We report the measurement of the beam-vector and tensor asymmetries A_{ed}^{V} and A_{d}^{T} in quasielastic (e[over →],e^{'}p) electrodisintegration of the deuteron at the MIT-Bates Linear Accelerator Center up to missing momentum of 500  MeV/c. Data were collected simultaneously over a momentum transfer range 0.1<Q^{2}<0.5  (GeV/c)^{2} with the Bates Large Acceptance Spectrometer Toroid using an internal deuterium gas target polarized sequentially in both vector and tensor states. The data are compared with calculations. The beam-vector asymmetry A_{ed}^{V} is found to be directly sensitive to the D-wave component of the deuteron and has a zero crossing at a missing momentum of about 320  MeV/c, as predicted. The tensor asymmetry A_{d}^{T} at large missing momentum is found to be dominated by the influence of the tensor force in the neutron-proton final-state interaction. The new data provide a strong constraint on theoretical models.

We report a precision measurement of the deuteron tensor analyzing powers T(20) and T(21) at the MIT-Bates Linear Accelerator Center. Data were collected simultaneously over a momentum transfer range Q=2.15-4.50 fm(-1) with the Bates Large Acceptance Spectrometer Toroid using a highly polarized deuterium internal gas target. The data are in excellent agreement with calculations in a framework of effective field theory. The deuteron charge monopole and quadrupole form factors G(C) and G(Q) were separated with improved precision, and the location of the first node of G(C) was confirmed at Q=4.19±0.05 fm(-1). The new data provide a strong constraint on theoretical models in a momentum transfer range covering the minimum of T(20) and the first node of G(C).

The roles played by mesons in the electromagnetic form factors of the nucleon are explored using as a basis a model containing vector mesons with coupling to the continuum together with the asymptotic Q(2) behavior of perturbative QCD. Specifically, the vector dominance model (GKex) developed by E. L. Lomon is employed, as it is known to be very successful in representing the existing high-quality data published to date. An analysis is made of the experimental uncertainties present when the differences between the GKex model and the data are expanded in orthonormal basis functions. A main motivation for the present study is to provide insight into how the various ingredients in this model yield the measured behavior, including discussions of when dipole form factors are to be expected or not, of which mesons are the major contributors, for instance, at low Q(2) or large distances, and of what effects are predicted from coupling to the continuum. Such insights are first discussed in momentum space, followed by an analysis of how different and potentially useful information emerges when both the experimental and theoretical electric form factors are Fourier transformed to coordinate space. While these Fourier transforms should not be interpreted as "charge distributions," nevertheless the roles played by the various mesons, especially those which are dominant at large or small distance scales, can be explored via such experiment-theory comparisons.

The Bates large acceptance spectrometer toroid (BLAST) experiment was operated at the MIT-Bates Linear Accelerator Center from 2003 until 2005. The detector and experimental program were designed to study, in a systematic manner, the spin-dependent electromagnetic interaction in few-nucleon systems. As such the data will provide improved measurements for neutron, proton, and deuteron form factors. The data will also allow details of the reaction mechanism, such as the role of final state interactions, pion production, and resonances to be studied. The experiment used: a longitudinally polarized electron beam stored in the South Hall Storage Ring; a highly polarized, isotopically pure, internal gas target of hydrogen or deuterium provided by an atomic beam source: and a symmetric, general purpose detector based on a toroidal spectrometer with tracking. time-of-flight, Cherenkov, and neutron detectors. Details of the experiment and operation are presented. (C) 2009 Elsevier B.V. All rights reserved.

We report new measurements of the neutron charge form factor at low momentum transfer using quasielastic electrodisintegration of the deuteron. Longitudinally polarized electrons at an energy of 850 MeV were scattered from an isotopically pure, highly polarized deuterium gas target. The scattered electrons and coincident neutrons were measured by the Bates Large Acceptance Spectrometer Toroid (BLAST) detector. The neutron form factor ratio G E n/G M n was extracted from the beam-target vector asymmetry A ed V at four-momentum transfers Q 2= 0.14, 0.20, 0.29, and 0.42 (GeV/c) 2.

We report new measurements of the neutron charge form factor at low momentum transfer using quasielastic electrodisintegration of the deuteron. Longitudinally polarized electrons at an energy of 850 MeV were scattered from an isotopically pure, highly polarized deuterium gas target. The scattered electrons and coincident neutrons were measured by the Bates Large Acceptance Spectrometer Toroid (BLAST) detector. The neutron form factor ratio G(E)(n)/G(M)(n) was extracted from the beam-target vector asymmetry A(ed)(V) at four-momentum transfers Q(2) = 0.14, 0.20, 0.29, and 0.42 (GeV/c)(2).

We report new measurements of the neutron charge form factor at low momentum transfer using quasielastic electrodisintegration of the deuteron. Longitudinally polarized electrons at an energy of 850 MeV were scattered from an isotopically pure, highly polarized deuterium gas target. The scattered electrons and coincident neutrons were measured by the Bates Large Acceptance Spectrometer Toroid (BLAST) detector. The neutron form factor ratio GEn/GMn was extracted from the beam-target vector asymmetry AedV at four-momentum transfers Q2=0.14, 0.20, 0.29, and 0.42 (GeV/c)2.

