Sample records for type-of-sale clas sification

  1. Hyperon Production with CLAS and CLAS12

    SciTech Connect (OSTI)

    Eugene Pasyuk

    2012-12-01T23:59:59.000Z

    Hadron spectroscopy and baryon spectroscopy in particular represents a large part of the experimental program with CLAS at Jefferson Lab. Within this program a substantial amount of data on hyperon production and properties has been accumulated. This includes photo- and electro-production of {Lambda} and {Sigma} hyperons and their excited states and also {Xi} hyperons. Some of the highlights of this program will be presented together with plans to extend this program with CLAS12 after CEBAF upgrade to 12 GeV.

  2. Spin physics with CLAS and CLAS12

    SciTech Connect (OSTI)

    Angela Biselli

    2011-10-01T23:59:59.000Z

    An extensive experimental program to measure the spin structure of the nucleon has been conducted in Hall B at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) in the last decade. Using a longitudinally polarized beam scattering off longitudinally polarized NH3 and ND3 targets, inclusive Deep Inelastic Scattering (DIS), Semi-Inclusive DIS (SIDIS) and DVCS experiments were carried out that make a significant contributions to the existing data. The inclusive double spin asymmetry A|| was measured over a large range in Q2 and W, providing data of impressively high precision that give a better understanding of the structure of the nucleon in the DIS and the valence quarks regions. Using parameterizations A2 and F1 from world data, the virtual photon asymmetry A1 and the structure function g1 were extracted in a Q2 range from 0.05 to 5 GeV2 and a W range from 1.08 to 3.0 GeV. As a result of the extended kinematical range, first moments of structure functions were measured over a large range in Q2 and duality was tested. Furthermore, newly proposed experiments, using an upgraded accelerator at Jefferson Laboratory and an improved CLAS detector (CLAS12), are expected to increase the statistical precision of the current measurements and extend them to kinematic regions presently not accessible, such as high x. This will improve significantly our knowledge of the structure of the nucleon, including parton distribution functions, duality and higher twists contributions.

  3. Studies of TMDs with CLAS

    SciTech Connect (OSTI)

    Aghasyan, Mher M. [Lab. Naz. Frascati, Frascati, Italy; Avakian, Harut A. [JLAB

    2013-07-01T23:59:59.000Z

    Studies of single and double-spin asymmetries in pion electro-production in semi-inclusive deep-inelastic scattering of 5.8 GeV polarized electrons from unpolarized and longitudinally polarized targets at the Thomas Jefferson National Accelerator Facility using CLAS discussed. We present a Bessel-weighting strategy to extract transverse-momentum-dependent parton distribution functions.

  4. The CLAS Forward Electromagnetic Calorimeter

    SciTech Connect (OSTI)

    M. Amarian; Geram Asryan; Kevin Beard; Will Brooks; Volker Burkert; Tom Carstens; Alan Coleman; Raphael Demirchyan; Yuri Efremenko; Hovanes Egiyan; Kim Egiyan; Herb Funsten; Vladimir Gavrilov; Kevin L. Giovanetti; R.M. Marshall; Berhard Mecking; R.C. Minehart; H. Mkrtchan; Mavrik Ohandjanyan; Youri Sharabian; L.C. Smith; Stepan Stepanyan; W.A. Stephens; T.Y. Tung; Carl Zorn

    2001-05-01T23:59:59.000Z

    The CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab utilizes six iron-free superconducting coils to provide an approximately toroidal magnetic field. The six sectors are instrumented individually to form six independent spectrometers. The forward region (8deg < (theta) < 45deg) of each sector is equipped with a lead-scintillator electromagnetic sampling calorimeter (EC), 16 radiation lengths thick, using a novel triangular geometry with stereo readout. With its good energy and position resolution, the EC is used to provide the primary electron trigger for CLAS. It is also used to reject pions, reconstruct pi-0 and eta decays and detect neutrons, This paper treats the design, construction and performance of the calorimeter.

  5. Cascade photo production at CLAS

    SciTech Connect (OSTI)

    Goetz, John [Ohio University, JLAB; Hicks, Kenneth H. [Ohio University, JLAB

    2014-09-01T23:59:59.000Z

    The famous discovery of the Omega ? in 1964 put the quark model on firm ground and since then a lot of effort has been spent on mapping out the baryonic and mesonic states. Over the following decades, many excited baryons with light quarks (up, down and strange) have been measured, but by most predictions, only a small percentage of those expected have been found. In this talk, I will discuss a newly developing technique using an (unflavored) photon beam to excite protons to doubly-strange "Cascade" (Xi) states. Advantages of such an experiment and associated difficulties will be presented, along with recent results from the CLAS detector at Jefferson Lab in Virginia.

  6. Meson Photoproduction Experiments with CLAS

    SciTech Connect (OSTI)

    Eugene Pasyuk

    2012-12-01T23:59:59.000Z

    A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to light baryon spectroscopy. Meson photoprodcution experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams and frozen spin polarized targets provide unique conditions for this type of experiments. This combination of experimental tools gives a remarkable opportunity to measure double polarization observables for different pseudo-scalar meson photoproduction processes. For the first time, a complete or nearly complete measurement became possible and will facilitate model independent extraction of the reaction amplitude. An overview of the experimental program and its current status together with recent results on double polarization measurements in ?{sup +} photoproduction are presented.

  7. CLAS-NOTE 2011-006 The CLAS Shifts Schedule and Productivity Management Tools

    E-Print Network [OSTI]

    Glasgow, University of

    School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom (Dated: April 24. Experimental Program 6 IV. Service Work 6 A. Submission 6 B. Reviews (Audits) 7 C. Summary Tables 8 D. CLAS12-of-its-kind among nuclear and high-energy physics collaborations and was created specifically for the CLAS

  8. Magnetic System for the CLAS12 Proposal

    SciTech Connect (OSTI)

    Statera, Marco [INFN, Ferrara (Italy); Contalbrigo, Marco M. [INFN, Ferrara (Italy); Pappalardo, Luciano Libero [INFN, Ferrara (Italy); Barion, Luca [INFN, Ferrara (Italy); Bertelli, S. [INFN, Ferrara (Italy); Ciullo, Giuseppe [INFN, Ferrara (Italy); Lenisa, Paolo [INFN, Ferrara (Italy)

    2013-06-01T23:59:59.000Z

    The conceptual design of a magnetic system for an experiment to measure the transverse spin effects in semi-inclusive Deep Inelastic Scattering (SIDIS) at 11 GeV with a transversely polarized target using the CLAS12 detector at Jefferson Lab is presented. A proposal has been submitted to study spin azimuthal asymmetries in SIDIS using an 11-GeV polarized electron beam from the upgraded CEBAF facility and the CLAS12 detector equipped with a transversely polarized target. The main focus of the experiment will be the measurement of transverse target single and double spin asymmetries in the reaction ep{up_arrow} -> ehX, where e is an electron, p{up_arrow} is transversely polarized proton, h is a meson (e.g., a pion or a kaon) and X is the undetected final state. The details of the conceptual design of the shielding magnetic system and transverse dipole are reported.

  9. Search for New and Unusual Stangonia using CLAS

    SciTech Connect (OSTI)

    Saini, Mukesh Satyapraka [Florida State U.

    2013-03-01T23:59:59.000Z

    We perform a survey of the proton, K^+, K^- -3 charged track data, taken by the CLAS detector for the HyCLAS experiment during the g12 run-period at Jefferson Lab. We aim to study the strong decay amplitudes, partial widths and production channels of strangeonia from the CLAS g12 dataset. HyCLAS was motivated by the experimental results for gluonic hybrid meson candidates, theoretical Lattice QCD, and Flux-tube Model calculations and predictions. The experiment was designed and conducted to search and observe new forms of hadronic matter through photoproduction.

  10. Status of Meson Photoproduction Experiments with CLAS

    SciTech Connect (OSTI)

    Pasyuk, Eugene A.

    2014-01-01T23:59:59.000Z

    A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Meson photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams in combination with longitudinally and transversely polarized frozen spin targets provide unique conditions for this type of experiments. For the first time, a complete or nearly complete measurement became possible and will allow model independent extraction of the reaction amplitude. The measurements were complete with both proton and deuteron targets. An overview of the collected experimental data will be presented.

  11. Di-hadron SIDIS measurements at CLAS

    SciTech Connect (OSTI)

    Pisano, Silvia [Lab. Naz. Frascati, Frascati, Italy

    2014-06-01T23:59:59.000Z

    Semi-inclusive deep-inelastic scattering (SIDIS) is an essential tool to probe nucleon internal structure. Through single hadron SIDIS processes, indeed, it is possible to access the TMDs, containing information on both the longitudinal and transverse motion of the partons. In recent years, moreover, an increasing attention has been devoted to dihadron SIDIS. It constitutes the golden channel to access the higher-twist collinear Parton Distribution Functions e(x) and h{sub L}(x), so far only marginally known, whose extraction will complete the collinear description of the nucleon at the twist-3 level. The CLAS detector in the Hall-B at JLab, thanks to its large acceptance, is particularly suited for such measurements. Analyses aiming at the extraction of dihadron SIDIS Beam and Target-Spin Asymmetries are presently in progress. In these proceedings, preliminary results for the Beam-Spin Asymmetry are reported, together with a summary of the dihadron SIDIS experimental program at JLab.

  12. Overview of the recent results from CLAS

    SciTech Connect (OSTI)

    Marco Mirazita

    2012-03-01T23:59:59.000Z

    An overview of the recent results obtained at the Thomas Jefferson Laboratory on the study of the nucleon internal structure is presented, with main focus on the CLAS measurements of the Transverse Momentum Dependent partonic functions. The JLab with its CEBAF accelerator and the three experimentals halls is a Laboratory dedicated to the study of the hadronic physics with electromagnetic probes in a large variety of aspects. The physics program extends from typical nuclear effects like long range correlations in nuclei to the study of the short distance vacuum structure in parity violating experiments. In recent years, a big part of the physics program was devoted to the study of the Transverse Momentum Dependent distribution functions, new functions introduced to describe the internal structure of the nucleon. Studies of TMDs at JLab and in other laboratories have shown sizeable effects due to transverse motion of the quarks inside the nucleon, but also have open questions. These questions need to be addressed in a new generation of experiments, poviding higher precisions experimental data, and with new analysis techniques, necessary to unfold fundamental properties from the measured obsevables.

  13. CLAS C308 Roman Law C. J. Bannon SYLLABUS Fall 2012

    E-Print Network [OSTI]

    Indiana University

    CLAS C308 Roman Law C. J. Bannon SYLLABUS Fall 2012 Professor Cynthia J. Bannon Office: Ballantine% Research Paper 20% #12;CLAS C308 Roman Law C. J. Bannon SYLLABUS Fall 2012 Course Policies and Expectations

  14. Time of Flight Software for the CLAS12 Particle Detector

    E-Print Network [OSTI]

    Gilfoyle, Jerry

    , Virginia is the Continuous Electron Beam Accelerator Facility (CEBAF), which supplies beams of electrons CEBAF Continuous Electron Beam Accelerator Facility CLARA CLAS12 Analysis and Reconstruction Framework at the Thomas Jefferson National Accelerator Facility (also Jefferson Laboratory, or Jlab) in Newport News

  15. A ring imaging Cherenkov detector for CLAS12

    SciTech Connect (OSTI)

    Montgomery, Rachel A. [Glasgow University

    2013-12-01T23:59:59.000Z

    The energy increase of Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) to 12 GeV promises to greatly extend the physics reach of its experiments. This will include an upgrade of the CEBAF Large Acceptance Spectrometer (CLAS) to CLAS12, offering unique possibilities to study internal nucleon dynamics. For this excellent hadron identification over the full kinematical range of 3–8 GeV/c is essential. This will be achieved by the installation of a Ring Imaging CHerenkov (RICH) detector. A novel hybrid imaging design incorporating mirrors, aerogel radiators and Hamamatsu H8500 multianode photomultiplier tubes is proposed. Depending on the incident particle track angle, Cherenkov light will either be imaged directly or after two reflections and passes through the aerogel. The detector design is described, along with preliminary results on individual detector components tests and from recent testbeam studies.

  16. Analysis of CLAS data on double charge pion electroproduction

    E-Print Network [OSTI]

    Viktor Mokeev; Volker Burkert; Latifa Elouadrhiri; Gleb Fedotov; Evgeny Golovach; Eugeny Isupov; Boris Ishkhanov; Nikolay Shvedunov

    2007-10-31T23:59:59.000Z

    Recent developments in phenomenological analysis of the CLAS data on 2$\\pi$ electroproduction are presented. The contributions from isobar channels and $P_{11}(1440)$, $D_{13}(1520)$ electrocouplings at $Q^{2}$ from 0.25 to 0.6 GeV$^2$ were determined from the analysis of comprehensive data on differential and fully integrated 2$\\pi$ cross sections. Experiment Numbers: E94-005 Group: Hall B

  17. Neutron Structure — New Results with CLAS at Jefferson Lab

    SciTech Connect (OSTI)

    Sebastian Kuhn

    2006-11-01T23:59:59.000Z

    New measurements using the 6 GeV continuous electron beam and the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab have collected information on the form factors and the unpolarized structure functions of the neutron, with minimal uncertainty from nuclear binding effects. One experiment has also tried to measure these binding effects more directly, using the method of ''spectator tagging''. These experiments are forerunners for an extensive program with the energy-upgraded 12 GeV accelerator at Jefferson Lab.

  18. Generalized Parton Distributions from Deep Virtual Compton Scattering at CLAS

    E-Print Network [OSTI]

    M. Guidal

    2010-03-01T23:59:59.000Z

    We have analyzed the beam spin asymmetry and the longitudinally polarized target spin asymmetry of the Deep Virtual Compton Scattering process, recently measured by the Jefferson Lab CLAS collaboration. Our aim is to extract information about the Generalized Parton Distributions of the proton. By fitting these data, in a largely model-independent procedure, we are able to extract numerical values for the two Compton Form Factors $H_{Im}$ and $\\tilde{H}_{Im}$ with uncertainties, in average, of the order of 30%.

  19. Light Baryon Spectroscopy using the CLAS Spectrometer at Jefferson Laboratory

    SciTech Connect (OSTI)

    Volker Crede

    2011-12-01T23:59:59.000Z

    Baryons are complex systems of confined quarks and gluons and exhibit the characteristic spectra of excited states. The systematics of the baryon excitation spectrum is important to our understanding of the effective degrees of freedom underlying nucleon matter. High-energy electrons and photons are a remarkably clean probe of hadronic matter, providing a microscope for examining the nucleon and the strong nuclear force. Current experimental efforts with the CLAS spectrometer at Jefferson Laboratory utilize highly-polarized frozen-spin targets in combination with polarized photon beams. The status of the recent double-polarization experiments and some preliminary results are discussed in this contribution.

  20. Nucleon Resonance Electrocouplings from the CLAS Meson Electroproduction Data.

    SciTech Connect (OSTI)

    Inna Aznauryan, Volker Burkert, Viktor Mokeev

    2012-04-01T23:59:59.000Z

    Transition helicity amplitudes {gamma}{sub {nu}}NN* (electrocouplings) were determined for prominent excited proton states with masses less than 1.8 GeV in independent analyses of major meson electroproduction channels: {pi}{sup +}n, {pi}{sup 0}p and {pi}{sup +}{pi}{sup -}p. Consistent results on resonance electrocouplings obtained from analyses of these exclusive reactions with very different non-resonant contributions demonstrated reliable extraction of these fundamental quantities for states that have significant decays for either N{pi} or N{pi}{pi} channels. Preliminary results on electrocouplings of N* states with masses above 1.6 GeV have become available from the CLAS data on {pi}{sup +}{pi}{sup -}p electroproduction off protons for the first time. Comparison with quark models and coupled channel approaches strongly suggest that N* structure is determined by contributions from an internal core of three constituent quarks and an external meson-baryon cloud at the distance scales covered in measurements with the CLAS detector.

  1. Deep exclusive $?^+$ electroproduction off the proton at CLAS

    E-Print Network [OSTI]

    K. Park; M. Guidal; R. W. Gothe; J. M. Laget; M. Garçon; K. P. Adhikari; M. Aghasyan; M. J. Amaryan; M. Anghinolfi; H. Avakian; H. Baghdasaryan; J. Ball; N. A. Baltzell; M. Battaglieri; I. Bedlinsky; R. P. Bennett; A. S. Biselli; C. Bookwalter; S. Boiarinov; W. J. Briscoe; W. K. Brooks; V. D. Burkert; D. S. Carman; A. Celentano; S. Chandavar; G. Charles; M. Contalbrigo; V. Crede; A. D'Angelo; A. Daniel; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; G. E. Dodge; D. Doughty; R. Dupre; H. Egiyan; A. El Alaoui; L. El Fassi; A. Fradi; P. Eugenio; G. Fedotov; S. Fegan; J. A. Fleming; T. A. Forest; N. Gevorgyan; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; W. Gohn; E. Golovatch; L. Graham; K. A. Griffioen; B. Guegan; L. Guo; K. Hafidi; H. Hakobyan; C. Hanretty; D. Heddle; K. Hicks; D. Ho; M. Holtrop; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; D. Jenkins; H. S. Jo; D. Keller; M. Khandaker; P. Khetarpal; A. Kim; W. Kim; F. J. Klein; S. Koirala; A. Kubarovsky; V. Kubarovsky; S. E. Kuhn; S. V. Kuleshov; K. Livingston; H. Y. Lu; I. J. D. MacGregor; Y. Mao; N. Markov; D. Martinez; M. Mayer; B. McKinnon; C. A. Meyer; T. Mineeva; M. Mirazita; V. Mokeev; H. Moutarde; E. Munevar; C. Munoz Camacho; P. Nadel-Turonski; C. S. Nepali; S. Niccolai; G. Niculescu; I. Niculescu; M. Osipenko; A. I. Ostrovidov; L. L. Pappalardo; R. Paremuzyan; S. Park; E. Pasyuk; S. Anefalos Pereira; E. Phelps; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; S. Procureur; D. Protopopescu; A. J. R. Puckett; B. A. Raue; G. Ricco; D. Rimal; M. Ripani; G. Rosner; P. Rossi; F. Sabatie; M. S. Saini; C. Salgado; D. Schott; R. A. Schumacher; E. Seder; H. Seraydaryan; Y. G. Sharabian; E. S. Smith; G. D. Smith; D. I. Sober; D. Sokhan; S. S. Stepanyan; P. Stoler; I. I. Strakovsky; S. Strauch; M. Taiuti; W. Tang; C. E. Taylor; Ye Tian; S. Tkachenko; A. Trivedi; M. Ungaro; B . Vernarsky; H. Voskanyan; E. Voutier; N. K. Walford; D. P. Watts; L. B. Weinstein; D. P. Weygand; M. H. Wood; N. Zachariou; J. Zhang; Z. W. Zhao; I. Zonta

    2013-01-11T23:59:59.000Z

    The exclusive electroproduction of $\\pi^+$ above the resonance region was studied using the $\\rm{CEBAF}$ Large Acceptance Spectrometer ($\\rm{CLAS}$) at Jefferson Laboratory by scattering a 6 GeV continuous electron beam off a hydrogen target. The large acceptance and good resolution of $\\rm{CLAS}$, together with the high luminosity, allowed us to measure the cross section for the $\\gamma^* p \\to n \\pi^+$ process in 140 ($Q^2$, $x_B$, $t$) bins: $0.16

  2. Status of Hall B superconducting magnets for the CLAS12 detector at JLab

    SciTech Connect (OSTI)

    Quettier, L; Kashy, D; Elouadrhiri, L; Salpietro, E; Schneider, W; Small, R; Leung, E; Juang, T; McMullin, J; Taylor, C; Xu, L; Wagner, B; Wang, B; Wang, M

    2011-12-01T23:59:59.000Z

    Hadron physics has been an essential part of the physics program with the CLAS detector in experimental hall B at Thomas Jefferson National Accelerator Facility (Jefferson Lab). With the 12 GeV upgrade of the CEBAF machine, hadron physics in Hall B will be extended to a new domain of higher mass resonances and the range of higher transferred momentum using up to 11 GeV electron beams and the upgraded CLAS12 detector. In this paper, status of the hall B superconducting magnets for the CLAS12 detector is presented.

  3. eA Pion Production at CLAS Aimed at Neutrinos

    SciTech Connect (OSTI)

    Steven Manly

    2011-11-01T23:59:59.000Z

    Preliminary results on semi-inclusive charged pion production in eA collisions at E{sub beam} = 5 GeV/c{sup 2} are presented. The data were collected using the CLAS detector, which is a multipurpose, large acceptance, magnetic spectrometer located in Hall B at the Thomas Jefferson National Accelerator Facility. Distributions in W, Q{sup 2}, p{sub {pi}}, and {theta}{sub {pi}} are shown for data produced using deuterium and carbon targets. Preliminary comparisons with data simulated using the GENIE generator are made. The motivation for this work is to provide distributions useful for tuning the hadronic production models used in extracting results from current and next-generation neutrino oscillation experiments.

  4. CLAS data and progress in the investigation of electro-excitation of nucleon resonances

    SciTech Connect (OSTI)

    M. Ungaro

    2011-05-01T23:59:59.000Z

    We present an overview of selected CLAS nucleon excitations results: electro-production of single pion from the Delta(1232), Roper, D_13(1520) resonances and electro-production of double pion Npi^+pi^- . These and other CLAS measurements, coupled with recent theoretical developments, will allow non-perturbative approaches to shed lights on the role of quarks and gluons in nuclei and address issues such as confinement and the non-zero quark mass in the chiral limit.

  5. Deeply virtual Compton Scattering cross section measured with CLAS

    SciTech Connect (OSTI)

    Guegan, Baptistse [Institut de Physique Nucleaire, Orsay

    2014-09-01T23:59:59.000Z

    The Generalized Parton Distributions (GPDs) provide a new description of nucleon structure in terms of its elementary constituents, the quarks and the gluons. Including and extending the information provided by the form factors and the parton distribution functions, they describe the correlation between the transverse position and the longitudinal momentum fraction of the partons in the nucleon. Deeply Virtual Compton Scattering (DVCS), the electroproduction of a real photon on a single quark in the nucleon eN --> e'N'g, is the exclusive process most directly interpretable in terms of GPDs. A dedicated experiment to study DVCS with the CLAS detector at Jefferson Lab has been carried out using a 5.9-GeV polarized electron beam and an unpolarized hydrogen target, allowing us to collect DVCS events in the widest kinematic range ever explored in the valence region : 1.0 < Q2 < 4.6 GeV2, 0.1 < xB < 0.58 and 0.09 < -t < 2.0 GeV2. In this paper, we show preliminary results of unpolarized cross sections and of polarized cross section differences for the DVCS channel.

  6. Hall B superconducting magnets for the CLAS12 detector at JLAB

    SciTech Connect (OSTI)

    L. Quettier, V. Burkert, L. Elouadrhiri, D. Kashy, E. Leung, W. Schneider

    2011-02-01T23:59:59.000Z

    Hadron physics has been an essential part of the physics program with the CLAS detector in experimental hall B at Thomas Jefferson National Accelerator Facility (Jefferson Lab). With the 12 GeV upgrade of the CEBAF machine, hadron physics in Hall B will be extended to a new domain of higher mass resonances and the range of higher transferred momentum using up to 11 GeV electron beams and the upgraded CLAS12 detector. In this paper, status of the hall B superconducting magnets for the 12 GeV upgrade is presented.

  7. Phenomenological analysis of the CLAS data on double charged pion photo and electro- production

    SciTech Connect (OSTI)

    Viktor Mokeev; Volker Burkert; Latifa Elouadrhiri; A.A. Boluchevsky; Gleb Fedotov; Eugeny Isupov; Boris Ishkhanov; Nikolay Shvedunov

    2005-10-01T23:59:59.000Z

    First comprehensive data on the evolution of nucleon resonance photocouplings with photon virtuality Q{sup 2} are presented for excited proton states in the mass range from 1.4 to 2.0 GeV. N* photocouplings were determined in phenomenological analysis of CLAS data on 2 pi photo and electroproduction within the framework of the JLAB-MSU phenomenological model.

  8. Beam spin asymmetries in deeply virtual Compton scattering (DVCS) with CLAS at 4.8 GeV

    E-Print Network [OSTI]

    Prok, Yelena

    We report measurements of the beam spin asymmetry in deeply virtual Compton scattering (DVCS) at an electron beam energy of 4.8 GeV using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The DVCS ...

  9. Improvement of the technique of identification of electrons and positrons with use of electromagnetic calorimeter of the CLAS detector

    SciTech Connect (OSTI)

    Gevorgyan, N. E.; Dashyan, N. B.; Paremuzyan, R. G.; Stepanyan, S. G.

    2010-01-01T23:59:59.000Z

    We study the dependence of the sensitivity of response of the electromagnetic calorimeter of CLAS plant on the momenta of electrons and positrons. We made calculation of this dependence and elaborated a method for its employment in identification of e- and e+. We have shown that the new method of selection of e- and e+ improves the quality of identification by about 10%. We used the experimental data obtained with the plant CLAS of linear accelerator at Jefferson laboratory (USA).

  10. Measurements of transverse momentum in semi-inclusive deep-inelastic scattering at CLAS

    SciTech Connect (OSTI)

    K.A. Griffioen

    2012-12-01T23:59:59.000Z

    With mounting experimental evidence that only a small fraction of the proton's spin comes from the spins of its quarks and gluons, the quest for orbital angular momentum has begun. The parton distributions relevant to this depend on transverse quark momenta. Recent CLAS semi-inclusive deep-inelastic scattering measurements probe these new transverse-momentum-dependent parton distributions using longitudinally polarized beams and targets and detecting {pi}{sup +},{pi}{sup -} and {pi}{sup 0} in the final state.

  11. A new measurement of Beam Asymmetry in Pion Photoproduction from the Neutron using CLAS

    SciTech Connect (OSTI)

    D. Sokhan, D. Watts, D. Branford, F. Klein

    2010-08-01T23:59:59.000Z

    We present a preliminary analysis of the photon beam asymmetry observable (Sigma) from the photoproduction reaction channel gamma+ n -> p + pi-. This new data was obtained using the near-4pi CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Laboratory, USA, employing a linearly polarised photon beam with an energy range 1.1 - 2.3 GeV. The measurement will provide new data to address the poorly established neutron excitation spectrum and will greatly expand the sparse world data-set both in energy and angle.

  12. Studies of 3D structure of the nucleon with CLAS at Jlab

    SciTech Connect (OSTI)

    Mher Aghasyan

    2011-12-01T23:59:59.000Z

    Studies of single-spin asymmetries in pions electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized and polarized targets, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility, are presented. A substantial sin phih amplitude has been measured in the the cross section as a function of the azimuthal angle phih of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum has been extracted with significantly higher precision than previous data and is compared to model calculations.

  13. Studies of 3D structure of the nucleon with CLAS at JLab

    SciTech Connect (OSTI)

    Aghasyan, Mher [INFN, Laboratori Nazionali di Frascati, 00044 Frascati (Italy); Collaboration: CLAS Collaboration

    2011-12-14T23:59:59.000Z

    Studies of single-spin asymmetries in pions electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized and polarized targets, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility, are presented. A substantial sin {phi}{sub h} amplitude has been measured in the the cross section as a function of the azimuthal angle {phi}{sub h} of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum has been extracted with significantly higher precision than previous data and is compared to model calculations.

  14. Deep exclusive {pi}{sup +} electroproduction off the proton at CLAS

    SciTech Connect (OSTI)

    Park, Kijun; Gothe, Ralf; Guidal, Michel; Laget, Jean; Adhikari, K P; Bennet, R P; Biselli, A S; Chandavar, S; MacGregor, I. J. D; Munoz Camacho, C; Anefalos-Pereira, S; Rimal, D; Tang, W

    2013-01-01T23:59:59.000Z

    The exclusive electroproduction of {pi}{sup +} above the resonance region was studied using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Laboratory by scattering a 6 GeV continuous electron beam off a hydrogen target. The large acceptance and good resolution of CLAS, together with the high luminosity, allowed us to measure the cross section for the {gamma}* p {yields} n {pi}{sup +} process in 140 (Q{sup 2}, x{sub B}, t) bins: 0.16

  15. The CLAS Start Counter S. Taylor a , S. Ahmad d , J. Distelbrink c , G. S. Mutchler a ,

    E-Print Network [OSTI]

    Thomas Jefferson National Accelerator Facility

    Overview of CLAS The Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Je#erson National Accelerator Facility currently delivers CW electron beam up to #6 GeV in energy. The machine can deliver B at the Thomas Je#erson National Accelerator Facility. The Start Counter is constructed of three 3

  16. Measurement of the nuclear multiplicity ratio or image hadronization at CLAS

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Daniel, A; Brooks, W K; Hakobyan, H; Adhikari, K P; Adikaram, D; Aghasyan, M; Amarian, M; Anghinolfi, M; Avakian, H; Baghdasryan, H; et al

    2011-11-30T23:59:59.000Z

    The influence of cold nuclear matter on lepto-production of hadrons in semi-inclusive deep inelastic scattering is measured using the CLAS detector in Hall B at Jefferson Lab and a 5.014 GeV electron beam. We report the View the MathML source multiplicity ratios for targets of C, Fe, and Pb relative to deuterium as a function of the fractional virtual photon energy z transferred to the View the MathML source and the transverse momentum squared View the MathML source of the View the MathML source. We find that the multiplicity ratios for View the MathML source are reduced in the nuclearmore »medium at high z and low View the MathML source, with a trend for the View the MathML source transverse momentum to be broadened in the nucleus for large View the MathML source.« less

  17. Coherent photoproduction of {pi}{sup +} from {sup 3}He with CLAS at Jefferson Lab

    SciTech Connect (OSTI)

    Nasseripour, Rakhsha; Berman, Barry [George Washington University, Washington, DC 20052 (United States)

    2011-10-24T23:59:59.000Z

    We have measured the differential cross section for the {gamma}{sup 3}He{yields}{pi}{sup +}t reaction. This reaction was studied using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.5 to 1.55 GeV were incident on a cryogenic liquid {sup 3}He target. The differential cross sections for the {gamma}{sup 3}He{yields}{pi}{sup +}t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, showing that additional components must be added to the model.

  18. Coherent photoproduction of pi+ from He-3 with CLAS at Jefferson Laboratory

    SciTech Connect (OSTI)

    Rakhsha Nasseripour, Barry Berman

    2011-09-01T23:59:59.000Z

    We have measured the differential cross section for the {gamma}{sup 3}He {yields} t{pi}{sup +} reaction. This reaction was studied using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.5 to 1.55 GeV were incident on a cryogenic liquid {sup 3}He target. The differential cross sections for the {gamma}{sup 3}He {yields} i{pi}{sup +}t reaction were measured as a function of photon-beam energy and pion-scattering angle Theoretical predictions to date cannot explain the large cross sections except at backward angles, showing that additional components must be added to the model.

  19. Exclusive pi^0 electroproduction at W > 2 GeV with CLAS

    SciTech Connect (OSTI)

    Bedlinskiy, I.; Kubarovsky, V.; Niccolai, S.; Stoler, P.; Adhikari, K.P.; Anderson, M.D.; Pereira, S. Anefalos; Avakian, H.; Ball, J.; Baltzell, N.A.; Battaglieri, M.; Batourine, V.; Biselli, A.S.; Boiarinov, S.; Bono, J.; Briscoe, W.J.; Brooks, W.K.; Burkert, V.D.; Carman, D.S.; Celentano, A.; Chandavar, S.; Colaneri, L.; Cole, P.L.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fleming, J.A.; Forest, T.A.; Garillon, B.; Garcon, M.; Gavalian, G.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G.P.; Giovanetti, K.L.; Girod, F.X.; Golovatch, E.; Gothe, R.W.; Griffioen, K.A.; Guegan, B.; Guo, L.; Hafidi, K.; Hakobyan, H.; Harrison, N.; Hattawy, M.; Hicks, K.; Holtrop, M.; Ireland, D.G.; Ishkhanov, B.S.; Isupov, E.L.; Jenkins, D.; Jo, H.S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F.J.; Koirala, S.; Kuhn, S.E.; Kuleshov, S.V.; Lenisa, P.; Levine, W.I.; Livingston, K.; Lu, H.Y.; MacGregor, I.J.D.; Markov, N.; Mayer, M.; McKinnon, B.; Mirazita, M.; Mokeev, V.; Montgomery, R.A.; Moody, C.I.; Moutarde, H.; Movsisyan, A; Munoz Camacho, C.; Nadel-Turonski, P.; Niculescu, I.; Osipenko, M.; Ostrovidov, A.I.; Pappalardo, L.L.; Park, K.; Park, S.; Pasyuk, E.; Phelps, E.; Phelps, W.; Phillips, J.J.; Pisano, S.; Pogorelko, O.; Price, J.W.; Prok, Y.; Protopopescu, D.; Procureur, S.; Puckett, A.J.R.; Raue, B.A.; Ripani, M.; Ritchie, B.G.; Rizzo, A.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R.A.; Seder, E.; Senderovich, I.; Sharabian, Y.G.; Simonyan, A.; Smith, G.D.; Sober, D.I.; Sokhan, D.; Stepanyan, S.S.; Strauch, S.; Sytnik, V.; Tang, W.; Tian, Ye; Ungaro, M.; Vlassov, A.V.; Voskanyan, H.; Voutier, E.; Walford, N.K.; Watts, D.; Wei, X.; Weinstein, L.B.; Yurov, M.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z.W.; Zonta, I.

    2014-08-01T23:59:59.000Z

    Exclusive neutral-pion electroproduction (ep-->e'p'pi0) was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections d4sigma/dtdQ2dxBdphipi and structure functions sigmaT+epsilonsigmaL,sigmaTT and ?LT as functions of t were obtained over a wide range of Q2 and xB. The data are compared with Regge and handbag theoretical calculations. Analyses in both frameworks find that a large dominance of transverse processes is necessary to explain the experimental results. For the Regge analysis it is found that the inclusion of vector meson rescattering processes is necessary to bring the magnitude of the calculated and measured structure functions into rough agreement. In the handbag framework, there are two independent calculations, both of which appear to roughly explain the magnitude of the structure functions in terms of transversity generalized parton distributions.

  20. The large-area hybrid-optics CLAS12 RICH detector: Tests of innovative components

    SciTech Connect (OSTI)

    Contalbrigo, M.; Baltzell, N.; Benmokhtar, F.; Barion, L.; Cisbani, E.; El Alaoui, A.; Hafidi, K.; Hoek, M.; Kubarovsky, V.; Lagamba, L.; Lucherini, V.; Malaguti, R.; Mirazita, M.; Montgomery, R.; Movsisyan, A.; Musico, P.; Orecchini, D.; Orlandi, A.; Pappalardo, L.L.; Pereira, S.; Perrino, R.; Phillips, J.; Pisano, S.; Rossi, P.; Squerzanti, S.; Tomassini, S.; Turisini, M.; Viticchiè, A.

