G. Testa

New Measurements of High-Momentum Nucleons and Short-Range Structures in Nuclei

We present new measurements of electron scattering from high-momentum nucleons in nuclei. These data allow an improved determination of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data also include the kinematic region where three-nucleon correlations are expected to dominate.

The neutron charge form factor and target analyzing powers from 3He(e→,e′n) scattering

The charge form factor of the neutron has been determined from asymmetries measured in quasi-elastic 3 (He) over right arrow((e) over right arrow, e`n) at a momentum transfer of 0.67 (GeV/c)(2). In addition, the target analyzing power, A(y)(0), has been measured to study effects of final state interactions and meson exchange currents.

Proton G_E/G_M from beam-target asymmetry

The ratio of the protons electric to magnetic form factor, G{sub E}/G{sub M}, can be extracted in elastic electron-proton scattering by measuring cross sections, beam-target asymmetry, or recoil polarization. Separate determinations of G{sub E}/G{sub M} by cross sections and recoil polarization observables disagree for Q{sup 2}>1 (GeV/c){sup 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 Q{sup 2} = 1.51 (GeV/c){sup 2} for target spin orientation aligned perpendicular to the beam momentum direction. This is the largest Q{sup 2} at which G{sub E}/G{sub M} has been determined by a beam-target asymmetry experiment. The result, {mu}G{sub E}/G{sub M}=0.884{+-}0.027{+-}0.029, is compared to previous world data.

Proton Spin Structure in the Resonance Region

We have examined the spin structure of the proton 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. Using the Jefferson Lab polarized electron beam, a spectrometer, and a polarized solid target, we measured the asymmetries A|| and A(perpendicular) to high precision, and extracted the asymmetries A1 and A2, and the spin structure functions g1 and g2. We found a notably nonzero A(perpendicular), significant contributions from higher-twist effects, and only weak support for polarized quark-hadron duality.

Probing Quark-Gluon Interactions with Transverse Polarized Scattering

We have extracted QCD matrix elements from our data on doubly polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element d˜2, which arises strictly from quark-gluon interactions, to be unambiguously nonzero. The data also reveal an isospin dependence of higher twist effects if we assume that the Burkhardt-Cottingham sum rule is valid. The fundamental Bjorken sum rule obtained from the a0 matrix element is satisfied at our low momentum transfer.

Vector and tensor analyzing powers of theH1(d→,γ)He3capture reaction

Precise measurements of the deuteron vector analyzing power A(y)(d) and the tensor analyzing power A(yy) of the H-1(d(-<),gamma)He-3 capture reaction have been performed at deuteron energies of 29 MeV and 45 MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction.Precise measurements of the deuteron vector analyzing power A{sub y}{sup d} and the tensor analyzing power A{sub yy} of the {sup 1}H (d(vector sign),{gamma}){sup 3}He capture reaction have been performed at deuteron energies of 29 MeV and 45 MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction.

Vector and tensor analyzing powers of the ¹H (d⃗,γ)³He capture reaction

Precise measurements of the deuteron vector analyzing power A(y)(d) and the tensor analyzing power A(yy) of the H-1(d(-<),gamma)He-3 capture reaction have been performed at deuteron energies of 29 MeV and 45 MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction.Precise measurements of the deuteron vector analyzing power A{sub y}{sup d} and the tensor analyzing power A{sub yy} of the {sup 1}H (d(vector sign),{gamma}){sup 3}He capture reaction have been performed at deuteron energies of 29 MeV and 45 MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction.

Vector and tensor analyzing powers of the {sup 1}H (d(vector sign),{gamma}){sup 3}He capture reaction

Precise measurements of the deuteron vector analyzing power A(y)(d) and the tensor analyzing power A(yy) of the H-1(d(-<),gamma)He-3 capture reaction have been performed at deuteron energies of 29 MeV and 45 MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction.Precise measurements of the deuteron vector analyzing power A{sub y}{sup d} and the tensor analyzing power A{sub yy} of the {sup 1}H (d(vector sign),{gamma}){sup 3}He capture reaction have been performed at deuteron energies of 29 MeV and 45 MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction.

Vector and Tensor Analyzing Powers of the H(d,gamma)He-3 capture reaction

Precise measurements of the deuteron vector analyzing power A(y)(d) and the tensor analyzing power A(yy) of the H-1(d(-<),gamma)He-3 capture reaction have been performed at deuteron energies of 29 MeV and 45 MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction.Precise measurements of the deuteron vector analyzing power A{sub y}{sup d} and the tensor analyzing power A{sub yy} of the {sup 1}H (d(vector sign),{gamma}){sup 3}He capture reaction have been performed at deuteron energies of 29 MeV and 45 MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction.

Vector and tensor analyzing powers of the H-1 (polarized-d, gamma) He-3-capture reaction

Precise measurements of the deuteron vector analyzing power A(y)(d) and the tensor analyzing power A(yy) of the H-1(d(-<),gamma)He-3 capture reaction have been performed at deuteron energies of 29 MeV and 45 MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction.Precise measurements of the deuteron vector analyzing power A{sub y}{sup d} and the tensor analyzing power A{sub yy} of the {sup 1}H (d(vector sign),{gamma}){sup 3}He capture reaction have been performed at deuteron energies of 29 MeV and 45 MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction.