Elastic scattering for the B 8 and Be 7 + Pb 208 systems at near-Coulomb barrier energies

The elastic scattering of the weakly bound radioactive nuclei B8 and Be7 from a Pb208 target was measured for the first time in the energy range around the Coulomb barrier. The data were analyzed using the optical model and the continuum discretized coupled channels (CDCC) formalisms. The reaction cross sections extracted from the optical model fits clearly indicate a remarkably enhanced reaction probability for the very weakly bound B8 (Sp=137.5keV) compared to similar mass nuclei interacting with the same target nucleus. CDCC calculations assuming a He3+He4 cluster model well described the Be7 experimental elastic scattering angular distributions, whereas the use of a Be7+p cluster model of B8 with an inert Be7 core gave a relatively poor description of the corresponding experimental data, suggesting that this model may be too simplistic and the possibility of core excitation should not be ignored.