We report the first precision measurement of the proton electric to magnetic form factor ratio from spin-dependent elastic scattering of longitudinally polarized electrons from a polarized hydrogen internal gas target. The measurement was performed at the MIT-Bates South Hall Ring over a range of four-momentum transfer squared Q2 from 0.15 to 0.65 (GeV/c)(2). Significantly improved results on the proton electric and magnetic form factors are obtained in combination with existing cross-section data on elastic electron-proton scattering in the same Q2 region.

We report the first precision measurement of the proton electric to magnetic form factor ratio from spin-dependent elastic scattering of longitudinally polarized electrons from a polarized hydrogen internal gas target. The measurement was performed at the MIT-Bates South Hall Ring over a range of four-momentum transfer squared Q 2 from 0.15 to 0.65 (GeV/c) 2. Significantly improved results on the proton electric and magnetic form factors are obtained in combination with existing cross-section data on elastic electron-proton scattering in the same Q 2 region.

C. Crawford,1, 2 A. Sindile,3 T. Akdogan,1, 2 R. Alarcon,4 J. Althouse,5 W. Bertozzi,1, 2 E. Booth,6 T. Botto,1, 2 H.J. Bulten,7 J. Calarco,3 B. Clasie,1, 2 C. D’Andrea,5 A. deGrush,1, 2 K. Dow,1, 2 D. Dutta,8 M. Farkhondeh,1, 2 O. Filoti,3 W. Franklin,1, 2 H. Gao,1, 2, 8 E. Geis,4 S. Gilad,1, 2 A. Goodhue,5 W. Haeberli,9 D. Hasell,1, 2 W. Hersman,3 M. Holtrop,3 E. Ilhoff,1, 2 P. Karpius,3 J. Kelsey,1, 2 M. Kohl,1, 2 H. Kolster,1, 2 S. Krause,1, 2 T. Lee,3 A. Maschinot,1, 2 J. Matthews,1, 2 K. McIlhany,10 N. Meitanis,1, 2 R. Milner,1, 2 A. Mosser,10 J. Pavel,5 H.R. Poolman,7 J. Prince,4 J. Rapaport,11 R.P. Redwine,1, 2 J. Seely,1, 2 A. Shinozaki,1, 2 S. Širca,1, 2 T. Smith,5 S. Sobczynski,1, 2 B. Tonguc,4 C. Tschalaer,1, 2 E. Tsentalovich,1, 2 W. Turchinetz,1, 2 J.F.J. van den Brand,7 J. van der Laan,1, 2 T. Wise,9 Y. Xiao,1, 2 W. Xu,8 C. Zhang,1, 2 Z. Zhou,1, 2 V. Ziskin,1, 2 and T. Zwart1, 2 Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA 02139 MIT-Bates Linear Accelerator Laboratory, Middleton, MA 01949 University of New Hampshire, Durham, NH 03824 Arizona State University, Tempe, AZ 85287 Dartmouth College, Hanover, NH 03755 Boston University, Boston, MA 02215 Vrije Universitaet and NIKHEF, Amsterdam, The Netherlands Duke University, Durham, NC 27708-0305 University of Wisconsin, Madison, WI 53706 United States Naval Academy, Annapolis, MD 21402 Ohio University, Athens, OH 45701 (Dated: December 28, 2005)

P. Karpius, J. R. Calarco, T. Akdogan, R. Alarcon, J. Althouse, H. Arenhövel, A. Bernstein, W.Bertozzi, T. Botto, H. J. Bultren, M. Chtangeev, B. Clasie, C. Crawford, C. D’Andrea, A. deGrush, T.W. Donnelly, K. Dow, D. Dutta, M. Farkhondeh, R. Fatemi, O. Filoti, W. Franklin, H. Gao, E. Geis, S. Gilad, A. Goodhue, W. Haeberli, D. Hasell, F. W. Hersman, M. Holtrop, E. Ihloff, J. Kelsey, M. Kohl, H. Kolster, T. Lee, A. Maschinot, J. Matthews, K. McIlhany, A. Mosser, N. Meitanis, R. Milner, J. Pavel, H. R. Poolman, J. Prince, J. Rapaport, R. Redwine, J. Seely, A. Shinozaki, A. Sindile, S. Sirca, T. Smith, S. Sobczynski, B. Tonguc, C. Tschalar, E. Tsentalovich, W. Turchinetz, J. van den Brand, T. Wise, Y. Xiao, W. Xu, A. Young, C. Zhang, Z. Zhou, V. Ziskin, T. Zwart 1. Arizona State University, Tempe AZ 85287 2. Dartmouth College, Hanover, NH 03755 3. Duke University, Durham, NC 27708 4. Johannes Gutenberg-Universität, Mainz, Germany 55099 5. Massachusetts Institute of Technology, Cambridge, MA 02139 and Bates Linear Accelerator Center, Middleton, MA 01949 6. University of New Hampshire, Durham, NH 03824 7. Ohio University, Athens, Ohio 45701 8. United States Naval Academy, Annapolis, MD 21402 9. Vrije Universitaet and NIKHEF, Amsterdam, The Netherlands 1081 10 University of Wisconsin, Madison, WI 53706 (Dated: November 28, 2005)