Observation of entrance channel mass-asymmetry effect on incomplete fusion reaction for system

Abstract

Abstract An experiment has been performed to explore the incomplete fusion (ICF) reaction dynamics in heavy ion induced reactions. Excitation functions (EFs) for eighteen evaporation residues (ERs) produced in the system Ne 20 + Ho 165 have been measured in the energy range ≈ 88 – 164 MeV . Some of the ERs have significant contribution from precursor decay, which has been separated out from the measured cumulative cross-sections to get direct production cross-sections. Parameters of the statistical model code PACE-2 are optimized to reproduce the ERs populated in complete fusion reactions such as in xn and pxn channels. Using the same parameters, EFs for the residues produced in α-particle(s) emission channels have been calculated. A significant enhancement in the measured EFs of the ERs produced in α-particle(s) emission channels over the PACE-2 predictions have been observed which indicates the occurrence of incomplete fusion reaction process. In the ICF process the break-up of projectile 20Ne into He 4 + O 16 and/or Be 8 + C 12 takes place followed by fusion of one of the fragments with the target nucleus 165Ho. The present data analyses suggest that probability of incomplete fusion reaction increases with projectile energy. The ICF fraction F ICF has been estimated and found to increase with increasing mass-asymmetry [ A T / ( A T + A P ) ] of the partners in entrance channel. It is also observed that critical angular momentum associated with incomplete fusion channels at higher projectile energy may be associated with l-values lower than that of peripheral collisions, indicating that the incomplete fusion competes with complete fusion even at angular momentum values little lower than critical angular momentum.