Charged particle decays from the isoscalar giant quadrupole resonance in 28Si

The charged particle (c) decay from the isoscalar giant quadrupole resonance (GQ0R) in 28Si has been studied in a kinematically complete 28Si(α,α'c) coincidence experiment at Esub(α)=155 MeV. The α'c coincidence spectra show α- as well as p-decay of the GQ0R and indicate that different parts of the GQ0R have strongly different decay branchings into individual decay channels csub(i) leading to low-lying final states. Coincidence spectra with c-particles detected in anti-quasifree kinematics show that quasifree scattering contributions can be minimized. Angular correlations have been obtained for c=p and α decays into low-lying states of 27Al and 24Mg, respectively. For the α0 decay, interference phenomena have been observed in the angular correlations as well as in the fine structure of the α'-α0 coincidence spectra, indicating contributions from fast direct α0 decay. Direct and statistical decay features of the GQ0R region are discussed on the basis of the measured spectra, angular correlations and deduced branching ratios which are compared to Hauser-Feshbach predictions. (orig.)