W. U. Boeglin - HKS - JLab E05-115 and E01-001 - Collaborations

W. U. Boeglin
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W. U. Boeglin
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HKS - JLab E05-115 and E01-001 - Collaborations
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Nuclear Experiment (47)
 
High Energy Physics - Experiment (11)
 
Nuclear Theory (8)
 
High Energy Physics - Phenomenology (3)
 
Physics - Instrumentation and Detectors (2)
 
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Publications Authored By W. U. Boeglin

$[Background]$ Measurements of the neutron charge distribution are made difficult by the fact that, with no net charge, the neutron electric form factor, $G^n_E$, is generally much smaller than the magnetic form factor, $G^n_M$. In addition, measurements of these form factors must use nuclear targets which requires accurately accounting for nuclear effects. $[Method]$ The inclusive quasi-elastic reaction $^3\overrightarrow{\rm{He}}(\overrightarrow{e},e')$ was measured at Jefferson Lab. 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

2017Jan
Authors: GlueX Collaboration, H. Al Ghoul, E. G. Anassontzis, A. Austregesilo, F. Barbosa, A. Barnes, T. D. Beattie, D. W. Bennett, V. V. Berdnikov, T. Black, W. Boeglin, W. J. Briscoe, W. K. Brooks, B. E. Cannon, O. Chernyshov, E. Chudakov, V. Crede, M. M. Dalton, A. Deur, S. Dobbs, A. Dolgolenko, M. Dugger, R. Dzhygadlo, H. Egiyan, P. Eugenio, C. Fanelli, A. M. Foda, J. Frye, S. Furletov, L. Gan, A. Gasparian, A. Gerasimov, N. Gevorgyan, K. Goetzen, V. S. Goryachev, L. Guo, H. Hakobyan, J. Hardin, A. Henderson, G. M. Huber, D. G. Ireland, M. M. Ito, N. S. Jarvis, R. T. Jones, V. Kakoyan, M. Kamel, F. J. Klein, R. Kliemt, C. Kourkoumeli, S. Kuleshov, I. Kuznetsov, M. Lara, I. Larin, D. Lawrence, W. I. Levine, K. Livingston, G. J. Lolos, V. Lyubovitskij, D. Mack, P. T. Mattione, V. Matveev, M. McCaughan, M. McCracken, W. McGinley, J. McIntyre, R. Mendez, C. A. Meyer, R. Miskimen, R. E. Mitchell, F. Mokaya, K. Moriya, F. Nerling, G. Nigmatkulov, N. Ochoa, A. I. Ostrovidov, Z. Papandreou, M. Patsyuk, R. Pedroni, M. R. Pennington, L. Pentchev, K. J. Peters, E. Pooser, B. Pratt, Y. Qiang, J. Reinhold, B. G. Ritchie, L. Robison, D. Romanov, C. Salgado, R. A. Schumacher, C. Schwarz, J. Schwiening, A. Yu. Semenov, I. A. Semenova, K. K. Seth, M. R. Shepherd, E. S. Smith, D. I. Sober, A. Somov, S. Somov, O. Soto, N. Sparks, M. J. Staib, J. R. Stevens, I. I. Strakovsky, A. Subedi, V. Tarasov, S. Taylor, A. Teymurazyan, I. Tolstukhin, A. Tomaradze, A. Toro, A. Tsaris, G. Vasileiadis, I. Vega, N. K. Walford, D. Werthmuller, T. Whitlatch, M. Williams, E. Wolin, T. Xiao, J. Zarling, Z. Zhang, B. Zihlmann, V. Mathieu, J. Nys

We report measurements of the photon beam asymmetry $\Sigma$ for the reactions $\vec{\gamma}p\to p\pi^0$ and $\vec{\gamma}p\to p\eta $ from the GlueX experiment using a 9 GeV linearly-polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous $\pi^0$ measurements and are the first $\eta$ measurements in this energy regime. The results are compared with theoretical predictions based on $t$-channel, quasi-particle exchange and constrain the axial-vector component of the neutral meson production mechanism in these models. Read More

2016Nov
Authors: A Kirk, J Adamek, RJ Akers, S Allan, L Appel, F Arese Lucini, M Barnes, T Barrett, N Ben Ayed, W Boeglin, J Bradley, P K Browning, J Brunner, P Cahyna, M Carr, F Casson, M Cecconello, C Challis, IT Chapman, S Chapman, S Conroy, N Conway, WA Cooper, M Cox, N Crocker, B Crowley, S Cardnell, J Chorley, G Cunningham, A Danilov, D Darrow, R Dendy, D Dickinson, W Dorland, B Dudson, L Easy, S Elmore, M Evans, T Farley, N Fedorczak, A Field, I Fitzgerald, M Fox, S Freethy, L Garzotti, YC Ghim, K Gi, M Gorelenkova, W Gracias, C Gurl, W Guttenfelder, C Ham, D Harting, E Havlickova, N Hawkes, T Hender, S Henderson, J Hillesheim, B Hnat, J Horacek, J Howard, D Howell, D Dunai, G Fishpool, K Gibson, J Harrison, E Highcock, B Huang, M Inomoto, R Imazawa, O Jones, K Kadowaki, S Kaye, D Keeling, M Kocan, L Kogan, M Komm, W Lai, J Leddy, H Leggate, K Imada, I Klimek, J Hollocombe, B Lipschultz, S Lisgo, YQ Liu, B Lloyd, B Lomanowski, V Lukin, G Maddison, J Madsen, J Mailloux, R Martin, G McArdle, I Lupelli, K McClements, B McMillan, A Meakins, H Meyer, C Michael, F Militello, J Milnes, G Motojima, D Muir, G Naylor, A Nielsen, M O'Brien, M O'Mullane, J Olsen, J Omotani, Y Ono, S Pamela, AW Morris, T O'Gorman, L Pangione, F Parra, A Patel, W Peebles, R Perez, S Pinches, L Piron, M Price, M Reinke, P Ricci, F Riva, C Roach, M Romanelli, D Ryan, S Saarelma, A Saveliev, R Scannell, A Schekochihin, S Sharapov, R Sharples, V Shevchenko, K Shinohara, S Silburn, J Simpson, A Stanier, J Storrs, H Summers, Y Takase, P Tamain, H Tanabe, H Tanaka, K Tani, D Taylor, D Thomas, N Thomas-Davies, A Thornton, M Turnyanskiy, M Valovic, R Vann, F Van Wyk, N Walkden, T Watanabe, H Wilson, M Wischmeier, T Yamada, J Young, S Zoletnik, the MAST Team, the EUROfusion MST1 Team

