Measurement of excitation functions of evaporation residues in the O-16 + Sn-124 reaction and investigation of the dependence of incomplete fusion dynamics on entrance channel parameters

摘要

Excitation functions for the 11 evaporation residues populated through complete and/or incomplete fusion in O-16 + Sn-124 system at low projectile energies approximate to 3-7 MeV/nucleon have been measured. Recoil catcher activation technique followed by offline gamma-ray spectrometry has been employed. Some of the evaporation residues are found to have contributions from precursor decays. The precursor contributions have been separated out from the measured cumulative cross-sections of evaporation residues. Independent cross-sections are compared with statistical model code PACE-4 predictions. The evaporation residues produced through xn and pxn channels are found to be well reproduced with the PACE-4 predictions after subtraction of precursor decay contributions. A substantial enhancement in the measured excitation functions over their theoretical predictions for the evaporation residues produced in alpha-emitting channels has been observed, which is attributed to the presence of incomplete fusion of projectile with target at these low energies. The present study shows that the incomplete fusion and the break-up probability of the incident O-16 into alpha clusters (i.e., break-up of O-16 into C-12 + alpha and/or Be-8+Be-8) increases with projectile energy. The present data suggests that the deformation of target is highlighting the important role to affect the ICF reactions independently with different projectiles. The comparison of the present study with literature data also shows that the ICF probability depends on various entrance channel parameters, namely, projectile energy, entrance channel mass-asymmetry, alpha-Q value, Coulomb factor (Z(P)Z(T)), deformation parameter (beta(2)), and their combinations. Moreover, the combined parameters Z(P)Z(T) . beta(2) and mu(AS)(EC) . beta(2) are not found suitable to explain whole ICF characteristics, particularly for spherical and slightly deformed targets. On the other hand, the combined parameter Z(P)Z(T) . mu(AS)(EC) has been found to explain more precisely the ICF dynamics as compared to other single and combined entrance channel parameters.