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1. Measurement of the Spin Asymmetry in the Photoproduction of Pairs of High-pTHadrons at HERMES

Author

A. Airapetian, N. Akopov, M. Amarian, E. C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, B. Bains, C. Baumgarten, M. Beckmann, S. Belostotski, J. E. Belz, Th. Benisch, S. Bernreuther, N. Bianchi, J. Blouw, H. Böttcher, A. Borissov, J. Brack, S. Brauksiepe, B. Braun, W. Brückner, A. Brüll, H. J. Bulten, G. P. Capitani, P. Carter, P. Chumney, E. Cisbani, G. R. Court, P. F. Dalpiaz, E. De Sanctis, D. De Schepper, E. Devitsin, P. K. A. de Witt Huberts, P. Di Nezza, M. Düren, A. Dvoredsky, G. Elbakian, J. Ely, A. Fantoni, M. Ferstl, K. Fiedler, B. W. Filippone, H. Fischer, B. Fox, J. Franz, S. Frullani, M.-A. Funk, Y. Gärber, F. Garibaldi, G. Gavrilov, P. Geiger, V. Gharibyan, A. Golendukhin, G. Graw, O. Grebeniouk, P. W. Green, L. G. Greeniaus, C. Grosshauser, M. Guidal, A. Gute, W. Haeberli, J.-O. Hansen, D. Hasch, O. Häusser, F. H. Heinsius, R. Henderson, M. Henoch, R. Hertenberger, Y. Holler, R. J. Holt, W. Hoprich, H. Ihssen, M. Iodice, A. Izotov, H. E. Jackson, A. Jgoun, R. Kaiser, E. Kinney, A. Kisselev, P. Kitching, H. Kobayashi, N. Koch, K. Königsmann, M. Kolstein, H. Kolster, V. Korotkov, W. Korsch, V. Kozlov, L. H. Kramer, M. Kurisuno, G. Kyle, W. Lachnit, W. Lorenzon, N. C. R. Makins, F. K. Martens, J. W. Martin, F. Masoli, A. Mateos, M. McAndrew, K. McIlhany, R. D. McKeown, F. Meissner, F. M. Menden, A. Metz, N. Meyners, O. Mikloukho, C. A. Miller, M. A. Miller, R. Milner, A. Most, V. Muccifora, Y. Naryshkin, A. M. Nathan, F. Neunreither, M. Niczyporuk, W.-D. Nowak, T. G. O'Neill, R. Openshaw, J. Ouyang, B. R. Owen, S. F. Pate, S. Potashov, D. H. Potterveld, G. Rakness, R. Redwine, A. R. Reolon, R. Ristinen, K. Rith, P. Rossi, S. Rudnitsky, M. Ruh, D. Ryckbosch, Y. Sakemi, C. Scarlett, A. Schäfer, F. Schmidt, H. Schmitt, G. Schnell, K. P. Schüler, A. Schwind, J. Seibert, T.-A. Shibata, K. Shibatani, T Shin, V. Shutov, C. Simani, A. Simon, K. Sinram, P. Slavich, M. Spengos, E. Steffens, J. Stenger, J. Stewart, U. Stoesslein, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, B. Tipton, M. Tytgat, G. M. Uriuoli, R. van de Vyver, J. F. J. van den Brand, G. van der Steenhoven, J. J. van Hunen, M. C. Vetterli, V. Vikhrov, M. G. Vincter, J. Visser, E. Volk, W. Wander, J. Wendland, S. E. Williamson, T. Wise, K. Woller, S. Yoneyama, and H. Zohrabian

Subjects
HERMES experiment, Physics, Particle physics, media_common.quotation_subject, Hadron, General Physics and Astronomy, HERA, Polarization (waves), Deep inelastic scattering, Asymmetry, Gluon, Nuclear physics, High Energy Physics::Experiment, Nuclear Experiment, Storage ring, media_common
Abstract

We present a measurement of the longitudinal spin asymmetry A|| in photoproduction of pairs of hadrons with high transverse momentum pT. Data were accumulated by the HERMES experiment using a 27.5 GeV polarized positron beam and a polarized hydrogen target internal to the HERA storage ring. For h^+h^- pairs with _(pT)^(h1)>1.5GeV/c and _(pT)^(h2)>1.0GeV/c, the measured asymmetry is A_(||) = -0.28±0.12(stat)±0.02(syst). This negative value is in contrast to the positive asymmetries typically measured in deep inelastic scattering from protons, and is interpreted to arise from a positive gluon polarization.

Published
2000
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2. Observation of a Coherence Length Effect in Exclusiveρ0Electroproduction