New results from MAST are presented that focus on validating models in order to extrapolate to future devices. Measurements during start-up experiments have shown how the bulk ion temperature rise scales with the square of the reconnecting field. During the current ramp up models are not able to correctly predict the current diffusion. 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

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

2015Dec

The GlueX experiment at Jefferson Lab ran with its first commissioning beam in late 2014 and the spring of 2015. Data were collected on both plastic and liquid hydrogen targets, and much of the detector has been commissioned. All of the detector systems are now performing at or near design specifications and events are being fully reconstructed, including exclusive production of $\pi^{0}$, $\eta$ and $\omega$ mesons. Read More

We report on new p$(e,e^\prime p)\pi^\circ$ measurements at the $\Delta^{+}(1232)$ resonance at the low momentum transfer region. The mesonic cloud dynamics is predicted to be dominant and rapidly changing in this kinematic region offering a test bed for chiral effective field theory calculations. The new data explore the low $Q^2$ dependence of the resonant quadrupole amplitudes while extending the measurements of the Coulomb quadrupole amplitude to the lowest momentum transfer ever reached. Read More

The results of a comprehensive investigation into the effects of toroidicity-induced Alfv\'{e}n eigenmodes (TAE) and energetic particle modes on the NBI-generated fast-ion population in MAST plasmas are reported. Fast-ion redistribution due to frequency-chirping TAE in the range 50 kHz to 100 kHz, and frequency-chirping energetic particle modes known as fishbones in the range 20 kHz to 50 kHz, is observed. TAE and fishbones are also observed to cause losses of fast ions from the plasma. Read More

We report the first measurement of the target single-spin asymmetry, $A_y$, in quasi-elastic scattering from the inclusive reaction $^3$He$^{\uparrow}(e,e^\prime)$ on a $^3$He gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A non-zero $A_y$ can arise from the interference between the one- and two-photon exchange processes which is sensitive to the details of the sub-structure of the nucleon. Read More

We review the recent progress made in studies of deuteron structure at small internucleon distances. This progress is largely facilitated by the new generation of experiments in deuteron electrodisintegration carried out at unprecedentedly high momentum transfer. The theoretical analysis of these data confirms the onset of the high energy eikonal regime in the scattering process which allows one to separate long range nuclear effects from the effects genuinely related to the short distance structure of the deuteron. 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

A proposal approved by the Jefferson Lab (JLab) PAC to study the proton-to-neutron momentum distribution ratio in A=3 nuclei via (e,e'p) scattering off 3He and 3H mirror nuclei. The experiment will measure the 3H(e,e'p) and 3He(e,e'p) cross-sections and cross-section ratios at Q2 = 2 and xB>1 kinematics, over a missing momentum range of 0 - 450 MeV/c. The experiment was approved in 2014 at part of the JLab Hall-A Tritium run period for a total run time of 12 days. Read More

We present a precise measurement of double-polarization asymmetries in the $^3\vec{\mathrm{He}}(\vec{\mathrm{e}},\mathrm{e}'\mathrm{d})$ reaction. This particular process is a uniquely sensitive probe of hadron dynamics in $^3\mathrm{He}$ and the structure of the underlying electromagnetic currents. The measurements have been performed in and around quasi-elastic kinematics at $Q^2 = 0. Read More

We propose to enhance the kaon identification capabilities of the GlueX detector by constructing an FDIRC (Focusing Detection of Internally Reflected Cherenkov) detector utilizing the decommissioned BaBar DIRC components. The GlueX FDIRC would significantly enhance the GlueX physics program by allowing one to search for and study hybrid mesons decaying into kaon final states. Such systematic studies of kaon final states are essential for inferring the quark flavor content of hybrid and conventional mesons. 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

