Suppression of fusion by breakup: Resolving the discrepancy between the reactions of 9 Be with 208 Pb and 20 9Bi

Abstract

Complete fusion cross sections for Be9 incident on Pb208 and Bi209 have been measured at energies greater than the fusion barrier to investigate the large differences in their reported complete fusion cross sections. Relative xn and fission cross sections are in good agreement. Thus, it is concluded that the differences arise from errors in absolute normalization in the previous measurements. The present measurements show that the above-barrier complete fusion cross sections for the reactions of Be9 with Bi209 and Pb208 are very similar, which resolves the previously observed anomaly. Complete fusion for the reaction of Be9 with Bi209 is found to be suppressed by ∼32% compared to the expectations of a single-barrier penetration model, which is in close agreement with the value previously determined for the reaction with Pb208.