W. F. Vulcan

Publications (24)58.96 Total impact

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  Available from: John Robert Arrington

  Article: New measurements of high-momentum nucleons and short-range structures in nuclei.

  N Fomin, J Arrington, R Asaturyan, F Benmokhtar, W Boeglin, P Bosted, A Bruell, M H S Bukhari, M E Christy, E Chudakov, [......], L Tang, G Testa, R Trojer, V Tvaskis, W F Vulcan, C Wasko, F R Wesselmann, S A Wood, J Wright, X Zheng
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  ABSTRACT: We present new measurements of electron scattering from high-momentum nucleons in nuclei. These data allow an improved determination of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data also include the kinematic region where three-nucleon correlations are expected to dominate.
  Physical Review Letters 03/2012; 108(9):092502. · 7.37 Impact Factor
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  Available from: John Robert Arrington

  Article: Nuclear transparency and effective kaon-nucleon cross section from the A(e, e'K+) reaction

  Nuruzzaman, D Dutta, J. Arrington, R. Asaturyan, F. Benmokhtar, W. Boeglin, P. Bosted, A. Bruell, B. Clasie, M. E. Christy, [......], G R Smith, M. Sumihama, V. Tadevosyan, L Tang, V. Tvaskis, W. F. Vulcan, F. R. Wesselmann, S. A. Wood, L Yuan, X. C. Zheng
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  ABSTRACT: We have determined the transparency of the nuclear medium to kaons from $A(e,e^{'} K^{+})$ measurements on $^{12}$C, $^{63}$Cu, and $^{197}$Au targets. The measurements were performed at the Jefferson Laboratory and span a range in four-momentum-transfer squared Q$^2$=1.1 -- 3.0 GeV$^2$. The nuclear transparency was defined as the ratio of measured kaon electroproduction cross sections with respect to deuterium, ($\sigma^{A}/\sigma^{D}$). We further extracted the atomic number ($A$) dependence of the transparency as parametrized by $T= (A/2)^{\alpha-1}$ and, within a simple model assumption, the in-medium effective kaon-nucleon cross sections. The effective cross sections extracted from the electroproduction data are found to be smaller than the free cross sections determined from kaon-nucleon scattering experiments, and the parameter $\alpha$ was found to be significantly larger than those obtained from kaon-nucleus scattering. We have included similar comparisons between pion- and proton-nucleon effective cross sections as determined from electron scattering experiments, and pion-nucleus and proton-nucleus scattering data.
  03/2011;
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  Available from: John Robert Arrington

  Article: Semi-inclusive charged-pion electroproduction off protons and deuterons: Cross sections, ratios, and access to the quark-parton model at low energies

  R. Asaturyan, R. Ent, H. Mkrtchyan, T. Navasardyan, V. Tadevosyan, G. S. Adams, A. Ahmidouch, T. Angelescu, J. Arrington, A. Asaturyan, [......], A. Villano, W. F. Vulcan, M. Wang, G. Warren, F. R. Wesselmann, B. Wojtsekhowski, S. A. Wood, C. Xu, L. Yuan, X. Zheng
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  ABSTRACT: A large set of cross sections for semi-inclusive electroproduction of charged pions (π±) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W2>4 GeV2 (up to ≈7 GeV2) and range in four-momentum transfer squared 2<Q2<4 (GeV/c)2, and cover a range in the Bjorken scaling variable 0.2<x<0.6. The fractional energy of the pions spans a range 0.3<z<1, with small transverse momenta with respect to the virtual-photon direction, Pt2<0.2 (GeV/c)2. The invariant mass that goes undetected, Mx or W′, is in the nucleon resonance region, W′<2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark→pion production mechanisms. The x, z, and Pt2 dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for π+ and π−) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of d quarks are found to be slightly smaller than for u quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.
  Phys. Rev. C. 03/2011; 85(1).
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  Available from: R. Frascaria

  Article: The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles

  Collaboration, D. Androic, D. S. Armstrong, J. Arvieux, R. Asaturyan, T. D. Averett, S L Bailey, G. Batigne, D. H. Beck, E. J. Beise, [......], E. Voutier, W. F. Vulcan, S.P. Wells, G. Warren, S. E. Williamson, R. J. Woo, S. A. Wood, C Yan, J Yun, V. Zeps
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  ABSTRACT: In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. The overall design and performance of this experimental system is discussed.
  03/2011;
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  Available from: John Robert Arrington

  Article: Scaling of the F2 structure function in nuclei and quark distributions at x>1.

