The JLab recoil polarization measurements of the proton form factors ratio GEp/GMp

A series of experiments initiated at the then new CEBAF electron accelerator in Newport News Virginia in the late nineties, resulted in unexpected results, changing significantly our understanding of the structure of the proton. These experiments used a relatively new technique to obtain the two form factors of the proton, polarization. An intense beam of highly polarized electrons with energy up to 6 GeV was made to interact with protons in a hydrogen target, and the resulting polarization of the recoiling protons was obtain from a second interaction in a polarimeter. After a short introduction I will introduce the subject of elastic electron scattering, describe some of the apparatus required for such experiments, show results and then give a brief outline of several theoretical considerations to put the results in a proper perspective.