title: Time-Reversal Measurement of the p-Wave Cross Sections of the ^{7}Be(n,α)^{4}He Reaction for the Cosmological Li Problem.
abstract: The cross sections of the ^{7}Be(n,α)^{4}He reaction for p-wave neutrons were experimentally determined at E_{c.m.}=0.20-0.81  MeV slightly above the big bang nucleosynthesis (BBN) energy window for the first time on the basis of the detailed balance principle by measuring the time-reverse reaction. The obtained cross sections are much larger than the cross sections for s-wave neutrons inferred from the recent measurement at the n_TOF facility in CERN, but significantly smaller than the theoretical estimation widely used in the BBN calculations. The present results suggest the ^{7}Be(n,α)^{4}He reaction rate is not large enough to solve the cosmological lithium problem, and this conclusion agrees with the recent result from the direct measurement of the s-wave cross sections using a low-energy neutron beam and the evaluated nuclear data library ENDF/B-VII.1.
authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.lastname: Fujikawa
authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.lastname: Furuno
authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.lastname: Goto
authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Department of Physics, Tohoku University, Aoba, Sendai, Miyagi 980-8578, Japan.
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authors.lastname: Iwasa
authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.lastname: Kanada-En'yo
authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.|Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Koshikawa
authors.affiliation: RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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authors.lastname: Kubono
authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.initials: E
authors.lastname: Miyawaki
authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.lastname: Mizuno
authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.lastname: Mizutani
authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.|Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.|Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.lastname: Nanamura
authors.affiliation: RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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authors.lastname: Nishimura
authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
authors.forename: S
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authors.lastname: Okamoto
authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.lastname: Sakaguchi
authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.lastname: Sakata
authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.lastname: Sakaue
authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.lastname: Shikata
authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
authors.forename: D
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authors.lastname: Takechi
authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.|Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Department of Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.|Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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authors.affiliation: Faculty of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
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