Elastic scattering and α-α coincidence measurements for 9Be + 12C reaction

The 9Be projectile breakup (9Be→8Be+n→α+α + n) has been investigated for 9Be+12C reaction at a bombarding energy ELab = 21 MeV. The 8Be energy spectra were reconstructed using α+α coincidence measurements. A preliminary analysis of these spectra suggests that for the high energy region the main contribution is due to neutron transfer to the 12C target, and the low energy region of the spectrum can be attributed to the 9Be non-capture breakup process. We also measured elastic scattering angular distributions at energies around the Coulomb barrier (ELab = 13, 14.5, 17.32, 19 and 21 MeV) in order to check the possible occurrence of a threshold anomaly in the optical potential. The data were analyzed in the framework of the Sao Paulo potential and, within the experimental uncertainties, the existence of this threshold anomaly could not be confirmed. The experimental elastic scattering angular distributions were well described by the optical potential at forward angles for all measured energies. However, for the three highest energies, an enhancement was observed for intermediate and backward angles. This could be explained by the elastic transfer mechanism. (author)