Time-scales and Mechanisms of Breakup Influencing Fusion

Coincidence measurements of breakup of Li-6,Li-7 and Be-9 incident on various high-Z targets have provided a complete picture of the physical mechanisms triggering breakup. The measurements identify those breakup processes that are fast enough (10(-22) s) to affect fusion. The majority of these prompt breakup events are triggered by transfer of a neutron from Li-6, Be-9, and of a proton to Li-7. The dominance of breakup following transfer demonstrates that the reaction outcomes involving weakly bound nuclei depend not only on the properties of the two colliding nuclei, but also on the ground-state and excited state properties of their neighbours. This is a key insight for understanding and predicting reactions of weakly-bound nuclei near the limits of nuclear existence.