BACKWARD ANGLE STRUCTURE IN THE 20 Ne +28 Si QUASIELASTIC SCATTERING

New data for the quasielastic scattering of 20 Ne from a 28 Si target at incident energies of 42.5 MeV and 52.3 MeV and for the 28 Si (20 Ne , 24 Mg )24 Mg , 28 Si (20 Ne , 16 O )32S and 28 Si (20 Ne , 12 C )36 Ar transfer reactions at 52.3 MeV are reported. Oscillations are observed in the backward angle quasielastic scattering data at 52.3 MeV and the 28 Si (20 Ne , 12 C )36 Ar transfer cross-sections are of the same magnitude as those for single-α stripping. Coupled reaction channels (CRC) calculations are unable to describe either the quasielastic or the 28 Si (20 Ne , 12 C )36 Ar transfer data assuming a sequential α transfer process with α-particle form factors from the literature. The addition of direct 8 Be cluster transfer can provide a reasonable description of both data sets, but only with much larger spectroscopic factors than suggested by simple structure calculations or the large 8 Be emission thresholds of 20 Ne , 28 Si and 36 Ar , suggesting that the observed structure is of resonance-like origin. An optical model analysis of the quasielastic scattering data is also reported.