    2014-07-01T23:59:59.000Z

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadronization and hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely packed and highly segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). The preliminary results of individual detector component tests and of the prototype performance at test-beams are reported here.

  1. Measurement of the nuclear multiplicity ratio or image hadronization at CLAS

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Daniel, A; Brooks, W K; Hakobyan, H; Adhikari, K P; Adikaram, D; Aghasyan, M; Amarian, M; Anghinolfi, M; Avakian, H; Baghdasryan, H; Battaglieri, M; Batourine, V; Bedlinskiy, I; Bennett, R P; Biselli, A S; Bookwalter, C; Briscoe, W J; Burkert, V D; Carman, D S; Casey, L; Celentanot, A; Chandavar, S; Cole, P L; Contalbrigo, M; Crede, V; D' Angelou, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Dey, B; Dickson, R; Djalali, C; Dodge, G E; Doughty, D; Egiyan, H; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Gabrielyan, M Y; Gevorgyan, N; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Gohn, W; Golovatch, E; Gothe, R W; Griffioen, K A; Guidal, M; Guo, L; Hanretty, C; Heddle, D; Holtrop, M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jawalkar, S S; Jo, H S; Joo, K; Kalantarian, N; Keller, D; Khandaker, M; Khetarpal, P; Kim, A; Kim, W; Klein, A; Klein, F J; Kubarovsky, V; Kuleshov, S V; Kuznetsov, V; Lu, H Y; MacGregor, I.J.D.; Mao, Y; Markov, N; Mayer, M; McAndrew, J; McKinnon, B; Meyer, C A; Mine, T; Mirazita, M; Mokeev, V; Moutard, H; Munevar, E; Nadel-Turonski, P; Ni, A; Niccolai, S; Niculescux, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Paolone, M; Pappalardor, L; Paremuzyan, R; Park, K; Pasyuk, E; Anefalos Pereira, S; Phelps, E; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Protopopescu, D; Rauem, B A; Ricco, G; Rimal, D; Ripani, M; Rosner, G; Rossi, P; Sabatie, F; Saini, M S; Salgado, C; Schott, D; Schumacher, R A; Seraydaryan, H; Sharabian, Y G; Smith, G D; Soberg, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Strauch, S; Taiuti, M; Tang, W; Taylor, C E; Tkachenko, S; Ungaro, M; Vernarsky, B; Vineyard, M F; Voskanyan, H; Voutier, E; Watts, D P; Weinstein, L B; Weygand, D P; Wood, M H; Zana, L; Zachario, N; Zhao, B

    2011-11-30T23:59:59.000Z

    The influence of cold nuclear matter on lepto-production of hadrons in semi-inclusive deep inelastic scattering is measured using the CLAS detector in Hall B at Jefferson Lab and a 5.014 GeV electron beam. We report the View the MathML source multiplicity ratios for targets of C, Fe, and Pb relative to deuterium as a function of the fractional virtual photon energy z transferred to the View the MathML source and the transverse momentum squared View the MathML source of the View the MathML source. We find that the multiplicity ratios for View the MathML source are reduced in the nuclear medium at high z and low View the MathML source, with a trend for the View the MathML source transverse momentum to be broadened in the nucleus for large View the MathML source.

  2. Measurement of the nuclear multiplicity ratio for $K^0_s$ hadronization at CLAS

    E-Print Network [OSTI]

    A. Daniel; K. Hicks; W. K. Brooks; H. Hakobyan; CLAS Collaboration

    2011-11-10T23:59:59.000Z

    The influence of cold nuclear matter on lepto-production of hadrons in semi-inclusive deep inelastic scattering is measured using the CLAS detector in Hall B at Jefferson Lab and a 5.014 GeV electron beam. We report the $K_s^0$ multiplicity ratios for targets of C, Fe, and Pb relative to deuterium as a function of the fractional virtual photon energy $z$ transferred to the $K_s^0$ and the transverse momentum squared $p_{T}^2$ of the $K_s^0$. We find that the multiplicity ratios for $K^0_s$ are reduced in the nuclear medium at high $z$ and low $p_{T}^2$, with a trend for the $K^0_s$ transverse momentum to be broadened in the nucleus for large $p_{T}^2$.

  3. abramov juhendajad eero: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    modeling (C. D'Andrea and I. Emiris); for the clas- sification of coupled integrable. Fortuna, P. Gianni and B. Trager); on multi- variate rational function decomposition over an...

  4. Transverse Polarization of $?^{+}(1189)$ in Photoproduction on a Hydrogen Target in CLAS

    E-Print Network [OSTI]

    C. S. Nepali; M. Amaryan; K. P. Adhikari; M. Aghasyan; S. Anefalos Pereira; H. Baghdasaryan; J. Ball; M. Battaglieri; V. Batourine; I. Bedlinskiy; A. S. Biselli; J. Bono; S. Boiarinov; W. J. Briscoe; S. Bültmann; V. D. Burkert; D. S. Carman; A. Celentano; S. Chandavar; G. Charles; P. L. Cole; P. Collins; M. Contalbrigo; V. Crede; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; D. Doughty; R. Dupre; A. El Alaoui; L. El Fassi; G. Fedotov; S. Fegan; R. Fersch; J. A. Fleming; M. Y. Gabrielyan; N. Gevorgyan; K. L. Giovanetti; F. X. Girod; D. I. Glazier; J. T. Goetz; W. Gohn; E. Golovatch; R. W. Gothe; K. A. Griffioen; M. Guidal; N. Guler; K. Hafidi; H. Hakobyan; C. Hanretty; N. Harrison; D. Heddle; K. Hicks; D. Ho; M. Holtrop; C. E. Hyde; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; E. L. Isupov; H. S. Jo; D. Keller; M. Khandaker; P. Khetarpal; A. Kim; W. Kim; A. Klein; F. J. Klein; S. Koirala; V. Kubarovsky; S. E. Kuhn; S. V. Kuleshov; N. D. Kvaltine; H. Y. Lu; I . J . D. MacGregor; N. Markov; M. Mayer; B. McKinnon; T. Mineeva; M. Mirazita; V. Mokeev; R. A. Montgomery; E. Munevar; C. Munoz Camacho; P. Nadel-Turonski; S. Niccolai; G. Niculescu; I. Niculescu; M. Osipenko; A. I. Ostrovidov; L. L. Pappalardo; R. Paremuzyan; K. Park; S. Park; E. Pasyuk; E. Phelps; J. J. Phillips; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; S. Procureur; D. Protopopescu; A. J. R. Puckett; B. A. Raue; D. Rimal; M. Ripani; B. G. Ritchie; G. Rosner; P. Rossi; F. Sabatié; M. S. Saini; C. Salgado; D. Schott; R. A. Schumacher; E. Seder; H. Seraydaryan; Y. G. Sharabian; G. D. Smith; D. I. Sober; D. Sokhan; S. S. Stepanyan; S. Stepanyan; I. I. Strakovsky; S. Strauch; M. Taiuti; W. Tang; C. E. Taylor; Ye Tian; S. Tkachenko; B. Torayev; B. Vernarsky; A. V. Vlassov; H. Voskanyan; E. Voutier; N. K. Walford; D. P. Watts; L. B. Weinstein; D. P. Weygand; N. Zachariou; L. Zana; J. Zhang; Z. W. Zhao; I. Zonta; J. Zhang

    2013-02-02T23:59:59.000Z

    Experimental results on the $\\Sigma^+(1189)$ hyperon transverse polarization in photoproduction on a hydrogen target using the CLAS detector at Jefferson laboratory are presented. The $\\Sigma^+(1189)$ was reconstructed in the exclusive reaction $\\gamma+p\\rightarrow K^{0}_{S} + \\Sigma^+(1189)$ via the $\\Sigma^{+} \\to p \\pi^{0}$ decay mode. The $K^{0}_S$ was reconstructed in the invariant mass of two oppositely charged pions with the $\\pi^0$ identified in the missing mass of the detected $p\\pi^+\\pi^-$ final state. Experimental data were collected in the photon energy range $E_{\\gamma}$ = 1.0-3.5 GeV ($\\sqrt{s}$ range 1.66-2.73 GeV). We observe a large negative polarization of up to 95%. As the mechanism of transverse polarization of hyperons produced in unpolarized photoproduction experiments is still not well understood, these results will help to distinguish between different theoretical models on hyperon production and provide valuable information for the searches of missing baryon resonances.

  5. Exclusive $?^0$ electroproduction at $W>2$ GeV with CLAS

    E-Print Network [OSTI]

    I. Bedlinskiy; V. Kubarovsky; S. Niccolai; P. Stoler; K. P. Adhikari; M. D. Anderson; S. Anefalos Pereira; H. Avakian; J. Ball; N. A. Baltzell; M. Battaglieri; V. Batourine; A. S. Biselli; S. Boiarinov; J. Bono; W. J. Briscoe; W. K. Brooks; V. D. Burkert; D. S. Carman; A. Celentano; S. Chandavar; L. Colaneri; P. L. Cole; M. Contalbrigo; O. Cortes; V. Crede; A. D'Angelo; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; D. Doughty; R. Dupre; H. Egiyan; A. El Alaoui; L. El Fassi; L. Elouadrhiri; P. Eugenio; G. Fedotov; S. Fegan; J. A. Fleming; T. A. Forest; B. Garillon; M. Gar\\c con; G. Gavalian; N. Gevorgyan; Y. Ghandilyan; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; E. Golovatch; R. W. Gothe; K. A. Griffioen; B. Guegan; L. Guo; K. Hafidi; H. Hakobyan; N. Harrison; M. Hattawy; K. Hicks; M. Holtrop; D. G. Ireland; B. S. Ishkhanov; E. L. Isupov; D. Jenkins; H. S. Jo; K. Joo; D. Keller; M. Khandaker; A. Kim; W. Kim; A. Klein; F. J. Klein; S. Koirala; S. E. Kuhn; S. V. Kuleshov; P. Lenisa; W. I. Levine; K. Livingston; H. Y. Lu; I . J . D. MacGregor; N. Markov; M. Mayer; B. McKinnon; M. Mirazita; V. Mokeev; R. A. Montgomery; C. I. Moody; H. Moutarde; A Movsisyan; C. Munoz Camacho; P. Nadel-Turonski; I. Niculescu; M. Osipenko; A. I. Ostrovidov; L. L. Pappalardo; K. Park; S. Park; E. Pasyuk; E. Phelps; W. Phelps; J. J. Phillips; S. Pisano; O. Pogorelko; J. W. Price; Y. Prok; D. Protopopescu; S. Procureur; A. J. R. Puckett; B. A. Raue; M. Ripani; B. G. Ritchie; A. Rizzo; P. Rossi; P. Roy; F. Sabatié; C. Salgado; D. Schott; R. A. Schumacher; E. Seder; I. Senderovich; Y. G. Sharabian; A. Simonyan; G. D. Smith; D. I. Sober; D. Sokhan; S. S. Stepanyan; S. Strauch; V. Sytnik; W. Tang; Ye Tian; M. Ungaro; A. V. Vlassov; H. Voskanyan; E. Voutier; N. K. Walford; D. Watts; X. Wei; L. B. Weinstein; M. Yurov; N. Zachariou; L. Zana; J. Zhang; Z. W. Zhao; I. Zonta; for the CLAS Collaboration

    2014-05-05T23:59:59.000Z

    Exclusive neutral-pion electroproduction ($ep\\to e^\\prime p^\\prime \\pi^0$) was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections $d^4\\sigma/dtdQ^2dx_Bd\\phi_\\pi$ and structure functions $\\sigma_T+\\epsilon\\sigma_L, \\sigma_{TT}$ and $\\sigma_{LT}$ as functions of $t$ were obtained over a wide range of $Q^2$ and $x_B$. The data are compared with Regge and handbag theoretical calculations. Analyses in both frameworks find that a large dominance of transverse processes is necessary to explain the experimental results. For the Regge analysis it is found that the inclusion of vector meson rescattering processes is necessary to bring the magnitude of the calculated and measured structure functions into rough agreement. In the handbag framework, there are two independent calculations, both of which appear to roughly explain the magnitude of the structure functions in terms of transversity generalized parton distributions.

  6. Beyond the born approximation: Measuring the two-photon exchange effect at CLAS

    SciTech Connect (OSTI)

    Robert Paul Bennett

    2012-04-01T23:59:59.000Z

    Recent results from experiments at Jefferson Laboratory, Newport News VA, which measured the ratio of the electric to magnetic form factors of the proton, G{sub E}/G{sub M}, have forced us to reexamine the single photon exchange approximation in lepton-proton elastic scattering. Discrepancies between the ratio obtained via the time-tested Rosenbluth separation method and newer polarization transfer measurements, which differ by as much as a factor of three, may be resolved by considering the effect of two photon exchange (TPE) processes. The CLAS TPE experiment at Jefferson Laboratory, will determine the effect of two-photon exchange in elastic lepton-proton scattering by precisely measuring the ratio of positron-proton to electron-proton elastic cross sections over a large kinematic range (0.1 < {xi} < 0.96, 0.2 {ge} Q{sup 2} {le} 2.0 GeV{sup 2}). We accomplish this by directing the 5.5 GeV primary electron beam, provided by the Continuous Electron Beam Accelerator Facility (CEBAF), onto a set of radiators and converters to produce simultaneous and identical beams of electron and positrons which collide with our proton target. Acceptance and efficiency concerns are minimized by only considering the ratios of the elastic cross sections and by switching polarity of magnets in the beamline and the spectrometer. Guided by the results of a short 2006 test run and extensive GEANT based modeling, new shielding and beamline components were designed to maximize luminosity. We took data from November 2010 - February 2011. The unique experimental design and challenges of the TPE experiment and the current analysis status will be presented.

  7. Experimental study of the P??(1440) and D??(1520) resonances from the CLAS data on ep?e'????p'

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mokeev, V. I.; Burkert, V. D.; Elouadrhiri, L.; Fedotov, G. V.; Golovatch, E. N.; Gothe, R. W.; Ishkhanov, B. S.; Isupov, E. L.; Adhikari, K. P.; Aghasyan, M.; Anghinolfi, M.; Avakian, H.; Baghdasaryan, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Bookwalter, C.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Carman, D. S.; Celentano, A.; Charles, G.; Cole, P. L.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Daniel, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; El Alaoui, A.; Eugenio, P.; Fegan, S.; Fradi, A.; Giovanetti, K. L.; Girod, F. X.; Gohn, W.; Graham, L.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Hicks, K.; Ho, D.; Holtrop, M.; Ilieva, Y.; Ireland, D. G.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, A.; Kubarovsky, V.; Kuleshov, S. V.; Kvaltine, N. D.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Mao, Y.; Markov, N.; Martinez, D.; Mayer, M.; McKinnon, B.; Meyer, C. A.; Mineeva, T.; Mirazita, M.; Moutarde, H.; Munevar, E.; Nadel-Turonski, P.; Nepali, C. S.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Park, S.; Pasyuk, E.; Pereira, S. Anefalos; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Raue, B. A.; Ricco, G.; Rimal, D.; Ripani, M.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, G. D.; Smith, L. C.; Sober, D. I.; Sokhan, D.; Stepanyan, S.; Stepanyan, S. S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Tang, W.; Taylor, C. E.; Tian, Ye; Tkachenko, S.; Trivedi, A.; Ungaro, M.; Vineyard, M. F.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Wood, M. H.; Zachariou, N.; Zhao, Z. W.; Zonta, I.

    2012-09-01T23:59:59.000Z

    The transition helicity amplitudes from the proton ground state to the P??(1440) and D??(1520) excited states (?vpN* electrocouplings) were determined from the analysis of nine independent one-fold differential ????p electroproduction cross sections off a proton target, taken with CLAS at photon virtualities of 0.25vpN* electrocouplings offers clear evidence for the reliable extraction of these fundamental quantities from meson-electroproduction data. This analysis also led to the determination of the long-awaited hadronic branching ratios for the D??(1520) decay into ?? (24%–32%) and N? (8%–17%).

  8. Differential cross section and recoil polarization measurements for the gamma p to K+ Lambda reaction using CLAS at Jefferson Lab

    E-Print Network [OSTI]

    M. E. McCracken; M. Bellis; C. A. Meyer; M. Williams; for the CLAS Collaboration

    2009-12-23T23:59:59.000Z

    We present measurements of the differential cross section and Lambda recoil polarization for the gamma p to K+ Lambda reaction made using the CLAS detector at Jefferson Lab. These measurements cover the center-of-mass energy range from 1.62 to 2.84 GeV and a wide range of center-of-mass K+ production angles. Independent analyses were performed using the K+ p pi- and K+ p (missing pi -) final-state topologies; results from these analyses were found to exhibit good agreement. These differential cross section measurements show excellent agreement with previous CLAS and LEPS results and offer increased precision and a 300 MeV increase in energy coverage. The recoil polarization data agree well with previous results and offer a large increase in precision and a 500 MeV extension in energy range. The increased center-of-mass energy range that these data represent will allow for independent study of non-resonant K+ Lambda photoproduction mechanisms at all production angles.

  9. Single and double spin asymmetries for deeply virtual Compton scattering measured with CLAS and a longitudinally polarized proton target

    E-Print Network [OSTI]

    Pisano, S; Niccolai, S; Seder, E; Guidal, M; Mirazita, M

    2015-01-01T23:59:59.000Z

    Single-beam, single-target, and double-spin asymmetries for hard exclusive photon production on the proton $\\vec{e}\\vec{p} \\to e' p'\\gamma$ are presented. The data were taken at Jefferson Lab using the CLAS detector and a longitudinally polarized ${}^{14}$NH$_3$ target. The three asymmetries were measured in 165 4-dimensional kinematic bins, covering the widest kinematic range ever explored simultaneously for beam and target-polarization observables in the valence quark region. The kinematic dependences of the obtained asymmetries are discussed and compared to the predictions of models of Generalized Parton Distributions. The measurement of three DVCS spin observables at the same kinematic points allows a quasi-model-independent extraction of the imaginary parts of the $H$ and $\\tilde{H}$ Compton Form Factors, which give insight into the electric and axial charge distributions of valence quarks in the proton.

  10. Single and double spin asymmetries for deeply virtual Compton scattering measured with CLAS and a longitudinally polarized proton target

    E-Print Network [OSTI]

    S. Pisano; A. Biselli; S. Niccolai; E. Seder; M. Guidal; M. Mirazita; the CLAS Collaboration

    2015-01-28T23:59:59.000Z

    Single-beam, single-target, and double-spin asymmetries for hard exclusive photon production on the proton $\\vec{e}\\vec{p} \\to e' p'\\gamma$ are presented. The data were taken at Jefferson Lab using the CLAS detector and a longitudinally polarized ${}^{14}$NH$_3$ target. The three asymmetries were measured in 165 4-dimensional kinematic bins, covering the widest kinematic range ever explored simultaneously for beam and target-polarization observables in the valence quark region. The kinematic dependences of the obtained asymmetries are discussed and compared to the predictions of models of Generalized Parton Distributions. The measurement of three DVCS spin observables at the same kinematic points allows a quasi-model-independent extraction of the imaginary parts of the $H$ and $\\tilde{H}$ Compton Form Factors, which give insight into the electric and axial charge distributions of valence quarks in the proton.

  11. Experimental study of the P??(1440) and D??(1520) resonances from the CLAS data on ep?e'????p'

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mokeev, V. I.; Burkert, V. D.; Elouadrhiri, L.; Fedotov, G. V.; Golovatch, E. N.; Gothe, R. W.; Ishkhanov, B. S.; Isupov, E. L.; Adhikari, K. P.; Aghasyan, M.; et al

    2012-09-01T23:59:59.000Z

    The transition helicity amplitudes from the proton ground state to the P??(1440) and D??(1520) excited states (?vpN* electrocouplings) were determined from the analysis of nine independent one-fold differential ????p electroproduction cross sections off a proton target, taken with CLAS at photon virtualities of 0.25more »The successful description of a large body of data in dominant meson-electroproduction channels off protons with the same ?vpN* electrocouplings offers clear evidence for the reliable extraction of these fundamental quantities from meson-electroproduction data. This analysis also led to the determination of the long-awaited hadronic branching ratios for the D??(1520) decay into ?? (24%–32%) and N? (8%–17%).« less

  12. Quasi-free Cross Section Measurements at CLAS: ? D ? p ? ? ( p ) , ? D ? K ? ( 892 ) 0 ? ( p ) , ? D ? K + ? ? ( 1385 ) ? ( p )

    SciTech Connect (OSTI)

    Mattione, Paul [Carnegie Mellon U., JLAB

    2014-09-01T23:59:59.000Z

    Preliminary measurements of the quasi-free differential cross sections of the gD -->pp-(p), gD --> K*(892)0L(p), and gD --> K+S*(1385)?(p) reactions are shown using data from the Jefferson Lab Hall B CLAS g13 experiment. No experimental cross section data have yet been published on gD --> K*(892)0L(p), and the only published cross section data on gD --> K+S*(1385)?(p) are at forward angles, where t-channel K+ and K*+ exchanges are predicted to dominate. These data can be used to contribute to the search for the "missing" N* resonances, some of which are predicted to have non-negligible couplings to the excited strangeness channels. These cross sections are shown to be sizable compared to the ground-state channels, indicating that it is important to include excited channels in coupled-channels analyses used to extract the N* resonances. In addition, the gD --> pp?(p) data provide a significant increase to the world statistics, and will be used to study rescattering effects within the deuteron.

  13. First measurements of the {rho}{sup 3} spin density matrix elements in {gamma}p --> p {omega} using CLAS at JLAB

    SciTech Connect (OSTI)

    Vernarsky, Brian J. [Carnegie Mellon University, Pittsburgh, PA (United States)

    2014-01-01T23:59:59.000Z

    In an effort towards a ''complete'' experiment for the ? meson, we present studies from an experiment with an unpolarized target and a circularly polarized photon beam (g1c), carried out using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The experiment was analyzed using an extended maximum likelihood fit with partial wave amplitudes. New likelihood functions were calculated to account for the polarization of the photon beam. Both circular and linear polarizations are explored. The results of these fits are then used to project out the spin density matrix for the {omega}. First measurements of the {rho}{sup 3} spin density matrix elements will be presented using this method.

  14. Precise Determination of the Deuteron Spin Structure at Low to Moderate $Q^2$ with CLAS and Extraction of the Neutron Contribution

    E-Print Network [OSTI]

    N. Guler; R. G. Fersch; S. E. Kuhn; P. Bosted; K. A. Griffioen; C. Keith; R. Minehart; Y. Prok; K. P. Adhikari; D. Adikaram; M. J. Amaryan; M. D. Anderson; S. Anefalos Pereira; J. Ball; M. Battaglieri; V. Batourine; I. Bedlinskiy; W. J. Briscoe; W. K. Brooks; S. Bultmann; V. D. Burkert; D. S. Carman; A. Celentano; S. Chandavar; G. Charles; L. Colaneri; P. L. Cole; M. Contalbrigo; D. Crabb; V. Crede; A. D Angelo; N. Dashyan; A. Deur; C. Djalali; G. E. Dodge; R. Dupre; A. El Alaoui; L. El Fassi; L. Elouadrhiri; P. Eugenio; G. Fedotov; S. Fegan; A. Filippi; J. A. Fleming; T. A. Forest; B. Garillon; M. Garcon; N. Gevorgyan; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; E. Golovatch; R. W. Gothe; M. Guidal; L. Guo; K. Hafidi; H. Hakobyan; N. Harrison; M. Hattawy; K. Hicks; D. Ho; M. Holtrop; S. M. Hughes; C. E. Hyde; D. G. Ireland; B. S. Ishkhanov; E. L. Isupov; H. S. Jo; K. Joo; S. Joosten; D. Keller; M. Khandaker; A. Kim; W. Kim; A. Klein; F. J. Klein; V. Kubarovsky; S. V. Kuleshov; K. Livingston; H. Y. Lu; I. J. D. MacGregor; B. McKinnon; M. Mirazita; V. Mokeev; R. A. Montgomery; A Movsisyan; C. Munoz Camacho; P. Nadel-Turonski; L. A. Net; I. Niculescu; M. Osipenko; A. I. Ostrovidov; K. Park; E. Pasyuk; S. Pisano; O. Pogorelko; J. W. Price; S. Procureur; M. Ripani; A. Rizzo; G. Rosner; P. Rossi; P. Roy; F. Sabatie; C. Salgado; D. Schott; R. A. Schumacher; E. Seder; A. Simonyan; Iu. Skorodumina; D. Sokhan; N. Sparveris; I. I. Strakovsky; S. Strauch; V. Sytnik; Ye Tian; S. Tkachenko; M. Ungaro; E. Voutier; N. K. Walford; X. Wei; L. B. Weinstein; M. H. Wood; N. Zachariou; L. Zana; J. Zhang; Z. W. Zhao; I. Zonta

    2015-06-01T23:59:59.000Z

    We present the final results for the deuteron spin structure functions obtained from the full data set collected with Jefferson Lab's CLAS in 2000-2001. Polarized electrons with energies of 1.6, 2.5, 4.2 and 5.8 GeV were scattered from deuteron ($^{15}$ND$_3$) targets, dynamically polarized along the beam direction, and detected with CLAS. From the measured double spin asymmetry, the virtual photon absorption asymmetry $A_1^d$ and the polarized structure function $g_1^d$ were extracted over a wide kinematic range (0.05 GeV$^2 < Q^2 <$ 5 GeV$^2$ and 0.9 GeV $< W <$ 3 GeV). We use an unfolding procedure and a parametrization of the corresponding proton results to extract from these data the polarized structure functions $A_1^n$ and $g_1^n$ of the (bound) neutron, which are so far unknown in the resonance region, $W < 2$ GeV. We compare our final results, including several moments of the deuteron and neutron spin structure functions, with various theoretical models and expectations as well as parametrizations of the world data. The unprecedented precision and dense kinematic coverage of these data can aid in future extractions of polarized parton distributions, tests of perturbative QCD predictions for the quark polarization at large $x$, a better understanding of quark-hadron duality, and more precise values for higher-twist matrix elements in the framework of the Operator Product Expansion.

  15. Exclusive single pion electroproduction off the proton in the high-lying resonances at Q2 < 5 GeV2 from CLAS

    SciTech Connect (OSTI)

    Park, Kijun [ODU, JLAB

    2014-09-01T23:59:59.000Z

    The differential cross sections and structure functions for the exclusive electroproduction process ep --> e'n pi+ were measured in the range of the invariantmass for the np+ system 1.6 GeV lte W lte 2.0 GeV, and the photon virtuality 1.8 GeV2 lte Q2 lte 4.0 GeV2 using CLAS at Jefferson Lab. For the first time, these kinematics are probed in the exclusive p+ production from the protons with nearly full coverage in the azimuthal and polar angles of the np+ center-of-mass system. In this analysis, approximately 39,000 differential cross-section data points in terms of W, Q2, cosq theta* _ pi, and phi?_p-, were obtained. The preliminary differential cross section and structure function analyses are carried out, which allow us to extract the helicity amplitudes in high-lying resonances.

  16. Metadata Enrichment Services for the Europeana Digital Library

    E-Print Network [OSTI]

    Sebastiani, Fabrizio

    needs, thus allowing the tool to be effectively available to the multitude (2000+) of Europeana CPs. 1 to enrich the semantics of its own MRs prior to contributing them to Europeana. Different CPs are thus provenance. We view metadata enrichment as consisting of essentially two activities: clas- sification of MRs

  17. We have designed our algorithm to extract ridge and rubble features in multiyear ice. It has been developed for use with low-

    E-Print Network [OSTI]

    Fernandez, Thomas

    We have designed our algorithm to extract ridge and rubble features in multiyear ice. It has been the corresponding data prod- uct derived with the ice-roughness algorithm. We note that the algorithm was developed-of-sample. The boxed area shown in both these figures corresponds to the ice clas- sification map shown in Figure 1c

  18. The Patrick Elvander Taxonomy Trail

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Patrick Elvander Taxonomy Trail The Patrick Elvander Taxonomy Trail at the Arboretum at UC Santa: Taxonomy is partly the study of the naming and clas- sification of plants. For this more technical to produce a preview edition of the Manual in 1989. By establishing this Taxonomy trail as a memorial, we

  19. ISRAEL JOURNAL OF ECOLOGY & EVOLUTION, Vol. 52, 2006, pp. 1127 *Author to whom correspondence should be addressed. E-mail: yohay@technion.ac.il

    E-Print Network [OSTI]

    surrogates, environmental domains, K-means clas- sification; protected areas, Mt. Carmel INTROd. Evidence, in the form of direct comparison of these two surrogate types, is scarce. We conducted a direct comparison of the performance of a series of biological and environmental surrogates, at a local scale (300

  20. Bacteria and Surface Water Quality Standards Section 303(d) of the Clean Water Act requires that each state set

    E-Print Network [OSTI]

    bodies that support oyster harvesting, called oyster waters, have four clas- sifications which determineBacteria and Surface Water Quality Standards Section 303(d) of the Clean Water Act requires that each state set water quality standards to ensure all uses of a water body have the ap- propriate water

  1. MULTISCALE RANDOM PROJECTIONS FOR COMPRESSIVE CLASSIFICATION Marco F. Duarte,r

    E-Print Network [OSTI]

    of sam- pling and compression [1, 2]. CS enables the design of new kinds of compressive imaging systems ratio test; in the case of image classification, it exploits the fact that a set of images of a fixed- quires compressive image projections, we achieve high clas- sification rates using many fewer

  2. APPLICATION OF THE FUZZY MINMAX NEURAL NETWORK CLASSIFIER

    E-Print Network [OSTI]

    Blekas, Konstantinos

    . The fuzzy min­max classification network constitutes a promisimg pattern recognition approach that is based. Experimental results us­ ing the modified model on a difficult pattern recognition prob­ lem establishes of the fuzzy min­max clas­ sification neural network on a pattern recognition problem that involves both

  3. NeuDetect: A Neural Network Data Mining Wireless Network Intrusion Detection System

    E-Print Network [OSTI]

    Ezeife, Christie

    NeuDetect: A Neural Network Data Mining Wireless Network Intrusion Detection System C.I. Ezeife wireless intrusion detection systems, this paper presents a method of applying artificial neural networks mining clas- sification technique to wireless network intrusion detection system. The proposed system

  4. Dynamical Systems and Applications of Nonlinear Functional Analysis to Dynamical Systems

    E-Print Network [OSTI]

    Zhang, Meirong

    Dynamical Systems and Applications of Nonlinear Functional Analysis to Dynamical Systems Meirong consists of three parts. In Part 1 we introduce some basic concepts in dynamical systems, including limit sets, nonwandering sets, topological conjugacy, clas- sification of discrete dynamical systems under

  5. Measurement of the structure function of the nearly free neutron using spectator tagging in inelastic $^2$H(e, e'p)X scattering with CLAS

    E-Print Network [OSTI]

    S. Tkachenko; N. Baillie; S. E. Kuhn; J. Zhang; J. Arrington; P. Bosted; S. Bültmann; M. E. Christy; D. Dutta; R. Ent; H. Fenker; K. A. Griffioen; M. Ispiryan; N. Kalantarians; C. E. Keppel; W. Melnitchouk; V. Tvaskis; K. P. Adhikari; M. Aghasyan; M. J. Amaryan; S. Anefalos Pereira; H. Avakian; J. Ball; N. A. Baltzell; M. Battaglieri; I. Bedlinskiy; A. S. Biselli; W. J. Briscoe; W. K. Brooks; V. D. Burkert; D. S. Carman; A. Celentano; S. Chandavar; G. Charles; P. L. Cole; M. Contalbrigo; O. Cortes; V. Crede; A. D'Angelo; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; G. E. Dodge; D. Doughty; R. Dupre; H. Egiyan; A. El Alaoui; L. El Fassi; L. Elouadrhiri; P. Eugenio; G. Fedotov; J. A. Fleming; B. Garillon; N. Gevorgyan; Y. Ghandilyan; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; E. Golovatch; R. W. Gothe; M. Guidal; L. Guo; K. Hafidi; H. Hakobyan; C. Hanretty; N. Harrison; M. Hattawy; K. Hicks; D. Ho; M. Holtrop; C . E. Hyde; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; H. S. Jo; D. Keller; M. Khandaker; A. Kim; W. Kim; P. M. King; A. Klein; F. J. Klein; S. Koirala; V. Kubarovsky; S. V. Kuleshov; P. Lenisa; S. Lewis; K. Livingston; H. Lu; M. MacCormick; I. J. D. MacGregor; N. Markov; M. Mayer; B. McKinnon; T. Mineeva; M. Mirazita; V. Mokeev; R. A. Montgomery; H. Moutarde; C. Munoz Camacho; P. Nadel-Turonski; S. Niccolai; G. Niculescu; I. Niculescu; M. Osipenko; L. L. Pappalardo; R. Paremuzyan; K. Park; E. Pasyuk; J. J. Phillips; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; S. Procureur; D. Protopopescu; A. J . R. Puckett; D. Rimal; M. Ripani; A. Rizzo; G. Rosner; P. Rossi; P. Roy; F. Sabatié; D. Schott; R. A. Schumacher; E. Seder; I. Senderovich; Y. G. Sharabian; A. Simonyan; G. D. Smith; D. I. Sober; D. Sokhan; S. Stepanyan; S. S. Stepanyan; S. Strauch; W. Tang; M. Ungaro; A. V. Vlassov; H. Voskanyan; E. Voutier; N. K. Walford; D. Watts; X. Wei; L. B. Weinstein; M. H. Wood; L. Zana; I. Zonta

    2014-10-03T23:59:59.000Z

    Much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x. The Barely Off-shell Nucleon Structure (BONuS) experiment at Jefferson Lab measured the inelastic electron deuteron scattering cross section, tagging spectator protons in coincidence with the scattered electrons. This method reduces nuclear binding uncertainties significantly and has allowed for the first time a (nearly) model independent extraction of the neutron structure function. A novel compact radial time projection chamber was built to detect protons with momentum between 70 and 150 MeV/c. For the extraction of the free neutron structure function $F_{2n}$, spectator protons at backward angle and with momenta below 100 MeV/c were selected, ensuring that the scattering took place on a nearly free neutron. The scattered electrons were detected with Jefferson Lab's CLAS spectrometer. The extracted neutron structure function $F_{2n}$ and its ratio to the deuteron structure function $F_{2d}$ are presented in both the resonance and deep inelastic regions. The dependence of the cross section on the spectator proton momentum and angle is investigated, and tests of the spectator mechanism for different kinematics are performed. Our data set can be used to study neutron resonance excitations, test quark hadron duality in the neutron, develop more precise parametrizations of structure functions, as well as investigate binding effects (including possible mechanisms for the nuclear EMC effect) and provide a first glimpse of the asymptotic behavior of d/u as x goes to 1.

