Is a global coupled-channel dispersive optical model potential for actinides feasible?

An isospin-dependent coupled-channel optical model potential containing a dispersive term with a nonlocal contribution is used to simultaneously fit the available experimental database (including strength functions and scattering radius) for neutron and proton scattering on strongly deformed ${}^{238}\mathrm{U}$ and ${}^{232}\mathrm{Th}$ nuclei. The energy range 0.001–200 MeV is covered. A dispersive coupled-channel optical model (DCCOM) potential with parameters that show a smooth energy dependence and energy-independent geometry are determined from fits to the entire data set. Calculations using the obtained DCCOM potential reproduce measured total cross-section differences between ${}^{232}\mathrm{Th}$ and ${}^{238}\mathrm{U}$ within experimental uncertainty. The isovector terms and the observed very weak dependence of the geometrical parameters on mass number A allow us to extend the derived potential parameters to neighboring actinide nuclei with great confidence.

Figure 1

(Color online) Energy dependence of the measured ratio $[\sigma ({}^{238}U)-\sigma ({}^{232}\mathrm{Th})]/\{[\sigma ({}^{232}\mathrm{Th})+\sigma ({}^{238}U)]/2\}$ versus calculated values obtained with different OMPs (the corresponding RIPL OMP index [38] is indicated in parentheses).