Insights into the influence of breakup on fusion through reactions with weakly bound stable nuclei

Abstract

Complete fusion of 6Li, 7Li, and 9Be with targets of 208Pb and 209Bi are found to be suppressed by about 30% at energies above the fusion barrier. Sub-barrier break-up measurements for the 9Be + nat Pb reaction show that prompt breakup of 9Be occurs close to the nuclear surface, and with sufficient probability to explain the suppression of complete fusion. The suppression is predicted to be proportional to the charge of the target nucleus. A simple classical trajectory model which makes the distinction between complete and incomplete fusion shows that following breakup of the projectile close to the target, there is a significant probability of capture of all fragments by the target. This implies that fusion of exotic nuclei far from the line of stability may not be seriously suppressed by breakup.