Author

K. Ackerstaff, A. Airapetian, N. Akopov, I. Akushevich, M. Amarian, E. C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, B. Bains, S. Barrow, C. Baumgarten, M. Beckmann, St. Belostotski, J. E. Belz, Th. Benisch, S. Bernreuther, N. Bianchi, S. Blanchard, J. Blouw, H. Böttcher, A. Borissov, J. Brack, S. Brauksiepe, B. Braun, B. Bray, St. Brons, W. Brückner, A. Brüll, E. E. W. Bruins, H. J. Bulten, R. V. Cadman, G. P. Capitani, P. Carter, P. Chumney, E. Cisbani, G. R. Court, P. F. Dalpiaz, P. P. J. Delheij, E. De Sanctis, D. De Schepper, E. Devitsin, P. K. A. de Witt Huberts, P. Di Nezza, M. Düren, A. Dvoredsky, G. Elbakian, J. Ely, J. Emerson, A. Fantoni, A. Fechtchenko, M. Ferstl, D. Fick, K. Fiedler, B. W. Filippone, H. Fischer, H. T. Fortune, B. Fox, S. Frabetti, J. Franz, S. Frullani, M.-A. Funk, N. D. Gagunashvili, P. Galumian, H. Gao, Y. Gärber, F. Garibaldi, G. Gavrilov, P. Geiger, V. Gharibyan, V. Giordjian, A. Golendukhin, G. Graw, O. Grebeniouk, P. W. Green, L. G. Greeniaus, C. Grosshauser, M. G. Guidal, A. Gute, V. Gyurjyan, J. P. Haas, W. Haeberli, J.-O. Hansen, D. Hasch, O. Häusser, F. H. Heinsius, R. S. Henderson, Th. Henkes, M. Henoch, R. Hertenberger, Y. Holler, R. J. Holt, W. Hoprich, H. Ihssen, M. Iodice, A. Izotov, H. E. Jackson, A. Jgoun, C. Jones, R. Kaiser, E. Kinney, M. Kirsch, A. Kisselev, P. Kitching, H. Kobayashi, N. Koch, K. Königsmann, M. Kolstein, H. Kolster, V. Korotkov, W. Korsch, V. Kozlov, L. H. Kramer, B. Krause, V. G. Krivokhijine, M. Kückes, F. Kümmell, G. Kyle, W. Lachnit, W. Lorenzon, A. Lung, N. C. R. Makins, F. K. Martens, J. W. Martin, F. Masoli, A. Mateos, M. McAndrew, K. McIlhany, R. D. McKeown, F. Meissner, F. Menden, D. Mercer, A. Metz, N. Meyners, O. Mikloukho, C. A. Miller, M. A. Miller, R. G. Milner, V. Mitsyn, A. Most, R. Mozzetti, V. Muccifora, A. Nagaitsev, Y. Naryshkin, A. M. Nathan, F. Neunreither, M. Niczyporuk, W.-D. Nowak, M. Nupieri, P. Oelwein, H. Ogami, T. G. O'Neill, R. Openshaw, J. Ouyang, B. R. Owen, V. Papavassiliou, S. F. Pate, M. Pitt, H. R. Poolman, S. Potashov, D. H. Potterveld, B. Povh, G. Rakness, A. Reali, R. Redwine, A. R. Reolon, R. Ristinen, K. Rith, H. Roloff, G. Röper, P. Rossi, S. Rudnitsky, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, C. Scarlett, F. Schmidt, H. Schmitt, G. Schnell, K. P. Schüler, A. Schwind, J. Seibert, T.-A. Shibata, T. Shin, V. Shutov, C. Simani, A. Simon, K. Sinram, P. Slavich, J. Sowinski, M. Spengos, E. Steffens, J. Stenger, J. Stewart, F. Stock, U. Stoesslein, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, D. M. Thiessen, E. Thomas, B. Tipton, A. Trudel, M. Tytgat, G. M. Urciuoli, J. J. van Hunen, R. van de Vyver, J. F. J. van den Brand, G. van der Steenhoven, M. C. Vetterli, V. Vikhrov, M. Vincter, J. Visser, E. Volk, W. Wander, T. P. Welch, S. E. Williamson, T. Wise, T. Wölfel, K. Woller, S. Yoneyama, K. Zapfe-Düren, H. Zohrabian, and R. Zurmühle

Subjects
Physics, HERMES experiment, Particle physics, Meson, 010308 nuclear & particles physics, High Energy Physics::Lattice, High Energy Physics::Phenomenology, Nuclear Theory, General Physics and Astronomy, Virtual particle, 01 natural sciences, Coherence length, Positron energy, Nuclear physics, Deuterium, Nuclear transparency, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

Exclusive incoherent electroproduction of the ρ0(770) meson from 1H, 2H, 3He, and 14N targets has been studied by the HERMES experiment at squared four-momentum transfer Q^2>0.4 GeV^2 and positron energy loss ν from 9 to 20 GeV. The ratio of the 14N to 1H cross sections per nucleon, known as the nuclear transparency, was found to decrease with increasing coherence length of quark-antiquark fluctuations of the virtual photon. The data provide clear evidence of the interaction of the quark-antiquark fluctuations with the nuclear medium.

Published
1999
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3. Measurement of the proton spin structure function g(1)(p) with a pure hydrogen target

Author

A. Airapetian, N. Akopov, I. Akushevich, M. Amarian, E.C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, B. Bains, C. Baumgarten, M. Beckmann, St. Belostotski, E. Belz, Th. Benisch, S. Bernreuther, N. Bianchi, J. Blouw, H. Böttcher, A. Borissov, J. Brack, S. Brauksiepe, B. Braun, St. Brons, W. Brückner, A. Brüll, H.J. Bulten, G.P. Capitani, P. Carter, P. Chumney, E. Cisbani, G.R. Court, P.F. Dalpiaz, R. De Leo, E. De Sanctis, D. De Schepper, E. Devitsin, P.K.A. de Witt Huberts, P. Di Nezza, M. Düren, A. Dvoredsky, G. Elbakian, J. Ely, A. Fantoni, A. Fechtchenko, M. Ferstl, D. Fick, K. Fiedler, B.W. Filippone, H. Fischer, B. Fox, S. Frabetti, J. Franz, S. Frullani, M.-A. Funk, N.D. Gagunashvili, H. Gao, Y. Gärber, F. Garibaldi, G. Gavrilov, P. Geiger, V. Gharibyan, V. Giordjian, A. Golendukhin, G. Graw, O. Grebeniouk, P.W. Green, L.G. Greeniaus, C. Grosshauser, M. Guidal, A. Gute, W. Haeberli, J.-O. Hansen, D. Hasch, F.H. Heinsius, M. Henoch, R. Hertenberger, Y. Holler, R.J. Holt, W. Hoprich, H. Ihssen, M. Iodice, A. Izotov, H.E. Jackson, A. Jgoun, R. Kaiser, E. Kinney, A. Kisselev, P. Kitching, H. Kobayashi, N. Koch, K. Königsmann, M. Kolstein, H. Kolster, V. Korotkov, W. Korsch, V. Kozlov, L.H. Kramer, V.G. Krivokhijine, F. Kümmell, M. Kurisuno, G. Kyle, W. Lachnit, W. Lorenzon, N.C.R. Makins, S.I. Manaenkov, K. Martens, J.W. Martin, H. Marukyan, F. Masoli, A. Mateos, M. McAndrew, K. McIlhany, R.D. McKeown, F. Meißner, F. Menden, A. Metz, N. Meyners, O. Mikloukho, C.A. Miller, M.A. Miller, R. Milner, V. Mitsyn, A. Most, V. Muccifora, A. Nagaitsev, E. Nappi, Y. Naryshkin, A.M. Nathan, F. Neunreither, W.-D. Nowak, T.G. O'Neill, B.R. Owen, J. Ouyang, V. Papavassiliou, S.F. Pate, S. Potashov, D.H. Potterveld, G. Rakness, A. Reali, R. Redwine, A.R. Reolon, R. Ristinen, K. Rith, H. Roloff, P. Rossi, S. Rudnitsky, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, C. Scarlett, F. Schmidt, H. Schmitt, G. Schnell, K.P. Schüler, A. Schwind, J. Seibert, T.-A. Shibata, K. Shibatani, T. Shin, V. Shutov, C. Simani, A. Simon, K. Sinram, P. Slavich, M. Spengos, E. Steffens, J. Stenger, J. Stewart, U. Stößlein, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, B. Tipton, M. Tytgat, G.M. Urciuoli, R. Van de Vyver, J.F.J. van den Brand, G. van der Steenhoven, J.J. van Hunen, M.C. Vetterli, M. Vincter, J. Visser, E. Volk, W. Wander, S.E. Williamson, T. Wise, K. Woller, S. Yoneyama, H. Zohrabian, and (Astro)-Particles Physics

