The threshold anomaly in inelastic scattering

New measurements of the elastic scattering of 16O by 208Pb and inelastic scattering to the 208Pb(31-) state have been made at 70, 74, 78, 82 and 94 MeV. These, together with existing data, have been analyzed using a conventional collective model and DWBA formalism. The real and imaginary parts of the transition potential determined in the surface region exhibit a rapid energy variation in the threshold region reminiscent of the threshold anomaly observed in the elastic potential. At several energies above threshold, inelastic distributions could not be adequately reproduced within the confines of the model. These results cast doubt on the adequacy of the collective model to describe this inelastic excitation process in regions of a threshold anomaly. (orig.)