National Library of Energy BETA

Sample records for type-of-sale clas sification

  1. Introduction The CLAS Excited Baryon Program

    E-Print Network [OSTI]

    Credé, Volker

    Conference Montpellier, 07/08/2008 V. Credé Overview of CLAS Physics #12;Introduction The CLAS Excited Baryon Program The CLAS Polarization Program Summary and Outlook Outline 1 Introduction Physics with the CLAS. Credé Overview of CLAS Physics #12;Introduction The CLAS Excited Baryon Program The CLAS Polarization

  2. CLAS12 Software Readiness Review -Replay Jerry Gilfoyle (for the CLAS12 Software Group)

    E-Print Network [OSTI]

    Gilfoyle, Jerry

    CLAS12 Software Readiness Review - Replay Jerry Gilfoyle (for the CLAS12 Software Group) Physics Department, University of Richmond, Virginia Outline: 0. History 1. Introduction 2. Software Framework 3 spectrometer based on CLAS6. Luminosity increases by a factor of ten over CLAS6 (L = 1035 cm-2s-1). Software

  3. Spin Physics with CLAS

    SciTech Connect (OSTI)

    Yelena Prok

    2010-05-01

    Inelastic scattering using polarized nucleon targets and polarized charged lepton beams allows the extraction of double and single spin asymmetries that provide information about the helicity structure of the nucleon. A program designed to study such processes at low and intermediate $Q^2$ for the proton and deuteron has been pursued by the CLAS Collaboration at Jefferson Lab since 1998. Our inclusive data with high statistical precision and extensive kinematic coverage allow us to better constrain the polarized parton distributions and to accurately determine various moments of spin structure function $g_1$ as a function of $Q^2$. The latest results will be shown, illustrating our contribution to the world data, with comparisons of the data with NLO global fits, phenomenological models, chiral perturbation theory and the GDH and Bjorken sum rules. The semi-inclusive measurements of single and double spin asymmetries for charged and neutral pions are also show, indicating the importance of the orbital motion of quarks in understanding the spin structure of the nucleon.

  4. Deeply virtual Compton scattering with CLAS and CLAS12

    SciTech Connect (OSTI)

    Sokhan, Daria [Institut de Physique Nucleaire, Orsay, France

    2012-06-01

    Generalised Parton Distributions (GPDs) offer an insight into the three-dimensional structure of the nucleon and its internal dynamics, relating the transverse position of quarks to their longitudinal momentum. Two effective means of accessing GPDs are Deeply Virtual Compton Scattering (DVCS) and Meson Production (DVMP), in which a high energy electron scatters from a single quark in the nucleon and, respectively, a real photon or meson is produced as a result. Jefferson Laboratory (JLab), USA, is ideally suited for measuring these processes and a very active experimental programme has been underway in the recent years, making use of the lab's continuous electron beam up to 6 GeV in energy and its large angle spectrometer CLAS. In the future, a vast, new, as-yet unprobed kinematic region will become experimentally accessible when the current upgrade of the JLab accelerator to operate at a maximum energy of 12 GeV is completed in a few years. It is being complemented by the construction of a new suite of detectors, CLAS12, a number of them optimised specifically for exclusive reconstruction of DVCS and DVMP in the new kinematic region. We present a selection of recent results of DVCS and DVMP measurements using CLAS and introduce the exciting experimental programme planned for the future with CLAS12.

  5. Studies of TMDs with CLAS

    SciTech Connect (OSTI)

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

    2013-07-01

    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.

  6. CLAS12 Software Readiness Review Jerry Gilfoyle (for the CLAS12 Software Group)

    E-Print Network [OSTI]

    Gilfoyle, Jerry

    CLAS12 Software Readiness Review Jerry Gilfoyle (for the CLAS12 Software Group) Physics Department, University of Richmond, Virginia Outline: 1. Introduction 2. Software Framework 3. Management 4. Requirements by a factor of ten over CLAS6 (L = 1035 cm-2s-1). Software Goal: Ready to analyze data at turn on (October

  7. Cascade photo production at CLAS

    SciTech Connect (OSTI)

    Goetz, John; Hicks, Kenneth H.

