Physics
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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 Coherent π0 photoproduction on the deuteron up to 4 GeV(1999-09) Meekins, D.G.; 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.; Bochna, C.; 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.; Markowitz, P.; McFarlane, K.W.; McKeown, R.D.; 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, D.; Reinhold, J.; Rutt, P.M; Salgado, C.W.; Savage, G.; Segel, R.E.; Simicevic, N.; Stoler, P.; Suleiman, R.; Tang, L.; Terburg, B.P.; van Westrum, D.; Vulcan, W.F.; Williamson, S.E.; Witkowski, M.T.; Wood, S.A.; Yan, C.; Zeidman, B.The differential cross section for 2H(γ,d)π0 has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions.Item Tensor polarization in elastic electron-deuteron scattering in the momentum transfer range 3.8≤Q≤4.6 fm-1(1994-05) Garçon, M.; 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.; Goloskie, R.; Hoibraten, S.; Jourdan, J.; Kowlaski, 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.; The, I.; Turchinetz, W.E.; Williamson, C.F.; Wilson, K.E.; Wood, S.A.; Zeigler, W.The tensor polarization of the recoil deuteron in elastic electron-deuteron scattering has been measured at the Bates Linear Accelerator Center at three values of four-momentum transfer Q=3.78, 4.22, and 4.62 fm-1, corresponding to incident electron energies of 653, 755, and 853 MeV. The scattered electrons and the recoil deuterons were detected in coincidence. The recoil deuterons were transported to a liquid hydrogen target to undergo a second scattering. The angular distribution of the d→-p scattering was measured using a polarimeter. The polarimeter was calibrated in an auxiliary experiment using a polarized deuteron beam at the Laboratoire National Saturne. A Monte Carlo procedure was used to generate interpolated calibration data because the energy spread in the deuteron energies in the Bates experiment spanned the range of deuteron energies in the calibration experiment. The extracted values of t20 are compared to predictions of different theoretical models of the electromagnetic form factors of the deuteron: nonrelativistic and relativistic nucleon-meson dynamics, Skyrme model, quark models, and perturbative quantum chromodynamics. Along with the world data the structure functions A(Q) and B(Q) are used to separate the charge monopole and charge quadrupole form factors of the deuteron. A node in the charge monopole form factor is observed at Q=4.39±0.16 fm-1.Item Strange Quark Contributions to Parity-Violating Asymmetries in the Forward G0 Electron-Proton Scattering Experiment(2010-01) 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.; 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.; 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.; 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.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 JLab using a toroidal spectrom- eter to detect the recoiling protons from a liquid hydrogen target. The results indicate non-zero, Q2 dependent, strange quark contributions and provide new information beyond that obtained in previous experiments.Item The Strange Quark Contribution to the Proton’s Magnetic Moment(2004-03) Spayde, D.T.; Averett, T.; Barkhuff, D.; Beck, D.H.; Beise, E.J.; Breuer, H.; Carr, R.; Covrig, S.; Dodson, G.; Dow, K.; Farkhondeh, M.; Filippone, B.W.; Franklin, W.; Hasty, R.; Ito, T.M.; Korsch, W.; Kowalski, S.; McKeown, R.D.; Mueller, B.; Pitt, M.L.; Ramsey-Musolf, M.J.; Ritter, J.; Tieulent, R.; Tsentalovich, E.; Wells, S.P.; Yang, B.; Zwart, T.We report a new determination of the strange quark contribution to the proton’s magnetic form factor at a four-momentum transfer Q2 = 0.1(GeV/c)2 from parity-violating e-p elastic scattering. The result uses a