H. C. Fenker - HKS - JLab E05-115 and E01-001 - Collaborations

H. C. Fenker
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H. C. Fenker
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HKS - JLab E05-115 and E01-001 - Collaborations
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Nuclear Experiment (29)
 
High Energy Physics - Experiment (7)
 
Physics - Instrumentation and Detectors (5)
 
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Publications Authored By H. C. Fenker

Structure functions, as measured in lepton-nucleon scattering, have proven to be very useful in studying the quark dynamics within the nucleon. However, it is experimentally difficult to separately determine the longitudinal and transverse structure functions, and consequently there are substantially less data available for the longitudinal structure function in particular. Here we present separated structure functions for hydrogen and deuterium at low four--momentum transfer squared, Q^2< 1 GeV^2, and compare these with parton distribution parameterizations and a k_T factorization approach. Read More

Background: Measurements of forward exclusive meson production at different squared four-momenta of the exchanged virtual photon, $Q^2$, and at different four-momentum transfer, t, can be used to probe QCD's transition from meson-nucleon degrees of freedom at long distances to quark-gluon degrees of freedom at short scales. Ratios of separated response functions in $\pi^-$ and $\pi^+$ electroproduction are particularly informative. The ratio for transverse photons may allow this transition to be more easily observed, while the ratio for longitudinal photons provides a crucial verification of the assumed pole dominance, needed for reliable extraction of the pion form factor from electroproduction data. Read More

2014Jun
Authors: L. Tang1, C. Chen2, T. Gogami3, D. Kawama4, Y. Han5, L. Yuan6, A. Matsumura7, Y. Okayasu8, T. Seva9, V. M. Rodriguez10, P. Baturin11, A. Acha12, P. Achenbach13, A. Ahmidouch14, I. Albayrak15, D. Androic16, A. Asaturyan17, R. Asaturyan18, O. Ates19, R. Badui20, O. K. Baker21, F. Benmokhtar22, W. Boeglin23, J. Bono24, P. Bosted25, E. Brash26, P. Carter27, R. Carlini28, A. Chiba29, M. E. Christy30, L. Cole31, M. M. Dalton32, S. Danagoulian33, A. Daniel34, R. De Leo35, V. Dharmawardane36, D. Doi37, K. Egiyan38, M. Elaasar39, R. Ent40, H. Fenker41, Y. Fujii42, M. Furic43, M. Gabrielyan44, L. Gan45, F. Garibaldi46, D. Gaskell47, A. Gasparian48, E. F. Gibson49, P. Gueye50, O. Hashimoto51, D. Honda52, T. Horn53, B. Hu54, Ed V. Hungerford55, C. Jayalath56, M. Jones57, K. Johnston58, N. Kalantarians59, H. Kanda60, M. Kaneta61, F. Kato62, S. Kato63, M. Kawai64, C. Keppel65, H. Khanal66, M. Kohl67, L. Kramer68, K. J. Lan69, Y. Li70, A. Liyanage71, W. Luo72, D. Mack73, K. Maeda74, S. Malace75, A. Margaryan76, G. Marikyan77, P. Markowitz78, T. Maruta79, N. Maruyama80, V. Maxwell81, D. J. Millener82, T. Miyoshi83, A. Mkrtchyan84, H. Mkrtchyan85, T. Motoba86, S. Nagao87, S. N. Nakamura88, A. Narayan89, C. Neville90, G. Niculescu91, M. I. Niculescu92, A. Nunez93, Nuruzzaman94, H. Nomura95, K. Nonaka96, A. Ohtani97, M. Oyamada98, N. Perez99, T. Petkovic100, J. Pochodzalla101, X. Qiu102, S. Randeniya103, B. Raue104, J. Reinhold105, R. Rivera106, J. Roche107, C. Samanta108, Y. Sato109, B. Sawatzky110, E. K. Segbefia111, D. Schott112, A. Shichijo113, N. Simicevic114, G. Smith115, Y. Song116, M. Sumihama117, V. Tadevosyan118, T. Takahashi119, N. Taniya120, K. Tsukada121, V. Tvaskis122, M. Veilleux123, W. Vulcan124, S. Wells125, F. R. Wesselmann126, S. A. Wood127, T. Yamamoto128, C. Yan129, Z. Ye130, K. Yokota131, S. Zhamkochyan132, L. Zhu133
Affiliations: 1HKS - JLab E05-115 and E01-001 - Collaborations, 2HKS - JLab E05-115 and E01-001 - Collaborations, 3HKS - JLab E05-115 and E01-001 - Collaborations, 4HKS - JLab E05-115 and E01-001 - Collaborations, 5HKS - JLab E05-115 and E01-001 - Collaborations, 6HKS - JLab E05-115 and E01-001 - Collaborations, 7HKS - JLab E05-115 and E01-001 - Collaborations, 8HKS - JLab E05-115 and E01-001 - Collaborations, 9HKS - JLab E05-115 and E01-001 - Collaborations, 10HKS - JLab E05-115 and E01-001 - Collaborations, 11HKS - JLab E05-115 and E01-001 - Collaborations, 12HKS - JLab E05-115 and E01-001 - Collaborations, 13HKS - JLab E05-115 and E01-001 - Collaborations, 14HKS - JLab E05-115 and E01-001 - Collaborations, 15HKS - JLab E05-115 and E01-001 - Collaborations, 16HKS - JLab E05-115 and E01-001 - Collaborations, 17HKS - JLab E05-115 and E01-001 - Collaborations, 18HKS - JLab E05-115 and E01-001 - Collaborations, 19HKS - JLab E05-115 and E01-001 - Collaborations, 20HKS - JLab E05-115 and E01-001 - 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Collaborations, 101HKS - JLab E05-115 and E01-001 - Collaborations, 102HKS - JLab E05-115 and E01-001 - Collaborations, 103HKS - JLab E05-115 and E01-001 - Collaborations, 104HKS - JLab E05-115 and E01-001 - Collaborations, 105HKS - JLab E05-115 and E01-001 - Collaborations, 106HKS - JLab E05-115 and E01-001 - Collaborations, 107HKS - JLab E05-115 and E01-001 - Collaborations, 108HKS - JLab E05-115 and E01-001 - Collaborations, 109HKS - JLab E05-115 and E01-001 - Collaborations, 110HKS - JLab E05-115 and E01-001 - Collaborations, 111HKS - JLab E05-115 and E01-001 - Collaborations, 112HKS - JLab E05-115 and E01-001 - Collaborations, 113HKS - JLab E05-115 and E01-001 - Collaborations, 114HKS - JLab E05-115 and E01-001 - Collaborations, 115HKS - JLab E05-115 and E01-001 - Collaborations, 116HKS - JLab E05-115 and E01-001 - Collaborations, 117HKS - JLab E05-115 and E01-001 - Collaborations, 118HKS - JLab E05-115 and E01-001 - Collaborations, 119HKS - JLab E05-115 and E01-001 - Collaborations, 120HKS - 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Since the pioneering experiment, E89-009 studying hypernuclear spectroscopy using the $(e,e^{\prime}K^+)$ reaction was completed, two additional experiments, E01-011 and E05-115, were performed at Jefferson Lab. These later experiments used a modified experimental design, the "tilt method", to dramatically suppress the large electromagnetic background, and allowed for a substantial increase in luminosity. Additionally, a new kaon spectrometer, HKS (E01-011), a new electron spectrometer, HES, and a new splitting magnet were added to produce precision, high-resolution hypernuclear spectroscopy. Read More

