Appliction of Bayes method to optical model parameter estimation for Bi-209 in low energy region.

Abstract

Recently, accurate measurements of angular distribution for neutron elastic scattering have been performed. In these experiments, incident neutron energy intervals are narrow, and the large numbers of experimental data points are evenly distributed from forward to backward angles, so that they make it possible to estimate optical model parameters unambiguously. Bayes method which has been developed to estimate nuclear model parameters in nuclear data evaluation(1) is considered to be applicable to estimation of the optical model parameters.In the present work, new application technique of the Bayes method is developed to estimate the optical model parameters and to investigate energy dependence of the optical model parameters. A demonstration is made for 209Bi, with the angular distribution of elastic scattering and an evaluated total cross section. Because, 209Bi is generally treated as a spherical nucleus and has relatively high level density near the neutron binding energy. Therefore, these characteristics simplify the analysis of low energy scattering data, and this nucleus is suitable to examine an applicability of the Bayes method to the optical model parameter estimation.