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T: Fachverband Teilchenphysik
T 45: Searches for Dark Matter I
T 45.9: Talk
Tuesday, March 16, 2021, 18:00–18:15, Tt
The ultra-low energy calibration based on a diluted 37Ar source at the XENON experiment — •Matteo Alfonsi for the XENON collaboration — Institut für Physik & Exzellenzcluster PRISMA+, JGU Mainz, 55099 Mainz, Germany
The XENONnT experiment for direct Dark Matter detection is currently under commissioning. It is the upgrade of the XENON1T experiment and more than 20 times better sensitivity is expected from the three times larger target mass and the six times smaller background. The calibration of the detector response for ton-scale xenon Time Projection Chambers relies mostly on the dilution of gaseous radioisotopes such as 83mKr and 220Rn into the liquid xenon. A novel calibration possibility based on the injection of the gaseous 37Ar isotope and the subsequent active removal by cryogenic distillation has been demonstrated at the end of the XENON1T operation. This radioactive source has been produced with high purity by neutron capture in the TRIGA research reactor in Mainz, and its decay by electron capture (causing an X-ray and Auger electrons cascade) provided two unprecedented ultra-low energy calibration lines at 2.8 keV and 270 eV, which were crucial to validate the detector response model for several XENON1T results. Due to the relatively long decay time of the 37Ar, 35.0 days, the proof of the cryogenic distillation active removal method has been the key for the consideration of this technique during the XENONnT operation.
This talk reports the results of the XENON1T calibration test and describe the new 37Ar injection system installed in XENONnT.