A parameter estimation method based on Bayes' theorem is applied to the parameters of the neutron optical potential for 209Bi. The potential parameters at a certain energy are determined according to an assumption that parameters vary gradually with the incident neutron energies, and it is demonstrated that the method can be used as an efficient tool for investigating the energy dependence of the optical potential parameters.

The derived potential parameters are expressed by both a polynomial function and a Brown-Rho parameterization, and the energy dependencies are interpreted by a dispersion relation theory. Both expressions of the energy-dependent parameters give a good description of the experimental elastic scattering cross section and the total cross section.