Subjects
Nuclear and High Energy Physics, Particle physics, POLARIZATION, Hydrogen, Positron beam, FOS: Physical sciences, chemistry.chemical_element, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), DEUTERON STRUCTURE FUNCTIONS, 0103 physical sciences, Proton spin crisis, Nuclear Experiment, 010306 general physics, Physics, DEEP-INELASTIC-SCATTERING, Range (particle radiation), F-2(P), 010308 nuclear & particles physics, Scattering, Structure function, HERA, 3. Good health, chemistry, Physics::Accelerator Physics, High Energy Physics::Experiment, Astrophysics::Earth and Planetary Astrophysics, Atomic physics, Storage ring
Abstract

A measurement of the proton spin structure function g1p(x,Q^2) in deep-inelastic scattering is presented. The data were taken with the 27.6 GeV longitudinally polarised positron beam at HERA incident on a longitudinally polarised pure hydrogen gas target internal to the storage ring. The kinematic range is 0.021, Comment: 7 pages, 3 figures, 1 table, RevTeX latex

Published
1998
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4. The HERMES spectrometer

Author

K. Ackerstaff, A. Airapetian, N. Akopov, M. Amarian, V. Andreev, E.C. Aschenauer, R. Avakian, H. Avakian, A. Avetissian, B. Bains, S. Barrow, W. Beckhusen, M. Beckmann, St. Belostotski, E. Belz, Th. Benisch, S. Bernreuther, N. Bianchi, J. Blouw, H. Böttcher, A. Borissov, J. Brack, B. Braun, B. Bray, S. Brons, W. Brückner, A. Brüll, H.J. Bulten, G.P. Capitani, P. Carter, P. Chumney, E. Cisbani, S. Clark, S. Colilli, H. Coombes, G.R. Court, P. Delheij, E. Devitsin, C.W. de Jager, E. De Sanctis, D. De Schepper, P.K.A. de Witt Huberts, P. Di Nezza, M. Doets, M. Düren, A. Dvoredsky, G. Elbakian, J. Emerson, A. Fantoni, A. Fechtchenko, M. Ferstl, D. Fick, K. Fiedler, B.W. Filippone, H. Fischer, H.T. Fortune, J. Franz, S. Frullani, M.-A. Funk, N.D. Gagunashvili, P. Galumian, H. Gao, Y. Gärber, F. Garibaldi, G. Gavrilov, P. Geiger, V. Gharibyan, V. Giordjian, F. Giuliani, A. Golendoukhin, B. Grabowski, G. Graw, O. Grebeniouk, P. Green, G. Greeniaus, M. Gricia, C. Grosshauser, A. Gute, J.P. Haas, K. Hakelberg, W. Haeberli, J.-O. Hansen, D. Hasch, O. Hausser, R. Henderson, Th. Henkes, R. Hertenberger, Y. Holler, R.J. Holt, H. Ihssen, A. Izotov, M. Iodice, H.E. Jackson, A. Jgoun, C. Jones, R. Kaiser, J. Kelsey, E. Kinney, M. Kirsch, A. Kisselev, P. Kitching, H. Kobayashi, E. Kok, K. Königsmann, M. Kolstein, H. Kolster, W. Korsch, S. Kozlov, V. Kozlov, R. Kowalczyk, L. Kramer, B. Krause, A. Krivchitch, V.G. Krivokhijine, M. Kueckes, P. Kutt, G. Kyle, W. Lachnit, R. Langstaff, W. Lorenzon, M. Lucentini, A. Lung, N. Makins, V. Maleev, S.I. Manaenkov, K. Martens, A. Mateos, K. McIlhany, R.D. McKeown, F. Meißner, F. Menden, D. Mercer, A. Metz, N. Meyners, O. Mikloukho, C.A. Miller, M.A. Miller, R. Milner, V. Mitsyn, G. Modrak, J. Morton, A. Most, R. Mozzetti, V. Muccifora, A. Nagaitsev, Y. Naryshkin, A.M. Nathan, F. Neunreither, M. Niczyporuk, W.-D. Nowak, M. Nupieri, P. Oelwein, H. Ogami, T.G. O’Neill, R. Openshaw, V. Papavassiliou, S.F. Pate, S. Patrichev, M. Pitt, H.J. Plett, H.R. Poolman, S. Potashov, D. Potterveld, B. Povh, V. Prahl, G. Rakness, V. Razmyslovich, R. Redwine, A.R. Reolon, R. Ristinen, K. Rith, H.O. Roloff, G. Röper, P. Rossi, S. Rudnitsky, H. Russo, D. Ryckbosch, Y. Sakemi, F. Santavenere, I. Savin, F. Schmidt, H. Schmitt, G. Schnell, K.P. Schüler, A. Schwind, T.-A. Shibata, T. Shin, B. Siebels, A. Simon, K. Sinram, W.R. Smythe, J. Sowinski, M. Spengos, K. Sperber, E. Steffens, J. Stenger, J. Stewart, F. Stock, U. Stößlein, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, D. Thiessen, B. Tipton, V. Trofimov, A. Trudel, M. Tytgat, G.M. Urciuoli, R. Van de Vyver, J.F.J. van den Brand, G. van der Steenhoven, J.J. van Hunen, D. van Westrum, A. Vassiliev, M.C. Vetterli, M.G. Vincter, E. Volk, W. Wander, T.P. Welch, S.E. Williamson, T. Wise, G. Wöbke, K. Woller, S. Yoneyama, K. Zapfe-Düren, T. Zeuli, H. Zohrabian, and (Astro)-Particles Physics

