Radiative Capture of Intermediate-Energy Protons to High-Lying States in Light Nuclei

Observations are reported from the first systematic studies of proton radiative capture at intermediate energies. In addition to captures to the ground and first few excited states, the reactions /sup 11/B(p,..gamma..)/sup 12/C and /sup 27/Al(p,..gamma..)/sup 28/Si reveal unexpectedly strong transitions to isolated high-lying states. These latter transitions could take place via ''second-harmonic'' giant resonances. Protons on /sup 12/C produce a rich spectrum of ..gamma.. rays which may arise from captures to high-lying single-particle states.