2014May
Affiliations: 1Jefferson Lab Hall A Collaboration, 2Jefferson Lab Hall A Collaboration, 3Jefferson Lab Hall A Collaboration, 4Jefferson Lab Hall A Collaboration, 5Jefferson Lab Hall A Collaboration, 6Jefferson Lab Hall A Collaboration, 7Jefferson Lab Hall A Collaboration, 8Jefferson Lab Hall A Collaboration, 9Jefferson Lab Hall A Collaboration, 10Jefferson Lab Hall A Collaboration, 11Jefferson Lab Hall A Collaboration, 12Jefferson Lab Hall A Collaboration, 13Jefferson Lab Hall A Collaboration, 14Jefferson Lab Hall A Collaboration, 15Jefferson Lab Hall A Collaboration, 16Jefferson Lab Hall A Collaboration, 17Jefferson Lab Hall A Collaboration, 18Jefferson Lab Hall A Collaboration, 19Jefferson Lab Hall A Collaboration, 20Jefferson Lab Hall A Collaboration, 21Jefferson Lab Hall A Collaboration, 22Jefferson Lab Hall A Collaboration, 23Jefferson Lab Hall A Collaboration, 24Jefferson Lab Hall A Collaboration, 25Jefferson Lab Hall A Collaboration, 26Jefferson Lab Hall A Collaboration, 27Jefferson Lab Hall A Collaboration, 28Jefferson Lab Hall A Collaboration, 29Jefferson Lab Hall A Collaboration, 30Jefferson Lab Hall A Collaboration, 31Jefferson Lab Hall A Collaboration, 32Jefferson Lab Hall A Collaboration, 33Jefferson Lab Hall A Collaboration, 34Jefferson Lab Hall A Collaboration, 35Jefferson Lab Hall A Collaboration, 36Jefferson Lab Hall A Collaboration, 37Jefferson Lab Hall A Collaboration, 38Jefferson Lab Hall A Collaboration, 39Jefferson Lab Hall A Collaboration, 40Jefferson Lab Hall A Collaboration, 41Jefferson Lab Hall A Collaboration, 42Jefferson Lab Hall A Collaboration, 43Jefferson Lab Hall A Collaboration, 44Jefferson Lab Hall A Collaboration, 45Jefferson Lab Hall A Collaboration, 46Jefferson Lab Hall A Collaboration, 47Jefferson Lab Hall A Collaboration, 48Jefferson Lab Hall A Collaboration, 49Jefferson Lab Hall A Collaboration, 50Jefferson Lab Hall A Collaboration, 51Jefferson Lab Hall A Collaboration, 52Jefferson Lab Hall A Collaboration, 53Jefferson Lab Hall A Collaboration, 54Jefferson Lab Hall A Collaboration, 55Jefferson Lab Hall A Collaboration, 56Jefferson Lab Hall A Collaboration, 57Jefferson Lab Hall A Collaboration, 58Jefferson Lab Hall A Collaboration, 59Jefferson Lab Hall A Collaboration, 60Jefferson Lab Hall A Collaboration, 61Jefferson Lab Hall A Collaboration, 62Jefferson Lab Hall A Collaboration, 63Jefferson Lab Hall A Collaboration, 64Jefferson Lab Hall A Collaboration, 65Jefferson Lab Hall A Collaboration, 66Jefferson Lab Hall A Collaboration, 67Jefferson Lab Hall A Collaboration, 68Jefferson Lab Hall A Collaboration, 69Jefferson Lab Hall A Collaboration, 70Jefferson Lab Hall A Collaboration, 71Jefferson Lab Hall A Collaboration, 72Jefferson Lab Hall A Collaboration, 73Jefferson Lab Hall A Collaboration, 74Jefferson Lab Hall A Collaboration, 75Jefferson Lab Hall A Collaboration, 76Jefferson Lab Hall A Collaboration, 77Jefferson Lab Hall A Collaboration, 78Jefferson Lab Hall A Collaboration, 79Jefferson Lab Hall A Collaboration, 80Jefferson Lab Hall A Collaboration, 81Jefferson Lab Hall A Collaboration, 82Jefferson Lab Hall A Collaboration, 83Jefferson Lab Hall A Collaboration, 84Jefferson Lab Hall A Collaboration, 85Jefferson Lab Hall A Collaboration, 86Jefferson Lab Hall A Collaboration, 87Jefferson Lab Hall A Collaboration, 88Jefferson Lab Hall A Collaboration, 89Jefferson Lab Hall A Collaboration, 90Jefferson Lab Hall A Collaboration, 91Jefferson Lab Hall A Collaboration, 92Jefferson Lab Hall A Collaboration, 93Jefferson Lab Hall A Collaboration, 94Jefferson Lab Hall A Collaboration, 95Jefferson Lab Hall A Collaboration, 96Jefferson Lab Hall A Collaboration, 97Jefferson Lab Hall A Collaboration, 98Jefferson Lab Hall A Collaboration

In the absence of accurate data on the free two-body hyperon-nucleon interaction, the spectra of hypernuclei can provide information on the details of the effective hyperon-nucleon interaction. Electroproduction of the hypernucleus Lambda-9Li has been studied for the first time with sub-MeV energy resolution in Hall A at Jefferson Lab on a 9Be target. In order to increase the counting rate and to provide unambiguous kaon identification, two superconducting septum magnets and a Ring Imaging CHerenkov detector (RICH) were added to the Hall A standard equipment. 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

2014Jan

We studied simultaneously the 4He(e,e'p), 4He(e,e'pp), and 4He(e,e'pn) reactions at Q^2=2 [GeV/c]2 and x_B>1, for a (e,e'p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A=2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum in a region where the nucleon-nucleon force is expected to change from predominantly tensor to repulsive. Read More

The primary motivation of the GlueX experiment is to search for and ultimately study the pattern of gluonic excitations in the meson spectrum produced in $\gamma p$ collisions. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons that have both exotic and non-exotic $J^{PC}$, corresponding to $q\bar{q}$ states ($q=u,$ $d,$ or $s$) coupled with a gluonic field. A thorough study of the hybrid spectrum, including the identification of the isovector triplet, with charges 0 and $\pm1$, and both isoscalar members, $|s\bar{s}\ >$ and $|u\bar{u}\ > + |d\bar{d}\ >$, for each predicted hybrid combination of $J^{PC}$, may only be achieved by conducting a systematic amplitude analysis of many different hadronic final states. Read More

