Interplay of the elastic and inelastic channels in the O-16+Al-27 scattering at E-lab=280 MeV

Recent data indicated a nuclear rainbow-like pattern in the elastic scattering of O-16 + Al-27 at E-lab = 100 MeV that arises from couplings of the ground to the low-lying states of the Al-27 nucleus. Similar effect was identified in the elastic angular distribution of O-16 + C-12 at E-lab = 281 and 330 MeV. These experiments show a crucial role of microscopic details of nuclear structure in the elastic scattering of heavy ions at energies well above the Coulomb barrier. In this work we investigate the O-16 + Al-27 system at E-lab = 280MeV for which a coupled channel calculation predicts a pronounced nuclear rainbow-like structure. Obtained experimental data show evidences of an important coupling of the elastic channel to the inelastic. Coupled channel calculations reproduce the experimental angular distributions when a renormalization factor on the real part of the optical potential is introduced. A proper theoretical approach still requires a high degree of accuracy for the nuclear structure models and new tools to deal with collective excitations. ZB 0 Z8 0 ZR 0 ZS 0