R. Ent - HKS - JLab E05-115 and E01-001 - Collaborations

R. Ent
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R. Ent
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HKS - JLab E05-115 and E01-001 - Collaborations
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Nuclear Experiment (42)
 
High Energy Physics - Experiment (16)
 
High Energy Physics - Phenomenology (8)
 
Nuclear Theory (7)
 
Physics - Instrumentation and Detectors (5)
 
Physics - Accelerator Physics (3)

Publications Authored By R. Ent

This workshop aimed at producing an optimized photon source concept with potential increase of scientific output at Jefferson Lab, and at refining the science for hadron physics experiments benefitting from such a high-intensity photon source. The workshop brought together the communities directly using such sources for photo-production experiments, or for conversion into $K_L$ beams. The combination of high precision calorimetry and high intensity photon sources greatly enhances scientific benefit to (deep) exclusive processes like wide-angle and time-like Compton scattering. Read More

The proton is composed of quarks and gluons, bound by the most elusive mechanism of strong interaction called confinement. In this work, the dynamics of quarks and gluons are investigated using deeply virtual Compton scattering (DVCS): produced by a multi-GeV electron, a highly virtual photon scatters off the proton which subsequently radiates a high energy photon. Similarly to holography, measuring not only the magnitude but also the phase of the DVCS amplitude allows to perform 3D images of the internal structure of the proton. Read More

2017Feb
Affiliations: 1The Jefferson Lab Hall A Collaboration, 2The Jefferson Lab Hall A Collaboration, 3The Jefferson Lab Hall A Collaboration, 4The Jefferson Lab Hall A Collaboration, 5The Jefferson Lab Hall A Collaboration, 6The Jefferson Lab Hall A Collaboration, 7The Jefferson Lab Hall A Collaboration, 8The Jefferson Lab Hall A Collaboration, 9The Jefferson Lab Hall A Collaboration, 10The Jefferson Lab Hall A Collaboration, 11The Jefferson Lab Hall A Collaboration, 12The Jefferson Lab Hall A Collaboration, 13The Jefferson Lab Hall A Collaboration, 14The Jefferson Lab Hall A Collaboration, 15The Jefferson Lab Hall A Collaboration, 16The Jefferson Lab Hall A Collaboration, 17The Jefferson Lab Hall A Collaboration, 18The Jefferson Lab Hall A Collaboration, 19The Jefferson Lab Hall A Collaboration, 20The Jefferson Lab Hall A Collaboration, 21The Jefferson Lab Hall A Collaboration, 22The Jefferson Lab Hall A Collaboration, 23The Jefferson Lab Hall A Collaboration, 24The Jefferson Lab Hall A Collaboration, 25The Jefferson Lab Hall A Collaboration, 26The Jefferson Lab Hall A Collaboration, 27The Jefferson Lab Hall A Collaboration, 28The Jefferson Lab Hall A Collaboration, 29The Jefferson Lab Hall A Collaboration, 30The Jefferson Lab Hall A Collaboration, 31The Jefferson Lab Hall A Collaboration, 32The Jefferson Lab Hall A Collaboration, 33The Jefferson Lab Hall A Collaboration, 34The Jefferson Lab Hall A Collaboration, 35The Jefferson Lab Hall A Collaboration, 36The Jefferson Lab Hall A Collaboration, 37The Jefferson Lab Hall A Collaboration, 38The Jefferson Lab Hall A Collaboration, 39The Jefferson Lab Hall A Collaboration, 40The Jefferson Lab Hall A Collaboration, 41The Jefferson Lab Hall A Collaboration, 42The Jefferson Lab Hall A Collaboration, 43The Jefferson Lab Hall A Collaboration, 44The Jefferson Lab Hall A Collaboration, 45The Jefferson Lab Hall A Collaboration, 46The Jefferson Lab Hall A Collaboration, 47The Jefferson Lab Hall A Collaboration, 48The Jefferson Lab Hall A Collaboration, 49The Jefferson Lab Hall A Collaboration, 50The Jefferson Lab Hall A Collaboration, 51The Jefferson Lab Hall A Collaboration, 52The Jefferson Lab Hall A Collaboration, 53The Jefferson Lab Hall A Collaboration, 54The Jefferson Lab Hall A Collaboration, 55The Jefferson Lab Hall A Collaboration, 56The Jefferson Lab Hall A Collaboration, 57The Jefferson Lab Hall A Collaboration, 58The Jefferson Lab Hall A Collaboration, 59The Jefferson Lab Hall A Collaboration, 60The Jefferson Lab Hall A Collaboration, 61The Jefferson Lab Hall A Collaboration, 62The Jefferson Lab Hall A Collaboration, 63The Jefferson Lab Hall A Collaboration, 64The Jefferson Lab Hall A Collaboration, 65The Jefferson Lab Hall A Collaboration, 66The Jefferson Lab Hall A Collaboration, 67The Jefferson Lab Hall A Collaboration, 68The Jefferson Lab Hall A Collaboration, 69The Jefferson Lab Hall A Collaboration, 70The Jefferson Lab Hall A Collaboration, 71The Jefferson Lab Hall A Collaboration, 72The Jefferson Lab Hall A Collaboration, 73The Jefferson Lab Hall A Collaboration, 74The Jefferson Lab Hall A Collaboration, 75The Jefferson Lab Hall A Collaboration, 76The Jefferson Lab Hall A Collaboration, 77The Jefferson Lab Hall A Collaboration, 78The Jefferson Lab Hall A Collaboration, 79The Jefferson Lab Hall A Collaboration, 80The Jefferson Lab Hall A Collaboration, 81The Jefferson Lab Hall A Collaboration, 82The Jefferson Lab Hall A Collaboration, 83The Jefferson Lab Hall A Collaboration, 84The Jefferson Lab Hall A Collaboration, 85The Jefferson Lab Hall A Collaboration, 86The Jefferson Lab Hall A Collaboration, 87The Jefferson Lab Hall A Collaboration, 88The Jefferson Lab Hall A Collaboration, 89The Jefferson Lab Hall A Collaboration, 90The Jefferson Lab Hall A Collaboration, 91The Jefferson Lab Hall A Collaboration, 92The Jefferson Lab Hall A Collaboration, 93The Jefferson Lab Hall A Collaboration, 94The Jefferson Lab Hall A Collaboration, 95The Jefferson Lab Hall A Collaboration, 96The Jefferson Lab Hall A Collaboration, 97The Jefferson Lab Hall A Collaboration, 98The Jefferson Lab Hall A Collaboration