2014Apr
Affiliations: 1The Jefferson Lab Fpi Collaboration, 2The Jefferson Lab Fpi Collaboration, 3The Jefferson Lab Fpi Collaboration, 4The Jefferson Lab Fpi Collaboration, 5The Jefferson Lab Fpi Collaboration, 6The Jefferson Lab Fpi Collaboration, 7The Jefferson Lab Fpi Collaboration, 8The Jefferson Lab Fpi Collaboration, 9The Jefferson Lab Fpi Collaboration, 10The Jefferson Lab Fpi Collaboration, 11The Jefferson Lab Fpi Collaboration, 12The Jefferson Lab Fpi Collaboration, 13The Jefferson Lab Fpi Collaboration, 14The Jefferson Lab Fpi Collaboration, 15The Jefferson Lab Fpi Collaboration, 16The Jefferson Lab Fpi Collaboration, 17The Jefferson Lab Fpi Collaboration, 18The Jefferson Lab Fpi Collaboration, 19The Jefferson Lab Fpi Collaboration, 20The Jefferson Lab Fpi Collaboration, 21The Jefferson Lab Fpi Collaboration, 22The Jefferson Lab Fpi Collaboration, 23The Jefferson Lab Fpi Collaboration, 24The Jefferson Lab Fpi Collaboration, 25The Jefferson Lab Fpi Collaboration, 26The Jefferson Lab Fpi Collaboration, 27The Jefferson Lab Fpi Collaboration, 28The Jefferson Lab Fpi Collaboration, 29The Jefferson Lab Fpi Collaboration, 30The Jefferson Lab Fpi Collaboration, 31The Jefferson Lab Fpi Collaboration, 32The Jefferson Lab Fpi Collaboration, 33The Jefferson Lab Fpi Collaboration, 34The Jefferson Lab Fpi Collaboration, 35The Jefferson Lab Fpi Collaboration, 36The Jefferson Lab Fpi Collaboration, 37The Jefferson Lab Fpi Collaboration, 38The Jefferson Lab Fpi Collaboration, 39The Jefferson Lab Fpi Collaboration, 40The Jefferson Lab Fpi Collaboration, 41The Jefferson Lab Fpi Collaboration, 42The Jefferson Lab Fpi Collaboration, 43The Jefferson Lab Fpi Collaboration, 44The Jefferson Lab Fpi Collaboration, 45The Jefferson Lab Fpi Collaboration, 46The Jefferson Lab Fpi Collaboration, 47The Jefferson Lab Fpi Collaboration, 48The Jefferson Lab Fpi Collaboration, 49The Jefferson Lab Fpi Collaboration, 50The Jefferson Lab Fpi Collaboration, 51The Jefferson Lab Fpi Collaboration, 52The Jefferson Lab Fpi Collaboration, 53The Jefferson Lab Fpi Collaboration, 54The Jefferson Lab Fpi Collaboration, 55The Jefferson Lab Fpi Collaboration, 56The Jefferson Lab Fpi Collaboration, 57The Jefferson Lab Fpi Collaboration, 58The Jefferson Lab Fpi Collaboration, 59The Jefferson Lab Fpi Collaboration, 60The Jefferson Lab Fpi Collaboration, 61The Jefferson Lab Fpi Collaboration, 62The Jefferson Lab Fpi Collaboration, 63The Jefferson Lab Fpi Collaboration, 64The Jefferson Lab Fpi Collaboration, 65The Jefferson Lab Fpi Collaboration, 66The Jefferson Lab Fpi Collaboration, 67The Jefferson Lab Fpi Collaboration, 68The Jefferson Lab Fpi Collaboration, 69The Jefferson Lab Fpi Collaboration, 70The Jefferson Lab Fpi Collaboration, 71The Jefferson Lab Fpi Collaboration, 72The Jefferson Lab Fpi Collaboration, 73The Jefferson Lab Fpi Collaboration, 74The Jefferson Lab Fpi Collaboration, 75The Jefferson Lab Fpi Collaboration, 76The Jefferson Lab Fpi Collaboration, 77The Jefferson Lab Fpi Collaboration, 78The Jefferson Lab Fpi Collaboration, 79The Jefferson Lab Fpi Collaboration, 80The Jefferson Lab Fpi Collaboration, 81The Jefferson Lab Fpi Collaboration, 82The Jefferson Lab Fpi Collaboration, 83The Jefferson Lab Fpi Collaboration, 84The Jefferson Lab Fpi Collaboration, 85The Jefferson Lab Fpi Collaboration, 86The Jefferson Lab Fpi Collaboration, 87The Jefferson Lab Fpi Collaboration, 88The Jefferson Lab Fpi Collaboration

