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Phys. Rev. C 71, 055803 (2005) [8 pages]

7Li(n,γ)8Li reaction and the S17 factor at Ec.m.>500 keV

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Y. Nagai1, M. Igashira2, T. Takaoka3,*, T. Kikuchi3,†, T. Shima1, A. Tomyo1,‡, A. Mengoni4,5,6, and T. Otsuka4,6
1Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 667-0047, Japan
2Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8550, Japan
3Department of Applied Physics, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8551, Japan
4The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-01, Japan
5National Institute for New Technologies, Energy and Environment (ENEA), v. Don Fiammellei 2, I- 40128 Bologna, Italy
6Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan

Received 19 December 2004; published 19 May 2005

The partial cross sections from the neutron capture state to the ground and first excited states in 8Li have been separately determined for the first time at stellar neutron energy. The direct and weak cascade γ rays from the capture and first excited states to the ground state were measured by means of anti-Compton NaI(Tl) and anti-Compton HPGe spectrometers, respectively. The γ-ray branching ratio and the cross sections thus determined agree with that for thermal neutrons assuming a 1/v neutron velocity dependence. By comparing the cross sections with calculations based on the nonresonant direct capture mechanism it is shown that the cross sections are sensitive to the interaction potential of the incident neutron with the 7Li target nucleus. This analysis confirms the possibility of deriving the parameters necessary for the calculation of the astrophysical S factor S17(E) for the 7Be(p,γ)8B reaction in the upper energy range above 500 keV.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevC.71.055803
DOI:
10.1103/PhysRevC.71.055803
PACS:
25.40.Lw, 21.10.Jx, 26.65.+t, 29.30.Kv

*Present address: Nikon Corporation, 201-9, Miizugahara, Kumagaya Saitama, 360-8559, Japan.

†Present address: Hitachi, Ltd. 1-1, Saiwai-cho 3-chome, Hitachi-shi Ibaraki-ken, 317-8511, Japan.

‡Present address: Nissin Electric Co., Ltd., 47 Umezu-Takase-cho, Ukyo-ku, Kyoto 615-8686, Japan.

 
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