Understanding the interplay between sub–barrier breakup of Li and above-barrier suppression of complete fusion

With the discovery of halo nuclei, and recent intensive development of radioactive ion beams (RIBs) around the world, there is renewed interest in studying interaction of weakly-bound light nuclei as a basis for understanding interactions of halo nuclei and RIBs. Using a novel experimental approach [1], reactions of the weakly–bound nuclei Be and Li with heavy targets consistently showed suppression of complete fusion by ∼30% [2, 3]. The low threshold energies for breakup of Li and Be are widely associated with their observed suppression of complete fusion [1–5], with breakup described as cluster decay from unbound states independent of the mechanism that populates it [6–12]. However, knowing the reaction processes leading to breakup is not sufficient to understand the interplay between breakup and suppression of fusion [3]. It is critical to also know the timescale of each process [13], whether the breakup occurs before or after the projectile reaches its point of closest approach to the target nucleus.