The study of exclusive $\pi^{\pm}$ electroproduction on the nucleon, including separation of the various structure functions, is of interest for a number of reasons. The ratio $R_L=\sigma_L^{\pi^-}/\sigma_L^{\pi^+}$ is sensitive to isoscalar contamination to the dominant isovector pion exchange amplitude, which is the basis for the determination of the charged pion form factor from electroproduction data. A change in the value of $R_T=\sigma_T^{\pi^-}/\sigma_T^{\pi^+}$ from unity at small $-t$, to 1/4 at large $-t$, would suggest a transition from coupling to a (virtual) pion to coupling to individual quarks. Read More

2014Feb
Authors: S. Tkachenko1, N. Baillie2, S. E. Kuhn3, J. Zhang4, J. Arrington5, P. Bosted6, S. Bültmann7, M. E. Christy8, D. Dutta9, R. Ent10, H. Fenker11, K. A. Griffioen12, M. Ispiryan13, N. Kalantarians14, C. E. Keppel15, W. Melnitchouk16, V. Tvaskis17, K. P. Adhikari18, M. Aghasyan19, M. J. Amaryan20, S. Anefalos Pereira21, H. Avakian22, J. Ball23, N. A. Baltzell24, M. Battaglieri25, I. Bedlinskiy26, A. S. Biselli27, W. J. Briscoe28, W. K. Brooks29, V. D. Burkert30, D. S. Carman31, A. Celentano32, S. Chandavar33, G. Charles34, P. L. Cole35, M. Contalbrigo36, O. Cortes37, V. Crede38, A. D'Angelo39, N. Dashyan40, R. De Vita41, E. De Sanctis42, A. Deur43, C. Djalali44, G. E. Dodge45, D. Doughty46, R. Dupre47, H. Egiyan48, A. El Alaoui49, L. El Fassi50, L. Elouadrhiri51, P. Eugenio52, G. Fedotov53, J. A. Fleming54, B. Garillon55, N. Gevorgyan56, Y. Ghandilyan57, G. P. Gilfoyle58, K. L. Giovanetti59, F. X. Girod60, J. T. Goetz61, E. Golovatch62, R. W. Gothe63, M. Guidal64, L. Guo65, K. Hafidi66, H. Hakobyan67, C. Hanretty68, N. Harrison69, M. Hattawy70, K. Hicks71, D. Ho72, M. Holtrop73, C . E. Hyde74, Y. Ilieva75, D. G. Ireland76, B. S. Ishkhanov77, H. S. Jo78, D. Keller79, M. Khandaker80, A. Kim81, W. Kim82, P. M. King83, A. Klein84, F. J. Klein85, S. Koirala86, V. Kubarovsky87, S. V. Kuleshov88, P. Lenisa89, S. Lewis90, K. Livingston91, H. Lu92, M. MacCormick93, I. J. D. MacGregor94, N. Markov95, M. Mayer96, B. McKinnon97, T. Mineeva98, M. Mirazita99, V. Mokeev100, R. A. Montgomery101, H. Moutarde102, C. Munoz Camacho103, P. Nadel-Turonski104, S. Niccolai105, G. Niculescu106, I. Niculescu107, M. Osipenko108, L. L. Pappalardo109, R. Paremuzyan110, K. Park111, E. Pasyuk112, J. J. Phillips113, S. Pisano114, O. Pogorelko115, S. Pozdniakov116, J. W. Price117, S. Procureur118, D. Protopopescu119, A. J . R. Puckett120, D. Rimal121, M. Ripani122, A. Rizzo123, G. Rosner124, P. Rossi125, P. Roy126, F. Sabatié127, D. Schott128, R. A. Schumacher129, E. Seder130, I. Senderovich131, Y. G. Sharabian132, A. Simonyan133, G. D. Smith134, D. I. Sober135, D. Sokhan136, S. Stepanyan137, S. S. Stepanyan138, S. Strauch139, W. Tang140, M. Ungaro141, A. V. Vlassov142, H. Voskanyan143, E. Voutier144, N. K. Walford145, D. Watts146, X. Wei147, L. B. Weinstein148, M. H. Wood149, L. Zana150, I. Zonta151
