Observation of incomplete fusion reactions at ? < ?_(crit)

摘要

In order to understand the presence of incomplete fusion at low energies i.e. 4-7MeV/nucleon & also to study its dependence on various entrance-channel parameters, the two type of measurements (i) excitation function for ~(12)C+~(159)Tb, and (ii) forward recoil ranges for ~(12)C+~(159)Tb systems have been performed. The experimentally measured excitation functions have been analyzed within the framework of compound nucleus decay using statistical model code PACE4. Analysis of data suggests the production of xn/pxn-channels via complete fusion, as these are found to be well reproduced by PACE4 predictions, while, a significant enhancement in the excitation functions of α-emitting channels has been observed over the theoretical ones, which has been attributed due to the incomplete fusion processes. Further, the incomplete fusion events observed in case of forward recoil range measurements have been explained on the basis of the breakup fusion model, where these events may be attributed to the fusion of 8Be and/or ~4He from ~(12)C projectile to the target nucleus. In the present work, the SUMRULE model calculations are found to highly underestimate the observed incomplete fusion cross-sections which indicate that the ?-values lower than ?crit (limit of complete fusion) significantly contribute to the incomplete fusion reactions.