Astrophysical factor for the neutron generator 13C(alpha,n)16O reaction in the AGB stars

E. D. Johnson, G. V. Rogachev, A. M. Mukhamedzhanov, L. T. Baby, S. Brown, W. T. Cluff, A. M. Crisp, E. Diffenderfer, V. Z. Goldberg, B. W. Green, T. Hinners, C. R. Hoffman, K. W. Kemper, O. Momotyuk, P. Peplowski, A. Pipidis, R. Reynolds, B. T. Roeder

Submitted on 18 May 2006


The reaction 13C(alpha,n) is considered to be the main source of neutrons for the s-process in AGB stars. At low energies the cross section is dominated by the 1/2+ 6.356 MeV sub-threshold resonance in 17O whose contribution is determined with a very large uncertainty of ~1000% at stellar temperatures. In this work we performed the most precise determination of the low-energy astrophysical S factor using the indirect asymptotic normalization (ANC) technique. The alpha-particle ANC for the sub-threshold state has been measured using the sub-Coulomb alpha-transfer reaction (6Li,d). Using the determined ANC we calculated S(0), which turns out to be an order of magnitude smaller than in the NACRE compilation.


Comment: 4 pages, 4 figures

Subjects: Nuclear Experiment; Astrophysics