We report the first longitudinal/transverse separation of the deeply virtual exclusive $\pi^0$ electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions $d\sigma_L/dt$, $d\sigma_T/dt$, $d\sigma_{LT}/dt$ and $d\sigma_{TT}/dt$ are extracted as a function of the momentum transfer to the recoil system at $Q^2$=1.75 GeV$^2$ and $x_B$=0. Read More

We present deeply virtual $\pi^0$ electroproduction cross-section measurements at $x_B$=0.36 and three different $Q^2$--values ranging from 1.5 to 2 GeV$^2$, obtained from experiment E07-007 that ran in the Hall A at Jefferson Lab. Read More

Hadronic reactions producing strange quarks such as exclusive or semi-inclusive kaon production, play an important role in studies of hadron structure and the dynamics that bind the most basic elements of nuclear physics. The small-angle capability of the new Super High Momentum Spectrometer (SHMS) in Hall C, coupled with its high momentum reach - up to the anticipated 11-GeV beam energy in Hall C - and coincidence capability with the well-understood High Momentum Spectrometer, will allow for probes of such hadron structure involving strangeness down to the smallest distance scales to date. To cleanly select the kaons, a threshold aerogel Cerenkov detector has been constructed for the SHMS. Read More

2016Jun
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

The missing mass spectroscopy of the $^{7}_{\Lambda}$He hypernucleus was performed, using the $^{7}$Li$(e,e^{\prime}K^{+})^{7}_{\Lambda}$He reaction at the Thomas Jefferson National Accelerator Facility Hall C. The $\Lambda$ binding energy of the ground state (1/2$^{+}$) was determined with a smaller error than that of the previous measurement, being $B_{\Lambda}$ = 5.55 $\pm$ 0. Read More

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

We have determined the structure function ratio $R^d_{\rm EMC}=F_2^d/(F_2^n+F_2^p)$ from recently published $F_2^n/F_2^d$ data taken by the BONuS experiment using CLAS at Jefferson Lab. This ratio deviates from unity, with a slope $dR_{\rm EMC}^{d}/dx= -0.10\pm 0. Read More

This document summarizes the design of Jefferson Lab's electron-ion collider, MEIC, as of January 20, 2015, and describes the facility whose cost was estimated for the United States Department of Energy Nuclear Sciences Advisory Committee EIC cost review of January 26-28, 2015. In particular, each of the main technical systems within the collider is presented to the level of the best current information. Read More

Using data from the recent BONuS experiment at Jefferson Lab, which utilized a novel spectator tagging technique to extract the inclusive electron-free neutron scattering cross section, we obtain the first direct observation of quark-hadron duality in the neutron F_2 structure function. The data are used to reconstruct the lowest few (N=2, 4 and 6) moments of F_2 in the three prominent nucleon resonance regions, as well as the moments integrated over the entire resonance region. Comparison with moments computed from global parametrizations of parton distribution functions suggest that quark--hadron duality holds locally for the neutron in the second and third resonance regions down to Q^2 ~ 1 GeV^2, with violations possibly up to 20% observed in the first resonance region. 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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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

These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 6, on Accelerator Capabilities, discusses the future progress of accelerator technology, including issues for high-energy hadron and lepton colliders, high-intensity beams, electron-ion colliders, and necessary R&D for future accelerator technologies. 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

This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics and, in particular, the focused ten-week program on "Gluons and quark sea at high energies" at the Institute for Nuclear Theory in Fall 2010. 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

This white paper summarizes the scientific opportunities for utilization of the upgraded 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) and associated experimental equipment at Jefferson Lab. It is based on the 52 proposals recommended for approval by the Jefferson Lab Program Advisory Committee.The upgraded facility will enable a new experimental program with substantial discovery potential to address important topics in nuclear, hadronic, and electroweak physics. 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

