[en] Precision measurements of the relative analyzing powers of five electron beam polarimeters, based on Compton, Moller, and Mott scattering, have been performed using the CEBAF accelerator at the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory). A Wien filter in the 100 keV beamline of the injector was used to vary the electron spin orientation exiting the injector. High statistical precision measurements of the scattering asymmetry as a function of the spin orientation were made with each polarimeter. Since each polarimeter receives beam with the same magnitude of polarization, these asymmetry measurements permit a high statistical precision comparison of the relative analyzing powers of the five polarimeters. This is the first time a precise comparison of the analyzing powers of Compton, Moller, and Mott scattering polarimeters has been made. Statistically significant disagreements among the values of the beam polarization calculated from the asymmetry measurements made with each polarimeter reveal either errors in the values of the analyzing power, or failure to correctly include all systematic effects. The measurements reported here represent a first step toward understanding the systematic effects of these electron polarimeters. Such studies are necessary to realize high absolute accuracy (ca. 1%) electron polarization measurements, as required for some parity violation measurements planned at Jefferson Laboratory. Finally, a comparison of the value of the spin orientation exiting the injector that provides maximum longitudinal polarization in each experimental hall leads to an independent and very precise (better than 10-4) absolute measurement of the final electron beam energy

[en] The ratio of the proton's electric to magnetic form factor, G_E/G_M, can be extracted in elastic electron-proton scattering by measuring either cross sections, beam-target asymmetry or recoil polarization. Separate determinations of G_E/G_M by cross sections and recoil polarization observables disagree for Q² > 1 (GeV/c)². Measurement by a third technique might uncover an unknown systematic error in either of the previous measurements. The beam-target asymmetry has been measured for elastic electron-proton scattering at Q² = 1.51 (GeV/c)² for target spin orientation aligned perpendicular to the beam momentum direction. This is the largest Q² at which G_E/G_M has been determined by a beam-target asymmetry experiment. The result, μG_E/G_M = 0.884 +/- 0.027 +/- 0.029, is compared to previous world data

[en] We report on precision measurements of the elastic cross section for electron-proton scattering performed in Hall C at Jefferson Lab. The measurements were made at 28 distinct kinematic settings covering a range in momentum transfer of 0.4 < Q2 < 5.5 (GeV/c)2. These measurements represent a significant contribution to the world's cross section data set in the Q2 range, where a large discrepancy currently exists between the ratio of electric to magnetic proton form factors extracted from previous cross section measurements and that recently measured via polarization transfer in Hall A at Jefferson Lab. This data set shows good agreement with previous cross section measurements, indicating that if a heretofore unknown systematic error does exist in the cross section measurements, then it is intrinsic to all such measurements

[en] The RSS collaboration has measured the spin structure functions g₁ and g₂ of the proton at Jefferson Lab using the lab's polarized electron beam, the Hall C HMS spectrometer and the UVa polarized solid target. The asymmetries A_parallel and A_perp were measured at the elastic peak and in the region of the nucleon resonances (1.085 GeV < W < 1.910 GeV) at an average four momentum transfer of Q² = 1.3 GeV². The extracted spin structure functions and their kinematic dependence make a significant contribution in the study of higher-twist effects and polarized duality tests

[en] We report on precision measurements of the elastic cross section for electron-proton scattering performed in Hall C at Jefferson Lab. The measurements were made at 28 unique kinematic settings covering a range in momentum transfer of 0.4 < Q² < 5.5 (/rm GeV/c)². These measurements represent a significant contribution to the world's cross section data set in the Q² range where a large discrepancy currently exists between the ratio of electric to magnetic proton form factors extracted from previous cross section measurements and that recently measured via polarization transfer in Hall A at Jefferson Lab

[en] The structure functions g₁^p and g₁ⁿ have been measured over the range 0.014 < x < 0.9 and 1 < Q² < 40 GeV² using deep-inelastic scattering of 48 GeV longitudinally polarized electrons from polarized protons and deuterons. We find that the Q² dependence of g₁^p (g₁ⁿ) at fixed x is very similar to that of the spin-averaged structure function F₁^p (F₁ⁿ). From a NLO QCD fit to all available data we find Γ₁^p - Γ₁ⁿ = 0.176 ± 0.003 ± 0.007 at Q² = 5 GeV², in agreement with the Bjorken sum rule prediction of 0.182 ± 0.005

[en] New measurements are reported on the deuteron spin structure function g₁^d. These results were obtained from deep inelastic scattering of 48.3 GeV electrons on polarized deuterons in the kinematic range 0.01 < x < 0.9 and 1 < Q² < 40 (GeV/c)². These are the first high dose electron scattering data obtained using lithium deuteride (⁶Li²H) as the target material. Extrapolations of the data were performed to obtain moments of g₁^d, including Γ₁^d, and the net quark polarization Δ Σ

[en] We have measured the spin structure functions g₂^p and g₂^d and the virtual photon asymmetries A₂^p and A₂^d over the kinematic range 0.02 < x < 0.8 and 1.0 < Q² (le) 30(GeV/c)² by scattering 38.8 GeV longitudinally polarized electrons from transversely polarized NH₃ and ⁶LiD targets.The absolute value of A₂ is significantly smaller than the √R positivity limit over the measured range, while g₂ is consistent with the twist-2 Wandzura-Wilczek calculation. We obtain results for the twist-3 reduced matrix elements d₂^p, d₂^d and d₂ⁿ. The Burkhardt-Cottingham sum rule integral (g₂(x)dx) is reported for the range 0.02 (le) x (le) 0.8

[en] We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 < Q² < 5.5 GeV². The data have been used to accurately perform over 170 Rosenbluth-type longitudinal/transverse separations. The precision R σ_L/σ_T data are presented here, along with the first separate values of the inelastic structure functions F₁ and F_L in this regime. The resonance longitudinal component is found to be significant. With the new data, quark-hadron duality is observed above Q² = 1 GeV² in the separated structure functions independently