Subjects
HERMES experiment, Nuclear and High Energy Physics, Particle physics, semi-inclusive scattering, (e, Physics::Instrumentation and Detectors, Cherenkov detector, CALORIMETERS, FOS: Physical sciences, deep inelastic lepton scattering, (e,e''h), Tracking (particle physics), Particle identification, High Energy Physics - Experiment, INORGANIC MATERIALS, law.invention, High Energy Physics - Experiment (hep-ex), e''h), GAS-MIXTURES, law, Nuclear Experiment, Instrumentation, Physics, Calorimeter (particle physics), Spectrometer, PERFORMANCE, magnetic spectrometer, Deep inelastic scattering, Transition radiation detector, CHAMBERS, High Energy Physics::Experiment
Abstract

The HERMES experiment is collecting data on inclusive and semi-inclusive deep inelastic scattering of polarised positrons from polarised targets of H, D, and He. These data give information on the spin structure of the nucleon. This paper describes the forward angle spectrometer built for this purpose. The spectrometer includes numerous tracking chambers (micro-strip gas chambers, drift and proportional chambers) in front of and behind a 1.3 T.m magnetic field, as well as an extensive set of detectors for particle identification (a lead-glass calorimeter, a pre-shower detector, a transition radiation detector, and a threshold Cherenkov detector). Two of the main features of the spectrometer are its good acceptance and identification of both positrons and hadrons, in particular pions. These characteristics, together with the purity of the targets, are allowing HERMES to make unique contributions to the understanding of how the spins of the quarks contribute to the spin of the nucleon., 37 pages, 32 figures, 4 tables

Published
1998
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5. Deuteron threshold electrodisintegration at high momentum transfer

Author

R. Miskimen, W. M. Schmitt, M. Spengos, S. Churchwell, C. F. Williamson, T. C. Yates, G. A. Peterson, P. E. Bosted, J. Martino, B. Frois, K. Wang, R. S. Hicks, J.D. Zumbro, A. Hotta, W. Turchinetz, S.K. Platchkov, K. S. Lee, and H. Baghaei

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Meson, Scattering, Nuclear Theory, Quark model, Momentum transfer, Nuclear physics, Deuterium, Nuclear force, Nuclear Experiment, Nucleon, Relativistic quantum chemistry
Abstract

Absolute differential cross sections for the threshold electrodisintegration of the deuteron with good resolution were measured at a laboratory scattering angle of 160\ifmmode^\circ\else\textdegree\fi{} for five values of ${Q}^{2}$ ranging from 8.66 to $42.4{\mathrm{fm}}^{\mathrm{\ensuremath{-}}2}.$ Comparisons of the data averaged over ${E}_{\mathrm{np}}$ from 0 to 3 MeV and from 0 to10 MeV are made with nonrelativistic meson exchange calculations. These calculations are sensitive to the nucleon electromagnetic form factors, nucleon-nucleon potential, and relativistic effects. The data are also compared with a hybrid quark-hadron model calculation that describes the deuteron as a six-quark cluster for the short range part of the interaction. Some of these calculations can describe the data reasonably well over certain ranges of ${Q}^{2};$ however, none of these calculations can accurately describe the data over the entire measured ${Q}^{2}$ range.

Published
1997
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6. Evidence For Virtual Compton-Scattering From The Proton

Author

B. W. Filippone, Jenny Nelson, Kisoo Lee, Haiyan Gao, D. H. Potterveld, D. F. Geesaman, E. R. Kinney, H. E. Jackson, B. Zeidman, S. E. Rock, R. D. McKeown, K. van Bibber, B. Mueller, Michael Chapman, M. B. Epstein, K. P. Coulter, R. A. Gearhart, Jim Napolitano, Wolfgang Lorenzon, D. J. Margaziotis, J. Arrington, E. J. Beise, H. J. Bulten, P.L. Anthony, J.-O. Hansen, F. S. Dietrich, S. E. Kuhn, J. F. J. van den Brand, P. E. Bosted, G. G. Petratos, J. E. Belz, Thomas O'Neill, L. H. Tao, M. Spengos, Rolf Ent, V. Papavassiliou, Z. M. Szalata, A. Lung, D. A. Wasson, R. G. Arnold, C. E. Jones, C. E. Keppel, Ross Milner, James L. White, R. J. Holt, and Naomi C R Makins

Subjects
Physics, Photon, Proton, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Compton scattering, Electron, Compton wavelength, MAGNETIC FORM-FACTORS, Inelastic scattering, Q(2)=1.75, Linear particle accelerator, Nuclear physics, (GEV/C)(2), Physics::Accelerator Physics, Nucleon, Nuclear Experiment
Abstract

In virtual Compton scattering an electron is scattered off a nucleon such that the nucleon emits a photon. We show that these events can be selected experimentally, and present the first evidence for virtual Compton scattering from the proton in data obtained at the Stanford Linear Accelerator Center. The angular and energy dependence of the data is well described by a calculation that includes the coherent sum of electron and proton radiation.

