Bochum 1998 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
HK: Hadronen und Kerne
HK 53: Nuclear Astrophysics IV
HK 53.1: Group Report
Wednesday, March 18, 1998, 14:00–14:30, G
Microscopic models for nuclear astrophysics — •P. Descouvemont1 and Physique Nucléaire Théorique2 — 1Service de Physique Nucléaire Théorique et Physique Mathématique CP-229, Université Libre de Bruxelles, B-1050 Brussels — 2
We present different applications of the Generator Coordinate Method (GCM) to reactions of astrophysical interest (radiative capture and transfer reactions) [1]. In the GCM, all nucleon coordinates are included in the hamiltonian, and the wave functions of the system are defined from antisymmetrized products of cluster wave functions. The cluster model offers a number of important advantages for low-energy reactions: (i) Antisymmetrization between all the nucleons is exactly taken into account; (ii) Good quantum numbers, such as spin and parity, are treated without approximation; (iii) Bound and scattering states are treated in a unified way.
This last property is extremely useful for testing the validity of theoretical cross sections from spectroscopic properties of the unified nucleus. The complexity of microscopic models is therefore largely compensated by their predictive power since the input data are limited to a nucleon-nucleon interaction, and to a few assumptions concerning the cluster structure of the system.
After a brief overview of the GCM, we present different applications on reactions of astrophysical interest (for instance 8Li(α,n)11B [2] and 12C(p,γ)13N [3]). We present a new microscopic approach [2], where all 8Li and 11B p-shell configurations are included. The model is tested on the 12B spectroscopy, and then applied to the 8Li(α,n)11B cross section.
The second example deals with the 12C(p,γ)13N and 12C(n,γ)13C reactions, which are studied in an (α + α + α) + p (or n) multicluster model [3]. The neutron capture cross section is shown to be sensitive to the halo structure of the 1/2+ (Ex=3.09 MeV) state.
[1] P. Descouvemont, Proc. Int. Conf. Nuclei in the Cosmos II, Karlsruhe (1992), J. Phys. G19, S141 (1993)
[2] P. Descouvemont, Nucl. Phys. A596, 285 (1996)
[3] M. Dufour and P. Descouvemont, Phys. Rev. C (1997), in press