Neutron-Multiplicity Measurement in Muon Capture on Oxygen Nuclei in the Gadolinium-Loaded Super-Kamiokande Detector
Open Access
- 31 March 2026
- journal article
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 136 (13) , 131801
Abstract
In recent neutrino detectors, neutrons produced in neutrino reactions play an important role. Muon capture on oxygen nuclei is one of the processes that produce neutrons in water Cherenkov detectors. We measured neutron multiplicity in the process using cosmic ray muons that stop in the gadolinium-loaded Super-Kamiokande detector. For this measurement, neutron detection efficiency is obtained with the muon capture events followed by gamma rays to be 50.2 − 2.1 + 2.0 % . By fitting the observed multiplicity considering the detection efficiency, we measure neutron multiplicity in muon capture as P ( 0 ) = 24 ± 3 % , P ( 1 ) = 7 0 − 2 + 3 % , P ( 2 ) = 6.1 ± 0.5 % , P ( 3 ) = 0.38 ± 0.09 % . This is the first measurement of the multiplicity of neutrons associated with muon capture on oxygen without neutron energy threshold.Keywords
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Funding Information
- Ministry of Education, Culture, Sports, Science and Technology
- U.S. Department of Energy
- National Science Foundation
- National Research Foundation of Korea (NRF-2009-0083526)
- National Research Foundation of Korea (NRF-2022R1A5A1030700)
- National Research Foundation of Korea (NRF-2022R1A3B1078756)
- Institute for Basic Science (IBS-R016-Y2)
- Ministry of Education, Science and Technology (2018R1D1A1B07049158)
- Ministry of Education, Science and Technology (2021R1I1A1A01042256)
- Ministry of Education, Science and Technology (2021R1I1A1A01059559)
- Ministry of Education, Science and Technology (RS-2024-00442775)
- Japan Society for the Promotion of Science
- National Natural Science Foundation of China (12375100)
- Ministerio de Ciencia e Innovación (PID2021-124050NB-C31)
- Natural Sciences and Engineering Research Council of Canada
- Compute Canada
- Narodowe Centrum Nauki (UMO-2018/30/E/ST2/00441)
- Narodowe Centrum Nauki (UMO-2022/46/E/ST2/00336)
- Ministerstwo Edukacji i Nauki (2023/WK/04)
- Science and Technology Facilities Council
- Horizon 2020 Framework Programme
- HORIZON EUROPE Marie Sklodowska-Curie Actions (754496)
- HORIZON EUROPE Marie Sklodowska-Curie Actions (822070)
- HORIZON EUROPE Marie Sklodowska-Curie Actions (872549)
- NextGenerationEU (CA3/RSUE2021-00559)
- Instituto Nazionale di Fisica Nucleare
- PRTR
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