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Now showing items 17 - 27 of 27

  • Measurement of the x- and Q(2)-dependence of the asymmetry A(1) on the nucleon RID A-2074-2012 RID E-8618-2010 RID B-4083-2012

    Dharmawardane, K. V.   Kuhn, S. E.   Bosted, P.   Prok, Y.   Adams, G.   Ambrozewicz, P.   Anghinolfi, M.   Asryan, G.   Avakian, H.   Bagdasaryan, H.   Baillie, N.   Ball, J. P.   Baltzell, N. A.   Barrow, S.   Batourine, V.   Battaglieri, M.   Beard, K.   Bedlinskiy, I.   Bektasoglu, M.   Bellis, M.   Benmouna, N.   Biselli, A. S.   Bonner, B. E.   Bouchigny, S.   Boiarinov, S.   Bradford, R.   Branford, D.   Brooks, W. K.   Bultmann, S.   Burkert, V. D.   Butuceanu, C.   Calarco, J. R.   Careccia, S. L.   Carman, D. S.   Carnahan, B.   Cazes, A.   Chen, S.   Cole, P. L.   Collins, P.   Coltharp, P.   Cords, D.   Corvisiero, P.   Crabb, D.   Crannell, H.   Crede, V.   Cummings, J. P.   De Masi, R.   DeVita, R.   De Sanctis, E.   Degtyarenko, P. V.   Denizli, H.   Dennis, L.   Deur, A.   Djalali, C.   Dodge, G. E.   Donnelly, J.   Doughty, D.   Draigovitsch, P.   Dugger, M.   Dytman, S.   Dzyubak, O. P.   Egiyan, H.   Egiyan, K. S.   Elouadrhiri, L.   Eugenio, P.   Fatemi, R.   Fedotov, G.   Feuerbach, R. J.   Forest, T. A.   Funsten, H.   Garcon, M.   Gavalian, G.   Gilfoyle, G. P.   Giovanetti, K. L.   Girod, F. X.   Goetz, J. T.   Golovatch, E.   Gonenc, A.   Gothe, R. W.   Griffioen, K. A.   Guidal, M.   Guillo, M.   Guler, N.   Guo, L.   Gyurjyan, V.   Hadjidakis, C.   Hafidi, K.   Hakobyan, R. S.   Hardie, J.   Heddle, D.   Hersman, F. W.   Hicks, K.   Hleiqawi, I.   Holtrop, M.   Huertas, M.   Hyde-Wriyht, C. E.   Ilieva, Y.   Ireland, D. G.   Ishkhanov, B. S.   Isupov, E. L.   Ito, M. M.   Jenkins, D.   Jo, H. S.   Joo, K.   Juengst, H. G.   Keith, C.   Kellie, J. D.   Khandaker, M.   Kim, K. Y.   Kim, K.   Kim, W.   Klein, A.   Klein, F. J.   Klusman, M.   Kossov, M.   Kramer, L. H.   Kubarovsky, V.   Kuhn, J.   Kuleshov, S. V.   Lachniet, J.   Laget, J. M.   Langheinrich, J.   Lawrence, D.   Li, Ji   Lima, A. C. S.   Livingston, K.   Lu, H.   Lukashin, K.   MacCormick, M.   Manak, J. J.   Markov, N.   McAleer, S.   McKinnon, B.   McNabb, J. W. C.   Mecking, B. A.   Mestayer, M. D.   Meyer, C. A.   Mibe, T.   Mikhailov, K.   Minehart, R.   Mirazita, M.   Miskimen, R.   Mokeev, V.   Morand, L.   Morrow, S. A.   Moteabbed, M.   Mueller, J.   Mutchler, G. S.   Nadel-Turonski, P.   Napolitano, J.   Nasseripour, R.   Niccolai, S.   Niculescu, G.   Niculescu, I.   Niczyporuk, B. B.   Niroula, M. R.   Nyazov, R. A.   Nozar, M.   O'Rielly, G. V.   Osipenko, M.   Ostrovidov, A. I.   Park, K.   Pasyuk, E.   Paterson, C.   Philips, S. A.   Pierce, J.   Pivnyuk, N.   Pocanic, D.   Pogorelko, O.   Polli, E.   Pozdniakov, S.   Preedom, B. M.   Price, J. W.   Protopopescu, D.   Qin, L. M.   Raue, B. A.   Riccardi, G.   Ricco, G.   Ripani, M.   Ritchie, B. G.   Ronchetti, F.   Rosner, G.   Rossi, P.   Rowntree, D.   Rubin, P. D.   Sabatie, E.   Salgado, C.   Santoro, J. P.   Sapunenko, V.   Schumacher, R. A.   Serov, V. S.   Sharabian, Y. G.   Shaw, J.   Shvedunov, N. V.   Skabelin, A. V.   Smith, E. S.   Smith, L. C.   Sober, D. I.   Stavinsky, A.   Stepanyan, S. S.   Stepanyan, S.   Stokes, B. E.   Stoler, P.   Strakovsky, I. I.   Strauch, S.   Suleiman, R.   Taiuti, M.   Taylor, S.   Tedeschi, D. J.   Thoma, U.   Thompson, R.   Tkabladze, A.   Tkachenko, S.   Todor, L.   Tur, C.   Ungaro, M.   Vineyard, M. F.   Vlassov, A. V.   Weinstein, L. B.   Weygand, D. P.   Williams, M.   Wolin, E.   Wood, M. H.   Yegneswaran, A.   Yun, J.   Zana, L.   Zhang, J.   Zhao, B.   Zhao, Z.  

