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Phys. Rev. C 67, 015806 (2003) [7 pages]

Astrophysical reaction rate for the 8Li(n,γ)9Li reaction

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Hiroshi Kobayashi1 *, Kazuo Ieki1, Ákos Horváth2, Aaron Galonsky3, Nelson Carlin4, Ferenc Deák2, Tomoko Gomi1, Valdir Guimaraes5 †, Yoshihide Higurashi1 ‡, Yoshiyuki Iwata1 §, Ádám Kiss2, James J. Kolata5, Thomas Rauscher6, Hugo Schelin7, Zoltan Seres8, and Robert Warner9
1Department of Physics, Rikkyo University, 3 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan
2Department of Atomic Physics, Eötvös Loránd University, Pázmány P. sétány 1/A, H-1117 Budapest, Hungary
3National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1321
4Instituto de Física, Universidade de São Paulo, Departamento de Física Nuclear, Laboratório Palletron, Caixa Postal 66318, 05315-970, São Paulo, Brazil
5Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556-5670
6Department of Physics and Astronomy, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
7CEFET, Av. Sete de Setembro 3165 80230-901, Curitiba, Pr, Brazil
8KFKI Research Institute for Particle and Nuclear Physics, Konkoly-Thege út 29-33, P.O. Box 49, H-1525 Budapest 114, Hungary
9Department of Physics, Oberlin College, Oberlin, Ohio 44074

Received 29 October 2002; published 23 January 2003

An attempt was made to measure the excitation function of the cross section for the 8Li(n,γ)9Li reaction by performing the inverse reaction 9Li(γ,n)8Li, with the equivalent photons in the electric field of nuclei in a Pb target providing the γ rays for the reaction. The energy spectrum of lithium nuclei in coincidence with neutrons had no discernible peak where any beam-velocity 8Li’s would be located. Statistically, a Gaussian-shaped 8Li peak could have been present with 30±29 counts, which we interpreted as consistent with zero, with a two-standard-deviation upper limit of 87 counts. Using the fact that neutron capture on 8Li must be dominantly s-wave capture, and applying detailed balance, we obtained, with E in eV, σn,γ<930E-1/2 μb. The corresponding limit on the astrophysical reaction rate is <790 cm3 mol-1 s-1. Theoretical predictions of the reaction rate have exceeded our upper limit by factors of 3–50.


©2003 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevC.67.015806
DOI: 10.1103/PhysRevC.67.015806
PACS: 25.60.-t, 97.10.Cv, 26.30.+k, 26.35.+c

* Present address: Wintec Co., Ltd. 4-3-8 Kudan-Kita, Chiyoda, Tokyo 102-0073 Japan.
† Present address: Instituto de Fisica, Universidade de São Paulo, 05315-970 São Paulo-SP-Brasil.
‡ Present address: RIKEN Hirosawa 2-1, Wako, Saitama, 351-0198, Japan.
§ Present address: National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555, Japan.

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