Threshold behaviour of effective potential for 6,7Li+58,64Ni around the Coulomb barrier

Abstract

In order to probe the effect of the breakup or transfer induced breakup coupling on the energy dependence of the optical potential in the presence of conventional quasielastic couplings, the elastic scattering angular distributions for of the potential components with decreasing energy were extracted. A further analysis of the measured angular distributions, along with the existing data for 6¤ 7 Li+ 58 Ni, was performed with two different model potentials -one with the folded potential normalized with a complex factor (OMP1) and the other with a hybrid potential composed of a renormalized folded real and a phenomenological imaginary (OMP2) potential components. All the model potentials predict similar energy dependent behaviour for the interaction potential around the barrier indicating a model independence of the observed behaviour. The observed energy dependences of the strengths of the real and imaginary potentials also corroborate with the dispersion relation prediction for both the 6 Li+ 64 Ni and 6 Li+ 58 Ni systems. Though the evidence of breakup is distinct in the energy variation of the potential strengths for 6 Li+ 58¤ 64 Ni systems, close to the barrier the variation is more in the line of conventional threshold anomaly. Also the threshold behaviour of the interaction potential does not indicate any distinct isotopic dependence for 6 Li+ 58¤ 64 Ni. On the other hand, though 7 Li+ 64 Ni shows normal threshold behaviour, for 7 Li+ 58 Ni, the potential does not exhibit any significant energy dependence. Unlike 6 Li, in case of 7 Li a distinct isotopic dependence has been observed for 58 Ni and 64 Ni. 10th Symposium on Nuclei in the Cosmos