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arXiv · 2505.22547

First measurement of neutron capture multiplicity in neutrino-oxygen neutral-current quasi-elastic-like interactions using an accelerator neutrino beam

T2K Collaboration·K. Abe·S. Abe·R. Akutsu·H. Alarakia-Charles·Y. I. Alj Hakim·S. Alonso Monsalve·L. Anthony·M. Antonova·S. Aoki·K. A. Apte·T. Arai·T. Arihara·S. Arimoto·Y. Asada·Y. Ashida·N. Babu·G. Barr·D. Barrow·P. Bates·M. Batkiewicz-Kwasniak·V. Berardi·L. Berns·S. Bordoni·S. B. Boyd·C. Bronner·A. Bubak·M. Buizza Avanzini·J. A. Caballero·N. F. Calabria·S. Cao·D. Carabadjac·S. L. Cartwright·M. P. Casado·M. G. Catanesi·J. Chakrani·A. Chalumeau·P. S. Chong·A. Chvirova·G. Collazuol·F. Cormier·A. Cudd·D. D'ago·C. Dalmazzone·T. Daret·P. Dasgupta·C. Davis·Yu. I. Davydov·A. De Roeck·G. De Rosa·T. Dealtry·C. Densham·A. Dergacheva·R. Dharmapal Banerjee·F. Di Lodovico·G. Diaz Lopez·S. Dolan·D. Douqa·T. A. Doyle·O. Drapier·K. E. Duffy·J. Dumarchez·K. Dygnarowicz·A. Eguchi·J. Elias·S. Emery-Schrenk·G. Erofeev·A. Ershova·G. Eurin·D. Fedorova·S. Fedotov·M. Feltre·L. Feng·D. Ferlewicz·A. J. Finch·G. Fiorillo·M. D. Fitton·J. M. Franco Patiño·M. Friend·Y. Fujii·Y. Fukuda·Y. Furui·L. Giannessi·C. Giganti·V. Glagolev·M. Gonin·J. González Rosa·K. Gorshanov·M. Guigue·D. R. Hadley·J. T. Haigh·S. Han·D. A. Harris·T. Hasegawa·S. Hassani·Y. Hayato·I. Heitkamp·D. Henaff·Y. Hino·M. Hogan
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Abstract

We report the first measurement of neutron capture multiplicity in neutrino-oxygen neutral-current quasi-elastic-like interactions at the gadolinium-loaded Super-Kamiokande detector using the T2K neutrino beam, which has a peak energy of about 0.6 GeV. A total of 30 neutral-current quasi-elastic-like event candidates were selected from T2K data corresponding to an exposure of $1.76\times10^{20}$ protons on target. The $\gamma$ ray signals resulting from neutron captures were identified using a neural network. The flux-averaged mean neutron capture multiplicity was measured to be $1.37\pm0.33\text{ (stat.)}$$^{+0.17}_{-0.27}\text{ (syst.)}$, which is compatible within $2.3\,\sigma$ than predictions obtained using our nominal simulation. We discuss potential sources of systematic uncertainty in the prediction and demonstrate that a significant portion of this discrepancy arises from the modeling of hadron-nucleus interactions in the detector medium.

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T2K Collaboration, K. Abe, S. Abe, R. Akutsu, H. Alarakia-Charles, Y. I. Alj Hakim, S. Alonso Monsalve, L. Anthony, M. Antonova, S. Aoki, K. A. Apte, T. Arai, T. Arihara, S. Arimoto, Y. Asada, Y. Ashida, N. Babu, G. Barr, D. Barrow, P. Bates, M. Batkiewicz-Kwasniak, V. Berardi, L. Berns, S. Bordoni, S. B. Boyd, C. Bronner, A. Bubak, M. Buizza Avanzini, J. A. Caballero, N. F. Calabria, S. Cao, D. Carabadjac, S. L. Cartwright, M. P. Casado, M. G. Catanesi, J. Chakrani, A. Chalumeau, P. S. Chong, A. Chvirova, G. Collazuol, F. Cormier, A. Cudd, D. D'ago, C. Dalmazzone, T. Daret, P. Dasgupta, C. Davis, Yu. I. Davydov, A. De Roeck, G. De Rosa, T. Dealtry, C. Densham, A. Dergacheva, R. Dharmapal Banerjee, F. Di Lodovico, G. Diaz Lopez, S. Dolan, D. Douqa, T. A. Doyle, O. Drapier, K. E. Duffy, J. Dumarchez, K. Dygnarowicz, A. Eguchi, J. Elias, S. Emery-Schrenk, G. Erofeev, A. Ershova, G. Eurin, D. Fedorova, S. Fedotov, M. Feltre, L. Feng, D. Ferlewicz, A. J. Finch, G. Fiorillo, M. D. Fitton, J. M. Franco Patiño, M. Friend, Y. Fujii, Y. Fukuda, Y. Furui, L. Giannessi, C. Giganti, V. Glagolev, M. Gonin, J. González Rosa, K. Gorshanov, M. Guigue, D. R. Hadley, J. T. Haigh, S. Han, D. A. Harris, T. Hasegawa, S. Hassani, Y. Hayato, I. Heitkamp, D. Henaff, Y. Hino, M. Hogan. 2025-05-28. First measurement of neutron capture multiplicity in neutrino-oxygen neutral-current quasi-elastic-like interactions using an accelerator neutrino beam. https://arxiv.org/abs/2505.22547

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