    We report results for the virtual photon asymmetry A I on the nucleon from new Jefferson Lab measurements. The experiment, which used the CEBAF Large Acceptance Spectrometer and longitudinally polarized proton ((NH3)-N-15) and deuteron ((ND3)-N-15) targets, collected data with a longitudinally polarized electron beam at energies between 1.6 GeV and 5.7 GeV. In the present. Letter, we concentrate on our results for A(1) (x, Q(2)) and the related ratio g(1)/F-1 (x, Q(2))) in the resonance and the deep inelastic regions for our J west and highest beam energies, covering a range in momentum transfer Q(2) from 0.05 to 5.0 (GeV/c)(2) and in final-state invariant mass W up to about 3 GeV. Our data show detailed structure in the resonance re-ion, which leads to a strong Q(2) dependence of A(1) (x, Q(2)) to. W below 2 GeV. At higher W, a smooth approach to the scaling limit, established by earlier experiments, can be seen, but A I (x, Q(2)) is not strictly Q(2)-independent. We add significantly to the world data set at high x, up to x = 0.6. Our data exceed the SU(6)-symmetric quark model expectation for both the proton and the deuteron while being consistent with a negative d-quark polarization up to our highest x. This data set should improve next-to-leading order (NLO) pQCD fits of the parton polarization distributions. (c) 2006 Elsevier B.V.All rights reserved.
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  • Evidence for Delta(2200)7/2(-) from photoproduction and consequence for chiral-symmetry restoration at high mass

    Anisovich, A. V.   Burkert, V.   Hartmann, J.   Klempt, E.   Nikonov, V. A.   Pasyuk, E.   Sarantsev, A. V.   Strauch, S.   Thoma, U.  

    We report a partial-wave analysis of new data on the double-polarization variable Efor the reactions gamma p ->pi(+)n and gamma p -> pi(0)p and of further data published earlier. The analysis within the Bonn-Gatchina (BnGa) formalism reveals evidence for a poorly known baryon resonance, the one-star Delta(2200) 7/2(-). This is the lowest-mass Delta* resonance with spin-parity J(P)=3D 7/2(-). Its mass is significantly higher than the mass of its parity partner Delta(1950) 7/2(+) which is the lowest-mass Delta* resonance with spin-parity J(P)=3D 7/2(+). It has been suggested that chiral symmetry might be restored in the high-mass region of hadron excitations, and that these two resonances should be degenerate in mass. Our findings are in conflict with this prediction. (C) 2016 The Author(s). Published by Elsevier B. V. This is an open access article under the CC BY license.
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  • Study of hyperons with CLAS and CLAS12

    Pasyuk, E.  

    Hadron spectroscopy and baryon spectroscopy in particular represents a large part of the experimental program with CLAS at Jefferson Lab. Within this program a substantial amount of data on hyperon production and properties has been accumulated. This includes photo- and electro-production of Lambda and Sigma hyperons and their excited states and also Xi hyperons. Some of the highlights of this program will be presented together with plans to extend this program with CLAS12 after CEBAF upgrade to 12 GeV. [All rights reserved Elsevier].
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  • Dynamic magnetic shield for the CLAS12 central TOF detector photomultiplier tubes

    Baturin, V.   Burkert, V.   Carman, D. S.   Elouadrhyri, L.   Grilli, D.   Kashy, D.   Pasyuk, E.   Quettier, L.   Wieland, B.  

