Study of heavy-ion reaction at energy near coulomb-barrier by backward quasi-elastic scattering

Nuclear reactions with heavy-ions at energies near the Coulomb-barrier were studied by the backward quasi-elastic scattering (QEL) method. The QEL excitation functions of ¹⁶O+ ^152,154Sm, ¹⁸⁴W, ¹⁹⁶Pt, and ²⁰⁸Pb were measured with high precision to extract the surface diffuseness parameters of the nuclear potential. It is shown that the surface diffuseness parameters become normal when the coupled-channels (CC) effects are taken into account. Based on the sensitivity of the barrier distribution on nuclear structure, the hexadecapole deformation parameters of target nuclei were tentatively extracted from the backward QEL excitation functions of ¹⁶O+ ¹⁵²Sm, ¹⁷⁰Er, and ¹⁷⁴Yb. The extracted values are consistent with the available tendency, indicating the feasibility of this method. Moreover, the breakup effects of the weakly-bound system of ⁹Be+ ²⁰⁸Pb were studied. Results show that the QEL barrier distribution was shifted to the lower-energy side comparing with the fusion one. Above results further show that the barrier distribution not only contains the information of nuclear structure but also reflects the reaction mechanism. (authors)