Published
1995
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7. Momentum transfer dependence of nuclear transparency from the quasielasticC12(e,e’p) reaction

Author

L. H. Tao, B. Mueller, C. E. Keppel, van Bibber K, B. W. Filippone, C. E. Jones, D. H. Potterveld, R. J. Holt, Naomi C R Makins, R. A. Gearhart, R. Ent, B. Zeidman, D. J. Margaziotis, M. B. Epstein, K. P. Coulter, Papavassiliou, S. E. Rock, Z. M. Szalata, Thomas O'Neill, H. J. Bulten, E. Belz, Haiyan Gao, J. O. Hansen, S. E. Kuhn, J. Nelson, Ross Milner, J. Arrington, H. E. Jackson, Michael Chapman, E. J. Beise, P. E. Bosted, M. Spengos, van den Brand Jf, Patratos Gg, J. L. White, E. R. Kinney, A. Lung, P. L. Anthony, R. G. Arnold, R. D. McKeown, Wolfgang Lorenzon, Kisoo Lee, D. F. Geesaman, J. Napolitano, and F. S. Dietrich

Subjects
Nuclear reaction, Physics, Scattering, Nuclear Theory, Momentum transfer, Hadron, General Physics and Astronomy, Nuclear physics, Baryon, Nuclear transparency, Atomic physics, Nuclear Experiment, Nucleon, Lepton
Abstract

The cross section for quasielastic ^(12)C(e,e’p) scattering has been measured at momentum transfer Q^2=1, 3, 5, and 6.8 (GeV/c)^2. The results are consistent with scattering from a single nucleon as the dominant process. The nuclear transparency is obtained and compared with theoretical calculations that incorporate color transparency effects. No significant rise of the transparency with Q^2 is observed.

Published
1994
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8. Determination of the Deep Inelastic Contribution to the generalised Gerasimov-Drell-Hearn Intregral for the Proton and Neutron

Author

K. Ackerstaff, A. Airapetian, N. Akopov, I. Akushevich, M. Amarian, E.C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, B. Bains, S. Barrow, C. Baumgarten, M. Beckmann, S. Belostotski, J.E. Belz, T. Benisch, S. Bernreuther, N. Bianchi, S. Blanchard, J. Blouw, H. Böttcher, A. Borissov, J. Brack, S. Brauksiepe, B. Braun, B. Bray, S. Brons, W. Brückner, A. Brüll, E.E.W. Bruins, H.J. Bulten, R. Cadman, G.P. Capitani, P. Carter, P. Chumney, E. Cisbani, G.R. Court, P.F. Dal Piaz, P.P.J. Delheij, E. De Sanctis, D. De Schepper, E. Devitsin, P.K.A. de Witt Huberts, P. Di Nezza, M. Düren, A. Dvoredsky, G. Elbakian, J. Ely, J. Emerson, A. Fantoni, A. Fechtchenko, M. Ferstl, D. Fick, K. Fiedler, B.W. Filippone, H. Fischer, H.T. Fortune, B. Fox, S. Frabetti, J. Franz, S. Frullani, M.-A. Funk, N.D. Gagunashvili, P. Galumian, H. Gao, Y. Gärber, F. Garibaldi, G. Gavrilov, P. Geiger, V. Gharibyan, V. Gyurjyan, A. Golendoukhin, G. Graw, O. Grebeniouk, P.W. Green, L.G. Greeniaus, C. Grosshauser, M.G. Guidal, A. Gute, J.P. Haas, W. Haeberli, J.-O. Hansen, D. Hasch, O. Häusser, F.H. Heinsius, R. Henderson, T. Henkes, M. Henoch, R. Hertenberger, Y. Holler, R.J. Holt, W. Hoprich, H. Ihssen, M. Iodice, A. Izotov, H.E. Jackson, A. Jgoun, C. Jones, R. Kaiser, E. Kinney, M. Kirsch, A. Kisselev, P. Kitching, H. Kobayashi, N. Koch, K. Königsmann, M. Kolstein, H. Kolster, V. Korotkov, W. Korsch, V. Kozlov, L.H. Kramer, B. Krause, V.G. Krivokhijine, M. Kückes, F. Kümmell, G. Kyle, W. Lachnit, W. Lorenzon, A. Lung, N.C.R. Makins, S.I. Manaenkov, F.K. Martens, J.W. Martin, F. Masoli, A. Mateos, M. McAndrew, K. McIlhany, R.D. McKeown, F. Meissner, F. Menden, D. Mercer, A. Metz, N. Meyners, O. Mikloukho, C.A. Miller, M.A. Miller, R. Milner, V. Mitsyn, A. Most, R. Mozzetti, V. Muccifora, A. Nagaitsev, Y. Naryshkin, A.M. Nathan, F. Neunreither, M. Niczyporuk, W.-D. Nowak, M. Nupieri, P. Oelwein, H. Ogami, T.G. O'Neill, R. Openshaw, J. Ouyang, B. Owen, V. Papavassiliou, S.F. Pate, M. Pitt, H.R. Poolman, S. Potashov, D.H. Potterveld, G. Rakness, A. Reali, R. Redwine, A.R. Reolon, R. Ristinen, K. Rith, H. Roloff, G. Röper, P. Rossi, S. Rudnitsky, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, C. Scarlett, F. Schmidt, H. Schmitt, G. Schnell, K.P. Schüler, A. Schwind, J. Seibert, T.-A. Shibata, T. Shin, V. Shutov, M.C. Simani, A. Simon, K. Sinram, P. Slavich, W.R. Smythe, J. Sowinski, M. Spengos, E. Steffens, J. Stenger, J. Stewart, F. Stock, U. Stoesslein, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, D.M. Thiessen, E. Thomas, B. Tipton, A. Trudel, M. Tytgat, G.M. Urciuoli, J.J. van Hunen, R. van de Vyver, J.F.J. van den Brand, G. van der Steenhoven, M.C. Vetterli, M. Vincter, J. Visser, E. Volk, W. Wander, T.P. Welch, S.E. Williamson, T. Wise, K. Woller, S. Yoneyama, K. Zapfe-Düren, H. Zohrabian, R. Zurmühle, and (Astro)-Particles Physics