2013Mar
Authors: I. Pomerantz1, Y. Ilieva2, R. Gilman3, D. W. Higinbotham4, E. Piasetzky5, S. Strauch6, K. P. Adhikari7, M. Aghasyan8, K. Allada9, M. J. Amaryan10, S. Anefalos Pereira11, M. Anghinolfi12, H. Baghdasaryan13, J. Ball14, N. A. Baltzell15, M. Battaglieri16, V. Batourine17, A. Beck18, S. Beck19, I. Bedlinskiy20, B. L. Berman21, A. S. Biselli22, W. Boeglin23, J. Bono24, C. Bookwalter25, S. Boiarinov26, W. J. Briscoe27, W. K. Brooks28, N. Bubis29, V. Burkert30, A. Camsonne31, M. Canan32, D. S. Carman33, A. Celentano34, S. Chandavar35, G. Charles36, K. Chirapatpimol37, E. Cisbani38, P. L. Cole39, M. Contalbrigo40, V. Crede41, F. Cusanno42, A. D'Angelo43, A. Daniel44, N. Dashyan45, C. W. de Jager46, R. De Vita47, E. De Sanctis48, A. Deur49, C. Djalali50, G. E. Dodge51, D. Doughty52, R. Dupre53, C. Dutta54, H. Egiyan55, A. El Alaoui56, L. El Fassi57, P. Eugenio58, G. Fedotov59, S. Fegan60, J. A. Fleming61, A. Fradi62, F. Garibaldi63, O. Geagla64, N. Gevorgyan65, K. L. Giovanetti66, F. X. Girod67, J. Glister68, J. T. Goetz69, W. Gohn70, E. Golovatch71, R. W. Gothe72, K. A. Griffioen73, B. Guegan74, M. Guidal75, L. Guo76, K. Hafidi77, H. Hakobyan78, N. Harrison79, D. Heddle80, K. Hicks81, D. Ho82, M. Holtrop83, C. E. Hyde84, D. G. Ireland85, B. S. Ishkhanov86, E. L. Isupov87, X. Jiang88, H. S. Jo89, K. Joo90, A. T. Katramatou91, D. Keller92, M. Khandaker93, P. Khetarpal94, E. Khrosinkova95, A. Kim96, W. Kim97, F. J. Klein98, S. Koirala99, A. Kubarovsky100, V. Kubarovsky101, S. V. Kuleshov102, N. D. Kvaltine103, B. Lee104, J. J. LeRose105, S. Lewis106, R. Lindgren107, K. Livingston108, H. Y. Lu109, I. J. D. MacGregor110, Y. Mao111, D. Martinez112, M. Mayer113, E. McCullough114, B. McKinnon115, D. Meekins116, C. A. Meyer117, R. Michaels118, T. Mineeva119, M. Mirazita120, B. Moffit121, V. Mokeev122, R. A. Montgomery123, H. Moutarde124, E. Munevar125, C. Munoz Camacho126, P. Nadel-Turonski127, R. Nasseripour128, C. S. Nepali129, S. Niccolai130, G. Niculescu131, I. Niculescu132, M. Osipenko133, A. I. Ostrovidov134, L. L. Pappalardo135, R. Paremuzyan136, K. Park137, S. Park138, G. G. Petratos139, E. Phelps140, S. Pisano141, O. Pogorelko142, S. Pozdniakov143, S. Procureur144, D. Protopopescu145, A. J. R. Puckett146, X. Qian147, Y. Qiang148, G. Ricco149, D. Rimal150, M. Ripani151, B. G. Ritchie152, I. Rodriguez153, G. Ron154, G. Rosner155, P. Rossi156, F. Sabatie157, A. Saha158, M. S. Saini159, A. J. Sarty160, B. Sawatzky161, N. A. Saylor162, D. Schott163, E. Schulte164, R. A. Schumacher165, E. Seder166, H. Seraydaryan167, R. Shneor168, G. D. Smith169, D. Sokhan170, N. Sparveris171, S. S. Stepanyan172, S. Stepanyan173, P. Stoler174, R. Subedi175, V. Sulkosky176, M. Taiuti177, W. Tang178, C. E. Taylor179, S. Tkachenko180, M. Ungaro181, B. Vernarsky182, M. F. Vineyard183, H. Voskanyan184, E. Voutier185, N. K. Walford186, Y. Wang187, D. P. Watts188, L. B. Weinstein189, D. P. Weygand190, B. Wojtsekhowski191, M. H. Wood192, X. Yan193, H. Yao194, N. Zachariou195, X. Zhan196, J. Zhang197, Z. W. Zhao198, X. Zheng199, I. Zonta200
Affiliations: 1The CLAS and Hall-A Collaborations, 2The CLAS and Hall-A Collaborations, 3The CLAS and Hall-A Collaborations, 4The CLAS and Hall-A Collaborations, 5The CLAS and Hall-A Collaborations, 6The CLAS and Hall-A Collaborations, 7The CLAS and Hall-A Collaborations, 8The CLAS and Hall-A Collaborations, 9The CLAS and Hall-A Collaborations, 10The CLAS and Hall-A Collaborations, 11The CLAS and Hall-A Collaborations, 12The CLAS and Hall-A Collaborations, 13The CLAS and Hall-A Collaborations, 14The CLAS and Hall-A Collaborations, 15The CLAS and Hall-A Collaborations, 16The CLAS and Hall-A Collaborations, 17The CLAS and Hall-A Collaborations, 18The CLAS and Hall-A Collaborations, 19The CLAS and Hall-A Collaborations, 20The CLAS and Hall-A Collaborations, 21The CLAS and Hall-A Collaborations, 22The CLAS and Hall-A Collaborations, 23The CLAS and Hall-A Collaborations, 24The CLAS and Hall-A Collaborations, 25The CLAS and Hall-A Collaborations, 26The CLAS and Hall-A Collaborations, 27The CLAS and Hall-A Collaborations, 28The CLAS and Hall-A Collaborations, 29The CLAS and Hall-A Collaborations, 30The CLAS and Hall-A Collaborations, 31The CLAS and Hall-A Collaborations, 32The CLAS and Hall-A Collaborations, 33The CLAS and Hall-A Collaborations, 34The CLAS and Hall-A Collaborations, 35The CLAS and Hall-A Collaborations, 36The CLAS and Hall-A Collaborations, 37The