All the states of the nucleon. Nucleon spectroscopy through the production of mesons

The photoproduction of mesons on the nucleon gives a direct access to its spectroscopy and is a promising way for the study of the structure of the nucleon. The GRAAL experiment uses a tagged and polarized photon beam produced through the Compton diffusion of laser photons on the electrons circulating in the ESRF storage ring. The combination of this photon beam and an efficient detection system has allowed a series of measurements concerning the photoproduction of light mesons on the proton and on the neutron. The first 4 chapters are dedicated to the nucleon spectroscopy: the nucleon models and their consequences on the excited levels are recalled, the experimental technique used is described and the difficulties due to the extraction of relevant data are presented. Highly accurate measurements of cross-sections, Σ asymmetry beams and resonance parameters have been performed. The last part is dedicated to the principle of the measurement of the electric dipole momentum of the neutron. (A.C.)