  6. The CLAS Forward Electromagnetic Calorimeter

    E-Print Network [OSTI]

    Thomas Jefferson National Accelerator Facility

    , calorimeter, calorimeters, calibration, scintillator 3 #12; 1 Overview The Continuous Beam Electron Accelerator Facility (CEBAF) at Je#11;erson Lab provides up to 6 GeV electrons to three experimental halls.A. Stephens c , T.Y. Tung, b;4 C. Zorn a a Thomas Je#11;erson National Accelerator Facility, Newport News, VA

  7. Measurement of differential cross sections and Cx and Cz for gamma photon-proton going to kaon-lambda baryon and gamma photon-proton going to kaon-sigma baryon using CLAS at Jefferson Lab

    SciTech Connect (OSTI)

    Robert Bradford

    2005-05-11T23:59:59.000Z

    This work presents several observables for the reactions ? p ? K+? and ? p ? K+?°. In addition to measuring differential cross sections, we have made first measurements of the double polarization observables Cx and Cz. Cx and C z characterize the transfer of polarization from the incident photon to the produced hyperons. Data were obtained at Jefferson Lab using a circularly polarized photon beam at endpoint energies of 2.4, 2.9, and 3.1 GeV. Events were detected with the CLAS spectrometer. In the ? channel, the cross sections support the recent observation of new resonant structure at W = 1900 MeV. Studies of the invariant cross section, dsdd show scaling behavior suggesting that the production mechanism becomes t-channel dominated near threshold at forward kaon angles. The double polarization observables show that the recoiling ? is almost maximally polarized along the direction of the incident photon from mid to forward kaon angles. While ?o differential cross sections are of the same magnitude as the ? differential cross sections, there is evidence of different physics dominating the production mechanism. The ?° invariant cross sections do not show the same t-scaling behavior present in the ? results. The double polarization observables indicate that the ?° is not polarized as strongly as the ?. They also fail to identify one preferred polarization axis. Complete interpretation of these results will rely on model calculations. Currently available isobar models obtain varying degrees of success while attempting to predict the double polarization observables. While the models are in better agreement with the differential cross sections, discrepancies with our cross sections indicate that they must be re-optimized in light of the new data. While the data suggest that a Regge model would provide a good description of K+? over most of the range in W, the available Regge calculation overstates the strength of the cross section and does not predict Cx and Cz correctly.

  8. Beam-Spin Asymmetry Measurement at CLAS

    SciTech Connect (OSTI)

    Aghasyan, M

    2009-08-04T23:59:59.000Z

    Beam Single Spin Asymmetries in single neutral semi-inclusive pion electroproduction off an unpolarized hydrogen target in the deep inelastic scattering regime (Q{sup 2}>1 GeV{sup 2}, W{sup 2}>4 GeV{sup 2}) have been measured using a polarized electron beam of 5.776 GeV with the CEBAF Large Acceptance Spectrometer at the Thomas Jefferson National Accelerator Facility (JLab). The measured kinematical dependences are compared with published data and existing theoretical predictions.

  9. Baryon spectroscopy with CLAS at Jefferson Lab

    SciTech Connect (OSTI)

    Eugene Pasyuk, CLAS Collaboration

    2012-04-01T23:59:59.000Z

    A substantial part of the experimental efforts at the experimental Hall-B of Jefferson Laboratory is dedicated to this studies of light baryon spectroscopy. In this report a general overview of the experimental capabilities in the Experimental Hall-B will be presented together with preliminary results of recent double polarization measurements and finally overall status of the program.

  10. Torus CLAS12-Superconducting Magnet Quench Analysis

    SciTech Connect (OSTI)

    Kashikhin, V S; Elouadhiri, L; Ghoshal, P K; Kashy, D; Makarov, A; Pastor, O; Quettier, L; Velev, G; Wiseman, M

    2014-06-01T23:59:59.000Z

    The JLAB Torus magnet system consists of six superconducting trapezoidal racetrack-type coils assembled in a toroidal configuration. These coils are wound with SSC-36 Nb-Ti superconductor and have the peak magnetic field of 3.6 T. The first coil manufacturing based on the JLAB design began at FNAL. The large magnet system dimensions (8 m diameter and 14 MJ of stored energy) dictate the need for quench protection. Each coil is placed in an aluminum case mounted inside a cryostat and cooled by 4.6 K supercritical helium gas flowing through a copper tube attached to the coil ID. The large coil dimensions and small cryostat thickness drove the design to challenging technical solutions, suggesting that Lorentz forces due to transport currents and eddy currents during quench and various failure scenarios are analyzed. The paper covers the magnet system quench analysis using the OPERA3d Quench code.

  11. CEBAF Large Acceptance Spectrometer (CLAS) Physics Database

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    A username and password are required to access and search the entire database. However, the Overview page provides links to detailed data pages for each of the experiments available for public access. There are many experiments with data that the public can freely access.

  12. Helium Compton Form Factor Measurements at CLAS

    SciTech Connect (OSTI)

    Voutier, Eric J.-M. [Laboratoire de Physique Subatomique et Cosmologie

    2013-07-01T23:59:59.000Z

    The distribution of the parton content of nuclei, as encoded via the generalized parton distributions (GPDs), can be accessed via the deeply virtual Compton scattering (DVCS) process contributing to the cross section for leptoproduction of real photons. Similarly to the scattering of light by a material, DVCS provides information about the dynamics and the spatial structure of hadrons. The sensitivity of this process to the lepton beam polarization allows to single-out the DVCS amplitude in terms of Compton form factors that contain GPDs information. The beam spin asymmetry of the $^4$He($\\vec {\\mathrm e}$,e$' \\gamma ^4$He) process was measured in the experimental Hall B of the Jefferson Laboratory to extract the real and imaginary parts of the twist-2 Compton form factor of the $^4$He nucleus. The experimental results reported here demonstrate the relevance of this method for such a goal, and suggest the dominance of the Bethe-Heitler amplitude to the unpolarized process in the kinematic range explored by the experiment.

  13. UNIVERSITY OF CALIFORNIA- BERKELEY UCRL CLAS CO

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram | Department HomeDialoguetANSWER OF THE2> D

  14. En.lighten Country Lighting Assessments (CLAs) | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directedAnnual SiteofEvaluating A PotentialJump to:Emminol Jump to: navigation, searchEmpresa deEn.lighten

  15. Study of Generalized Parton Distributions and Deeply Virtual Compton Scattering on the nucleon with the CLAS and CLAS12 detectors at the Jefferson Laboratory

    SciTech Connect (OSTI)

    Baptiste Guegan

    2012-11-01T23:59:59.000Z

    The exclusive leptoproduction of a real photon is considered to be the "cleanest" way to access the Generalized Parton Distribution (GPD). This process is called Deeply Virtual Compton Scattering (DVCS) lN {yields} lN{gamma} , and is sensitive to all the four GPDs. Measuring the DVCS cross section is one of the main goals of this thesis. In this thesis, we present the work performed to extract on a wide phase-space the DVCS cross-section from the JLab data at a beam energy of 6 GeV.

  16. Measurement of the neutron F2 structure function via spectator tagging with CLAS

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

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

    2012-04-06T23:59:59.000Z

    We report on the first measurement of the F2 structure function of the neutron from semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ? 100 degrees relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F2n data collected cover the nucleon resonance and deep-inelastic regions over a wide range of x for 0.65 2 2, with uncertainties from nuclear corrections estimated to be less than a few percent. These measurements provide the first determination of the neutron to proton structure function ratio F2n/F2p at 0.2 ?< x ?< 0.8, essentially free of nuclear corrections.

  17. Measurement of the neutron F2 structure function via spectator tagging with CLAS

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Baillie, N; Zhang, J; Bosted, P; Bultmann, S; Christy, M E; Fenker, H; Griffioen, K A; Keppel, C E; Kuhn, S E; Melnitchouk, W; et al

    2012-04-06T23:59:59.000Z

    We report on the first measurement of the F2 structure function of the neutron from semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ? 100 degrees relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F2n data collected cover the nucleon resonance and deep-inelastic regions over a wide range of x for 0.65 2 2, with uncertainties from nuclear corrections estimated to be less thanmore »a few percent. These measurements provide the first determination of the neutron to proton structure function ratio F2n/F2p at 0.2 ?« less

  18. Deeply virtual Compton scattering on longitudinally polarized protons and neutrons at CLAS

    E-Print Network [OSTI]

    Silvia Niccolai; for the CLAS Collaboration

    2012-07-13T23:59:59.000Z

    This paper focuses on a measurement of deeply virtual Compton scattering (DVCS) performed at Jefferson Lab using a nearly-6-GeV polarized electron beam, two longitudinally polarized (via DNP) solid targets of protons (NH3) and deuterons (ND3) and the CEBAF Large Acceptance Spectrometer. Here, preliminary results for target-spin asymmetries and double (beam-target) asymmetries for proton DVCS, as well as a very preliminary extraction of beam-spin asymmetry for neutron DVCS, are presented and linked to Generalized Parton Distributions.

  19. Deeply virtual Compton scattering on longitudinally polarized protons and neutrons at CLAS

    SciTech Connect (OSTI)

    Silvia Niccolai

    2012-04-01T23:59:59.000Z

    This paper focuses on a measurement of deeply virtual Compton scattering (DVCS) performed at Jefferson Lab using a nearly-6-GeV polarized electron beam, two longitudinally polarized (via DNP) solid targets of protons (NH{sub 3}) and deuterons (ND{sub 3}) and the CEBAF Large Acceptance Spectrometer. Here, preliminary results for target-spin asymmetries and double (beam-target) asymmetries for proton DVCS, as well as a very preliminary extraction of beam-spin asymmetry for neutron DVCS, are presented and linked to Generalized Parton Distributions.

  20. The Meson Spectroscopy Program Using the Forward Tagger with CLAS12 at Jefferson Lab

    SciTech Connect (OSTI)

    Fegan, Stuart [INFN-GENOVA

    2014-11-01T23:59:59.000Z

    The 12 GeV upgrade to the Continuous Electron Beam Accelerator Facility (CEBAF) will enable a new generation of experiments in hadronic nuclear physics at Jefferson Lab, seeking to address fundamental questions in QCD. For example, confirming the existence of exotic states, suggested by both quark models and lattice calculations, would allow gluonic degrees of freedom to be explored, and may help explain the role played by gluons in the QCD interaction. In Experimental Hall B, meson spectroscopy (the MesonEx experiment) will be performed using low Q2 electron scattering to produce quasi-real photons. The scattered electron is detected at small angles by the Forward Tagger device, determining the properties of the photon on an event-by-event basis. This technique has notable advantages over real photon beams, and over hadronic beam experiments, where most experimental data exists. This article will focus on the development of the Forward Tagger by the INFN Genova group, and the proposed MesonEx experiment.

  1. Measurement of the neutron F2 structure function via spectator tagging with CLAS

    E-Print Network [OSTI]

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

    2012-05-14T23:59:59.000Z

    We report on the first measurement of the F2 structure function of the neutron from semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to < 100 MeV and their angles to < 100 degrees relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F2n data collected cover the nucleon resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65 < Q2 < 4.52 GeV2, with uncertainties from nuclear corrections estimated to be less than a few percent. These measurements provide the first determination of the neutron to proton structure function ratio F2n/F2p at 0.2 < x < 0.8 with little uncertainty due to nuclear effects.

  2. SINGLE # + ELECTROPRODUCTION IN THE FIRST AND SECOND RESONANCE REGIONS USING CLAS

    E-Print Network [OSTI]

    Lewis, Robert Michael

    . . . . . . . . . . . . . . . . . . . . . . 21 2.1 Continuous Electron Beam Accelerator Facility . . . . . . . . . . . 21 2.2 General Description and Processing . . . . . . . . . . . . . . . . . . . 56 4.2 Electron Identification

  3. Measurement of the neutron F2 structure function via spectator tagging with CLAS

    SciTech Connect (OSTI)

    Baillie, N; Zhang, J; Bosted, P; Bultmann, S; Christy, M E; Fenker, H; Griffioen, K A; Keppel, C E; Kuhn, S E; Melnitchouk, W; Tvaskis, V; Adhikari, K P; Adikaram, D; Aghasyan, M; Amaryan, M J; Anghinolfini, M; Arrington, J; Avakian, H; Baghdasaryan, H; Battaglieri, M; Biselli, A A; Branford, D; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Cole, P L; Contalbrigo, M; Crede, V; D& #x27; Angelo, A; Daniel, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Dey, B; Djalali, C; Dodge, G; Domingo, J; Doughty, D; Dupre, R; Dutta, D; Ent, R; Egiyan, H; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Fradi, A; Gabrielyan, M Y; Gevorgyan, N; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Gohn, W; Golovatch, E; Gothe, R W; Graham, L; Guegan, B; Guidal, M; Guler, N; Guo, L; Hafidi, K; Heddle, D; Hicks, K; Holtrop, M; Hungerford, E; Hyde, C E; Ilieva, Y; Ireland, D G; Ispiryan, M; Isupov, E L; Jawalkar, S S; Jo, H S; Kalantarians, N; Khandaker, M; Khetarpal, P; Kim, A; Kim, W; King, P M; Klein, A; Klein, F J; Klimenko, A; Kubarovsky, V; Kuleshov, S V; Kvaltine, N D; Livingston, K; Lu, H Y; MacGregor, I.J. D; Mao, Y; Markov, N; McKinnon, B; Mineeva, T; Morrison, B; Moutarde, H; Munevar, E; Nadel-Turonski, P; Ni, A; Niccolai, S; Niculescu, I; Niculescu, G; Osipenko, M; Ostrovidov, A I; Pappalardo, L; Park, K; Park, S; Pasyuk, E; Anefalos Pereira, S; Pisano, S; Pozdniakov, S; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Raue, B A; Ricco, G; Rimal, D; Ripani, M; Rosner, G; Rossi, P; Sabatie, F; Saini, M S; Salgado, C; Schott, D; Schumacher, R A; Seder, E; Sharabian, Y G; Sober, D I; Sokhan, D; Stepanyan, S; Stepanyan, S S; Stoler, P; Strauch, S; Taiuti, M; Tang, W; Ungaro, M; Vineyard, M F; Voutier, E; Watts, D P; Weinstein, L B; Weygand, D P; Wood, M H; Zana, L

    2012-04-06T23:59:59.000Z

    We report on the first measurement of the F2 structure function of the neutron from semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ?< 100 MeV and their angles to ?> 100 degrees relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F2n data collected cover the nucleon resonance and deep-inelastic regions over a wide range of x for 0.65 < Q2 < 4.52 GeV2, with uncertainties from nuclear corrections estimated to be less than a few percent. These measurements provide the first determination of the neutron to proton structure function ratio F2n/F2p at 0.2 ?< x ?< 0.8, essentially free of nuclear corrections.

  4. Spectroscopy of exotic baryons with CLAS: search for ground and first excited states

    SciTech Connect (OSTI)

    M. Battaglieri

    2004-07-20T23:59:59.000Z

    In the last year many Collaborations reported about the evidence of a possible pentaquark state but so far the results are not yet conclusive. New dedicated experiments with higher statistics and precision are necessary to confirm the pentaquark existence and its properties. In this contribution, I will report about a new photoproduction experiment on a proton target, the so-called 'G11' experiment, just performed in the Hall-B at Jefferson Lab that collected ten times the existing statistics.

  5. CLAS Associate Director John Frechione suffering the adverse March weather in

    E-Print Network [OSTI]

    Machery, Edouard

    , University of California, Irvine) at the Latin American Social and Public Policy Conference. (See page 3, Ecuador, Argentina, Brazil, and Poland and has presented man- agement seminars in Turkey, Slovakia

  6. Final Report for Bio-Inspired Approaches to Moving-Target Defense Strategies

    SciTech Connect (OSTI)

    Fink, Glenn A.; Oehmen, Christopher S.

    2012-09-01T23:59:59.000Z

    This report records the work and contributions of the NITRD-funded Bio-Inspired Approaches to Moving-Target Defense Strategies project performed by Pacific Northwest National Laboratory under the technical guidance of the National Security Agency’s R6 division. The project has incorporated a number of bio-inspired cyber defensive technologies within an elastic framework provided by the Digital Ants. This project has created the first scalable, real-world prototype of the Digital Ants Framework (DAF)[11] and integrated five technologies into this flexible, decentralized framework: (1) Ant-Based Cyber Defense (ABCD), (2) Behavioral Indicators, (3) Bioinformatic Clas- sification, (4) Moving-Target Reconfiguration, and (5) Ambient Collaboration. The DAF can be used operationally to decentralize many such data intensive applications that normally rely on collection of large amounts of data in a central repository. In this work, we have shown how these component applications may be decentralized and may perform analysis at the edge. Operationally, this will enable analytics to scale far beyond current limitations while not suffering from the bandwidth or computational limitations of centralized analysis. This effort has advanced the R6 Cyber Security research program to secure digital infrastructures by developing a dynamic means to adaptively defend complex cyber systems. We hope that this work will benefit both our client’s efforts in system behavior modeling and cyber security to the overall benefit of the nation.

  7. STATEMENT OF CONSIDERATIONS PETITION FOR ADVANCE WAIVER OF PATENT...

    Broader source: Energy.gov (indexed) [DOE]

    to provide significant information on carbon conversion with resulting gaSification product distribution. And finally developing a process design for a commercial...

  8. Patterns and processes in the evolutionary history of parrotfishes (Family Labridae)

    E-Print Network [OSTI]

    Bermingham, Eldredge

    Research Institute, Ancon, Balboa, Republic of Panama 3 School of Biological Sciences, University of the Linnean Society, 2012, ··, ··­··. ADDITIONAL KEYWORDS: adaptive radiation ­ evolution ­ sexual selection ­ speciation ­ reef fish. INTRODUCTION Adaptive radiations are episodes of phenotypic diver- sification

  9. Measurements of $ep \\to e^\\prime ?^+n$ at W = 1.6 - 2.0 GeV and extraction of nucleon resonance electrocouplings at CLAS

    E-Print Network [OSTI]

    K. Park; I. G. Aznauryan; V. D. Burkert; the CLAS collaboration

    2014-12-17T23:59:59.000Z

    Differential cross sections of the exclusive process $e p \\to e^\\prime \\pi^+ n$ were measured with good precision in the range of the photon virtuality $Q^2 = 1.8 - 4.5$ GeV$^2$, and the invariant mass range of the $\\pi^+ n$ final state W = 1.6 - 2.0 GeV using the CEBAF Large Acceptance Spectrometer. Data were collected with nearly complete coverage in the azimuthal and polar angles of the $n\\pi^+$ center-of-mass system. More than 37,000 cross section points were measured. The contributions of the isospin $I = {1\\over 2}$ resonances $N(1675){5\\over 2}^-$, $N(1680){5\\over 2}^+$ and $N(1710){1\\over 2}^+$ were extracted at different values of $Q^2$ using a single-channel, energy-dependent resonance amplitude analysis. Two different approaches, the unitary isobar model and the fixed-$t$ dispersion relations, were employed in the analysis. We observe significant strength of the $N(1675){5\\over 2}^-$ in the $A_{1/2}$ amplitude, which is in strong disagreement with quark models that predict both transverse amplitudes to be strongly suppressed. For the $N(1680){5\\over 2}^+$ we observe a slow changeover from the dominance of the $A_{3/2}$ amplitude at the real photon point ($Q^2=0$) to a $Q^2$ where $A_{1/2}$ begins to dominate. The scalar amplitude $S_{1/2}$ drops rapidly with $Q^2$ consistent with quark model prediction. For the $N(1710){1\\over 2}^+$ resonance our analysis shows significant strength for the $A_{1/2}$ amplitude at $Q^2 < 2.5$ GeV$^2$.

  10. Measurements of $ep \\to e^\\prime ?^+n$ at W = 1.6 - 2.0 GeV and extraction of nucleon resonance electrocouplings at CLAS

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Park, Kijun [ODU, JLAB; et. al.,; Aznauryan, I. G.; Burkert, V. D.; Adhikari, K. P.; Amaryan, M. J.; Pereira, S. Anefalos; Avakian, H.; Battaglieri, M.; Badui, R.; Bedlinskiy, I.; Biselli, A. S.; Bono, J.; Briscoe, W. J.; Brooks, W. K.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; Egiyan, H.; Alaoui, A. El; Elouadrhiri, L.; Fassi, L. El; Eugenio, P.; Fedotov, G.; Fegan, S.; Fersch, R.; Filippi, A.; Fleming, J. A.; Garillon, B.; Gar??on, M.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Joo, H.S.; Goetz, J. T.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hakobyan, H.; Hanretty, C.; Hattawy, M.; Hicks, K.; Holtrop, M.; Hughes, S. M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jenkins, D.; Jiang, H.; Jo, H. S.; Joo, K.; Joosten, S.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Kubarovsky, V.; Kuhn, S. E.; Kuleshov, S. V.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J.; Markov, N.; Martinez, D.; McKinnon, B.; Mokeev, V.; Montgomery, R. A.; Moutarde, H.; Camacho, C. Munoz; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Pasyuk, E.; Peng, P.; Phelps, W.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Price, J. W.; Procureur, S.; Prok, Y.; Protopopescu, D.; Puckett, A. J.; Raue, B. A.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabati??, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Sharabian, Y. G.; Simonyan, A.; Skorodumina, Iu.; Smith, E. S.; Smith, G. D.; Sparveris, N.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tang, W.; Taylor, C. E.; Tian, Ye; Trivedi, A.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.

    2015-04-01T23:59:59.000Z

    Differential cross sections of the exclusive process $e p \\to e^\\prime \\pi^+ n$ were measured with good precision in the range of the photon virtuality $Q^2 = 1.8 - 4.5$ GeV$^2$, and the invariant mass range of the $\\pi^+ n$ final state W = 1.6 - 2.0 GeV using the CEBAF Large Acceptance Spectrometer. Data were collected with nearly complete coverage in the azimuthal and polar angles of the $n\\pi^+$ center-of-mass system. More than 37,000 cross section points were measured. The contributions of the isospin $I = {1\\over 2}$ resonances $N(1675){5\\over 2}^-$, $N(1680){5\\over 2}^+$ and $N(1710){1\\over 2}^+$ were extracted at different values of $Q^2$ using a single-channel, energy-dependent resonance amplitude analysis. Two different approaches, the unitary isobar model and the fixed-$t$ dispersion relations, were employed in the analysis. We observe significant strength of the $N(1675){5\\over 2}^-$ in the $A_{1/2}$ amplitude, which is in strong disagreement with quark models that predict both transverse amplitudes to be strongly suppressed. For the $N(1680){5\\over 2}^+$ we observe a slow changeover from the dominance of the $A_{3/2}$ amplitude at the real photon point ($Q^2=0$) to a $Q^2$ where $A_{1/2}$ begins to dominate. The scalar amplitude $S_{1/2}$ drops rapidly with $Q^2$ consistent with quark model prediction. For the $N(1710){1\\over 2}^+$ resonance our analysis shows significant strength for the $A_{1/2}$ amplitude at $Q^2 < 2.5$ GeV$^2$.

  11. Measurement of the nearly free neutron structure function using spectator tagging in inelastic 2H(e,e'p s)X scattering with CLAS

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tkachenko, Svyatoslav; Baillie, Nathan; Kuhn, Sebastian; Zhang, J; Arrington, John; Bosted, Peter; Bueltmann, Stephen; Christy, Michael; Fenker, Howard; Griffioen, Keith; Kalantarians, Narbe; Keppel, Cynthia; Melnitchouk, Wolodymyr; Tvaskis, Vladas; Adhikari, Krishna; Aghasyan, Mher; Amaryan, Moskov; Anefalos Pereira, Sergio; Avagyan, Harutyun; Ball, Jacques; Baltzell, Nathan; Battaglieri, Marco; Bedlinskiy, Ivan; Biselli, Angela; Briscoe, William; Brooks, William; Burkert, Volker; Carman, Daniel; Celentano, Andrea; Chandavar, Shloka; Charles, Gabriel; Cole, Philip; Contalbrigo, Marco; Cortes, Olga; Crede, Volker; D'Angelo, Annalisa; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Deur, Alexandre; Djalali, Chaden; Dodge, Gail; Doughty, David; Dupre, Raphael; Egiyan, Hovanes; El Alaoui, Ahmed; El Fassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Fleming, Jamie; Garillon, Brice; Gevorgyan, Nerses; Ghandilyan, Yeranuhi; Gilfoyle, Gerard; Giovanetti, Kevin; Girod-Gard, Francois-Xavier; Goetz, John; Golovach, Evgeny; Gothe, Ralf; Guidal, Michel; Guo, Lei; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Harrison, Nathan; Hattawy, Mohammad; Hicks, Kenneth; Ho, Dao; Holtrop, Maurik; Hyde, Charles; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Jo, Hyon-Suk; Keller, Dustin; Khandaker, Mahbubul; Kim, Andrey; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Koirala, Suman; Kubarovsky, Valery; Kuleshov, Sergey; Lenisa, Paolo; Lewis, Stefanie; Livingston, Kenneth; Lu, H; MacCormick, Marion; MacGregor, Ian; Markov, Nikolai; Mayer, Michael; McKinnon, Bryan; Mineeva, Taisiya; Mirazita, Marco; Mokeev, Viktor; Montgomery, Rachel; MOUTARDE, Herve; Munoz Camacho, Carlos; Nadel-Turonski, Pawel; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria; Osipenko, Mikhail; Pappalardo, Luciano; Paremuzyan, Rafayel; Park, Kijun; Pasyuk, Eugene; Phillips, J J; Pisano, Silvia; Pogorelko, Oleg; Pozdniakov, Serguei; Price, J W; Procureur, Sebastien; Protopopescu, Dan; Puckett, Andrew; Rimal, Dipak; Ripani, Marco; Rizzo, Alessandro; Rosner, Guenther; Rossi, Patrizia; Roy, Priyashree; Sabatie, Franck; Schott, Diane; Schumacher, Reinhard; Seder, Erin; Senderovich, Igor; Sharabian, Youri; Simonyan, Ani; Smith, Gregory; Sober, Daniel; Sokhan, Daria; Stepanyan, Stepan; Stepanyan, Samuel; Strauch, Steffen; Tang, Wei; Ungaro, Maurizio; Vlasov, Alexander; Voskanyan, Hakob; VOUTIER, Eric; Walford, Natalie; Watts, Daniel; Wei, Xiangdong; Weinstein, Lawrence; Wood, Michael; Zana, Lorenzo; Zonta, Irene

    2014-04-01T23:59:59.000Z

    Much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x. As a consequence, the same data can lead to different conclusions, for example, about the behavior of the d quark distribution in the proton at large x.

  12. Measurements of $ep \\to e^\\prime ?^+n$ at W = 1.6 - 2.0 GeV and extraction of nucleon resonance electrocouplings at CLAS

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Park, Kijun; et. al.,; Aznauryan, I. G.; Burkert, V. D.; Adhikari, K. P.; Amaryan, M. J.; Pereira, S. Anefalos; Avakian, H.; Battaglieri, M.; Badui, R.; et al

    2015-04-01T23:59:59.000Z

    Differential cross sections of the exclusive process $e p \\to e^\\prime \\pi^+ n$ were measured with good precision in the range of the photon virtuality $Q^2 = 1.8 - 4.5$ GeV$^2$, and the invariant mass range of the $\\pi^+ n$ final state W = 1.6 - 2.0 GeV using the CEBAF Large Acceptance Spectrometer. Data were collected with nearly complete coverage in the azimuthal and polar angles of the $n\\pi^+$ center-of-mass system. More than 37,000 cross section points were measured. The contributions of the isospin $I = {1\\over 2}$ resonances $N(1675){5\\over 2}^-$, $N(1680){5\\over 2}^+$ and $N(1710){1\\over 2}^+$ were extracted atmore »different values of $Q^2$ using a single-channel, energy-dependent resonance amplitude analysis. Two different approaches, the unitary isobar model and the fixed-$t$ dispersion relations, were employed in the analysis. We observe significant strength of the $N(1675){5\\over 2}^-$ in the $A_{1/2}$ amplitude, which is in strong disagreement with quark models that predict both transverse amplitudes to be strongly suppressed. For the $N(1680){5\\over 2}^+$ we observe a slow changeover from the dominance of the $A_{3/2}$ amplitude at the real photon point ($Q^2=0$) to a $Q^2$ where $A_{1/2}$ begins to dominate. The scalar amplitude $S_{1/2}$ drops rapidly with $Q^2$ consistent with quark model prediction. For the $N(1710){1\\over 2}^+$ resonance our analysis shows significant strength for the $A_{1/2}$ amplitude at $Q^2 « less

  13. Measurement of the nearly free neutron structure function using spectator tagging in inelastic 2H(e,e'p s)X scattering with CLAS

    SciTech Connect (OSTI)

    Tkachenko, Svyatoslav; Baillie, Nathan; Kuhn, Sebastian; Zhang, J; Arrington, John; Bosted, Peter; Bueltmann, Stephen; Christy, Michael; Fenker, Howard; Griffioen, Keith; Kalantarians, Narbe; Keppel, Cynthia; Melnitchouk, Wolodymyr; Tvaskis, Vladas; Adhikari, Krishna; Aghasyan, Mher; Amaryan, Moskov; Anefalos Pereira, Sergio; Avagyan, Harutyun; Ball, Jacques; Baltzell, Nathan; Battaglieri, Marco; Bedlinskiy, Ivan; Biselli, Angela; Briscoe, William; Brooks, William; Burkert, Volker; Carman, Daniel; Celentano, Andrea; Chandavar, Shloka; Charles, Gabriel; Cole, Philip; Contalbrigo, Marco; Cortes, Olga; Crede, Volker; D'Angelo, Annalisa; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Deur, Alexandre; Djalali, Chaden; Dodge, Gail; Doughty, David; Dupre, Raphael; Egiyan, Hovanes; El Alaoui, Ahmed; El Fassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Fleming, Jamie; Garillon, Brice; Gevorgyan, Nerses; Ghandilyan, Yeranuhi; Gilfoyle, Gerard; Giovanetti, Kevin; Girod-Gard, Francois-Xavier; Goetz, John; Golovach, Evgeny; Gothe, Ralf; Guidal, Michel; Guo, Lei; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Harrison, Nathan; Hattawy, Mohammad; Hicks, Kenneth; Ho, Dao; Holtrop, Maurik; Hyde, Charles; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Jo, Hyon-Suk; Keller, Dustin; Khandaker, Mahbubul; Kim, Andrey; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Koirala, Suman; Kubarovsky, Valery; Kuleshov, Sergey; Lenisa, Paolo; Lewis, Stefanie; Livingston, Kenneth; Lu, H; MacCormick, Marion; MacGregor, Ian; Markov, Nikolai; Mayer, Michael; McKinnon, Bryan; Mineeva, Taisiya; Mirazita, Marco; Mokeev, Viktor; Montgomery, Rachel; MOUTARDE, Herve; Munoz Camacho, Carlos; Nadel-Turonski, Pawel; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria; Osipenko, Mikhail; Pappalardo, Luciano; Paremuzyan, Rafayel; Park, Kijun; Pasyuk, Eugene; Phillips, J J; Pisano, Silvia; Pogorelko, Oleg; Pozdniakov, Serguei; Price, J W; Procureur, Sebastien; Protopopescu, Dan; Puckett, Andrew; Rimal, Dipak; Ripani, Marco; Rizzo, Alessandro; Rosner, Guenther; Rossi, Patrizia; Roy, Priyashree; Sabatie, Franck; Schott, Diane; Schumacher, Reinhard; Seder, Erin; Senderovich, Igor; Sharabian, Youri; Simonyan, Ani; Smith, Gregory; Sober, Daniel; Sokhan, Daria; Stepanyan, Stepan; Stepanyan, Samuel; Strauch, Steffen; Tang, Wei; Ungaro, Maurizio; Vlasov, Alexander; Voskanyan, Hakob; VOUTIER, Eric; Walford, Natalie; Watts, Daniel; Wei, Xiangdong; Weinstein, Lawrence; Wood, Michael; Zana, Lorenzo; Zonta, Irene

    2014-04-01T23:59:59.000Z

    Much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x. As a consequence, the same data can lead to different conclusions, for example, about the behavior of the d quark distribution in the proton at large x.

  14. doi:10.1152/ajpheart.00806.2008 296:796-805, 2009. First published Jan 9, 2009;Am J Physiol Heart Circ Physiol

    E-Print Network [OSTI]

    Intrator, Nathan

    - sification; noninvasive monitoring THE MECHANICAL FUNCTION OF the cardiovascular system is gov- erned.physiology.orgDownloadedfrom #12;Respiratory modulation of heart sound morphology Guy Amit,1 Khuloud Shukha,2 Noam Gavriely,2 form 7 January 2009 Amit G, Shukha K, Gavriely N, Intrator N. Respiratory modulation of heart sound

  15. Open Archive TOULOUSE Archive Ouverte (OATAO) OATAO is an open access repository that collects the work of Toulouse researchers and

    E-Print Network [OSTI]

    Mailhes, Corinne

    by spark plasma sintering at 100 MPa, within the temperature range of 700­1500 C. Sintering at 700 C. Introduction Spark plasma sintering (SPS) has been used for rapid den- sification of different ceramic plasma sintering. Journal of the European Ceramic Society, vol. 31 (n° 6). pp. 1057-1066. ISSN 0955

  16. Tropical forests are both evolutionary cradles and museums of leaf beetle diversity

    E-Print Network [OSTI]

    Farrell, Brian D.

    in the genus Cephaloleia, we present evidence for (i) comparatively ancient Paleocene­Eocene adaptive radiation-specific diversification coincident with the Oligocene adaptive radiation of Cephaloleia host plants in the genus Heliconia, and (iii) relatively recent Miocene­Pliocene diver- sification coincident with the collision of the Panama

  17. Probabilistic Methods for Model Validation 

    E-Print Network [OSTI]

    Halder, Abhishek

    2014-05-01T23:59:59.000Z

    Instead of Moments or Sets . . . . . 6 1.3.4 Methodology and Organization . . . . . . . . . . . . . . . . . 8 1.4 Contributions of This Dissertation . . . . . . . . . . . . . . . . . . . . 9 2. UNCERTAINTY PROPAGATION FOR DETERMINISTIC FLOW . . . . 12 2...’s Density Function Based Model Fal- sification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 4.6 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 xv 5. CASE STUDY: F-16 CONTROLLER ROBUSTNESS VERIFICATION...

  18. Open Archive TOULOUSE Archive Ouverte (OATAO) OATAO is an open access repository that collects the work of Toulouse researchers and

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    a two-step process including an initial emul- sification of two immiscible fluids in static mixers emulsification in static mixers are then investigated. The hydrodynamic of the Deanhex reactor used is also process, the emulsion droplets obtained at the static mixer outlet are encapsulated firstly in the Deanhex

  19. Bernhard Mecking steps down as Hall B leader at Jefferson Lab...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Bernhard Mecking Jefferson Lab staff scientist Bernhard Mecking with the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B. Bernhard Mecking steps down as Hall B leader at...