CLAS and Hall-A Collaborations, 38The CLAS and Hall-A Collaborations, 39The CLAS and Hall-A Collaborations, 40The CLAS and Hall-A Collaborations, 41The CLAS and Hall-A Collaborations, 42The CLAS and Hall-A Collaborations, 43The CLAS and Hall-A Collaborations, 44The CLAS and Hall-A Collaborations, 45The CLAS and Hall-A Collaborations, 46The CLAS and Hall-A Collaborations, 47The CLAS and Hall-A Collaborations, 48The CLAS and Hall-A Collaborations, 49The CLAS and Hall-A Collaborations, 50The CLAS and Hall-A Collaborations, 51The CLAS and Hall-A Collaborations, 52The CLAS and Hall-A Collaborations, 53The CLAS and Hall-A Collaborations, 54The CLAS and Hall-A Collaborations, 55The CLAS and Hall-A Collaborations, 56The CLAS and Hall-A Collaborations, 57The CLAS and Hall-A Collaborations, 58The CLAS and Hall-A Collaborations, 59The CLAS and Hall-A Collaborations, 60The CLAS and Hall-A Collaborations, 61The CLAS and Hall-A Collaborations, 62The CLAS and Hall-A Collaborations, 63The CLAS and Hall-A Collaborations, 64The CLAS and Hall-A Collaborations, 65The CLAS and Hall-A Collaborations, 66The CLAS and Hall-A Collaborations, 67The CLAS and Hall-A Collaborations, 68The CLAS and Hall-A Collaborations, 69The CLAS and Hall-A Collaborations, 70The CLAS and Hall-A Collaborations, 71The CLAS and Hall-A Collaborations, 72The CLAS and Hall-A Collaborations, 73The CLAS and Hall-A Collaborations, 74The CLAS and Hall-A Collaborations, 75The CLAS and Hall-A Collaborations, 76The CLAS and Hall-A Collaborations, 77The CLAS and Hall-A Collaborations, 78The CLAS and Hall-A Collaborations, 79The CLAS and Hall-A 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Collaborations, 106The CLAS and Hall-A Collaborations, 107The CLAS and Hall-A Collaborations, 108The CLAS and Hall-A Collaborations, 109The CLAS and Hall-A Collaborations, 110The CLAS and Hall-A Collaborations, 111The CLAS and Hall-A Collaborations, 112The CLAS and Hall-A Collaborations, 113The CLAS and Hall-A Collaborations, 114The CLAS and Hall-A Collaborations, 115The CLAS and Hall-A Collaborations, 116The CLAS and Hall-A Collaborations, 117The CLAS and Hall-A Collaborations, 118The CLAS and Hall-A Collaborations, 119The CLAS and Hall-A Collaborations, 120The CLAS and Hall-A Collaborations, 121The CLAS and Hall-A Collaborations, 122The CLAS and Hall-A Collaborations, 123The CLAS and Hall-A Collaborations, 124The CLAS and Hall-A Collaborations, 125The CLAS and Hall-A Collaborations, 126The CLAS and Hall-A Collaborations, 127The CLAS and Hall-A Collaborations, 128The CLAS and Hall-A Collaborations, 129The CLAS and Hall-A Collaborations, 130The CLAS and Hall-A Collaborations, 131The 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Collaborations, 157The CLAS and Hall-A Collaborations, 158The CLAS and Hall-A Collaborations, 159The CLAS and Hall-A Collaborations, 160The CLAS and Hall-A Collaborations, 161The CLAS and Hall-A Collaborations, 162The CLAS and Hall-A Collaborations, 163The CLAS and Hall-A Collaborations, 164The CLAS and Hall-A Collaborations, 165The CLAS and Hall-A Collaborations, 166The CLAS and Hall-A Collaborations, 167The CLAS and Hall-A Collaborations, 168The CLAS and Hall-A Collaborations, 169The CLAS and Hall-A Collaborations, 170The CLAS and Hall-A Collaborations, 171The CLAS and Hall-A Collaborations, 172The CLAS and Hall-A Collaborations, 173The CLAS and Hall-A Collaborations, 174The CLAS and Hall-A Collaborations, 175The CLAS and Hall-A Collaborations, 176The CLAS and Hall-A Collaborations, 177The CLAS and Hall-A Collaborations, 178The CLAS and Hall-A Collaborations, 179The CLAS and Hall-A Collaborations, 180The CLAS and Hall-A Collaborations, 181The CLAS and Hall-A Collaborations, 182The CLAS and Hall-A Collaborations, 183The CLAS and Hall-A Collaborations, 184The CLAS and Hall-A Collaborations, 185The CLAS and Hall-A Collaborations, 186The CLAS and Hall-A Collaborations, 187The CLAS and Hall-A Collaborations, 188The CLAS and Hall-A Collaborations, 189The CLAS and Hall-A Collaborations, 190The CLAS and Hall-A Collaborations, 191The CLAS and Hall-A Collaborations, 192The CLAS and Hall-A Collaborations, 193The CLAS and Hall-A Collaborations, 194The CLAS and Hall-A Collaborations, 195The CLAS and Hall-A Collaborations, 196The CLAS and Hall-A Collaborations, 197The CLAS and Hall-A Collaborations, 198The CLAS and Hall-A Collaborations, 199The CLAS and Hall-A Collaborations, 200The CLAS and Hall-A Collaborations