revised analysis of data from the SAMPLE experiment which was carried out at the MIT-Bates Laboratory. The data are combined with a calculation of the proton’s axial form factor GeA to determine the strange form factor GsM (Q2=0.1)=0.37±0.20±0.26±0.07. The extrapolation of GsM to its Q2 = 0 limit and comparison with calculations is also discussed.Item Parity-violating Electron Deuteron Scattering and the Proton’s Neutral Weak Axial Vector Form Factor(2004-03) Ito, T.M.; Averett, T.; Barkhuff, D.; Batigne, G.; Beck, D.H.; Beise, E.J.; Blake, A.; Breuer, H.; Carr, R.; Clasie, B.; Covrig, S.; Danagoulian, A.; Dodson, G.; Dow, K.; Dutta, D.; Farkhondeh, M.; Filippone, B.W.; Franklin, W.; Furget, C.; Gao, H.; Gao, J.; Gustafsson, K.; Hannelius, L.; Hasty, R.; Hawthorne-Allen, A.M.; Herda, M.C.; Jones, C.E.; King, P.; Korsch, W.; Kowalski, S.; Kox, S.; Kramer, K.; Lee, P.; Liu, J.; Martin, J.W.; McKeown, R.D.; Mueller, B.; Pitt, M.L.; Plaster, B.; Quemener, G.; Real, J. S.; Ritter, J.; Roche, J.; Savu, V.; Schiavilla, R.; Seely, J.; Spayde, D.; Suleiman, R.; Taylor, S.; Tieulent, R.; Tipton, B.; Tsentalovich, E.; Wells, S.P.; Yang, B.; Yuan, J.; Yun, J.; Zwart, T.; SAMPLE CollaborationWe report on a new measurement of the parity-violating asymmetry in quasielastic electron scat- tering from the deuteron at backward angles at Q2 = 0.038 (GeV/c)2. This quantity provides a de- termination of the neutral weak axial vector form factor of the nucleon, which can potentially receive large electroweak corrections. The measured asymmetry A = −3.51 ± 0.57 (stat) ± 0.58 (sys) ppm is consistent with theoretical predictions. We also report on updated results of the previous experiment at Q2 = 0.091 (GeV/c)2, which are also consistent with theoretical predictions.Item Measurement of the vector analyzing power in elastic electron-proton scattering as a probe of double photon exchange amplitudes(2001-05) Wells, S.P.; Averett, T.; Barkhuff, D.; Beck, D.H.; Beise, E.J.; Benson, C.; Breuer, H.; Carr, R.; Covrig, S.; DelCorso, J.; Dodson, G.; Eppstein, C.; Farkhondeh, M.; Filippone, B.W.; Forest, T.; Frasier, P.; Hasty, R.; Ito, T.M.; Jones, C.; Korsch, W.; Kowalski, S.; Lee, P.; Maneva, E.; McCarty, K.; McKeown, R.D.; Mikell, J.; Mueller, B.; Naik, P.; Pitt, M.L; Ritter, J.; Savu, V.; Spayde, D.T.; Sullivan, M.; Tieulent, R.; Tsentalovich, E.; Yang, B.; Zwart, T.; SAMPLE CollaborationWe report the first measurement of the vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q2 = 0.1 (GeV/c)2 and large scattering angles. This quantity should vanish in the single virtual photon exchange, plane wave impulse approximation for this reaction, and can therefore provide information on double photon exchange amplitudes for electro- magnetic interactions with hadronic systems. We find a non-zero value of A=-15.4±5.4 ppm. No calculations of this observable for nuclei other than spin 0 have been carried out in these kinematics, and the calculation using the spin orbit interaction from a charged point nucleus of spin 0 cannot describe these data.Item Strange Quark Contributions to Parity-Violating Asymmetries in the Backward Angle G0 Electron Scattering Experiment(2005-08) 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.; 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, T.H.; Versteegen, M.; Voutier, E.; Vulcan, W.; Wells, S.P.; Williamson, S.E.; Wood, S.A.; G0 CollaborationWe have measured parity-violating asymmetries in elastic electron-proton and quasi-elastic electron-deuteron scattering at Q2 = 0.22 and 0.63 GeV2. They are sensitive to strange quark contributions to currents in the nucleon, and to the nucleon axial current. The results indicate strange quark contributions of <∼ 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 current at these four-momentum transfers