Compton scattering by mesons in nuclei: Experiment on 208Pb☆

Abstract Using 58 and 73 MeV tagged photons and scattering angles from 60° to 150°, it is shown that it is possible to observe Compton scattering by “mesons in nuclei” through an incomplete cancellation of the mesonic (exchange-current) seagull amplitude by parts of the nuclear resonance amplitude related to the giant-dipole resonance of 208 Pb. This phenomenon is a property of an extended nucleus and, therefore, cannot be studied on the deuteron. Predictions of the exchange from factor which determines the angular distribution of the exchange seagull amplitude are compared with experimental data.