MICROSCOPIC SHELL-MODEL AND CLUSTER-MODEL CALCULATIONS OF THE C-13-]C-12+N AND B-8-]BE-7+P VERTEX CONSTANTS

摘要

Vertex constants are calculated with an effective nucleon-nucleon interaction and translation-invariant harmonic-oscillator shell-model wave functions consistently obtained with the same interaction. Such calculations are presented for the C-13 --> C-12 + n vertex constant for which an accurate experimental value is available, and for the B-8 --> Be-7+p vertex constant, which is crucial for the determination of the Be-7(p,gamma)B-8 reaction at astrophysical energies. Calculations confirm the strong sensitivity of vertex constants to the choice of the effective nucleon-nucleon interaction. A comparison of vertex constants obtained in the shell-model approach and in microscopic two- and three-cluster models with identical nucleon-nucleon potentials shows that the main contribution to the cluster-model vertex constants comes from the shell-model parts of the cluster-model wave functions. The reliability of model calculations of the 7Be(p,gamma)B-8 astrophysical S factor is discussed. (C) 1997 Elsevier Science B.V. [References: 36]