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1. The HERMES Back Drift Chambers

Author

al, S. Bernreuther et

Subjects
High Energy Physics - Experiment
Abstract

The tracking system of the HERMES spectrometer behind the bending magnet consists of two pairs of large planar 6-plane drift chambers. The design and performance of these chambers is described. This description comprises details on the mechanical and electronical design, information about the gas mixture used and its properties, results on alignment, calibration, resolution, and efficiencies, and a discussion of the experience gained through the first three years of operation., Comment: 21 pages, LaTex, 16 figures included

Published
1998
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2. Hard exclusive electroproduction of π+π− pairs

Author

A. Airapetian, N. Akopov, Z. Akopov, M. Amarian, V.V. Ammosov, A. Andrus, E.C. Aschenauer, W. Augustyniak, R. Avakian, A. Avetissian, E. Avetissian, P. Bailey, D. Balin, V. Baturin, M. Beckmann, S. Belostotski, S. Bernreuther, N. Bianchi, H.P. Blok, H. Böttcher, A. Borissov, A. Borysenko, M. Bouwhuis, J. Brack, A. Brüll, V. Bryzgalov, G.P. Capitani, T. Chen, G. Ciullo, M. Contalbrigo, P.F. Dalpiaz, R. De Leo, M. Demey, L. De Nardo, E. De Sanctis, E. Devitsin, P. Di Nezza, M. Düren, M. Ehrenfried, A. Elalaoui-Moulay, G. Elbakian, F. Ellinghaus, U. Elschenbroich, R. Fabbri, A. Fantoni, A. Fechtchenko, L. Felawka, S. Frullani, G. Gapienko, V. Gapienko, F. Garibaldi, K. Garrow, E. Garutti, G. Gavrilov, V. Gharibyan, G. Graw, O. Grebeniouk, L.G. Greeniaus, I.M. Gregor, K.A. Griffioen, K. Hafidi, M. Hartig, D. Hasch, D. Heesbeen, M. Henoch, R. Hertenberger, W.H.A. Hesselink, A. Hillenbrand, M. Hoek, Y. Holler, B. Hommez, G. Iarygin, A. Ivanilov, A. Izotov, H.E. Jackson, A. Jgoun, R. Kaiser, E. Kinney, A. Kisselev, M. Kopytin, V. Korotkov, V. Kozlov, B. Krauss, V.G. Krivokhijine, L. Lagamba, L. Lapikás, A. Laziev, P. Lenisa, P. Liebing, L.A. Linden-Levy, K. Lipka, W. Lorenzon, H. Lu, J. Lu, S. Lu, B.-Q. Ma, B. Maiheu, N.C.R. Makins, Y. Mao, B. Marianski, H. Marukyan, F. Masoli, V. Mexner, N. Meyners, O. Mikloukho, C.A. Miller, Y. Miyachi, V. Muccifora, A. Nagaitsev, E. Nappi, Y. Naryshkin, A. Nass, M. Negodaev, W.-D. Nowak, K. Oganessyan, H. Ohsuga, A. Osborne, N. Pickert, S. Potashov, D.H. Potterveld, M. Raithel, D. Reggiani, P.E. Reimer, A. Reischl, A.R. Reolon, C. Riedl, K. Rith, G. Rosner, A. Rostomyan, L. Rubacek, J. Rubin, D. Ryckbosch, Y. Salomatin, I. Sanjiev, I. Savin, A. Schäfer, C. Schill, G. Schnell, K.P. Schüler, J. Seele, R. Seidl, B. Seitz, R. Shanidze, C. Shearer, T.-A. Shibata, V. Shutov, K. Sinram, W. Sommer, M. Stancari, M. Statera, E. Steffens, J.J.M. Steijger, H. Stenzel, J. Stewart, F. Stinzing, P. Tait, H. Tanaka, S. Taroian, B. Tchuiko, A. Terkulov, A. Tkabladze, A. Trzcinski, M. Tytgat, A. Vandenbroucke, P. van der Nat, G. van der Steenhoven, Y. van Haarlem, M.C. Vetterli, V. Vikhrov, M.G. Vincter, C. Vogel, M. Vogt, J. Volmer, C. Weiskopf, J. Wendland, J. Wilbert, G. Ybeles Smit, Y. Ye, Z. Ye, S. Yen, B. Zihlmann, and P. Zupranski

Subjects
Physics, HERMES experiment, Nuclear and High Energy Physics, Particle physics, Meson, Isovector, 010308 nuclear & particles physics, Isoscalar, Nuclear Theory, Parton, 01 natural sciences, Helicity, Nuclear physics, Pion, 0103 physical sciences, High Energy Physics::Experiment, Invariant mass, Nuclear Experiment, 010306 general physics
Abstract

Hard exclusive electroproduction of π + π − pairs off hydrogen and deuterium targets has been studied by the HERMES experiment at DESY. Legendre moments 〈 P 1 〉 and 〈 P 3 〉 of the angular distributions of π + mesons in the center-of-mass frame of the pair have been measured for the first time. Their dependence on the π + π − invariant mass can be understood as being due to the interference between relative P -wave (isovector) and S -, D -wave (isoscalar) states of the two pions. The increase in magnitude of 〈 P 1 〉 as Bjorken x increases is interpreted in the framework of generalized parton distributions as an enhancement of flavour non-singlet q q ¯ exchange for larger values of x , which leads to a sizable admixture of isoscalar and isovector pion pairs. In addition, the interference between P -wave and D -wave states separately for transverse and longitudinal pion pairs has been studied. The data indicate that in the f 2 ( 1270 ) region at 〈 Q 2 〉 = 3 GeV 2 higher-twist effects can be as large as the leading-twist longitudinal component.

Published
2004

3. Erratum to: 'Nuclear effects on R=σ/σ in deep-inelastic scattering'

Author

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

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Cross section.transverse, Deuterium, Bibliography, Deep inelastic scattering
Published
2003

4. The HERMES dual-radiator ring imaging Cherenkov detector

Author

N Akopov, E.C Aschenauer, K Bailey, S Bernreuther, N Bianchi, G.P Capitani, P Carter, E Cisbani, R De Leo, E De Sanctis, D De Schepper, V Djordjadze, B.W Filippone, S Frullani, F Garibaldi, J.-O Hansen, B Hommez, M Iodice, H.E Jackson, P Jung, R Kaiser, J Kanesaka, R Kowalczyk, L Lagamba, A Maas, V Muccifora, E Nappi, K Negodaeva, W.-D Nowak, T O'Connor, T.G O'Neill, D.H Potterveld, D Ryckbosch, Y Sakemi, F Sato, A Schwind, T.-A Shibata, K Suetsugu, E Thomas, M Tytgat, G.M Urciuoli, K Van de Kerckhove, R Van de Vyver, S Yoneyama, H Zohrabian, and L.F Zhang

Subjects
HERMES experiment, Physics, Nuclear and High Energy Physics, Photomultiplier, Physics - Instrumentation and Detectors, Spectrometer, Physics::Instrumentation and Detectors, business.industry, Detector, FOS: Physical sciences, DESY, Instrumentation and Detectors (physics.ins-det), Particle identification, Optics, Electromagnetic shielding, Radiator (engine cooling), High Energy Physics::Experiment, business, Instrumentation
Abstract

The construction and use of a dual radiator Ring Imaging Cerenkov(RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasizes measurements of semi-inclusive deep-inelastic scattering. It provides particle identification for pions, kaons, and protons in the momentum range from 2 to 15 GeV, which is essential to these studies. The instrument uses two radiators, C4F10, a heavy fluorocarbon gas, and a wall of silica aerogel tiles. The use of aerogel in a RICH detector has only recently become possible with the development of clear, large homogeneous and hydrophobic aerogel. A lightweight mirror was constructed using a newly perfected technique to make resin-coated carbon-fiber surfaces of optical quality. The photon detector consists of 1934 photomultiplier tubes for each detector half, held in a soft steel matrix to provide shielding against the residual field of the main spectrometer magnet., 25 pages, 23 figures

Published
2002

5. The luminosity monitor of the HERMES experiment at DESY

Author

Klaus Rith, Adel Terkulov, S. Bernreuther, Ch. Weiskopf, V. Kozlov, Th. Benisch, E. Devitsin, and S. Potashov

Subjects
HERMES experiment, Physics, Nuclear and High Energy Physics, Electron pair, Photon, Luminosity (scattering theory), Physics::Instrumentation and Detectors, DESY, Electron, Radiation, Calorimeter, Nuclear physics, Physics::Accelerator Physics, High Energy Physics::Experiment, Instrumentation
Abstract

A detector is described which measures the luminosity of the HERMES experiment at DESY. It is based on the coincident detection of electron–positron and photon pairs, or electron pairs, originating from the interaction of the beam positrons, or electrons, with the electrons of the atomic gas target. It consists of two calorimeters with radiation hard NaBi(WO 4 ) 2 crystals. Properties of the monitor, investigated in an electron test beam, and its performance in the experiment are presented.

Published
2001

6. 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

7. Nuclear effects on R=σL/σT in deep-inelastic scattering

Author

K Ackerstaff, A Airapetian, N Akopov, I Akushevich, 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, M Bouwhuis, J Brack, S Brauksiepe, B Braun, B Bray, St Brons, W Brückner, A Brüll, E.E.W Bruins, 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, A Fechtchenko, M Ferstl, K Fiedler, B.W Filippone, H Fischer, B Fox, J Franz, S Frullani, M.-A Funk, Y Gärber, H Gao, 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, V Gyurjyan, J.P Haas, W Haeberli, J.-O Hansen, M Hartig, 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, 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, V.G Krivokhijine, M Kurisuno, G Kyle, W Lachnit, P Lenisa, 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 Menden, A Metz, N Meyners, O Mikloukho, C.A Miller, M.A Miller, R Milner, A Most, V Muccifora, R Mussa, A Nagaitsev, Yu Naryshkin, A.M Nathan, F Neunreither, J.M Niczyporuk, W.-D Nowak, M Nupieri, T.G O'Neill, R Openshaw, 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, P Rossi, S Rudnitsky, M Ruh, D Ryckbosch, Y Sakemi, I Savin, 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, E Thomas, B Tipton, M Tytgat, G.M Urciuoli, J.F.J van den Brand, G van der Steenhoven, R van de Vyver, 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
Physics, HERMES experiment, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, Scattering, Sigma, DESY, Deep inelastic scattering, 01 natural sciences, Nuclear physics, Transverse plane, Cross section (physics), 0103 physical sciences, 010306 general physics, Scaling
Abstract

Cross section ratios for deep-inelastic scattering from 14N and 3He with respect to 2H have been measured by the HERMES experiment at DESY using a 27.5 GeV positron beam. The data cover a range in the Bjorken scaling variable x between 0.013 and 0.65, while the negative squared four-momentum transfer Q^2 varies from 0.5 to 15 GeV^2. The data are compared to measurements performed by NMC, E665, and SLAC on 4He and 12C, and are found to be different for x < 0.06 and Q^2 < 1.5 GeV^2. The observed difference is attributed to an A-dependence of the ratio R = sigma_L / sigma_T of longitudinal to transverse deep-inelastic scattering cross sections at low x and low Q^2.

