Fine Structure of Giant Resonance in the28Si(γ, abs) Reaction

The photo-absorption cross section for 28Si has been measured in the energy range 17.5–21.5 MeV, using a high- resolution high-energy photon spectrometer and laser Compton photons. Four intermediate structure peaks in the giant dipole resonance of 28Si have been resolved into about thirty fine-structure peaks. The comparison of the observed structure with those in (γ, p 0) and (γ, n 0) reactions shows that the energies of the fine structure peaks in (γ, abs) reaction have a correlation with those in both of the (γ, p 0) and (γ, n 0) reactions.