  20. REVIEW OF PARTICLE PHYSICS

    E-Print Network [OSTI]

    Beringer, Juerg

    2013-01-01T23:59:59.000Z

    by CLAS and PrimEx at CEBAF, and by PANDA at GSI. Recently,Switzerland Bologna, Italy CEBAF CENG CERN CFPA Trombay,

  1. Update on adolescent immunization: pertussis, meningococcus, HPV, and the future.

    E-Print Network [OSTI]

    Yeh, S. H; Lieberman, J. M

    2007-01-01T23:59:59.000Z

    is a frequent cause of prolonged cough illness in adults andcold to clas- by almost 99% ? PERTUSSIS (WHOOPING COUGH) sicwhooping cough, depending on the degree of preexisting

  2. 2010 Research Opportunity Seed Fund Awards PI College (dept) Co-PIs College (dept) Title

    E-Print Network [OSTI]

    Wu, Dapeng Oliver

    COE (BME & MSE) Tan, Weihong CLAS (Chemistry) Jacob Jones COE (MSE) Solar Energy Harvesting Using (Microbiology) Mark Atkinson COM (Pathology) The Defining Characteristics of the Autoimmune Microbiome

  3. ESSENTIAL SKILLS (6-16 credit hours) Writing as Critical Thinking (3 credit hours)

    E-Print Network [OSTI]

    Gering, Jon C.

    (template) Aesthetic--Literature (3 credit hours) CLAS 261 Greek Literature in Translation CLAS 262 Roman Literature RUSS 340 Russian Drama RUSS 370 Survey of Russian Literature I RUSS 371 Survey of Russian Literature II RUSS 420 Modern Russian Novel RUSS 480 Major Russian Writers SPAN 460 Survey of Spanish

  4. Exclusive pi^0 electroproduction in the resonance region at high Q^2

    SciTech Connect (OSTI)

    M. Ungaro, K. Joo

    2012-04-01T23:59:59.000Z

    We present preliminary results from {pi}{sup 0} electroproduction data taken with CLAS at Jefferson Lab. These and other CLAS measurements, coupled with recent theoretical developments, will allow non-perturbative approaches to shed lights on the role of quarks and gluons in nuclei and address issues such as confinement and the non-zero quark mass in the chiral limit.

  5. Exclusive {pi}{sup 0},{eta} electroproduction in the resonance region at high Q{sup 2}

    SciTech Connect (OSTI)

    Ungaro, M.; Joo, K. [University of Connecticut, Storrs, CT, 06269 (United States)

    2011-10-24T23:59:59.000Z

    We present preliminary results from {pi}{sup 0} and {eta} electroproduction data taken with CLAS at Jefferson Lab. These and other CLAS measurements, coupled with recent theoretical developments, will allow non-perturbative approaches to shed lights on the role of quarks and gluons in nuclei and address issues such as confinement and the non-zero quark mass in the chiral limit.

  6. Studies of semi-inclusive and hard exclusive processes at Jlab

    SciTech Connect (OSTI)

    Harutyun Avagyan

    2008-06-19T23:59:59.000Z

    The main goal of experiments proposed for the {\\tt CLAS12} detector in conjunction with the 12-GeV CEBAF accelerator is the study of the nucleon through hard exclusive, semi-inclusive, and inclusive processes. This will provide new insights into nucleon dynamics at the elementary quark and gluon level. In this contribution we provide an overview of ongoing studies of the structure of nucleon in terms of quark and gluon degrees of freedom and future physics program planned with CLAS and {\\tt CLAS12}.

  7. Pentaquark Theta(+) production from the reaction gamma p ->pi K-+(-)Theta(+)

    E-Print Network [OSTI]

    Liu, W.; Ko, Che Ming; Kubarovsky, V.

    2004-01-01T23:59:59.000Z

    The cross section for theta(+) production from the reaction gammap-->pi(+)K(-)theta(+), which was observed in the CLAS experiment at the Jefferson National Laboratory, is evaluated in a hadronic model that includes couplings of theta(+) to both KN...

  8. Flutter-mills: from destructive phenomenon to the story of success

    E-Print Network [OSTI]

    Â?umer, Slobodan

    energy of wind, such a power plant hasn't been built yet. A clas, hydro power plants are important producers of electrical power and solar power plants are getting more

  9. 232 2005 IEEE International Solid-State Circuits Conference 0-7803-8904-2/05/$20.00 2005 IEEE. ISSCC 2005 / SESSION 12 / OPTICAL COMMUNICATIONS / 12.7

    E-Print Network [OSTI]

    Perrott, Michael

    droop problems. Therefore, the clas- sical use of CMOS source followers as PDs presents an unaccept- able tradeoff between settling time and droop. To dramatically improve the tradeoff between settling time and droop,

  10. Comment on the narrow structure reported by Amaryan et al

    E-Print Network [OSTI]

    M. Anghinolfi; J. Ball; N. A. Baltzell; M. Battaglieri; I. Bedlinskiy; M. Bellis; A. S. Biselli; C. Bookwalter; S. Boiarinov; P. Bosted; V. D. Burkert; D. S. Carman; A. Celentano; S. Chandavar; P. L. Cole; V. Crede; R. De Vita; E. De Sanctis; B. Dey; R. Dickson; D. Doughty; M. Dugger; R. Dupre; H. Egiyan; A. El Alaoui; L. El Fassi; L. Elouadrhiri; P. Eugenio; G. Fedotov; M. Y. Gabrielyan; M. Garcon; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; E. Golovatch; M. Guidal; L. Guo; K. Hafidi; H. Hakobyan; D. Heddle; K. Hicks; M. Holtrop; D. G. Ireland; B. S. Ishkhanov; E. L. Isupov; H. S. Jo; K. Joo; P. Khetarpal; A. Kim; W. Kim; V. Kubarovsky; S. V. Kuleshov; H. Y. Lu; L. J. D. MacGregor; N. Markov; M. E. McCracken; B. McKinnon; M. D. Mestayer; C. A. Meyer; M. Mirazita; V. Mokeev; K. Moriya; B. Morrison; A. Ni; S. Niccolai; G. Niculescu; I. Niculescu; M. Osipenko; A. I Ostrovidov; K. Park; S. Park; S. Anefalos Pereira; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; G. Ricco; M. Ripani; B. G. Ritchie; P. Rossi; D. Schott; R. A. Schumacher; E. Seder; Y. G. Sharabian; E. S. Smith; D. I Sober; S. S. Stepanyan; P. Stoler; W. Tang; M. Ungaro; B. Vernarsky; M. F. Vineyard; D. P. Weygand; M. H. Wood; N. Zachariou; B. Zhao

    2012-04-05T23:59:59.000Z

    The CLAS Collaboration provides a comment on the physics interpretation of the results presented in a paper published by M. Amaryan et al. regarding the possible observation of a narrow structure in the mass spectrum of a photoproduction experiment.

  11. Jefferson Lab Weekly Briefs March 25, 2015 | Jefferson Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    was planned for the months of March and April. Physics Jefferson Lab Published Journal Articles March 16-20 S. Pisano et al. (CLAS Collaboration). "Single and double spin...

  12. Photo-Production of Proton Antiproton Pairs

    SciTech Connect (OSTI)

    Paul Eugenio; Burnham Stokes

    2007-02-01T23:59:59.000Z

    Results are reported on the reaction gammap --> ppp-bar . A high statistic data set was obtained at the Thomas Jefferson National Accelerator Facility utilizing the CLAS detector and a tagged photon beam of 4.8 to 5.2 GeV incident on a liquid hydrogen target. The focus of this study was to search for possible intermediate resonances which decay to proton-antiproton. Both final state protons were detected in the CLAS apparatus whereas the antiproton was identified via missing mass. General features of the data are presented along with results on narrow and broad resonance studies.

  13. Photo-Production of Proton Antiproton Pairs

    SciTech Connect (OSTI)

    Eugenio, Paul; Stokes, Burnham [Department of Physics, Florida State University, Tallahassee, FL (United States)

    2007-02-27T23:59:59.000Z

    Results are reported on the reaction {gamma}p {yields} ppp-bar. A high statistic data set was obtained at the Thomas Jefferson National Accelerator Facility utilizing the CLAS detector and a tagged photon beam of 4.8 to 5.2 GeV incident on a liquid hydrogen target. The focus of this study was to search for possible intermediate resonances which decay to proton-antiproton. Both final state protons were detected in the CLAS apparatus whereas the antiproton was identified via missing mass. General features of the data are presented along with results on narrow and broad resonance studies.

  14. Branchwidth of Graphs B 101 boosting approach, applied to them, minimizes the out-

    E-Print Network [OSTI]

    Dimitrios, Thilikos

    permutation P. Surprisingly enough, other clas- sic Data Compression problems fall into this framework with other state-of-the-art compressors is presented in [4]. The experiments show that the boosting technique compressors. However, these positive features are achieved using more (time and space) resources. Data Sets

  15. Nucleon and Delta resonances in K Sigma(1385) photoproduction from nucleons

    E-Print Network [OSTI]

    Oh, Yongseok; Ko, Che Ming; Nakayama, K.

    2008-01-01T23:59:59.000Z

    . (CLAS Collaboration), Phys. Rev. C 71, 054609 (2005); 72, 039902(E) (2005). [26] M. Warns, W. Pfeil, and H. Rollnik, Phys. Lett. B258, 431 (1991). [27] G. Wagner, A. J. Buchmann, and A. Faessler, Phys. Rev. C 58, 1745 (1998); E. Kaxiras, E. J. Moniz...

  16. Checking NFA equivalence with bisimulations up to congruence

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Checking NFA equivalence with bisimulations up to congruence Filippo Bonchi CNRS, ENS Lyon--We introduce bisimulation up to congruence as a technique for proving language equivalence of non algorithm. I. INTRODUCTION Checking language equivalence of finite automata is a clas- sical problem

  17. Interior-point methods for linear programming: a guided tour

    E-Print Network [OSTI]

    Glineur, François

    linear programming1. The simplex algorithm, first developed by* * Dantzig in 1947, is a very.). However, an article by Karmarkar [Kar84] introduced in 1984 a new clas* *s of meth- ods: the so optimization problems. The purpose of this article is to give an overview of this rather new

  18. EFC Meeting Agenda Thursday, September 5, 1:00-2:00 PM

    E-Print Network [OSTI]

    Casavant, Tom

    , 2013 2. Announcements 3. Update on EFC election 4. Standing Committees: a. Updates on standingE General Education Courses (GECs): adopt languages for our GEC requirement that match CLAS's categories for underrepresented minorities. e. Graduate education and TA support. 6. New Business #12;

  19. LowEnergy Adder Design with a SinglePhase SourceCoupled Adiabatic Logic

    E-Print Network [OSTI]

    Papaefthymiou, Marios

    that uses a single­phase power­ clock. SCAL cascades comprise alternating PMOS and NMOS­type gates. LowLow­Energy Adder Design with a Single­Phase Source­Coupled Adiabatic Logic Suhwan Kim Marios C. In comparison with corresponding 8­bit CLAs in alternative logic styles that operate at minimum supply voltages

  20. A STUDENT NEWSLETTER SPRING 2007VISIONS of Latin America

    E-Print Network [OSTI]

    Machery, Edouard

    Infrastructure in South America: economic Development vs. Environment integration? 8 Un lustro sin Roberto Bolaño: The Articulation of Time, Space and Otherness 6 Amazonia and the Initiative for Integration of Regional at the University of Pittsburgh. The journal, sponsored by the Center for Latin American Studies (CLAS), is a venue

  1. Functional Data Analysis With Multi Layer Perceptrons

    E-Print Network [OSTI]

    Fleuret, François

    Analysis. We introduce a computation model for functional input data and we show that this model is a wellFunctional Data Analysis With Multi Layer Perceptrons Fabrice Rossi , Brieuc Conan-Guez and Fran as clas- sical multivariate data, because they are in general de- scribed by a finite set of input

  2. Functional Data Analysis With Multi Layer Perceptrons0

    E-Print Network [OSTI]

    Rossi, Fabrice

    Analysis. We introduce a computation model for functional input data and we show that this model is a wellFunctional Data Analysis With Multi Layer Perceptrons0 Fabrice Rossi1 , Brieuc Conan-Guez and Fran as clas- sical multivariate data, because they are in general de- scribed by a finite set of input

  3. Bag-of-Visual-Words Models for Adult Image Classification and Filtering Thomas Deselaers1

    E-Print Network [OSTI]

    Deselaers, Thomas

    types of images are allowed. In the literature, different porn image filtering tech- niques were features for porn image classification are pre- sented and used in a retrieval/nearest neighbour clas model to discriminate between different classes of content-type. 2 Porn Image Identification For porn

  4. Baryon Resonances in the Double Pion Channel at Jefferson Lab (CEBAF): Experimental and Physical Analysis Status and Perspectives

    E-Print Network [OSTI]

    Marco Ripani

    1999-02-18T23:59:59.000Z

    Decay of light quark excited baryons in the double pion channel is discussed, as a particular way of investigating poorly know baryon resonances and searching for "missing states" predicted by quark models. A possible approach to the data analysis is discussed and some preliminary data from the CLAS collaboration at Jefferson Laboratory are presented.

  5. Incremental training of Markov mixture models Andreas Kakoliris and Konstantinos Blekas

    E-Print Network [OSTI]

    Blekas, Konstantinos

    on an extension of the k-means algorithm. Then, by performing a two-stage scheme of the EM algorithm, the new been constructed through the use of an adaptation of the clas- sical k-means algorithm for treating of the proposed method, we have conducted experiments with several data sets and we make a performance comparison

  6. Navigation in Structured Multimedia Documents using Presentation Context

    E-Print Network [OSTI]

    Joseph Fourier Grenoble-I, Université

    Navigation in Structured Multimedia Documents using Presentation Context Loay Sabry­Ismail --- C in multimedia documents differs from the navigation in clas­ sical documents the fact that temporal information instants in the presentation of multimedia documents, and we describe how they can be used to navigate

  7. Sensors and Actuators A 171 (2011) 260265 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    Cao, Wenwu

    the Equivalent Circuit Method (ECM) [4], while Castillo [5] built a one- dimensional KLM model that takes considering the vibrator with flexural mode. Identical exper- imental conditions were used in the simulation to a high-intensity acoustic vibrator. The actuator for noncontact levitation consists of one clas- sical

  8. MPHYS Interim Report Alex Colvill

    E-Print Network [OSTI]

    Gilfoyle, Jerry

    ) subsystem of the upgraded Continuous Electron Beam Accelerator Facility Large Acceptance Spectrometer (CLAS called CEBAF, or Continuous Electron Beam Accelerator Facility, which supplies high quality, optionally owned facility, the centerpiece of which is a 7/8 of a mile long racetrack-shaped electron accelerator

  9. Journal Few-Body System manuscript No. (will be inserted by the editor)

    E-Print Network [OSTI]

    Gilfoyle, Jerry

    Electron Beam Accelerator Facility (CEBAF) made of 338 accelerating cavities which produce electrons Accelerator Facility (JLab) has a strong program in this area to support the JLab mission. In particular, we the CLAS detector. 2 Experimental Facilities The main scientific instrument at JLab is the Continuous

  10. Precise measurement of the neutron magnetic form factor GMn [G superscript n subscript M] in the Few-GeV2 [V superscript 2] region

    E-Print Network [OSTI]

    Rowntree, D.

    The neutron elastic magnetic form factor was extracted from quasielastic electron scattering on deuterium over the range Q2=1.0–4.8 [Q superscript 2 = 1.0-4.8] ??GeV2 [Ge V superscript 2] with the CLAS detector at Jefferson ...

  11. Classification and Utilization of Abstractions for Optimization

    E-Print Network [OSTI]

    Yi, Qing

    Classification and Utilization of Abstractions for Optimization Dan Quinlan1 , Markus Schordan2.sabjornsen@fys.uio.no Abstract. We define a novel approach to optimize the use of libraries within applications. We propose that library-defined abstractions be clas- sified to support their automated optimization and by leveraging

  12. APPLICATION OF THE FUZZY MIN-MAX NEURAL NETWORK CLASSIFIER

    E-Print Network [OSTI]

    Blekas, Konstantinos

    . The fuzzy min-max classi cation network constitutes a promisimg pattern recognition approach that is based. Experimental results us- ing the modi ed model on a di cult pattern recognition prob- lem establishes of the fuzzy min-max clas- si cation neural network on a pattern recognition problem that involves both

  13. August October 2012 In this Issue

    E-Print Network [OSTI]

    Watson, Craig A.

    and clas- sical studies, and including military tac- tics, to teach such branches of learning as are related to agriculture and mechan- ical arts... in order to promote the liberal and practical education is incompat- ible with Extension. Agents educate, and do not conduct research. Hence, agents should

  14. The EMC Effect in Spin Structure Functions A 12 GeV letter of intent to Jefferson Lab PAC 35

    E-Print Network [OSTI]

    Gilfoyle, Jerry

    The EMC Effect in Spin Structure Functions A 12 GeV letter of intent to Jefferson Lab PAC 35-dependent EMC effect uti- lizing CLAS12 in Hall B. We will polarize 7 Li, in which a highly polarized proton|7Li 1 in a range of 2 EMC effect emphasizes

  15. Joint porosity depth trend estimation and lithology/fluid classification by Bayesian inversion Kjartan Rimstad and Henning Omre

    E-Print Network [OSTI]

    Eidsvik, Jo

    ,0 Sand,Shale,Sand,kc Sand,zc Sand] and the prior model of is p(). We assume that seismic AVO data. The ultimate goal of this study is to clas- sify lithology/fluid from sesimic AVO data using our stochastic Consider a geological model of a reservoir in one dimension, and the four classes oil-, gas- and brine

  16. Helicity Asymmetry Measurement for pi^0 Photoproduction with FROST

    SciTech Connect (OSTI)

    Iwamoto, Hideko [George Washington U.

    2011-08-01T23:59:59.000Z

    This thesis reports on the first helicity asymmetry measurement for single neutral pion photoproduction using the CLAS detector in Hall B at the Thomas Jefferson National Accelerator Facility (JLab). This measurement used longitudinally polarized protons and circularly polarized photons at energies between 350 MeV and 2400 MeV. The experimental results are compared to three available model calculations.

  17. Branching Ratio of the Electromagnetic Decay of the ?+(1385)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Keller, D; Adhikari, K P; Adikaram, D; Amaryan, M J; Anghinolfi, M; Baghdasaryan, H; Ball, J; Battaglieri, M; Bedlinskiy, I; Biselli, A S; Bookwalter, C; Boiarinov, S; Branford, D; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Cole, P L; Contalbrigo, M; Crede, V; D' Angelo, A; Daniel, A; Dashyan, N; De Vita, R; De Sanctis, E; Djalali, C; Doughty, D; Dupre, R; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Gabrielyan, M Y; Gevorgyan, N; Gilfoyle, G P; Giovanetti, K L; Gohn, W; Golovatch, E; Gothe, R W; Graham, L; Griffioen, K A; Guidal, M; Guler, N; Guo, L; Hafidi, K; Hakobyan, H; Holtrop, M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jo, H S; Joo, K; Khandaker, M; Khertarpal, P; Kim, A; Kim, W; Klein, F J; Kubarovsky, A; Kubarovsky, V; Kuleshov, S V; Lu, H Y; MacGregor, I.J. D; Mao, Y; Markov, N; Mayer, M; McKinnon, B; Meyer, C A; Mirazita, M; Mokeev, V; Moutarde, H; Munevar, E; Nadel-Turonski, P; Nasseripour, R; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Paolone, M; Pappalardo, L; Paremuzyan, R; Anefalos Pereira, S; Pisano, S; Pogorelko, O; Pozdniakov, S; Procureur, S; Prok, Y; Protopopescu, D; Raue, B A; Ricco, G; Rimal, D; Ripani, M; Ritchie, B G; Rosner, G; Rossi, P; Sabatie, F; Saini, M S; Salgado, C; Schott, D; Schumacher, R A; Seraydaryan, H; Sharabian, Y G; Smith, E S; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Taiuti, M; Tang, W; Taylor, C E; Tkachenko, S; Vernarsky, B; Vineyard, M F; Vlassov, A V; Voskanyan, H; Voutier, E; Wood, M H; Zachariou, N; Zana, L; Zhao, B

    2012-03-23T23:59:59.000Z

    The CLAS detector was used to obtain the first ever measurement of the electromagnetic decay of the ?*+(1385) from the reaction ?p ? K0 ?*+(1385). A real photon beam with a maximum energy of 3.8 GeV was incident on a liquid-hydrogen target, resulting in the photoproduction of the kaon and ?* hyperon. Kinematic fitting was used to separate the reaction channel from the background processes. The fitting algorithm exploited a new method to kinematically fit neutrons in the CLAS detector, leading to the partial width measurement of 250.0 ± 56.9(stat)-41.2+34.3(sys) keV. A U-spin symmetry test using the SU(3) flavor-multiplet representation yields predictions for the ?*+(1385) ? ?+? and ?*0(1385) ? ?? partial widths that agree with the experimental measurements.

  18. Progress on Neutron-Target Multipoles above 1 GeV

    SciTech Connect (OSTI)

    Strakovsky, I I; Gao, H; Briscoe, W J; Dutta, D; Kudryavtsev, A E; Mirazite, M; Paris, M; Rossi, P; Stepanyan, S; Tarasov, V E

    2012-12-01T23:59:59.000Z

    We report a new extraction of nucleon resonance couplings using ?{sup ?} photo-production cross sections on the neutron. The world database for the process ?n ? ?{sup ?}p above 1 GeV has quadrupled with the addition of new differential cross sections from the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab in Hall B. Differential cross sections from CLAS have been improved with a new final-state interaction determination using a diagrammatic technique taking into account the SAID phenomenological NN and ?N final-state interaction amplitudes. Resonance couplings have been extracted and compared to previous determinations. With the addition of these new cross sections, significant changes are seen in the high-energy behavior of the SAID cross sections and amplitudes.

  19. Branching Ratio of the Electromagnetic Decay of the ?+(1385)

    SciTech Connect (OSTI)

    Keller, D; Adhikari, K P; Adikaram, D; Amaryan, M J; Anghinolfi, M; Baghdasaryan, H; Ball, J; Battaglieri, M; Bedlinskiy, I; Biselli, A S; Bookwalter, C; Boiarinov, S; Branford, D; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Cole, P L; Contalbrigo, M; Crede, V; D& #x27; Angelo, A; Daniel, A; Dashyan, N; De Vita, R; De Sanctis, E; Djalali, C; Doughty, D; Dupre, R; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Gabrielyan, M Y; Gevorgyan, N; Gilfoyle, G P; Giovanetti, K L; Gohn, W; Golovatch, E; Gothe, R W; Graham, L; Griffioen, K A; Guidal, M; Guler, N; Guo, L; Hafidi, K; Hakobyan, H; Holtrop, M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jo, H S; Joo, K; Khandaker, M; Khertarpal, P; Kim, A; Kim, W; Klein, F J; Kubarovsky, A; Kubarovsky, V; Kuleshov, S V; Lu, H Y; MacGregor, I.J. D; Mao, Y; Markov, N; Mayer, M; McKinnon, B; Meyer, C A; Mirazita, M; Mokeev, V; Moutarde, H; Munevar, E; Nadel-Turonski, P; Nasseripour, R; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Paolone, M; Pappalardo, L; Paremuzyan, R; Anefalos Pereira, S; Pisano, S; Pogorelko, O; Pozdniakov, S; Procureur, S; Prok, Y; Protopopescu, D; Raue, B A; Ricco, G; Rimal, D; Ripani, M; Ritchie, B G; Rosner, G; Rossi, P; Sabatie, F; Saini, M S; Salgado, C; Schott, D; Schumacher, R A; Seraydaryan, H; Sharabian, Y G; Smith, E S; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Taiuti, M; Tang, W; Taylor, C E; Tkachenko, S; Vernarsky, B; Vineyard, M F; Vlassov, A V; Voskanyan, H; Voutier, E; Wood, M H; Zachariou, N; Zana, L; Zhao, B

    2012-03-23T23:59:59.000Z

    The CLAS detector was used to obtain the first ever measurement of the electromagnetic decay of the ?*+(1385) from the reaction ?p ? K0 ?*+(1385). A real photon beam with a maximum energy of 3.8 GeV was incident on a liquid-hydrogen target, resulting in the photoproduction of the kaon and ?* hyperon. Kinematic fitting was used to separate the reaction channel from the background processes. The fitting algorithm exploited a new method to kinematically fit neutrons in the CLAS detector, leading to the partial width measurement of 250.0 ± 56.9(stat)-41.2+34.3(sys) keV. A U-spin symmetry test using the SU(3) flavor-multiplet representation yields predictions for the ?*+(1385) ? ?+? and ?*0(1385) ? ?? partial widths that agree with the experimental measurements.

  20. Branching Ratio of the Electromagnetic Decay of the ?+(1385)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Keller, D; Adhikari, K P; Adikaram, D; Amaryan, M J; Anghinolfi, M; Baghdasaryan, H; Ball, J; Battaglieri, M; Bedlinskiy, I; Biselli, A S; et al

    2012-03-23T23:59:59.000Z

    The CLAS detector was used to obtain the first ever measurement of the electromagnetic decay of the ?*+(1385) from the reaction ?p ? K0 ?*+(1385). A real photon beam with a maximum energy of 3.8 GeV was incident on a liquid-hydrogen target, resulting in the photoproduction of the kaon and ?* hyperon. Kinematic fitting was used to separate the reaction channel from the background processes. The fitting algorithm exploited a new method to kinematically fit neutrons in the CLAS detector, leading to the partial width measurement of 250.0 ± 56.9(stat)-41.2+34.3(sys) keV. A U-spin symmetry test using the SU(3) flavor-multiplet representationmore »yields predictions for the ?*+(1385) ? ?+? and ?*0(1385) ? ?? partial widths that agree with the experimental measurements.« less

  1. Measurements Of Spin Observables In Pseudoscalar-Meson Photo-Production Using Polarized Neutrons In Solid HD

    SciTech Connect (OSTI)

    Kageya, Tsuneo

    2014-01-01T23:59:59.000Z

    Psuedo-scalar meson photo production measurements have been carried out with longitudinally-polarized neutrons using the circularly and linearly polarized photon beams and the CLAS at Thomas Jefferson National Accelerator Facility (Jlab). The experiment aims to obtain a complete set of spin observables on an efficient neutron target. Preliminary E asymmetries for the exclusive reaction, gamma + n(p)--> pi- + p(p), selecting quasi free neutron kinematics are discussed.

  2. Extracting meson-baryon contributions to the electroexcitation of the N(1675)52- nucleon resonance

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aznauryan, Inna G.; Burkert, Volker D.

    2015-07-01T23:59:59.000Z

    We report on the determination of the electrocouplings for the transition from the proton to the $N(1675){\\frac{5}{2}}^-$ resonance state using recent differential cross section data on $e p \\rightarrow e\\pi^+ n$ by the CLAS collaboration at $1.8 \\le Q^2 more »contributions at $Q^2 \\geq 1.8 $GeV$^2$ from the dynamical coupled-channel model.« less

  3. Preliminary results of t and f asymmetries for {eta} photoproduction from the proton

    SciTech Connect (OSTI)

    Tucker, Ross J. [Arizona State Univ., Tempe, AZ (United States); Ritchie, Barry G. [Arizona State Univ., Tempe, AZ (United States); Dugger, Michael R. [Arizona State Univ., Tempe, AZ (United States)

    2014-01-01T23:59:59.000Z

    We present preliminary data for the T and F asymmetries in {eta} photoproduction from the proton, along with comparisons to theoretical predictions. The data used in the present analysis were taken using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab, a cryogenic target which utilized transversely polarized protons in a butanol target, and incident tagged photons with energy between 0.62 and 2.93 GeV.

  4. Polarization Measurements in Photoproduction with CEBAF Large Acceptance Spectrometer

    SciTech Connect (OSTI)

    E. Pasyuk

    2010-05-01T23:59:59.000Z

    A significant part of the experimental program in Hall-B of the Jefferson Lab is dedicated to the studies of the structure of baryons. CEBAF Large Acceptance Spectrometer (CLAS), availability of circularly and linearly polarized photon beams and recent addition of polarized targets provides remarkable opportunity for single, double and in some cases triple polarization measurements in photoproduction. An overview of the experiments will be presented.

  5. A synoptic-scale evaluation of cyclogenesis using satellite radiation data

    E-Print Network [OSTI]

    Mills, Jerry Ray

    1976-01-01T23:59:59.000Z

    of heat and water vapor are released into the free atmosphere. Con- vective clouds associated with these cyclonic disturbances act as a primary energy transport mechanism and play a large role in the eventu- al transformation of a deep atmospheric layer.... (1962) and Oliver et al. (1964), among others. Although the essential features and processes of the Bjerknes clas- sical cyclone model have not changed through the years, some revisions, notably to cloud distributions, were necessary due to the study...

  6. Polarization Observables From The Photoproduction Of Omega-Mesons Using Linearly Polarized Photons

    SciTech Connect (OSTI)

    Martinez, Danny [Idaho State University, Pocatello, ID (United States); Cole, Philip L. [Idaho State University, Pocatello, ID (United States)

    2014-01-01T23:59:59.000Z

    We report on the extraction of Polarization Observables Spin Density Matrix Elements (SDMEs), and Beam Asymmetry Sigma for omega meson photoproduction using a beam of linearly polarized photons in the photon energy region of Egamma = 1.3 to 1.7 GeV, by means of the angular distributions of the daughter pions from omega decay. These preliminary results are from the g8b dataset, which were collected with the CLAS detector in Hall B of Jefferson Lab.

  7. The BoNuS Experiment At Jefferson Lab

    SciTech Connect (OSTI)

    Bueltmann, Stephen [Old Dominion University, Physics Department, Norfolk, VA 23529 (United States)

    2005-02-10T23:59:59.000Z

    The BoNuS experiment at Jefferson Lab's Hall B is going to measure the structure of the quasi-free neutron via electron scattering off a deuteron target and detection of the slowly recoiling spectator proton at very backward angles. To detect the low momentum backward recoiling protons, the CLAS detector will be augmented with a novel radial time projection chamber featuring gas electron multipliers. Data taking is anticipated for 2005 or 2006.

  8. Neutron Structure Function from BoNuS

    SciTech Connect (OSTI)

    Bueltmann, Stephen [Physics Department, Old Dominion University, Norfolk, VA 23529 (United States)

    2011-09-21T23:59:59.000Z

    The BoNuS experiment at Jefferson Lab's Hall B measured the structure of the quasi-free neutron via electron scattering off a deuteron target and detection of the slowly recoiling spectator protonat very backward angles. The very low momentum backward recoiling protons were detected by a novel radial time projection chamber featuring gas electron multipliers, augmenting the CLAS detector. Data were taken successfully in the Fall of 2005.

  9. The BoNuS Experiment At Jefferson Lab

    SciTech Connect (OSTI)

    Stephen Baltmann

    2005-02-01T23:59:59.000Z

    The BoNuS experiment at Jefferson Lab's Hall B is going to measure the structure of the quasi-free neutron via electron scattering off a deuteron target and detection of the slowly recoiling spectator proton at very backward angles. To detect the low momentum backward recoiling protons, the CLAS detector will be augmented with a novel radial time projection chamber featuring gas electron multipliers. Data taking is anticipated for 2005 or 2006.

  10. Diversity Outlook, November 2012

    E-Print Network [OSTI]

    2012-11-01T23:59:59.000Z

    decades. I extend my sincere thanks to Sr. Vice Provost Sara Rosen and CLAS Dean Danny Anderson for their support and guidance in making this recognition possible. Full details are on page 2; I hope the entire campus community will attend to show our.... The committee responsible for the video: Frank Barthell, producer, and Corey Stone, Office of Public Affairs; Allen Humphrey, assistant director, Human Resources; Patti Wakolee, senior academic advisor; Nicole Hodges Persley, theatre faculty; Mary Ellen...

  11. Nucleon Structure Studies with Electromagnetic Probes

    SciTech Connect (OSTI)

    Vineyard, Michael F.

    2011-03-31T23:59:59.000Z

    Summarized in this report is the progress achieved during the period from March 1, 2008 to June 14, 2009 under contract number DE-FG02-03ER41252. This is the final technical report under this contract. The experimental work described here is part of the electromagnetic nuclear physics program of the CEBAF Large Acceptance Spectrometer (CLAS) Collaboration at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) that published 17 journal articles during the period of this report. One of these journal articles reported on the results of precise measurements of the neutron magnetic form factor. I was a spokesperson on this experiment and the publication of these results is the culmination of years of effort by a small subset of the CLAS Collaboration. As usual, undergraduate students were involved in all aspects of this work. Three Union College students participated in this program during the window of this report and one presented a paper on his work at the 2009 National Conference on Undergraduate Research (NCUR22). In this report, I discuss recent progress on the measurements of the neutron magnetic form factor and describe my service work for the CLAS Collaboration.

  12. Strangeness Suppression of qq? Creation Observed in Exclusive Reactions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mestayer, Mac [JLAB; Park, Kijun; Adhikari, Krishna; Aghasyan, Mher; Anefalos Pereira, Sergio; Ball, Jacques; Battaglieri, Marco; Batourine, V; Bedlinskiy, Ivan; Biselli, Angela; Boyarinov, Sergey; Briscoe, William; Brooks, William; Burkert, Volker; Carman, Daniel; Celentano, Andrea; Chandavar, Shloka; Charles, Gabriel; Colaneri, Luca; Cole, Philip; Contalbrigo, Marco; Cortes, Olga; Crede, Volker; D'Angelo, Annalisa; Dashyan, Natalya; De Vita, Raffaella; Deur, Alexandre; Djalali, Chaden; Doughty, David; Dupre, Raphael; El Alaoui, Ahmed; El Fassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Fleming, Jamie; Forest, Tony; Garillon, Brice; Garcon, Michel; Ghandilyan, Yeranuhi; Gilfoyle, Gerard; Giovanetti, Kevin; Girod-Gard, Francois-Xavier; Goetz, John; Golovach, Evgeny; Gothe, Ralf; Griffioen, Keith; Guegan, Baptiste; Guidal, Michel; Hakobyan, Hayk; Hanretty, Charles; Hattawy, Mohammad; Holtrop, Maurik; Hughes, Simon; Hyde, Charles; Ilieva, Yordanka; Ireland, David; Jiang, Hao; Jo, Hyon-Suk; Joo, Kyungseon; Keller, Dustin; Khandaker, Mahbubul; Kim, Andrey; Kim, Wooyoung; Koirala, Suman; Kubarovsky, Valery; Kuleshov, Sergey; Lenisa, Paolo; Levine, William; Livingston, Ken; Lu, Haiyun; MacGregor, Ian; Mayer, Michael; McKinnon, Bryan; Meyer, Curtis; Mirazita, Marco; Mokeev, Viktor; Montgomery, Rachel; Moody, Cristina; Moutarde, Herve; Movsisyan, Aram; Munoz Camacho, Carlos; Nadel-Turonski, Pawel; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria; Osipenko, Mikhail; Ostrovidov, Alexander; Pappalardo, Luciano; Paremuzyan, Rafayel; Peng, Peng; Phelps, William; Pisano, Silvia; Pogorelko, Oleg; Pozdniakov, Serguei; Price, John; Protopopescu, Dan; Puckett, Andrew; Raue, Brian; Rimal, Dipak; Ripani, Marco; Rizzo, Alessandro; Rosner, Guenther; Roy, Priyashree; Sabatie, Franck; Saini, Mukesh; Schott, Diane; Schumacher, Reinhard; Simonyan, Ani; Sokhan, Daria; Strauch, Steffen; Sytnik, Valeriy; Tang, Wei; Tian, Ye; Ungaro, Maurizio; Vernarsky, Brian; Vlasov, Alexander; Voskanyan, Hakob; Voutier, Eric; Walford, Natalie; Watts, Daniel; Wei, Xiangdong; Weinstein, Lawrence; Wood, Michael; Zachariou, Nicholas; Zhang, Jixie; Zhao, Zhiwen; Zonta, Irene

    2014-10-01T23:59:59.000Z

    We measured the ratios of electroproduction cross sections from a proton target for three exclusive meson-baryon final states: ?K+, p?0, and n?+, with the CLAS detector at Jefferson Lab. Using a simple model of quark hadronization, we extract qq¯ creation probabilities for the first time in exclusive two-body production, in which only a single qq¯ pair is created. We observe a sizable suppression of strange quark-antiquark pairs compared to nonstrange pairs, similar to that seen in high-energy production.

