Coulomb- and nuclear-induced break-up of halo nuclei at bombarding energies around the Coulomb barrier

We investigate the relative importance of the Coulomb and nuclear fields to induce the break-up of neutron-rich nuclei such as Li-11 at energies close to the Coulomb barrier. We assume that the mechanism that leads to the separation is the excitation of a low-lying dipole mode in which the weakly-bound neutron halo performs a collective oscillation against the residual nuclear core. To this end we exploit semiclassical prescriptions that are adequate to calculate not only the average break-up probabilities but also to estimate the size of fluctuations about the quantal expectation values. Possible outcomes are explored as a function of both bombarding energy and impact parameter. Consequences of the couplings for elastic scattering and fusion processes are also discussed.