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Browsing by Author "Gaskell, D."

Now showing 1 - 6 of 6
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    First Determination of the Weak Charge of the Proton
    Androic, D.; Armstrong, D. S.; Asaturyan, A.; Averett, T.; Balewski, J.; Beaufait, J.; Beminiwattha, R. S.; Benesch, J.; Benmokhtar, F.; Birchall, J.; Carlini, R. D.; Cates, G. D.; Cornejo, J. C.; Covrig, S.; Dalton, M. M.; Davis, C. A.; Deconinck, W.; Diefenbach, J.; Dowd, J. F.; Dunne, J. A.; Dutta, D.; Duvall, W. S.; Elaasar, M.; Falk, W. R.; Finn, J. M.; Forest, T.; Gaskell, D.; Gericke, M. T. W.; Grames, J.; Gray, V. M.; Grimm, K.; Guo, F.; Hoskins, J. R.; Johnston, K.; Jones, D.; Jones, M.; Jones, R.; Kargiantoulakis, M.; King, P. M.; Korkmaz, E.; Kowalski, S.; Leacock, John; Leckey, J.; Lee, A. R.; Lee, J. H.; Lee, L.; MacEwan, S.; Mack, D.; Magee, J. A.; Mahurin, R.; Mammei, J.; Martin, J. W.; McHugh, M. J.; Meekins, D.; Mei, J.; Michaels, R.; Micherdzinska, A.; Mkrtchyan, A.; Mkrtchyan, H.; Morgan, N.; Myers, K. E.; Narayan, A.; Ndukum, L. Z.; Nelyubin, V.; Nuruzzaman; van Oers, W. T. H.; Opper, A. K.; Page, S. A.; Pan, J.; Paschke, K. D.; Phillips, S. K.; Pitt, M. L.; Poelker, M.; Rajotte, J. F.; Ramsay, W. D.; Roche, J.; Sawatzky, B.; Seva, T.; Shabestari, M. H.; Silwal, R.; Simicevic, N.; Smith, G. R.; Solvignon, P.; Spayde, D. T.; Subedi, A.; Subedi, R.; Suleiman, R.; Tadevosyan, V.; Tobias, W. A.; Tvaskis, V.; Waidyawansa, B.; Wang, P.; Wells, S. P.; Wood, S. A.; Yang, S.; Young, R. D.; Zhamkochyan, S. (American Physical Society, 2013-10-02)
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    Measurement of the Parity-Violating Asymmetry in Inclusive Electroproduction of pi(-) near the Delta(0) Resonance
    Androic, D.; Armstrong, D. S.; Arvieux, J.; Bailey, S. L.; Beck, D. H.; Beise, E. J.; Benesch, J.; Benmokhtar, F.; Bimbot, L.; Birchall, J.; Bosted, P.; Breuer, H.; Capuano, C. L.; Chao, Y. C.; Coppens, A.; Davis, C. A.; Ellis, C.; Flores, G.; Franklin, G.; Furget, C.; Gaskell, D.; Gericke, M. T. W.; Grames, J.; Guillard, G.; Hansknecht, J.; Horn, T.; Jones, M. K.; King, P. M.; Korsch, W.; Kox, S.; Lee, L.; Liu, J.; Lung, A.; Mammei, J.; Martin, J. W.; McKeown, R. D.; Micherdzinska, A.; Mihovilovic, M.; Mkrtchyan, H.; Muether, M.; Page, S. A.; Papavassiliou, V.; Pate, S. F.; Phillips, S. K.; Pillot, P.; Pitt, M. L.; Poelker, M.; Quinn, B.; Ramsay, W. D.; Real, J. S.; Roche, J.; Roos, P.; Schaub, J.; Seva, T.; Simicevic, N.; Smith, G. R.; Spayde, D. T.; Stutzman, M.; Suleiman, R.; Tadevosyan, V.; van Oers, W. T. H.; Versteegen, M.; Voutier, E.; Vulcan, W.; Wells, S. P.; Williamson, S. E.; Wood, S. A. (American Physical Society, 2012-03-20)
    The parity-violating (PV) asymmetry of inclusive pi(-) production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360 MeV. The physics process dominating pion production for these kinematics is quasifree photoproduction off the neutron via the Delta(0) resonance. In the context of heavy-baryon chiral perturbation theory, this asymmetry is related to a low-energy constant d(Delta)(-) that characterizes the parity-violating gamma N Delta coupling. Zhu et al. calculated d(Delta)(-) in a model benchmarked by the large asymmetries seen in hyperon weak radiative decays, and predicted potentially large asymmetries for this process, ranging from A(gamma)(-) = -5.2 to + 5.2 ppm. The measurement performed in this work leads to A(gamma)(-) = -0.36 +/- 1.06 +/- 0.37 +/- 0.03 ppm (where sources of statistical, systematic and theoretical uncertainties are included), which would disfavor enchancements considered by Zhu et al. proportional to V-ud/V-us. The measurement is part of a program of inelastic scattering measurements that were conducted by the G0 experiment, seeking to determine the N - Delta axial transition form factors using PV electron scattering.
