Neutron Tagging Can Greatly Reduce Spallation Backgrounds in Super-Kamiokande

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.

Main text is 14 pages. Minor changes to match the published version

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Cited by in corpus (3)

• A $\nu$ look at the Sun: Probing the conditions of the solar core using ${}^8$B neutrinos
• Towards First Detection of the Solar MSW Transition With JUNO
• New Spallation Background Rejection Techniques to Greatly Improve the Solar Neutrino Sensitivity of JUNO