Fusion reactions in collisions of neutron halo nuclei with heavy targets

We investigate fusion reactions in collisions of neutron-halo projectiles with heavy targets. For this purpose, we use a recently developed theoretical approach to calculate cross sections for fusion processes in 11Be +209Bi, 6He + 209Bi, and 6He + 238U collisions and compare the results with the available data. The overall agreement between theory and experiment is good. Comparing the cross sections with predictions of a barrier penetration model that ignores the cluster structure of the projectile, we conclude that the fusion cross sections are suppressed above the Coulomb barrier and enhanced below. Further, we find that the deviations from predictions of the barrier penetration model depend exclusively on the breakup threshold of the projectile, increasing as it decreases.