    The Central Time-of-Flight detector for the Jefferson Laboratory 12-GeV upgrade is being designed with linear-focused photomultiplier tubes that require a robust magnetic shield against the CLAS12 main 5-T solenoid fringe fields of 100 mT (1 kG). Theoretical consideration of a ferromagnetic cylinder in an axial field has demonstrated that its shielding capability decreases with increasing length. This observation has been confirmed with finite element analysis using POISSON model software. Several shields composed of coaxial ferromagnetic cylinders have been studied. All difficulties caused by saturation effects were overcome with a novel dynamical shield, which utilizes a demagnetizing solenoid between the shielding cylinders. Basic dynamical shields for ordinary linear-focused 2-in. photomultiplier tubes were designed and tested both with models and experimental prototypes at different external field and demagnetizing current values. Our shield design reduces the 1 kG external axial field by a factor of 5000. (C) 2011 Elsevier B.V All rights reserved.
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  • High precision measurement of Compton scattering in the 5 GeV region

    Ambrozewicz, P.   Ye, L.   Prok, Y.   Larin, I   Ahmidouch, A.   Baker, K.   Baturin, V   Benton, L.   Bernstein, A.   Burkert, V   Clinton, E.   Cole, P. L.   Collins, P.   Dale, D.   Danagoulian, S.   Davidenko, G.   Demirchyan, R.   Deur, A.   Dolgolenko, A.   Dutta, D.   Dzyubenko, G.   Evdokimov, A.   Fedotov, G.   Feng, J.   Gabrielyan, M.   Gan, L.   Gao, H.   Gasparian, A.   Gevorkyan, N.   Gevorkyan, S.   Glamazdin, A.   Goryachev, V   Guo, L.   Gyurjyan, V   Hardy, K.   He, J.   Isupov, E.   Ito, M. M.   Jiang, L.   Kang, H.   Kashy, D.   Khandaker, M.   Kingsberry, P.   Klein, F.   Kolarkar, A.   Konchatnyi, M.   Korchin, O.   Korsch, W.   Kosinov, O.   Kowalski, S.   Kubantsev, M.   Kubarovsky, A.   Kubarovsky, V   Lawrence, D.   Li, X.   Levillain, M.   Lu, H.   Ma, L.   Martel, P.   Matveev, V   McNulty, D.   Mecking, B.   Micherdzinska, A.   Milbrath, B.   Minehart, R.   Miskimen, R.   Mochalov, V   Morrison, B.   Mtingwa, S.   Nakagawa, I   Overby, S.   Pasyuk, E.   Payen, M.   Park, K.   Pedroni, R.   Phelps, W.   Protopopescu, D.   Rimal, D.   Ritchie, B. G.   Romanov, D.   Salgado, C.   Shahinyan, A.   Sitnikov, A.   Sober, D.   Stepanyan, S.   Stephens, W.   Tarasov, V   Taylor, S.   Teymurazyan, A.   Underwood, J.   Vasiliev, A.   Vishnyakov, V.   Weygand, D. P.   Wood, M.   Zhang, Y.   Zhou, S.   Zihlmann, B.  

    The cross section of atomic electron Compton scattering gamma + e -> gamma' + e' was measured in the 4.400-5.475 GeV photon beam energy region by the PrimEx collaboration at Jefferson Lab with an accuracy of 2.6% and less. The results are consistent with theoretical predictions that include next-to-leading order radiative corrections. The measurements provide the first high precision test of this elementary QED process at beam energies greater than 0.1 GeV. (C) 2019 The Author(s). Published by Elsevier B.V.
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  • Modified structure of protons and neutrons in correlated pairs