  13. Multipole approach for photo- and electroproduction of kaon

    E-Print Network [OSTI]

    T. Mart; A. Sulaksono

    2007-01-03T23:59:59.000Z

    We have analyzed the experimental data on K+Lambda photoproduction by using a multipole approach. In this analysis we use the background amplitudes constructed from appropriate Feynman diagrams in a gauge-invariant and crossing-symmetric fashion. Results of our analysis reveal the problem of mutual consistency between the new SAPHIR and CLAS data. We found that the problem could lead to different conclusions on ``missing resonances''. We have also extended our analysis to the finite Q^2 region and compared the result with the corresponding electroproduction data.

  14. Setting in the Modern Short Story

    E-Print Network [OSTI]

    Hodgson, Elizabeth

    1913-06-05T23:59:59.000Z

    . Thompson , D~'I G. The Ph1losophY ot Fiation. Lo on" l8~. Wh1tcomb , S. L. st of th Novei . Boston, 1 ·5. II. II. L short-starl: AI 'bright, ].'velyn 1La.Y . Tltle Short story. N. Y., 1 O? Barrett , Chas. P. Short story Writing . N. ., 188. Canby... . III. Matthews, Brander . The Short - st ory. N. :x.., 1 07 . Patton, Wm. International Short-stori e , 2 vols • • Y., 1 ~lO. Short-stor y Classios--Amerlcan , 5 vols ., N. Y. t 1':;)05 . , , Short-story Clas8~cs--Foreign , 5 vole . N. ¥ . ! II...

  15. A review of "The Writings of an English Sappho" edited by Patricia Phillippy, translated by Jaime Goodrich

    E-Print Network [OSTI]

    Raber, Karen

    2012-01-01T23:59:59.000Z

    one of the #23; ve learned daughters of Sir Anthony Cooke in 1540; that the sisters were given a thorough clas- sical education is evidenced by Elizabeth?s numerous poems, epitaphs and inscriptions in Latin and Greek, ably translated for the volume... created a monument to her father and mother that ?makes it clear that Anthony Cooke?s intellectual legacy was car- ried on not by his sons, but by his daughters? (160), yet a#27; rms the daughters as following their mother?s pattern by representing...

  16. Studies of spin-orbit correlations at JLAB

    SciTech Connect (OSTI)

    Mher Aghasyan, Harut Avakian

    2011-05-01T23:59:59.000Z

    Studies of single spin asymmetries for pion electroproduction in semi-inclusive deep-inelastic scattering are presented using the polarized \\sim6 GeV electrons from at the Thomas Jefferson National Accelerator Facility (JLab) and the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) with the Inner Calorimeter. The cross section versus the azimuthal angle {\\phi}_h of the produced neutral pion has a substantial sin {\\phi}_h amplitude. The dependence of this amplitude on Bjorken x_B and on the pion transverse momentum is extracted and compared with published data.

  17. Light Vector Meson Photoproduction off of H at Jefferson Lab and rho-omega Interference in the Leptonic Decay Channel

    SciTech Connect (OSTI)

    Chaden Djalali

    2011-12-01T23:59:59.000Z

    Recent studies of light vector meson production in heavy nuclear targets has generated interest in {rho}-{omega} interference in the leptonic e{sup +}e{sup -} decay channel. An experimental study of the elementary process provides valuable input for theoretical models and calculations. In experiment E04-005 (g12), high statistics photoproduction data has been taken in Jefferson Lab's Hall B with the Cebaf Large Acceptance Spectrometer (CLAS). The invariant mass spectrum is fitted with two interfering relativistic Breit-Wigner functions to determine the interference phase. Preliminary analysis indicate a measurable {rho}-{omega} interference.

  18. The Forward Tagger facility for low Q{sup 2} experiments at Jefferson Laboratory

    SciTech Connect (OSTI)

    Celentano, Andrea [INFN-GENOVA

    2014-06-01T23:59:59.000Z

    Low Q{sup 2} electron scattering is an efficient and competitive experimental technique to provide intense, quasi-real photon beams, with a high degree of linear polarization. Such a technique will be employed in Hall B at Jefferson Laboratory by having the primary 11?GeV electron beam from the CEBAF accelerator impinging on a liquid hydrogen target. Low-angle scattered electrons will be detected with the new Forward Tagger facility, while the final state hadrons will be measured with the CLAS12 spectrometer. The unique combination of the two detectors will permit to carry out a broad physics program, and to explore new possibilities for high quality physics.

  19. Differential cross sections for the reactions gamma p-> p eta and gamma p -> p eta-prime

    E-Print Network [OSTI]

    M. Williams; Z. Krahn; D. Applegate; M. Bellis; C. A. Meyer; for the CLAS Collaboration

    2009-10-19T23:59:59.000Z

    High-statistics differential cross sections for the reactions gamma p -> p eta and gamma p -> p eta-prime have been measured using the CLAS at Jefferson Lab for center-of-mass energies from near threshold up to 2.84 GeV. The eta-prime results are the most precise to date and provide the largest energy and angular coverage. The eta measurements extend the energy range of the world's large-angle results by approximately 300 MeV. These new data, in particular the eta-prime measurements, are likely to help constrain the analyses being performed to search for new baryon resonance states.

  20. Precise Measurements of Beam Spin Asymmetries in Semi-Inclusive ?0 production

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Holtrop, M; Hyde, C E; Ireland, D G; Isupov, E L; Jawalkar, S S; Jenkins, D; Jo, H S; Joo, K; Keller, D; Khandaker, M; Khetarpal, P; Kim, A; Kimy, W; Klein, A; Klein, F J; Kubarovsky, V; Kuhn, S E; Kuleshov, S V; Kuznetsov, V; Kvaltine, N D; Livingston, K; Lu, H Y; MacGregor, I.J. D.; Markov, N; Mayer, M; McAndrew, J; McKinnon, B; Meyer, C A; Micherdzinska, A.M.; Mokeev, V; Moreno, B; Moutarde, H; Munevar, E; Nadel-Turonski, P; Ni, A; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Paolone, M; Pappalardo, L; Paremuzyan, R; Park, K; Park, S; Pasyuk, E; Anefalos Pereira, S; Phelps, E; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Raue, B A; Ricco, G; Rimal, D; Ripani, M; Rosner, G; Sabatio, F; Saini, M S; Salgado, C; Schott, D; Schumacher, R A; Seder, E; Seraydaryan, H; Sharabian, Y G; Smith, G D; Sober, D I; Stepanyan, S S; Stepanyan, S; Stoler, P; Strakovsky, I; Strauch, S; Taiuti, M; Tang, W; Taylor, C E; Tkachenko, S; Ungaro, M; Voskanyan, H; Voutier, E; Watts, D; Weinstein, L B; Weygand, D P; Wood, M H; Zana, L; Zhang, J; Zhao, B; Zhao, Z W

    2011-10-25T23:59:59.000Z

    We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. A substantial sin ?h amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle ?h of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations.

  1. Studies of spin-orbit correlations at JLAB

    E-Print Network [OSTI]

    Aghasyan, Mher

    2011-01-01T23:59:59.000Z

    Studies of single spin asymmetries for pion electroproduction in semi-inclusive deep-inelastic scattering are presented using the polarized \\sim6 GeV electrons from at the Thomas Jefferson National Accelerator Facility (JLab) and the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) with the Inner Calorimeter. The cross section versus the azimuthal angle {\\phi}_h of the produced neutral pion has a substantial sin {\\phi}_h amplitude. The dependence of this amplitude on Bjorken x_B and on the pion transverse momentum is extracted and compared with published data.

  2. Studies of spin-orbit correlations at JLAB

    E-Print Network [OSTI]

    Mher Aghasyan; Harut Avakian

    2011-03-16T23:59:59.000Z

    Studies of single spin asymmetries for pion electroproduction in semi-inclusive deep-inelastic scattering are presented using the polarized \\sim6 GeV electrons from at the Thomas Jefferson National Accelerator Facility (JLab) and the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) with the Inner Calorimeter. The cross section versus the azimuthal angle {\\phi}_h of the produced neutral pion has a substantial sin {\\phi}_h amplitude. The dependence of this amplitude on Bjorken x_B and on the pion transverse momentum is extracted and compared with published data.

  3. Strangeness Suppression in q-qbar Creation Observed in Exclusive Reactions

    E-Print Network [OSTI]

    K. Park; M. D. Mestayer; the CLAS collaboration

    2014-12-09T23:59:59.000Z

    We measured the ratios of electroproduction cross-sections from a proton target for three exclusive meson-baryon final states: $\\Lambda K^+$, $p\\pi^0$, and $n\\pi^+$, with the CLAS detector at Jefferson Lab. Using a simple model of quark hadronization we extract q-qbar creation probabilities for the first time in exclusive two-body production, in which only a single q-qbar pair is created. We observe a sizable suppression of strange quark-antiquark pairs compared to non-strange pairs, similar to that seen in high-energy production.

  4. Upper limits for the photoproduction cross section for the ???(1860) pentaquark state off the deuteron

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Egiyan, H.; Langheinrich, J.; Gothe, R. W.; Graham, L.; Holtrop, M.; Lu, H.; Mattione, P.; Mutchler, G.; Park, K.; Smith, E. S.; Stepanyan, S.; Zhao, Z. W.; Adhikari, K. P.; Aghasyan, M.; Anghinolfi, M.; Baghdasaryan, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Bedlinskiy, I.; Bennett, R. P.; Biselli, A. S.; Bookwalter, C.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Contalbrigo, M.; D’Angelo, A.; Daniel, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Dey, B.; Dickson, R.; Djalali, C.; Doughty, D.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fradi, A.; Gabrielyan, M. Y.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Griffioen, K. A.; Guidal, M.; Guler, N.; Guo, L.; Gyurjyan, V.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Heddle, D.; Hicks, K.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jo, H. S.; Joo, K.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Kubarovsky, V.; Kuleshov, S. V.; Livingston, K.; MacGregor, I. J. D.; Mao, Y.; Mayer, M.; McKinnon, B.; Mokeev, V.; Munevar, E.; Nadel-Turonski, P.; Ni, A.; Niculescu, G.; Ostrovidov, A. I.; Paolone, M.; Pappalardo, L.; Paremuzyan, R.; Park, S.; Pasyuk, E.; Anefalos Pereira, S.; Phelps, E.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Raue, B. A.; Ricco, G.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Stepanyan, S. S.; Strauch, S.; Taiuti, M.; Tang, W.; Taylor, C. E.; Tedeschi, D. J.; Ungaro, M.; Voutier, E.; Watts, D. P.; Weinstein, L. B.; Weygand, D. P.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhao, B.

    2012-01-01T23:59:59.000Z

    We searched for the ???(1860) pentaquark in the photoproduction process off the deuteron in the ????-decay channel using CLAS. The invariant-mass spectrum of the ???? system does not indicate any statistically significant enhancement near the reported mass M=1.860 GeV. The statistical analysis of the sideband-subtracted mass spectrum yields a 90%-confidence-level upper limit of 0.7 nb for the photoproduction cross section of ???(1860) with a consecutive decay into???? in the photon-energy range 4.5GeV?<5.5GeV.

  5. Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction ?p ? ?p

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dey, B. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Meyer, C. A. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Bellis, M. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Williams, M. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Adhikari, K. P. [Old Dominion Univ., Norfolk, VA (United States); Adikaram, D. [Old Dominion Univ., Norfolk, VA (United States); Aghasyan, M. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LFN); Amaryan, M. J. [Old Dominion Univ., Norfolk, VA (United States); Anderson, M. D. [Univ. of Glasgow, Scotland (United Kingdom); Anefalos Pereira, S. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LFN); Ball, J. [Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA), Saclay (France). Inst. de Physique Nuclaeaire; Baltzell, N. A. [Argonne National Lab. (ANL), Argonne, IL (United States); Battaglieri, M. [Istituto Nazionale di Fisica Nucleare (INFN), Genova (Italy); Bedlinskiy, I. [Inst. of Theoretical and Experimental Physics (ITEP), Moscow (Russian Federation); Biselli, A. S. [Fairfield Univ., CT (United States); Bono, J. [Florida International Univ., Miami, FL (United States); Boiarinov, S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Briscoe, W. J. [George Washington Univ., Washington, DC (United States); Brooks, W. K. [Univ. Tecnica Federico Santa Maria, Valparaiso (Chile); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Burkert, V. D. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Carman, D. S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Celentano, A. [Istituto Nazionale di Fisica Nucleare (INFN), Genova (Italy); Chandavar, S. [Ohio Univ., Athens, OH (United States); Colaneri, L. [National Inst. of Nuclear Physics (INFN), Rome (Italy); Cole, P. L. [Idaho State Univ., Pocatello, ID (United States); Contalbrigo, M. [National Inst. of Nuclear Physics (INFN), Ferrara (Italy); Cortes, O. [Idaho State Univ., Pocatello, ID (United States); Crede, V. [Florida State Univ., Tallahassee, FL (United States); D'Angelo, A. [National Inst. of Nuclear Physics (INFN), Rome (Italy); Univ. di Roma, Rome (Italy); Dashyan, N. [Yerevan Physics Inst. (YerPhI) (Armenia); De Vita, R. [Istituto Nazionale di Fisica Nucleare (INFN), Genova (Italy); De Sanctis, E. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LFN); Deur, A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Djalali, C. [Univ. of South Carolina, Columbia, SC (United States); Doughty, D. [Christopher Newport Univ., Newport News, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Dugger, M. [Arizona State Univ., Tempe, AZ (United States); Dupre, R. [Argonne National Lab. (ANL), Argonne, IL (United States); El Alaoui, A. [Argonne National Lab. (ANL), Argonne, IL (United States); El Fassi, L. [Argonne National Lab. (ANL), Argonne, IL (United States); Elouadrhiri, L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Fedotov, G. [Univ. of South Carolina, Columbia, SC (United States); Fegan, S. [Univ. of Glasgow, Scotland (United Kingdom); Fleming, J. A. [Univ. of Edinburgh, Scotland (United Kingdom); Garçon, M. [Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA), Saclay (France). Inst. de Physique Nuclaeaire; Gevorgyan, N. [Yerevan Physics Inst. (YerPhI) (Armenia); Ghandilyan, Y. [Yerevan Physics Inst. (YerPhI) (Armenia); Gilfoyle, G. P. [Univ. of Richmond, VA (United States); Giovanetti, K. L. [James Madison Univ., Harrisonburg, VA (Untied States); Girod, F. X. [Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA), Saclay (France). Inst. de Physique Nuclaeaire; Glazier, D. I. [Univ. of Edinburgh, Scotland (United Kingdom); Goetz, J. T. [Ohio Univ., Athens, OH (United States)

    2014-05-01T23:59:59.000Z

    High-statistics measurements of differential cross sections and spin density matrix elements for the reaction ? p ? ?p have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (?s) from 1.97 to 2.84 GeV, with an extensive coverage in the ? production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the ? natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged- (? ? K?K?) and neutral- (? ? K0SK0L) KK? decay modes of the ?. Further, for the charged mode, we differentiate between the cases where the final K? track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed ? mass resolution. Our final results are reported in 10- and mostly 30-MeV-wide ?s bins for the charged- and the neutral-mode, respectively. Possible effects from K??* channels with pKK? final-states are discussed. These present results constitute the most precise and extensive ? photoproduction measurements to date and in conjunction with the ? photoproduction results recently published by CLAS, will greatly improve our understanding of low energy vector meson photoproduction.

  6. Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction ? p ? ?p

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dey, Biplab [Carnegie Mellon Univ., Pittsburgh, PA (United States); Meyer, Curtis A. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Bellis, Matt [Carnegie Mellon Univ., Pittsburgh, PA (United States); Williams, M. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2014-05-01T23:59:59.000Z

    High-statistics measurements of differential cross sections and spin density matrix elements for the reaction ? p--> ?p have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (?s) from 1.97 to 2.84 GeV, with an extensive coverage in the ? production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the phi natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged- (?-->K+K- and neutral- (?-K0SK0L) KK? decay modes of the ?. Further, for the charged mode, we differentiate between the cases where the final K-track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed ? mass resolution. Our final results are reported in 10- and mostly 30-MeV-wide ?s bins for the charged- and the neutral-mode, respectively. Possible effects from K+?* channels with pKK? final-states are discussed. These present results constitute the most precise and extensive ? photoproduction measurements to date and in conjunction with the ? photoproduction results recently published by CLAS, will greatly improve our understanding of low energy vector meson photoproduction. ? p --> ?p

  7. Differential cross section of gamma n to K+ Sigma- on bound neutrons with incident photons from 1.1 to 3.6 GeV

    E-Print Network [OSTI]

    S. Anefalos Pereira; M. Mirazita; P. Rossi; E. De Sanctis; G. Niculescu; I. Niculescu; S. Stepanyan; for the CLAS Collaboration

    2010-02-03T23:59:59.000Z

    Differential cross sections of the reaction gamma d to K+ Sigma- (p) have been measured with the CLAS detector at Jefferson Lab using incident photons with energies between 1.1 and 3.6 GeV. This is the first complete set of strangeness photoproduction data on the neutron covering a broad angular range. At energies close to threshold and up to E_gamma ~ 1.8 GeV, the shape of the angular distribution is suggestive of the presence of s-channel production mechanisms. For E_gamma > 1.8 GeV, a clear forward peak appears and becomes more prominent as the photon energy increases, suggesting contributions from t-channel production mechanisms. These data can be used to constrain future analysis of this reaction.

  8. Determination of the Beam-Spin Asymmetry of Deuteron Photodisintegration in the Energy Region $E_?=1.1-2.3$ GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zachariou, Nicholas; et. al.,

    2015-05-01T23:59:59.000Z

    The beam-spin asymmetry, Sigma, for the reaction ?d-->pn has been measured using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility (JLab) for six photon-energy bins, between 1.1 and 2.3 GeV, and proton angles in the center-of-mass frame, thetac.m., between 25degrees and 160degrees. These are the first measurements of beam-spin asymmetries at thetac.m.=90degrees for photon-beam energies above 1.6 GeV, and the first measurements for angles other than thetac.m.=90degrees. The angular and energy dependence of Sigma is expected to aid in the development of QCD-based models to understand the mechanisms of deuteron photodisintegration in the transition regionmore »between hadronic and partonic degrees of freedom, where both effective field theories and perturbative QCD cannot make reliable predictions.« less

  9. Determination of the Beam-Spin Asymmetry of Deuteron Photodisintegration in the Energy Region $E_\\gamma=1.1-2.3$ GeV

    E-Print Network [OSTI]

    Zachariou, Nicholas; Ivanov, Nikolay Ya; Sargsian, Misak M; Avakian, Robert; Feldman, Gerald; Nadel-Turonski, Pawel; Adhikari, K P; Adikaram, D; Anderson, M D; Pereira, S Anefalos; Avakian, H; Badui, R A; Baltzell, N A; Battaglieri, M; Baturin, V; Bedlinskiy, I; Biselli, A S; Briscoe, W J; Brooks, W K; Burkert, V D; Cao, T; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Colaneri, L; Cole, P L; Compton, N; Contalbrigo, M; Cortes, O; Crede, V; D'Angelo, A; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dupre, R; Egiyan, H; Alaoui, A El; Fassi, L El; Elouadrhiri, L; Fedotov, G; Fegan, S; Filippi, A; Fleming, J A; Forest, T A; Fradi, A; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Glazier, D I; Golovatch, E; Gothe, R W; Griffioen, K A; Guidal, M; Hafidi, K; Hanretty, C; Harrison, N; Hattawy, M; Hicks, K; Ho, D; Holtrop, M; Hughes, S M; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jiang, H; Jo, H S; Joo, K; Keller, D; Khachatryan, G; Khandaker, M; Kim, A; Kim, W; Klein, F J; Kubarovsky, V; Lenisa, P; Livingston, K; Lu, H Y; MacGregor, I J D; Markov, N; Mattione, P T; McKinnon, B; Mineeva, T; Mirazita, M; Mokeeev, V I; Montgomery, R A; Moutarde, H; Camacho, C Munoz; Net, L A; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Phelps, W; Phillips, J J; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Puckett, A J R; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatié, F; Salgado, C; Schott, D; Schumacher, R A; Seder, E; Senderovich, I; Sharabian, Y G; Skorodumina, Iu; Smith, G D; Sober, D I; Sokhan, D; Sparveris, N; Stepanyan, S; Strauch, S; Sytnik, V; Taiuti, M; Tian, Ye; Ungaro, M; Voskanyan, H; Voutier, E; Walford, N K; Watts, D; Wei, X; Wood, M H; Zana, L; Zhang, J; Zhao, Z W; Zonta, I

    2015-01-01T23:59:59.000Z

    The beam-spin asymmetry, $\\Sigma$, for the reaction $\\gamma d\\rightarrow pn$ has been measured using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility (JLab) for six photon-energy bins between 1.1 and 2.3 GeV, and proton angles in the center-of-mass frame, $\\theta_{c.m.}$, between $25^\\circ$ and $160^\\circ$. These are the first measurements of beam-spin asymmetries at $\\theta_{c.m.}=90^\\circ$ for photon-beam energies above 1.6 GeV, and the first measurements for angles other than $\\theta_{c.m.}=90^\\circ$. The angular and energy dependence of $\\Sigma$ is expected to aid in the development of QCD-based models to understand the mechanisms of deuteron photodisintegration in the transition region between hadronic and partonic degrees of freedom, where both effective field theories and perturbative QCD cannot make reliable predictions.

  10. Radiative decays of the Sigma0(1385) and Lambda(1520) hyperons

    E-Print Network [OSTI]

    S. Taylor; G. S. Mutchler; for the CLAS collaboration

    2005-07-08T23:59:59.000Z

    The electromagnetic decays of the Sig0(1385) and Lambda(1520) hyperons were studied in photon-induced reactions gamma p -> K+ Lambda(1116)gamma in the CLAS detector at the Thomas Jefferson National Accelerator Facility. We report the first observation of the radiative decay of the Sig0(1385) and a measurement of the Lambda(1520) radiative decay width. For the Sig0(1385) -> Lambda(1116)gamma transition, we measured a partial width of 479+/-120(stat)+81-100(sys) keV, larger than all of the existing model predictions. For the Lambda(1520) -> Lambda(1116)gamma transition, we obtained a partial width of 167+/-43(stat)+26-12(sys) keV.

  11. Determination of the Beam-Spin Asymmetry of Deuteron Photodisintegration in the Energy Region $E_?=1.1-2.3$ GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zachariou, Nicholas [University of South Carolina; et. al.,

    2015-05-01T23:59:59.000Z

    The beam-spin asymmetry, Sigma, for the reaction ?d-->pn has been measured using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility (JLab) for six photon-energy bins, between 1.1 and 2.3 GeV, and proton angles in the center-of-mass frame, thetac.m., between 25degrees and 160degrees. These are the first measurements of beam-spin asymmetries at thetac.m.=90degrees for photon-beam energies above 1.6 GeV, and the first measurements for angles other than thetac.m.=90degrees. The angular and energy dependence of Sigma is expected to aid in the development of QCD-based models to understand the mechanisms of deuteron photodisintegration in the transition region between hadronic and partonic degrees of freedom, where both effective field theories and perturbative QCD cannot make reliable predictions.

  12. Measurement of the generalized form factors near threshold via ?*p ? n?+ at high Q2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Park, K; Adhikari, K P; Adikaram, D; Anghinolfi, M; Baghdasaryan, H; Ball, J; Battaglieri, M; Batourine, V; Bedlinskiy, I; Bennett, R P; et al

    2012-03-26T23:59:59.000Z

    We report the first extraction of the pion-nucleon multipoles near the production threshold for the n?+ channel at relatively high momentum transfer (Q2 up to 4.2 GeV2). The dominance of the s-wave transverse multipole (E0+), expected in this region, allowed us to access the generalized form factor G1 within the light-cone sum rule (LCSR) framework as well as the axial form factor GA. The data analyzed in this work were collected by the nearly 4? CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754-GeV electron beam on a proton target. The differential cross section and the ?-N multipole E0+/GD were measuredmore »using two different methods, the LCSR and a direct multipole fit. The results from the two methods are found to be consistent and almost Q2 independent.« less

  13. pi0 photoproduction on the proton for photon energies from 0.675 to 2.875-GeV

    SciTech Connect (OSTI)

    Michael Dugger; Barry Ritchie; Jacques Ball; Patrick Collins; Evgueni Pasyuk; Richard Arndt; William Briscoe; Igor Strakovski; Ron Workman; Gary Adams; Moscov Amaryan; Pawel Ambrozewicz; Eric Anciant; Marco Anghinolfi; Burin Asavapibhop; G. Asryan; Gerard Audit; Harutyun Avakian; H. Bagdasaryan; Nathan Baillie; Nathan Baltzell; Steve Barrow; Marco Battaglieri; Kevin Beard; Ivan Bedlinski; Ivan Bedlinskiy; Mehmet Bektasoglu; Matthew Bellis; Nawal Benmouna; Barry Berman; Nicola Bianchi; Angela Biselli; Billy Bonner; Sylvain Bouchigny; Sergey Boyarinov; Robert Bradford; Derek Branford; William Brooks; Stephen Bueltmann; Volker Burkert; Cornel Butuceanu; John Calarco; Sharon Careccia; Daniel Carman; Bryan Carnahan; Shifeng Chen; Philip Cole; Alan Coleman; Philip Coltharp; Dieter Cords; Pietro Corvisiero; Donald Crabb; Hall Crannell; John Cummings; Enzo De Sanctis; Raffaella De Vita; Pavel Degtiarenko; Haluk Denizli; Lawrence Dennis; Alexandre Deur; Kahanawita Dharmawardane; Kalvir Dhuga; Richard Dickson; Chaden Djalali; Gail Dodge; Joseph Donnelly; David Doughty; P. Dragovitsch; Steven Dytman; Oleksandr Dzyubak; Hovanes Egiyan; Kim Egiyan; Latifa Elouadrhiri; A. Empl; Paul Eugenio; Renee Fatemi; Gleb Fedotov; Gerald Feldman; Robert Feuerbach; John Ficenec; Tony Forest; Herbert Funsten; Michel Garcon; Gagik Gavalian; Gerard Gilfoyle; Kevin Giovanetti; Francois-Xavier Girod; John Goetz; Ralf Gothe; Keith Griffioen; Michel Guidal; Matthieu Guillo; Nevzat Guler; Lei Guo; Vardan Gyurjyan; Cynthia Hadjidakis; Rafael Hakobyan; John Hardie; D. Heddle; F. Hersman; Kenneth Hicks; Ishaq Hleiqawi; Maurik Holtrop; J. Hu; Marco Huertas; Charles Hyde; Charles Hyde-Wright; Yordanka Ilieva; David Ireland; Boris Ishkhanov; Mark Ito; David Jenkins; Hyon-Suk Jo; Kyungseon Joo; Henry Juengst; Narbe Kalantarians; James Kellie; Mahbubul Khandaker; Kui Kim; Kinney Kim; Wooyoung Kim; Andreas Klein; Franz Klein; Alexei Klimenko; Mike Klusman; Mikhail Kossov; Zebulun Krahn; Laird Kramer; Valery Kubarovsky; Joachim Kuhn; Sebastian Kuhn; Viacheslav Kuznetsov; Jeff Lachniet; Jean Laget; Jorn Langheinrich; David Lawrence; Tsung-shung Lee; Ana Lima; Kenneth Livingston; K. Lukashin; Joseph Manak; Claude Marchand; Leonard Maximon; Simeon McAleer; Bryan McKinnon; John McNabb; Bernhard Mecking; Mac Mestayer; Curtis Meyer; Tsutomu Mibe; Konstantin Mikhaylov; Ralph Minehart; Marco Mirazita; Rory Miskimen; Viktor Mokeev; Kei Moriya; Steven Morrow; Valeria Muccifora; James Mueller; Gordon Mutchler; Pawel Nadel-Turonski; James Napolitano; Rakhsha Nasseripour; Silvia Niccolai; Gabriel Niculescu; Maria-Ioana Niculescu; Bogdan Niczyporuk; Megh Niroula; Rustam Niyazov; Mina Nozar; Grant O'Rielly; Mikhail Osipenko; Alexander Ostrovidov; K Park; Craig Paterson; Sasha Philips; Joshua Pierce; Nikolay Pivnyuk; Dinko Pocanic; Oleg Pogorelko; S. Pozdniakov; Barry Preedom; John Price; Yelena Prok; Dan Protopopescu; Liming Qin; Brian Raue; Gregory Riccardi; Giovanni Ricco; Marco Ripani; Federico Ronchetti; Guenther Rosner; Patrizia Rossi; David Rowntree; Philip Rubin; Franck Sabatie; Julian Salamanca; Carlos Salgado; Joseph Santoro; Vladimir Sapunenko; Reinhard Schumacher; Vladimir Serov; Aziz Shafi; Youri Sharabian; J. Shaw; Sebastio Simionatto; Alexander Skabelin; Elton Smith; Lee Smith; Daniel Sober; M. Spraker; Aleksey Stavinskiy; Samuel Stepanyan; Stepan Stepanyan; Burnham Stokes; Paul Stoler; Steffen Strauch; Mauro Taiuti; Simon Taylor; David Tedeschi; Ulrike Thoma; R. Thompson; Avtandil Tkabladze; Svyatoslav Tkachenko; Luminita Todor; Clarisse Tur; Maurizio Ungaro; Michael Vineyard; Alexander Vlassov; Xue kai Wang; Lawrence Weinstein; Henry Weller; Dennis Weygand; M. Williams; Elliott Wolin; M.H. Wood; A. Yegneswaran; Jae-Chul Yun; Lorenzo Zana; Jixie Zhang

    2007-07-23T23:59:59.000Z

    Differential cross sections for the reaction $\\gamma p \\to p \\pi^0$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.675 to 2.875 GeV. The results reported here possess greater accuracy in the absolute normalization than previous measurements. They disagree with recent CB-ELSA measurements for the process at forward scattering angles. Agreement with the SAID and MAID fits is found below 1 GeV. The present set of cross sections has been incorporated into the SAID database, and exploratory fits have been extended to 3 GeV. Resonance couplings have been extracted and compared to previous determinations.

  14. The In-medium Mass and Widths of Light Vector Mesons

    SciTech Connect (OSTI)

    Djalali, C.; Paolone, M. [University of South Carolina, Department of Physics and Astronomy, Columbia, SC 29208 (United States); Weygand, D. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Wood, M. H. [Canisius College, Department of Physics, Buffalo, NY 14208 (United States); Nasseripour, R. [George Washington University, Department of Physics, Washington, DC 20052 (United States)

    2011-05-23T23:59:59.000Z

    Partial restoration of chiral symmetry in ordinary nuclear matter suggests the modification of properties of vector mesons, such as a shift in mass and/or a change of width. Photoproduction of vector mesons off nuclei were performed at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). The properties of the {rho}, {omega} and {phi} mesons were investigated via their rare leptonic decay to e+e-. This decay channel has an advantage over hadronic modes as it eliminates final state interactions in the nuclear matter. After subtracting the combinatorial background, the meson mass distributions were extracted for each of the nuclear targets. No significant mass shift is observed, however substantial increase in the widths of the mesons is reported.

  15. Precision measurements of $g_1$ of the proton and the deuteron with 6 GeV electrons

    E-Print Network [OSTI]

    Y. Prok; P. Bosted; N. Kvaltine; K. P. Adhikari; D. Adikaram; M. Aghasyan; M. J. Amaryan; M. D. Anderson; S. Anefalos Pereira; H. Avakian; H. Baghdasaryan; J. Ball; N. A. Baltzell; M. Battaglieri; A. S. Biselli; J. Bono; W. J. Briscoe; J. Brock; W. K. Brooks; S. Bültmann; V. D. Burkert; C. Carlin; D. S. Carman; A. Celentano; S. Chandavar; L. Colaneri; P. L. Cole; M. Contalbrigo; O. Cortes; D. Crabb; V. Crede; A. D'Angelo; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; G. E. Dodge; D. Doughty; R. Dupre; A. El Alaoui; L. El Fassi; L. Elouadrhiri; G. Fedotov; S. Fegan; R. Fersch; J. A. Fleming; T. A. Forest; M. Garcon; N. Gevorgyan; Y. Ghandilyan; G. P. Gilfoyle; F. X. Girod; K. L. Giovanetti; J. T. Goetz; W. Gohn; R. W. Gothe; K. A. Griffioen; B. Guegan; N. Guler; K. Haffidi; C. Hanretty; N. Harrison; M. Hattawy; K. Hicks; D. Ho; M. Holtrop; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; E. L. Isupov; S. Jawalkar; X. Jiang; H. S. Jo; K. Joo; N. Kalantarians; C. Keith; D. Keller; M. Khandaker; A. Kim; W. Kim; A. Klein; F. J. Klein; S. Koirala; V. Kubarovsky; S. E. Kuhn; S. V. Kuleshov; P. Lenisa; K. Livingston; H. Y. Lu; I . J. D. MacGregor; N. Markov; M. Mayee; B. McKinnon; D. Meekins; T. Mineeva; M. Mirazita; V. Mokeev; R. A. Montgomery; H. Moutarde; A Movsisyan; E. Munevar; C. Munoz Camacho; P. Nadel-Turonski; S. Niccolai; G. Niculescu; I. Niculescu; M. Osipenko; A. I. Ostrovidov; L. L. Pappalardo; R. Paremuzyan; K. Park; P. Peng; J. J. Phillips; J. Pierce; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; S. Procureur; D. Protopopescu; A. J. R. Puckett; B. A. Raue; D. Rimal; M. Ripani; A. Rizzo; G. Rosner; P. Rossi; P. Roy; F. Sabatié; M. S. Saini; C. Salgado; D. Schott; R. A. Schumacher; E. Seder; Y. G. Sharabian; A. Simonyan; C. Smith; G. Smith; D. I. Sober; D. Sokhan; S. S. Stepanyan; S. Stepanyan; I. I. Strakovsky; S. Strauch; V. Sytnik; M. Taiuti; W. Tang; S. Tkachenko; M. Ungaro; B . Vernarsky; A. V. Vlassov; H. Voskanyan; E. Voutier; N. K. Walford; D . P. Watts; L. B. Weinstein; N. Zachariou; L. Zana; J. Zhang; B. Zhao; Z. W. Zhao; I. Zonta; for the CLAS collaboration

    2014-04-24T23:59:59.000Z

    The inclusive polarized structure functions of the proton and deuteron, g1p and g1d, were measured with high statistical precision using polarized 6 GeV electrons incident on a polarized ammonia target in Hall B at Jefferson Laboratory. Electrons scattered at lab angles between 18 and 45 degrees were detected using the CEBAF Large Acceptance Spectrometer (CLAS). For the usual DIS kinematics, Q^2>1 GeV^2 and the final-state invariant mass W>2 GeV, the ratio of polarized to unpolarized structure functions g1/F1 is found to be nearly independent of Q^2 at fixed x. Significant resonant structure is apparent at values of W up to 2.3 GeV. In the framework of perturbative QCD, the high-W results can be used to better constrain the polarization of quarks and gluons in the nucleon, as well as high-twist contributions.

