par Baye, Daniel Jean 
Référence Understanding radiative-capture reactions at very low energies, Nova Science Publishers, New York, Vol. The Universe Evolution: Astrophysical and Nuclear Aspects, Ed. 1, The Universe Evolution: Astrophysical and Nuclear Aspects, page (185-215)
Publication Publié, 2013
Référence Understanding radiative-capture reactions at very low energies, Nova Science Publishers, New York, Vol. The Universe Evolution: Astrophysical and Nuclear Aspects, Ed. 1, The Universe Evolution: Astrophysical and Nuclear Aspects, page (185-215)
Publication Publié, 2013
Partie d'ouvrage collectif
| Résumé : | Radiative-capture reactions are studied in the potential model at very low energies including energy zero. For the capture of charged particles, the astrophysical S factor possesses a Taylor expansion in powers of the energy of the relative motion. By using scaled scattering functions with a finite non-zero limit at energy zero, the S factor is obtained in the potential model from a simple integral which allows visualizing its behaviour at energies close to zero. The first coefficients of this expansion can be calculated accurately from solutions of the Sc equation and its derivatives with respect to energy, at energy zero. The 3He(alpha,gamma)7Be and 7Be(p,gamma)8B reactions are used as illustrative examples. The same approach applies to the proton-proton weak capture. For neutron radiative capture, the product $sigma v$ of the capture cross section and the relative velocity also possesses a Taylor expansion in powers of the energy, which can be treated in a similar way. The neutron capture by 12C, 14C and 16O are used as examples. The extension of these treatments to microscopic models of radiative capture is discussed in the context of the R-matrix theory. |
