Separation approximation in the continuum shell model and application to the giant resonance of 12C

Abstract

An approximation scheme for treating the coupled-channel equations in the continuum shell model is presented. The method is based on an expansion of the single-particle continuum functions in terms of a discrete set of basis states in the region of strong nuclear interactions. This approach is applied to the description of the photonuclear giant resonance of 12C. The giant dipole states of this nucleus are described by coupling a 2s or ld particle to the low-lying normal-parity states of the residual nuclei 11B and 11C. The ground state of 12C and the states of the residual mass-11 nuclei are taken from a lp shell intermediate coupling calculation. The results are compared with the predictions of the simple lp-lh model and with experimental data.