We have proposed an energy-dependent parametrization scheme for determining the diffuseness parameter of Woods–Saxon potential which when used in conjunction with the coupled channel code CCFULL explains very well the fusion excitation function data around the barrier for various systems.

We have studied the effects of the finite range of the interaction between the fragments of the projectile on the fusion and/or breakup of 6 He+ 238 U and 11 Li+ 208 Pb systems at near barrier energies within the framework of dynamic polarization potential approach. It has been found that at near barrier energies the maximum flux is lost to the breakup channel and at energies well above the Coulomb barrier the fusion coupled with the breakup channel opens up, initially with sharp rise and later becoming saturated at energy nearly twice of the Coulomb barrier. Further, it is found that the breakup cross section increases with the increasing range of the interaction between the fragments of the projectile while the fusion coupled with the breakup channel cross section decreases with the increasing range.

We have studied the role of spatial extension (Halo structure) of 6 He and that of breakup reaction channel in the fusion of 6 He +238 U system. The breakup channel effects are taken into account within the framework of the dynamic polarisation potential approach. It has been found that the fusion cross section enhances due to the static effects of spatial extension of the projectile in the entire energy region. The breakup effects, however, results in the above barrier suppression and below barrier small enhancement in the fusion cross section. The matching between the data and the predictions improves significantly by the inclusion of both static and breakup effects.

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