De-excitation of 58,60,62Ni compound nuclei formed via symmetric and asymmetric entrance channels

Abstract

An extensive study of the decay of the compound nuclei 58,60,62Ni formed in the reactions ( 12C + 46Ti), ( 28Si + 30Si), ( 12C + 48Ti), ( 30Si + 30Si), ( 12C + 50Ti), ( 18O + 44Ca) was undertaken in the energy range ~ 0.7 to ~ 1.6 Coulomb barrier in about 20 steps. The fusion cross sections are fragmented in a large number of exit channels, with cross sections from 0.1 to 430 mb. By means of in-beam γ-ray measurements, the evaporation residues were identified both in A and Z. This large data base was compared with fusion-evaporation calculations through individual residue excitation functions and summed evaporation-residue cross sections (resulting from nucleons or α-emission). The model, with a standard set of parameters, does account for the general features of the experimental data, especially for the stronger exit channels. However, these data are not sensitive enough to the presence of other types of mechanisms and must be complemented by other observables to boost the predictive power of the model.