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

New data for the quasielastic scattering of 20Ne from a 28Si target at incident energies of 42.5 MeV and 52.3 MeV and for the 28Si(20Ne, 24Mg)24Mg, 28Si(20Ne, 16O)32S and 28Si(20Ne, 12C)36Ar transfer reactions at 52.3 MeV are reported. Oscillations are observed in the backward angle quasielastic scattering data at 52.3 MeV and the 28Si( 20Ne, 12C)36Ar 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 28Si(20Ne, 12C)36Ar transfer data assuming a sequential α transfer process with α-particle form factors from the literature. The addition of direct 8Be 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 8Be emission thresholds of 20Ne, 28Si and 36Ar, suggesting that the observed structure is of resonance-like origin. An optical model analysis of the quasielastic scattering data is also reported.