Systematic study of the surface diffuseness of nuclear potential with high precision large-angle quasi-elastic scattering

The excitation functions of quasi-elastic scattering at a backward angle have been measured for the systems of ¹⁶O + ²⁰⁸Pb, ¹⁹⁶Pt, ¹⁸⁴W, and ^154,152Sm at energies well below the Coulomb barrier. The surface diffuseness parameters of the nuclear potentials have been extracted from both single-channel and coupled-channels calculations. Considering the coupling effects, the extracted diffuseness parameters are a = 0.64 - 0.69 fm, which are close to the values extracted from the systematic analysis of elastic and inelastic scattering data. On the other hand, single-channel calculations give somewhat larger values in the range from 0.68 to 0.77 fm, especially for systems with deformed targets.