  N Fomin, J Arrington, D B Day, D Gaskell, A Daniel, J Seely, R Asaturyan, F Benmokhtar, W Boeglin, B Boillat, [......], L Tang, G Testa, R Trojer, V Tvaskis, W F Vulcan, C Wasko, F R Wesselmann, S A Wood, J Wright, X Zheng
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  ABSTRACT: 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 "superfast" quarks probed at x>1. The falloff at x>1 is noticeably stronger in 2H and 3He, but nearly identical for all heavier nuclei.
  Physical Review Letters 11/2010; 105(21):212502. · 7.37 Impact Factor
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  Available from: John Robert Arrington

  Article: Experimental study of the A(e,e′π+) reaction on 1H, 2H, 12C, 27Al, 63Cu, and 197Au

  X. Qian, T. Horn, B. Clasie, J. Arrington, R. Asaturyan, F. Benmokhtar, W. Boeglin, P. Bosted, A. Bruell, M. E. Christy, [......], G. R. Smith, M. Sumihama, V. Tadevosyan, L. Tang, A. Villano, W. F. Vulcan, F. R. Wesselmann, S. A. Wood, L. Yuan, X. Zheng
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  ABSTRACT: Cross sections for the 1H(e,e′π+)n process on 1H, 2H, 12C, 27Al, 63Cu, and 197Au targets were measured at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) to extract nuclear transparencies. Data were taken from Q2=1.1–4.7 GeV2 for a fixed center-of-mass energy of W=2.14 GeV. The ratio of σL and σT was extracted from the measured cross sections for 1H, 2H, 12C, and 63Cu targets at Q2=2.15 and 4.0 GeV2, allowing for additional studies of the reaction mechanism. In this article, we present the experimental setup and the analysis of the data in detail, including systematic uncertainty studies. Differential cross sections and nuclear transparencies as a function of the pion momentum at different values of Q2 are presented. Our results are consistent with the predicted early onset of color transparency in mesons. Global features of the data are discussed and the data are compared with model calculations for the 1H(e,e′π+)n reaction from nuclear targets.
  Phys. Rev. C. 05/2010; 81(5).
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  Available from: John Robert Arrington

  Article: New measurements of the European Muon Collaboration effect in very light nuclei.

  J Seely, A Daniel, D Gaskell, J Arrington, N Fomin, P Solvignon, R Asaturyan, F Benmokhtar, W Boeglin, B Boillat, [......], L Tang, G Testa, R Trojer, V Tvaskis, W F Vulcan, F R Wesselmann, S A Wood, J Wright, L Yuan, X Zheng
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  ABSTRACT: New Jefferson Lab data are presented on the nuclear dependence of the inclusive cross section from (2)H, (3)He, (4)He, (9)Be and (12)C for 0.3 < x < 0.9, Q(2) approximately 3-6 GeV(2). These data represent the first measurement of the EMC effect for (3)He at large x and a significant improvement for (4)He. The data do not support previous A-dependent or density-dependent fits to the EMC effect and suggest that the nuclear dependence of the quark distributions may depend on the local nuclear environment.
  Physical Review Letters 11/2009; 103(20):202301. · 7.37 Impact Factor
• Article: Applications of quark-hadron duality in the F2 structure function

  S. P. Malace, G. S. Adams, A. Ahmidouch, T. Angelescu, J. Arrington, R. Asaturyan, O. K. Baker, N. Benmouna, H. P. Blok, W. U. Boeglin, [......], M. Ungaro, A. Uzzle, S. Vidakovic, A. N. Villano, W. F. Vulcan, F. R. Wesselmann, B. Wojtsekhowski, S. A. Wood, L. Yuan, X. Zheng
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  ABSTRACT: Inclusive electron-proton and electron-deuteron inelastic cross sections have been measured at Jefferson Lab (JLab) in the resonance region, at large Bjorken x, up to 0.92, and four-momentum transfer squared Q2 up to 7.5 GeV2 in the experiment E00-116. These measurements are used to extend to larger x and Q2 precision, quantitative, studies of the phenomenon of quark-hadron duality. Our analysis confirms, both globally and locally, the apparent “violation” of quark-hadron duality previously observed at a Q2 of 3.5 GeV2 when resonance data are compared to structure function data created from CTEQ6M and MRST2004 parton distribution functions (PDFs). More importantly, our new data show that this discrepancy saturates by Q2~4 GeV2, becoming Q2 independent. This suggests only small violations of Q2 evolution by contributions from the higher-twist terms in the resonance region that is confirmed by our comparisons to ALEKHIN and ALLM97. We conclude that the unconstrained strength of the CTEQ6M and MRST2004 PDFs at large x is the major source of the disagreement between data and these parametrizations in the kinematic regime we study and that, in view of quark-hadron duality, properly averaged resonance region data could be used in global quantum chromodynamics fits to reduce PDF uncertainties at large x.
  Phys. Rev. C. 09/2009; 80(3).
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  Available from: John Robert Arrington

