Experimental estimates of the parameters of the cascade γ-decay of heavy compound nuclei. The most probable energy dependence of the radiative strength functions of dipole transitions at 0.52 MeV ≤Eγ<Bn

An analysis of the intensities of the two-step γ-cascades in a large group of nuclei from the mass region 114≤A≤200 allowed determination of the probable level density excited after thermal neutron capture and sum of the radiative strength functions for the E1 and M1 primary transitions in the excitation energy range, practically, up to Bn. These data permits also reproducing experimental values of the total radiative widths of neutron resonances in nuclei under study. The analysis showed that the strength function models pretending to better agreement with reality should provide more correct accounting for the structures of the states connected by the γ-transitions following the decay of neutron resonance. The simplest explanation of the observed energy dependence of both level density and strength functions is the change in the ratio of quasiparticle and variational components in wave functions of the states excited by the primary transitions. This follows from the notions of the generalized model of the superfluid nucleus, from the observed harmonicity in the excitation spectra of intermediate levels of the most intense cascades, and considerable enhancement of the radiative strength functions with respect to predictions of conventional models. Impossibility of simultaneous reproduction of the total radiative widths and two-step cascade intensity testifies that, below the neutron binding energy, nucleus cannot be considered as a system of noninteracting Fermi-particles. (author)