Elastic scattering for the B8 and Be7+Pb208 systems at near-Coulomb barrier energies

The elastic scattering of the weakly bound radioactive nuclei B-8 and Be-7 from a Pb-208 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 B-8 (S-p = 137.5 keV) compared to similar mass nuclei interacting with the same target nucleus. CDCC calculations assuming a He-3+He-4 cluster model well described the Be-7 experimental elastic scattering angular distributions, whereas the use of a Be-7+p cluster model of B-8 with an inert Be-7 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.