  Article: New measurements of the EMC effect in very light nuclei

  J. Seely, A Daniel, D. Gaskell, J. Arrington, N. Fomin, P Solvignon, R. Asaturyan, F. Benmokhtar, W. Boeglin, B Boillat, [......], L Tang, G. Testa, R. Trojer, V. Tvaskis, W. F. Vulcan, F. R. Wesselmann, S. A. Wood, J Wright, L Yuan, X Zheng
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  ABSTRACT: New Jefferson Lab data are presented on the nuclear dependence of the inclusive cross section from 2H, 3He, 4He, 9Be and 12C for 0.3<x<0.9, Q^2 approximately 3-6 GeV^2. These data represent the first measurement of the EMC effect for 3He at large x and a significant improvement for 4He. The data do not support previous A-dependent or density-dependent fits to the EMC effect and suggest that the nuclear dependence of the quark distributions may depend on the local nuclear environment. Comment: 5 pages, 4 figures, submitted to PRL. fixed error in author list, minor text revision
  04/2009;
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  Available from: Kawtar Hafidi

  Article: Electroproduction of Eta Mesons in the S11(1535) Resonance Region at High Momentum Transfer

  M. M. Dalton, G. S. Adams, A. Ahmidouch, T Angelescu, J. Arrington, R. Asaturyan, O.K. Baker, N Benmouna, C. Bertoncini, W. U. Boeglin, [......], W. F. Vulcan, M Wang, G. Warren, F. R. Wesselmann, B Wojtsekhowski, S. A. Wood, C Xu, L Yuan, X Zheng, H Zhu
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  ABSTRACT: The differential cross-section for the process p(e,e'p)eta has been measured at Q2 ~ 5.7 and 7.0 (GeV/c)2 for centre-of-mass energies from threshold to 1.8 GeV, encompassing the S11(1535) resonance, which dominates the channel. This is the highest momentum transfer measurement of this exclusive process to date. The helicity-conserving transition amplitude A_1/2, for the production of the S11(1535) resonance, is extracted from the data. Within the limited Q2 now measured, this quantity appears to begin scaling as 1/Q3 - a predicted, but not definitive, signal of the dominance of perturbative QCD, at Q2 ~ 5 (GeV/c)2. Comment: LaTeX, 30 pages, 29 figures, uses longtable.sty, slashbox.sty, ifthen.sty; (v2) corrected figure inclusions; (v3) changes in filenames for prc and added Report-no; (v4) correction based on comments from referee {small changes to abstract and conclusion, inserted figure 9, other small changes to the text} (v5) very minor additions to improve clarity
  04/2008;
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  Available from: Wim Cosyn

  Article: Measurement of nuclear transparency for the A(e,e'pi+) reaction.

  B Clasie, X Qian, J Arrington, R Asaturyan, F Benmokhtar, W Boeglin, P Bosted, A Bruell, M E Christy, E Chudakov, [......], M Sumihama, V Tadevosyan, L Tang, V Tvaskis, A Villano, W F Vulcan, F R Wesselmann, S A Wood, L Yuan, X C Zheng
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  ABSTRACT: We have measured the nuclear transparency of the A(e,e'pi+) process in 2H, 12C, 27Al, 63Cu, and 197Au targets. These measurements were performed at the Jefferson Laboratory over a four momentum transfer squared range Q2=1.1 to 4.7 (GeV/c)2. The nuclear transparency was extracted as the super-ratio of (sigmaA/sigmaH) from data to a model of pion-electroproduction from nuclei without pi-N final-state interactions. The Q2 and atomic number dependence of the nuclear transparency both show deviations from traditional nuclear physics expectations and are consistent with calculations that include the quantum chromodynamical phenomenon of color transparency.
  Physical Review Letters 01/2008; 99(24):242502. · 7.37 Impact Factor
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  Available from: Kawtar Hafidi