    Schmookler, B.   Duer, M.   Schmidt, A.   Hen, O.   Gilad, S.   Piasetzky, E.   Strikman, M.   Weinstein, L. B.   Adhikari, S.   Amaryan, M.   Ashkenazi, A.   Avakian, H.   Ball, J.   Balossino, I.   Barion, L.   Bashkanov, M.   Battaglieri, M.   Beck, A.   Bedlinskiy, I.   Biselli, A. S.   Boiarinov, S.   Briscoe, W. J.   Brooks, W. K.   Burkert, V. D.   Carman, D. S.   Celentano, A.   Charles, G.   Chetry, T.   Ciullo, G.   Cohen, E.   Cole, P. L.   Crede, V.   Cruz-Torres, R.   D'Angelo, A.   Dashyan, N.   De Sanctis, E.   De Vita, R.   Deur, A.   Diehl, S.   Djalali, C.   Dupre, R.   Egiyan, H.   El Fassi, L.   Elouadrhiri, L.   Eugenio, P.   Fedotov, G.   Fersch, R.   Filippi, A.   Forest, T. A.   Gavalian, G.   Gilfoyle, G. P.   Girod, F. X.   Golovatch, E.   Gothe, R. W.   Griffioen, K. A.   Guidal, M.   Guo, L.   Hafidi, K.   Hakobyan, H.   Hanretty, C.   Harrison, N.   Hauenstein, F.   Hayward, T. B.   Hicks, K.   Higinbotham, D.   Holtrop, M.   Hyde, C. E.   Ilieva, Y.   Ireland, D. G.   Ishkhanov, B. S.   Isupov, E. L.   Jo, H. -S.   Johnston, S.   Joo, K.   Joosten, S.   Kabir, M. L.   Keller, D.   Khachatryan, G.   Khachatryan, M.   Khandaker, M.   Kim, A.   Kim, W.   Klein, A.   Klein, F. J.   Korover, I.   Kubarovsky, V.   Kuhn, S. E.   Kuleshov, S. V.   Lanza, L.   Laskaris, G.   Lenisa, P.   Livingston, K.   MacGregor, I. J. D.   Markov, N.   McKinnon, B.   Beck, S. Mey-Tal   Mineeva, T.   Mirazita, M.   Mokeev, V.   Montgomery, R. A.   Camacho, C. Munoz   Mustapha, B.   Niccolai, S.   Osipenko, M.   Ostrovidov, A. I.   Paolone, M.   Paremuzyan, R.   Park, K.   Pasyuk, E.   Patsyuk, M.   Pogorelko, O.   Price, J. W.   Prok, Y.   Protopopescu, D.   Ripani, M.   Riser, D.   Rizzo, A.   Rosner, G.   Rossi, P.   Sabatie, F.   Salgado, C.   Schumacher, R. A.   Segarra, E. P.   Sharabian, G.   Skorodumina, I. U.   Sokhan, D.   Sparveris, N.   Stepanyan, S.   Strauch, S.   Taiuti, M.   Tan, J. A.   Ungaro, M.   Voskanyan, H.   Voutier, E.   Watts, D. P.   Wei, X.   Wood, M.   Zachariou, N.   Zhang, J.   Zhao, Z. W.   Zheng, X.  

    The atomic nucleus is made of protons and neutrons (nucleons), which are themselves composed of quarks and gluons. Understanding how the quark-gluon structure of a nucleon bound in an atomic nucleus is modified by the surrounding nucleons is an outstanding challenge. Although evidence for such modification-known as the EMC effect-was first observed over 35 years ago, there is still no generally accepted explanation for its cause(1-3). Recent observations suggest that the EMC effect is related to close-proximity short-range correlated (SRC) nucleon pairs in nuclei(4,5). Here we report simultaneous, high-precision measurements of the EMC effect and SRC abundances. We show that EMC data can be explained by a universal modification of the structure of nucleons in neutron-proton SRC pairs and present a data-driven extraction of the corresponding universal modification function. This implies that in heavier nuclei with many more neutrons than protons, each proton is more likely than each neutron to belong to an SRC pair and hence to have distorted quark structure. This universal modification function will be useful for determining the structure of the free neutron and thereby testing quantum chromodynamics symmetry-breaking mechanisms and may help to discriminate between nuclear physics effects and beyond-the-standard-model effects in neutrino experiments.
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  • The Jefferson Lab frozen spin target

    Keith, C. D.   Brock, J.   Carlin, C.   Comer, S. A.   Kashy, D.   McAndrew, J.   Meekins, D. G.   Pasyuk, E.   Pierce, J. J.   Seely, M. L.  

