Significant features of 8 B scattering from 208 Pb at 170 . 3 MeV

The scattering of proton-halo nucleus 8B from 208Pb at 170.3 MeV is shown to reveal a distinctive pattern in the change in |SL| that is induced by coupling to breakup channels. The same pattern had been found for 8B scattering from 58Ni at 30 MeV, an energy near the Coulomb barrier, and has been linked to various other respects in which scattering for this proton-halo nucleus differs from that of other light, weakly bound nuclei. The increase in |SL| for L < 80, induced by breakup coupling, is associated with a substantial repulsive region in the dynamic polarization potential as determined by exact inversion. This repulsion appears to reduce the penetration of the projectile into the absorptive region of the interaction. This accounts for the fact that the increase in the total reaction cross section, due to breakup, is much less than the breakup cross section, and is consistent with the relatively small effect of breakup on the elastic scattering angular distribution compared with the large breakup cross section.