  16. K{sub S} Lambda Photoproduction On The Neutron Within The Resonance Region

    SciTech Connect (OSTI)

    Taylor, Charles E. [Idaho State University, Pocatello, ID (United States); Cole, Philip L. [Idaho State University, Pocatello, ID (United States)

    2014-01-01T23:59:59.000Z

    We report some preliminary differential cross section results for the gammad --> K{sub S} Lambda(p) reaction using a circularly-polarized photon beam and an unpolarized LD{sub 2} target. The data was collected at the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. For this study the photon energy ranged from 1.3 to 2.53 GeV, which covers from the reaction threshold through the nucleon resonance regimes. The acceptance- and flux-corrected yields show peaks at the center-of mass energies W = 1.7 and W = 1.9 GeV. These first-time results will aid in unraveling the spectrum of non-strange excited baryons.

  17. Probing the nucleon structure with SIDIS at Jefferson Lab

    SciTech Connect (OSTI)

    Pereira, Sergio Anafalos [INFN-Frascati

    2013-01-01T23:59:59.000Z

    In recent years, measurements of azimuthal moments of polarized hadronic cross sections in hard processes have emerged as a powerful tool to probe nucleon structure. Many experiments worldwide are currently trying to pin down various effects related to nucleon structure through Semi-Inclusive Deep-Inelastic Scattering (SIDIS). Azimuthal distributions of final-state particles in semi-inclusive deep inelastic scattering, in particular, are sensitive to the orbital motion of quarks and play an important role in the study of Transverse Momentum Dependent parton distribution functions (TMDs) of quarks in the nucleon. The CLAS spectrometer, installed in Hall-B at Jefferson Lab, has collected semi-inclusive data using the CEBAF 6 GeV polarized electron beam on polarized solid NH{sub 3} and ND{sub 3} targets. An overview of these measurements is presented.

  18. Cross Sections for the $?p \\to K^{*0}?^+$ Reaction at $E_?= 1.7 - 3.0$ GeV

    E-Print Network [OSTI]

    I. Hleiqawi; K. Hicks; D. Carman; T. Mibe

    2007-08-14T23:59:59.000Z

    Differential cross sections for the reaction $\\gamma p \\to K^{*0} \\Sigma^+$ are presented at nine bins in photon energy in the range from 1.7 to 3.0 GeV. The \\kstar was detected by its decay products, $K^+\\pi^-$, in the CLAS detector at Jefferson Lab. These data are the first \\kstar photoproduction cross sections ever published over a broad range of angles. Comparison with a theoretical model based on the vector and tensor $K^*$-quark couplings shows good agreement with the data in general, after adjusting the model's two parameters in a fit to our data. Disagreement between the data at forward angles and the global angle-energy fit to the model suggests that the role of scalar $\\kappa$ meson exchange in $t$-channel diagrams should be investigated.

  19. Precision measurements of g1 of the proton and the deuteron with 6 GeV electrons

    SciTech Connect (OSTI)

    Prok, Yelena; Bosted, Peter; Kvaltine, Nicholas; Adhikari, Krishna; Adikaram-Mudiyanselage, Dasuni; Aghasyan, Mher; Amaryan, Moskov; Anderson, Mark; Anefalos Pereira, Sergio; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Ball, Jacques; Baltzell, Nathan; Battaglieri, Marco; Biselli, Angela; Bono, Jason; Briscoe, William; Brock, Joseph; Brooks, William; Bueltmann, Stephen; Burkert, Volker; Carlin, Christopher; Carman, Daniel; Celentano, Andrea; Chandavar, Shloka; Colaneri, Luca; Cole, Philip; Contalbrigo, Marco; Cortes, Olga; Crabb, Donald; Crede, Volker; D'Angelo, Annalisa; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Deur, Alexandre; Djalali, Chaden; Dodge, Gail; Doughty, David; Dupre, Raphael; El Alaoui, Ahmed; El Fassi, Lamiaa; Elouadrhiri, Latifa; Fedotov, Gleb; Fegan, Stuart; Fersch, Robert; Fleming, Jamie; Forest, Tony; Garcon, Michel; Gevorgyan, Nerses; Ghandilyan, Yeranuhi; Gilfoyle, Gerard; Girod-Gard, Francois-Xavier; Giovanetti, Kevin; Goetz, John; Gohn, Wesley; Gothe, Ralf; Griffioen, Keith; Guegan, Baptiste; Guler, Nevzat; Hafidi, Kawtar; Hanretty, Charles; Harrison, Nathan; Hattawy, Mohammad; Hicks, Kenneth; Ho, Dao; Holtrop, Maurik; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Jawalkar, Sucheta; Jiang, Xiaodong; Jo, Hyon-Suk; Joo, Kyungseon; Kalantarians, Narbe; Keith, Christopher; Keller, Daniel; Khandaker, Mahbubul; Kim, Andrey; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Koirala, Suman; Kubarovsky, Valery; Kuhn, Sebastian; Kuleshov, Sergey; Lenisa, Paolo; Livingston, Kenneth; Lu, Haiyun; MacGregor, Ian; Markov, Nikolai; Mayer, Michael; McKinnon, Bryan; Meekins, David; Mineeva, Taisiya; Mirazita, Marco; Mokeev, Viktor; Montgomery, Rachel; MOUTARDE, Herve; Movsisyan, Aram; Munevar Espitia, Edwin; Munoz Camacho, Carlos; Nadel-Turonski, Pawel; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria; Osipenko, Mikhail; Ostrovidov, Alexander; Pappalardo, Luciano; Paremuzyan, Rafayel; Park, K.; Peng, Peng; Phillips, J.J.; Pierce, Joshua; Pisano, Silvia; Pogorelko, Oleg; Pozdniakov, Serguei; Price, John; Procureur, Sebastien; Protopopescu, Dan; Puckett, Andrew; Raue, Brian; Rimal, Dipak; Ripani, Marco; Rizzo, Alessandro; Rosner, Guenther; Rossi, Patrizia; Roy, Priyashree; Sabatie, Franck; Saini, Mukesh; Salgado, Carlos; Schott, Diane; Schumacher, Reinhard; Seder, Erin; Sharabian, Youri; Simonyan, Ani; Smith, Claude; Smith, Gregory; Sober, Daniel; Sokhan, Daria; Stepanyan, Stepan; Stepanyan, Samuel; Strakovski, Igor; Strauch, Steffen; Sytnik, Valeriy; Taiuti, Mauro; Tang, Wei; Tkachenko, Svyatoslav; Ungaro, Maurizio; Vernarsky, Brian; Vlasov, Alexander; Voskanyan, Hakob; Voutier, Eric; Walford, Natalie; Watts, Daniel; Weinstein, Lawrence; Zachariou, Nicholas; Zana, Lorenzo; Zhang, Jixie; Zhao, Bo; Zhao, Zhiwen; Zonta, Irene

    2014-08-01T23:59:59.000Z

    The inclusive polarized structure functions of the proton and deuteron, g1p and g1d, were measured with high statistical precision using polarized 6 GeV electrons incident on a polarized ammonia target in Hall B at Jefferson Laboratory. Electrons scattered at lab angles between 18 and 45 degrees were detected using the CEBAF Large Acceptance Spectrometer (CLAS). For the usual DIS kinematics, Q^2>1 GeV^2 and the final-state invariant mass W>2 GeV, the ratio of polarized to unpolarized structure functions g1/F1 is found to be nearly independent of Q^2 at fixed x. Significant resonant structure is apparent at values of W up to 2.3 GeV. In the framework of perturbative QCD, the high-W results can be used to better constrain the polarization of quarks and gluons in the nucleon, as well as high-twist contributions.

  20. NN Correlations Measured in 3He(e,e'pp)n

    E-Print Network [OSTI]

    L. B. Weinstein; R. Niyazov

    2002-10-01T23:59:59.000Z

    We have measured the $^3$He(e,e$'$pp)n{} reaction in the Jefferson Lab CLAS with 2.2 and 4.4 GeV electrons. We looked at the energy distribution of events with all three nucleons at high momentum (p > 250 MeV/c). This distribution has peaks where two nucleons each have 20% or less of the energy transfer (ie: the third or `leading' nucleon carries most of the kinetic energy). The angular distribution of these two `fast' nucleons shows a very large back-to-back peak, indicating the effect of correlations. While there is some theoretical disagreement, experimental evidence, plus calculations at lower energy by W. Glockle, indicates that these events are primarily sensitive to NN correlations.

  1. Measurement of the generalized form factors near threshold via ?*p ? n?+ at high Q2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Park, K; Adhikari, K P; Adikaram, D; Anghinolfi, M; Baghdasaryan, H; Ball, J; Battaglieri, M; Batourine, V; Bedlinskiy, I; Bennett, R P; Biselli, A S; Bookwalter, C; Boiarinov, S; Branford, D; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Cole, P L; Contalbrigo, M; Crede, V; D'Angelo, A; Daniel, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Doughty, D; Dupre, R; El Alaoui, A; El Fassi, L; Euginio, P; Fedotov, G; Fradi, A; Gabrielyan, M Y; Gevorgyan, N; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Gohn, W; Golovatch, E; Graham, L; Griffioen, K A; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Heddle, D; Hicks, K; Holtrop, M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jenkins, D; Jo, H S; Joo, K; Khandaker, M; Khertarpal, P; Kim, A; Kim, W; Klein, F J; Kubarovsky, A; Kubarovsky, V; Kuhn, S E; Kuleshov, S V; Kvaltine, N D; Livingston, K; Lu, H Y; MacGregor, J D; Markov, N; Mayer, M; McKinnon, B; Mestayer, M D; Meyer, C A; Mineeva, T; Mirazita, M; Mokeev, V; Moutarde, H; Munevar, E; Nadel-Turonski, P; Nasseripour, R; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Paolone, M; Pappalardo, L; Paremuzyan, R; Park, S; Anefalos Pereira, S; Phelps, E; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Prok, Y; Ricco, G; Rimal, D; Ripani, M; Ritchie, B G; Rosner, G; Rossi, P; Sabati ee, F; Saini, M S; Salgado, C; Schott, D; Schumacher, R A; Seraydaryan, H; Sharabian, Y G; Smith, E S; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strakovsky, I I; Strauch, S; Taiuti, M; Tang, W; Taylor, C E; Tian, Y; Tkachenko, S; Trivedi, A; Ungaro, M; Vernarsky, B; Vlassov, A V; Voutier, E; Watts, D P; Weygand, D P; Wood, M H; Zachariou, N; Zhao, B; Zhao, Z W

    2012-03-26T23:59:59.000Z

    We report the first extraction of the pion-nucleon multipoles near the production threshold for the n?+ channel at relatively high momentum transfer (Q2 up to 4.2 GeV2). The dominance of the s-wave transverse multipole (E0+), expected in this region, allowed us to access the generalized form factor G1 within the light-cone sum rule (LCSR) framework as well as the axial form factor GA. The data analyzed in this work were collected by the nearly 4? CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754-GeV electron beam on a proton target. The differential cross section and the ?-N multipole E0+/GD were measured using two different methods, the LCSR and a direct multipole fit. The results from the two methods are found to be consistent and almost Q2 independent.

  2. Determination of the Beam-Spin Asymmetry of Deuteron Photodisintegration in the Energy Region $E_?=1.1-2.3$ GeV

    E-Print Network [OSTI]

    Nicholas Zachariou; Yordanka Ilieva; Nikolay Ya. Ivanov; Misak M Sargsian; Robert Avakian; Gerald Feldman; Pawel Nadel-Turonski; K. P. Adhikari; D. Adikaram; M. D. Anderson; S. Anefalos Pereira; H. Avakian; R. A. Badui; N. A. Baltzell; M. Battaglieri; V. Baturin; I. Bedlinskiy; A. S. Biselli; W. J. Briscoe; W. K. Brooks; V. D. Burkert; T. Cao; D. S. Carman; A. Celentano; S. Chandavar; G. Charles; L. Colaneri; P. L. Cole; N. Compton; M. Contalbrigo; O. Cortes; V. Crede; A. D'Angelo; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; R. Dupre; H. Egiyan; A. El Alaoui; L. El Fassi; L. Elouadrhiri; G. Fedotov; S. Fegan; A. Filippi; J. A. Fleming; T. A. Forest; A. Fradi; N. Gevorgyan; Y. Ghandilyan; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; D. I. Glazier; E. Golovatch; R. W. Gothe; K. A. Griffioen; M. Guidal; K. Hafidi; C. Hanretty; N. Harrison; M. Hattawy; K. Hicks; D. Ho; M. Holtrop; S. M. Hughes; D. G. Ireland; B. S. Ishkhanov; E. L. Isupov; H. Jiang; H. S. Jo; K. Joo; D. Keller; G. Khachatryan; M. Khandaker; A. Kim; W. Kim; F. J. Klein; V. Kubarovsky; P. Lenisa; K. Livingston; H. Y. Lu; I . J . D. MacGregor; N. Markov; P. T. Mattione; B. McKinnon; T. Mineeva; M. Mirazita; V. I. Mokeeev; R. A. Montgomery; H. Moutarde; C. Munoz Camacho; L. A. Net; S. Niccolai; G. Niculescu; I. Niculescu; M. Osipenko; A. I. Ostrovidov; K. Park; E. Pasyuk; W. Phelps; J. J. Phillips; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; S. Procureur; Y. Prok; D. Protopopescu; A. J. R. Puckett; M. Ripani; A. Rizzo; G. Rosner; P. Rossi; P. Roy; F. Sabatié; C. Salgado; D. Schott; R. A. Schumacher; E. Seder; I. Senderovich; Y. G. Sharabian; Iu. Skorodumina; G. D. Smith; D. I. Sober; D. Sokhan; N. Sparveris; S. Stepanyan; S. Strauch; V. Sytnik; M. Taiuti; Ye Tian; M. Ungaro; H. Voskanyan; E. Voutier; N. K. Walford; D. Watts; X. Wei; M. H. Wood; L. Zana; J. Zhang; Z. W. Zhao; I. Zonta; for the CLAS collaboration

    2015-03-18T23:59:59.000Z

    The beam-spin asymmetry, $\\Sigma$, for the reaction $\\gamma d\\rightarrow pn$ has been measured using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility (JLab) for six photon-energy bins between 1.1 and 2.3 GeV, and proton angles in the center-of-mass frame, $\\theta_{c.m.}$, between $25^\\circ$ and $160^\\circ$. These are the first measurements of beam-spin asymmetries at $\\theta_{c.m.}=90^\\circ$ for photon-beam energies above 1.6 GeV, and the first measurements for angles other than $\\theta_{c.m.}=90^\\circ$. The angular and energy dependence of $\\Sigma$ is expected to aid in the development of QCD-based models to understand the mechanisms of deuteron photodisintegration in the transition region between hadronic and partonic degrees of freedom, where both effective field theories and perturbative QCD cannot make reliable predictions.

  3. Role of high-spin hyperon resonances in the reaction of {gamma}p{yields}K{sup +}K{sup +}{Xi}{sup -}

    SciTech Connect (OSTI)

    Man, J. Ka Shing [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States); Oh, Yongseok [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Excited Baryon Analysis Center, Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Asia Pacific Center for Theoretical Physics, POSTECH, Pohang 790-784 (Korea, Republic of); Nakayama, K. [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States); Institut fuer Kernphysik, Forschungszentrum Juelich, D-52425 Juelich (Germany)

    2011-05-15T23:59:59.000Z

    The recent data taken by the CLAS Collaboration at the Thomas Jefferson National Accelerator Facility for the reaction of {gamma}p{yields}K{sup +}K{sup +}{Xi}{sup -} are reanalyzed within a relativistic meson-exchange model of hadronic interactions. The present model is an extension of the one developed in an earlier work by Nakayama, Oh, and Haberzettl [Phys. Rev. C 74, 035205 (2006)]. In particular, the role of the spin-5/2 and -7/2 hyperon resonances, which were not included in the previous model, is investigated in the present study. It is shown that the contribution of the {Sigma}(2030) hyperon having spin-7/2 and positive parity has a key role to bring the model predictions into a fair agreement with the measured data for the K{sup +}{Xi}{sup -} invariant mass distribution.

  4. Design and realization of a facility for the characterization of Silicon Avalanche PhotoDiodes

    E-Print Network [OSTI]

    Celentano, Andrea; De Vita, Raffaella; Fegan, Stuart; Mini, Giuseppe; Nobili, Gianni; Ottonello, Giacomo; Parodi, Franco; Rizzo, Alessandro; Zonta, Irene

    2015-01-01T23:59:59.000Z

    We present the design, construction, and performance of a facility for the characterization of Silicon Avalanche Photodiodes in the operating temperature range between -2 $^\\circ$C and 25 $^\\circ$C. The system can simultaneously measure up to 24 photo-detectors, in a completely automatic way, within one day of operations. The measured data for each sensor are: the internal gain as a function of the bias voltage and temperature, the gain variation with respect to the bias voltage, and the dark current as a function of the gain. The systematic uncertainties have been evaluated during the commissioning of the system to be of the order of 1%. This paper describes in detail the facility design and layout, and the procedure employed to characterize the sensors. The results obtained from the measurement of the 380 Avalanche Photodiodes of the CLAS12-Forward Tagger calorimeter detector are then reported, as the first example of the massive usage of the facility.

  5. Design and realization of a facility for the characterization of Silicon Avalanche PhotoDiodes

    E-Print Network [OSTI]

    Andrea Celentano; Luca Colaneri; Raffaella De Vita; Stuart Fegan; Giuseppe Mini; Gianni Nobili; Giacomo Ottonello; Franco Parodi; Alessandro Rizzo; Irene Zonta

    2015-04-07T23:59:59.000Z

    We present the design, construction, and performance of a facility for the characterization of Silicon Avalanche Photodiodes in the operating temperature range between -2 $^\\circ$C and 25 $^\\circ$C. The system can simultaneously measure up to 24 photo-detectors, in a completely automatic way, within one day of operations. The measured data for each sensor are: the internal gain as a function of the bias voltage and temperature, the gain variation with respect to the bias voltage, and the dark current as a function of the gain. The systematic uncertainties have been evaluated during the commissioning of the system to be of the order of 1%. This paper describes in detail the facility design and layout, and the procedure employed to characterize the sensors. The results obtained from the measurement of the 380 Avalanche Photodiodes of the CLAS12-Forward Tagger calorimeter detector are then reported, as the first example of the massive usage of the facility.

  6. Near-threshold Photoproduction of Phi Mesons from Deuterium

    E-Print Network [OSTI]

    X. Qian; W. Chen; H. Gao; K. Hicks; K. Kramer; J. M. Laget; T. Mibe; Y. Qiang; S. Stepanyan; D. J. Tedeschi; W. Xu; K. P. Adhikari; M. Amaryan; M. Anghinolfi; J. Ball; M. Battaglieri; V. Batourine; I. Bedlinskiy; M. Bellis; A. S. Biselli; C. Bookwalter; D. Branford; W. J. Briscoe; W. K. Brooks; V. D. Burkert; S. L. Careccia; D. S. Carman; P. L. Cole; P. Collins; V. Crede; A. D'Angelo; A. Daniel; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; B. Dey; S. Dhamija; C. Djalali; D. Doughty; R. Dupre; H. Egiyan; A. El Alaoui; P. Eugenio; S. Fegan; M. Y. Gabrielyan; N. Gevorgyan; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; W. Gohn; R. W. Gothe; L. Graham; K. A. Griffioen; M. Guidal; L. Guo; K. Hafidi; H. Hakobyan; C. Hanretty; N. Hassall; M. Holtrop; Y. Ilieva; D. G. Ireland; S. S. Jawalkar; H. S. Jo; K. Joo; D. Keller; M. Khandaker; P. Khetarpal; A. Kim; W. Kim; A. Klein; F. J. Klein; P. Konczykowski; V. Kubarovsky; S. V. Kuleshov; V. Kuznetsov; K. Livingston; D. Martinez; M. Mayer; J. McAndrew; M. E. McCracken; B. McKinnon; C. A. Meyer; K. Mikhailov; T. Mineeva; M. Mirazita; V. Mokeev; B. Moreno; K. Moriya; B. Morrison; H. Moutarde; E. Munevar; P. Nadel-Turonski; A. Ni; S. Niccolai; I. Niculescu; M. R. Niroula; M. Osipenko; A. I. Ostrovidov; R. Paremuzyan; K. Park; S. Park; S. Anefalos Pereira; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; S. Procureur; D. Protopopescu; G. Ricco; M. Ripani; B. G. Ritchie; G. Rosner; P. Rossi; F. Sabatié; M. S. Saini; C. Salgado; D. Schott; R. A. Schumacher; E. Seder; H. Seraydaryan; Y. G. Sharabian; E. S. Smith; G. D. Smith; D. I. Sober; D. Sokhan; S. S. Stepanyan; P. Stoler; I. I. Strakovsky; S. Strauch; M. Taiuti; C. E. Taylor; S. Tkachenko; M. Ungaro; B . Vernarsky; M. F. Vineyard; E. Voutier; L. B. Weinstein; D. P. Weygand; M. H. Wood; N. Zachariou; L. Zana; J. Zhang; B. Zhao; Z. W. Zhao

    2010-12-14T23:59:59.000Z

    We report the first measurement of the differential cross section on $\\phi$-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, $K^+$ and $K^-$ near the theoretical production threshold of 1.57 GeV. The extracted differential cross sections $\\frac{d\\sigma}{dt}$ for the initial photon energy from 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. This experiment establishes a baseline for a future experimental search for an exotic $\\phi$-N bound state from heavier nuclear targets utilizing subthreshold/near-threshold production of $\\phi$ mesons.

  7. First measurement of the helicity asymmetry E in $?$ photoproduction on the proton

    E-Print Network [OSTI]

    I. Senderovich; B. T. Morrison; M. Dugger; B. G. Ritchie; E. Pasyuk; R. Tucker; J. Brock; C. Carlin; C. D. Keith; D. G. Meekins; M. L. Seely; D. R; M. D; P. Collins; K. P. Adhikari; D. Adikaram; Z. Akbar; M. D. Anderson; S. Anefalos Pereira; R. A. Badui; J. Ball; N. A. Baltzell; M. Battaglieri; V. Batourine; I. Bedlinskiy; A. S. Biselli; S. Boiarinov; W. J. Briscoe; W. K. Brooks; V. D. Burkert; D. S. Carman; A. Celentano; S. Chandavar; G. Charles; L. Colaneri; P. L. Cole; M. Contalbrigo; O. Cortes; V. Crede; A. D'Angelo; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; R. Dupre; H. Egiyan; A. El Alaoui; L. El Fassi; A. Fradi; L. Elouadrhiri; P. Eugenio; G. Fedotov; S. Fegan; A. Filippi; J. A. Fleming; B. Garillon; Y. Ghandilyan; G. P. Gilfoyle; K. L. Giovanetti; F. -X. Girod; D. I. Glazier; J. T. Goetz; W. Gohn; E. Golovatch; R. W. Gothe; K. A. Griffioen; M. Guidal; L. Guo; K. Hafidi; H. Hakobyan; C. Hanretty; M. Hattawy; K. Hicks; D. Ho; M. Holtrop; S. M. Hughes; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; D. Jenkins; H. Jiang; H. S. Jo; K. Joo; S. Joosten; D. Keller; G. Khachatryan; M. Khandaker; A. Kim; F. J. Klein; V. Kubarovsky; M. C. Kunkel; P. Lenisa; K. Livingston; H. Y. Lu; I. J. D. MacGregor; P. Mattione; B. McKinnon; C. A. Meyer; T. Mineeva; V. Mokeev; R. A. Montgomery; A. Movsisyan; C. Munoz Camacho; P. Nadel-Turonski; L. A. Net; S. Niccolai; G. Niculescu; I. Niculescu; M. Osipenko; K. Park; S. Park; P. Peng; W. Phelps; S. Pisano; O. Pogorelko; J. W. Price; Y. Prok; A. J. R. Puckett; M. Ripani; A. Rizzo; G. Rosner; P. Roy; F. Sabatie; C. Salgado; D. Schott; R. A. Schumacher; E. Seder; A. Simonyan; Iu. Skorodumina; G. D. Smith; D. I. Sober; D. Sokhan; N. Sparveris; S. Stepanyan; P. Stoler; I. I. Strakovsky; S. Strauch; V. Sytnik; Ye Tian; M. Ungaro; H. Voskanyan; E. Voutier; N. K. Walford; X. Wei; M. H. Wood; N. Zachariou; L. Zana; J. Zhang; Z. W. Zhao; I. Zonta

    2015-07-01T23:59:59.000Z

    Results are presented for the first measurement of the double-polarization helicity asymmetry E for the $\\eta$ photoproduction reaction $\\gamma p \\rightarrow \\eta p$. Data were obtained using the FROzen Spin Target (FROST) with the CLAS spectrometer in Hall B at Jefferson Lab, covering a range of center-of-mass energy W from threshold to 2.15 GeV and a large range in center-of-mass polar angle. As an initial application of these data, the results have been incorporated into the J\\"ulich model to examine the case for the existence of a narrow $N^*$ resonance between 1.66 and 1.70 GeV. The addition of these data to the world database results in marked changes in the predictions for the E observable using that model. Further comparison with several theoretical approaches indicates these data will significantly enhance our understanding of nucleon resonances.

  8. Measurement of the generalized form factors near threshold via $?^* p \\to n?^+$ at high $Q^2$

    E-Print Network [OSTI]

    Kijun Park; Ralf Gothe; Krishna Adhikari; Dasuni Adikaram-Mudiyanselage; Marco Anghinolfi; Hovhannes Baghdasaryan; Jacques Ball; Marco Battaglieri; Vitaly Baturin; Ivan Bedlinskiy; Robert Bennett; Angela Biselli; Craig Bookwalter; Sergey Boyarinov; Derek Branford; William Briscoe; William Brooks; Volker Burkert; Daniel Carman; Andrea Celentano; Shloka Chandavar; Gabriel Charles; Philip Cole; Marco Contalbrigo; Volker Crede; Annalisa D'Angelo; Aji Daniel; Natalya Dashyan; Raffaella De Vita; Enzo De Sanctis; Alexandre Deur; Chaden Djalali; David Doughty; Raphael Dupre; Ahmed El Alaoui; Lamiaa Elfassi; Paul Eugenio; Gleb Fedotov; Ahmed Fradi; Marianna Gabrielyan; Nerses Gevorgyan; Gerard Gilfoyle; Kevin Giovanetti; Francois-Xavier Girod; John Goetz; Wesley Gohn; Evgeny Golovach; Lewis Graham; Keith Griffioen; Michel Guidal; Lei Guo; Kawtar Hafidi; Hayk Hakobyan; Charles Hanretty; David Heddle; Kenneth Hicks; Maurik Holtrop; Yordanka Ilieva; David Ireland; Boris Ishkhanov; Evgeny Isupov; David Jenkins; Hyon-Suk Jo; Kyungseon Joo; Mahbubul Khandaker; Puneet Khetarpal; Andrey Kim; Wooyoung Kim; Andreas Klein; Franz Klein; A. Kubarovsky; Valery Kubarovsky; Sebastian Kuhn; Sergey Kuleshov; Nicholas Kvaltine; Kenneth Livingston; Haiyun Lu; Ian MacGregor; Nikolai Markov; Michael Mayer; Bryan McKinnon; Mac Mestayer; Curtis Meyer; Taisiya Mineeva; Marco Mirazita; Viktor Mokeev; Herve Moutarde; Edwin Munevar Espitia; Pawel Nadel-Turonski; Rakhsha Nasseripour; Silvia Niccolai; Gabriel Niculescu; Maria-Ioana Niculescu; Mikhail Osipenko; Alexander Ostrovidov; Michael Paolone; Luciano Pappalardo; Rafayel Paremuzyan; Seungkyung Park; Sergio Pereira; Evan Phelps; Silvia Pisano; Oleg Pogorelko; Sergey Pozdnyakov; John Price; Sebastien Procureur; Yelena Prok; Giovanni Ricco; Dipak Rimal; Marco Ripani; Barry Ritchie; Guenther Rosner; Patrizia Rossi; Franck Sabatie; Mukesh Saini; Carlos Salgado; Diane Schott; Reinhard Schumacher; Heghine Seraydaryan; Youri Sharabian; Elton Smith; Gregory Smith; Daniel Sober; Daria Sokhan; Samuel Stepanyan; Stepan Stepanyan; Paul Stoler; Igor Strakovski; Steffen Strauch; Mauro Taiuti; Wei Tang; Charles Taylor; Ye Tian; Svyatoslav Tkachenko; Arjun Trivedi; Maurizio Ungaro; Brian Vernarsky; Alexander Vlasov; Eric Voutier; Daniel Watts; Dennis Weygand; Michael Wood; Nicholas Zachariou; Bo Zhao; Zhiwen Zhao; N. Kalantarians; C. E. Hyde

    2012-02-21T23:59:59.000Z

    We report the first extraction of the pion-nucleon multipoles near the production threshold for the $n\\pi^+$ channel at relatively high momentum transfer ($Q^2$ up to 4.2 $\\rm{GeV^2}$). The dominance of the s-wave transverse multipole ($E_{0+}$), expected in this region, allowed us to access the generalized form factor $G_1$ within the light-cone sum rule (LCSR) framework as well as the axial form factor $G_A$. The data analyzed in this work were collected by the nearly $4\\pi$ CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754 $\\rm{GeV}$ electron beam on a proton target. The differential cross section and the $\\pi-N$-multipole $E_{0+}/G_D$ were measured using two different methods, the LCSR and a direct multipole fit. The results from the two methods are found to be consistent and almost $Q^2$ independent.

  9. Measurement Of Differential Cross Sections Of p(e,e'{pi}{sup +})n For High-Lying Resonances At Q{sup 2} < 5 GeV{sup 2}

    SciTech Connect (OSTI)

    Park, Kijun

    2014-01-01T23:59:59.000Z

    The exclusive electro-production process ep -> e'n{pi}{sup +} was measured in the range of the invariant mass for n{pi}{sup +} system 1.6 GeV <= W <= 2.0 GeV, and the photon virtuality 1.8 GeV{sup 2} <= Q{sup 2} <= 4.0 GeV{sup 2} using CLAS. For the first time, these kinematics are probed in exclusive {pi}{sup +} production from the protons with nearly full coverage in the azimuthal and polar angles of the n{pi}{sup +} center-of-mass system. In this experiment, approximately 39,000 differential cross-section data points were measured. In this proceeding, preliminary results of our latest analysis work are presented on differential cross sections and structure functions as well as Legendre Moments.

  10. Upper limits for the photoproduction cross section for the Phi--(1860) pentaquark state off the deuteron

    SciTech Connect (OSTI)

    Hovanes Egiyan

    2012-01-01T23:59:59.000Z

    We searched for the {Phi}{sup --}(1860) pentaquark in the photoproduction process off the deuteron in the {Xi}{sup -} {pi}{sup -} decay channel using CLAS. The invariant mass spectrum of the {Xi}{sup -} {pi}{sup -} system does not indicate any statistically significant enhancement near the reported mass M = 1.860 GeV. The statistical analysis of the sideband-subtracted mass spectrum yields a 90% confidence level upper limit of 0.7 nb for the photoproduction cross section of {Phi}{sup --}(1860) with a consecutive decay into {Xi}{sup -} {pi}{sup -} in the photon energy range 4.5 GeV < E{sub {gamma}} < 5.5 GeV.

  11. Light Vector Meson Photoproduction off of 1H at Jefferson Lab and p-w Interference in the Leptonic Decay Channel

    SciTech Connect (OSTI)

    Djalali, Chaden [University of Iowa; Paolone, Michael [Temple University, JLAB; Weygand, Dennis; Wood, Mike H. [USC LA, JLAB

    2014-09-01T23:59:59.000Z

    Although the phenomena of r – w interference has been studied at great length in pionic decay channel over the past 50 years, a study of the interference in a purely electromagnetic production and decay channel has never been performed on an elementary proton target until now. The only published photo-production data of the r - w leptonic decay channel was obtained in the early seventies on C and Be. An investigation of the r - w interference on a Hydrogen was recently completed at Jefferson Lab with the CLAS detector. The di-lepton spectra was fit with two inter- fering relativistic Breit-Wigner functions, and the interference phase was extracted. Preliminary results will be compared to the previous experimental studies in nuclei.

  12. A direct measurement of meson-baryon contributions to the electroexcitation of the $N(1675){\\frac{5}{2}}^-$ nucleon resonance

    E-Print Network [OSTI]

    I. G. Aznauryan; V. D. Burkert

    2014-12-03T23:59:59.000Z

    We report on the determination of the electrocouplings for the transition from the proton to the $N^+(1675){\\frac{5}{2}}^-$ resonance state using new differential cross section data on $e p \\rightarrow e\\pi^+ n$ by the CLAS collaboration at $1.8 \\le Q^2 process. The data have been analyzed using two different approaches, the unitary isobar model and fixed-t dispersion relations. The extracted $\\gamma^* p\\rightarrow N(1675){\\frac{5}{2}}^-$ helicity amplitudes show significant coupling through the $A^p_{1/2}$ amplitude for $Q^2 \\le 4$GeV$^2$, while $A^p_{3/2}$ drops much faster and at $Q^2 \\ge 1.8$GeV$^2$ is already much smaller than $A^p_{1/2}$. Both results are consistent with the meson-baryon contributions from the dynamical coupled-channel model.

  13. Spin and parity measurement of the ?(1405) baryon

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Moriya, Kei [Indiana U.; Schumacher, Reinhard A. [Carnegie Mellon U.

