Description of Radiative and "Weak" Strength Functions of Nuclear Compound States within a Semimicroscopic Approach

A semimicroscopic approach is formulated and applied to a number of nuclei to describe quantitatively photon and "weak" strength functions of nuclear compound stales corresponding to neutron resonances ("weak" transitions imply the P-odd mixing of compound slates with opposite parity). The approach is based on the semimicroscopic consideration of the low-energy "tail" of the corresponding giant resonances by means of both the CRPA description of particle-hole states and the phenomenological description of quasiparticle damping in the framework of an optical model. The temperature version of the approach is used to describe compound-to-compound transitions, whereas the transitions to the ground and low-lying states of nuclei are described within its generalization to the case of nucleon pairing being taken into account. The only adjustable parameter determining the strength of the single-quasiparticle damping is found for each nucleus by comparing the calculated and experimental values of the mean total radiative width of neutron resonances. The results of calculations on the root-mean-squared matrix elements of the parity violating nuclear mean field and E1 and M1 strength functions, corresponding to the gamma-decay of neutron resonances, are compared with the relevant experimental data.