COMPLETE CHARACTERIZATION OF BREAKUP OF 9Be BY α-α COINCIDENCE MEASUREMENTS

The breakup mechanisms for Be-9 have been studied through coincident detection of the breakup alpha particles at sub-barrier energies, where the probability of capture of a charged breakup fragment by the target nucleus is negligible. Combining the reconstructed reaction Q-value and the relative energy of the two coincident breakup alpha particles a complete picture of breakup dynamics has been obtained. The measurements reveal breakup processes which are fast enough (similar to 10(-22) s) to affect fusion, called prompt breakup. It is shown that prompt breakup is triggered predominantly by the transfer of a neutron - a two-step process. The prompt breakup probabilities are shown to have an exponential dependence on the surface-to-surface separation of the interacting nuclei, but are independent of the target nuclei, ranging from Sm-144 to Bi-209. These results provide significant input towards a complete quantal model aiming to describe the breakup of weakly bound stable and halo nuclei.