Shell-corrected particle-hole state densities for pre-equilibrium reaction calculations

Abstract

Calculated particle-hole state densities in the shell-shifted equi-spacing model (s2-ESM) potentially provide a fast and simple way to consistently include shell structure effects in pre-equilibrium reaction calculations. Results from the existing state density formalism were compared with results from the exact counting of states, and the methodology for evaluating the effective single particle state densities in the s2-ESM state density formula was completely revised. Calculated state densities were then compared with literature results obtained from more realistic sets of single particle states, indicating the model's utility. Finally, model-independent estimates of the sizes of the shell gaps were obtained from a set of nuclear mass tables so that the s2-ESM can be used in reaction calculations without the introduction of any new free parameters.