Structure and decay properties of spin-dipole giant resonances within a semimicroscopical approach

A semimicroscopical approach is applied to calculate: (i) strength function s for the charge-exchange spin-dipole giant resonances in the Pb-208 parent nucleus; (ii) partial and total branching ratios for the direct proton dec ay of the resonance in Bi-208. The approach is based on continuum-RPA calcu lations of corresponding reaction-amplitudes and phenomenological descripti on of the doorway-state coupling to many-quasiparticle configurations. The only adjustable parameter needed for the description is found by comparison of the calculated and experimental total widths of the resonance. Other mo del parameters used in calculations are taken from independent data. The ca lculated total branching ratio is found to be in reasonable agreement with the experimental value. (C) 1999 Published by Elsevier Science B.V. All rig hts reserved.