P. Solvignon - The Jefferson Lab Hall A Collaboration

P. Solvignon
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P. Solvignon
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The Jefferson Lab Hall A Collaboration
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Nuclear Experiment (44)
 
High Energy Physics - Experiment (8)
 
Nuclear Theory (7)
 
Physics - Instrumentation and Detectors (5)
 
High Energy Physics - Phenomenology (4)
 
Physics - Accelerator Physics (2)

Publications Authored By P. Solvignon

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

The charge and magnetic form factors, FC and FM, of 3He have been extracted in the kinematic range 25 fm-2 < Q2 < 61 fm-2 from elastic electron scattering by detecting 3He recoil nuclei and electrons in coincidence with the High Resolution Spectrometers of the Hall A Facility at Jefferson Lab. The measurements are indicative of a second diffraction minimum for the magnetic form factor, which was predicted in the Q2 range of this experiment, and of a continuing diffractive structure for the charge form factor. The data are in qualitative agreement with theoretical calculations based on realistic interactions and accurate methods to solve the three-body nuclear problem. Read More

We have performed a novel comparison between electron-beam polarimeters based on M{\o}ller and Compton scattering. A sequence of electron-beam polarization measurements were performed at low beam currents ($<$ 5 $\mu$A) during the $Q_{\rm weak}$ experiment in Hall C at Jefferson Lab. These low current measurements were bracketed by the regular high current (180 $\mu$A) operation of the Compton polarimeter. 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

We report on the results of the E06-014 experiment performed at Jefferson Lab in Hall A, where a precision measurement of the twist-3 matrix element $d_2$ of the neutron ($d_{2}^{n}$) was conducted. This quantity represents the average color Lorentz force a struck quark experiences in a deep inelastic electron scattering event off a neutron due to its interaction with the hadronizing remnants. This color force was determined from a linear combination of the third moments of the spin structure functions $g_1$ and $g_2$ on $^{3}$He after nuclear corrections had been applied to these moments. Read More

We report on the highest precision yet achieved in the measurement of the polarization of a low energy, $\mathcal{O}$(1 GeV), electron beam, accomplished using a new polarimeter based on electron-photon scattering, in Hall~C at Jefferson Lab. A number of technical innovations were necessary, including a novel method for precise control of the laser polarization in a cavity and a novel diamond micro-strip detector which was able to capture most of the spectrum of scattered electrons. The data analysis technique exploited track finding, the high granularity of the detector and its large acceptance. Read More

We present final results on the photon electroproduction ($\vec{e}p\rightarrow ep\gamma$) cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region from Jefferson Lab experiment E00-110. Results from an analysis of a subset of these data were published before, but the analysis has been improved which is described here at length, together with details on the experimental setup. Furthermore, additional data have been analyzed resulting in photon electroproduction cross sections at new kinematic settings, for a total of 588 experimental bins. Read More

2014Sep
Authors: Qweak Collaboration, T. Allison, M. Anderson, D. Androic, D. S. Armstrong, A. Asaturyan, T. D. Averett, R. Averill, J. Balewski, J. Beaufait, R. S. Beminiwattha, J. Benesch, F. Benmokhtar, J. Bessuille, J. Birchall, E. Bonnell, J. Bowman, P. Brindza, D. B. Brown, R. D. Carlini, G. D. Cates, B. Cavness, G. Clark, J. C. Cornejo, S. Covrig Dusa, M. M. Dalton, C. A. Davis, D. C. Dean, W. Deconinck, J. Diefenbach, K. Dow, J. F. Dowd, J. A. Dunne, D. Dutta, W. S. Duvall, J. R. Echols, M. Elaasar, W. R. Falk, K. D. Finelli, J. M. Finn, D. Gaskell, M. T. W. Gericke, J. Grames, V. M. Gray, K. Grimm, F. Guo, J. Hansknecht, D. J. Harrison, E. Henderson, J. R. Hoskins, E. Ihloff, K. Johnston, D. Jones, M. Jones, R. Jones, M. Kargiantoulakis, J. Kelsey, N. Khan, P. M. King, E. Korkmaz, S. Kowalski, A. Kubera, J. Leacock, J. P. Leckey, A. R. Lee, J. H. Lee, L. Lee, Y. Liang, S. MacEwan, D. Mack, J. A. Magee, R. Mahurin, J. Mammei, J. W. Martin, A. McCreary, M. H. McDonald, M. J. McHugh, P. Medeiros, D. Meekins, J. Mei, R. Michaels, A. Micherdzinska, A. Mkrtchyan, H. Mkrtchyan, N. Morgan, J. Musson, K. E. Mesick, A. Narayan, L. Z. Ndukum, V. Nelyubin, Nuruzzaman, W. T. H. van Oers, A. K. Opper, S. A. Page, J. Pan, K. D. Paschke, S. K. Phillips, M. L. Pitt, M. Poelker, J. F. Rajotte, W. D. Ramsay, W. R. Roberts, J. Roche, P. W. Rose, B. Sawatzky, T. Seva, M. H. Shabestari, R. Silwal, N. Simicevic, G. R. Smith, S. Sobczynski, P. Solvignon, D. T. Spayde, B. Stokes, D. W. Storey, A. Subedi, R. Subedi, R. Suleiman, V. Tadevosyan, W. A. Tobias, V. Tvaskis, E. Urban, B. Waidyawansa, P. Wang, S. P. Wells, S. A. Wood, S. Yang, S. Zhamkochyan, R. B. Zielinski

