Global α - nucleus optical model based on an Dirac Brueckner Hartree Fock approach

The global α-nucleus optical model is studied based on the nucleon self-energies in an Dirac-Brueckner-Hartree-Fock (DBHF) approach. The newly developed nucleon-nucleus optical model CTOM derived from DBHF, is used as the basis to consistently generate the real and imaginary potentials of the α-nucleus optical potential by double-folding model. The same range correction a of the improved local density approximation (ILDA) in CTOM is adopted, which is also suitable to modify the nucleon interaction range in α-nucleus systems. To get better description of experimental data, the re-normalization factors (N_R,N_I) are introduced in α-nucleus scattering calculations, and the individual optimized (N_R,N_I) for all nuclei and energies are searched out under the guidance of χ² criterion. We systematically explore the energy dependence of N_R and N_I by considering the α elastic scattering from ¹²C to ²⁰⁸Pb at incident energies below 120MeV/nucleon and a simple exponential function is extracted. With this global α-nucleus optical potential, a reasonable description of all available experimental data for α scattering from nuclei is achieved.