    A frozen spin polarized target, constructed at Jefferson Lab for use inside a large acceptance spectrometer, is described. The target has been utilized for photoproduction measurements with polarized tagged photons of both longitudinal and circular polarization. Protons in TEMPO-doped butanol were dynamically polarized to approximately 90% outside the spectrometer at 5 T and 200-300 mK. Photoproduction data were acquired with the target inside the spectrometer at a frozen-spin temperature of approximately 30 mK with the polarization maintained by a thin, superconducting coil installed inside the target cryostat. A 0.56 T solenoid was used for longitudinal target polarization and a 0.50 T dipole for transverse polarization. Spin-lattice relaxation times as high as 4000 h were observed. We also report polarization results for deuterated propanediol doped with the trityl radical OX063. (C) 2012 Elsevier B.V. All rights reserved.
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  • Semi-inclusive pi(0) target and beam-target asymmetries from 6 GeV electron scattering with CLAS

    Jawalkar, S.   Koirala, S.   Avakian, H.   Bosted, P.   Griffioen, K. A.   Keith, C.   Kuhn, S. E.   Adhikari, K. P.   Adhikari, S.   Adikaram, D.   Akbar, Z.   Amaryan, M. J.   Pereira, S. Anefalos   Ball, J.   Baltzell, N. A.   Battaglieri, M.   Batourine, V.   Bedlinskiy, I.   Biselli, A. S.   Boiarinov, S.   Briscoe, W. J.   Brock, J.   Brooks, W. K.   Bultmann, S.   Burkert, V. D.   Cao, Frank Thanh   Carlin, C.   Carman, D. S.   Celentano, A.   Charles, G.   Chetry, T.   Ciullo, G.   Clark, L.   Colaneri, L.   Cole, P. L.   Contalbrigo, M.   Cortes, O.   Crede, V.   D'Angelo, A.   Dashyan, N.   De Vita, R.   De Sanctis, E.   Defurne, M.   Deur, A.   Djalali, C.   Ddoge, G.   Dupre, R.   Egiyan, H.   El Alaoui, A.   El Fassi, L.   Elouadrhiri, L.   Eugenio, P.   Fedotov, G.   Fegan, S.   Fersch, R.   Filippi, A.   Fleming, J. A.   Forest, T. A.   Fradi, A.   Garcon, M.   Ghandilyan, Y.   Gilfoyle, G. P.   Giovanetti, K. L.   Girod, F. X.   Gleason, C.   Gohn, W.   Golovatch, E.   Gothe, R. W.   Guidal, M.   Guler, N.   Guo, L.   Hakobyan, H.   Hanretty, C.   Harrison, N.   Hattawy, M.   Heddle, D.   Hicks, K.   Hollis, G.   Holtrop, M.   Hughes, S. M.   Ilieva, Y.   Ireland, D. G.   Ishkhanov, B. S.   Isupov, E. L.   Jenkins, D.   Jiang, H.   Joo, K.   Joosten, S.   Keller, D.   Khachatryan, G.   Khachatryan, M.   Khandaker, M.   Kim, A.   Kim, W.   Klein, A.   Klein, F. J.   Kubarovsky, V.   Kuleshov, S. V.   Lanza, L.   Lenisa, P.   Livingston, K.   Lu, H. Y.   MacGregor, I. J. D.   Markov, N.   Mayer, M.   McCracken, M. E.   McKinnon, B.   Meyer, C. A.   Mineeva, T.   Mirazita, M.   Mokeev, V.   Montgomery, R. A.   Movsisyan, A.   Camacho, C. Munoz   Nadel-Turonski, P.   Net, L. A.   Niccolai, S.   Niculescu, G.   Niculescu, I.   Osipenko, M.   Ostrovidov, A. I.   Paremuzyan, R.   Park, K.   Pasyuk, E.   Phelps, E.   Phelps, W.   Pierce, J.   Pisano, S.   Pogorelko, O.   Price, J. W.   Prok, Y.   Protopopescu, D.   Raue, B. A.   Ripani, M.   Riser, D.   Rizzo, A.   Rosner, G.   Rossi, P.   Sabatie, F.   Salgado, C.   Schumacher, R. A.   Seder, E.   Sharabian, Y. G.   Simonyan, A.   Skorodumina, Iu.   Smith, G. D.   Sober, D. I.   Sokhan, D.   Sparveris, N.   Stankovic, I.   Strauch, S.   Taiuti, M.   Ungaro, M.   Voskanyan, H.   Voutier, E.   Walford, N. K.   Watts, D. P.   Wei, X.   Weinstein, L. B.   Wood, M. H.   Zachariou, N.   Zhang, J.   Zhao, Z. W.  