Published
2000

8. 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

9. Beam-induced nuclear depolarization in a gaseous polarized-hydrogen target

Author

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

Subjects
HERMES experiment, Physics, Hydrogen, General Physics and Astronomy, chemistry.chemical_element, FOS: Physical sciences, DESY, Depolarization, HERA, Magnetic field, High Energy Physics - Experiment, NO, High Energy Physics - Experiment (hep-ex), Bunches, chemistry, Physics::Accelerator Physics, High Energy Physics::Experiment, Atomic physics, Beam (structure)
Abstract

Spin-polarised atomic hydrogen is used as a gaseous polarised proton target in high energy and nuclear physics experiments operating with internal beams in storage rings. When such beams are intense and bunched, this type of target can be depolarised by a resonant interaction with the transient magnetic field generated by the beam bunches. This effect has been studied with the HERA positron beam in the HERMES experiment at DESY. Resonances have been observed and a simple analytic model has been used to explain their shape and position. Operating conditions for the experiment have been found where there is no significant target depolarisation due to this effect., REVTEX, 6 pages, 5 figures

Published
1999

10. 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

11. 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

12. Measurement of the neutron spin structure function g with a polarized 3He internal target

Author

K. Ackerstaff, A. Airapetian, I. Akushevich, N. Akopov, M. Amarian, E.C. Aschenauer, R. Avakian, H. Avakian, A. Avetissian, B. Bains, S. Barrow, M. Beckmann, S. Belostotski, J.E. Belz, Th. Benisch, S. Bernreuther, N. Bianchi, S. Blanchard, J. Blouw, H. Böttcher, A. Borissov, J. Brack, B. Braun, B. Bray, W. Brückner, A. Brüll, E.E.W. Bruins, H.J. Bulten, G.P. Capitani, P. Carter, E. Cisbani, G.R. Court, P.P.J. Delheij, E. Devitsin, C.W. de Jager, E. De Sanctis, D. De Schepper, P.K.A. de Witt Huberts, 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, P. Geiger, V. Gharibyan, A. Golendoukhin, G. Graw, O. Grebeniouk, P.W. Green, L.G. Greeniaus, C. Grosshauser, A. Gute, V. Gyurjyan, J.P. Haas, W. Haeberli, J.-O. Hansen, D. Hasch, O. Häusser, R.S. Henderson, Th. Henkes, R. Hertenberger, Y. Holler, R.J. Holt, H. Ihssen, M. Iodice, A. Izotov, H.E. Jackson, A. Jgoun, C. Jones, R. Kaiser, E. Kinney, M. Kirsch, A. Kisselev, P. Kitching, N. Koch, K. Königsmann, M. Kolstein, H. Kolster, W. Korsch, V. Kozlov, L.H. Kramer, B. Krause, V.G. Krivokhijine, M. Kückes, G. Kyle, W. Lachnit, W. Lorenzon, A. Lung, N.C.R. Makins, S.I. Manaenkov, F.K. Martens, J.W. Martin, A. Mateos, K. McIlhany, R.D. McKeown, F. Meissner, 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, V. Papavassiliou, S.F. Pate, M. Pitt, S. Potashov, D.H. Potterveld, B. Povh, G. Rakness, R. Redwine, A.R. Reolon, R. Ristinen, K. Rith, G. Röper, H. Roloff, P. Rossi, S. Rudnitsky, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, K.P. Schüller, A. Schwind, T.-A. Shibata, T. Shin, A. Simon, K. Sinram, 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, B. Tipton, A. Trudel, M. Tytgat, G.M. Urciuoli, R. Van de Vyver, J.F.J. van den Brand, G. van der Steenhoven, M.C. Vetterli, E. Volk, W. Wander, T.P. Welch, S.E. Williamson, T. Wise, T. Wölfel, K. Zapfe-Düren, H. Zohrabian, and R. Zurmühle

Subjects
Physics, HERMES experiment, Nuclear and High Energy Physics, Range (particle radiation), 010308 nuclear & particles physics, Astrophysics::Cosmology and Extragalactic Astrophysics, HERA, Spin structure, Deep inelastic scattering, 01 natural sciences, Nuclear physics, Positron, 0103 physical sciences, High Energy Physics::Experiment, Neutron, Atomic physics, 010306 general physics, Spin-½
Abstract

Results are reported from the HERMES experiment at HERA on a measurement of the neutron spin structure function g1n(x, Q2) in deep inelastic scattering using 27.5 GeV longitudinally polarized positrons incident on a polarized 3He internal gas target. The data cover the kinematic range 0.023

Published
1997

13. Design and performance of the large HERMES drift chambers

Author

U Harder, B. Krause, A. Schwind, M. Ferstl, H Russo, H. Böttcher, F. Schmidt, M. Kirsch, S. Bernreuther, W. Lachnit, F. Meißner, F. Neunreither, A. Borissov, M Pohl, A. Gute, A. Miller, W.-D. Nowak, W. Brückner, D Hasch, and H.O. Roloff

Subjects
Physics, Nuclear and High Energy Physics, Planar, Optics, Downstream (manufacturing), Spectrometer, business.industry, Plane (geometry), Tracking system, business, Instrumentation
Abstract

Big planar drift chambers built for the downstream tracking system of the HERMES spectrometer are described. Using the fast non-flammable gas mixture Ar/CO 2 /CF 4 (90/5/5) average spatial resolutions of about 180 μm per plane at efficiencies above 96% have been obtained from test run data analysis.

Published
1995

14. Transverse polarization ofΛandΛ¯hyperons in quasireal photoproduction

Author

I. Brunn, A. Kisselev, J. Wilbert, W. Augustyniak, Alessandra Fantoni, G. Graw, B. D. Fox, B. Zihlmann, M. Stancari, V. Mexner, B. Tchuiko, M. Kopytin, A. Nass, G. Schnell, O. Grebeniouk, A. Nagaitsev, B. Hommez, P. E. Reimer, P. Lenisa, J. Seibert, A. Trzcinski, Michel Vetterli, M. Henoch, E. Thomas, A. Laziev, M. Vogt, D. Reggiani, N. Akopov, B. Seitz, S. Tessarin, P. B. van der Nat, Katerina Lipka, K. Oganessyan, G. Iarygin, F. Masoli, J. Visser, A. Jgoun, V. A. Gapienko, G. M. Urciuoli, H. Kolster, Dirk Ryckbosch, M. Amarian, V. Vikhrov, Adel Terkulov, R. Van de Vyver, S. Belostotski, Manuella Vincter, H. Marukyan, Hidekazu Tanaka, M. Statera, Rezo Shanidze, J. Franz, Salvatore Frullani, Y. Gärber, J. Stewart, L. G. Greeniaus, V. A. Korotkov, A. Brüll, F. Menden, P. F. Dalpiaz, V. V. Ammosov, S. Yen, H. E. Jackson, A. Tkabladze, V. G. Krivokhijine, Andrey V. Izotov, C. Weiskopf, Ralf Kaiser, H. P. Blok, H. C. Chiang, C. Baumgarten, Ralf Hertenberger, S. Yoneyama, C. A. Miller, Valeria Muccifora, E. Steffens, G. Gavrilov, B. Krauss, C. Scarlett, Wolfgang Lorenzon, J. Ely, K. Königsmann, V. Baturin, V. A. Kozlov, M. Ehrenfried, S. Potashov, E. De Sanctis, Franco Garibaldi, H. Zohrabian, W.H.A. Hesselink, R. De Leo, A. Fechtchenko, D. Veretennikov, G. Elbakian, Erika Garutti, S. Bernreuther, M. Bouwhuis, A. Airapetian, H. Böttcher, Michael Tytgat, A. Andrus, S. Taroian, A. Elalaoui-Moulay, Frank Ellinghaus, A. Borissov, P. Di Nezza, P. Liebing, E. R. Kinney, M. Contalbrigo, A. Schwind, Martin Raithel, E. C. Aschenauer, Y. Naryshkin, L. Felawka, V. Shutov, U. Elschenbroich, I. Sanjiev, G. Orlandi, K. P. Schüler, Naomi C R Makins, D. Gaskell, A. Hillenbrand, G. P. Capitani, E. Avetissian, Nicola Bianchi, O. Mikloukho, P. Bailey, U. Stosslein, L. Lagamba, Z. Akopov, Y. Miyachi, P. Zupranski, J. Wendland, D. Hasch, D. H. Potterveld, R. Fabbri, T. A. Shibata, G. Gapienko, R.O. Avakian, N. Meyners, G. Rosner, E. Devitsin, K. Sinram, H. Ohsuga, L. De Nardo, V. Gharibyan, A. Rostomyan, A. R. Reolon, A. Avetissian, J. Volmer, J. J. M. Steijger, Michael Düren, K. Hafidi, Y. Holler, M. C. Simani, A. Reischl, G. Ciullo, Christian Schill, Eugenio Nappi, M. Hartig, T. Wise, M. Beckmann, L. Lapikás, Jeffrey Brack, W. Haeberli, Klaus Rith, D. Heesbeen, G. van der Steenhoven, T. Lindemann, I.A. Savin, G.R. Court, Andreas Schäfer, and W.-D. Nowak

Subjects
Physics, HERMES experiment, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Hyperon, Lambda, Lambda baryon, Polarization (waves), 01 natural sciences, Particle identification, Nuclear physics, Transverse plane, Light cone, 0103 physical sciences, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment, 010306 general physics
Abstract

The HERMES experiment has measured the transverse polarization of Lambda and {ovr Lambda} hyperons produced inclusively in quasireal photoproduction at a positron beam energy of 27.6 GeV. The transverse polarization P{sub n}{sup Lambda} of the Lambda hyperon is found to be positive while the observed {ovr Lambda} polarization is compatible with zero. The values averaged over the kinematic acceptance of HERMES are P{sub n}{sup Lambda} =0.078 {+-} 0.006(stat) {+-} 0.012(syst) and P{sub n}{sup {ovr Lambda}} = -0.025 {+-} 0.015(stat) {+-} 0.018(syst) for Lambda and {ovr Lambda}, respectively. The dependences of P{sub n}{sup Lambda} and P{sub n}{sup {ovr Lambda}} on the fraction zeta of the beam's light-cone momentum carried by the hyperon and on the hyperon's transverse momentum p{sub T} were investigated. The measured Lambda polarization rises linearly with p{sub T} and exhibits a different behavior for low and high values of zeta, which approximately correspond to the backward and forward regions in the center-of-mass frame of the gamma*N reaction.

