Complementary optical-potential analysis of -particle elastic scattering and induced reactions at low energies

A previously derived semi-microscopic analysis based on the Double Folding Model, for α -particle elastic scattering on A ∼ 100 nuclei at energies below 32 MeV, is extended to medium mass A ∼ 50 – 120 nuclei and energies from ∼13 to 50 MeV. The energy-dependent phenomenological imaginary part for this semi-microscopic optical model potential was obtained including the dispersive correction to the microscopic real potential, and used within a concurrent phenomenological analysis of the same data basis. A regional parameter set for low-energy α -particles entirely based on elastic scattering data analysis was also obtained for nuclei within the above mentioned mass and energy ranges. Then, an ultimate assessment of ( α , γ ) , ( α , n ) , and ( α , p ) reaction cross sections considered target nuclei from 45Sc to 118Sn and incident energies below ∼12 MeV. The former diffuseness of the real part of optical potential as well as the surface imaginary potential depth have been found to be responsible for the actual difficulties in the description of these data, and modified in order to obtain an optical potential which describes equally well both the low-energy elastic scattering and induced reaction data for α -particles.