Charged particle decay of giant resonances following inelastic alpha scattering at zero degrees

In a coincidence experiment, the authors investigated the decay by charged particles of giant resonances in /sup 24/Mg, /sup 28/Si, /sup 58/Ni, /sup 64/Zn and /sup 92/Mo following inelastic scattering of 129 MeV alpha particles into 00. Due to axial symmetry model independent branching ratios were obtained. The results support previous assumptions on the out-of-plane behaviour of angular correlations. Symmetric α/sub o/ angular correlations were obtained both with and without background subtraction, which demonstrates the expected minor role of quasifree scattering contributions to 00 scattering. Evidence is presented for monopole strength exhausting 4% and 10% of EO-EWSR, respectively, in the α/sub o/ channel alone of /sup 28/Si and /sup 24/Mg. The population of final states in proton decay is similar to that in proton pickup indicating both direct decay of giant resonances and a strongly related structure of ground state and giant resonances. The direct proton decay of the giant quadrupole resonance is particularly surprising for /sup 58/Ni where previous experiments had deduced dominant statistical decay