Published
2007

15. Measurement of the tensor structure function b1 of the deuteron

Author

M. Vogt, H. Ohsuga, G. Gapienko, M. C. Simani, A. Rostomyan, A. R. Reolon, A. Avetissian, A. Tkabladze, B. D. Fox, G. Schnell, P. E. Reimer, M. Henoch, K. Oganessyan, Hidekazu Tanaka, H. E. Jackson, V. G. Krivokhijine, Gharibyan, T. A. Shibata, R.O. Avakian, E. Devitsin, W. Augustyniak, Erika Garutti, M. Stancari, U. Stosslein, L. Lagamba, Z. Akopov, J. Seele, S. Bernreuther, Shutov, Korotkov, A. Brull, B. Seitz, B. Hommez, J. Wilbert, Arne Vandenbroucke, Riccardo Fabbri, Di Nezza P, Muccifora, Michael Tytgat, M. Demey, Gapienko, I. M. Gregor, Alessandra Fantoni, M. Hoek, Y. Holler, S. Taroian, G. Graw, A. Andrus, W.-D. Nowak, Klaus Rith, D. Heesbeen, Mexner, G. Iarygin, B. Tchuiko, M. Kopytin, M. Negodaev, A. Nass, P. Bailey, U. Elschenbroich, H. Marukyan, A. Airapetian, A. Kisselev, L. Felawka, M. Amarian, A. Borissov, De Leo R, G. P. Capitani, M. Bouwhuis, L. G. Greeniaus, F. Stinzing, K. Hafidi, A. Laziev, H. Böttcher, B. Maiheu, C. Weiskopf, D. Reggiani, A. Jgoun, I.A. Savin, A. Hillenbrand, A. Fechtchenko, Y. X. Ye, P. Zupranski, P. Lenisa, A. Trzcinski, J. Dreschler, A. Elalaoui-Moulay, Frank Ellinghaus, B. Marianski, J. Volmer, A. Ivanilov, P. F. Dalpiaz, E. R. Kinney, N. Meyners, P. Tait, G. Rosner, V. V. Ammosov, F. Garibaldi, K. P. Schüler, De Sanctis E, K. Garrow, Y. Salomatin, H. P. Blok, E. Avetissian, B. Zihlmann, D. Balin, Nicola Bianchi, Y. Naryshkin, O. Mikloukho, Ralf Hertenberger, Wolfgang Lorenzon, J. G. Rubin, Hasko Stenzel, A. Reischl, B. Q. Ma, H. C. Chiang, M. Ehrenfried, G. Ciullo, Christian Schill, Bryzgalov, Houbing Lu, Eugenio Nappi, S. Potashov, L. Rubacek, D. H. Potterveld, Y. J. Mao, R. Seidl, M. Contalbrigo, Manuella Vincter, Martin Raithel, E. C. Aschenauer, De Nardo L, van der Steenhoven G, S. Belostotski, Kozlov, M. Hartig, I. Sanjiev, Naomi C R Makins, J. Stewart, S. Frullani, O. Grebeniouk, C. Riedl, P. Liebing, J. Lu, M. Beckmann, S. Yen, C. A. Miller, Ralf Kaiser, E. Steffens, G. Gavrilov, Vikhrov, Baturin, B. Krauss, L. A. Linden-Levy, N. Pickert, Dirk Ryckbosch, van der Nat Pb, S. Lu, M. Statera, Adel Terkulov, Andrey V. Izotov, D. Gaskell, L. Lapikás, Jeffrey Brack, Katerina Lipka, C. Vogel, G. Elbakian, J. J. M. Steijger, Michael Düren, Y. Miyachi, J. Wendland, D. Hasch, K. Sinram, Zhenyu Ye, C. Shearer, T. Chen, A. Nagaitsev, Michel Vetterli, N. Akopov, F. Masoli, Rezo Shanidze, Andreas Schäfer, W.H.A. Hesselink, A. Borysenko, (Astro)-Particles Physics, and Photo Conversion Materials

Subjects
HERMES experiment, Particle physics, media_common.quotation_subject, FOS: Physical sciences, General Physics and Astronomy, Spin structure, Inelastic scattering, Asymmetry, High Energy Physics - Experiment, 14.65.−q, Nuclear physics, High Energy Physics - Experiment (hep-ex), 13.88.+e, SDG 7 - Affordable and Clean Energy, Nuclear Experiment, media_common, Physics, 13.60.−r, 14.20.Dh, Scattering, Momentum transfer, HERA, Deep inelastic scattering, High Energy Physics::Experiment
Abstract

The \Hermes experiment has investigated the tensor spin structure of the deuteron using the 27.6 GeV/c positron beam of \Hera. The use of a tensor polarized deuteron gas target with only a negligible residual vector polarization enabled the first measurement of the tensor asymmetry $\At$ and the tensor structure function $\bd$ for average values of the Bj��rken variable $0.01<< x>

Published
2005

16. Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering

Author

P. Zupranski, N. Meyners, G. Rosner, A. Airapetian, A. Borissov, Hidekazu Tanaka, A. Nagaitsev, A. Tkabladze, M. Negodaev, M. Contalbrigo, B. Hommez, Salvatore Frullani, P. E. Reimer, R. Seidl, C. Shearer, V. A. Korotkov, M. Bouwhuis, Martin Raithel, E. C. Aschenauer, V. Shutov, A. Hillenbrand, G. Graw, M. Henoch, V. A. Kozlov, I. Sanjiev, H. Ohsuga, Michel Vetterli, B. D. Fox, B. Zihlmann, H. C. Chiang, S. Belostotski, J. Volmer, H. P. Blok, Erika Garutti, H. Böttcher, A. Ivanilov, B. Seitz, M. Statera, V. A. Gapienko, G. Orlandi, V. Bryzgalov, Wolfgang Lorenzon, Naomi C R Makins, G. Schnell, P. F. Dalpiaz, M. Stancari, D. Gaskell, N. Akopov, K. Königsmann, V. Baturin, U. Elschenbroich, L. Felawka, M. Amarian, A. Fechtchenko, Ralf Hertenberger, E. De Sanctis, V. Gharibyan, Franco Garibaldi, G. Iarygin, G. Elbakian, K. P. Schüler, Y. Holler, S. Bernreuther, Andrey V. Izotov, A. Elalaoui-Moulay, Frank Ellinghaus, P. B. van der Nat, E. R. Kinney, P. Bailey, P. Tait, G. P. Capitani, A. Schwind, Dirk Ryckbosch, Valeria Muccifora, W.H.A. Hesselink, H. Marukyan, E. Avetissian, Nicola Bianchi, O. Mikloukho, A. Rostomyan, A. R. Reolon, Y. Naryshkin, J. Franz, Michael Tytgat, S. Potashov, O. Grebeniouk, H. Zohrabian, U. Stosslein, L. Lagamba, M. C. Simani, A. Avetissian, Z. Akopov, F. Masoli, J. Visser, M. Vogt, V. Vikhrov, Manuella Vincter, J. Lu, S. Taroian, S. Yen, G. V. Ybeles Smit, C. A. Miller, L. G. Greeniaus, C. Weiskopf, A. Andrus, Katerina Lipka, H. E. Jackson, Ralf Kaiser, J. Seele, B. Krauss, V. G. Krivokhijine, P. Di Nezza, Alessandra Fantoni, J. Ely, A. Reischl, Y. Miyachi, L. Rubacek, M. Hoek, A. Jgoun, C. Scarlett, K. Hafidi, E. Steffens, P. Liebing, C. Baumgarten, G. Gapienko, G. Gavrilov, P. Lenisa, G. Ciullo, C. Vogel, C. Riedl, R. Fabbri, T. A. Shibata, K. Oganessyan, J. Wendland, Christian Schill, R.O. Avakian, A. Trzcinski, Adel Terkulov, B. Tchuiko, M. Kopytin, D. Hasch, A. Nass, D. Reggiani, V. Mexner, L. Lapikás, E. Devitsin, J. Stewart, V. V. Ammosov, A. Brüll, J. Wilbert, Y. Gärber, D. H. Potterveld, Y. Salomatin, Arne Vandenbroucke, R. Shanidze, M. Hartig, A. Laziev, W. Augustyniak, N. Pickert, M. Ehrenfried, K. Garrow, R. De Leo, B. Marianski, Jeffrey Brack, W.-D. Nowak, Eugenio Nappi, A. Kisselev, B. Maiheu, M. Beckmann, K. Sinram, L. De Nardo, J. J. M. Steijger, Michael Düren, G. van der Steenhoven, T. Lindemann, Klaus Rith, D. Heesbeen, I.A. Savin, Andreas Schäfer, (Astro)-Particles Physics, Photo Conversion Materials, and Student Lab and Education

Subjects
Quark, Particle physics, Meson, High Energy Physics::Lattice, Nuclear Theory, Hadron, FOS: Physical sciences, General Physics and Astronomy, 13.60.–r, Inelastic scattering, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Pion, 13.88.+e, Nuclear Experiment, 14.20.Dh, 14.65.–q, QC, Physics, High Energy Physics::Phenomenology, Quark model, Deep inelastic scattering, Baryon, High Energy Physics::Experiment
Abstract

Double-spin asymmetries of semi-inclusive cross sections for the production of identified pions and kaons have been measured in deep-inelastic scattering of polarized positrons on a polarized deuterium target. Five helicity distributions including those for three sea quark flavors were extracted from these data together with re-analyzed previous data for identified pions from a hydrogen target. These distributions are consistent with zero for all three sea flavors. A recently predicted flavor asymmetry in the polarization of the light quark sea appears to be disfavored by the data., Comment: 5 pages, 3 figures

Published
2004

17. Evidence for a narrow |S|=1 baryon state at a mass of 1528 MeV in quasi-real photoproduction

Author

J. Stewart, A. Brüll, Ralf Hertenberger, W.H.A. Hesselink, J. Lu, S. Yen, K. Garrow, Y. Salomatin, Z. Ye, L. A. Linden-Levy, C. A. Miller, B. Hommez, Wouter Deconinck, C. Shearer, Ralf Kaiser, P. Zupranski, A. Elalaoui-Moulay, Frank Ellinghaus, E. Steffens, A. Jgoun, Ingrid-Maria Gregor, H. P. Blok, W. Augustyniak, G. Ciullo, E. R. Kinney, G. Gavrilov, U. Elschenbroich, B. Marianski, Wolfgang Lorenzon, J. Ely, V. Mexner, N. Meyners, G. Rosner, M. Ehrenfried, R. De Leo, A. Fantoni, A. Tkabladze, P. B. van der Nat, H. Y. Lu, M. Contalbrigo, B. D. Fox, Y. Naryshkin, Dirk Ryckbosch, B. Zihlmann, K. P. Schüler, Jeffrey Brack, Katerina Lipka, Martin Raithel, W.-D. Nowak, C. Riedl, T. Chen, E. C. Aschenauer, G. Schnell, P.F. Dalpiaz, V. Shutov, M. Vogt, I. Sanjiev, K. Hafidi, M. Statera, Hasko Stenzel, A. Kisselev, H. E. Jackson, Michael Tytgat, Naomi C R Makins, F. Masoli, E. Nappi, A. Nagaitsev, D. Gaskell, A. Airapetian, D. Balin, O. Mikloukho, A. Hillenbrand, G. Iarygin, S. Belostotski, E. De Sanctis, V. Gharibyan, V. Bryzgalov, V. G. Krivokhijine, S. Potashov, K. Oganessyan, J. Wilbert, H. Zohrabian, F. Garibaldi, A. Fechtchenko, Michel Vetterli, R. Seidl, A. Borissov, Arne Vandenbroucke, G. Graw, S. Taroian, M. Bouwhuis, H. Böttcher, P. Lenisa, A. R. Reolon, A. Laziev, Riccardo Fabbri, V. A. Gapienko, C. Vogel, A. Andrus, A. Trzcinski, D. Reggiani, F. Stinzing, N. Akopov, N. Bianchi, V. V. Ammosov, H. Marukyan, R. Shanidze, Y. X. Ye, P. E. Reimer, P. Tait, M. Negodaev, S. Frullani, X. R. Lu, Bo-Qiang Ma, V. Kozlov, L. Lapikás, B. Krauss, V. Muccifora, P. Liebing, Erika Garutti, U. Stosslein, M. Hoek, M. Henoch, T. A. Shibata, E. Avetissian, V. A. Korotkov, J. G. Rubin, N. Pickert, R.O. Avakian, Xun Chen, J. Seele, S. Bernreuther, O. Grebeniouk, Z. Akopov, E. Devitsin, B. Tchuiko, M. Kopytin, S. Lu, Hidekazu Tanaka, A. Nass, Adel Terkulov, V. Baturin, V. Vikhrov, Manuella Vincter, H. C. Chiang, G. Elbakian, P. Bailey, Andrey V. Izotov, G.P. Capitani, D. Hasch, B. Maiheu, Y. Mao, G. V. Ybeles Smit, L. G. Greeniaus, B. Seitz, C. Weiskopf, L. Felawka, M. Amarian, L. Lagamba, P. Di Nezza, G. Gapienko, M. C. Simani, Y. Miyachi, J. Wendland, D. H. Potterveld, H. Ohsuga, A. Rostomyan, A. Avetissian, K. Sinram, L. De Nardo, J. J. M. Steijger, Michael Düren, M. Stancari, A. Reischl, C. Schill, M. Beckmann, J. Volmer, A. Ivanilov, Y. Holler, G. van der Steenhoven, M. Hartig, A. Borysenko, W. Yu, I.A. Savin, Andreas Schäfer, Klaus Rith, D. Heesbeen, and L. Rubacek

