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Measurement of neutrino oscillation with KamLAND: Evidence of spectral distortion

Araki, T. and Horton-Smith, G. A. and Mauger, C. and McKeown, R. D. and Vogel, P. (2005) Measurement of neutrino oscillation with KamLAND: Evidence of spectral distortion. Physical Review Letters, 94 (8). Art. No. 081801. ISSN 0031-9007. doi:10.1103/PhysRevLett.94.081801.

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We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 v_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 v_e 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 v_e oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Δm^2=7.9_(-0.5)^(+0.6)x10^(-5) eV^2. A global analysis of data from KamLAND and solar-neutrino experiments yields Δm^2=7.9_(-0.5)^(+0.6)x10^(-5) eV^2 and tan^2θ=0.40_(-0.07)^(+0.10), the most precise determination to date.

Item Type:Article
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Vogel, P.0000-0003-0587-5466
Additional Information:© 2005 The American Physical Society. Received 15 June 2004; published 1 March 2005. The KamLAND experiment is supported by the COE program under grant no. 09CE2003 of the Japanese Ministry of Education, Culture, Sports, Science, and Technology, and under the United States Department of Energy grant no. DEFG03-00ER41138. The reactor data are provided by courtesy of the following electric associations in Japan: Hokkaido, Tohoku, Tokyo, Hokuriku, Chubu, Kansai, Chugoku, Shikoku, and Kyushu Electric Power Companies, Japan Atomic Power Co., and Japan Nuclear Cycle Development Institute. The Kamioka Mining and Smelting Company has provided service for activities in the mine.
Funding AgencyGrant Number
Japanese Ministry of Education, Culture, Sports, Science and Technology09CE2003
Department of Energy (DOE)DEFG03-00ER41138
Issue or Number:8
Classification Code:PACS: 14.60.Pq, 26.65.+t, 28.50.Hw
Record Number:CaltechAUTHORS:20110513-104709373
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Official Citation:Measurement of Neutrino Oscillation with KamLAND: Evidence of Spectral Distortion T. Araki et al. (KamLAND Collaboration) Published 1 March 2005 (5 pages) 081801
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23661
Deposited By: Ruth Sustaita
Deposited On:17 May 2011 18:26
Last Modified:09 Nov 2021 16:16

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