Affiliations: 1The CLAS collaboration, 2The CLAS collaboration, 3The CLAS collaboration, 4The CLAS collaboration, 5The CLAS collaboration, 6The CLAS collaboration, 7The CLAS collaboration, 8The CLAS collaboration, 9The CLAS collaboration, 10The CLAS collaboration, 11The CLAS collaboration, 12The CLAS collaboration, 13The CLAS collaboration, 14The CLAS collaboration, 15The CLAS collaboration, 16The CLAS collaboration, 17The CLAS collaboration, 18The CLAS collaboration, 19The CLAS collaboration, 20The CLAS collaboration, 21The CLAS collaboration, 22The CLAS collaboration, 23The CLAS collaboration, 24The CLAS collaboration, 25The CLAS collaboration, 26The CLAS collaboration, 27The CLAS collaboration, 28The CLAS collaboration, 29The CLAS collaboration, 30The CLAS collaboration, 31The CLAS collaboration, 32The CLAS collaboration, 33The CLAS collaboration, 34The CLAS collaboration, 35The CLAS collaboration, 36The CLAS collaboration, 37The CLAS collaboration, 38The CLAS collaboration, 39The CLAS collaboration, 40The CLAS collaboration, 41The CLAS collaboration, 42The CLAS collaboration, 43The CLAS collaboration, 44The CLAS collaboration, 45The CLAS collaboration, 46The CLAS collaboration, 47The CLAS collaboration, 48The CLAS collaboration, 49The CLAS collaboration, 50The CLAS collaboration, 51The CLAS collaboration, 52The CLAS collaboration, 53The CLAS collaboration, 54The CLAS collaboration, 55The CLAS collaboration, 56The CLAS collaboration, 57The CLAS collaboration, 58The CLAS collaboration, 59The CLAS collaboration, 60The CLAS collaboration, 61The CLAS collaboration, 62The CLAS collaboration, 63The CLAS collaboration, 64The CLAS collaboration, 65The CLAS collaboration, 66The CLAS collaboration, 67The CLAS collaboration, 68The CLAS collaboration, 69The CLAS collaboration, 70The CLAS collaboration, 71The CLAS collaboration, 72The CLAS collaboration, 73The CLAS collaboration, 74The CLAS collaboration, 75The CLAS collaboration, 76The CLAS collaboration, 77The CLAS collaboration, 78The CLAS collaboration, 79The CLAS collaboration, 80The CLAS collaboration, 81The CLAS collaboration, 82The CLAS collaboration, 83The CLAS collaboration, 84The CLAS collaboration, 85The CLAS collaboration, 86The CLAS collaboration, 87The CLAS collaboration, 88The CLAS collaboration, 89The CLAS collaboration, 90The CLAS collaboration, 91The CLAS collaboration, 92The CLAS collaboration, 93The CLAS collaboration, 94The CLAS collaboration, 95The CLAS collaboration, 96The CLAS collaboration, 97The CLAS collaboration, 98The CLAS collaboration, 99The CLAS collaboration, 100The CLAS collaboration, 101The CLAS collaboration, 102The CLAS collaboration, 103The CLAS collaboration, 104The CLAS collaboration, 105The CLAS collaboration, 106The CLAS collaboration, 107The CLAS collaboration, 108The CLAS collaboration, 109The CLAS collaboration, 110The CLAS collaboration, 111The CLAS collaboration, 112The CLAS collaboration, 113The CLAS collaboration, 114The CLAS collaboration, 115The CLAS collaboration, 116The CLAS collaboration, 117The CLAS collaboration, 118The CLAS collaboration, 119The CLAS collaboration, 120The CLAS collaboration, 121The CLAS collaboration, 122The CLAS collaboration, 123The CLAS collaboration, 124The CLAS collaboration, 125The CLAS collaboration, 126The CLAS collaboration, 127The CLAS collaboration, 128The CLAS collaboration, 129The CLAS collaboration, 130The CLAS collaboration, 131The CLAS collaboration, 132The CLAS collaboration, 133The CLAS collaboration, 134The CLAS collaboration, 135The CLAS collaboration, 136The CLAS collaboration, 137The CLAS collaboration, 138The CLAS collaboration, 139The CLAS collaboration, 140The CLAS collaboration, 141The CLAS collaboration, 142The CLAS collaboration, 143The CLAS collaboration, 144The CLAS collaboration, 145The CLAS collaboration, 146The CLAS collaboration, 147The CLAS collaboration, 148The CLAS collaboration, 149The CLAS collaboration, 150The CLAS collaboration, 151The CLAS collaboration

