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arXiv · 2409.10611

Neutron Tagging Can Greatly Reduce Spallation Backgrounds in Super-Kamiokande

Obada Nairat·John F. Beacom·Shirley Weishi Li
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Abstract

Super-Kamiokande's spallation backgrounds - the delayed beta decays of nuclides following cosmic-ray muons - are nearly all produced by the small fraction of muons with hadronic showers. We show that these hadronic showers also produce neutrons; their captures can be detected with high efficiency due to the recent addition of dissolved gadolinium to Super-Kamiokande. We show that new cuts based on the neutron tagging of showers could reduce spallation backgrounds by a factor of at least four beyond present cuts. With further work, this could lead to a near-elimination of detector backgrounds above about 6 MeV, which would significantly improve the sensitivity of Super-Kamiokande. These findings heighten the importance of adding gadolinium to Hyper-Kamiokande, which is at a shallower depth. Further, a similar approach could be used in other detectors, for example, the JUNO liquid-scintillator detector, which is also at a shallower depth.

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Obada Nairat, John F. Beacom, Shirley Weishi Li. 2024-09-16. Neutron Tagging Can Greatly Reduce Spallation Backgrounds in Super-Kamiokande. https://doi.org/10.1103/physrevd.111.023014

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