Subjects
Nuclear and High Energy Physics, Particle physics, Nuclear Theory, FOS: Physical sciences, 01 natural sciences, NO, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), 0103 physical sciences, Invariant mass, 12.39.Mk, 13.60.-r, 13.60.Rj, 14.20.-c, 010306 general physics, Nuclear Experiment, Physics, Isovector, 010308 nuclear & particles physics, State (functional analysis), Pentaquark, Baryon, Deuterium, Exotic baryon, Mass spectrum, High Energy Physics::Experiment
Abstract

Evidence for a narrow baryon state is found in quasi-real photoproduction on a deuterium target through the decay channel p K^0_S --> p pi^+ pi^-. A peak is observed in the p K^0_S invariant mass spectrum at 1528 +/- 2.6 (stat) +/-2.1 (syst) MeV. Depending on the background model,the naive statistical significance of the peak is 4--6 standard deviations and its width may be somewhat larger than the experimental resolution of sigma=4.3 -- 6.2 MeV. This state may be interpreted as the predicted S=+1 exotic Theta^{+}(uuddbar(s)) pentaquark baryon. No signal for an hypothetical Theta^{++} baryon was observed in the pK^+ invariant mass distribution. The absence of such a signal indicates that an isotensor Theta is excluded and an isovector Theta is unlikely., 8 pages, 4 figures

Published
2003

18. Q2Dependence of Nuclear Transparency for Exclusiveρ0Production

Author

I. Brunn, A. Kisselev, J. Wilbert, A. Nagaitsev, U. Stosslein, L. Lagamba, Z. Akopov, V. A. Korotkov, Michel Vetterli, A. Laziev, V. Gapienko, P. E. Reimer, M. Henoch, B. D. Fox, B. Zihlmann, Y. Miyachi, M. Stancari, T. Wise, J. Wendland, W. Augustyniak, G. van der Steenhoven, N. Akopov, G. Schnell, D. Hasch, K. Königsmann, V. Baturin, B. Hommez, M. Beckmann, D. H. Potterveld, H. P. Blok, Alessandra Fantoni, S. Tessarin, S. Yoneyama, T. Lindemann, K. Hafidi, H. Kolster, H. Ohsuga, G. Elbakian, G. Graw, Wolfgang Lorenzon, S. Bernreuther, A. Tkabladze, A. Elalaoui-Moulay, Frank Ellinghaus, Dirk Ryckbosch, R. Fabbri, B. Tchuiko, M. Kopytin, T. A. Shibata, A. Nass, S. Podiatchev, A. Rostomyan, R.O. Avakian, E. R. Kinney, A. R. Reolon, A. Avetissian, A. Jgoun, B. Seitz, A. Schwind, P. Lenisa, J. Seibert, K. Sinram, E. Devitsin, L. De Nardo, A. Trzcinski, G. Gapienko, O. Grebeniouk, P. B. van der Nat, D. Reggiani, M. Vogt, Y. Naryshkin, V. Gharibyan, V. V. Ammosov, K. Oganessyan, M. Ehrenfried, A. Hillenbrand, E. De Sanctis, V. Vikhrov, Manuella Vincter, Franco Garibaldi, R. De Leo, V. A. Kozlov, Klaus Rith, D. Heesbeen, M. Bouwhuis, J. J. M. Steijger, Michael Düren, L. G. Greeniaus, C. Weiskopf, H. Böttcher, H. E. Jackson, S. Belostotski, V. G. Krivokhijine, Eugenio Nappi, Erika Garutti, C. Baumgarten, A. Andrus, G. Iarygin, L. Felawka, I.A. Savin, B. Krauss, G. P. Capitani, H. Marukyan, R. Van de Vyver, C. Scarlett, G.R. Court, J. Franz, Andreas Schäfer, A. Terkulov, K. Negodaeva, M. Amarian, M. Hartig, S. Potashov, H. Zohrabian, Hidekazu Tanaka, U. Elschenbroich, A. Airapetian, P. Bailey, G. M. Urciuoli, P. Di Nezza, J. Stewart, P. Liebing, A. Brüll, Ralf Hertenberger, W.H.A. Hesselink, P. Zupranski, H. C. Chiang, N. Meyners, G. Rosner, L. Lapikás, K. P. Schüler, A. Borissov, E. Avetissian, Nicola Bianchi, O. Mikloukho, A. Reischl, W. Haeberli, G. Ciullo, Christian Schill, Salvatore Frullani, Valeria Muccifora, P. F. Dalpiaz, Y. Holler, Jeffrey Brack, M. C. Simani, J. Volmer, A. Fechtchenko, Michael Tytgat, S. Taroian, Y. Gärber, E. Thomas, R. Shanidze, M. Contalbrigo, Martin Raithel, E. C. Aschenauer, V. Shutov, M. Statera, I. Sanjiev, Andrey V. Izotov, G. Orlandi, Naomi C R Makins, C. A. Miller, J. Ely, D. Gaskell, F. Menden, S. Yen, Ralf Kaiser, E. Steffens, G. Gavrilov, F. Masoli, J. Visser, V. Mexner, and W.-D. Nowak

Subjects
HERMES experiment, Physics, Nuclear reaction, Particle physics, Meson, Nuclear Theory, Hadron, General Physics and Astronomy, Virtual particle, Coherence length, Nuclear physics, Nuclear transparency, High Energy Physics::Experiment, Nuclear Experiment, Nucleon
Abstract

Exclusive coherent and incoherent electroproduction of the rho(0) meson from H-1 and N-14 targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (-Q(2)). The ratio of N-14 to H-1 cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing l(c) for coherent (incoherent) rho(0) electroproduction. For fixed l(c), a rise of nuclear transparency with Q(2) is observed for both coherent and incoherent rho(0) production, which is in agreement with theoretical calculations of color transparency.

Published
2003

19. Quark fragmentation to π±, π0, K±, p and p_bar in the nuclear environment

Author

R. Fabbri, Katerina Lipka, A. Fechtchenko, T. A. Shibata, M. Statera, K. P. Schüler, R.O. Avakian, E. Nappi, Dirk Ryckbosch, C. Shearer, C. Vogel, B. Seitz, E. Devitsin, O. Mikloukho, A. R. Reolon, J. Seele, S. Bernreuther, J. Wilbert, L. Lapikás, U. Elschenbroich, P. B. van der Nat, Adel Terkulov, Arne Vandenbroucke, H. E. Jackson, V. G. Krivokhijine, G. Gapienko, S. Belostotski, V. Bryzgalov, Y. Salomatin, W. Augustyniak, A. Tkabladze, F. Garibaldi, C. Baumgarten, Ralf Hertenberger, E. Avetissian, H. C. Chiang, B. D. Fox, Y. Holler, V. A. Korotkov, K. Sinram, L. De Nardo, G. Schnell, M. C. Simani, M. Stancari, M. Contalbrigo, V. Vikhrov, W.H.A. Hesselink, S. Potashov, P. E. Reimer, H. Zohrabian, Martin Raithel, Manuella Vincter, E. C. Aschenauer, V. Shutov, M. Henoch, Jeffrey Brack, H. Tanaka, K. Königsmann, B. Krauss, M. Hoek, V. Baturin, I. Sanjiev, A. Airapetian, Hasko Stenzel, C. Scarlett, V. Gharibyan, G. Graw, M. Ehrenfried, Naomi C R Makins, D. Gaskell, R. De Leo, P. Liebing, K. Hafidi, G. Elbakian, A. Borissov, L. Rubacek, M. Vogt, B. Tchuiko, M. Kopytin, J. Lu, A. Nass, B. Hommez, S. Yen, A. Elalaoui-Moulay, Frank Ellinghaus, E. R. Kinney, G. V. Ybeles Smit, R. Seidl, E. Garutti, A. Hillenbrand, V. Mexner, A. Schwind, Ralf Kaiser, Y. Naryshkin, B. Marianski, Andrey V. Izotov, E. De Sanctis, M. Bouwhuis, H. Ohsuga, H. Böttcher, E. Steffens, J. Stewart, A. Brüll, G. Gavrilov, D. Hasch, Y. Miyachi, J. Wendland, K. Oganessyan, A. Laziev, W.-D. Nowak, Michael Tytgat, A. Ivanilov, L. Felawka, V. Gapienko, B. Maiheu, P. Tait, D. H. Potterveld, M. Amarian, C. A. Miller, K. Garrow, J. Ely, A. Rostomyan, A. Avetissian, A. Kisselev, L. Lagamba, A. Fantoni, A. Reischl, S. Taroian, N. Bianchi, A. Nagaitsev, J. J. M. Steijger, Michael Düren, P. Di Nezza, G. Iarygin, Michel Vetterli, G. Ciullo, Christian Schill, H. Marukyan, J. Franz, B. Zihlmann, R. Shanidze, V. Kozlov, S. Frullani, N. Pickert, N. Akopov, O. Grebeniouk, P. F. Dalpiaz, G.P. Capitani, H. P. Blok, P. Zupranski, Wolfgang Lorenzon, V. V. Ammosov, J. Volmer, F. Masoli, N. Meyners, G. Rosner, U. Stosslein, Z. Akopov, G. van der Steenhoven, T. Lindemann, L. G. Greeniaus, C. Weiskopf, A. Borysenko, Klaus Rith, D. Heesbeen, I.A. Savin, Andreas Schäfer, P. Lenisa, A. Trzcinski, D. Reggiani, V. Muccifora, M. Hartig, M. Negodaev, P. Bailey, I. M. Gregor, A. Jgoun, C. Riedl, M. Beckmann, and A. Andrus

Subjects
HERMES experiment, Quark, Nuclear and High Energy Physics, Meson, Nuclear Theory, Hadron, chemistry.chemical_element, 13.87.Fh, 13.60.-r, 14.20.-c, 14.40.-n, 01 natural sciences, 7. Clean energy, Nuclear physics, 0103 physical sciences, Multiplicity (chemistry), Nuclear Experiment, 010306 general physics, Physics, 010308 nuclear & particles physics, Krypton, Baryon, Deuterium, chemistry, High Energy Physics::Experiment, Atomic physics
Abstract

The influence of the nuclear medium on lepto-production of hadrons was studied in the HERMES experiment at DESY in semi-inclusive deep-inelastic scattering of 27.6 GeV positrons off deuterium, nitrogen and krypton targets. The differential multiplicity for krypton relative to that of deuterium has been measured for the first time for various identified hadrons (π+, π−, π0, K+, K−, p and p ) as a function of the virtual photon energy ν, the fraction z of this energy transferred to the hadron, and the hadron transverse momentum squared pt2. The multiplicity ratio is strongly reduced in the nuclear medium at low ν and high z, with significant differences among the various hadrons. The distribution of the hadron transverse momentum is broadened towards high pt2 in the nuclear medium, in a manner resembling the Cronin effect previously observed in collisions of heavy ions and protons with nuclei.