We have measured cross sections for the gamma+3He->p+d reaction at photon energies of 0.4 - 1.4 GeV and a center-of-mass angle of 90 deg. Read More

The five-fold differential cross section for the 12C(e,e'p)11B reaction was determined over a missing momentum range of 200-400 MeV/c, in a kinematics regime with Bjorken x > 1 and Q2 = 2.0 (GeV/c)2. A comparison of the results and theoretical models and previous lower missing momentum data is shown. 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

The primary motivation of the GlueX experiment is to search for and ultimately study the pattern of gluonic excitations in the meson spectrum produced in gamma p collisions. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons that have both exotic and non-exotic JPC, corresponding to q q-bar (q=u, d, or s) states coupled with a gluonic field. A thorough study of the hybrid spectrum, including the identification of the isovector triplet, with charges 0 and +-1, and both isoscalar members, |s s-bar> and |u u-bar> + |d d-bar>, for each predicted hybrid combination of JPC, may only be achieved by conducting a systematic amplitude analysis of many different hadronic final states. Read More

2012Aug
Authors: The HAPPEX, PREX Collaborations, :, S. Abrahamyan, A. Acha, A. Afanasev, Z. Ahmed, H. Albataineh, K. Aniol, D. S. Armstrong, W. Armstrong, J. Arrington, T. Averett, B. Babineau, S. L. Bailey, J. Barber, A. Barbieri, A. Beck, V. Bellini, R. Beminiwattha, H. Benaoum, J. Benesch, F. Benmokhtar, P. Bertin, T. Bielarski, W. Boeglin, P. Bosted, F. Butaru, E. Burtin, J. Cahoon, A. Camsonne, M. Canan, P. Carter, C. C. Chang, G. D. Cates, Y. C. Chao, C. Chen, J. P. Chen, Seonho Choi, E. Chudakov, E. Cisbani, B. Craver, F. Cusanno, M. M. Dalton, R. De Leo, K. de Jager, W. Deconinck, P. Decowski, D. Deepa, X. Deng, A. Deur, D. Dutta, A. Etile, C. Ferdi, R. J. Feuerbach, J. M. Finn, D. Flay, G. B. Franklin, M. Friend, S. Frullani, E. Fuchey, S. A. Fuchs, K. Fuoti, F. Garibaldi, E. Gasser, R. Gilman, A. Giusa, A. Glamazdin, L. E. Glesener, J. Gomez, M. Gorchtein, J. Grames, K. Grimm, C. Gu, O. Hansen, J. Hansknecht, O. Hen, D. W. Higinbotham, R. S. Holmes, T. Holmstrom, C. J. Horowitz, J. Hoskins, J. Huang, T. B. Humensky, C. E. Hyde, H. Ibrahim, F. Itard, C. M. Jen, E. Jensen, X. Jiang, G. Jin, S. Johnston, J. Katich, L. J. Kaufman, A. Kelleher, K. Kliakhandler, P. M. King, A. Kolarkar, S. Kowalski, E. Kuchina, K. S. Kumar, L. Lagamba, D. Lambert, P. LaViolette, J. Leacock, J. Leckey IV, J. H. Lee, J. J. LeRose, D. Lhuillier, R. Lindgren, N. Liyanage, N. Lubinsky, J. Mammei, F. Mammoliti, D. J. Margaziotis, P. Markowitz, M. Mazouz, K. McCormick, A. McCreary, D. McNulty, D. G. Meekins, L. Mercado, Z. E. Meziani, R. W. Michaels, M. Mihovilovic, B. Moffit, P. Monaghan, N. Muangma, C. Munoz-Camacho, S. Nanda, V. Nelyubin, D. Neyret, Nuruzzaman, Y. Oh, K. Otis, A. Palmer, D. Parno, K. D. Paschke, S. K. Phillips, M. Poelker, R. Pomatsalyuk, M. Posik, M. Potokar, K. Prok, A. J. R. Puckett, X. Qian, Y. Qiang, B. Quinn, A. Rakhman, P. E. Reimer, B. Reitz, S. Riordan, J. Roche, P. Rogan, G. Ron, G. Russo, K. Saenboonruang, A. Saha, B. Sawatzky, A. Shahinyan, R. Silwal, J. Singh, S. Sirca, K. Slifer, R. Snyder, P. Solvignon, P. A. Souder, M. L. Sperduto, R. Subedi, M. L. Stutzman, R. Suleiman, V. Sulkosky, C. M. Sutera, W. A. Tobias, W. Troth, G. M. Urciuoli, P. Ulmer, A. Vacheret, E. Voutier, B. Waidyawansa, D. Wang, K. Wang, J. Wexler, A. Whitbeck, R. Wilson, B. Wojtsekhowski, X. Yan, H. Yao, Y. Ye, Z. Ye, V. Yim, L. Zana, X. Zhan, J. Zhang, Y. Zhang, X. Zheng, V. Ziskin, P. Zhu

We have measured the beam-normal single-spin asymmetry $A_n$ in the elastic scattering of 1-3 GeV transversely polarized electrons from $^1$H and for the first time from $^4$He, $^{12}$C, and $^{208}$Pb. For $^1$H, $^4$He and $^{12}$C, the measurements are in agreement with calculations that relate $A_n$ to the imaginary part of the two-photon exchange amplitude including inelastic intermediate states. Surprisingly, the $^{208}$Pb result is significantly smaller than the corresponding prediction using the same formalism. Read More