Subjects
Nuclear and High Energy Physics, Particle physics, Proton, Nuclear Theory, PARTON MODEL, Virtual particle, FOS: Physical sciences, 01 natural sciences, High Energy Physics - Experiment, POLARIZED HE-3, SUM-RULES, Cross section (physics), High Energy Physics - Experiment (hep-ex), 0103 physical sciences, SCATTERING, Neutron, STRUCTURE-FUNCTION G(1)(N), 010306 general physics, Nuclear Experiment, NUCLEON, Quantum chromodynamics, Physics, 010308 nuclear & particles physics, Absorption cross section, Deep inelastic scattering, SPIN STRUCTURE-FUNCTION, RESONANCE REGION, High Energy Physics::Experiment, E-P, Nucleon
Abstract

The virtual photon absorption cross section differences [sigma_1/2-sigma_3/2] for the proton and neutron have been determined from measurements of polarised cross section asymmetries in deep inelastic scattering of 27.5 GeV longitudinally polarised positrons from polarised 1H and 3He internal gas targets. The data were collected in the region above the nucleon resonances in the kinematic range nu < 23.5 GeV and 0.8 GeV**2 < Q**2 < 12 GeV**2. For the proton the contribution to the generalised Gerasimov-Drell-Hearn integral was found to be substantial and must be included for an accurate determination of the full integral. Furthermore the data are consistent with a QCD next-to-leading order fit based on previous deep inelastic scattering data. Therefore higher twist effects do not appear significant., 6 pages, 3 figures, 1 table, revtex

Published
1998
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9. The Flavor Asymmetry of the Light Quark Sea from Semi-inclusive Deep-inelastic Scattering

Author

K. Ackerstaff, A. Airapetian, N. Akopov, I. Akushevich, M. Amarian, E. C. Ashenauer, H. Avakian, R. Avakian, A. Avetissian, B. Bains, C. Baumgarten, M. Beckmann, St. Belostotski, J. E. Belz, Th. Benisch, S. Bernreuther, N. Bianchi, J. Blouw, H. Böttcher, A. Borissov, J. Brack, S. Brauksiepe, B. Braun, B. Bray, St. Brons, W. Brückner, A. Brüll, E. E. W. Bruins, H. J. Bulten, R. V. Cadman, G. P. Capitani, P. Carter, P. Chumney, E. Cisbani, G. R. Court, P. F. Dalpiaz, E. De Sanctis, D. De Schepper, E. Devitsin, P. K. A. de Witt Huberts, P. Di Nezza, M. Düren, A. Dvoredsky, G. Elbakian, A. Fantoni, A. Fechtchenko, M. Ferstl, K. Fiedler, B. W. Filippone, H. Fischer, B. Fox, J. Franz, S. Frullani, M.-A. Funk, N. D. Gagunashvili, H. Gao, Y. Gärber, F. Garibaldi, G. Gavrilov, P. Geiger, V. Gharibyan, V. Giordjian, A. Golendukhin, G. Graw, O. Grebeniouk, P. W. Green, L. G. Greeniaus, C. Grosshauser, A. Gute, W. Haeberli, J.-O. Hansen, D. Hasch, O. Häusser, R. Henderson, Th. Henkes, M. Henoch, R. Hertenberger, Y. Holler, R. J. Holt, W. Hoprich, H. Ihssen, M. Iodice, A. Izotov, H. E. Jackson, A. Jgoun, R. Kaiser, E. Kinney, A. Kisselev, P. Kitching, H. Kobayashi, N. Koch, K. Königsmann, M. Kolstein, H. Kolster, V. Korotkov, W. Korsch, V. Kozlov, L. H. Kramer, V. G. Krivokhijine, M. Kurisuno, G. Kyle, W. Lachnit, W. Lorenzon, N. C. R. Makins, S. I. Manaenkov, F. K. Martens, J. W. Martin, F. Masoli, A. Mateos, M. McAndrew, K. McIlhany, R. D. McKeown, F. M. Menden, F. Meissner, A. Metz, N. Meyners, O. Mikloukho, C. A. Miller, M. A. Miller, R. Milner, V. Mitsyn, A. Most, R. Mozzetti, V. Muccifora, A. Nagaitsev, Y. Naryshkin, A. M. Nathan, F. Neunreither, M. Niczyporuk, W.-D. Nowak, M. Nupieri, T. G. O'Neill, J. Ouyang, B. R. Owen, V. Papavassiliou, S. F. Pate, M. Pitt, S. Potashov, D. H. Potterveld, G. Rakness, A. Reali, R. Redwine, A. R. Reolon, R. Ristinen, K. Rith, H. Roloff, P. Rossi, S. Rudnitsky, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, F. Schmidt, H. Schmitt, G. Schnell, K. P. Schüler, A. Schwind, T.-A. Shibata, K. Shibatani, T. Shin, V. Shutov, C. Simani, A. Simon, K. Sinram, P. Slavich, M. Spengos, E. Steffens, J. Stenger, J. Stewart, U. Stoesslein, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, B. Tipton, M. Tytgat, G. M. Urciuoli, J. J. van Hunen, R. van de Vyver, J. F. J. van den Brand, G. van der Steenhoven, M. C. Vetterli, M. G. Vincter, E. Volk, W. Wander, S. E. Williamson, T. Wise, K. Woller, S. Yoneyama, H. Zohrabian, and (Astro)-Particles Physics

