Nuclear compton scattering from pion threshold to the delta

Abstract The first measurements of elastic photon scattering on complex nuclei from 150 MeV to the Δ(1232) ( E γ = 300 MeV) are compared with theoretical calculations. Data on 4 He at the Δ peak are in agreement with a Δh calculation, but substantial disagreement occurs at lower energies that is at least partly due to the approximate treatment of non-resonant parts of the elementary nucleon amplitude. An impulse approximation calculation which includes meson exchange provides an adequate description of the data at 187 MeV on 4 He . Improved data on the proton at 20–30° and 120–140° at a range of energies are in agreement with a recent dispersion relation calculation. Data taken on 12 C are still too preliminary to report, due to the difficulty of eliminating inelastic contributions.