2012May
Authors: H. Fonvieille1, G. Laveissiere2, N. Degrande3, S. Jaminion4, C. Jutier5, L. Todor6, R. Di Salvo7, L. Van Hoorebeke8, L. C. Alexa9, B. D. Anderson10, K. A. Aniol11, K. Arundell12, G. Audit13, L. Auerbach14, F. T. Baker15, M. Baylac16, J. Berthot17, P. Y. Bertin18, W. Bertozzi19, L. Bimbot20, W. U. Boeglin21, E. J. Brash22, V. Breton23, H. Breuer24, E. Burtin25, J. R. Calarco26, L. S. Cardman27, C. Cavata28, C. -C. Chang29, J. -P. Chen30, E. Chudakov31, E. Cisbani32, D. S. Dale33, C. W. deJager34, R. De Leo35, A. Deur36, N. d'Hose37, G. E. Dodge38, J. J. Domingo39, L. Elouadrhiri40, M. B. Epstein41, L. A. Ewell42, J. M. Finn43, K. G. Fissum44, G. Fournier45, B. Frois46, S. Frullani47, C. Furget48, H. Gao49, J. Gao50, F. Garibaldi51, A. Gasparian52, S. Gilad53, R. Gilman54, A. Glamazdin55, C. Glashausser56, J. Gomez57, V. Gorbenko58, P. Grenier59, P. A. M. Guichon60, J. O. Hansen61, R. Holmes62, M. Holtrop63, C. Howell64, G. M. Huber65, C. E. Hyde66, S. Incerti67, M. Iodice68, J. Jardillier69, M. K. Jones70, W. Kahl71, S. Kato72, A. T. Katramatou73, J. J. Kelly74, S. Kerhoas75, A. Ketikyan76, M. Khayat77, K. Kino78, S. Kox79, L. H. Kramer80, K. S. Kumar81, G. Kumbartzki82, M. Kuss83, A. Leone84, J. J. LeRose85, M. Liang86, R. A. Lindgren87, N. Liyanage88, G. J. Lolos89, R. W. Lourie90, R. Madey91, K. Maeda92, S. Malov93, D. M. Manley94, C. Marchand95, D. Marchand96, D. J. Margaziotis97, P. Markowitz98, J. Marroncle99, J. Martino100, K. McCormick101, J. McIntyre102, S. Mehrabyan103, F. Merchez104, Z. E. Meziani105, R. Michaels106, G. W. Miller107, J. Y. Mougey108, S. K. Nanda109, D. Neyret110, E. A. J. M. Offermann111, Z. Papandreou112, B. Pasquini113, C. F. Perdrisat114, R. Perrino115, G. G. Petratos116, S. Platchkov117, R. Pomatsalyuk118, D. L. Prout119, V. A. Punjabi120, T. Pussieux121, G. Quemener122, R. D. Ransome123, O. Ravel124, J. S. Real125, F. Renard126, Y. Roblin127, D. Rowntree128, G. Rutledge129, P. M. Rutt130, A. Saha131, T. Saito132, A. J. Sarty133, A. Serdarevic134, T. Smith135, G. Smirnov136, K. Soldi137, P. Sorokin138, P. A. Souder139, R. Suleiman140, J. A. Templon141, T. Terasawa142, R. Tieulent143, E. Tomasi-Gustaffson144, H. Tsubota145, H. Ueno146, P. E. Ulmer147, G. M. Urciuoli148, M. Vanderhaeghen149, R. L. J. Van der Meer150, R. Van De Vyver151, P. Vernin152, B. Vlahovic153, H. Voskanyan154, E. Voutier155, J. W. Watson156, L. B. Weinstein157, K. Wijesooriya158, R. Wilson159, B. B. Wojtsekhowski160, D. G. Zainea161, W. -M. Zhang162, J. Zhao163, Z. -L. Zhou164
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 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Jefferson Lab Hall A Collaboration, 143The Jefferson Lab Hall A Collaboration, 144The Jefferson Lab Hall A Collaboration, 145The Jefferson Lab Hall A Collaboration, 146The Jefferson Lab Hall A Collaboration, 147The Jefferson Lab Hall A Collaboration, 148The Jefferson Lab Hall A Collaboration, 149The Jefferson Lab Hall A Collaboration, 150The Jefferson Lab Hall A Collaboration, 151The Jefferson Lab Hall A Collaboration, 152The Jefferson Lab Hall A Collaboration, 153The Jefferson Lab Hall A Collaboration, 154The Jefferson Lab Hall A Collaboration, 155The Jefferson Lab Hall A Collaboration, 156The Jefferson Lab Hall A Collaboration, 157The Jefferson Lab Hall A Collaboration, 158The Jefferson Lab Hall A Collaboration, 159The Jefferson Lab Hall A Collaboration, 160The Jefferson Lab Hall A Collaboration, 161The Jefferson Lab Hall A Collaboration, 162The Jefferson Lab Hall A Collaboration, 163The Jefferson Lab Hall A Collaboration, 164The Jefferson Lab Hall A Collaboration

Virtual Compton Scattering (VCS) on the proton has been studied at Jefferson Lab using the exclusive photon electroproduction reaction (e p --> e p gamma). This paper gives a detailed account of the analysis which has led to the determination of the structure functions P_LL-P_TT/epsilon and P_LT, and the electric and magnetic generalized polarizabilities (GPs) alpha_E(Q^2) and beta_M(Q^2) at values of the four-momentum transfer squared Q^2= 0.92 and 1. Read More

