Toward Statistical Properties of Nuclei in the Static-path Plus Random-phase Approximation
Paul Fanto, Yale University
Nuclear-level densities and gamma-ray strength functions are important inputs to the Hauser-Feshbach theory of compound nuclear reactions. Many statistical reaction codes rely on phenomenological parameterizations of these quantities, making it difficult to apply these codes to nuclei for which experimental data is unavailable. Microscopic calculations of these quantities are often obtained using mean-field theory. However, mean-field theory cannot describe certain important correlation effects due to the residual nuclear interaction. The configuration-interaction shell model (CISM) is a useful framework for describing both single-particle and collective motion, but calculations are limited by the combinatorial growth of the many-particle model space. Within the CISM framework, the static-path plus random-phase approximation (SPA+RPA) includes large-amplitude static fluctuations and small-amplitude quantum fluctuations beyond the mean-field approximation. I discuss the application of the SPA+RPA to the calculation of nuclear state densities and gamma-ray strength functions with a quadrupole-quadrupole interaction. In particular, I show that the SPA+RPA describes the rotational enhancement of the level density in a deformed nucleus.
Abstract Author(s): Paul Fanto