Published
2003

20. Q2 dependence of nuclear transparency for exclusive rho0 production

Author

A, Airapetian, N, Akopov, Z, Akopov, M, Amarian, V V, Ammosov, A, Andrus, E C, Aschenauer, W, Augustyniak, R, Avakian, A, Avetissian, E, Avetissian, P, Bailey, V, Baturin, C, Baumgarten, M, Beckmann, S, Belostotski, S, Bernreuther, N, Bianchi, H P, Blok, H, Böttcher, A, Borissov, M, Bouwhuis, J, Brack, A, Brüll, I, Brunn, G P, Capitani, H C, Chiang, G, Ciullo, M, Contalbrigo, G R, Court, P F, Dalpiaz, R, De Leo, L, De Nardo, E, De Sanctis, E, Devitsin, P, Di Nezza, M, Düren, M, Ehrenfried, A, Elalaoui-Moulay, G, Elbakian, F, Ellinghaus, U, Elschenbroich, J, Ely, R, Fabbri, A, Fantoni, A, Fechtchenko, L, Felawka, B, Fox, J, Franz, S, Frullani, Y, Gärber, G, Gapienko, V, Gapienko, F, Garibaldi, E, Garutti, D, Gaskell, G, Gavrilov, V, Gharibyan, G, Graw, O, Grebeniouk, L G, Greeniaus, W, Haeberli, K, Hafidi, M, Hartig, D, Hasch, D, Heesbeen, M, Henoch, R, Hertenberger, W H A, Hesselink, A, Hillenbrand, Y, Holler, B, Hommez, G, Iarygin, A, Izotov, H E, Jackson, A, Jgoun, R, Kaiser, E, Kinney, A, Kisselev, K, Königsmann, H, Kolster, M, Kopytin, V, Korotkov, V, Kozlov, B, Krauss, V G, Krivokhijine, L, Lagamba, L, Lapikás, A, Laziev, P, Lenisa, P, Liebing, T, Lindemann, W, Lorenzon, N C R, Makins, H, Marukyan, F, Masoli, F, Menden, V, Mexner, N, Meyners, O, Mikloukho, C A, Miller, Y, Miyachi, V, Muccifora, A, Nagaitsev, E, Nappi, Y, Naryshkin, A, Nass, K, Negodaeva, W-D, Nowak, K, Oganessyan, H, Ohsuga, G, Orlandi, S, Podiatchev, S, Potashov, D H, Potterveld, M, Raithel, D, Reggiani, P, Reimer, A, Reischl, A R, Reolon, K, Rith, G, Rosner, A, Rostomyan, D, Ryckbosch, I, Sanjiev, I, Savin, C, Scarlett, A, Schäfer, C, Schill, G, Schnell, K P, Schüler, A, Schwind, J, Seibert, B, Seitz, R, Shanidze, T-A, Shibata, V, Shutov, M C, Simani, K, Sinram, M, Stancari, M, Statera, E, Steffens, J J M, Steijger, J, Stewart, U, Stösslein, H, Tanaka, S, Taroian, B, Tchuiko, A, Terkulov, S, Tessarin, E, Thomas, A, Tkabladze, A, Trzcinski, M, Tytgat, G M, Urciuoli, P, Van Der Nat, G, Van Der Steenhoven, R, Van De Vyver, M C, Vetterli, V, Vikhrov, M G, Vincter, J, Visser, M, Vogt, J, Volmer, C, Weiskopf, J, Wendland, J, Wilbert, T, Wise, S, Yen, S, Yoneyama, B, Zihlmann, H, Zohrabian, and P, Zupranski

Abstract

Exclusive coherent and incoherent electroproduction of the rho(0) meson from 1H and 14N targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (-Q2). The ratio of 14N to 1H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing l(c) for coherent (incoherent) rho(0) electroproduction. For fixed l(c), a rise of nuclear transparency with Q2 is observed for both coherent and incoherent rho(0) production, which is in agreement with theoretical calculations of color transparency.

Published
2002

21. Evidence for Quark-Hadron Duality in the Proton Spin Asymmetry $A_1$

Author

Michel Vetterli, N. Akopov, F. Menden, B. Hommez, Klaus Rith, D. Heesbeen, L. G. Greeniaus, E. De Sanctis, U. Stosslein, Franco Garibaldi, C. A. Miller, S. Yen, C. Weiskopf, L. Lagamba, A. Jgoun, B. D. Fox, B. Zihlmann, Z. Akopov, J. Ely, Ralf Kaiser, G. Schnell, A. Rostomyan, A. R. Reolon, A. Avetissian, G. M. Urciuoli, J. Stewart, E. Steffens, E. Kotik, A. Brüll, G. Hofman, W. Haeberli, G. Gavrilov, V. V. Ammosov, F. Masoli, J. Visser, F. Sato, A. Reischl, K. Negodaeva, A. Fechtchenko, G. S. Kyle, I.A. Savin, K. Sinram, H. J. Bulten, L. De Nardo, B. Tipton, K. P. Schüler, U. Elschenbroich, M. Amarian, R. Van de Vyver, G. Ciullo, H. P. Blok, S. Yoneyama, Evaristo Cisbani, Valeria Muccifora, V. Gharibyan, L. Felawka, G. Iarygin, Christian Schill, S. Brauksiepe, B. Krauss, E. Avetissian, Nicola Bianchi, O. Mikloukho, Wolfgang Lorenzon, S. Potashov, H. Zohrabian, C. Scarlett, P. Bailey, H. Marukyan, G. P. Capitani, G.R. Court, Axel Maas, Andreas Schäfer, Eugenio Nappi, J. Franz, Andrey V. Izotov, A. Airapetian, P. Kitching, G. van der Steenhoven, J. Wendland, Michael Tytgat, P.W. Green, D. H. Potterveld, M. Bouwhuis, H. Böttcher, P. Di Nezza, F.H. Heinsius, Frank Ellinghaus, S. Taroian, V. Mexner, T. Lindemann, E. R. Kinney, V. Rappoport, P. Liebing, T. Wise, V. A. Korotkov, A. Schwind, R. Shanidze, S. Podiatchev, F. Schmidt, Martin Raithel, R. J. Holt, Y. Naryshkin, M. Beckmann, J. F. J. van den Brand, E. C. Aschenauer, V. Shutov, O. Grebeniouk, M. Stancari, Salvatore Frullani, J. J. M. Steijger, I. Sanjiev, P. F. Dalpiaz, K. Königsmann, Michael Düren, G. Orlandi, Naomi C R Makins, V. Baturin, S. Tessarin, P. Lenisa, J. Seibert, V. A. Kozlov, B. W. Filippone, D. Reggiani, J. Volmer, G. Elbakian, S. Belostotski, S. Bernreuther, Adel Terkulov, Yasuhiro Sakemi, M. Ehrenfried, R. De Leo, Erika Garutti, Y. Holler, V. Vikhrov, M. C. Simani, Manuella Vincter, Y. Gärber, P.K.A. de Witt Huberts, M. Hartig, E. Thomas, H. Avakian, Ralf Hertenberger, W.H.A. Hesselink, A. Gute, Dirk Ryckbosch, Othmane Bouhali, P. E. Reimer, M. Henoch, K. Suetsugu, R. Fabbri, T. A. Shibata, R.O. Avakian, H. E. Jackson, V. G. Krivokhijine, E. Devitsin, C. Baumgarten, N. Meyners, A. Borissov, K. Hafidi, V. A. Gapienko, H. Kolster, Alessandra Fantoni, G. Graw, M. Kopytin, A. Nass, Peter Jung, B. Seitz, D. Hasch, A. Laziev, K. Oganessyan, J. Wilbert, W.-D. Nowak, I. Brunn, A. Kisselev, H. Fischer, Jeffrey Brack, A. Nagaitsev, (Astro)-Particles Physics, and Photo Conversion Materials

Subjects
Quark, Particle physics, media_common.quotation_subject, Hadron, Nuclear Theory, FOS: Physical sciences, General Physics and Astronomy, Inelastic scattering, 01 natural sciences, Asymmetry, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Q(2)-DEPENDENCE, 0103 physical sciences, Proton spin crisis, SCATTERING, 010306 general physics, Nuclear Experiment, media_common, Physics, 010308 nuclear & particles physics, SUM, CONSTRAINTS, Deep inelastic scattering, 3. Good health, Baryon, POLARIMETER, NEUTRON, High Energy Physics::Experiment, POLARIZED HYDROGEN, Nucleon, RESONANCES, BEHAVIOR
Abstract

Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry $A_1$. Longitudinally polarised positrons were scattered off a longitudinally polarised hydrogen target for values of $Q^2$ between 1.2 and 12 GeV$^2$ and values of $W^2$ between 1 and 4 GeV$^2$. The average double-spin asymmetry in the nucleon resonance region is found to agree with that measured in deep-inelastic scattering at the same values of the Bjorken scaling variable $x$. This finding implies that the description of $A_1$ in terms of quark degrees of freedom is valid also in the nucleon resonance region for values of $Q^2$ above 1.6 GeV$^2$., 5 pages, 1 eps figure, table added, new references added, in print in Phys. Rev. Lett

Published
2002

22. Single-spin azimuthal asymmetries in electroproduction of neutral pions in semi-inclusive deep-inelastic scattering

Author

M. Henoch, W.H.A. Hesselink, K. Suetsugu, V. Djordjadze, Y. Holler, M. C. Simani, P.K.A. de Witt Huberts, H. J. Bulten, G. Ciullo, Christian Schill, W. Haeberli, S. Brauksiepe, P. Chumney, D. Robinson, V. Vikhrov, A. Rostomyan, A. R. Reolon, A. Avetissian, W.-D. Nowak, N. Meyners, Manuella Vincter, S. Potashov, H. Zohrabian, Michael Tytgat, G. S. Kyle, B. Hommez, B. Seitz, Axel Maas, A. Gute, S. Taroian, Hiroaki Kobayashi, P. Bailey, T. Wise, L. Felawka, F. Schmidt, B. D. Fox, Salvatore Frullani, S. Belostotski, E. De Sanctis, H. E. Jackson, V. G. Krivokhijine, A. Schwind, P. Di Nezza, Franco Garibaldi, M. Beckmann, J. F. J. van den Brand, Jeffrey Brack, P. Liebing, P. F. Dalpiaz, I. Brunn, A. Kisselev, P.W. Green, C. Baumgarten, G. M. Urciuoli, R. Van de Vyver, Klaus Rith, G. P. Capitani, D. Hasch, A. Simon, Thomas O'Neill, K. P. Schüler, D. Heesbeen, F.H. Heinsius, Frank Ellinghaus, E. R. Kinney, K. Negodaeva, M. Amarian, N. Koch, J. Wendland, D. H. Potterveld, E. Kotik, B. R. Owen, Yasuhiro Sakemi, E. Avetissian, Nicola Bianchi, O. Mikloukho, Evaristo Cisbani, M. Ruh, Y. Naryshkin, G. Iarygin, Dirk Ryckbosch, J. Stewart, A. Brüll, A. Airapetian, A. Laziev, A. Borissov, G. Hofman, V. A. Kozlov, M. Hartig, A. Jgoun, M. Ehrenfried, J. van Hunen, H. Marukyan, R. De Leo, B. Krauss, J. Franz, B. Tipton, M. Bouwhuis, C. Scarlett, H. Böttcher, S. F. Pate, O. Grebeniouk, Erika Garutti, U. Stosslein, J. J. M. Steijger, P. Lenisa, J. Seibert, Alessandra Fantoni, L. G. Greeniaus, L. Lagamba, Z. Akopov, B. W. Filippone, Eugenio Nappi, F. Sato, C. Weiskopf, D. Reggiani, K. McIlhany, A. Nass, Peter Jung, K. Sinram, L. De Nardo, V. Gharibyan, I.A. Savin, S. Yoneyama, G.R. Court, Wolfgang Lorenzon, Andreas Schäfer, M. McAndrew, F. Meissner, G. van der Steenhoven, K. Oganessyan, A. Golendukhin, T. Lindemann, H. Fischer, J. Wilbert, V. A. Korotkov, G. Graw, H. Kolster, D. De Schepper, K. Königsmann, V. Baturin, G. Rakness, G. Elbakian, W. Brückner, S. Bernreuther, K. Hafidi, R. J. Holt, F. Masoli, J. Visser, T. A. Shibata, R.O. Avakian, A. Nagaitsev, Michel Vetterli, N. Akopov, E. Devitsin, R. P. Redwine, M. Düren, R. Mussa, V. Rappoport, S. Tessarin, Ross Milner, C. A. Miller, J. Ely, Adel Terkulov, Andrey V. Izotov, H. Avakian, Othmane Bouhali, Y. Gärber, Valeria Muccifora, E. Thomas, G. Schnell, J. Kanesaka, Martin Raithel, E. C. Aschenauer, V. Shutov, B. Bains, I. Sanjiev, Naomi C R Makins, O.V. Teryaev, F. Menden, S. Yen, Ralf Kaiser, E. Steffens, G. Gavrilov, A. Fechtchenko, P. Kitching, Ralf Hertenberger, (Astro)-Particles Physics, and Photo Conversion Materials