    We present precision measurements of the target and beam-target spin asymmetries from neutral pion electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized protons in a cryogenic (14)NH(3)target, and extracted double and single target spin asymmetries for ep -> e'pi(0)Xin multidimensional bins in four-momentum transfer (1.0 < Q(2) < 3.2GeV(2)), Bjorken-x(0.12 < x < 0.48), hadron energy fraction (0.4 < z < 0.7), transverse pion momentum (0 < P-T < 1.0GeV), and azimuthal angel phi(h) between the lepton scattering and hadron production planes. We extracted asymmetries as a function of both xand P-T, which provide access to transverse-momentum distributions of longitudinally polarized quarks. The double spin asymmetries depend weakly on P-T. The sin2 phi(h) moments are zero within uncertainties, which is consistent with the expected suppression of the Collins fragmentation function. The observed sin phi(h) moments suggest that quark gluon correlations are significant at large x. (C) 2018 The Authors. Published by Elsevier B.V.
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  • Photon beam asymmetry Sigma in the reaction <(gamma)over right arrow> -> p omega for E-gamma=3D1.152 to 1.876 GeV

    Collins, P.   Ritchie, B. G.   Dugger, M.   Klein, F. J.   Anisovich, A. V.   Klempt, E.   Nikonov, V. A.   Sarantsev, A.   Adhikari, K. P.   Adhikari, S.   Adikaram, D.   Akbar, Z.   Pereira, S. Anefalos   Avakian, H.   Ball, J.   Baltzell, N. A.   Bashkanov, M.   Battaglieri, M.   Batourine, V.   Bedlinskiy, I.   Biselli, A. S.   Boiarinov, S.   Briscoe, W. J.   Brooks, W. K.   Burkert, V. D.   Cao, Frank Thanh   Cao, T.   Carman, D. S.   Celentano, A.   Charles, G.   Chetry, T.   Ciullo, G.   Clark, L.   Cole, P. L.   Contalbrigo, M.   Cortes, O.   Crede, V.   Dashyan, N.   De Vita, R.   De Sanctis, E.   Defurne, M.   Deur, A.   Djalali, C.   Dupre, R.   Egiyan, H.   El Alaoui, A.   El Fassi, L.   Eugenio, P.   Fedotov, G.   Filippi, A.   Fleming, J. A.   Ghandilyan, Y.   Gilfoyle, G. P.   Giovanetti, K. L.   Girod, F. X.   Glazier, D. I.   Gleason, C.   Golovatch, E.   Gothe, R. W.   Griffioen, K. A.   Guidal, M.   Hafidi, K.   Hakobyan, H.   Hanretty, C.   Harrison, N.   Hattawy, M.   Heddle, D.   Hicks, K.   Hollis, G.   Holtrop, M.   Hughes, S. M.   Ilieva, Y.   Ireland, D. G.   Ishkhanov, B. S.   Isupov, E. L.   Jenkins, D.   Jiang, H.   Jo, H. S.   Joosten, S.   Keller, D.   Khachatryan, G.   Khachatryan, M.   Khandaker, M.   Kim, A.   Kim, W.   Klein, A.   Kubarovsky, V.   Kuleshov, S. V.   Lanza, L.   Lenisa, P.   Livingston, K.   MacGregor, I. J. D.   Markov, N.   McKinnon, B.   Meyer, C. A.   Meziani, Z. E.   Mineeva, T.   Mokeev, V.   Montgomery, R. A.   Movsisyan, A.   Munevar, E.   Camacho, C. Munoz   Nadel-Turonski, P.   Net, L. A.   Niccolai, S.   Niculescu, G.   Niculescu, I.   Osipenko, M.   Ostrovidov, A. I.   Paolone, M.   Paremuzyan, R.   Park, K.   Pasyuk, E.   Phelps, W.   Pisano, S.   Pogorelko, O.   Price, J. W.   Procureur, S.   Prok, Y.   Protopopescu, D.   Raue, B. A.   Ripani, M.   Rizzo, A.   Rosner, G.   Sabatie, F.   Salgado, C.   Schumacher, R. A.   Sharabian, Y. G.   Simonyan, A.   Skorodumina, Iu.   Smith, G. D.   Sober, D. I.   Sokhan, D.   Sparveris, N.   Stankovic, I.   Stepanyan, S.   Strakovsky, I. I.   Strauch, S.   Taiuti, M.   Ungaro, M.   Voskanyan, H.   Voutier, E.   Walford, N. K.   Watts, D. P.   Wei, X.   Wood, M. H.   Zachariou, N.   Zhang, J.   Zhao, Z. W.  