Much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x. Read More

2013Jul
Affiliations: 1Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 2Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 3Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 4Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 5Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 6Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 7Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 8Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 9Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 10Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 11Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 12Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 13Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 14Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 15Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 16Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 17Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 18Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 19Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 20Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 21Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 22Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 23Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, MA, USA and the Bates Research and Engineering Center, Middleton MA, 24Jefferson Lab, Newport News, VA USA, 25Jefferson Lab, Newport News, VA USA, 26Jefferson Lab, Newport News, VA USA, 27Jefferson Lab, Newport News, VA USA, 28Jefferson Lab, Newport News, VA USA, 29Jefferson Lab, Newport News, VA USA, 30Jefferson Lab, Newport News, VA USA, 31Jefferson Lab, Newport News, VA USA, 32Jefferson Lab, Newport News, VA USA, 33Jefferson Lab, Newport News, VA USA, 34Jefferson Lab, Newport News, VA USA, 35Jefferson Lab, Newport News, VA USA, 36Jefferson Lab, Newport News, VA USA, 37Jefferson Lab, Newport News, VA USA, 38Jefferson Lab, Newport News, VA USA, 39Jefferson Lab, Newport News, VA USA, 40Jefferson Lab, Newport News, VA USA, 41Jefferson Lab, Newport News, VA USA, 42Jefferson Lab, Newport News, VA USA, 43Jefferson Lab, Newport News, VA USA, 44Jefferson Lab, Newport News, VA USA, 45Jefferson Lab, Newport News, VA USA, 46Physics Dept. U.C. Berkeley, Berkeley, CA USA, 47Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD USA, 48Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD USA, 49Physics Department, Arizona State University, Tempe, 50Physics Department, Arizona State University, Tempe, 51Los Alamos National Laboratory, Los Alamos NM USA, 52Physics Dept., Hampton University, Hampton, VA and Jefferson Lab, Newport News, VA USA, 53Physics Dept., Hampton University, Hampton, VA and Jefferson Lab, Newport News, VA USA, 54Physics Dept., Hampton University, Hampton, VA and Jefferson Lab, Newport News, VA USA, 55Physics Dept., Catholic University of America, Washington, DC USA, 56Physics Dept., Catholic University of America, Washington, DC USA, 57Physics Dept., Catholic University of America, Washington, DC USA, 58Temple University, Philadelphia PA USA, 59Temple University, Philadelphia PA USA, 60Temple University, Philadelphia PA USA, 61Temple University, Philadelphia PA USA, 62Temple University, Philadelphia PA USA, 63University Bonn, Bonn Germany, 64University Bonn, Bonn Germany, 65University Bonn, Bonn Germany, 66Physikalisches Institut Justus-Liebig-Universitt Giessen, Giessen Germany, 67Physikalisches Institut Justus-Liebig-Universitt Giessen, Giessen Germany