  Article: Transverse momentum dependence of semi-inclusive pion production

  H. Mkrtchyan, P. E. Bosted, G. S. Adams, A. Ahmidouch, T Angelescu, J. Arrington, R. Asaturyan, O.K. Baker, N Benmouna, C. Bertoncini, [......], W. F. Vulcan, M Wang, G. Warren, F. Wesselmann, B Wojtsekhowski, S. A. Wood, C Xu, L Yuan, X Zheng, H Zhu
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  ABSTRACT: Cross sections for semi-inclusive electroproduction of charged pions ($\pi^{\pm}$) from both proton and deuteron targets were measured for $0.2<x<0.5$, $2<Q^2<4$ GeV$^2$, $0.3<z<1$, and $P_t^2<0.2$ GeV$^2$. For $P_t<0.1$ GeV, we find the azimuthal dependence to be small, as expected theoretically. For both $\pi^+$ and $\pi^-$, the $P_t$ dependence from the deuteron is found to be slightly weaker than from the proton. In the context of a simple model, this implies that the initial transverse momenta width of $d$ quarks is larger than for $u$ quarks and, contrary to expectations, the transverse momentum width of the favored fragmentation function is larger than the unfavored one.
  10/2007;
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  Available from: John Robert Arrington

  Article: Longitudinal-transverse separations of deep-inelastic structure functions at low Q2 for hydrogen and deuterium.

  V Tvaskis, M E Christy, J Arrington, R Asaturyan, O K Baker, H P Blok, P Bosted, M Boswell, A Bruell, A Cochran, [......], G Smith, K Spurlock, G van der Steenhoven, S Stepanyan, V Tadevosian, A Uzzle, W F Vulcan, S A Wood, B Zihlmann, V Ziskin
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  ABSTRACT: We report on a study of the longitudinal to transverse cross section ratio, R=sigmaL/sigmaT, at low values of x and Q2, as determined from inclusive inelastic electron-hydrogen and electron-deuterium scattering data from Jefferson Laboratory Hall C spanning the four-momentum transfer range 0.06<Q2<2.8 GeV2. Even at the lowest values of Q2, R remains nearly constant and does not disappear with decreasing Q2, as might be expected. We find a nearly identical behavior for hydrogen and deuterium.
  Physical Review Letters 04/2007; 98(14):142301. · 7.37 Impact Factor
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  Available from: Kawtar Hafidi

  Article: Onset of quark-hadron duality in pion electroproduction.

  T Navasardyan, G S Adams, A Ahmidouch, T Angelescu, J Arrington, R Asaturyan, O K Baker, N Benmouna, C Bertoncini, H P Blok, [......], W F Vulcan, M Wang, G Warren, F Wesselmann, B Wojtsekhowski, S A Wood, C Xu, L Yuan, X Zheng, H Zhu
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  ABSTRACT: A large data set of charged-pion (pi+/-) electroproduction from both hydrogen and deuterium targets has been obtained spanning the low-energy residual-mass region. These data conclusively show the onset of the quark-hadron duality phenomenon, as predicted for high-energy hadron electroproduction. We construct several ratios from these data to exhibit the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark-->pion production mechanisms.
  Physical Review Letters 01/2007; 98(2):022001. · 7.37 Impact Factor
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  Available from: Donal Bruce Day

  Article: Nuclear transparency from quasielastic 12C(e,e'p)

  D. Rohe, O. Benhar, C. S. Armstrong, R. Asaturyan, O.K. Baker, S. Bueltmann, C. Carasco, D. Day, R. Ent, H. C. Fenker, [......], S Stepanyan, L Tang, F. Tiefenbacher, W. F. Vulcan, G. Warren, S. A. Wood, L Yuan, M. Zeier, H Zhu, B. Zihlmann
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  ABSTRACT: We studied the reaction 12C(e,e'p) in quasielastic kinematics at momentum transfers between 0.6 and 1.8 (GeV/c)^2 covering the single-particle region. From this the nuclear transparency factors are extracted using two methods. The results are compared to theoretical predictions obtained using a generalization of Glauber theory described in this paper. Furthermore, the momentum distribution in the region of the 1s-state up to momenta of 300 MeV/c is obtained from the data and compared to the Correlated Basis Function theory and the Independent-Particle Shell model.
  07/2005;
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  Available from: John Robert Arrington

  Article: Measurements of R = σ L /σ T and the Separated Longitudinal and Transverse Structure Functions in the Nucleon Resonance Region

  Y Liang, M E Christy, A Ahmidouch, C S Armstrong, J Arrington, R Asaturyan, S Avery, O K Baker, D.H. Beck, H.P. Blok, [......], R. Tieulent, V. Tvaskis, A. Uzzle, W.F. Vulcan, S.A. Wood, F. Xiong, L. Yuan, M. Zeier, B. Zihlmann, V. Ziskin
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  ABSTRACT: We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from in-clusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 <Q 2 < 5.5 GeV 2 . The data have been used to accurately perform over 170 Rosenbluth-type longitudinal / transverse separa-tions. The precision R = σL/σT data are presented here, along with the first separate values of the inelastic structure functions F1 and FL in this regime. The resonance longitudi-nal component is found to be significant. With the new data, quark-hadron duality is observed above Q 2 = 1 GeV 2 in the separated structure functions independently.
  nucl-ex/0410027. 11/2004;
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  Available from: Donal Bruce Day

  Article: Correlated strength in the nuclear spectral function.

