G{sub E{sub p}}/G{sub M{sub p}} ratio by polarization transfer in e --> p --> ep -->

The ratio of the proton's elastic electromagnetic form factors, G{sub E{sub p}}/G{sub M{sub p}} was obtained by measuring P{sub i} and P{sub l}, the transverse and the longitudinal recoil proton polarization, respectively. For elastic ep to ep, G{sub E{sub p}}/G{sub M{sub p}} is proportional to P{sub t}/P{sub l}. Simultaneous measurement of P{sub t} and P{sub l} in a polarimeter provides good control of the systematic uncertainty. The results for the ratio G{sub E{sub p}}/G{sub M{sub p}} show a systematic decrease as Q{sup 2} increases from 0.5 to 3.5 GeV{sup 2}, indicating for the first time a definite difference in the spatial distribution of charge and magnetization currents in the proton.