2011Aug
Authors: D. Boer, M. Diehl, R. Milner, R. Venugopalan, W. Vogelsang, A. Accardi, E. Aschenauer, M. Burkardt, R. Ent, V. Guzey, D. Hasch, K. Kumar, M. A. C. Lamont, Y. Li, W. J. Marciano, C. Marquet, F. Sabatie, M. Stratmann, F. Yuan, S. Abeyratne, S. Ahmed, C. Aidala, S. Alekhin, M. Anselmino, H. Avakian, A. Bacchetta, J. Bartels, H. BC, J. Beebe-Wang, S. Belomestnykh, I. Ben-Zvi, G. Beuf, J. Blumlein, M . Blaskiewicz, A. Bogacz, S. J. Brodsky, T. Burton, R. Calaga, X. Chang, I. O. Cherednikov, P. Chevtsov, G. A. Chirilli, C. Ciofi degli Atti, I. C. Cloet, A. Cooper-Sarkar, R. Debbe, Ya. Derbenev, A. Deshpande, F. Dominguez, A. Dumitru, R. Dupre, B. Erdelyi, C. Faroughy, S. Fazio, A. Fedotov, J. R. Forshaw, R. Geraud, K. Gallmeister, L. Gamberg, J. -H. Gao, D. Gassner, F. Gelis, G. P. Gilfoyle, G. Goldstein, K. Golec-Biernat, V. P. Goncalves, M. Gonderinger, M. Guzzi, P. Hagler, H. Hahn, L. Hammons, Y. Hao, P. He, T. Horn, W. A. Horowitz, M. Huang, A. Hutton, B. Jager, W. Jackson, A. Jain, E. C. Johnson, Z. -B. Kang, L. P. Kaptari, D. Kayran, J. Kewisch, Y. Koike, A. Kondratenko, B. Z. Kopeliovich, Y. V. Kovchegov, G. Krafft, P. Kroll, S. Kumano, K. Kumericki, T. Lappi, T. Lautenschlager, R. Li, Z. -T. Liang, V. N. Litvinenko, S. Liuti, Y. Luo, D. Muller, G. Mahler, A. Majumder, S. Manikonda, F. Marhauser, G. McIntyre, M. Meskauskas, W. Meng, A. Metz, C. B. Mezzetti, G. A. Miller, M. Minty, S. -O. Moch, V. Morozov, U. Mosel, L. Motyka, H. Moutarde, P. J. Mulders, B. Musch, P. Nadel-Turonski, P. Nadolsky, F. Olness, P. N. Ostrumov, B. Parker, B. Pasquini, K. Passek-Kumericki, A. Pikin, F. Pilat, B. Pire, H. Pirner, C. Pisano, E. Pozdeyev, A. Prokudin, V. Ptitsyn, X. Qian, J. -W. Qiu, M. Radici, A. Radyushkin, T. Rao, R. Rimmer, F. Ringer, S. Riordan, T. Rogers, J. Rojo, T. Roser, R. Sandapen, R. Sassot, T. Satogata, H. Sayed, A. Schafer, G. Schnell, P. Schweitzer, B. Sheehy, J. Skaritka, G. Soyez, M. Spata, H. Spiesberger, A. M. Stasto, N. G. Stefanis, M. Strikman, M. Sullivan, L. Szymanowski, K. Tanaka, S. Taneja, S. Tepikian, B. Terzic, Y. Than, T. Toll, D. Trbojevic, E. Tsentalovich, N. Tsoupas, K. Tuchin, J. Tuozzolo, T. Ullrich, A. Vossen, S. Wallon, G. Wang, H. Wang, X. -N. Wang, S. Webb, C. Weiss, Q. Wu, B. -W. Xiao, W. Xu, B. Yunn, A. Zelenski, Y. Zhang, J. Zhou, P. Zurita

This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics. This report is organized around four major themes: i) the spin and flavor structure of the proton, ii) three-dimensional structure of nucleons and nuclei in momentum and configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and the search for physics beyond the Standard Model. 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

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

For the session on future facilities at DIS09 discussions were organized on DIS related measurements that can be expected in the near and medium - or perhaps far - future, including plans from JLab, CERN and FNAL fixed target experiments, possible measurements and detector upgrades at RHIC, as well as the plans for possible future electron proton/ion colliders such as the EIC and the LHeC project. 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

The charged pion form factor, Fpi(Q^2), is an important quantity which can be used to advance our knowledge of hadronic structure. However, the extraction of Fpi from data requires a model of the 1H(e,e'pi+)n reaction, and thus is inherently model dependent. Therefore, a detailed description of the extraction of the charged pion form factor from electroproduction data obtained recently at Jefferson Lab is presented, with particular focus given to the dominant uncertainties in this procedure. Read More

2008Sep
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

A search was made for sub-threshold $J/\psi$ production from a carbon target using a mixed real and quasi-real Bremsstrahlung photon beam with an endpoint energy of 5.76 GeV. No events were observed, which is consistent with predictions assuming quasi-free production. Read More