G(E(p)) / G(M(p)) ratio by polarization transfer in polarized e p ---> e polarized p

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 t} and P{sub l} , the transverse and the longitudinal recoil proton polarization, respectively. For elastic e(vector sign)p{yields}ep(vector sign) , 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. (c) 2000 The American Physical Society.