Fusion of ²⁸Si+⁶⁸Zn, ³²S+⁶⁴Ni, ³⁷Cl+⁵⁹Co and ⁴⁵Sc+⁵¹V in the vicinity of the Coulomb barrier

Abstract

Results of the measurements of fusion excitation functions and average angular momenta are presented for ³⁷Cl+⁵⁹Co, ²⁸Si+⁶⁸Zn, ³²S+⁶⁴Ni and ⁴⁵Sc+⁵¹V, for centre-of-mass energies ranging from ~5 MeV below to ~10 MeV above the Coulomb barrier. These results are discussed in terms of the simplified coupled-channel model and the neutron-flow model due to Stelson. It is pointed out that simplified coupled-channel calculations including collective inelastic excitations alone do not reproduce the observed sub-barrier fusion cross section in most of the cases and that there is a need to include couplings to other channels, like transfer, in order to explain the observations. An analysis of ³²S+⁶⁴Ni fusion excitation data has been performed to derive an empirical barrier distribution in order to investigate the relationship between the simplified coupled-channel model and the neutron-flow model. A simultaneous analysis of the fusion excitation function and average angular momentum seems to indicate that these two quantities are related to each other, as was pointed out by Balantekin and Reimer.