Astrophysical reaction rate for the <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow></mrow><mrow><mn>8</mn></mrow></msup></mrow><mi mathvariant="normal">Li</mi><mo>(</mo><mi>n</mi><mo>,</mo><mi>γ</mi><mrow><msup><mrow><mo>)</mo></mrow><mrow><mn>9</mn></mrow></msup></mrow><mi mathvariant="normal">Li</mi></math></span> reaction

Hiroshi Kobayashi; Kazuo Ieki; Ákos Horváth; Aaron Galonsky; Nelson Carlin; Ferenc Deák; Tomoko Gomi; Valdir Guimaraes; Yoshihide Higurashi; Yoshiyuki Iwata; Ádám Kiss; James J. Kolata; Thomas Rauscher; Hugo Schelin; Zoltan Seres; Robert Warner

doi:10.1103/PhysRevC.67.015806

Astrophysical reaction rate for the $^{8} Li (n, γ)^{9} Li$ reaction

Hiroshi Kobayashi, Kazuo Ieki, Ákos Horváth, Aaron Galonsky, Nelson Carlin, Ferenc Deák, Tomoko Gomi, Valdir Guimaraes, Yoshihide Higurashi, Yoshiyuki Iwata, Ádám Kiss, James J. Kolata, Thomas Rauscher, Hugo Schelin, Zoltan Seres, and Robert Warner

Phys. Rev. C 67, 015806 – Published 23 January 2003

Abstract

An attempt was made to measure the excitation function of the cross section for the $^{8} Li (n, γ)^{9} Li$ reaction by performing the inverse reaction $^{9} Li (γ {, n)}^{8} Li,$ 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 $^{8} Li ’ s$ would be located. Statistically, a Gaussian-shaped $^{8} Li$ peak could have been present with $30 \pm 29$ 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 $^{8} Li$ must be dominantly s-wave capture, and applying detailed balance, we obtained, with E in eV, $σ_{n, γ} < {930 E}^{- 1 / 2} μ b .$ The corresponding limit on the astrophysical reaction rate is $< 790$ ${cm}^{3} {mol}^{- 1} s^{- 1} .$ Theoretical predictions of the reaction rate have exceeded our upper limit by factors of 3–50.

Received 29 October 2002

DOI:https://doi.org/10.1103/PhysRevC.67.015806

Authors & Affiliations

Hiroshi Kobayashi^1,*, Kazuo Ieki¹, Ákos Horváth², Aaron Galonsky³, Nelson Carlin⁴, Ferenc Deák², Tomoko Gomi¹, Valdir Guimaraes^5,†, Yoshihide Higurashi^1,‡, Yoshiyuki Iwata^1,§, 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

^*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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Vol. 67, Iss. 1 — January 2003

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