Subjects
Quark, Nuclear and High Energy Physics, Particle physics, transverse [polarization], media_common.quotation_subject, FRAGMENTATION FUNCTIONS, FOS: Physical sciences, ODD PARTON DISTRIBUTIONS, HERMES, NUCLEONS, transverse momentum dependence, Asymmetry, fragmentation function, energy dependence, x-dependence, High Energy Physics - Experiment, Nuclear physics, 27.5 GeV, High Energy Physics - Experiment (hep-ex), Pion, 13.88.+e, ddc:530, deep inelastic scattering [positron p], Nuclear Experiment, QC, media_common, Physics, 13.60.-r, longitudinal [polarization], electroproduction [pi0], Scattering, QUARK, polarization [quark], Deep inelastic scattering, Polarization (waves), Transverse plane, DESY HERA Stor, 13.87.Fh, 14.20.Dh, analyzing power, polarized target [p], High Energy Physics::Experiment, asymmetry [spin], Lepton, experimental results
Abstract

A single-spin asymmetry in the azimuthal distribution of neutral pions relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. The analysing power in the sin(phi) moment of the cross section is 0.019 +/- 0.007(stat.) +/- 0.003(syst.). This result is compared to single-spin asymmetries for charged pion production measured in the same kinematic range. The pi^0 asymmetry is of the same size as the pi^+ asymmetry and shows a similar dependence on the relevant kinematic variables. The asymmetry is described by a phenomenological calculation based on a fragmentation function that represents sensitivity to the transverse polarization of the struck quark., Comment: 4 pages, 1 figure, replaced to correct eprint author field, 2nd replacement to correct figure; upper limit of model predictions are corrected. No correction to data or conclusions

Published
2001

23. Single-spin azimuthal asymmetry in exclusive electroproduction of pi^+ mesons

Author

A. Airapetian, N. Akopov, Z. Akopov, M. Amarian, E.C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, E. Avetissian, P. Bailey, V. Baturin, C. Baumgarten, M. Beckmann, S. Belostotski, S. Bernreuther, N. Bianchi, H. Böttcher, A. Borissov, O. Bouhali, M. Bouwhuis, J. Brack, S. Brauksiepe, A. Brüll, I. Brunn, H.J. Bulten, G.P. Capitani, P. Chumney, E. Cisbani, G. Ciullo, G.R. Court, P.F. Dalpiaz, R. De Leo, L. De Nardo, E. De Sanctis, D. De Schepper, E. Devitsin, P.K.A. de Witt Huberts, P. Di Nezza, M. Düren, M. Ehrenfried, G. Elbakian, F. Ellinghaus, J. Ely, R. Fabbri, A. Fantoni, A. Fechtchenko, L. Felawka, B.W. Filippone, H. Fischer, B. Fox, J. Franz, S. Frullani, Y. Gärber, F. Garibaldi, E. Garutti, G. Gavrilov, V. Gharibyan, G. Graw, O. Grebeniouk, P.W. Green, L.G. Greeniaus, A. Gute, W. Haeberli, K. Hafidi, M. Hartig, D. Hasch, D. Heesbeen, F.H. Heinsius, M. Henoch, R. Hertenberger, W.H.A. Hesselink, G. Hofman, Y. Holler, R.J. Holt, B. Hommez, G. Iarygin, A. Izotov, H.E. Jackson, A. Jgoun, P. Jung, R. Kaiser, A. Kisselev, P. Kitching, K. Königsmann, H. Kolster, V. Korotkov, E. Kotik, V. Kozlov, B. Krauss, V.G. Krivokhijine, G. Kyle, L. Lagamba, A. Laziev, P. Lenisa, P. Liebing, T. Lindemann, W. Lorenzon, A. Maas, N.C.R. Makins, H. Marukyan, F. Masoli, K. McIlhany, F. Meissner, F. Menden, V. Mexner, N. Meyners, O. Mikloukho, R. Milner, V. Muccifora, A. Nagaitsev, E. Nappi, Y. Naryshkin, A. Nass, K. Negodaeva, W.-D. Nowak, K. Oganessyan, T.G. O'Neill, B.R. Owen, S.F. Pate, S. Podiatchev, S. Potashov, D.H. Potterveld, M. Raithel, G. Rakness, V. Rappoport, R. Redwine, D. Reggiani, P. Reimer, A.R. Reolon, K. Rith, D. Robinson, A. Rostomyan, D. Ryckbosch, Y. Sakemi, I. Sanjiev, F. Sato, I. Savin, C. Scarlett, A. Schäfer, C. Schill, F. Schmidt, G. Schnell, K.P. Schüler, A. Schwind, J. Seibert, B. Seitz, T.-A. Shibata, V. Shutov, M.C. Simani, A. Simon, K. Sinram, E. Steffens, J.J.M. Steijger, J. Stewart, U. Stösslein, K. Suetsugu, S. Taroian, A. Terkulov, S. Tessarin, E. Thomas, B. Tipton, M. Tytgat, G.M. Urciuoli, J.F.J. van den Brand, G. van der Steenhoven, R. van de Vyver, M.C. Vetterli, V. Vikhrov, M.G. Vincter, J. Visser, J. Volmer, C. Weiskopf, J. Wendland, J. Wilbert, T. Wise, S. Yen, S. Yoneyama, H. Zohrabian, (Astro)-Particles Physics, and Photo Conversion Materials

Subjects
Nuclear and High Energy Physics, Particle physics, Meson, media_common.quotation_subject, Virtual particle, FOS: Physical sciences, 01 natural sciences, Asymmetry, NO, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Positron, 13.88.+e, 0103 physical sciences, 13.60.-r, 13.60.Le, 13.85.Fb, 010306 general physics, Nuclear Experiment, media_common, Physics, 010308 nuclear & particles physics, Scattering, LEADING ORDER, Polarization (waves), Physics and Astronomy, Condensed Matter::Strongly Correlated Electrons, High Energy Physics::Experiment, Nucleon, Lepton
Abstract

A single-spin asymmetry in the distribution of exclusively produced pi^+ mesons azimuthally around the virtual photon direction relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. Integrated over the experimental acceptance, the sin \phi moment of the polarization asymmetry of the cross section is measured to be -0.18 +/- 0.05 (stat.) +/- 0.02 (syst.). The asymmetry is also studied as a function of the relevant kinematic variables, and its magnitude is found to grow with decreasing x and increasing -t and vanish at t -> t_min (where x is the Bjorken scaling variable and t is the squared four-momentum transferred to the nucleon)., Comment: PLB accepted version, 6 pages, 4 figures, LaTex (revtex4), corrected typo

Published
2001
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24. Measurement of the Beam-Spin Azimuthal Asymmetry associated with Deep Virtual Compton Scattering

Author

J. Wilbert, D. De Schepper, S. Potashov, H. Zohrabian, W.-D. Nowak, G. S. Kyle, J. Stewart, I. Brunn, A. Kisselev, H. Fischer, L. Felawka, G. Graw, V. A. Korotkov, P. Lenisa, J. Seibert, H. Kolster, K. McIlhany, I.A. Savin, K. Königsmann, V. Baturin, B. D. Fox, W. Haeberli, B. Seitz, Yasuhiro Sakemi, E. Thomas, G. Schnell, H. J. Bulten, G. Ciullo, K. Sinram, P. Di Nezza, L. De Nardo, G. M. Urciuoli, B. W. Filippone, D. Reggiani, G.R. Court, Andreas Schäfer, Christian Schill, G. Elbakian, W. Brückner, B. Hommez, S. Bernreuther, H. Avakian, Othmane Bouhali, K. Negodaeva, M. McAndrew, M. Amarian, G. P. Capitani, P. Liebing, S. Brauksiepe, R. Van de Vyver, R. J. Holt, Michael Tytgat, F. Masoli, J. Visser, Klaus Rith, D. Heesbeen, M. Ruh, N. Meyners, V. Gharibyan, P. Chumney, E. Kotik, Evaristo Cisbani, S. Taroian, U. Stosslein, Salvatore Frullani, A. Rostomyan, R. Fabbri, T. A. Shibata, L. Lagamba, M. Hartig, A. R. Reolon, R.O. Avakian, Z. Akopov, P. F. Dalpiaz, G. van der Steenhoven, A. Avetissian, A. Golendukhin, T. Lindemann, Andrey V. Izotov, A. Airapetian, G. Iarygin, O. Grebeniouk, E. Devitsin, Axel Maas, A. Borissov, J. Wendland, A. Brüll, M. Bouwhuis, Dirk Ryckbosch, B. Tipton, H. Böttcher, D. H. Potterveld, S. F. Pate, H. Marukyan, F. Meissner, Jeffrey Brack, E. De Sanctis, Franco Garibaldi, G. Hofman, C. A. Miller, R. P. Redwine, J. van Hunen, Martin Raithel, Ralf Hertenberger, J. Franz, K. Oganessyan, L. G. Greeniaus, C. Weiskopf, J. Ely, Thomas O'Neill, K. Hafidi, Eugenio Nappi, A. Schwind, V. Vikhrov, V. Rappoport, J. Kanesaka, Manuella Vincter, W.H.A. Hesselink, Ross Milner, K. P. Schüler, F. Sato, E. C. Aschenauer, D. Hasch, V. Shutov, J. J. M. Steijger, G. Rakness, T. Wise, A. Laziev, Y. Holler, V. A. Kozlov, S. Yoneyama, N. Koch, F. Schmidt, A. Nagaitsev, Wolfgang Lorenzon, Michel Vetterli, M. Beckmann, J. F. J. van den Brand, B. Bains, M. C. Simani, Erika Garutti, N. Akopov, P.K.A. de Witt Huberts, Valeria Muccifora, A. Gute, Alessandra Fantoni, I. Sanjiev, E. Avetissian, Nicola Bianchi, O. Mikloukho, A. Nass, Peter Jung, M. Düren, R. Mussa, Naomi C R Makins, S. Tessarin, M. Ehrenfried, R. De Leo, F. Menden, Adel Terkulov, S. Yen, Ralf Kaiser, Y. Gärber, E. Steffens, G. Gavrilov, A. Simon, B. R. Owen, A. Fechtchenko, A. Jgoun, M. Henoch, K. Suetsugu, Hiroaki Kobayashi, P. Bailey, P.W. Green, H. E. Jackson, V. G. Krivokhijine, C. Baumgarten, P. Kitching, D. Robinson, B. Krauss, C. Scarlett, F.H. Heinsius, Frank Ellinghaus, E. R. Kinney, Y. Naryshkin, S. Belostotski, (Astro)-Particles Physics, and Photo Conversion Materials