2012Jan
Authors: S. Abrahamyan, Z. Ahmed, H. Albataineh, K. Aniol, D. S. Armstrong, W. Armstrong, T. Averett, B. Babineau, A. Barbieri, V. Bellini, R. Beminiwattha, J. Benesch, F. Benmokhtar, T. Bielarski, W. Boeglin, A. Camsonne, M. Canan, P. Carter, G. D. Cates, C. Chen, J. -P. Chen, O. Hen, F. Cusanno, M. M. Dalton, R. De Leo, K. de Jager, W. Deconinck, P. Decowski, X. Deng, A. Deur, D. Dutta, A. Etile, D. Flay, G. B. Franklin, M. Friend, S. Frullani, E. Fuchey, F. Garibaldi, E. Gasser, R. Gilman, A. Giusa, A. Glamazdin, J. Gomez, J. Grames, C. Gu, O. Hansen, J. Hansknecht, D. W. Higinbotham, R. S. Holmes, T. Holmstrom, C. J. Horowitz, J. Hoskins, J. Huang, C. E. Hyde, F. Itard, C. -M. Jen, E. Jensen, G. Jin, S. Johnston, A. Kelleher, K. Kliakhandler, P. M. King, S. Kowalski, K. S. Kumar, J. Leacock, J. Leckey IV, J. H. Lee, J. J. LeRose, R. Lindgren, N. Liyanage, N. Lubinsky, J. Mammei, F. Mammoliti, D. J. Margaziotis, P. Markowitz, A. McCreary, D. McNulty, L. Mercado, Z. -E. Meziani, R. W. Michaels, M. Mihovilovic, N. Muangma, C. Muñoz-Camacho, S. Nanda, V. Nelyubin, N. Nuruzzaman, Y. Oh, A. Palmer, D. Parno, K. D. Paschke, S. K. Phillips, B. Poelker, R. Pomatsalyuk, M. Posik, A. J. R. Puckett, B. Quinn, A. Rakhman, P. E. Reimer, S. Riordan, P. Rogan, G. Ron, G. Russo, K. Saenboonruang, A. Saha, B. Sawatzky, A. Shahinyan, R. Silwal, S. Sirca, K. Slifer, P. Solvignon, P. A. Souder, M. L. Sperduto, R. Subedi, R. Suleiman, V. Sulkosky, C. M. Sutera, W. A. Tobias, W. Troth, G. M. Urciuoli, B. Waidyawansa, D. Wang, J. Wexler, R. Wilson, B. Wojtsekhowski, X. Yan, H. Yao, Y. Ye, Z. Ye, V. Yim, L. Zana, X. Zhan, J. Zhang, Y. Zhang, X. Zheng, P. Zhu

We report the first measurement of the parity-violating asymmetry A_PV in the elastic scattering of polarized electrons from 208Pb. A_PV is sensitive to the radius of the neutron distribution (Rn). The result A_PV = 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

The d(e,e'p) cross section at a momentum transfer of 3.5 (GeV/c)^2 was measured over a kinematical range that made it possible to study this reaction for a set of fixed missing momenta as a function of the neutron recoil angle theta_nq and to extract missing momentum distributions for fixed values of theta_nq up to 0.55 GeV/c. Read More

We present an updated extraction of the proton electromagnetic form factor ratio, mu_p G_E/G_M, at low Q^2. The form factors are sensitive to the spatial distribution of the proton, and precise measurements can be used to constrain models of the proton. An improved selection of the elastic events and reduced background contributions yielded a small systematic reduction in the ratio mu_p G_E/G_M compared to the original analysis. 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

2010Aug
Authors: S. Riordan, S. Abrahamyan, B. Craver, A. Kelleher, A. Kolarkar, J. Miller, G. D. Cates, N. Liyanage, B. Wojtsekhowski, A. Acha, K. Allada, B. Anderson, K. A. Aniol, J. R. M. Annand, J. Arrington, T. Averett, A. Beck, M. Bellis, W. Boeglin, H. Breuer, J. R. Calarco, A. Camsonne, J. P. Chen, E. Chudakov, L. Coman, B. Crowe, F. Cusanno, D. Day, P. Degtyarenko, P. A. M. Dolph, C. Dutta, C. Ferdi, C. Fernandez-Ramirez, R. Feuerbach, L. M. Fraile, G. Franklin, S. Frullani, S. Fuchs, F. Garibaldi, N. Gevorgyan, R. Gilman, A. Glamazdin, J. Gomez, K. Grimm, J. O. Hansen, J. L. Herraiz, D. W. Higinbotham, R. Holmes, T. Holmstrom, D. Howell, C. W. deJager, X. Jiang, M. K. Jones, J. Katich, L. J. Kaufman, M. Khandaker, J. J. Kelly, D. Kiselev, W. Korsch, J. LeRose, R. Lindgren, P. Markowitz, D. J. Margaziotis, S. May-Tal Beck, S. Mayilyan, K. McCormick, Z. E. Meziani, R. Michaels, B. Moffit, S. Nanda, V. Nelyubin, T. Ngo, D. M. Nikolenko, B. Norum, L. Pentchev, C. F. Perdrisat, E. Piasetzky, R. Pomatsalyuk, D. Protopopescu, A. J. R. Puckett, V. A. Punjabi, X. Qian, Y. Qiang, B. Quinn, I. Rachek, R. D. Ransome, P. E. Reimer, B. Reitz, J. Roche, G. Ron, O. Rondon, G. Rosner, A. Saha, M. Sargsian, B. Sawatzky, J. Segal, M. Shabestari, A. Shahinyan, Yu. Shestakov, J. Singh, S. Sirca, P. Souder, S. Stepanyan, V. Stibunov, V. Sulkosky, S. Tajima, W. A. Tobias, J. M. Udias, G. M. Urciuoli, B. Vlahovic, H. Voskanyan, K. Wang, F. R. Wesselmann, J. R. Vignote, S. A. Wood, J. Wright, H. Yao, X. Zhu

The electric form factor of the neutron was determined from studies of the reaction He3(e,e'n)pp in quasi-elastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. 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

High precision measurements of induced and transferred recoil proton polarization in d(polarized gamma, polarized p})n have been performed for photon energies of 277--357 MeV and theta_cm = 20 degrees -- 120 degrees. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. At the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon-nucleon potential being used. Read More

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, where a proton is knocked-out of the nucleus with high momentum transfer and high missing momentum, show that in 12C the neutron-proton pairs are nearly twenty times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars. 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