Reactor on-off antineutrino measurement with KamLAND

A. Gando, Y. Gando, H. Hanakago, H. Ikeda, K. Inoue, K. Ishidoshiro, H. Ishikawa, M. Koga, R. Matsuda, S. Matsuda, T. Mitsui, D. Motoki, K. Nakamura, A. Obata, A. Oki, Y. Oki, M. Otani, I. Shimizu, J. Shirai, A. SuzukiY. Takemoto, K. Tamae, K. Ueshima, H. Watanabe, B. D. Xu, S. Yamada, Y. Yamauchi, H. Yoshida, A. Kozlov, S. Yoshida, A. Piepke, T. I. Banks, B. K. Fujikawa, K. Han, T. O'Donnell, B. E. Berger, J. G. Learned, S. Matsuno, M. Sakai, Y. Efremenko, H. J. Karwowski, D. M. Markoff, W. Tornow, J. A. Detwiler, S. Enomoto, M. P. Decowski

Research output: Contribution to journalArticlepeer-review

273 Citations (Scopus)


The recent long-term shutdown of Japanese nuclear reactors has resulted in a significantly reduced reactor ν̄e flux at KamLAND. This running condition provides a unique opportunity to confirm and constrain backgrounds for the reactor ν̄e oscillation analysis. The data set also has improved sensitivity for other ν̄e signals, in particular ν̄e's produced in β-decays from U238 and Th232 within the Earth's interior, whose energy spectrum overlaps with that of reactor ν̄e's. Including constraints on θ13 from accelerator and short-baseline reactor neutrino experiments, a combined three-flavor analysis of solar and KamLAND data gives fit values for the oscillation parameters of tan12=0.436-0.025+0.029, Δm212=7.53-0.18+0.18×10-5 eV2, and sin13=0.023-0.002+0.002. Assuming a chondritic Th/U mass ratio, we obtain 116-27+28 ν̄e events from U238 and Th232, corresponding to a geo ν̄e flux of 3.4-0.8+0.8×106 cm-2 s-1 at the KamLAND location. We evaluate various bulk silicate Earth composition models using the observed geo ν̄e rate.

Original languageEnglish
Article number033001
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number3
Publication statusPublished - 2013 Aug 2


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