The Jefferson Lab Q_weak experiment determined the weak charge of the proton by measuring the parity-violating elastic scattering asymmetry of longitudinally polarized electrons from an unpolarized liquid hydrogen target at small momentum transfer. A custom apparatus was designed for this experiment to meet the technical challenges presented by the smallest and most precise ${\vec{e}}$p asymmetry ever measured. Technical milestones were achieved at Jefferson Lab in target power, beam current, beam helicity reversal rate, polarimetry, detected rates, and control of helicity-correlated beam properties. Read More

2014Jun
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

We have performed precision measurements of the double-spin virtual-photon asymmetry $A_1$ on the neutron in the deep inelastic scattering regime, using an open-geometry, large-acceptance spectrometer. Our data cover a wide kinematic range $0.277 \leq x \leq 0. 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

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

A subset of results from the recently completed Jefferson Lab Qweak experiment are reported. This experiment, sensitive to physics beyond the Standard Model, exploits the small parity-violating asymmetry in elastic ep scattering to provide the first determination of the protons weak charge Qweak(p). The experiment employed a 180 uA longitudinally polarized 1. Read More

The charge form factor of $^$4He has been extracted in the range 29 fm$^{-2}$ $\le Q^2 \le 77$ fm$^{-2}$ from elastic electron scattering, detecting $^4$He nuclei and electrons in coincidence with the High Resolution Spectrometers of the Hall A Facility of Jefferson Lab. The results are in qualitative agreement with realistic meson-nucleon theoretical calculations. The data have uncovered a second diffraction minimum, which was predicted in the $Q^2$ range of this experiment, and rule out conclusively long-standing predictions of dimensional scaling of high-energy amplitudes using quark counting. Read More

The Qweak experiment has measured the parity-violating asymmetry in polarized e-p elastic scattering at Q^2 = 0.025(GeV/c)^2, employing 145 microamps of 89% longitudinally polarized electrons on a 34.4cm long liquid hydrogen target at Jefferson Lab. Read More

Gas targets are often used at accelerator facilities. A design of high-pressure gas cells that are suitable for hydrogen and helium isotopes at relatively high electron beam currents is presented. In particular, we consider rare gas targets, $^3$H$_2$ and $^3$He. 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

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

2012Jun

We study the impact of the nuclear dependence of R=\sigma_L/\sigma_T on the extraction of the F_2^A/F_2^D and F_1^A/F_1^D structure function ratios from the data on the \sigma^A/\sigma^D cross section ratios. Guided by indications of the nuclear dependence of R from the world data, we examine selected sets of EMC, BCDMS, NMC and SLAC data and find that F_1^A/F_1^D < \sigma^A/\sigma^D \leq F_2^A/F_2^D. In particular, we observe that the nuclear enhancement (antishadowing) for F_1^A/F_1^D in the interval 0. Read More

Background: The density of the nucleus has been important in explaining the nuclear dependence of the quark distributions, also known as the EMC effect, as well as the presence of highmomentum nucleons arising from short-range correlations (SRCs). Recent measurements of both of these effects on light nuclei have shown a clear deviation from simple density-dependent models. Purpose: A better understanding of the nuclear quark distributions and short-range correlations requires a careful examination of the experimental data on these effects to constrain models that attempt to describe these phenomena. 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

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

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

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

Jefferson Lab experiment E01-012 measured the He-3 spin-structure functions and virtual photon asymmetries in the resonance region in the momentum transfer range 1.0Read More

The Coulomb distortion effects have been for a long time neglected in deep inelastic scattering for the good reason that the incident energies were very high. But for energies in the range of earlier data from SLAC or at JLab, the Coulomb distortion could have the potential consequence of affecting the A-dependence of the EMC effect and of the longitudinal to transverse virtual photon absorption cross section ratio $R(x,Q^2)$. Read More

An experimental study of the 16O(e,e'K^+)16N_Lambda reaction has been performed at Jefferson Lab. A thin film of falling water was used as a target. This permitted a simultaneous measurement of the p(e,e'K^+)Lambda,Sigma_0 exclusive reactions and a precise calibration of the energy scale. Read More

An experiment measuring electroproduction of hypernuclei has been performed in Hall A at Jefferson Lab on a $^{12}$C target. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a Ring Imaging CHerenkov detector (RICH) were added to the Hall A standard equipment. An unprecedented energy resolution of less than 700 keV FWHM has been achieved. Read More