It is shown that the behaviour of the fusion excitation functions for proton-halo and neutron-halo systems presents important differences, especially in the energy region slightly above the barrier. Measurements for 6He, 11Li and 11Be projectiles are discussed to exemplify the behaviour of neutron-halo systems, while experiments with 8B beams illustrate the situation for proton-halo nuclei. With respect to a standard benchmark, neutron- (proton-) halo systems show a fusion suppression (enhancement) above the barrier.
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