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    Measurement of the Spectral Function of 40Ar through the (e, e'p) reaction
    Ankowski, Artur M.; Beminiwattha, R. S.; Benhar, Omar; Crabb, D. G.; Day, D. B.; Garibaldi, F.; Garvey, G. T.; Gaskell, D.; Giusti, C.; Hansen, O.; Higinbotham, D. W.; Holmes, R.; Jen, C. M.; Jiang, X.; Keller, D.; Keppel, C. E.; Lindgren, R.; Link, Jonathan M.; Liyanage, N.; Mariani, Camillo; Meucci, A.; Mills, G. B.; Myers, L.; Pitt, M. L.; Rondon, O. A.; Sakuda, M.; Sawatzky, B.; Souder, P. A.; Urciuoli, G. M.; Wood, S.; Zhang, J. (2014-07)
    The interpretation of the signals detected by high precision experiments aimed at measuring neutrino oscillations requires an accurate description of the neutrino-nucleus cross sections. One of the key element of the analysis is the treatment of nuclear effects, which is one of the main sources of systematics for accelerator based experiments such as the Long Baseline Neutrino Experiment (LBNE). A considerable effort is currently being made to develop theoretical models capable of providing a fully quantitative description of the neutrino-nucleus cross sections in the kinematical regime relevant to LBNE. The approach based on nuclear many-body theory and the spectral function formalism has proved very successful in explaining the available electron scattering data in a variety of kinematical conditions. The first step towards its application to the analysis of neutrino data is the derivation of the spectral functions of nuclei employed in neutrino detectors, in particular argon. We propose a measurement of the coincidence (e, e'p) cross section on argon. This data will provide the experimental input indispensable to construct the argon spectral function, thus paving the way for a reliable estimate of the neutrino cross sections. In addition, the analysis of the (e, e'p) data will help a number of theoretical developments, like the description of final-state interactions needed to isolate the initial-state contributions to the observed single-particle peaks, that is also needed for the interpretation of the signal detected in neutrino experiments.
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    Strange Quark Contributions to Parity-Violating Asymmetries in the Backward Angle G0 Electron Scattering Experiment
    Androic, D.; Armstrong, D. S.; Arvieux, J.; Bailey, S. L.; Beck, D. H.; Beise, E. J.; Benesch, J.; Benmokhtar, F.; Bimbot, L.; Birchall, J.; Bosted, P.; Breuer, H.; Capuano, C. L.; Chao, Y. C.; Coppens, A.; Davis, C. A.; Ellis, C.; Flores, G.; Franklin, G.; Furget, C.; Gaskell, D.; Gericke, M. I. W.; Grames, J.; Guillard, G.; Hansknecht, J.; Horn, T.; Jones, M.; King, P. M.; Korsch, W.; Kox, S.; Lee, L.; Liu, J.; Lung, A.; Mammei, J.; Martin, J. W.; McKeown, R. D.; Mihovilovic, M.; Micherdzinska, A.; Mkrtchyan, H.; Muether, M.; Page, S. A.; Papavassiliou, V.; Pate, S. F.; Phillips, S. K.; Pillot, P.; Pitt, M. L.; Poelker, M.; Quinn, B.; Ramsay, W. D.; Real, J. S.; Roche, J.; Roos, P.; Schaub, J.; Seva, T.; Simicevic, N.; Smith, G. R.; Spayde, D. T.; Stutzman, M.; Suleiman, R.; Tadevosyan, V.; van Oers, W. T. H.; Versteegen, M.; Voutier, E.; Vulcan, W.; Wells, S. P.; Williamson, S. E.; Wood, S. A.; G0 Collaboration (American Physical Society, 2010-01-08)
    We have measured parity-violating asymmetries in elastic electron-proton and quasielastic electron-deuteron scattering at Q(2) = 0.22 and 0.63 GeV(2). They are sensitive to strange quark contributions to currents in the nucleon and the nucleon axial-vector current. The results indicate strange quark contributions of less than or similar to 10% of the charge and magnetic nucleon form factors at these four-momentum transfers. We also present the first measurement of anapole moment effects in the axial-vector cur-rent at these four-momentum transfers.
