Experimental measurements of the differential cross sections for the production of gamma rays in natural silicon and tungsten in the energy range from 5.0 to 11.0 MeV are presented. Theoretical calculations of the production cross sections for silicon, based on statistical theory and the Satchler formalism, with modifications by Moldauer, have been made, and comparisons of these calculations and other nuclear model calculations with experiment are discussed.
Neutron-induced cross sections on tungsten isotopes were calculated in the energy range between 1 and 20 MeV using preequilibrium-statistical model techniques. The success of these calculations, which form part of an effort to improve the evaluated neutron and gamma-ray production cross sections for tungsten appearing in ENDF/B, depends strongly on the determination of consistent input parameter sets applicable over the entire range of interest. For example, neutron optical model parameters were derived through a simultaneous analysis of total cross sections, resonance data, and angular distributions. These parameters, when used in multistep Hauser-Feshbach calculations, produce good agreement with varied experimental data such as neutron inelastic scattering excitation functions and (n, 2n) cross sections. Likewise, gamma-ray strength functions were determined through fits to neutron capture data that produce calculated results that compare well to measured gamma-ray production cross sections. A description of the techniques used in such parameter determinations as well as comparison of calculated results to experimental data will be presented.