  D Rohe, C S Armstrong, R Asaturyan, O K Baker, S Bueltmann, C Carasco, D Day, R Ent, H C Fenker, K Garrow, [......], S Stepanyan, L Tang, F Tiefenbacher, W F Vulcan, G Warren, S A Wood, L Yuan, M Zeier, H Zhu, B Zihlmann
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  ABSTRACT: We have carried out an (e,e'p) experiment at high momentum transfer and in parallel kinematics to measure the strength of the nuclear spectral function S(k,E) at high nucleon momenta k and large removal energies E. This strength is related to the presence of short-range and tensor correlations, and was known hitherto only indirectly and with considerable uncertainty from the lack of strength in the independent-particle region. This experiment locates by direct measurement the correlated strength predicted by theory.
  Physical Review Letters 11/2004; 93(18):182501. · 7.37 Impact Factor
• Article: Measurement of the high energy two-body deuteron photodisintegration differential cross section.

  E C Schulte, A Ahmidouch, C S Armstrong, J Arrington, R Asaturyan, S Avery, O K Baker, D H Beck, H P Blok, C W Bochna, [......], L Tang, R Tieulent, A Uzzle, W F Vulcan, S A Wood, F Xiong, L Yuan, M Zeier, B Zihlmann, V Ziskin
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  ABSTRACT: The first measurements of the d(gamma,p)n differential cross section at forward angles and photon energies above 4 GeV were performed at the Thomas Jefferson National Accelerator Facility (JLab). The results indicate evidence of an angular dependent scaling threshold. Results at straight theta(cm) = 37 degrees are consistent with the constituent counting rules for E(gamma) greater, similar 4 GeV, while those at 70 degrees are consistent with the constituent counting rules for E(gamma) greater, similar 1.5 GeV.
  Physical Review Letters 10/2001; 87(10):102302. · 7.37 Impact Factor
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  Available from: John Robert Arrington

  Article: x- and xi-scaling of the Nuclear Structure Function at Large x

  J. Arrington, C. S. Armstrong, T. Averett, O.K. Baker, L. de Bever, C. W. Bochna, W. Boeglin, B. Bray, R. D. Carlini, G. Collins, [......], T. Petitjean, O. Rondon, I. Sick, C Smith, B. Terburg, W. F. Vulcan, S. A. Wood, C Yan, J Zhao, B. Zihlmann
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  ABSTRACT: Inclusive electron scattering data are presented for ^2H and Fe targets at an incident electron energy of 4.045 GeV for a range of momentum transfers from Q^2 = 1 to 7 (GeV/c)^2. Data were taken at Jefferson Laboratory for low values of energy loss, corresponding to values of Bjorken x greater than or near 1. The structure functions do not show scaling in x in this range, where inelastic scattering is not expected to dominate the cross section. The data do show scaling, however, in the Nachtmann variable \xi. This scaling may be the result of Bloom Gilman duality in the nucleon structure function combined with the Fermi motion of the nucleons in the nucleus. The resulting extension of scaling to larger values of \xi opens up the possibility of accessing nuclear structure functions in the high-x region at lower values of Q^2 than previously believed. Comment: RevTeX, 5 pages with 4 postscript figures, submitted to PRC
  02/2001;
• Article: Coherent pi-0 photoproduction on the deuteron up to 4-GeV

  D. G. Meekins, D. J. Abbott, A. Ahmidouch, C. S. Armstrong, J. Arrington, K. A. Assamagan, O. K. Baker, S.P. Barrow, D.P. Beatty, D.H.Beck, [......], R. Suleiman, L. Tang, B.P. Terburg, D.van Westrum, W.F. Vulcan, S.E. Williamson, M.T. Witkowski, S.A. Wood, C. Yan, B. Zeidman
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  ABSTRACT: The differential cross section for 2H(γ,d)π0 has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions.
  Physical Review C. 09/1999; 60(5):052201.