Browsing by Author "Ishihara, K"

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    Measurement of neutrino oscillation with KamLAND: Evidence of spectral distortion
    (American Physical Society, 2005-03-01) Araki, T; Eguchi, K; Enomoto, S; Furuno, K; Ichimura, K; Ikeda, H; Inoue, K; Ishihara, K; Iwamoto, T; Kawashima, T; Kishimoto, Y; Koga, M; Koseki, Y; Maeda, T; Mitsui, T; Motoki, M; Nakajima, K; Ogawa, H; Owada, K; Ricol, JS; Shimizu, I; Shirai, J; Suekane, F; Suzuki, A; Tada, K; Tajima, O; Tamae, K; Tsuda, Y; Watanabe, H; Busenitz, J; Classen, T; Djurcic, Z; Keefer, G; McKinny, K; Mei, DM; Piepke, A; Yakushev, E; Berger, BE; Chan, YD; Decowski, MP; Dwyer, DA; Freedman, SJ; Fu, Y; Fujikawa, BK; Goldman, J; Gray, F; Heeger, KM; Lesko, KT; Luk, KB; Murayama, H; Poon, AWP; Steiner, HM; Winslow, LA; Horton-Smith, GA; Mauger, C; McKeown, RD; Vogel, P; Lane, CE; Miletic, T; Gorham, PW; Guillian, G; Learned, JG; Maricic, J; Matsuno, S; Pakvasa, S; Dazeley, S; Hatakeyama, S; Rojas, A; Svoboda, R; Dieterle, BD; Detwiler, J; Gratta, G; Ishii, K; Tolich, N; Uchida, Y; Batygov, M; Bugg, W; Efremenko, Y; Kamyshkov, Y; Kozlov, A; Nakamura, Y; Gould, CR; Karwowski, HJ; Markoff, DM; Messimore, JA; Nakamura, K; Rohm, RM; Tornow, W; Wendell, R; Young, AR; Chen, MJ; Wang, YF; Piquemal, F; Tohoku University; University of Alabama Tuscaloosa; University of California System; University of California Berkeley; United States Department of Energy (DOE); Lawrence Berkeley National Laboratory; California Institute of Technology; Drexel University; University of Hawaii System; University of Hawaii Manoa; Louisiana State University System; Louisiana State University; University of New Mexico; Stanford University; University of Tennessee System; University of Tennessee Knoxville; University of North Carolina; University of North Carolina Chapel Hill; Duke University; North Carolina State University; Chinese Academy of Sciences; Institute of High Energy Physics, CAS; UDICE-French Research Universities; Universite de Bordeaux; Centre National de la Recherche Scientifique (CNRS); CNRS - National Institute of Nuclear and Particle Physics (IN2P3)
    We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 (nu) over bar (e) candidate events with energies above 3.4 MeV compared to 365.2+/-23.7 events expected in the absence of neutrino oscillation. Accounting for 17.8+/-7.3 expected background events, the statistical significance for reactor (nu) over bar (e) disappearance is 99.998%. The observed energy spectrum disagrees with the expected spectral shape in the absence of neutrino oscillation at 99.6% significance and prefers the distortion expected from (nu) over bar (e) oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam(2)=7.9(-0.5)(+0.6)x10(-5) eV(2). A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam(2)=7.9(-0.5)(+0.6)x10(-5) eV(2) and tan(2)theta=0.40(-0.07)(+0.10), the most precise determination to date.