Subjects
Quark, Particle physics, Proton, media_common.quotation_subject, High Energy Physics::Lattice, Nuclear Theory, General Physics and Astronomy, FOS: Physical sciences, PROTON, 01 natural sciences, 7. Clean energy, Asymmetry, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Pion, DRELL-YAN PROCESS, 0103 physical sciences, 010306 general physics, NUCLEON, Nuclear Experiment, media_common, Physics, 010308 nuclear & particles physics, Scattering, High Energy Physics::Phenomenology, Deep inelastic scattering, Deuterium, PARTON DISTRIBUTIONS, High Energy Physics::Experiment, Nucleon, BREAKING
Abstract

The flavor asymmetry of the light quark sea of the nucleon is determined in the kinematic range 0.02, Comment: 7 Pages, 2 figures, RevTeX format; slight revision in text, small change in extraction of dbar-ubar and comparison with a high q2 parameterization

Published
1998
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10. Two body photodisintegration of the deuteron up to 2.8 GeV

Author

R. Gearhart, Douglas H Beck, Richard G. Milner, M. Epstein, Z. M. Szalata, John Nelson, C. E. Keppel, K. van Bibber, R. D. McKeown, K. P. Coulter, K. Lee, B. Mueller, Wolfgang Lorenzon, Jim Napolitano, H. J. Bulten, P. Bosted, D. J. Margaziotis, Haiyan Gao, P. L. Anthony, A. Lung, H. E. Jackson, S. E. Kuhn, J. F. J. van den Brand, L. H. Tao, R. Ent, J. E. Belz, E. R. Kinney, V. Papavassiliou, Thomas O'Neill, E. J. Beise, J. Arrington, J. O. Hansen, M. Spengos, D. H. Potterveld, G. G. Petratos, C. E. Jones, R. J. Holt, S. E. Rock, Michael Chapman, F. S. Dietrich, Z. E. Meziani, James L. White, Naomi C R Makins, D. F. Geesaman, R. G. Arnold, B. Zeidman, R. E. Segel, B. W. Filippone, Seestrom, S. J., and ZEUS at HERA (IHEF, IoP, FNWI)

Subjects
Physics, Elastic scattering, Nuclear reaction, Quantum chromodynamics, Particle physics, Photon, Hadron, Momentum transfer, Nuclear Theory, General Physics and Astronomy, Nuclear physics, Cross section (physics), Deuterium, Photodisintegration, Neutron, High Energy Physics::Experiment, Nuclear Experiment
Abstract

Measurements were performed for the photodisintegration cross section of the deuteron for photon energies from 1.6 to 2.8 GeV and center-of-mass angles from 37° to 90°. The measured energy dependence of the cross section at θ_(c.m.)=90° is in agreement with the constituent counting rules.

Published
1995

11. Exclusive electron scattering from deuterium at high momentum transfer

Author

P. E. Bosted, M. Spengos, J. Arrington, S. E. Kuhn, M. Epstein, H. J. Bulten, R. Ent, R. D. McKeown, Haiyan Gao, Wolfgang Lorenzon, Z. M. Szalata, J. O. Hansen, B. W. Filippone, Ross Milner, F. S. Dietrich, K. P. Coulter, J. L. White, H. E. Jackson, E. R. Kinney, Thomas O'Neill, B. Mueller, G. G. Petratos, L. H. Tao, P. L. Anthony, J. Nelson, J. F. J. van den Brand, D. H. Potterveld, Kisoo Lee, V. Papavassiliou, Michael Chapman, D. J. Margaziotis, A. Lung, R. Gearhart, S. E. Rock, C. E. Jones, K. van Bibber, E. J. Beise, J. Napolitano, B. Zeidman, E. Belz, D. F. Geesaman, R. G. Arnold, C. E. Keppel, R. J. Holt, Naomi C R Makins, and Other Research IHEF (IoP, FNWI)

Subjects
Physics, Scattering, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Momentum transfer, General Physics and Astronomy, Particle accelerator, Observable, Electron, law.invention, Nuclear physics, Momentum, Deuterium, law, Atomic physics, QUARK EXCHANGE, Nuclear Experiment, Electron scattering, Caltech Library Services
Abstract

Cross sections are presented for the reaction 2H(e,e′p)n for momentum transfers in the range 1.2≤Q^2≤6.8 (GeV/c)^2 and for missing momenta from 0 to 250 MeV/c. The longitudinal-transverse interference structure function has been separated at Q^2 = 1.2 (GeV/c)^2. The observables are compared to calculations performed in nonrelativistic and relativistic frameworks. The data are best described by a fully relativistic calculation.

Published
1995

12. Measurements of deuteron threshold electrodisintegration: A probe of short-range meson exchange

Author

W. Turchinetz, Douglas H Beck, S.K. Platchkov, A. Hotta, R. S. Hicks, T. C. Yates, J. Martino, W. M. Schmitt, J.D. Zumbro, C. F. Williamson, K. S. Lee, S. Churchwell, P. E. Bosted, B. Frois, G. A. Peterson, M. Spengos, K. Wang, R. A. Miskimen, and H. Baghaei

Subjects
Physics, Particle physics, Meson, Nuclear Theory, Quark model, Hadron, Form factor (quantum field theory), General Physics and Astronomy, Elementary particle, Nuclear physics, Sensitivity (control systems), Nuclear Experiment, Nucleon, Energy (signal processing)
Abstract

The threshold electrodisintegration of the deuteron was measured with good energy resolution to a maximum four-momentum transfer squared of 42 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}2}$. The data are compared with meson exchange calculations that show sensitivity to the choice of exchange-current form factor, the nucleon electromagnetic form factors, and the nucleon-nucleon potential. While conventional theories can give a reasonable description of the data, comparison of the data with quark cluster calculations shows poor agreement.