    2014-02-01T23:59:59.000Z

    A determination of the spin and parity of the ?(1405) is presented using photoproduction data from the CLAS detector at Jefferson Lab. The reaction ?+p?K++?(1405) is analyzed in the decay channel Lambda(1405)??++?, where the decay distribution to ?+pi- and the variation of the ?+ polarization with respect to the ?(1405) polarization direction determines the parity. The ?(1405) is produced, in the energy range 2.55

  14. Electromagnetic Decay of the $\\Sigma^{0}(1385)$ to $\\Lambda\\gamma$

    SciTech Connect (OSTI)

    Keller, Dustin; Adhikari, Krishna; Adikaram-Mudiyanselage, Dasuni; Aghasyan, Mher; Amaryan, Moscov; Baghdasaryan, Hovhannes; Ball, J P; Ball, Jacques; Battaglieri, Marco; Batourine, V; Bedlinskiy, Ivan; Bennett, Robert; Biselli, Angela; Branford, Derek; Briscoe, Wilbert; Brooks, William; Burkert, Volker; Careccia, Sharon; Carman, Daniel; Casey, Liam; Cole, Philip; Contalbrigo, Marco; Crede, Volker; D& #x27; Angelo, Annalisa; Daniel, AJI; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Deur, Alexandre; Dey, Biplap; Dickson, Richard; Djalali, Chaden; Doughty, David; Dupre, Raphael; Egiyan, Hovanes; El Alaoui, Ahmed; Elfassi, Lamiaa; Eugenio, Paul; Fedotov, Gleb; Fegan, Stuart; Forest, Tony; Gabrielyan, Marianna; Gavalian, Gagik; Gevorgyan, Nerses; Giovanetti, Kevin; Girod, Francois-Xavier; Gohn, Wesley; Golovach, Evgeny; Gothe, Ralf; Graham, Lewis; Guidal, Michel; Guegan, Baptiste; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Holtrop, Maurik; Ilieva, Yordanka; Ireland, David; Isupov, Evgeny; Jawalkar, Sucheta; Jenkins, David; Jo, Hyon-Suk; Joo, Kyungseon; Khandaker, Mahbubul; Khetarpal, Puneet; Kim, Andrey; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Konczykowski, Piotr; Kubarovsky, Valery; Kuleshov, Sergey; Kuznetsov, Viacheslav; Lu, Haiyun; MacGregor, Ian; Markov, Nikolai; McAndrew, Josephine; KcKinnon, Bryan; Meyer, Curtis; Micherdzinska, Anna; Mirazita, Marco; Mokeev, Viktor; Moreno, Brahim; Moriya, Kei; Morrison, Brian; Moutarde, Herve; Munevar Espitia, Edwin; Nadel-Turonski, Pawel; Ni, Andrey; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria-Ioana; Osipenko, Mikhail; Ostrovidov, Alexander; Paremuzyan, Rafayel; Park, Kijun; Park, Sungkyun; Pasyuk, Eugene; Pasyuk, Evgueni; Pereira, Sergio; Pappalardo, Luciano; Pisano, Silvia; Pogorelko, Oleg; Pozdnyakov, Sergey; Price, John; Procureur, Sebastien; Protopopescu, Dan; Raue, Brian; Ripani, Marco; Ritchie, Barry; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Saini, Mukesh; Salgado, Carlos; Schott, Diane; Schumacher, Reinhard; Seder, Erin; Seraydaryan, Heghine; Sharabian, Youri; Smith, Elton; Smith, Gregory; Sober, Daniel; Stepanyan, Stepan; Stoler, Paul; Strakovski, Igor; Strauch, Steffen; Taiuti, Mauro; Tang, Wei; Taylor, Charles; Vernarsky, Brian; Vineyard, Michael; Voutier, Eric; Weinstein, Lawrence; Watts, Daniel; Wood, Michael; Zachariou, Nicholas; Zana, Lorenzo; Zhao, Bo

    2011-04-01T23:59:59.000Z

    The electromagnetic decay $\\Sigma^0(1385) \\to \\Lambda \\gamma$ was studied using the CLAS detector at the Thomas Jefferson National Accelerator Facility. A real photon beam with a maximum energy of 3.8 GeV was incident on a proton target, producing an exclusive final state of $K^+\\Sigma^{*0}$. We report the decay widths ratio $\\Sigma^0(1385) \\to \\Lambda\\gamma$/ $\\Sigma^0(1385) \\to \\Lambda\\pi^0$ = $1.42 \\pm 0.12(\\text{stat})_{-0.07}^{+0.11}(\\text{sys})$%. This ratio is larger than most theoretical predictions by factors ranging from 1.5-3, but is consistent with the only other experimental measurement. From the reported ratio we calculate the partial width and electromagnetic transition magnetic moment for $\\Sigma^0(1385) \\to \\Lambda\\gamma$.

  15. Hybrid Mesons

    E-Print Network [OSTI]

    C. A. Meyer; E. S. Swanson

    2015-03-04T23:59:59.000Z

    A review of the theoretical and experimental status of hybrid hadrons is presented. The states $\\pi_1(1400)$, $\\pi_1(1600)$, and $\\pi_1(2015)$ are thoroughly reviewed, along with experimental results from GAMS, VES, Obelix, COMPASS, KEK, CLEO, Crystal Barrel, CLAS, and BNL. Theoretical lattice results on the gluelump spectrum, adiabatic potentials, heavy and light hybrids, and transition matrix elements are discussed. These are compared with bag, string, flux tube, and constituent gluon models. Strong and electromagnetic decay models are described and compared to lattice gauge theory results. We conclude that while good evidence for the existence of a light isovector exotic meson exists, its confirmation as a hybrid meson awaits discovery of its iso-partners. We also conclude that lattice gauge theory rules out a number of hybrid models and provides a reference to judge the success of others.

  16. Determination of the beam-spin asymmetry of deuteron photodisintegration in the energy region E?=1.1 –2.3 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zachariou, N.; Ilieva, Y.; Ivanov, N. Ya.; Sargsian, M. M.; Avakian, R.; Feldman, G.; Nadel-Turonski, P.

    2015-05-01T23:59:59.000Z

    The beam-spin asymmetry, ?, for the reaction ?d???pn has been measured using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility (JLab) for six photon-energy bins, between 1.1 and 2.3 GeV, and proton angles in the center-of-mass frame, ?c.m., between 25° and 160°. These are the first measurements of beam-spin asymmetries at ?c.m.=90° for photon-beam energies above 1.6 GeV, and the first measurements for angles other than ?c.m.=90°. The angular and energy dependence of ? is expected to aid in the development of QCD-based models to understand the mechanisms of deuteron photodisintegration in the transition regionmore »between hadronic and partonic degrees of freedom, where both effective field theories and perturbative QCD cannot make reliable predictions.« less

  17. Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction ?p ? ?p

    SciTech Connect (OSTI)

    Dey, B. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Meyer, C. A. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Bellis, M. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Williams, M. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Adhikari, K. P. [Old Dominion Univ., Norfolk, VA (United States); Adikaram, D. [Old Dominion Univ., Norfolk, VA (United States); Aghasyan, M. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LFN); Amaryan, M. J. [Old Dominion Univ., Norfolk, VA (United States); Anderson, M. D. [Univ. of Glasgow, Scotland (United Kingdom); Anefalos Pereira, S. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LFN); Ball, J. [Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA), Saclay (France). Inst. de Physique Nuclaeaire; Baltzell, N. A. [Argonne National Lab. (ANL), Argonne, IL (United States); Battaglieri, M. [Istituto Nazionale di Fisica Nucleare (INFN), Genova (Italy); Bedlinskiy, I. [Inst. of Theoretical and Experimental Physics (ITEP), Moscow (Russian Federation); Biselli, A. S. [Fairfield Univ., CT (United States); Bono, J. [Florida International Univ., Miami, FL (United States); Boiarinov, S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Briscoe, W. J. [George Washington Univ., Washington, DC (United States); Brooks, W. K. [Univ. Tecnica Federico Santa Maria, Valparaiso (Chile); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Burkert, V. D. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Carman, D. S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Celentano, A. [Istituto Nazionale di Fisica Nucleare (INFN), Genova (Italy); Chandavar, S. [Ohio Univ., Athens, OH (United States); Colaneri, L. [National Inst. of Nuclear Physics (INFN), Rome (Italy); Cole, P. L. [Idaho State Univ., Pocatello, ID (United States); Contalbrigo, M. [National Inst. of Nuclear Physics (INFN), Ferrara (Italy); Cortes, O. [Idaho State Univ., Pocatello, ID (United States); Crede, V. [Florida State Univ., Tallahassee, FL (United States); D'Angelo, A. [National Inst. of Nuclear Physics (INFN), Rome (Italy); Univ. di Roma, Rome (Italy); Dashyan, N. [Yerevan Physics Inst. (YerPhI) (Armenia); De Vita, R. [Istituto Nazionale di Fisica Nucleare (INFN), Genova (Italy); De Sanctis, E. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LFN); Deur, A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Djalali, C. [Univ. of South Carolina, Columbia, SC (United States); Doughty, D. [Christopher Newport Univ., Newport News, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Dugger, M. [Arizona State Univ., Tempe, AZ (United States); Dupre, R. [Argonne National Lab. (ANL), Argonne, IL (United States); El Alaoui, A. [Argonne National Lab. (ANL), Argonne, IL (United States); El Fassi, L. [Argonne National Lab. (ANL), Argonne, IL (United States); Elouadrhiri, L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Fedotov, G. [Univ. of South Carolina, Columbia, SC (United States); Fegan, S. [Univ. of Glasgow, Scotland (United Kingdom); Fleming, J. A. [Univ. of Edinburgh, Scotland (United Kingdom); Garçon, M. [Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA), Saclay (France). Inst. de Physique Nuclaeaire; Gevorgyan, N. [Yerevan Physics Inst. (YerPhI) (Armenia); Ghandilyan, Y. [Yerevan Physics Inst. (YerPhI) (Armenia); Gilfoyle, G. P. [Univ. of Richmond, VA (United States); Giovanetti, K. L. [James Madison Univ., Harrisonburg, VA (Untied States); Girod, F. X. [Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA), Saclay (France). Inst. de Physique Nuclaeaire; Glazier, D. I. [Univ. of Edinburgh, Scotland (United Kingdom); Goetz, J. T. [Ohio Univ., Athens, OH (United States)

    2014-05-01T23:59:59.000Z

    High-statistics measurements of differential cross sections and spin density matrix elements for the reaction ? p ? ?p have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (?s) from 1.97 to 2.84 GeV, with an extensive coverage in the ? production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the ? natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged- (? ? K?K?) and neutral- (? ? K0SK0L) KK? decay modes of the ?. Further, for the charged mode, we differentiate between the cases where the final K? track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed ? mass resolution. Our final results are reported in 10- and mostly 30-MeV-wide ?s bins for the charged- and the neutral-mode, respectively. Possible effects from K??* channels with pKK? final-states are discussed. These present results constitute the most precise and extensive ? photoproduction measurements to date and in conjunction with the ? photoproduction results recently published by CLAS, will greatly improve our understanding of low energy vector meson photoproduction.

  18. Nuclear physics research at the University of Richmond. Progress report, November 1, 1994--October 31, 1995

    SciTech Connect (OSTI)

    Vineyard, M.F.; Gilfoyle, G.P.; Major, R.W.

    1995-12-31T23:59:59.000Z

    Summarized in this report is the progress achieved during the period from November 1, 1994 to October 31, 1995. The experimental work described in this report is in electromagnetic and heavy-ion nuclear physics. The effort in electromagnetic nuclear physics is in preparation for the research program at the Continuous Electron Beam Accelerator Facility (CEBAF) and is focused on the construction and use of the CEBAF Large Acceptance Spectrometer (CLAS). The heavy-ion experiments were performed at the Argonne National Laboratory ATLAS facility and SUNY, Stony Brook. The physics interests driving these efforts at CEBAF are in the study of the structure, interactions, and nuclear-medium modifications of mesons and baryons. This year, an extension of the experiment to measure the magnetic form factor of the neutron was approved by the CEBAF Program Advisory Committee Nine (PAC9) for beam at 6 GeV. The authors also submitted updates to PAC9 on the experiments to measure inclusive {eta} photoproduction in nuclei and electroproduction of the {Lambda}, {Lambda}*(1520), and f{sub 0}(975). In addition to these experiments, the authors collaborated on a proposal to measure rare radiative decays of the {phi} meson which was also approved by PAC9. Their contributions to the construction of the CLAS include the development of the drift-chamber gas system, drift-chamber software, and controls software. Major has been leading the effort in the construction of the gas system. In the last year, the Hall B gas shed was constructed and the installation of the gas system components built at the University of Richmond has begun. Over the last six years, the efforts in low-energy heavy-ion physics have decreased due to the change in focus to electromagnetic nuclear physics at CEBAF. Most of the heavy-ion work is completed and there are now new experiments planned. Included in this report are two papers resulting from collaborations on heavy-ion experiments.

  19. Study of the Two-pion Photoproduction on the Deuteron

    SciTech Connect (OSTI)

    Graham, Lewis P. [South Carolina U.

    2012-12-01T23:59:59.000Z

    Understanding the structure of baryons in terms of the fundamental interaction of the constituent quarks and gluons is one of the primary challenges in strong interaction physics. This interaction is governed by Quantum Chromodynamics (QCD), which is a theory for understanding the dynamics of strong. QCD displays the asymptotic freedom of hadrons at very short distances and also the confinement of quarks and gluons inside hadrons. However, solutions of this QCD theory in the non-perturbative domain of the interaction are extremely difficult to achieve, mainly because confinement happens on the hadronic scale on which the coupling constant is large and prevents any perturbative approach. Thus leaving us with strategies such as lattice QCD or formulating QCD sum rules to get around this problem. In exclusive hadron production the yN interaction is recognized for being a powerful method for investigating hadrons and the mysteries that still exist within the strong interaction. From reactions with the nucleon, the strong interaction can be investigated through the transition amplitudes to the N and Delta resonances. More specifically, if an electromagnetic interaction is well known then the intermediate resonance states may be evaluated through meson photoproduction. To gain more detailed insight into this interaction, we look to probe the baryon structure of the nucleon and the photo-excited resonance decays through photon scattering off a deuteron producing two pions in the final state. This photoproduction process off the deuteron will be used to investigate known baryon resonances in the two pion channel. The two pion final state will be investigated for unraveling new information into the photo-coupling strengths. We want to explore final state interactions, search for properties of known resonances, and to explore the possibility of seeing missing states that are predicted by quark models but have not yet been found experimentally. Using the CEBAF Large Acceptance Spectrometer (CLAS), the hadronic products are detected in coincidence with the incident scattered photon on a deuterium target. This makes it possible to measure the single differential cross sections and the decay angular distributions for the production of two pion final states. The measured cross sections will contribute significantly to a better understanding of the coupling strengths that govern the baryonic and mesonic resonances which will push the knowledge of the strong interaction to a next level. We use CLAS to study the two pion channel from the eg3 data set, for resonance production, specifically investigating the exclusive reaction of yd --> p pi^+pi^?n, and comparing the relevant cross sections to already existing data sets. The eg3 data set provided an excellent data set for investigating photo-induced baryonic and mesonic resonances. It contains a large photon tagging range from 1.1 to 5.5 GeV in the study of photo-coupling strengths, as well as an available two pion reaction channel for resonant decay study. These measurements provide unique and coherent results from tagged photons over a broad range of energy, and represent the only two pion production data above 5 GeV at this present time. We found that the data produced good comparable single-differentials cross sections to other existing CLAS (gll dataset) two pion differential cross sections, and an excellent comparable total cross section to published (ELSA and ABBHHM) two pion total cross sections.

  20. UCLA Intermediate Energy Nuclear and Particle Physics Research: Final Report

    SciTech Connect (OSTI)

    B.M.K. Nefkens (Principal Investigator, ed.); J. Goetz; A. Lapik; M. Korolija; S. Prakhov; A. Starostin (ed.)

    2011-05-18T23:59:59.000Z

    This project covers the following research: (a) Investigations into the structure of the proton and neutron. This is done by investigating the different resonance states of nucleons with beams of tagged, polarized photons, linearly as well as circularly, incident on polarized hydrogen/deuterium targets and measuring the production of {pi}{sup #25;0}, 2{pi}{sup #25;}0, 3{pi}{sup #25;0}, {eta}#17;, {eta}', {omega}, etc. The principal detector is the Crystal Ball multiphoton spectrometer which has an acceptance of nearly 4#25;. It has been moved to the MAMI accelerator facility of the University of Mainz, Germany. We investigate the conversion of electromagnetic energy into mesonic matter and conversely. (b) We investigate the consequences of applying the "standard" symmetries of isospin, G�parity, charge conjugation, C, P, T, and chirality using rare and forbidden decays of light mesons such as the {eta}#17;,{eta}' and {omega}. We also investigate the consequences of these symmetries being slightly broken symmetries. We do this by studying selected meson decays using the Crystal Ball detector. (c) We determine the mass, or more precisely the mass difference of the three light quarks (which are inputs to Quantum Chromodynamics) by measuring the decay rate of specially selected {eta}#17; and {eta}' decay modes, again we use the Crystal Ball. (d)We have started a new program to search for the 33 missing cascade baryons using the CLAS detector at the Thomas Jefferson Laboratory. Cascade resonances are very special: they have double strangeness and are quite narrow. This implies that they can be discovered by the missing mass technique in photoproduction reactions such as in {gamma}p{yields}{Xi}{sup #4;�}K{sup +}K{sup +}. The cascade program is of particular importance for the upgrade to 12 GeV of the CLAS detector and for design of the Hall D at JLab. (e) Finally, we are getting more involved in a new program to measure the hadronic matter form factor of complex nuclei, in particular the "neutron skin" of {sup 208}Pb, which is of great interest to astroparticle physics for determining the properties of neutron stars. Processes of study are coherent and non�coherent #25;0 photoproduction. The Crystal Ball is uniquely suited for these studies because of the large acceptance, good direction and energy resolution and it is an inclusive detector for the #25;{pi}{sup 0} final state and exclusive for background such as 2#25;{pi}{sup 0}.

  1. First Measurement of Beam-Recoil Observables Cx and Cz in Hyperon Photoproduction

    E-Print Network [OSTI]

    R. Bradford; R. A. Schumacher; CLAS Collaboration

    2006-11-21T23:59:59.000Z

    Spin transfer from circularly polarized real photons to recoiling hyperons has been measured for the reactions $\\vec\\gamma + p \\to K^+ + \\vec\\Lambda$ and $\\vec\\gamma + p \\to K^+ + \\vec\\Sigma^0$. The data were obtained using the CLAS detector at Jefferson Lab for center-of-mass energies $W$ between 1.6 and 2.53 GeV, and for $-0.85<\\cos\\theta_{K^+}^{c.m.}< +0.95$. For the $\\Lambda$, the polarization transfer coefficient along the photon momentum axis, $C_z$, was found to be near unity for a wide range of energy and kaon production angles. The associated transverse polarization coefficient, $C_x$, is smaller than $C_z$ by a roughly constant difference of unity. Most significantly, the {\\it total} $\\Lambda$ polarization vector, including the induced polarization $P$, has magnitude consistent with unity at all measured energies and production angles when the beam is fully polarized. For the $\\Sigma^0$ this simple phenomenology does not hold. All existing hadrodynamic models are in poor agreement with these results.

  2. From hard exclusive meson electroproduction to deeply virtual Compton scattering

    E-Print Network [OSTI]

    Peter Kroll; Hervé Moutarde; Franck Sabatié

    2013-04-23T23:59:59.000Z

    We systematically evaluate observables for hard exclusive electroproduction of real photons and compare them to experiment using a set of Generalized Parton Distributions (GPDs) whose parameters are constrained by Deeply Virtual Meson Production data, nucleon form factors and parton distributions. The Deeply Virtual Compton Scattering amplitudes are calculated to leading-twist accuracy and leading order in QCD perturbation theory while the leptonic tensor is treated exactly, without any approximation. This study constitutes a check of the universality of the GPDs. We summarize all relevant details on the parametrizations of the GPDs and describe its use in the handbag approach of the aforementioned hard scattering processes. We observe a good agreement between predictions and measurements of deeply virtual Compton scattering on a wide kinematic range, including most data from H1, ZEUS, HERMES, Hall A and CLAS collaborations for unpolarized and polarized targets when available. We also give predictions relevant for future experiments at COMPASS and JLab after the 12 GeV upgrade.

  3. Study of few-nucleon systems with the CEBAF large acceptance spectrometer

    SciTech Connect (OSTI)

    Yordanka Ilieva

    2011-05-01T23:59:59.000Z

    The study of few-nucleon systems at intermediate energies is an important aspect of the nuclear-physics program carried out by the CLAS Collaboration at Jefferson Laboratory. Our investigations aim at understanding the nuclear dynamics at short distances, the transition from hadronic to partonic description of nuclei, and how nuclei can be described in the framework of Quantum Chromodynamics. Our data on photodisintegration of 3He and 4He at beam energies from 0.3 GeV to 1.5 GeV strongly favor theoretical calculations that include three-body mechanisms and indicate significant contributions of these mechanisms at large momentum transfer, especially in the range of photon energies from 0.6 GeV to 0.8 GeV. Our investigations of exclusive and inclusive electron scattering off nuclear targets have yielded the determination of the ratio of pp to pn correlated pairs in 3He and of the probabilities of short-range correlations in nuclei. We have studied the transition from hadronic to partonic dynamics in nuclear processes by searching for the onset of scaling of the invariant cross sections of photoinduced reactions on few-nucleon systems. Our data are consistent with scaling at momentum transfer as low as 1 (GeV/c)2

  4. Measurement of cross sections of p(e,e'pi^+)n for near pion threshold and high-lying resonances at high Q^2

    SciTech Connect (OSTI)

    Kijun Park

    2012-04-01T23:59:59.000Z

    During the last decade, remarkable experimental data have been collected in an extensive programs to study the excitation of nucleon resonance (N*) at Jefferson Laboratory through pion electroproduction using polarized electron beam and unpolarized proton target. The CEBAF Large Acceptance Spectrometer (CLAS) is well suited for the study of a broad range of kinematics in the invariant mass W and photon virtuality Q{sup 2} with nearly complete angular coverage for the hadronic decays. Electron scattering allows us to probe the effective degrees of freedom in excited nucleon states from meson-baryon to dressed quarks in terms of varying the distance scale. The study of nucleon structure allows us to understand these effective degrees of freedom. In this proceeding, I present preliminary cross sections for single pion production in mass range of high-lying resonances as well as near the pion threshold. Analysis of N{pi}{sup +} cross sections together with N{pi}{sup 0} and N {pi}{pi} exclusive electroproduction data, will allow us for the first time to determine electrocouplings of several high-lying excited proton states (W {ge} 1.6 GeV) at photon virtualities that correspond to the transition toward the dominance of quark degrees of freedom. I also present preliminary result on the E{sub 0+} multipole near pion threshold at 2.0 GeV{sup 2} {le} Q{sup 2} {le} 4.5 GeV{sup 2} using exclusive N{pi}{sup +} electroproduction data.

  5. First Observation of the {Lambda}(1405) Line Shape in Electroproduction

    SciTech Connect (OSTI)

    Iowa State U.; Carnegie Mellon U.

    2013-10-01T23:59:59.000Z

    We report the first observation of the line shape of the {Lambda}(1405) from electroproduction, and show that it is not a simple Breit-Wigner resonance. Electroproduction of K{sup +}{Lambda}(1405) off the proton was studied by using data from CLAS at Jefferson Lab in the range 1.0

  6. Induced polarization of ?(1116) in kaon electroproduction

    E-Print Network [OSTI]

    M. Gabrielyan; B. A. Raue; D. S. Carman; K. Park; K. P. Adhikari; D. Adikaram; M. J. Amaryan; S. Anefalos Pereira; H. Avakian; J. Ball; N. A. Baltzell; M. Battaglieri; V. Baturin; I. Bedlinskiy; A. S. Biselli; J. Bono; S. Boiarinov; W. J. Briscoe; W. K. Brooks; V. D. Burkert; T. Cao; A. Celentano; S. Chandavar; G. Charles; P. L. Cole; M. Contalbrigo; O. Cortes; V. Crede; A. DAngelo; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; D. Doughty; R. Dupre; L. El Fassi; P. Eugenio; G. Fedotov; S. Fegan; J. A. Fleming; T. A. Forest; B. Garillon; N. Gevorgyan; Y. Ghandilyan; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; E. Golovatch; R. W. Gothe; K. A. Griffioen; M. Guidal; L. Guo; K. Hafidi; H. Hakobyan; M. Hattawy; K. Hicks; D. Ho; M. Holtrop; S. M. Hughes; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; D. Jenkins; H. Jiang; H. S. Jo; K. Joo; D. Keller; M. Khandaker; W. Kim; F. J. Klein; S. Koirala; V. Kubarovsky; S. E. Kuhn; S. V. Kuleshov; P. Lenisa; W. I. Levine; K. Livingston; I. J. D. MacGregor; M. Mayer; B. McKinnon; C. A. Meyer; M. D. Mestayer; M. Mirazita; V. Mokeev; C. I. Moody; H. Moutarde; A Movsisyan; E. Munevar; C. Munoz Camacho; P. Nadel-Turonski; S. Niccolai; G. Niculescu; M. Osipenko; L. L. Pappalardo; R. Paremuzyan; E. Pasyuk; P. Peng; W. Phelps; J. J. Phillips; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; S. Procureur; D. Protopopescu; D. Rimal; M. Ripani; A. Rizzo; F. Sabatie; C. Salgado; D. Schott; R. A. Schumacher; A. Simonyan; G. D. Smith; D. I. Sober; D. Sokhan; S. S. Stepanyan; S. Stepanyan; I. I. Strakovsky; S. Strauch; V. Sytnik; W. Tang; M. Ungaro; A. V. Vlassov; H. Voskanyan; E. Voutier; N. K. Walford; D. P. Watts; X. Wei; L. B. Weinstein; N. Zachariou; L. Zana; J. Zhang

    2014-06-16T23:59:59.000Z

    We have measured the induced polarization of the ${\\Lambda}(1116)$ in the reaction $ep\\rightarrow e'K^+{\\Lambda}$, detecting the scattered $e'$ and $K^+$ in the final state along with the proton from the decay $\\Lambda\\rightarrow p\\pi^-$.The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy $W$ ($1.6\\leq W \\leq 2.7$ GeV) and covered the full range of the kaon production angle at an average momentum transfer $Q^2=1.90$ GeV$^2$.In this experiment a 5.50 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. We have mapped out the $W$ and kaon production angle dependencies of the induced polarization and found striking differences from photoproduction data over most of the kinematic range studied. However, we also found that the induced polarization is essentially $Q^2$ independent in our kinematic domain, suggesting that somewhere below the $Q^2$ covered here there must be a strong $Q^2$ dependence. Along with previously published photo- and electroproduction cross sections and polarization observables, these data are needed for the development of models, such as effective field theories, and as input to coupled-channel analyses that can provide evidence of previously unobserved $s$-channel resonances.

  7. Towards a resolution of the proton form factor problem: new electron and positron scattering data

    E-Print Network [OSTI]

    D. Adikaram; D. Rimal; L. B. Weinstein; B. Raue; P. Khetarpal; R. P. Bennett; J. Arrington; W. K. Brooks; K. P. Adhikari; A. V. Afanasev; M. J. Amaryan; M. D. Anderson; J. Ball; M. Battaglieri; I. Bedlinskiy; A. S. Biselli; J. Bono; S. Boiarinov; W. J. Briscoe; V. D. Burkert; D. S. Carman; A. Celentano; S. Chandavar; G. Charles; L. Colaneri; P. L. Cole; M. Contalbrigo; A. D'Angelo; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; G. E. Dodge; R. Dupre; H. Egiyan; A. El Alaoui; L. El Fassi; P. Eugenio; G. Fedotov; S. Fegan; A. Filippi; J. A. Fleming; A. Fradi; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; W. Gohn; E. Golovatch; R. W. Gothe; K. A. Griffioen; M. Guidal; L. Guo; K. Hafidi; H. Hakobyan; N. Harrison; M. Hattawy; K. Hicks; M. Holtrop; S. M. Hughes; C. E. Hyde; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; D. Jenkins; H. Jiang; K. Joo; S. Joosten; M. Khandaker; W. Kim; A. Klein; F. J. Klein; S. Koirala; V. Kubarovsky; S. E. Kuhn; H. Y. Lu; I . J . D. MacGregor; N. Markov; M. Mayer; B. McKinnon; M. D. Mestayer; C. A. Meyer; M. Mirazita; V. Mokeev; R. A. Montgomery; C. I. Moody; H. Moutarde; A Movsisyan; C. Munoz Camacho; P. Nadel-Turonski; S. Niccolai; G. Niculescu; M. Osipenko; A. I. Ostrovidov; K. Park; E. Pasyuk; S. Pisano; O. Pogorelko; S. Procureur; Y. Prok; D. Protopopescu; A. J. R. Puckett; M. Ripani; A. Rizzo; G. Rosner; P. Rossi; F. Sabatié; D. Schott; R. A. Schumacher; Y. G. Sharabian; A. Simonyan; I. Skorodumina; E. S. Smith; G. D. Smith; D. I. Sober; N. Sparveris; S. Stepanyan; S. Strauch; V. Sytnik; M. Taiuti; Ye Tian; A. Trivedi; M. Ungaro; H. Voskanyan; E. Voutier; N. K. Walford; D. P. Watts; X. Wei; M. H. Wood; N. Zachariou; L. Zana; J. Zhang; Z. W. Zhao; I. Zonta; The CLAS Collaboration

    2014-11-25T23:59:59.000Z

    There is a significant discrepancy between the values of the proton electric form factor, $G_E^p$, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of $G_E^p$ from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization ($\\varepsilon$) and momentum transfer ($Q^2$) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing $\\varepsilon$ at $Q^2 = 1.45 \\text{ GeV}^2$. This measurement is consistent with the size of the form factor discrepancy at $Q^2\\approx 1.75$ GeV$^2$ and with hadronic calculations including nucleon and $\\Delta$ intermediate states, which have been shown to resolve the discrepancy up to $2-3$ GeV$^2$.

  8. Measurement of Exclusive $?^0$ Electroproduction Structure Functions and their Relationship to Transversity GPDs

    E-Print Network [OSTI]

    CLAS Collaboration; I. Bedlinskiy; V. Kubarovsky; S. Niccolai; P. Stoler; K. P. Adhikari; M. Aghasyan; M. J. Amaryan; M. Anghinolfi; H. Avakian; H. Baghdasaryan; J. Ball; N. A. Baltzell; M. Battaglieri; R. P. Bennett; A. S. Biselli; C. Bookwalter; S. Boiarinov; W. J. Briscoe; W. K. Brooks; V. D. Burkert; D. S. Carman; A. Celentano; S. Chandavar; G. Charles; M. Contalbrigo; V. Crede; A. D'Angelo; A. Daniel; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; D. Doughty; R. Dupre; H. Egiyan; A. El Alaoui; L. El Fassi; L. Elouadrhiri; P. Eugenio; G. Fedotov; S. Fegan; J. A. Fleming; T. A. Forest; M. Garçon; N. Gevorgyan; K. L. Giovanetti; F. X. Girod; W. Gohn; R. W. Gothe; L. Graham; K. A. Griffioen; B. Guegan; M. Guidal; L. Guo; K. Hafidi; H. Hakobyan; C. Hanretty; D. Heddle; K. Hicks; M. Holtrop; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; E. L. Isupov; H. S. Jo; K. Joo; D. Keller; M. Khandaker; P. Khetarpal; A. Kim; W. Kim; F. J. Klein; S. Koirala; A. Kubarovsky; S. E. Kuhn; S. V. Kuleshov; N. D. Kvaltine; K. Livingston; H. Y. Lu; I. J. D. MacGregor; Y. Mao; N. Markov; D. Martinez; M. Mayer; B. McKinnon; C. A. Meyer; T. Mineeva; M. Mirazita; V. Mokeev; H. Moutarde; E. Munevar; C. Munoz Camacho; P. Nadel-Turonski; G. Niculescu; I. Niculescu; M. Osipenko; A. I. Ostrovidov; L. L. Pappalardo; R. Paremuzyan; K. Park; S. Park; E. Pasyuk; S. Anefalos Pereira; E. Phelps; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; S. Procureur; Y. Prok; D. Protopopescu; A. J. R. Puckett; B. A. Raue; G. Ricco; D. Rimal; M. Ripani; G. Rosner; P. Rossi; F. Sabatié; M. S. Saini; C. Salgado; N. Saylor; D. Schott; R. A. Schumacher; E. Seder; H. Seraydaryan; Y. G. Sharabian; G. D. Smith; D. I. Sober; D. Sokhan; S. S. Stepanyan; S. Stepanyan; S. Strauch; M. Taiuti; W. Tang; C. E. Taylor; Ye Tian; S. Tkachenko; M. Ungaro; M. F. Vineyard; A. Vlassov; H. Voskanyan; E. Voutier; N. K. Walford; D. P. Watts; L. B. Weinstein; D. P. Weygand; M. H. Wood; N. Zachariou; J. Zhang; Z. W. Zhao; I. Zonta

    2012-09-24T23:59:59.000Z

    Exclusive $\\pi^0$ electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in $Q^2$, $x_B$, $t$, and $\\phi_\\pi$, in the $Q^2$ range from 1.0 to 4.6 GeV$^2$,\\ $-t$ up to 2 GeV$^2$, and $x_B$ from 0.1 to 0.58. Structure functions $\\sigma_T +\\epsilon \\sigma_L, \\sigma_{TT}$ and $\\sigma_{LT}$ were extracted as functions of $t$ for each of 17 combinations of $Q^2$ and $x_B$. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates $\\sigma_T +\\epsilon \\sigma_L$ and fails to account for $\\sigma_{TT}$ and $\\sigma_{LT}$, while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity flip and helicity non-flip processes. The results confirm that exclusive $\\pi^0$ electroproduction offers direct experimental access to the transversity GPDs.

  9. Beam-spin Asymmetries from Semi-inclusive Pion Electroproduction

    SciTech Connect (OSTI)

    Gohn, Wesley P. [University of Connecticut, Storrs, CT (United States); Avakian, Harut A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Joo, Kyungseon [University of Connecticut, Storrs, CT (United States); Ungaro, Maurizio [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2014-04-01T23:59:59.000Z

    We have measured the moment A{sup sin{phi}}{sub LU} corresponding to the polarized electron beam-spin asymmetry in SIDIS. A{sup sin{phi}}{sub LU} is a twist-3 quantity providing information about quark-gluon correlations. Data were taken with the CLAS Spectrometer at Jefferson Lab using a 5.498 GeV longitudinally polarized electron beam and an unpolarized liquid hydrogen target. All three pion channels (pi{sup +}, pi{sup 0} and pi{sup -}) were measured simultaneously over a large range of kinematics within the virtuality range Q{sup 2} ~ 1.0-4.5 GeV{sup 2}. The observable was measured with good statistical precision over a large range of z, P{sub T}, x{sub B}, and Q{sup 2}, which permits comparison with several reaction models. The discussed measurements provide an upgrade in statistics over previous measurements, and serve as the first evidence for the negative sign of the {pi}{sup -} sin{phi} Moment.

