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T: Fachverband Teilchenphysik

T 98: Search for Dark Matter 4

T 98.3: Talk

Thursday, March 7, 2024, 16:30–16:45, Geb. 30.35: HSI

Results of the pure-water phase of the XENONnT neutron veto: The world's first water Cherenkov neutron veto — •Daniel Wenz for the XENON collaboration — Institut for Nuclear Physics University of Muenster

Liquid xenon time projection chambers (TPCs) play a key role in the direct search for dark matter such as Weakly Interacting Massive Particles (WIMPs). Neutrons emitted by traces of radioactive isotopes in the detector materials pose a great risk for the search of WIMPs as they can undergo single-scatter nuclear recoils and escape the TPC mimicking WIMP signals. To mitigate this background XENONnT was augmented with a new neutron veto (NV), designed as a Gadolinium water Cherenkov detector, which tags neutrons through their capture on gadolinium and hydrogen. In the first phase of XENONnT the neutron veto was operated using pure water only.

In this talk we will present results of the performance of the NV in this first phase, its calibration using coincident gammas and neutrons from an Americium-Beryllium source, and its impact on the first science search data of XENONnT.

The presented work is supported by the BMBF through the project numbers 05A20UM1 and 05A23PM1.

Keywords: Dark Matter; Water Cherenkov; Neutron Veto; Gadolinium