Published
1991

13. Measurement of Longitudinal Spin Transfer to Lambda Hyperons in Deep Inelastic Lepton Scattering

Author

Th. Benisch, H. E. Jackson, V. G. Krivokhijine, A. Nagaitsev, S. Bernreuther, T. A. Shibata, Haiyan Gao, C. Baumgarten, M. Amarian, B. Braun, Michel Vetterli, F. Menden, S. Brauksiepe, Andrey V. Izotov, R.O. Avakian, Evaristo Cisbani, G. Rakness, E. Devitsin, V. A. Kozlov, W.-D. Nowak, N. Akopov, A. Metz, Ralf Kaiser, M. Guidal, A. Reali, Valeria Muccifora, A.O. Mateos, B. D. Fox, A. R. Reolon, A. Avetissian, W. Lachnit, A. Airapetian, G. S. Kyle, V. A. Korotkov, M. Iodice, E. Steffens, M. Henoch, A. Kisselev, A. Borissov, Robert Henderson, M. Kurisuno, M. Sutter, G. M. Urciuoli, A. Simon, G. Gavrilov, M. Düren, R. D. McKeown, P. Geiger, R. J. Holt, G. P. Capitani, J. van Hunen, Klaus Rith, M. Kolstein, M. Ruh, Adel Terkulov, F. Masoli, J. Visser, A. Dvoredsky, L. G. Greeniaus, S. Yoneyama, R. Mussa, Wolfgang Lorenzon, B. Tipton, F. Neunreither, P. Carter, R. Openshaw, B. R. Owen, E. De Sanctis, C. Scarlett, H. Schmitt, H. Avakian, Y. Gärber, U. Stosslein, Y. Holler, Michael Tytgat, S. Taroian, P. Rossi, Salvatore Frullani, E. E. W. Bruins, A. Fechtchenko, B. Bray, Franco Garibaldi, P. F. Dalpiaz, K. Königsmann, R. P. Redwine, E. Thomas, Michael Pitt, A. Brüll, C. A. Miller, G. Schnell, W. Wander, J. Ely, A. Jgoun, G. Elbakian, A. Gute, W. Brückner, S. E. Williamson, S. Belostotski, P.K.A. de Witt Huberts, P. Kitching, Ross Milner, H. Kolster, O. Grebeniouk, S. I. Manaenkov, Alessandra Fantoni, T. Shin, M. Nupieri, G. van der Steenhoven, G. Graw, A. Golendukhin, H. J. Bulten, Alan M. Nathan, F.H. Heinsius, P. Chumney, E. C. Aschenauer, E. R. Kinney, V. Shutov, V. Vikhrov, B. Bains, L. H. Kramer, Wolfgang Korsch, Y. Naryshkin, C. Simani, Naomi C R Makins, F. Meissner, V. Gyurjyan, Manuella Vincter, M.-A. Funk, E. Volk, Ralf Hertenberger, H. Ihssen, J. P. Haas, A. Schwind, Hiroaki Kobayashi, K. Fiedler, K. Shibatani, K. Woller, M. Spengos, J. Franz, K. McIlhany, I.A. Savin, P.W. Green, G.R. Court, M. McAndrew, H. Tallini, J. W. Martin, S. Rudnitsky, Dirk Ryckbosch, Thomas O'Neill, K. P. Schüler, N. Koch, Nicola Bianchi, O. Mikloukho, S. Potashov, H. Zohrabian, M. Kirsch, P. Di Nezza, M. A. Miller, C. Grosshauser, R. A. Ristinen, J. M. Niczyporuk, N. Meyners, J.-O. Hansen, M. Ferstl, M. Bouwhuis, H. Böttcher, S. F. Pate, V. Papavassiliou, R. Van de Vyver, P. Slavich, Jeffrey Brack, J. Stenger, J. E. Belz, J. Stewart, W. Haeberli, P. Lenisa, J. Seibert, J. Wendland, D. Hasch, B. W. Filippone, J. Blouw, D. H. Potterveld, W. Hoprich, H. Fischer, O. Häusser, D. De Schepper, K. Sinram, T. Wise, V. Gharibyan, F. Schmidt, M. Beckmann, J. F. J. van den Brand, Yasuhiro Sakemi, Jinsong Ouyang, M. Hartig, S. Brons, F. K. Martens, and (Astro)-Particles Physics

Subjects
Photon, HERMES, (p pi-) [mass spectrum], PROTON, 01 natural sciences, polarization [up], High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), 27.5 GeV, angular distribution, deep inelastic scattering [positron p], STRUCTURE-FUNCTION G(1)(P), NUCLEON, Nuclear Experiment, Physics, BARYONS, Spin polarization, HERA, Helicity, DESY HERA Stor, polarization [Lambda], +p+pi%22">Lambda --> p pi, Quark, fragmentation [up], Nuclear and High Energy Physics, Particle physics, electroproduction [Lambda], MUON SCATTERING, FOS: Physical sciences, Nuclear physics, ASYMMETRIES, 0103 physical sciences, ddc:530, SDG 7 - Affordable and Clean Energy, 010306 general physics, Z-DECAYS, quark model parton, 010308 nuclear & particles physics, Hyperon, (LAMBDA)OVER-BAR POLARIZATION, Deep inelastic scattering, conservation law [helicity], DEUTERON, High Energy Physics::Experiment, polarized beam [positron], +Lambda%22">positron p --> Lambda, POLARIZED QUARK DISTRIBUTIONS, Lepton, experimental results
Abstract

Spin transfer in deep-inelastic Lambda electroproduction has been studied with the HERMES detector using the 27.6 GeV polarized positron beam in the HERA storage ring. For an average fractional energy transfer = 0.45, the longitudinal spin transfer from the virtual photon to the Lambda has been extracted. The spin transfer along the Lambda momentum direction is found to be 0.11 +/- 0.17 (stat) +/- 0.03 (sys); similar values are found for other possible choices for the longitudinal spin direction of the Lambda. This result is the most precise value obtained to date from deep-inelastic scattering with charged lepton beams, and is sensitive to polarized up quark fragmentation to hyperon states. The experimental result is found to be in general agreement with various models of the Lambda spin content, and is consistent with the assumption of helicity conservation in the fragmentation process., Comment: 8 pages, 3 figures; new version has an expanded discussion and small format changes

Published
2001
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