Nuclear photon scattering by Si

Photon scattering cross sections for four angles, in the energy range between 15 and 100 MeV have been measured. Since the counting rate is pile-up-limited, the use of a c.w. accelerator is essential, in order to eliminate this effect as much as possible. As in previous experiments, the results were analyzed in combination with total nuclear photon-absorption experiments performed some time ago. A consistent picture evolves for a certain set of a small number of lorentzians, describing the absorption cross section. As for carbon, the E2 resonance at 24.5 MeV can be described best by implying a coupled-channel (Fano structure) situation. Inelastic scattering requires only one energy-independent parameters, equal to 0.36, for the ratio of the squared reduced matrix elements between inelastic to elastic scattering. (orig.)