We give a short overview of the DarkLight detector concept which is designed to search for a heavy photon A' with a mass in the range 10 MeV/c^2 < m(A') < 90 MeV/c^2 and which decays to lepton pairs. We describe the intended operating environment, the Jefferson Laboratory free electon laser, and a way to extend DarkLight's reach using A' --> invisible decays. Read More

The lifetime of a Lambda particle embedded in a nucleus (hypernucleus) decreases from that of free Lambda decay due to the opening of the Lambda N to NN weak decay channel. However, it is generally believed that the lifetime of a hypernucleus attains a constant value (saturation) for medium to heavy hypernuclear masses, yet this hypothesis has been difficult to verify. The present paper reports a direct measurement of the lifetime of medium-heavy hypernuclei produced with a photon-beam from Fe, Cu, Ag, and Bi targets. Read More

2012Jul
Affiliations: 1HKS, 2HKS, 3HKS, 4HKS, 5HKS, 6HKS, 7HKS, 8HKS, 9HKS, 10HKS, 11HKS, 12HKS, 13HKS, 14HKS, 15HKS, 16HKS, 17HKS, 18HKS, 19HKS, 20HKS, 21HKS, 22HKS, 23HKS, 24HKS, 25HKS, 26HKS, 27HKS, 28HKS, 29HKS, 30HKS, 31HKS, 32HKS, 33HKS, 34HKS, 35HKS, 36HKS, 37HKS, 38HKS, 39HKS, 40HKS, 41HKS, 42HKS, 43HKS, 44HKS, 45HKS, 46HKS, 47HKS, 48HKS, 49HKS, 50HKS, 51HKS, 52HKS, 53HKS, 54HKS, 55HKS, 56HKS, 57HKS, 58HKS, 59HKS, 60HKS, 61HKS, 62HKS, 63HKS, 64HKS, 65HKS, 66HKS, 67HKS, 68HKS, 69HKS, 70HKS, 71HKS, 72HKS, 73HKS, 74HKS, 75HKS, 76HKS, 77HKS, 78HKS, 79HKS, 80HKS, 81HKS, 82HKS, 83HKS, 84HKS, 85HKS, 86HKS, 87HKS, 88HKS, 89HKS, 90HKS, 91HKS, 92HKS, 93HKS

An experiment with a newly developed high-resolution kaon spectrometer (HKS) and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab (JLab). The ground state of a neutron-rich hypernucleus, He 7 Lambda, was observed for the first time with the (e,e'K+) reaction with an energy resolution of ~0.6 MeV. Read More

The electromagnetic calorimeters of the various magnetic spectrometers in Hall C at Jefferson Lab are presented. For the existing HMS and SOS spectrometers design considerations, relevant construction information, and comparisons of simulated and experimental results are included. The energy resolution of the HMS and SOS calorimeters is better than $\sigma/E \sim 6%/\sqrt E $, and pion/electron ($\pi/e$) separation of about 100:1 has been achieved in energy range 1 -- 5 GeV. Read More

We propose a new precision measurement of parity-violating electron scattering on the proton at very low Q^2 and forward angles to challenge predictions of the Standard Model and search for new physics. A unique opportunity exists to carry out the first precision measurement of the proton's weak charge, $Q_W =1 - 4\sin^2\theta_W$. A 2200 hour measurement of the parity violating asymmetry in elastic ep scattering at Q^2=0. Read More