    Photon beam asymmetry Sigma measurements for omega photoproduction in the reaction gamma (gamma) over right arrow p -> omega p are reported for photon energies from 1.152 to 1.876 GeV. Data were taken using a linearly-polarized tagged photon beam, a cryogenic hydrogen target, and the CLAS spectrometer in Hall B at Jefferson Lab. The measurements obtained markedly increase the size of the database for this observable, extend coverage to higher energies, and resolve discrepancies in previously published data. Comparisons of these new results with predictions from a chiral-quark-based model and from a dynamical coupled-channels model indicate the importance of interferences between t-channel meson exchange and s- and u-channel contributions, underscoring sensitivity to the nucleon resonances included in those descriptions. Comparisons with the Bonn-Gatchina partial-wave analysis indicate the Sigma data reported here help to fix the magnitudes of the interference terms between the leading amplitudes in that calculation (Pomeron exchange and the resonant portion of the J(P)=3D 3/2(+) partial wave), as well as the resonant portions of the smaller partial waves with J(P)=3D 1/2(-), 3/2(-), and 5/2(+). (C) 2017 The Author(s). Published by Elsevier B.V.
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  • Precise measurements of beam spin asymmetries in semi-inclusive pi(0) production RID A-2439-2012 RID B-4083-2012 RID D-4072-2011

    Aghasyan, M.   Avakian, H.   Rossi, P.   De Sanctis, E.   Hasch, D.   Mirazita, M.   Adikaram, D.   Amaryan, M. J.   Anghinolfi, M.   Baghdasaryan, H.   Ball, J.   Battaglieri, M.   Batourine, V.   Bedlinskiy, I.   Bennett, R. P.   Biselli, A. S.   Branford, D.   Briscoe, W. J.   Bueltmann, S.   Burkert, V. D.   Carman, D. S.   Chandavar, S.   Cole, P. L.   Collins, P.   Contalbrigo, M.   Crede, V.   D'Angelo, A.   Daniel, A.   Dashyan, N.   De Vita, R.   Deur, A.   Dey, B.   Dickson, R.   Djalali, C.   Dodge, G. E.   Doughty, D.   Dupre, R.   Egiyan, H.   El Alaoui, A.   Elouadrhiri, L.   Eugenio, P.   Fedotov, G.   Fegan, S.   Fradi, A.   Gabrielyan, M. Y.   Garcon, M.   Gevorgyan, N.   Gilfoyle, G. P.   Giovanetti, K. L.   Girod, F. X.   Goetz, J. T.   Gohn, W.   Golovatch, E.   Gothe, R. W.   Graham, L.   Griffioen, K. A.   Guegan, B.   Guidal, M.   Guler, N.   Guo, L.   Hafidi, K.   Hanretty, C.   Hicks, K.   Holtrop, M.   Hyde, C. E.   Ilieva, Y.   Ireland, D. G.   Isupov, E. L.   Jawalkar, S. S.   Jenkins, D.   Jo, H. S.   Joo, K.   Keller, D.   Khandaker, M.   Khetarpal, P.   Kim, A.   Kim, W.   Klein, A.   Klein, F. J.   Kubarovsky, V.   Kuhn, S. E.   Kuleshov, S. V.   Kuznetsov, V.   Kvaltine, N. D.   Livingston, K.   Lu, H. Y.   MacGregor, I. J. D.   Markov, N.   Mayer, M.   McAndrew, J.   McKinnon, B.   Meyer, C. A.   Micherdzinska, A. M.   Mokeev, V.   Moreno, B.   Moutarde, H.   Munevar, E.   Nadel-Turonski, P.   Ni, A.   Niccolai, S.   Niculescu, G.   Niculescu, I.   Osipenko, M.   Ostrovidov, A. I.   Paolone, M.   Pappalardo, L.   Paremuzyan, R.   Park, K.   Park, S.   Pasyuk, E.   Pereira, S. Anefalos   Phelps, E.   Pisano, S.   Pogorelko, O.   Pozdniakov, S.   Price, J. W.   Procureur, S.   Prok, Y.   Protopopescu, D.   Raue, B. A.   Ricco, G.   Rimal, D.   Ripani, M.   Rosner, G.   Sabatie, F.   Saini, M. S.   Salgado, C.   Schott, D.   Schumacher, R. A.   Seder, E.   Seraydaryan, H.   Sharabian, Y. G.   Smith, G. D.   Sober, D. I.   Stepanyan, S. S.   Stepanyan, S.   Stoler, P.   Strakovsky, I.   Strauch, S.   Taiuti, M.   Tang, W.   Taylor, C. E.   Tkachenko, S.   Ungaro, M.   Voskanyan, H.   Voutier, E.   Watts, D.   Weinstein, L. B.   Weygand, D. P.   Wood, M. H.   Zana, L.   Zhang, J.   Zhao, B.   Zhao, Z. W.  

