Proton elastic form factor ratios to Q{sup 2} = 3.5 GeV{sup 2} by polarization transfer

Journal Article · Sat Jan 01 04:00:00 EST 2005

OSTI ID:837157

Punjabi, V; Perdrisat, C F

The ratio of the proton elastic electromagnetic form factors, G{sub E{sub p}}/G{sub M{sub p}}, was obtained by measuring P{sub t} and P{sub {ell}}, the transverse and longitudinal recoil proton polarization components, respectively, for the elastic {rvec e}p {yields} e{rvec p} reaction in the four-momentum transfer squared range of 0.5 to 3.5 GeV{sup 2}. In the single-photon exchange approximation, the ratio G{sub E{sub p}}/G{sub M{sub p}} is directly proportional to the ratio P{sub t}/P{sub {ell}}. The simultaneous measurement of P{sub t} and P{sub {ell}} in a polarimeter reduces systematic uncertainties. The results for the ratio G{sub E{sub p}}/G{sub M{sub p}} show a systematic decrease with increasing Q{sup 2}, indicating for the first time a definite difference in the distribution of charge and magnetization in the proton. The data have been re-analyzed and systematic uncertainties have become significantly smaller than previously published results.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (US)
• Sponsoring Organization: US Department of Energy; USDOE Office of Energy Research (ER) (US)
• DOE Contract Number: AC05-84ER40150
• OSTI ID: 837157
• Report Number(s): JLAB-PHY-05-292; DOE/ER/40150-3180; nucl-ex/0501018
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
DISTRIBUTION
ELECTROMAGNETIC FORM FACTORS
FORM FACTORS
MAGNETIZATION
POLARIMETERS
POLARIZATION
PROTONS