Polarized proton scattering on Ni at small momentum transfer: A test of the microscopic optical model and effective interactions

The reaction 58Ni(p→,p→′) has been studied at small scattering angles and an incident beam energy of 172 MeV. We extract cross sections and analyzing powers for elastic scattering and transitions to vibrational states at low excitation energies. The data are compared to DWBA98 calculations using different widely used effective projectile–target interactions and the quasiparticle–phonon model including complex configurations for the nuclear structure input. The comparison with the experimental data reveals surprising discrepancies for elastic scattering observables at forward angles, whereas the prominent inelastic transitions to low-lying states are well described.