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Item Strange-Quark Contributions to Parity-Violating Asymmetries in the Forward G0 Electron-Proton Scattering Experiment(American Physical Society, 2005-08-26) 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.; Korsch, W.; Kox, S.; Kuhn, J.; Lachniet, J.; Lee, L.; Lenoble, J.; Liatard, E.; Liu, J.; Loupias, B.; G0 Collaboration; Lung, A.; MacLachlan, G.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.; Nakos, M.; Neveling, R.; Niccolai, S.; 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.; van de Wiele, J.; van Oers, W.; Voutier, E.; G0 Collaboration; Vulcan, W.; Warren, G.; Wells, S.P.; Williamson, S.E.; Wood, S.A.; Yan, C.; Yun, J.; Zeps, V.; Biselli, A.; Bosted, P.; Boukobza, E.; Breuer, H.; Carlini, R.; Carr, R.; 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.; Hawthorne Allen, A.; Horn, T.; Johnston, K.; Jones, M.; Kammel, P.; Kazimi, R.; King, P.M.; Kolarkar, A.; Korkmaz, E.We have measured parity-violating asymmetries in elastic electron-proton scattering over the range of momentum transfers 0.12≤Q2≤1.0 GeV2. These asymmetries, arising from interference of the electromagnetic and neutral weak interactions, are sensitive to strange-quark contributions to the currents of the proton. The measurements were made at Jefferson Laboratory using a toroidal spectrometer to detect the recoiling protons from a liquid hydrogen target. The results indicate nonzero, Q2 dependent, strange-quark contributions and provide new information beyond that obtained in previous experiments.Item Measurement of Tensor Polarization in Elastic Electron-Deuteron Scattering at Large Momentum Transfer(American Physical Society, 2000-05-29) Abbott, D.; Ahmidouch, A.; Anklin, H.; Arvieux, J.; Ball, J.; Beedoe, S.; Beise, E.J.; Bimbot, L.; Boeglin, W.; Breuer, H.; Brindza, P.; Carlini, R.; Chant, N.S.; Danagoulian, S.; Dow, K.; Ducret, J.-E.; Dunne, J.; Ewell, L.; Eyraud, L.; Furget, C.; Garcon, M.; Gilman, R.; Glashausser, C.; Gueye, P.; Gustafsson, K.; Hafidi, K.; Honegger, A.; Jourdan, J.; Kox, S.; Kumbartzki, G.; Lu, L.; Mack, D.; Markowitz, P.; McIntyre, J.; Meekins, D.; Merchez, F.; Mitchell, J.; Mohring, R.; Mtingwa, S.; Mrktchyan, H.; Pitz, D.; Qin, L.; Ransome, R.D.; Real, J.-S.; Roos, P.G.; Rutt, P.; Sawafta, R.; Stepanyan, S.; Tieulent, R.; Tomasi-Gustafsson, E.; Turchinetz, W.; Vansyoc, K.; Volmer, J.; Voutier, E.; Vulcan, W.; Williamson, C.; Wood, S.A.; Yan, C.; Zhao, J.; Zhao, W.; Lung, A.; Jefferson Lab t20 CollaborationTensor polarization observables ( t20, t21, and t22) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7(GeV/c)2. The experiment was performed at the Jefferson Laboratory in Hall C using the electron High Momentum Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new data determine to much larger Q2 the deuteron charge form factors GC and GQ. They are in good agreement with relativistic calculations and disagree with perturbative QCD predictions.Item Precise Measurement of the Deuteron Elastic Structure Function A(Q2)(American Physical Society, 1999-02-15) Abbott, D.; Ahmidouch, A.; Anklin, H.; Arvieux, J.; Ball, J.; Beedoe, S.; Beise, E.J.; Bimbot, L.; Boeglin, W.; Breuer, H.; Carlini, R.; Chant, N.S.; Danagoulian, S.; Dow, K.; Ducret, J.