2011Oct
Authors: N. Baillie, S. Tkachenko, J. Zhang, P. Bosted, S. Bultmann, M. E. Christy, H. Fenker, K. A. Griffioen, C. E. Keppel, S. E. Kuhn, W. Melnitchouk, V. Tvaskis, K. P. Adhikari, D. Adikaram, M. Aghasyan, M. J. Amaryan, M. Anghinolfini, J. Arrington, H. Avakian, H. Baghdasaryan, M. Battaglieri, A. S. Biselli, 5 D. Branford, W. J. Briscoe, W. K. Brooks, V. D. Burkert, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, P. L. Cole, M. Contalbrigo, V. Crede, A. D'Angelo, A. Daniel, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, B. Dey, C. Djalali, G. Dodge, J. Domingo, D. Doughty, R. Dupre, D. Dutta, R. Ent, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, A. Fradi, M. Y. Gabrielyan, N. Gevorgyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, W. Gohn, E. Golovatch, R. W. Gothe, L. Graham, B. Guegan, M. Guidal, N. Guler, L. Guo, K. Hafidi, D. Heddle, K. Hicks, M. Holtrop, E. Hungerford, C. E. Hyde, Y. Ilieva, D. G. Ireland, M. Ispiryan, E. L. Isupov, S. S. Jawalkar, H. S. Jo, N. Kalantarians, M. Khandaker, P. Khetarpal, A. Kim, W. Kim, P. M. King, A. Klein, F. J. Klein, A. Klimenko, V. Kubarovsky, S. V. Kuleshov, N. D. Kvaltine, K. Livingston, H. Y. Lu, I . J . D. MacGregor, Y. Mao, N. Markov, B. McKinnon, T. Mineeva, B. Morrison, H. Moutarde, E. Munevar, P. Nadel-Turonski, A. Ni, S. Niccolai, I. Niculescu, G. Niculescu, M. Osipenko, A. I. Ostrovidov, L. Pappalardo, K. Park, S. Park, E. Pasyuk, S. Anefalos Pereira, S. Pisano, S. Pozdniakov, J. W. Price, S. Procureur, Y. Prok, D. Protopopescu, B. A. Raue, G. Ricco, D. Rimal, M. Ripani, G. Rosner, P. Rossi, F. Sabatie, M. S. Saini, C. Salgado, D. Schott, R. A. Schumacher, E. Seder, Y. G. Sharabian, D. I. Sober, D. Sokhan, S. Stepanyan, S. S. Stepanyan, P. Stoler, S. Strauch, M. Taiuti, W. Tang, M. Ungaro, M. F. Vineyard, E. Voutier, D. P. Watts, L. B. Weinstein, D. P. Weygand, M. H. Wood, L. Zana, B. Zhao

We report on the first measurement of the F2 structure function of the neutron from semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to < 100 MeV and their angles to < 100 degrees relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F2n data collected cover the nucleon resonance and deep-inelastic regions over a wide range of Bjorken x for 0. Read More

We present new data for the polarization observables of the final state proton in the $^{1}H(\vec{\gamma},\vec{p})\pi^{0}$ reaction. These data can be used to test predictions based on hadron helicity conservation (HHC) and perturbative QCD (pQCD). These data have both small statistical and systematic uncertainties, and were obtained with beam energies between 1. Read More

A large set of cross sections for semi-inclusive electroproduction of charged pions ($\pi^\pm$) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared $W^2$ > 4 GeV$^2$ and range in four-momentum transfer squared $2 < Q^2 < 4$ (GeV/c)$^2$, and cover a range in the Bjorken scaling variable 0.2 < x < 0. Read More

2011Mar
Authors: G0 Collaboration, D. Androic, D. S. Armstrong, J. Arvieux, R. Asaturyan, T. D. Averett, S. L. Bailey, G. Batigne, D. H. Beck, E. J. Beise, J. Benesch, F. Benmokhtar, L. Bimbot, J. Birchall, A. Biselli, P. Bosted, H. Breuer, P. Brindza, C. L. Capuano, R. D. Carlini, R. Carr, N. Chant, Y. -C. Chao, R. Clark, A. Coppens, S. D. Covrig, A. Cowley, D. Dale, C. A. Davis, C. Ellis, W. R. Falk, H. Fenker, J. M. Finn, T. Forest, G. Franklin, R. Frascaria, C. Furget, D. Gaskell, M. T. W. Gericke, J. Grames, K. A. Griffioen, K. Grimm, G. Guillard, B. Guillon, H. Guler, K. Gustafsson, L. Hannelius, J. Hansknecht, R. D. Hasty, A. M. Hawthorne Allen, T. Horn, T. M. Ito, K. Johnston, M. Jones, P. Kammel, R. Kazimi, P. M. King, A. Kolarkar, E. Korkmaz, W. Korsch, S. Kox, J. Kuhn, J. Lachniet, R. Laszewski, L. Lee, J. Lenoble, E. Liatard, J. Liu, A. Lung, G. A. MacLachlan, J. Mammei, D. Marchand, J. W. Martin, D. J. Mack, K. W. McFarlane, D. W. McKee, R. D. McKeown, F. Merchez, M. Mihovilovic, A. Micherdzinska, H. Mkrtchyan, B. Moffit, M. Morlet, M. Muether, J. Musson, K. Nakahara, R. Neveling, S. Niccolai, D. Nilsson, S. Ong, S. A. Page, V. Papavassiliou, S. F. Pate, S. K. Phillips, P. Pillot, M. L. Pitt, M. Poelker, T. A. Porcelli, G. Quemener, B. P. Quinn, W. D. Ramsay, A. W. Rauf, J. -S. Real, T. Ries, J. Roche P. Roos, G. A. Rutledge, J. Schaub, J. Secrest, T. Seva, N. Simicevic, G. R. Smith, D. T. Spayde, S. Stepanyan, M. Stutzman, R. Suleiman, V. Tadevosyan, R. Tieulent, J. van de Wiele, W. T. H. van Oers, M. Versteegen, E. Voutier, W. F. Vulcan, S. P. Wells, G. Warren, S. E. Williamson, R. J. Woo, S. A. Wood, C. Yan, J. Yun, V. Zeps

