SUB-BARRIER FUSION OF DRIP-LINE NUCLEI

We discuss the role of break-up process of a loosely-bound projectile in subbarrier fusion reactions. Coupled-channels calculations are carried out for $^{11}$Be + $^{208}$Pb and $^{4,6}$He + $^{238}$U reactions by discretizing in energy the particle continuum states. Our calculations show that the coupling to the break-up channel has two effects, namely the loss of flux and the dynamical modulation of fusion potential. Their net effects differ depending on the energy region. At energies above the Coulomb barrier, the former effect dominates over the latter and cross sections for complete fusion are hindered compared with the no coupling case. On the other hand, at below the barrier, the latter effect is much larger than the former and complete fusion cross sections are enhanced consequently.