Sub-barrier backward quasielastic scattering: A probe of the hexadecapole deformation

The quasielastic scattering excitation functions for O-16 + Sm-152, Er-170 and Yb-174 were measured with high precision at a backward angle with small energy intervals at energies near the Coulomb barriers. The hexadecapole deformation (beta(4)) of the target nuclei was extracted by using the lower-energy data and the obtained values agree with the available results reasonably well. This offers a sensitive method to extract beta(4). This method is especially meaningful for the radioactive nuclei considering the low beam intensities.