In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. Read More

2010Dec

Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, $G_{E}/G_{M}$, obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange (TPEX) contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic $H(\vec{e},e'\vec{p})$ reaction for three different beam energies at a fixed squared momentum transfer $Q^2 = 2. Read More

We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the cross section for $x>1$, which is sensitive to short range contributions to the nuclear wave-function, and in deep inelastic scattering corresponds to probing extremely high momentum quarks. This result agrees with higher energy muon scattering measurements, but is in sharp contrast to neutrino scattering measurements which suggested a dramatic enhancement in the distribution of the `super-fast' quarks probed at x>1. Read More

2010May

Among the most fundamental observables of nucleon structure, electromagnetic form factors are a crucial benchmark for modern calculations describing the strong interaction dynamics of the nucleon's quark constituents; indeed, recent proton data have attracted intense theoretical interest. In this letter, we report new measurements of the proton electromagnetic form factor ratio using the recoil polarization method, at momentum transfers Q2=5.2, 6. Read More

2008Nov
Affiliations: 1nee Rohe, 2nee Rohe, 3nee Rohe, 4nee Rohe, 5nee Rohe, 6nee Rohe, 7nee Rohe, 8nee Rohe, 9nee Rohe, 10nee Rohe, 11nee Rohe, 12nee Rohe, 13nee Rohe, 14nee Rohe, 15nee Rohe, 16nee Rohe, 17nee Rohe, 18nee Rohe, 19nee Rohe, 20nee Rohe, 21nee Rohe, 22nee Rohe, 23nee Rohe, 24nee Rohe, 25nee Rohe, 26nee Rohe, 27nee Rohe, 28nee Rohe, 29nee Rohe, 30nee Rohe, 31nee Rohe, 32nee Rohe, 33nee Rohe, 34nee Rohe, 35nee Rohe, 36nee Rohe, 37nee Rohe, 38nee Rohe, 39nee Rohe, 40nee Rohe, 41nee Rohe, 42nee Rohe, 43nee Rohe, 44nee Rohe, 45nee Rohe, 46nee Rohe, 47nee Rohe, 48nee Rohe, 49nee Rohe, 50nee Rohe, 51nee Rohe, 52nee Rohe

We have extracted QCD matrix elements from our data on double polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element \tilde{d_2}, which arises strictly from quark- gluon interactions, to be unambiguously non zero. The data also reveal an isospin dependence of higher twist effects if we assume that the Burkhardt-Cottingham Sum rule is valid. Read More

Cross sections for the reaction ${^1}$H($e,e'\pi^+$)$n$ were measured in Hall C at Thomas Jefferson National Accelerator Facility (JLab) using the CEBAF high-intensity, continous electron beam in order to determine the charged pion form factor. Data were taken for central four-momentum transfers ranging from $Q^2$=0.60 to 2. Read More

2004Nov
Affiliations: 1Yerevan Physics Institute, 2Thomas Jefferson National Accelerator Facility, 3Thomas Jefferson National Accelerator Facility, 4Thomas Jefferson National Accelerator Facility, 5University of Regina, 6Thomas Jefferson National Accelerator Facility, 7Thomas Jefferson National Accelerator Facility, 8Yerevan Physics Institute, 9Thomas Jefferson National Accelerator Facility, 10Houston Baptist University, 11Yerevan Physics Institute, 12Yerevan Physics Institute, 13Thomas Jefferson National Accelerator Facility

We describe a new aerogel threshold Cherenkov detector installed in the HMS spectrometer in Hall C at Jefferson Lab. The Hall C experimental program in 2003 required an improved particle identification system for better identification of pi/K/P, which was achieved by installing an additional threshold Cherenkov counter. Two types of aerogel with n=1. Read More

We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 < Q^2 < 5.5 GeV^2. Read More

A pioneering experiment in Lambda hypernuclear spectroscopy, undertaken at the Thomas Jefferson National Accelerator Facility (Jlab), was recently reported. The experiment used the high- precision, continuous electron beam at Jlab, and a special arrangement of spectrometer magnets to measure the spectrum from {nat}C and 7Li targets using the (e,e' K+)reaction. The 12B hypernuclear spectrum was previously published. Read More

We have carried out an (e,e'p) experiment at high momentum transfer and in parallel kinematics to measure the strength of the nuclear spectral function S(k,E) at high nucleon momenta k and large removal energies E. This strength is related to the presence of short-range and tensor correlations, and was known hitherto only indirectly and with considerable uncertainty from the lack of strength in the independent-particle region. This experiment confirms by direct measurement the correlated strength predicted by theory. Read More