No abstract available

[en] The polarized and tagged Graal gamma-ray beam is obtained by backward Compton scattering of laser light on the high-energy electrons circulating in the ESRF storage ring. This technique, first developed for the Ladon beam on the storage ring Adone at LNF [1], provides gamma-ray beams with linear or circular polarizations close to one and well known. The Graal beam covers the energy region between 600 and 1500 MeV thus allowing the study of baryon resonances up to an energy of 1916 MeV, in large part by precision measurements of beam polarization asymmetries in meson photoproduction on the nucleons.