    We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. A substantial sin phi(h) amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle phi(h) of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations. (C) 2011 Elsevier B.V. All rights reserved.
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  • Measurement of nuclear transparency ratios for protons and neutrons

    Duer, M.   Hen, O.   Piasetzky, E.   Weinstein, L. B.   Schmidt, A.   Korover, I   Cohen, E. O.   Hakobyan, H.   Adhikari, S.   Angelini, G.   Avakian, H.   Gayoso, C. Ayerbe   Barion, L.   Battaglieri, M.   Beck, A.   Bedlinskiy, I   Biselli, A. S.   Boiarinov, S.   Briscoe, W. J.   Brooks, W.   Burkert, V. D.   Cao, F.   Carman, D. S.   Celentano, A.   Chatagnon, P.   Chetry, T.   Ciullo, G.   Cole, P. L.   Contalbrigo, M.   Cortes, O.   Crede, V   Torres, R. Cruz   D'Angelo, A.   Dashyan, N.   De Vita, R.   De Sanctis, E.   Deur, A.   Diehl, S.   Djalali, C.   Dupre, R.   Duran, Burcu   Egiyan, H.   Ehrhart, M.   El Alaoui, A.   El Fassi, L.   Eugenio, P.   Filippi, A.   Forest, T. A.   Gilfoyle, G. P.   Girod, F. X.   Golovatch, E.   Gothe, R. W.   Griffioen, K. A.   Guidal, M.   Guo, L.   Hafidi, K.   Hanretty, C.   Harrison, N.   Hattawy, M.   Hauenstein, F.   Hayward, T. B.   Heddle, D.   Holtrop, M.   Ilievaa, Y.   Ireland, D. G.   Ishkhanov, B. S.   Isupov, E. L.   Jo, H. S.   Johnston, S.   Joo, K.   Joosten, S.   Keller, D.   Khachatryan, G.   Khachatryan, M.   Khanal, A.   Khandaker, M.   Kim, A.   Kim, W.   Klein, A.   Klein, F. J.   Kubarovsky, V   Kuhn, S. E.   Kuleshov, S., V   Lanza, L.   Laskaris, G.   Lenisa, P.   Livingston, K.   MacGregor, I. J. D.   Marchand, D.   McKinnon, B.   Beck, S. Mey-Tal   Mineeva, T.   Mirazita, M.   Mokeev, V   Montgomery, R. A.   Movsisyan, A.   Camacho, C. Munoz   Mustapha, B.   Nadel-Turonski, P.   Niccolai, S.   Niculescu, G.   Osipenko, M.   Ostrovidov, A., I   Paolone, M.   Pappalardo, L. L.   Paremuzyan, R.   Pasyuk, E.   Patsyuk, M.   Payette, D.   Price, J.   Pocanic, D.   Pogorelko, O.   Prok, Y.   Protopopescu, D.   Raue, B. A.   Ripani, M.   Riser, D.   Rizzo, A.   Rosner, G.   Rossi, P.   Sabatie, F.   Salgado, C.   Schmookler, B. A.   Schumacher, R. A.   Segarra, E. P.   Sharabian, Y. G.   Skorodumina, Iu   Sokhan, D.   Soto, O.   Sparveris, N.   Stepanyan, S.   Strauch, S.   Taiuti, M.   Tan, J. A.   Ungaro, M.   Voskanyan, H.   Voutier, E.   Wang, R.   Wei, X.   Zachariou, N.   Zhang, J.   Zhao, Z. W.   Zheng, X.  

    This paper presents, for the first time, measurements of neutron transparency ratios for nuclei relative to C measured using the (e, e'n) reaction, spanning measured neutron momenta of 1.4 to 2.4 GeV/c. The transparency ratios were extracted in two kinematical regions, corresponding to knockout of mean-field nucleons and to the breakup of Short-Range Correlated nucleon pairs. The extracted neutron transparency ratios are consistent with each other for the two measured kinematical regions and agree with the proton transparencies extracted from new and previous (e, e'p) measurements, including those from neutron-rich nuclei such as lead. The data also agree with and confirm the Glauber approximation that is commonly used to interpret experimental data. The nuclear-mass-dependence of the extracted transparencies scales as A(alpha) with alpha =3D -0.289 +/- 0.007, which is consistent with nuclear-surface dominance of the reactions. (C) 2019 The Author. Published by Elsevier B.V.
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