G.H.D. pre-equilibrium emission model and statistical model parameters for structural material fast neutron data calculations

Inclusion of the angular momentum conservation in the Geometry Dependent Hybrid (GDH) pre-equilibrium emission subroutine of the Hauser-Feshbach code STAPRE is discussed. The consistency of the statistical model nuclear level density and the equivalent particle-hole state density has been achieved following a unitary use of an energy dependent level density parameter. The neutron and charge particles optical model potentials selected from literature are commented. The E1 gamma-ray strength functions, used in the gamma-ray transmission coefficient evaluation, have been taken from an empirically modified energy-dependent Breit-Wigner (EDBW) model. The proper account of the nuclear level density over a large energy range has been obtained through the use of the empirical back-shifted Fermi gas (BSFG) model, at medium excitation energies, and of a realistic analytical formula with microscopic suggested parameters at the high excitation energies. The necessary transition excitation range between the two different density approaches, in the mass range 40<A<65, has been discussed. (author). 30 refs, 3 figs