Kinematic reconstruction of atmospheric neutrino events in a large water Cherenkov detector with proton identification

M. Fechner, K. Abe, Y. Hayato, T. Iida, M. Ikeda, J. Kameda, K. Kobayashi, Y. Koshio, M. Miura, S. Moriyama, M. Nakahata, S. Nakayama, Y. Obayashi, H. Ogawa, H. Sekiya, M. Shiozawa, Y. Suzuki, A. Takeda, Y. Takenaga, Y. TakeuchiK. Ueno, K. Ueshima, H. Watanabe, S. Yamada, S. Hazama, I. Higuchi, C. Ishihara, T. Kajita, K. Kaneyuki, G. Mitsuka, H. Nishino, K. Okumura, N. Tanimoto, M. R. Vagins, F. Dufour, E. Kearns, M. Litos, J. L. Raaf, J. L. Stone, L. R. Sulak, W. Wang, M. Goldhaber, S. Dazeley, R. Svoboda, K. Bayes, D. Casper, J. P. Cravens, W. R. Kropp, S. Mine, C. Regis, M. B. Smy, H. W. Sobel, K. S. Ganezer, J. Hill, W. E. Keig, J. S. Jang, J. Y. Kim, I. T. Lim, K. Scholberg, C. W. Walter, R. Wendell, S. Tasaka, J. G. Learned, S. Matsuno, Y. Watanabe, T. Hasegawa, T. Ishida, T. Ishii, T. Kobayashi, T. Nakadaira, K. Nakamura, K. Nishikawa, Y. Oyama, K. Sakashita, T. Sekiguchi, T. Tsukamoto, A. T. Suzuki, A. Minamino, T. Nakaya, M. Yokoyama, Y. Fukuda, Y. Itow, T. Tanaka, C. K. Jung, G. Lopez, C. McGrew, R. Terri, C. Yanagisawa, N. Tamura, Y. Idehara, M. Sakuda, Y. Kuno, M. Yoshida, S. B. Kim, B. S. Yang, T. Ishizuka, H. Okazawa, Y. Choi, H. K. Seo, Y. Furuse, K. Nishijima, Y. Yokosawa, M. Koshiba, Y. Totsuka, S. Chen, Y. Heng, Z. Yang, H. Zhang, D. Kielczewska, E. Thrane, R. J. Wilkes

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18 Citations (Scopus)

Abstract

We report the development of a proton identification method for the Super-Kamiokande (SK) detector. This new tool is applied to the search for events with a single proton track, a high purity neutral current sample of interest for sterile neutrino searches. After selection using a neural network, we observe 38 events in the combined SK-I and SK-II data corresponding to 2285.1 days of exposure, with an estimated signal-to-background ratio of 1.6 to 1. Proton identification was also applied to a direct search for charged-current quasielastic (CCQE) events, obtaining a high precision sample of fully kinematically reconstructed atmospheric neutrinos, which has not been previously reported in water Cherenkov detectors. The CCQE fraction of this sample is 55%, and its neutrino (as opposed to antineutrino) fraction is 91.7±3%. We selected 78μ-like and 47 e-like events in the SK-I and SK-II data set. With this data, a clear zenith angle distortion of the neutrino direction itself is reported in a sub-GeV sample of μ neutrinos where the lepton angular correlation to the incoming neutrino is weak. Our fit to νμ→ντ oscillations using the neutrino LE distribution of the CCQE sample alone yields a wide acceptance region compatible with our previous results and excludes the no-oscillation hypothesis at 3-sigma.

Original languageEnglish
Article number112010
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume79
Issue number11
DOIs
Publication statusPublished - Jun 22 2009

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)

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    Fechner, M., Abe, K., Hayato, Y., Iida, T., Ikeda, M., Kameda, J., Kobayashi, K., Koshio, Y., Miura, M., Moriyama, S., Nakahata, M., Nakayama, S., Obayashi, Y., Ogawa, H., Sekiya, H., Shiozawa, M., Suzuki, Y., Takeda, A., Takenaga, Y., ... Wilkes, R. J. (2009). Kinematic reconstruction of atmospheric neutrino events in a large water Cherenkov detector with proton identification. Physical Review D - Particles, Fields, Gravitation and Cosmology, 79(11), [112010]. https://doi.org/10.1103/PhysRevD.79.112010