1. Time-Reversal Measurement of the p-Wave Cross Sections of the ^{7}Be(n,α)^{4}He Reaction for the Cosmological Li Problem
- Author
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Kawabata, T., Fujikawa, Y., Furuno, T., Goto, T., Hashimoto, T., Ichikawa, M., Itoh, M., Iwasa, N., Kanada-En’yo, Y., Koshikawa, A., Kubono, S., Miyawaki, E., Mizuno, M., Mizutani, K., Morimoto, T., Murata, M., Nanamura, T., Nishimura, S., Okamoto, S., Sakaguchi, Y., Sakata, I., Sakaue, A., Sawada, R., Shikata, Y., Takahashi, Y., Takechi, D., Takeda, T., Takimoto, C., Tsumura, M., Watanabe, K., and Yoshida, S.
- 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.
- Published
- 2016