Speaker
Description
In this work, we compare the performance of three well-known phenomenological nuclear level density models for cross-section evaluations in the unresolved resonance region. Phenomenological model parameters are optimized by using least-squares analysis to simultaneously fit level density, cross-section, neutron strength, and capture width data from the EXFOR and ENSDF databases. Calculations are accomplished using the Hauser-Feshbach model and a novel implementation of the Back-Shifted Fermi Gas Model, Gilbert-Cameron Composite Model, and Generalized Superfluid Model in the cross-section evaluation code SAMMY. We evaluate model performance by examining both the goodness of fit to experimental data and the propagation of model differences to shielding and critical benchmark simulations. Based on agreement with experimental benchmark results, recommendations are made to evaluators on level density model choice.