3. DESCRIPTION OF PROGRAM OR FUNCTION
The complete program calculates the fast neutron data of medium-heavy nuclei. It includes: the total cross sections, elastic scattering cross section, nonelastic cross section, total inelastic cross section, (n,2n) and (n,3n), cross section, (n,n'x) cross section where x may be alpha, p, d, t and He3, (n,n') cross section for leaving the residual nucleus in from the first up to the 40th excited state and the continuum state, radiative capture cross section, (n,x) cross section where x may be p, d, t, He3 and alpha, (n,2alpha) and (n,2p) cross section, (n,px) cross section where x may be alpha, d, t and He3, (n,alphax) cross section where x may be d and t, the average cosine of the scattering angle (laboratory system) for elastic scattering, the average logarithmic energy decrement for elastic scattering, the average of the square of the logarithmic energy decrement for elastic scattering divided by twice the average logarithmic, the (n,x) cross section for leaving the residual nucleus in from the ground state up to be 17th excited state and in the continuum state where x may be p, d, t, He3 and alpha. The elastic scattering angular distribution and inelastic scattering angular distribution for leaving the residual nucleus in the first up to 40th excited state. The (n2n), (n,3n), (n,n'x) reactions, where x may be alpha, p, d, t
and He3 and the inelastic scattering secondary neutron spectra. All nuclear data are given for the natural elements as well as their isotopes and their output is according to ENDF/B-IV format. The incident neutron energy region, where 150 energy points at most may be included, is from 1 KeV to 20 MeV. The program includes the optical model, width fluctuation corrected Hauser-Feshbach formula and preequilibrium statistical theory based on the exciton model. The experimental direct reaction component of the inelastic scattering projectile exciting from the first up to the 4th excited state may be placed in the input. These are added to the calculated compound nucleus cross sections with a given weight. All nuclear level densities required are calculated according to the formulation of A. Cameron. The transmission coefficients or inverse cross sections of the particles used in statistical theory are calculated by the optical model. The gamma-ray transmission coefficients are calculated based on the giant dipole resonance model. The optical potentials used are Wood- Saxon for the real part, Wood Saxon and derivative Wood-Saxon for the imaginary part corresponding to the volume and surface absorptions respectively, and Thomas form for the spin-orbit part. For some special elements of which the experimental data are unknown, this program provides a microscopic optical potential calculation with skyrme forces for neutron or proton channels.