging efficiency, as resulting from the calibration and first months of data-taking.