Subjects
HERMES experiment, Particle physics, Photon, media_common.quotation_subject, interference, General Physics and Astronomy, HERMES, dependence [helicity], Asymmetry, High Energy Physics - Experiment, 24.85.+p, Nuclear physics, 13.60.Fz, ddc:550, deep inelastic scattering [positron p], 26.7 GeV, Nuclear Experiment, NUCLEON, media_common, Physics, longitudinal [polarization], Scattering, ELECTROPRODUCTION, 14.20.Dh, Compton scattering, DESY, HERA, Bethe-Heitler [approximation], DESY HERA Stor, asymmetry [angular distribution], off-shell [Compton scattering], analyzing power, Physics::Accelerator Physics, High Energy Physics::Experiment, polarized beam [positron], electroproduction [photon], Beam (structure), experimental results
Abstract

The beam-spin asymmetry in hard electroproduction of photons has been measured for the first time. The data have been accumulated by the HERMES experiment at DESY using the HERA 27.6 GeV longitudinally polarized positron beam and an unpolarized hydrogen gas target. The asymmetry in the azimuthal distribution of the produced photons in the angle phi relative to the lepton scattering plane was determined with respect to the helicity state of the incoming positron beam. The beam-spin analyzing power in the sin(phi) moment was measured to be -0.23 +/- 0.04(stat) +/- 0.03(syst) in the missing-mass range below 1.7 GeV. The observed asymmetry is attributed to the interference of the Bethe-Heitler and deeply-virtual Compton scattering processes., Comment: 6 pages, 5 figures, revised experimental description

Published
2001

25. The Q2 dependence of the generalized Gerasimov-Drell-Hearn integral for the proton

Author

A. Airapetian, N. Akopov, I. Akushevich, M. Amarian, J. Arrington, E.C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, E. Avetissian, P. Bailey, B. Bains, C. Baumgarten, M. Beckmann, S. Belostotski, S. Bernreuther, N. Bianchi, H. Böttcher, A. Borissov, M. Bouwhuis, J. Brack, S. Brauksiepe, B. Braun, W. Brückner, A. Brüll, P. Budz, H.J. Bulten, G.P. Capitani, P. Carter, P. Chumney, E. Cisbani, G.R. Court, P.F. Dalpiaz, R. De Leo, L. De Nardo, E. De Sanctis, D. De Schepper, E. Devitsin, P.K.A. de Witt Huberts, P. Di Nezza, V. Djordjadze, M. Düren, A. Dvoredsky, G. Elbakian, J. Ely, A. Fantoni, A. Fechtchenko, M. Ferro-Luzzi, K. Fiedler, B.W. Filippone, H. Fischer, B. Fox, J. Franz, S. Frullani, Y. Gärber, F. Garibaldi, E. Garutti, G. Gavrilov, V. Gharibyan, A. Golendukhin, G. Graw, O. Grebeniouk, P.W. Green, L.G. Greeniaus, A. Gute, W. Haeberli, M. Hartig, D. Hasch, D. Heesbeen, F.H. Heinsius, M. Henoch, R. Hertenberger, W. Hesselink, P. Hoffmann-Rothe, G. Hofman, Y. Holler, R.J. Holt, B. Hommez, G. Iarygin, M. Iodice, A. Izotov, H.E. Jackson, A. Jgoun, P. Jung, R. Kaiser, J. Kanesaka, E. Kinney, A. Kisselev, P. Kitching, H. Kobayashi, N. Koch, K. Königsmann, H. Kolster, V. Korotkov, E. Kotik, V. Kozlov, V.G. Krivokhijine, G. Kyle, L. Lagamba, A. Laziev, P. Lenisa, T. Lindemann, W. Lorenzon, N.C.R. Makins, J.W. Martin, H. Marukyan, F. Masoli, M. McAndrew, K. McIlhany, R.D. McKeown, F. Menden, A. Metz, N. Meyners, O. Mikloukho, C.A. Miller, R. Milner, V. Mitsyn, V. Muccifora, R. Mussa, A. Nagaitsev, E. Nappi, Y. Naryshkin, A. Nass, K. Negodaeva, W.-D. Nowak, T.G. O'Neill, R. Openshaw, J. Ouyang, B.R. Owen, S.F. Pate, S. Potashov, D.H. Potterveld, G. Rakness, V. Rappoport, R. Redwine, D. Reggiani, A.R. Reolon, R. Ristinen, K. Rith, D. Robinson, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, C. Scarlett, A. Schäfer, C. Schill, F. Schmidt, G. Schnell, K.P. Schüler, A. Schwind, J. Seibert, B. Seitz, T.-A. Shibata, T. Shin, V. Shutov, C. Simani, A. Simon, K. Sinram, E. Steffens, J.J.M. Steijger, J. Stewart, U. Stösslein, K. Suetsugu, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, S. Tessarin, E. Thomas, B. Tipton, M. Tytgat, G.M. Urciuoli, J.F.J. van den Brand, G. van der Steenhoven, R. van de Vyver, J.J. van Hunen, M.C. Vetterli, V. Vikhrov, M.G. Vincter, J. Visser, E. Volk, C. Weiskopf, J. Wendland, J. Wilbert, T. Wise, S. Yen, S. Yoneyama, H. Zohrabian, (Astro)-Particles Physics, and Photo Conversion Materials

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Range (particle radiation), Proton, Nuclear Theory, FOS: Physical sciences, Virtual particle, Square (algebra), High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Quantum electrodynamics, High Energy Physics::Experiment, Twist, Nuclear Experiment, Sign (mathematics)
Abstract

The dependence on Q^2 (the negative square of the 4-momentum of the exchanged virtual photon) of the generalised Gerasimov-Drell-Hearn integral for the proton has been measured in the range 1.2 GeV^2 < Q^2 < 12 GeV^2 by scattering longitudinally polarised positrons on a longitudinally polarised hydrogen gas target. The contributions of the nucleon-resonance and deep-inelastic regions to this integral have been evaluated separately. The latter has been found to dominate for Q^2 > 3 GeV^2, while both contributions are important at low Q^2. The total integral shows no significant deviation from a 1/Q^2 behaviour in the measured Q^2 range, and thus no sign of large effects due to either nucleon-resonance excitations or non-leading twist., 9 pages, 3 figures, 1 table

Published
2000

26. 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

27. 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

28. The HERMES Back Drift Chambers

Author

S Bernreuther, A.B Borissov, H Böttcher, S Brons, W Brückner, A Buchsteiner, M Ferstl, Y Gärber, A Gute, U Harder, D Hasch, M Kirsch, B Krause, W.A Lachnit, F Meißner, G Modrak, F Neunreither, W.-D Nowak, M Pohl, K Rith, H.O Roloff, H Russo, F Schmidt, A.E Schwind, and W Wander

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Spectrometer, business.industry, Resolution (electron density), FOS: Physical sciences, Tracking system, High Energy Physics - Experiment, Bending magnets, High Energy Physics - Experiment (hep-ex), Optics, Planar, Calibration, business, Instrumentation
Abstract

The tracking system of the HERMES spectrometer behind the bending magnet consists of two pairs of large planar 6-plane drift chambers. The design and performance of these chambers is described. This description comprises details on the mechanical and electronical design, information about the gas mixture used and its properties, results on alignment, calibration, resolution, and efficiencies, and a discussion of the experience gained through the first three years of operation., Comment: 21 pages, LaTex, 16 figures included

Published
1998
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29. 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

30. Measurement of the tensor structure function b1 of the deuteron.

Author

Airapetian A, Akopov N, Akopov Z, Amarian M, Ammosov VV, Andrus A, Aschenauer EC, Augustyniak W, Avakian R, Avetissian A, Avetissian E, Bailey P, Balin D, Baturin V, Beckmann M, Belostotski S, Bernreuther S, Bianchi N, Blok HP, Böttcher H, Borissov A, Borysenko A, Bouwhuis M, Brack J, Brüll A, Bryzgalov V, Capitani GP, Chen T, Chiang HC, Ciullo G, Contalbrigo M, Dalpiaz PF, De Leo R, Demey M, De Nardo L, De Sanctis E, Devitsin E, Di Nezza P, Dreschler J, Düren M, Ehrenfried M, Elalaoui-Moulay A, Elbakian G, Ellinghaus F, Elschenbroich U, Fabbri R, Fantoni A, Fechtchenko A, Felawka L, Fox B, Frullani S, Gapienko G, Gapienko V, Garibaldi F, Garrow K, Garutti E, Gaskell D, Gavrilov G, Gharibyan V, Graw G, Grebeniouk O, Greeniaus LG, Gregor IM, Hafidi K, Hartig M, Hasch D, Heesbeen D, Henoch M, Hertenberger R, Hesselink WH, Hillenbrand A, Hoek M, Holler Y, Hommez B, Iarygin G, Ivanilov A, Izotov A, Jackson HE, Jgoun A, Kaiser R, Kinney E, Kisselev A, Kopytin M, Korotkov V, Kozlov V, Krauss B, Krivokhijine VG, Lagamba L, Lapikás L, Laziev A, Lenisa P, Liebing P, Linden-Levy LA, Lipka K, Lorenzon W, Lu H, Lu J, Lu S, Ma BQ, Maiheu B, Makins NC, Mao Y, Marianski B, Marukyan H, Masoli F, Mexner V, Meyners N, Mikloukho O, Miller CA, Miyachi Y, Muccifora V, Nagaitsev A, Nappi E, Naryshkin Y, Nass A, Negodaev M, Nowak WD, Oganessyan K, Ohsuga H, Pickert N, Potashov S, Potterveld DH, Raithel M, Reggiani D, Reimer PE, Reischl A, Reolon AR, Riedl C, Rith K, Rosner G, Rostomyan A, Rubacek L, Rubin J, Ryckbosch D, Salomatin Y, Sanjiev I, Savin I, Schäfer A, Schill C, Schnell G, Schüler KP, Seele J, Seidl R, Seitz B, Shanidze R, Shearer C, Shibata TA, Shutov V, Simani MC, Sinram K, Stancari M, Statera M, Steffens E, Steijger JJ, Stenzel H, Stewart J, Stinzing F, Stösslein U, Tait P, Tanaka H, Taroian S, Tchuiko B, Terkulov A, Tkabladze A, Trzcinski A, Tytgat M, Vandenbroucke A, van der Nat PB, van der Steenhoven G, Vetterli MC, Vikhrov V, Vincter MG, Vogel C, Vogt M, Volmer J, Weiskopf C, Wendland J, Wilbert J, Ye Y, Ye Z, Yen S, Zihlmann B, and Zupranski P

Abstract

The Hermes experiment has investigated the tensor spin structure of the deuteron using the 27.6 GeV/c positron beam of DESY HERA. The use of a tensor-polarized deuteron gas target with only a negligible residual vector polarization enabled the first measurement of the tensor asymmetry A(d)zz and the tensor structure function b(d)1 for average values of the Bjorken variable 0.01< <0.45 and of the negative of the squared four-momentum transfer 0.5 GeV2 < <5 GeV2. The quantities A(d)zz and b(d)1 are found to be nonzero. The rise of b(d)1 for decreasing values of x can be interpreted to originate from the same mechanism that leads to nuclear shadowing in unpolarized scattering.

