A. Mukherjee

Suppression of complete fusion due to breakup in the reactions 10,11 B + 209 Bi

Above-barrier cross sections of fission and {alpha}-active heavy reaction products were measured for the reactions of {sup 10,11}B with {sup 209}Bi. Systematic analysis showed that the fission originates almost exclusively from complete fusion (CF). Existing measurements of above-barrier fusion products for the {sup 30}Si+{sup 186}W reaction, assumed to proceed exclusively through CF, were extrapolated to the current systems using statistical model calculations. This extrapolation showed that the heavy reaction products from the {sup 10,11}B+{sup 209}Bi reactions include substantial components from incomplete fusion as well as from CF. Compared with fusion calculations without breakup, the CF cross sections are suppressed by 15% for {sup 10}B and 7% for {sup 11}B. A consistent and systematic variation of the suppression of CF for reactions of the weakly bound nuclei {sup 6,7}Li, {sup 9}Be, and {sup 10,11}B on targets of {sup 208}Pb and {sup 209}Bi is found as a function of the breakup threshold energy.

Absence of fusion suppression due to breakup in the 12C + 7Li reaction

Abstract The fusion cross-section for 12C + 7Li has been determined, using a 12 C beam, at an energy near the Coulomb barrier. Previous measurements showed a large discrepancy in cross-sections, leading to conflicting conclusions regarding fusion suppression due to breakup. The present work resolves this discrepancy, and shows that there is no significant inhibition of fusion near the barrier.

Inhibition of Fusion in Mass-Asymmetric Collisions

Comprehensive fission and evaporation residue measurements have been made for three reactions, all of which lead to the 216Ra compound nucleus, at energies from the Coulomb barriers upwards. The results show inhibition of fusion and the increasing presence of quasi-fission with decreasing mass-asymmetry of the projectile and target combination in the entrance channel. This work demonstrates a lower threshold for the inhibition of fusion and the onset of quasi-fission than previously expected.