-E.; Dunne, J.; Ent, R.; Ewell, L.; Eyraud, L.; Furget, C.; Garcon, M.; Gilman, R.; Glashausser, C.; Gueye, P.; Gustafsson, K.; Hafidi, K.; Honegger, A.; Jourdan, J.; Kox, S.; Kumbartzki, G.; Lu, L.; Lung, A.; Mack, D.; Markowitz, P.; McIntyre, J.; Meekins, D.; Merchez, F.; Mitchell, J.; Mohring, R.; Mtingwa, S.; Mrktchyan, H.; Pitz, D.; Qin, L.; Ransome, R.; Real, J.-S.; Roos, P.G.; Rutt, P.; Sawafta, R.; Stepanyan, S.; Tieulent, R.; Tomasi-Gustafsson, E.; Turchinetz, W.; Vansyoc, K.; Volmer, J.; Voutier, E.; Vulcan, W.; Williamson, C.; Wood, S.A.; Yan, C.; Zhao, J.; Zhao, W.; The Jefferson Lab t20 CollaborationThe A(Q2) structure function in elastic electron-deuteron scattering was measured at six momentum transfers Q2 between 0.66 and 1.80(GeV/c)2 in Hall C at Jefferson Laboratory. The scattered electrons and recoil deuterons were detected in coincidence, at a fixed deuteron angle of 60.5°. These new precise measurements resolve discrepancies between older sets of data. They put significant constraints on existing models of the deuteron electromagnetic structure, and on the strength of isoscalar meson exchange currents.Item Measurements of Deuteron Photodisintegration up to 4.0 GeV(American Physical Society, 1998-11-23) Bochna, C.; Terburg, B.P.; Abbott, D.J.; Ahmidouch, A.; Armstrong, C.S.; Arrington, J.; Assamagan, K.A.; Baker, O.K.; Barrow, S.P.; Beatty, D.P.; Beck, D.H.; Beedoe, S.Y.; Beise, E.J.; Belz, J.E.; Bosted, P.E.; Brash, E.J.; Breuer, H.; Cadman, R.V.; Cardman, L.; Carlini, R.D.; Cha, J.; Chant, N.S.; Collins, G.; Cothran, C.; Cummings, W.J.; Danagoulian, S.; Duncan, F.A.; Dunne, J.A.; Dutta, D.; Eden, T.; Ent, R.; Filippone, B.W.; Forest, T.A.; Fortune, H.T.; Frolov, V.V.; Gao, H.; Geesaman, D.F.; Gilman, R.; Gueye, P.L.J.; Gustafsson, K.K.; Hansen, J.-O.; Harvey, M.; Hinton, W.; Holt, R.J.; Jackson, H.E.; Keppel, C.E.; Khandaker, M.A.; Kinney, E.R.; Klein, A.; Koltenuk, D.M.; Kumbartzki, G.; Lung, A.F.; Mack, D.J.; Madey, R.; Markwoitz, P.; McFarlane, K.W.; McKeown, R.D.; Meekins, D.G.; Meziani, Z.-E.; Miller, M.A.; Mitchell, J.H.; Mkrtchyan, H.G.; Mohring, R.M.; Napolitano, J.; Nathan, A.M.; Niculescu, G.; Niculescu, I.; O'Neill, T.G.; Owen, B.R.; Pate, S.F.; Potterveld, D.H.; Price, J.W.; Rakness, G.L.; Ransome, R.; Reinhold, J.; Rutt, P.M.; Salgado, C.W.; Savage, G.; Segel, R.; Simicevic, N.; Stoler, P.; Suleiman, R.; Tang, L.; van Westrum, D.; Vulcan, W.F.; Williamson, S.; Witkowski, M.T.; Wood, S.A.; Yan, C.; Zeidman, B.The first measurements of the differential cross section for the d(γ,p)n reaction up to 4.0 GeV were performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson Laboratory. We report the cross sections at the proton center-of-mass angles of 36°, 52°, 69°, and 89°. These results are in reasonable agreement with previous measurements at lower energy. The 89° and 69° data show constituent-counting-rule behavior up to 4.0 GeV photon energy. The 52° and 36° data disagree with the counting-rule behavior. The quantum chromodynamics (QCD) model of nuclear reactions involving reduced amplitudes disagrees with the present data.Item Transverse Beam Spin Asymmetries in Forward-Angle Elastic Electron-Proton Scattering(American Physical Society, 2007-07-31) 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.; 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.; Van de Wiele, J.; 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.; G0 Collaboration; Biselli, A.; Bosted, P.; Boukobza, E.; Breuer, H.; Carlini, R.; Carr, R.; 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.; Hawthorne Allen, A.; 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.; Quéméner, G.; Quinn, B.; Ramsay, W.D.; Rauf, A.W.; Real, J.