Published
2005
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31. Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering.

Author

Airapetian A, Akopov N, Akopov Z, Amarian M, Ammosov VV, Andrus A, Aschenauer EC, Augustyniak W, Avakian R, Avetissian A, Avetissian E, Bailey P, Baturin V, Baumgarten C, Beckmann M, Belostotski S, Bernreuther S, Bianchi N, Blok HP, Böttcher H, Borissov A, Bouwhuis M, Brack J, Brüll A, Bryzgalov V, Capitani GP, Chiang HC, Ciullo G, Contalbrigo M, Dalpiaz PF, De Leo R, De Nardo L, De Sanctis E, Devitsin E, Di Nezza P, Düren M, Ehrenfried M, Elalaoui-Moulay A, Elbakian G, Ellinghaus F, Elschenbroich U, Ely J, Fabbri R, Fantoni A, Fechtchenko A, Felawka L, Fox B, Franz J, Frullani S, Gärber Y, Gapienko G, Gapienko V, Garibaldi F, Garrow K, Garutti E, Gaskell D, Gavrilov G, Gharibyan V, Graw G, Grebeniouk O, Greeniaus LG, Hafidi K, Hartig M, Hasch D, Heesbeen D, Henoch M, Hertenberger R, Hesselink WH, Hillenbrand A, Hoek M, Holler Y, Hommez B, Iarygin G, Ivanilov A, Izotov A, Jackson HE, Jgoun A, Kaiser R, Kinney E, Kisselev A, Königsmann K, Kopytin M, Korotkov V, Kozlov V, Krauss B, Krivokhijine VG, Lagamba L, Lapikás L, Laziev A, Lenisa P, Liebing P, Lindemann T, Lipka K, Lorenzon W, Lu J, Maiheu B, Makins NC, Marianski B, Marukyan H, Masoli F, Mexner V, Meyners N, Mikloukho O, Miller CA, Miyachi Y, Muccifora V, Nagaitsev A, Nappi E, Naryshkin Y, Nass A, Negodaev M, Nowak WD, Oganessyan K, Ohsuga H, Orlandi G, Pickert N, Potashov S, Potterveld DH, Raithel M, Reggiani D, Reimer PE, Reischl A, Reolon AR, Riedl C, Rith K, Rosner G, Rostomyan A, Rubacek L, Ryckbosch D, Salomatin Y, Sanjiev I, Savin I, Scarlett C, Schäfer A, Schill C, Schnell G, Schüler KP, Schwind A, Seele J, Seidl R, Seitz B, Shanidze R, Shearer C, Shibata TA, Shutov V, Simani MC, Sinram K, Stancari M, Statera M, Steffens E, Steijger JJ, Stewart J, Stösslein U, Tait P, Tanaka H, Taroian S, Tchuiko B, Terkulov A, Tkabladze A, Trzcinski A, Tytgat M, Vandenbroucke A, Van Der Nat P, Van Der Steenhoven G, Vetterli MC, Vikhrov V, Vincter MG, Visser J, Vogel C, Vogt M, Volmer J, Weiskopf C, Wendland J, Wilbert J, Ybeles Smit G, Yen S, Zihlmann B, Zohrabian H, and Zupranski P

Abstract

Double-spin asymmetries of semiinclusive cross sections for the production of identified pions and kaons have been measured in deep inelastic scattering of polarized positrons on a polarized deuterium target. Five helicity distributions including those for three sea quark flavors were extracted from these data together with reanalyzed previous data for identified pions from a hydrogen target. These distributions are consistent with zero for all three sea flavors. A recently predicted flavor asymmetry in the polarization of the light quark sea appears to be disfavored by the data.

Published
2004
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32. Evidence for quark-hadron duality in the proton spin asymmetry A1.

Author

Airapetian A, Akopov N, Akopov Z, Amarian M, Ammosov VV, Aschenauer EC, Avakian H, Avakian R, Avetissian A, Avetissian E, Bailey P, Baturin V, Baumgarten C, Beckmann M, Belostotski S, Bernreuther S, Bianchi N, Blok HP, Böttcher H, Borissov A, Bouhali O, Bouwhuis M, Brack J, Brauksiepe S, Brüll A, Brunn I, Bulten HJ, Capitani GP, Cisbani E, Ciullo G, Court GR, Dalpiaz PF, De Leo R, De Nardo L, De Sanctis E, Devitsin E, de Witt Huberts PK, Di Nezza P, Düren M, Ehrenfried M, Elbakian G, Ellinghaus F, Elschenbroich U, Ely J, Fabbri R, Fantoni A, Fechtchenko A, Felawka L, Filippone BW, Fischer H, Fox B, Franz J, Frullani S, Gärber Y, Gapienko V, Garibaldi F, Garutti E, Gavrilov G, Gharibyan V, Graw G, Grebeniouk O, Green PW, Greeniaus LG, Gute A, Haeberli W, Hafidi K, Hartig M, Hasch D, Heesbeen D, Heinsius FH, Henoch M, Hertenberger R, Hesselink WH, Hofman G, Holler Y, Holt RJ, Hommez B, Iarygin G, Izotov A, Jackson HE, Jgoun A, Jung P, Kaiser R, Kinney E, Kisselev A, Kitching P, Königsmann K, Kolster H, Kopytin M, Korotkov V, Kotik E, Kozlov V, Krauss B, Krivokhijine VG, Kyle G, Lagamba L, Laziev A, Lenisa P, Liebing P, Lindemann T, Lorenzon W, Maas A, Makins NC, Marukyan H, Masoli F, Menden F, Mexner V, Meyners N, Mikloukho O, Miller CA, Muccifora V, Nagaitsev A, Nappi E, Naryshkin Y, Nass A, Negodaeva K, Nowak WD, Oganessyan K, Orlandi G, Podiatchev S, Potashov S, Potterveld DH, Raithel M, Rappoport V, Reggiani D, Reimer P, Reischl A, Reolon AR, Rith K, Rostomyan A, Ryckbosch D, Sakemi Y, Sanjiev I, Sato F, Savin I, Scarlett C, Schäfer A, Schill C, Schmidt F, Schnell G, Schüler KP, Schwind A, Seibert J, Seitz B, Shanidze R, Shibata TA, Shutov V, Simani MC, Sinram K, Stancari M, Steffens E, Steijger JJ, Stewart J, Stösslein U, Suetsugu K, Taroian S, Terkulov A, Tessarin S, Thomas E, Tipton B, Tytgat M, Urciuoli GM, van den Brand JF, van der Steenhoven G, van de Vyver R, Vetterli MC, Vikhrov V, Vincter MG, Visser J, Volmer J, Weiskopf C, Wendland J, Wilbert J, Wise T, Yen S, Yoneyama S, Zihlmann B, and Zohrabian H

Abstract

Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry A1. Longitudinally polarized positrons were scattered off a longitudinally polarized hydrogen target for values of Q2 between 1.2 and 12 GeV2 and values of W2 between 1 and 4 GeV2. The average double-spin asymmetry in the nucleon resonance region is found to agree with that measured in deep-inelastic scattering at the same values of the Bjorken scaling variable x. This finding implies that the description of A1 in terms of quark degrees of freedom is valid also in the nucleon resonance region for values of Q2 above 1.6 GeV2.

Published
2003
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33. Q2 dependence of nuclear transparency for exclusive rho0 production.

Author

Airapetian A, Akopov N, Akopov Z, Amarian M, Ammosov VV, Andrus A, Aschenauer EC, Augustyniak W, Avakian R, Avetissian A, Avetissian E, Bailey P, Baturin V, Baumgarten C, Beckmann M, Belostotski S, Bernreuther S, Bianchi N, Blok HP, Böttcher H, Borissov A, Bouwhuis M, Brack J, Brüll A, Brunn I, Capitani GP, Chiang HC, Ciullo G, Contalbrigo M, Court GR, Dalpiaz PF, De Leo R, De Nardo L, De Sanctis E, Devitsin E, Di Nezza P, Düren M, Ehrenfried M, Elalaoui-Moulay A, Elbakian G, Ellinghaus F, Elschenbroich U, Ely J, Fabbri R, Fantoni A, Fechtchenko A, Felawka L, Fox B, Franz J, Frullani S, Gärber Y, Gapienko G, Gapienko V, Garibaldi F, Garutti E, Gaskell D, Gavrilov G, Gharibyan V, Graw G, Grebeniouk O, Greeniaus LG, Haeberli W, Hafidi K, Hartig M, Hasch D, Heesbeen D, Henoch M, Hertenberger R, Hesselink WH, Hillenbrand A, Holler Y, Hommez B, Iarygin G, Izotov A, Jackson HE, Jgoun A, Kaiser R, Kinney E, Kisselev A, Königsmann K, Kolster H, Kopytin M, Korotkov V, Kozlov V, Krauss B, Krivokhijine VG, Lagamba L, Lapikás L, Laziev A, Lenisa P, Liebing P, Lindemann T, Lorenzon W, Makins NC, Marukyan H, Masoli F, Menden F, Mexner V, Meyners N, Mikloukho O, Miller CA, Miyachi Y, Muccifora V, Nagaitsev A, Nappi E, Naryshkin Y, Nass A, Negodaeva K, Nowak WD, Oganessyan K, Ohsuga H, Orlandi G, Podiatchev S, Potashov S, Potterveld DH, Raithel M, Reggiani D, Reimer P, Reischl A, Reolon AR, Rith K, Rosner G, Rostomyan A, Ryckbosch D, Sanjiev I, Savin I, Scarlett C, Schäfer A, Schill C, Schnell G, Schüler KP, Schwind A, Seibert J, Seitz B, Shanidze R, Shibata TA, Shutov V, Simani MC, Sinram K, Stancari M, Statera M, Steffens E, Steijger JJ, Stewart J, Stösslein U, Tanaka H, Taroian S, Tchuiko B, Terkulov A, Tessarin S, Thomas E, Tkabladze A, Trzcinski A, Tytgat M, Urciuoli GM, Van Der Nat P, Van Der Steenhoven G, Van De Vyver R, Vetterli MC, Vikhrov V, Vincter MG, Visser J, Vogt M, Volmer J, Weiskopf C, Wendland J, Wilbert J, Wise T, Yen S, Yoneyama S, Zihlmann B, Zohrabian H, and Zupranski P

Abstract

Exclusive coherent and incoherent electroproduction of the rho(0) meson from 1H and 14N targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (-Q2). The ratio of 14N to 1H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing l(c) for coherent (incoherent) rho(0) electroproduction. For fixed l(c), a rise of nuclear transparency with Q2 is observed for both coherent and incoherent rho(0) production, which is in agreement with theoretical calculations of color transparency.

Published
2003
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