Measurement of the cosmogenic neutron yield in Super-Kamiokande with gadolinium loaded water

Abstract

Cosmic-ray muons that enter the Super-Kamiokande detector cause hadronic showers due to spallation in water, producing neutrons and radioactive isotopes. These are a major background source for studies of MeV-scale neutrinos and searches for rare events. In 2020, gadolinium was introduced into the ultra-pure water in the Super-Kamiokande detector to improve the detection efficiency of neutrons. In this study, the cosmogenic neutron yield was measured using data acquired during the period after the gadolinium loading. The yield was found to be (2.76±0.02(stat)±0.19(syst))×10-4 μ-1 g-1 cm2 at an average muon energy 259 GeV at the Super-Kamiokande detector. © 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the https://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.