Systematic analysis of inelastic α scattering off self-conjugate A=4n nuclei

We systematically measured the differential cross sections of inelastic a scattering off self-conjugate A = 4n nuclei at two incident energies Ea = 130 MeV and 386 MeV at Research Center for Nuclear Physics, Osaka University. The measured cross sections were analyzed by the distorted-wave Born-approximation (DWBA) calculation using the single-folding potentials, which are obtained by folding macroscopic transition densities with the phenomenological alpha N interaction. The DWBA calculation with the density-dependent aN interaction systematically overestimates the cross sections for the Delta L = 0 transitions. However, the DWBA calculation using the density-independent aN interaction reasonably well describes all the transitions with Delta L = 0-4. We examined uncertainties in the present DWBA calculation stemming from the macroscopic transition densities, distorting potentials, phenomenological aN interaction, and coupled channel effects in C-12. It was found that the DWBA calculation is not sensitive to details of the transition densities nor the distorting potentials, and the phenomenological density-independent aN interaction gives reasonable results. The coupled-channel effects are negligibly small for the 2(1)(+) and 3(1)(-) states in C-12, but not for the 0(2)(+) state. However, the DWBA calculation using the density-independent interaction at Ea = 386 MeV is still reasonable even for the 0(2)(+) state. We concluded that the macroscopic DWBA calculations using the density-independent interaction are reliably applicable to the analysis of inelastic a scattering at E alpha similar to 100 MeV/u.