On Description of Photonuclear Reactions Accompanied by Excitation of the Giant Dipole Resonance

Abstract

A semimicroscopical approach is applied to describe the photoabsorption and partial photonucleon reactions accompanied by excitation of the giant dipole resonance (GDR). The approach is based on both continuum-RPA (CRPA) and a phenomenological description for doorway-state coupling to many-quasiparticle configurations. Apart from a phenomenological mean field, the separable isovector momentum-dependent forces and momentum-independent Landau-Migdal particlehole interaction are used as the input quantities for CRPA calculations. The photoabsorption and partial (n, γ)-reaction cross sections in the vicinity of the GDR are satisfactorily described for 89 Y, 140 Ce and 208 Pb target nuclei. An attempt to evaluate the total direct-neutron-decay branching ratio of the GDR in 48 Ca and 208 Pb is also undertaken.