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    Transverse Beam Spin Asymmetries at Backward Angles in Elastic Electron-Proton and Quasielastic Electron-Deuteron Scattering
    Androic, D.; Armstrong, D. S.; Arvieux, J.; Bailey, S. L.; Beck, D. H.; Beise, E. J.; Benesch, J.; Benmokhtar, F.; Bimbot, L.; Birchall, J.; Bosted, P.; Breuer, H.; Capuano, C. L.; Chao, Y. C.; Coppens, A.; Davis, C. A.; Ellis, C.; Flores, G.; Franklin, G.; Furget, C.; Gaskell, D.; Gericke, M. T. W.; Grames, J.; Guillard, G.; Hansknecht, J.; Horn, T.; Jones, M. K.; King, P. M.; Korsch, W.; Kox, S.; Lee, L.; Liu, J.; Lung, A.; Mammei, J.; Martin, J. W.; McKeown, R. D.; Micherdzinska, A.; Mihovilovic, M.; Mkrtchyan, H.; Muether, M.; Page, S. A.; Papavassiliou, V.; Pate, S. F.; Phillips, S. K.; Pillot, P.; Pitt, M. L.; Poelker, M.; Quinn, B.; Ramsay, W. D.; Real, J. S.; Roche, J.; Roos, P.; Schaub, J.; Seva, T.; Simicevic, N.; Smith, G. R.; Spayde, D. T.; Stutzman, M.; Suleiman, R.; Tadevosyan, V.; van Oers, W. T. H.; Versteegen, M.; Voutier, E.; Vulcan, W.; Wells, S. P.; Williamson, S. E.; Wood, S. A.; Pasquini, B.; Vanderhaeghen, M.; G0 Collaboration (American Physical Society, 2011-07-05)
    We have measured the beam-normal single-spin asymmetries in elastic scattering of transversely polarized electrons from the proton, and performed the first measurement in quasielastic scattering on the deuteron, at backward angles (lab scattering angle of 108 degrees) for Q(2) = 0.22 GeV2/c(2) and 0.63 GeV2/c(2) at beam energies of 362 and 687 MeV, respectively. The asymmetry arises due to the imaginary part of the interference of the two-photon exchange amplitude with that of single-photon exchange. Results for the proton are consistent with a model calculation which includes inelastic intermediate hadronic (pi N) states. An estimate of the beam-normal single-spin asymmetry for the scattering from the neutron is made using a quasistatic deuterium approximation, and is also in agreement with theory.
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    Transverse beam spin asymmetries in forward-angle elastic electron-proton scattering
    Armstrong, D. S.; Arvieux, J.; Asaturyan, R.; Averett, T.; Bailey, S. L.; Batigne, G.; Beck, D. H.; Beise, E. J.; Benesch, J.; Bimbot, L.; Birchall, J.; Biselli, A.; Bosted, P.; Boukobza, E.; Breuer, H.; Carlini, R.; Carr, Rachel E.; Chant, N.; Chao, Y. C.; Chattopadhyay, S.; Clark, R.; Covrig, S.; Cowley, A.; Dale, D.; Davis, C.; Falk, W.; Finn, J. M.; Forest, T.; Franklin, G.; Furget, C.; Gaskell, D.; Grames, J.; Griffioen, K. A.; Grimm, K.; Guillon, B.; Guler, H.; Hannelius, L.; Hasty, R.; Allen, A. H.; Horn, T.; Johnston, K.; Jones, M.; Kammel, P.; Kazimi, R.; King, P. M.; Kolarkar, A.; Korkmaz, E.; Korsch, W.; Kox, S.; Kuhn, J.; Lachniet, J.; Lee, L.; Lenoble, J.; Liatard, E.; Liu, J.; Loupias, B.; Lung, A.; Marchand, D.; Martin, J. W.; McFarlane, K. W.; McKee, D. W.; McKeown, R. D.; Merchez, F.; Mkrtchyan, H.; Moffit, B.; Morlet, M.; Nakagawa, I.; Nakahara, K.; Neveling, R.; Ong, S.; Page, S.; Papavassiliou, V.; Pate, S. F.; Phillips, S. K.; Pitt, M. L.; Poelker, M.; Porcelli, T. A.; Quemener, G.; Quinn, B.; Ramsay, W. D.; Rauf, A. W.; Real, J. S.; Roche, J.; Roos, P.; Rutledge, G. A.; Secrest, J.; Simicevic, N.; Smith, G. R.; Spayde, D. T.; Stepanyan, S.; Stutzman, M.; Sulkosky, V.; Tadevosyan, V.; Tieulent, R.; de Wiele, J. V.; van Oers, W. T. H.; Voutier, E.; Vulcan, W.; Warren, G.; Wells, S. P.; Williamson, S. E.; Wood, S. A.; Yan, C.; Yun, J.; Zeps, V. (American Physical Society, 2007-08-31)
    We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely polarized 3 GeV electrons from unpolarized protons at Q(2)=0.15, 0.25 (GeV/c)(2). The results are inconsistent with calculations solely using the elastic nucleon intermediate state and generally agree with calculations with significant inelastic hadronic intermediate state contributions. A(n) provides a direct probe of the imaginary component of the 2 gamma exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments.