We measured protons and alpha particles emitted from the giant electric dipole resonance of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ using tagged photons; discrete final states in the residual nuclei were resolved. The proton decay was found to be dominated by the ground state branch. Comparisons with Hauser-Feshbach calculations and spectroscopic factors from nucleon pickup reactions indicate that most proton decay channels have a significant, nonstatistical component. The alpha decay channels appear to be statistical.

NUCLEAR REACTIONS ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}(\gamma , p){}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}(\gamma , \alpha ){}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, $E_{\gamma }=15.6-22.5\mathrm{}$ MeV, $\delta E_{\gamma }=150-200\mathrm{}$ keV; measured partial cross sections.

• Received 2 September 1982

DOI:https://doi.org/10.1103/PhysRevC.27.470