Investigation of Channel Coupling Effects in Interactions of 19F with 64,68Zn Around the Coulomb Barrier

Abstract

The present work investigates heavy-ion fusion and nucleon transfer reactions in collisions of 19F with 64,68Zn at energies around the Coulomb barrier. The sub-barrier fusion cross-sections are found to be enhanced as compared to single barrier model calculations. The enhancement is attributed to the channel coupling effects, which may arise due to the non-spherical geometry of nuclei and nucleon transfer between the reactants. The fusion cross-section measurements are performed for 19F + 64,68Zn systems at energies ∼ 15% below to ∼ 20% above the Coulomb barrier. The experimentally obtained cross-sections are analyzed using quantum mechanical and semi-empirical coupled-channels codes. The calculations, including coupling to inelastic excita- tions of the reactants, failed to reproduce the experimental sub-barrier fusion cross-sections. A positive Q-value proton transfer channel exists for both systems. It is observed that coupling to the proton pick-up channel in the coupled-channels calculations is necessary to obtain the sub-barrier fusion cross-sections for both systems. Transfer measurements are performed for 19F + 64,68Zn systems at near-barrier energies. The experimental data show the existence of one proton pick-up channel in both systems. The transfer data is used to extract the transfer probability of the +1p channel. The extracted transfer probabilities of the +1p channel differ for the two systems. The experimental values of the slope parameter of the +1p channels differ in both systems, whereas the corresponding theoretical values are comparable. The transfer measurements point towards a correlation of the +1p channel with the sub-barrier fusion cross-section enhancement observed for the studied systems.