Study of the elastic scattering of 6 He on 208 Pb at energies around the Coulomb barrier

The elastic scattering of 6 He on 208 Pb has been measured at laboratory energies of 14, 16, 18 and 22 MeV. These data were analyzed using phenomenological WoodsSaxon form factors and optical model calculations. A semiclassical polarization potential was used to study the eect of the Coulomb dipole polarizability. Evidence for long range absorption, partially arising from Coulomb dipole polarizability, is reported. The energy variation of the optical potential was found to be consistent with the dispersion relations which connect the real and imaginary parts of the potential.