We have measured the spin-dependent transverse asymmetry, A_T', in quasi-elastic inclusive electron scattering from polarized 3He with high precision at Q^2 = 0.1 to 0.6 (GeV/c)^2. The neutron magnetic form factor, GMn, was extracted at Q^2 = 0.1 and 0.2 (GeV/c)^2 using a non-relativistic Faddeev calculation that includes both final-state interactions (FSI) and meson-exchange currents (MEC). In addition, GMn was extracted at Q^2 = 0.3 to 0.6 (GeV/c)^2 using a Plane Wave Impulse Approximation calculation. The accuracy of the modeling of FSI and MEC effects was tested and confirmed with a precision measurement of the spin-dependent asymmetry in the breakup threshold region of the 3He(pol)(e(pol),e') reaction. The total relative uncertainty of the extracted GMn data is approximately 3%. Close agreement was found with other recent high-precision GMn data in this Q^2 range.

K.G. Fissum, 2, ∗ M. Liang, B.D. Anderson, K.A. Aniol, L. Auerbach, F.T. Baker, J. Berthot, W. Bertozzi, P.-Y. Bertin, L. Bimbot, W.U. Boeglin, E.J. Brash, V. Breton, H. Breuer, E. Burtin, J.R. Calarco, L.S. Cardman, G.D. Cates, 16 C. Cavata, C.C. Chang, J.-P. Chen, E. Cisbani, D.S. Dale, C.W. de Jager, R. De Leo, A. Deur, 16, 3 B. Diederich, P. Djawotho, J. Domingo, J.-E. Ducret, M.B. Epstein, L.A. Ewell, J.M. Finn, H. Fonvieille, B. Frois, S. Frullani, J. Gao, 23 F. Garibaldi, A. Gasparian, 24 S. Gilad, R. Gilman, 25 A. Glamazdin, C. Glashausser, J. Gomez, V. Gorbenko, T. Gorringe, F.W. Hersman, R. Holmes, M. Holtrop, N. d’Hose, C. Howell, G.M. Huber, C.E. Hyde-Wright, M. Iodice, 29 S. Jaminion, M.K. Jones, 3 K. Joo, † C. Jutier, 20 W. Kahl, S. Kato, J.J. Kelly, S. Kerhoas, M. Khandaker, M. Khayat, K. Kino, W. Korsch, L. Kramer, K.S. Kumar, 33 G. Kumbartzki, G. Laveissière, A. Leone, J.J. LeRose, L. Levchuk, R.A. Lindgren, N. Liyanage, 3, 16 G.J. Lolos, R.W. Lourie, 36 R. Madey, 3, 24 K. Maeda, S. Malov, D.M. Manley, D.J. Margaziotis, P. Markowitz, J. Martino, J.S. McCarthy, K. McCormick, 4, 25 J. McIntyre, R.L.J. van der Meer, 3 Z.-E. Meziani, R. Michaels, J. Mougey, S. Nanda, D. Neyret, E.A.J.M. Offermann, 36 Z. Papandreou, C.F. Perdrisat, R. Perrino, G.G. Petratos, S. Platchkov, R. Pomatsalyuk, D.L. Prout, V.A. Punjabi, T. Pussieux, G. Quéméner, 8, 37 R.D. Ransome, O. Ravel, Y. Roblin, 3 R. Roche, 20 D. Rowntree, G.A. Rutledge, ‡ P.M. Rutt, A. Saha, T. Saito, A.J. Sarty, 39 A. Serdarevic-Offermann, 3 T.P. Smith, A. Soldi, P. Sorokin, P. Souder, R. Suleiman, 1 J.A. Templon, § T. Terasawa, L. Todor, ¶ H. Tsubota, H. Ueno, P.E. Ulmer, G.M. Urciuoli, P. Vernin, S. van Verst, B. Vlahovic, 3 H. Voskanyan, J.W. Watson, L.B. Weinstein, K. Wijesooriya, 42, 28 B. Wojtsekhowski, D.G. Zainea, V. Zeps, J. Zhao, and Z.-L. Zhou

As a part of the spin-physics program at the Jefferson Laboratory (TJNAF), a Moller polarimeter has been developed to measure the polarization of electron beam of energies between 0.8 and 6.0 GeV. A unique design of this polarimeter was developed using a set of three quadrupole magnets that provide an angular selection of the Moller electron pairs, a dipole magnet for their energy analysis, an a rotatable target system. The test procedure and commissioning of the polarimeter are presented. The results of beam polarization measurements in long-term physical experiments, the correlation for the three-beam accelerator mode and other effects are discussed.

We have measured the transverse asymmetry from inclusive scattering of longitudinally polarized electrons from polarized {sup 3}He nuclei at quasi-elastic kinematics in Hall A at Jefferson Lab with high statistical and systematic precision. The neutron magnetic form factor was extracted based on Faddeev calculations with an experimental uncertainty of less than 2%.

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.

We have measured the transverse asymmetry A(T') in 3He(e,e(')) quasielastic scattering in Hall A at Jefferson Laboratory with high precision for Q2 values from 0.1 to 0.6 (GeV/c)(2). The neutron magnetic form factor G(n)(M) was extracted based on Faddeev calculations for Q2 = 0.1 and 0.2 (GeV/c)(2) with an experimental uncertainty of less than 2%.

The first (e,e'p) polarization transfer measurements on a nucleus heavier than deuterium have been carried out at Jefferson Laboratory. Transverse and longitudinal components of the polarization of protons ejected in the reaction 16O(e,e'p) were measured in quasielastic perpendicular kinematics at a Q^2 of 0.8 (GeV/c)^2. The data are in good agreement with state of the art calculations, but do not exclude possible changes in the ratio of the electric to magnetic form factors of the nucleon in the nuclear medium at the level of recent theoretical predictions.

As part of the spin physics program at Jefferson Laboratory (JLab), a Møller polarimeter was developed to measure the polarization of electron beam of energies 0.8 to 5.0 GeV. A unique signature for Møller scattering is obtained using a series of three quadrupole magnets which provide an angular selection, and a dipole magnet for energy analysis. The design, commissioning, and the first results of the polarization measurements of this polarimeter will be presented as well as future plans to use its small scattering angle capabilities to investigate physics in the very low Q^2 regime.