Scattering of He-6 at energies around the Coulomb barrier

摘要

We have measured elastic cross sections of the scattering of 6 He at E-Lab 14, 16, 17, 18 and 22 MeV on Pb-208 in the angular ranges of 20 degrees-64 degrees and 135 degrees-170 degrees. A significant amount of He-4 events is found at energies well below the Coulomb barrier, that becomes dominant above it. Optical model calculations have been performed including a dynamic polarization potential. Very large imaginary diffuseness parameter is needed in order to describe the experimental distributions.