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New indirect study of the 12C(α,γ)16O reaction via the 12C(7Li,t)16O transfer reaction

par Hammache, Fairouz;Oulebsir, N.;Roussel, Pierre;Pellegriti, Maria Grazia;Audouin, Laurent;Beaumel, D.;Fortier, Simone;Bouda, A.;Descouvemont, Pierre ;Gaudefroy, Laurent;Kiener, Jürgen;Lefebvre-Schuhl, A.;Tatischeff, Vincent
Référence Pos proceedings of science
Publication Publié, 2012

Article révisé par les pairs

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Résumé :

The radiative capture reaction 12C(α, γ) 16O plays a key role in stellar nucleosynthesis and evolution. However the cross section of this reaction at stellar energies remains highly uncertain despite various experimental studies. The extrapolation down to stellar energy (Ecm∼300 keV) of the measured cross sections at higher energies is made difficult by the overlap of various contributions of which some are badly known such as that of the 2+ (Ex=6.92 MeV) and 1- (Ex=7.12 MeV) sub-threshold states of 16O. Indeed, the α-reduced widths and so the α-spectroscopic-factors of these two sub-threshold states are spread over too-large a range of values. Accordingly, a new determination of these quantities through 12C(7Li,t)16O transfer reaction measurements at two incident energies and a detailed DWBA analysis of the data was performed recently at Orsay. The measured and calculated differential cross sections are presented as well as the obtained spec-troscopic factors and the α-reduced widths for the 2+ and 1- sub-threshold states. The R-matrix calculations of the 12C(α, γ)16O cross section using our obtained α-reduced widths for the two sub-threshold resonances are presented and discussed. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.