Shell-correction approach to nuclear state densities and the competition between fission and neutron emission of 210Po

Abstract

Starting from the Hartree-Fock approximation to the grand canonical partition function we formulate a consistent renormalization of the ground-state energy and the intrinsic state density as a function of deformation. The competition between fission and neutron emission, Γ f Γ n (E) , of 210Po is studied within the framework of the statistical theory as an example. Calculations using renormalized state densities are compared with usual shell-model calculations and experimental data. We find that the usual calculations reflect the incorrect uniform deformamation dependence of the shell-model spectral function. As important changes due to renormalization we find: there is a rapid change of the shape of the transition state at ≈ 45 MeV excitation energy, Γ f Γ n (E) remains smaller than unity for all excitation energies and the deformation of the transition state increases after the “shape transition” at 45 MeV monotonically towards the liquid drop saddle-point deformation.