  10. Differential cross sections for gamma + p --> K^+ + Y for Lambda and Sigma^0 hyperons

    SciTech Connect (OSTI)

    R. Bradford; R.A. Schumacher; J.W.C. McNabb; L. Todor; et. Al.

    2005-09-29T23:59:59.000Z

    High-statistics cross sections for the reactions {gamma} + p {yields} K{sup +} + {Lambda} and {gamma} + p {yields} K{sup +} + {Sigma}{sup 0} have been measured using CLAS at Jefferson Lab for center-of-mass energies W between 1.6 and 2.53 GeV, and for -0.85 < cos {theta}{sub K{sup +}}{sup c.m.} < +0.95. In the K{sup +}{Lambda} channel we confirm a resonance-like structure near W=1.9 GeV at backward kaon angles. The position and width of this structure change with angle, indicating that more than one resonance is likely playing a role. The K{sup +} {Lambda} channel at forward angles and all energies is well described by a t-channel scaling characteristic of Regge exchange, while the same scaling applied to the K{sup +} {Sigma}{sup 0} channel is less successful. Several existing theoretical models are compared to the data, but none provide a good representation of the results.

  11. Light Vector Mesons in the Nuclear Medium

    E-Print Network [OSTI]

    M. H. Wood; R. Nasseripour; D. P. Weygand; C. Djalali; C. Tur; U. Mosel; P. Muehlich; CLAS Collaboration

    2008-03-04T23:59:59.000Z

    The light vector mesons ($\\rho$, $\\omega$, and $\\phi$) were produced in deuterium, carbon, titanium, and iron targets in a search for possible in-medium modifications to the properties of the $\\rho$ meson at normal nuclear densities and zero temperature. The vector mesons were detected with the CEBAF Large Acceptance Spectrometer (CLAS) via their decays to $e^{+}e^{-}$. The rare leptonic decay was chosen to reduce final-state interactions. A combinatorial background was subtracted from the invariant mass spectra using a well-established event-mixing technique. The $\\rho$ meson mass spectrum was extracted after the $\\omega$ and $\\phi$ signals were removed in a nearly model-independent way. Comparisons were made between the $\\rho$ mass spectra from the heavy targets ($A > 2$) with the mass spectrum extracted from the deuterium target. With respect to the $\\rho$-meson mass, we obtain a small shift compatible with zero. Also, we measure widths consistent with standard nuclear many-body effects such as collisional broadening and Fermi motion.

  12. Delta Electroproduction in 12-C

    SciTech Connect (OSTI)

    Steven McLauchlan

    2003-01-31T23:59:59.000Z

    The Delta-nucleus potential is a crucial element in the understanding of the nuclear system. Previous electroexcitation measurements in the delta region reported a Q2 dependence of the delta mass indicating that this potential is dependent on the momentum of the delta. Such a dependence is not observed for protons and neutrons in the nuclear medium. This thesis presents the experimental study of the electroexcitation of the delta resonance in 12C, performed using the high energy electron beam at the Thomas Jefferson National Accelerator Facility, and the near 4(pie) acceptance detector CLAS that enables the detection of the full reaction final state. Inclusive, semi inclusive, and exclusive cross sections were measured with an incident electron beam energy of 1.162GeV over the Q2 range 0.175-0.475 (GeV/c)2. A Q2 dependence of the delta mass was only observed in the exclusive measurements indicating that the delta-nucleus potential is affected by the momentum of the delta.

  13. Polarization Observables for K{sup +}{Lambda} and K{sup +}{Sigma}{sup 0} Photoproduction form Polarized Protons

    SciTech Connect (OSTI)

    Walford, Natalie K. [Catholic University of America, Washington, DC (United States); Klein, Franz J.W. [Catholic University of America, Washington, DC (United States)

    2014-01-01T23:59:59.000Z

    The search for undiscovered excited states of the nucleon continues to be a focus of experiments at Jefferson Lab. Recent LQCD calculations have confirmed long-standing quark-model predictions of many more states than have so far been identified. A large effort for the N* program has been launched using the CLAS detector to provide the database that will allow nearly model-independent partial wave analyses to be carried out in the search for such states. Polarization observables play a crucial role in this effort, as they are essential in disentangling overlapping resonant and non-resonant amplitudes. In 2010, double-polarization data were taken at JLab using circularly polarized photons incident on a transversely polarized frozen-spin butanol target. Our current analysis yields preliminary data of the T and F asymmetries of the K{sup +}{Lambda} and K{sup +}{Sigma}{sup 0} final states, which are compared to predictions of recent multipole analyses. This work is the first of its kind and will significantly broaden the world database for these reactions.

  14. Exclusive processes at JLab at 6 GeV

    SciTech Connect (OSTI)

    Kim, Andrey [University of Connecticut, JLAB

    2015-01-01T23:59:59.000Z

    Deeply virtual exclusive reactions provide a unique opportunity to probe the complex internal structure of the nucleon. They allow to access information about the correlations between parton transverse spatial and longitudinal momentum distributions from experimental observables. Dedicated experiments to study Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP) have been carried out at Jefferson Lab using continuous electron beam with energies up to 6 GeV. Unpolarized cross sections, beam, target and double spin asymmetries have been measured for DVCS as well as for ?0 exclusive electroproduction. The data from Hall B provide a wide kinematic coverage with Q2=1-4.5 GeV2, xB=0.1-0.5, and ?t up to 2 GeV2. Hall A data have limited kinematic range partially overlapping with Hall B kinematics but provide a high accuracy measurements. Scaling tests of the DVCS cross sections provide solid evidence of twist-2 dominance, which makes chiral-even GPDs accessible even at modest Q2. We will discuss the interpretation of these data in terms of Generalized Parton Distributions (GPDs) model. Successful description of the recent CLAS ?0 exclusive production data within the framework of the GPD-based model provides a unique opportunity to access the chiral-odd GPDs.

  15. Induced polarization of Lambda(1116) in kaon electroproduction

    SciTech Connect (OSTI)

    Gabrielyan, M.; Raue, B.A.; Carman, D.S.; Park, K.; Adhikari, K.P.; Adikaram, D.; Amaryan, M.J.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Baltzell, N.A.; Battaglieri, M.; Baturin, V.; Bedlinskiy, I.; Biselli, A.S.; Bono, J.; Boiarinov, S.; Briscoe, W.J.; Brooks, W.K.; Burkert, V.D.; Cao, T.; Celentano, A.; Chandavar, S.; Charles, G.; Cole, P.L.; Contalbrigo, M.; Cortes, O.; Crede, V.; D’Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; ElFassi, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fleming, J.A.; Forest, T.A.; Garillon, B.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G.P.; Giovanetti, K.L.; Girod, F.X.; Goetz, J.T.; Golovatch, E.; Gothe, R.W.; Griffioen, K.A.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hattawy, M.; Hicks, K.; Ho, D.; Holtrop, M.; Hughes, S.M.; Ilieva, Y.; Ireland, D.G.; Ishkhanov, B.S.; Jenkins, D.; Jiang, H.; Jo, H.S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, W.; Klein, F.J.; Koirala, S.; Kubarovsky, V.; Kuhn, S.E.; Kuleshov, S.V.; Lenisa, P.; Levine, W.I.; Livingston, K.; MacGregor, I.J.D.; Mayer, M.; McKinnon, B.; Meyer, C.A.; Mestayer, M.D.; Mirazita, M.; Mokeev, V.; Moody, C.I.; Moutarde, H.; Movsisyan, A; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Pappalardo, L.L.; Paremuzyan, R.; Pasyuk, E.; Peng, P.; Phelps, W.; Phillips, J.J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J.W.; Procureur, S.; Protopopescu, D.; Rimal, D.; Ripani, M.; Rizzo, A.; Sabatie, F.; Salgado, C.; Schott, D.; Schumacher, R.A.; Simonyan, A.; Smith, G.D.; Sober, D.I.; Sokhan, D.; Stepanyan, S.S.; Stepanyan, S.; Strakovsky, I.I.; Strauch, S.; Sytnik, V.; Tang, W.; Ungaro, M.; Vlassov, A.V.; Voskanyan, H.; Voutier, E.; Walford, N.K.; Watts, D.P.; Wei, X.; Weinstein, L.B.; Zachariou, N.; Zana, L.; Zhang, J.

    2014-09-01T23:59:59.000Z

    We have measured the induced polarization of the ?(1116) in the reaction ep?e?K+?, detecting the scattered e? and K+ in the final state along with the proton from the decay ??p??.The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy W (1.6?W?2.7 GeV) and covered the full range of the kaon production angle at an average momentum transfer Q2=1.90 GeV2.In this experiment a 5.50 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. We have mapped out the W and kaon production angle dependencies of the induced polarization and found striking differences from photoproduction data over most of the kinematic range studied. However, we also found that the induced polarization is essentially Q2 independent in our kinematic domain, suggesting that somewhere below the Q2 covered here there must be a strong Q2 dependence. Along with previously published photo- and electroproduction cross sections and polarization observables, these data are needed for the development of models, such as effective field theories, and as input to coupled-channel analyses that can provide evidence of previously unobserved s-channel resonances.

  16. Towards a Resolution of the Proton Form Factor Problem: New Electron and Positron Scattering Data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adikaram, D; Rimal, D; Weinstein, L B.; Raue, B; Khetarpal, P; Bennett, R; Arrington, J; Brooks, W; Adhikari, K; Afanasev, A; et al

    2015-02-01T23:59:59.000Z

    There is a significant discrepancy between the values of the proton electric form factor, GpE, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GpE from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (epsilon) and momentummore »transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ? at Q2=1.45 GeV2. This measurement is consistent with the size of the form factor discrepancy at Q2?1.75 GeV2 and with hadronic calculations including nucleon and Delta intermediate states, which have been shown to resolve the discrepancy up to 2-3 GeV2.« less

  17. Neutron observables from inclusive lepton scattering on nuclei

    SciTech Connect (OSTI)

    Rinat, A. S.; Taragin, M. F. [Weizmann Institute of Science, Department of Particle Physics, Rehovot 76100 (Israel)

    2010-07-15T23:59:59.000Z

    We analyze new data from Thomas Jefferson National Accelerator Facility (JLab) for inclusive electron scattering on various targets. Computed and measured total inclusive cross sections in the range 0.3 < or approx. x < or approx. 0.95 show reasonable agreement on a logarithmic scale for all targets. However, closer inspection of the quasielastic components reveals serious discrepancies. European Muon Collaboration (EMC) ratios with conceivably smaller systematic errors fare the same. As a consequence, the new data do not enable the extraction of the magnetic form factor G{sub M}{sup n} and the structure function F{sub 2}{sup n} of the neutron, although the application of exactly the same analysis to older data had been successful. We incorporate in the above analysis older CLAS Collaboration data on F{sub 2}{sup 2H}. Removal of some scattered points from those makes it appear possible to obtain the desired neutron information. We compare our results with others from alternative sources. Special attention is paid to the A=3 isodoublet cross sections and EMC ratios. Present data exist only for {sup 3}He, but the available input in combination with charge symmetry enables computations for {sup 3}H. Their average is the computed isoscalar part and is compared with the empirical modification of {sup 3}He EMC ratios toward a fictitious A=3 isosinglet.

  18. Measurement of the Nucleon Structure Function F2 in the Nuclear Medium and Evaluation of its Moments

    SciTech Connect (OSTI)

    M. Osipenko

    2010-11-01T23:59:59.000Z

    We report on the measurement of inclusive electron scattering off a carbon target performed with CLAS at Jefferson Laboratory. A combination of three different beam energies 1.161, 2.261 and 4.461 GeV allowed us to reach an invariant mass of the final-state hadronic system W~2.4 GeV with four-momentum transfers Q2 ranging from 0.2 to 5 GeV2. These data, together with previous measurements of the inclusive electron scattering off proton and deuteron, which cover a similar continuous two-dimensional region of Q2 and Bjorken variable x, permit the study of nuclear modifications of the nucleon structure. By using these, as well as other world data, we evaluated the F2 structure function and its moments. Using an OPE-based twist expansion, we studied the Q2-evolution of the moments, obtaining a separation of the leading-twist and the total higher-twist terms. The carbon-to-deuteron ratio of the leading-twist contributions to the F2 moments exhibits the well known EMC effect, compatible with that discovered previously in x-space. The total higher-twist term in the carbon nucleus appears, although with large systematic uncertainites, to be smaller with respect to the deuteron case for n<7, suggesting partial parton deconfinement in nuclear matter. We speculate that the spatial extension of the nucleon is changed when it is immersed in the nuclear medium.

  19. Towards a Resolution of the Proton Form Factor Problem: New Electron and Positron Scattering Data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adikaram, D.; Rimal, D.; Weinstein, L B.; Raue, B.; Khetarpal, P.; Bennett, R; Arrington, J.; Brooks, W; Adhikari, K; Afanasev, A; Amaryan, M; Anderson, M; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Battaglieri, M.; Bedlinskiy, I.; Biselli, A; Bono, J.; Boiarinov, S.; Briscoe, W; Burkert, V; Carman, D; Careccia, S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P; Contalbrigo, M.; Crede, V.; D'Angelo, A; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dodge, G; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J; Fradi, A.; Garillon, B.; Gilfoyle, G; Giovanetti, K; Girod, F; Goetz, J; Gohn, W.; Golovatch, E.; Gothe, R; Griffioen, K; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hicks, K.; Holtrop, M.; Hughes, S; Hyde, C E; Ilieva, Y.; Ireland, D; Ishkhanov, B; Jenkins, D.; Jiang, H.; Jo, H; Joo, K.; Joosten, S.; Kalantarians, N.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F; Koirala, S.; Kubarovsky, V.; Kuhn, S; Livingston, K.; Lu, H; MacGregor, I; Markov, N.; Mattione, P.; Mayer, M.; McKinnon, B.; Mestayer, M; Meyer, C; Mirazita, M.; Mokeev, V.; Montgomery, R; Moody, C; Moutarde, H.; Movsisyan, A.; Camacho, C. Munoz; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Ostrovidov, A; Park, K.; Pasyuk, E.; Pisano, S.; Pogorelko, O.; Price, J; Procureur, S.; Prok, Y.; Protopopescu, D.; Puckett, A; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabati, F; Salgado, C.; Schott, D.; Schumacher, R; Seder, E.; Sharabian, Y; Simonyan, A.; Skorodumina, I.; Smith, E; Smith, G; Sober, D; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tian, Ye; Trivedi, A.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N; Watts, D; Wei, X.; Wood, M; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z; Zonta, I.

    2015-02-10T23:59:59.000Z

    There is a significant discrepancy between the values of the proton electric form factor, GpE, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GpE from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (epsilon) and momentum transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ? at Q2=1.45 GeV2. This measurement is consistent with the size of the form factor discrepancy at Q2?1.75 GeV2 and with hadronic calculations including nucleon and Delta intermediate states, which have been shown to resolve the discrepancy up to 2-3 GeV2.

  20. Search for Resonances in the Photoproduction of Proton-Antiproton Pairs

    SciTech Connect (OSTI)

    Burnham Stokes

    2006-06-30T23:59:59.000Z

    Results are reported on the reaction {gamma}p {yields} p{bar p}p with beam energy in the range 4.8-5.5 GeV. The data were collected at the Thomas Jefferson National Accelerator Facility in CLAS experiment E01-017(G6C). The focus of this study is an understanding of the mechanisms of photoproduction of proton-antiproton pairs, and to search for intermediate resonances, both narrow and broad, which decay to p{bar p}. The total measured cross section in the photon energy range 4.8-5.5 GeV is {sigma} = 33 {+-} 2 nb. Measurement of the cross section as a function of energy is provided. An upper limit on the production of a narrow resonance state previously observed with a mass of 2.02 GeV/c{sup 2} is placed at 0.35 nb. No intermediate resonance states were observed. Meson exchange production appears to dominate the production of the proton-antiproton pairs.

  1. Medium energy nuclear physics research. Progress report for the period June 1, 1992 through May 31, 1993

    SciTech Connect (OSTI)

    Peterson, G.A.; Dubach, J.F.; Hicks, R.S.; Miskimen, R.A.

    1993-06-01T23:59:59.000Z

    The University of Massachusetts (UMass) Nuclear Physics Program continues to concentrate upon the use of the electromagnetic interaction in a joint experimental and theoretical approach to the study of nucleon and nuclear properties. During the past year the activities of the group involved data analysis, design and construction of equipment, planning for new experiments, completion of papers and review articles for publication, writing of proposals for experiments, but very little actual data acquisition. Section II.A. described experiments at Bates Linear Accelerator Center. They include the following: electrodisintegration of deuteron; measurement of the elastic magnetic form factor of {sup 3}He; coincidence measurement of the D(e,e{prime}p) cross section; transverse form factors of {sup 117}Sn; ground state magnetization density of {sup 89}Y; and measurement of the 5th structure function in deuterium and {sup 12}C. Section II.B. includes the following experiments at Stanford Linear Accelerator Center: deuteron threshold electrodisintegration; separation of charge and magnetic form factors of the neutron and proton; measurement of the X-, Q{sup 2}, and A-dependence of R = {sigma}{sub L}/{sigma}{sub T}; and analysis of 14.5 GeV electrons and positions scattered from gases in the PEP Storage Ring. Section III.C. includes the following experiments at NIKHEF and Lund: complementary studies of single-nucleon knockout and single-nucleon wave functions using electromagnetic interactions and single-particle densities of sd-shell nuclei. Section II.D. discusses preparations for future work at CEBAF: electronics for the CLAS region 1 drift chamber Section III. includes theoretical work on parity-violating electron scattering and nuclear structure.

  2. Search for the $?^+$ pentaquark in the reactions $?p \\to \\bar K^0K^+n$ and $?p \\to \\bar K^0K^0p$

    E-Print Network [OSTI]

    R. De Vita; M. Battaglieri; V. Kubarovsky; N. A. Baltzell; M. Bellis; J. Goett; L. Guo; G. S. Mutchler; P. Stoler; M. Ungaro; D. P. Weygand; the CLAS Collaboration

    2006-06-27T23:59:59.000Z

    The exclusive reactions $\\gamma p \\to \\bar K^0 K^+ n$ and $\\gamma p \\to \\bar K^0 K^0 p$ have been studied in the photon energy range 1.6--3.8 GeV, searching for evidence of the exotic baryon $\\Theta^+(1540)$ in the decays $\\Theta^+\\to nK^+$ and $\\Theta^+\\to p K^0$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The integrated luminosity was about 70 pb$^{-1}$. The reactions have been isolated by detecting the $K^+$ and proton directly, the neutral kaon via its decay to $K_S \\to \\pi^+ \\pi^-$ and the neutron or neutral kaon via the missing mass technique. The mass and width of known hyperons such as $\\Sigma^+$, $\\Sigma^-$ and $\\Lambda(1116)$ were used as a check of the mass determination accuracy and experimental resolution. Approximately 100,000 $\\Lambda^*(1520)$'s and 150,000 $\\phi$'s were observed in the $\\bar K^0 K^+ n$ and $\\bar K^0 K^0 p$ final state respectively. No evidence for the $\\Theta^+$ pentaquark was found in the $nK^+$ or $pK_S$ invariant mass spectra. Upper limits were set on the production cross section of the reaction $\\gamma p \\to \\Theta^+ \\bar K^0$ as functions of center-of-mass angle, $nK^+$ and $pK_S$ masses. Combining the results of the two reactions, the 95% C.L. upper limit on the total cross section for a resonance peaked at 1540 MeV was found to be 0.7 nb. Within most of the available theoretical models, this corresponds to an upper limit on the $\\Theta^+$ width, $\\Gamma_{\\Theta^{+}}$, ranging between 0.01 and 7 MeV.

  3. Demonstration of a novel technique to measure two-photon exchange effects in elastic $e^\\pm p$ scattering

    E-Print Network [OSTI]

    M. Moteabbed; M. Niroula; B. A. Raue; L. B. Weinstein; D. Adikaram; J. Arrington; W. K. Brooks; J. Lachniet; Dipak Rimal; M. Ungaro; K. P. Adhikari; M. Aghasyan; M. J. Amaryan; S. Anefalos Pereira; H. Avakian; J. Ball; N. A. Baltzell; M. Battaglieri; V. Batourine; I. Bedlinskiy; R. P. Bennett; A. S. Biselli; J. Bono; S. Boiarinov; W. J. Briscoe; V. D. Burkert; D. S. Carman; A. Celentano; S. Chandavar; P. L. Cole; P. Collins; M. Contalbrigo; O. Cortes; V. Crede; A. D'Angelo; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; D. Doughty; R. Dupre; H. Egiyan; L. El Fassi; P. Eugenio; G. Fedotov; S. Fegan; R. Fersch; J. A. Fleming; N. Gevorgyan; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; W. Gohn; E. Golovatch; R. W. Gothe; K. A. Griffioen; M. Guidal; N. Guler; L. Guo; K. Hafidi; H. Hakobyan; C. Hanretty; N. Harrison; D. Heddle; K. Hicks; D. Ho; M. Holtrop; C. E. Hyde; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; E. L. Isupov; H. S. Jo; K. Joo; D. Keller; M. Khandaker; A. Kim; F. J. Klein; S. Koirala; A. Kubarovsky; V. Kubarovsky; S. E. Kuhn; S. V. Kuleshov; S. Lewis; H. Y. Lu; M. MacCormick; I . J . D. MacGregor; D. Martinez; M. Mayer; B. McKinnon; T. Mineeva; M. Mirazita; V. Mokeev; R. A. Montgomery; K. Moriya; H. Moutarde; E. Munevar; C. Munoz Camacho; P. Nadel-Turonski; R. Nasseripour; S. Niccolai; G. Niculescu; I. Niculescu; M. Osipenko; A. I. Ostrovidov; L. L. Pappalardo; R. Paremuzyan; K. Park; S. Park; E. Phelps; J. J. Phillips; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; S. Procureur; D. Protopopescu; A. J. R. Puckett; M. Ripani; G. Rosner; P. Rossi; F. Sabatié; M. S. Saini; C. Salgado; D. Schott; R. A. Schumacher; E. Seder; H. Seraydaryan; Y. G. Sharabian; E. S. Smith; G. D. Smith; D. I. Sober; D. Sokhan; S. Stepanyan; S. Strauch; W. Tang; C. E. Taylor; Ye Tian; S. Tkachenko; H. Voskanyan; E. Voutier; N. K. Walford; M. H. Wood; N. Zachariou; L. Zana; J. Zhang; Z. W. Zhao; I. Zonta

    2013-07-10T23:59:59.000Z

    The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. We present the results of a new experimental technique for making direct $e^\\pm p$ comparisons, which has the potential to make precise measurements over a broad range in $Q^2$ and scattering angles. We use the Jefferson Lab electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of $Q^2$ and scattering angle. Nonetheless, this measurement yields a data sample for $e^\\pm p$ with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. The final ratio of positron to electron scattering: $R=1.027\\pm0.005\\pm0.05$ for $=0.206$ GeV$^2$ and $0.830\\leq \\epsilon\\leq 0.943$.

  4. Electron Scattering From High-Momentum Neutrons in Deuterium

    SciTech Connect (OSTI)

    A.V. Klimenko; S.E. Kuhn

    2005-10-12T23:59:59.000Z

    We report results from an experiment measuring the semi-inclusive reaction D(e,e'p{sub s}) where the proton p{sub s} is moving at a large angle relative to the momentum transfer. If we assume that the proton was a spectator to the reaction taking place on the neutron in deuterium, the initial state of that neutron can be inferred. This method, known as spectator tagging, can be used to study electron scattering from high-momentum (off-shell) neutrons in deuterium. The data were taken with a 5.765 GeV electron beam on a deuterium target in Jefferson Laboratory's Hall B, using the CLAS detector. A reduced cross section was extracted for different values of final-state missing mass W*, backward proton momentum {rvec p}{sub s} and momentum transfer Q{sup 2}. The data are compared to a simple PWIA spectator model. A strong enhancement in the data observed at transverse kinematics is not reproduced by the PWIA model. This enhancement can likely be associated with the contribution of final state interactions (FSI) that were not incorporated into the model. A ''bound neutron structure function'' F{sub 2n}{sup eff} was extracted as a function of W* and the scaling variable x* at extreme backward kinematics, where effects of FSI appear to be smaller. For p{sub s} > 400 MeV/c, where the neutron is far off-shell, the model overestimates the value of F{sub 2n}{sup eff} in the region of x* between 0.25 and 0.6. A modification of the bound neutron structure function is one of possible effects that can cause the observed deviation.

  5. Electron Scattering From High-Momentum Neutrons in Deuterium

    E-Print Network [OSTI]

    A. V. Klimenko; S. E. Kuhn; for the CLAS collaboration

    2005-10-12T23:59:59.000Z

    We report results from an experiment measuring the semi-inclusive reaction $d(e,e'p_s)$ where the proton $p_s$ is moving at a large angle relative to the momentum transfer. If we assume that the proton was a spectator to the reaction taking place on the neutron in deuterium, the initial state of that neutron can be inferred. This method, known as spectator tagging, can be used to study electron scattering from high-momentum (off-shell) neutrons in deuterium. The data were taken with a 5.765 GeV electron beam on a deuterium target in Jefferson Laboratory's Hall B, using the CLAS detector. A reduced cross section was extracted for different values of final-state missing mass $W^{*}$, backward proton momentum $\\vec{p}_{s}$ and momentum transfer $Q^{2}$. The data are compared to a simple PWIA spectator model. A strong enhancement in the data observed at transverse kinematics is not reproduced by the PWIA model. This enhancement can likely be associated with the contribution of final state interactions (FSI) that were not incorporated into the model. A ``bound neutron structure function'' $F_{2n}^{eff}$ was extracted as a function of $W^{*}$ and the scaling variable $x^{*}$ at extreme backward kinematics, where effects of FSI appear to be smaller. For $p_{s}>400$ MeV/c, where the neutron is far off-shell, the model overestimates the value of $F_{2n}^{eff}$ in the region of $x^{*}$ between 0.25 and 0.6. A modification of the bound neutron structure function is one of possible effects that can cause the observed deviation.

  6. Determination of the Azimuthal Asymmetry of Deuteron Photodisintegration in the Energy Region E{sub {gamma}} = 1.1 - 2.3 GeV

    SciTech Connect (OSTI)

    Nicholas Zachariou

    2012-05-20T23:59:59.000Z

    Deuteron photodisintegration is a benchmark process for the investigation of the role of quarks and gluons in nuclei. Existing theoretical models of this process describe the available cross sections with the same degree of success. Therefore, spin-dependent observables are crucial for a better understanding of the underlying dynamical mechanisms. However, data on the induced polarization (P{sub y}), along with the polarization transfers (C{sub x'} and C{sub z'} ), have been shown to be insensitive to differences between theoretical models. On the other hand, the beam-spin asymmetry {Sigma} is predicted to have a large sensitivity and is expected to help in identifying the energy at which the transition from the hadronic to the quark-gluon picture of the deuteron takes place. Here, the work done to determine the experimental values of the beam-spin asymmetry in deuteron photodisintegration for photon energies between 1.1 ? 2.3 GeV is presented. The data were taken with the CLAS at the Thomas Jefferson National Accelerator Facility during the g13 experiment. Photons with linear polarization of ~80% were produced using the coherent bremsstrahlung facility in Hall B. The work done by the author to calibrate a specific detector system, select deuteron photodisintegration events, study the degree of photon polarization, and finally determine the azimuthal asymmetry and any systematic uncertainties associate with it, is comprehensively explained. This work shows that the collected data provide the kinematic coverage and statistics to test the available QCD-based models. The results of this study show that the available theoretical models in their current state do not adequately predict the azimuthal asymmetry in the energy region 1.1 ? 2.3 GeV.

  7. Short-Course Accelerated Radiotherapy in Palliative Treatment of Advanced Pelvic Malignancies: A Phase I Study

    SciTech Connect (OSTI)

    Caravatta, Luciana [Department of Radiation Oncology, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy)] [Department of Radiation Oncology, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy); Padula, Gilbert D.A. [Department of Radiation Oncology, Lacks Cancer Center Saint Mary's Health Care, Grand Rapids, MI (United States)] [Department of Radiation Oncology, Lacks Cancer Center Saint Mary's Health Care, Grand Rapids, MI (United States); Macchia, Gabriella, E-mail: gmacchia@rm.unicatt.it [Department of Radiation Oncology, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy)] [Department of Radiation Oncology, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy); Ferrandina, Gabriella [Department of Gynecologic Oncology, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy)] [Department of Gynecologic Oncology, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy); Bonomo, Pierluigi; Deodato, Francesco; Massaccesi, Mariangela [Department of Radiation Oncology, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy)] [Department of Radiation Oncology, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy); Mignogna, Samantha; Tambaro, Rosa [Department of Palliative Therapies, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy)] [Department of Palliative Therapies, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy); Rossi, Marco [Department of Anaesthesia, Intensive Care, and Pain Medicine, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy)] [Department of Anaesthesia, Intensive Care, and Pain Medicine, Fondazione di Ricercae Cura 'Giovanni Paolo II,' Universita Cattolica del S. Cuore, Campobasso (Italy); Flocco, Mariano ['Madre Teresa di Calcutta' Hospice, Larino (Italy)] ['Madre Teresa di Calcutta' Hospice, Larino (Italy); Scapati, Andrea [Department of Radiation Oncology, 'San Francesco' Hospital, Nuoro (Italy)] [Department of Radiation Oncology, 'San Francesco' Hospital, Nuoro (Italy); and others

    2012-08-01T23:59:59.000Z

    Purpose: To define the maximum tolerated dose of a conformal short-course accelerated radiotherapy in patients with symptomatic advanced pelvic cancer. Methods and Materials: A phase I trial in 3 dose-escalation steps was designed: 14 Gy (3.5-Gy fractions), 16 Gy (4-Gy fractions), and 18 Gy (4.5-Gy fractions). The eligibility criteria included locally advanced and/or metastatic pelvic cancer and Eastern Cooperative Oncology Group performance status of {<=}3. Treatment was delivered in 2 days with twice-daily fractionation and at least an 8-hour interval. Patients were treated in cohorts of 6-12 to define the maximum tolerated dose. The dose-limiting toxicity was defined as any acute toxicity of grade 3 or greater, using the Radiation Therapy Oncology Group scale. Pain was recorded using a visual analog scale. The effect on quality of life was evaluated according to Cancer Linear Analog Scale (CLAS). Results: Of the 27 enrolled patients, 11 were male and 16 were female, with a median age of 72 years (range 47-86). The primary tumor sites were gynecologic (48%), colorectal (33.5%), and genitourinary (18.5%). The most frequent baseline symptoms were bleeding (48%) and pain (33%). Only grade 1-2 acute toxicities were recorded. No patients experienced dose-limiting toxicity. With a median follow-up time of 6 months (range 3-28), no late toxicities were observed. The overall (complete plus partial) symptom remission was 88.9% (95% confidence interval 66.0%-97.8%). Five patients (41.7%) had complete pain relief, and six (50%) showed >30% visual analog scale reduction. The overall response rate for pain was 91.67% (95% confidence interval 52.4%-99.9%). Conclusions: Conformal short course radiotherapy in twice-daily fractions for 2 consecutive days was well tolerated up to a total dose of 18 Gy. A phase II study is ongoing to confirm the efficacy on symptom control and quality of life indexes.

  8. Demonstration of a novel technique to measure two-photon exchange effects in elastic e±p scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Moteabbed, Maryam [Florida Institute of Technology; Niroula, Megh [Old Dominion University; Raue, Brian [Florida International University; Weinstein, Lawrence [Old Dominion University

    2013-08-01T23:59:59.000Z

    The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. The TPE contributions depend on the sign of the lepton charge in e±p scattering, but the luminosities of secondary positron beams limited past measurement at large scattering angles, where the TPE effects are believe to be most significant. We present the results of a new experimental technique for making direct e±p comparisons, which has the potential to make precise measurements over a broad range in Q2 and scattering angles. We use the Jefferson Laboratory electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of Q2 and scattering angle. Nonetheless, this measurement yields a data sample for e±p with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. Because we ran with only one polarity for the chicane, we are unable to study the difference between the incoming electron and positron beams. This systematic effect leads to the largest uncertainty in the final ratio of positron to electron scattering: R=1.027±0.005±0.05 for 2 >=0.206 GeV2 and 0.830 ? ? ? 0.943. We have demonstrated that the tertiary e± beam generated using this technique provides the opportunity for dramatically improved comparisons of e±p scattering, covering a significant range in both Q2 and scattering angle. Combining data with different chicane polarities will allow for detailed studies of the difference between the incoming e+ and e- beams.

  9. Demonstration of a novel technique to measure two-photon exchange effects in elastic e±p scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Moteabbed, Maryam; Niroula, Megh; Raue, Brian; Weinstein, Lawrence

    2013-08-01T23:59:59.000Z

    The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. The TPE contributions depend on the sign of the lepton charge in e±p scattering, but the luminosities of secondary positron beams limited past measurement at large scattering angles, where the TPE effects are believe to be most significant. We present the results of a new experimental technique for making direct e±p comparisons, which has themore »potential to make precise measurements over a broad range in Q2 and scattering angles. We use the Jefferson Laboratory electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of Q2 and scattering angle. Nonetheless, this measurement yields a data sample for e±p with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. Because we ran with only one polarity for the chicane, we are unable to study the difference between the incoming electron and positron beams. This systematic effect leads to the largest uncertainty in the final ratio of positron to electron scattering: R=1.027±0.005±0.05 for 2 >=0.206 GeV2 and 0.830 ? ? ? 0.943. We have demonstrated that the tertiary e± beam generated using this technique provides the opportunity for dramatically improved comparisons of e±p scattering, covering a significant range in both Q2 and scattering angle. Combining data with different chicane polarities will allow for detailed studies of the difference between the incoming e+ and e- beams.« less

  10. Demonstration of a novel technique to measure two-photon exchange effects in elastic e±p scattering

    SciTech Connect (OSTI)

    Moteabbed, Maryam [Florida Institute of Technology; Niroula, Megh [Old Dominion University; Raue, Brian [Florida International University; Weinstein, Lawrence [Old Dominion University

    2013-08-01T23:59:59.000Z

    The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. The TPE contributions depend on the sign of the lepton charge in e±p scattering, but the luminosities of secondary positron beams limited past measurement at large scattering angles, where the TPE effects are believe to be most significant. We present the results of a new experimental technique for making direct e±p comparisons, which has the potential to make precise measurements over a broad range in Q2 and scattering angles. We use the Jefferson Laboratory electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of Q2 and scattering angle. Nonetheless, this measurement yields a data sample for e±p with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. Because we ran with only one polarity for the chicane, we are unable to study the difference between the incoming electron and positron beams. This systematic effect leads to the largest uncertainty in the final ratio of positron to electron scattering: R=1.027±0.005±0.05 for < Q2 >=0.206 GeV2 and 0.830 ? ? ? 0.943. We have demonstrated that the tertiary e± beam generated using this technique provides the opportunity for dramatically improved comparisons of e±p scattering, covering a significant range in both Q2 and scattering angle. Combining data with different chicane polarities will allow for detailed studies of the difference between the incoming e+ and e- beams.