-S.We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely polarized 3 GeV electrons from unpolarized protons at Q2=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. An provides a direct probe of the imaginary component of the 2γ exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments.Item Determination of the Pion Charge Form Factor at Q2=1.60 and 2.45 (GeV/c)2(American Physical Society, 2006-11-10) Horn, D.T.; Aniol, K.; Arrington, J.; Barret, B.; Beise, E.J.; Blok, H.P.; Boeglin, W.; Brash, E.J.; Breuer, H.; Chang, C.C.; Christy, M.E.; Ent, R.; Gaskell, D.; Gibson, E.; Holt, R.J.; Huber, G.M.; Jin, S.; Jones, M.K.; Keppel, C.E.; Kim, W.; King, P.M.; Kovaltchouk, V.; Liu, J.; Lolos, G.J.; Mack, D.J.; Margaziotis, D.J.; Markowitz, P.; Matsumura, A.; Meekins, D.; Miyoshi, T.; Mkrtchyan, H.; Niculescu, I.; Okayasu, Y.; Pentchev, L.; Perdrisat, C.; Potterveld, D.; Punjabi, V.; Reimer, P.; Reinhold, J.; Roche, J.; Roos, P.G.; Sarty, A.; Smith, G.R.; Tadevosyan, V.; Tang, L.G.; Tvaskis, V.; Vidakovic, S.; Volmer, J.; Vulcan, W.; Warren, G.; Wood, S.A.; Xu, C.; X. Zheng, X.; Jefferson Lab F_{π} CollaborationThe 1H(e,e′π+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (Fπ) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which Fπ is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction.Item Measurement of tensor polarization in elastic electron-deuteron scattering in the momentum-transfer range 3.8≤q≤4.6 fm-1(1991-07) The, I.; Arvieux, J.; Beck, D.H.; Beise, E.J.; Boudard, A.; Cairns, E.B.; Cameron, J.M.; Dodson, G.W.; Dow, K.A.; Farkhondeh, M.; Fielding, H.W.; Flanz, J.B.; Garcon, M.; Goloskie, R.; Hoibraten, S.; Jourdan, J.; Kowalski, S.; Lapointe, C.; McDonald, W.J.; Ni, B.; Pham, L.D.; Redwine, R.P.; Rodning, N.L.; Roy, G.; Schulze, M.E.; Souder, P.A.; Soukup, J.; Turchinetz, W.E.; Williamson, C.F.; Wilson, K.E.; Wood, S.A.; Zeigler, W.The tensor polarization t20 of the recoil deuteron in elastic e-d scattering has been measured for three values of four-momentum transfer, q=3.78, 4.22, and 4.62 fm-1. The data have been used to locate the first node in the charge monopole form factor of the deuteron at q=4.39±0.16 fm-1. The results for t20 are in reasonable agreement with expectations based on the nucleon-meson description of nuclear dynamicsItem Proton propagation in nuclei studied in the A dependence of the (e,e’p) reaction in the quasifree region(1989-08) Geesaman, D.F.; Gilman, R.; Green, M.C.; Holt, R.J.; Schiffer, J.P.; Zeidman, B.; Garino, G.; Saber, M.; Segel, R.E.; Beise, E.J.; Dodson, G.W.; Hoibraten, S.; Pham, L.D.; Redwine, R.P.; Sapp, W.W.; Williamson, C.F.; Wood, S.A.; Chant, N.S.; Roos, P.G.; Silk, J.D.; Deady, M.; Maruyama, X.K.The A dependence of the (e,e’p) reaction in the quasifree region has been measured at an average Q2 of 0.33 (GeV/c)2 for targets of 12C, 27Al, 58Ni, and 181Ta. The outgoing proton kinetic energy was 180±30 MeV. By comparing the ratio of (e,e’p) coincidence to (e,e’) singles yields, average proton transmissions are obtained for each target. The resulting ‘‘mean free path’’ or, more precisely, the attenuation length for protons in the nucleus is significantly longer than expectations based on the free nucleon-nucleon cross section.Item Measurement of 16O(γ,n)15O at medium energies(1989-05) Beise, E.J.; Dodson, G.; Garçon, M.; Høibråten, S.; Maher, C.; Pham, L.D.; Redwine, R.P.; Sapp, W.; Wilson, K.E.; Wood, S.A.; Deady, M.Exclusive differential cross sections for the 16O(γ,n)15O process have been measured for Eγ=150, 200, and 250 MeV and θL=49°, 59°, and 88°. This measurement is the first of its type to be reported for the energy region above the pion production threshold. An uncollimated bremsstrahlung beam was incident on an H2O target, and neutrons were measured with a recoil proton spectrometer with resolution sufficient to identify the residual 15O ground state. The results are compared to (γ,p) data and to calculations including effects from meson exchange currents.Item Charged pion form factor between Q2=0.60 and 2.45 GeV2. II. Determination of, and results for, the pion form factor(2008-10) Huber, G.M.; Blok, H.P.; Horn, T.; Beise, E.J.; Gaskell, D.; Mack, D.J.; Tadevosyan, V.; Volmer, J.; Abbott, D.; Aniol, K.; Anklin, H.; Armstrong, C.; Arrington, J.; Assamagan, K.; Avery, S.; Baker, O.K.; Barrett, B.; Bochna, C.; Boeglin, W.; Brash, E.J.; Breuer, H.; Chang, C.C.; Chant, N.; Christy, M.E.; Dunne, J.; Eden, T.; Ent, R.; Fenker, H.; Gibson, E.F.; Gilman, R.; Gustafsson, K.; Hinton, W.; Holt, J.; Jackson, H.; Jin, S.; Jones, M.K.; Keppel, C.E.; Kim, P.H.; Kim, W.; King, P.M.; Klein, A.; Koltenuk, D.; Kovaltchouk, V.; Liang, M.; Liu, J.; Lolos, G.J.; Lung, A.; Margaziotis, D.J.; Markowitz, P.; Matsumura, A.; McKee, D.; Meekins, D.; Mitchell, J.; Miyoshi, T.; Mkrtchyan, H.; Mueller, B.; Niculescu, G.; Niculescu, I.; Okayasu, Y.; Pentchev, L.; Perdrisat, C.; Pitz, D.; Potterveld, D.; Punjabi, V.; Qin, L.M.; Reimer, P.E.; Reinhold, J.; Roche, J.; Roos, P.G.; Sarty, A.; Shin, I.K.; Smith, G.R.; Stepanyan, S.; Tang, L.G.; Tvaskis, V.; van der Meer, R.L.J.; Vansyoc, K.; VanWestrum, D.; Vidakovic, S.; Vulcan, W.; Warren, G.; Wood, S.A.; Xu, C.; Yan, C.; Zhao, W.-X.; Zheng, X.; Zihlmann, B.; The Jefferson Lab Fπ CollaborationThe charged pion form factor, Fπ(Q2), is an important quantity that can be used to advance our knowledge of hadronic structure. However, the extraction of Fπ from data requires a model of the 1H(e,e'π+)n reaction and thus is inherently model dependent. Therefore, a detailed description of the extraction of the charged pion form factor from electroproduction data obtained recently at Jefferson Lab is presented, with particular focus given to the dominant uncertainties in this procedure. Results for Fπ are presented for Q2=0.60-2.45 GeV2. Above Q2=1.5 GeV2, the Fπ values are systematically below the monopole parametrization that describes the low Q2 data used to determine the pion charge radius. The pion form factor can be calculated in a wide variety of theoretical approaches, and the experimental results are compared to a number of calculations. This comparison is helpful in understanding the role of soft versus hard contributions to hadronic structure in the intermediate Q2 regime.