Direct + Semidirect E1 Photoneutron Reactions: Semimicroscopic Description

The particle-hole dispersive optical model is implemented to describe together E 1 photo-absorption and direct + semidirect photoneutron reactions accompanied by excitation of the giant dipole resonance. Being based on this description, a quantitative estimation of the partial and total branching ratios for direct one-neutron decay of the mentioned giant resonance in a few medium-heavy neutron-closed-shell nuclei is obtained. Calculation results are compared with corresponding experimental data.