    2014-09-01

    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.

  8. CLAS12 Software Workshop Broad view of the state-of-the-art in

    E-Print Network [OSTI]

    Gilfoyle, Jerry

    CLAS12 Software Workshop Goals: Broad view of the state-of-the-art in offline analysis. Status of the CLAS12 software program. Opportunities for users to join that program. Tutorials on CLAS12 software://conferences.jlab.org/CLAS12Software/index.html CLAS12 Software Workshop ­ p. 1/ #12;CLAS12 Software Workshop Program (Morning

  9. Biological Sciences http://www.clas.wayne.edu/biology/

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    Biological Sciences http://www.clas.wayne.edu/biology/ Divisions: Evolutionary and Organismal Biology Molecular Biology and Biotechnology Cellular, Developmental, and Neurobiology #12;Biological Sciences http://www.clas.wayne.edu/biology/ · Cell Biology and Cytogenetics (Beningo, Tucker, Greenberg

  10. Hyperon Photo and Electro Production at CLAS

    E-Print Network [OSTI]

    Reinhard Schumacher

    2009-11-04

    Developments in strangeness photo- and electro- production off the proton, as investigated using the CLAS system in Hall B at Jefferson Lab, are discussed in this paper. By measuring sufficient spin observables one can decompose the reaction mechanism into elementary amplitudes. We discuss progress toward this end in recent data from CLAS, including cross sections and spin observables. We next discuss new results on the mass distribution of the $\\Lambda(1405)$, which shows signs of being a composite meson-baryon object of mixed isospin. The work on other hyperons such as the $\\Xi$ resonances will be mentioned, and future prospects outlined.

  11. Deeply Virtual Pseudoscalar Meson Production with CLAS

    E-Print Network [OSTI]

    V. Kubarovsky; P. Stoler; I. Bedlinsky; for the CLAS Collaboration

    2008-02-12

    Deeply virtual meson scattering cross sections and asymmetries for the pi^0 and eta exclusive electroproduction in a very wide kinematic range of Q^2, t and x_B have been measured with CLAS (JLab). Initial analysis is already showing remarkable results. These data will help us to better understand the transition from soft to hard mechanisms.

  12. Search for New and Unusual Strangeonia using CLAS

    SciTech Connect (OSTI)

    Saini, Mukesh Satyapraka

    2013-03-01

    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.

  13. DVCS with a Longitudinally Polarized Target with CLAS12

    SciTech Connect (OSTI)

    Egiyan, Hovanes; Biselli, Angela

    2009-08-04

    We describe a planned experiment to measure the longitudinal target-spin asymmetry in the DVCS process using CLAS12 detector. While the beam-spin asymmetry is more sensitive to H GPD, measurements of the target-spin asymmetry allow us to access the H-tilde GPD. These data will extend the Q{sup 2} range accessable by the existing CLAS data and the scheduled 6 GeV CLAS DVCS experiments to Q{sup 2} = 8 GeV{sup 2}.

  14. Di-hadron SIDIS measurements at CLAS

    SciTech Connect (OSTI)

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

    2014-06-01

    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.

  15. Photodisintegration of Light Nuclei with CLAS

    SciTech Connect (OSTI)

    Ilieva, Yordanka Yordanova [University of South Carolina; Zachariou, Nicholas [University of South Carolina

    2013-08-01

    We report preliminary results of photodisintegration of deuteron and {sup 3}He measured with CLAS at Jefferson Lab. We have extracted the beam-spin asymmetry for the {vector {gamma}}d {yields} pn reaction at photon energies from 1.1 GeV to 2.3 GeV and proton center-of-mass (c.m.) angles between 35{degrees}#14; and 135{degrees}#14;. Our data show interesting evolution of the angular dependence of the observable as the photon energy increases. The energy dependence of the beam-spin asymmetry at 90#14; shows a change of slope at photon energy of 1.6 GeV. A comparison of our data with model calculations suggests that a fully non-perturbative treatment of the underlying dynamics may be able to describe the data better than a model based on hard scattering. We have observed onset of dimensional scaling in the cross section of two-body photodisintegration of {sup 3}He at remarkably low energy and momentum transfer, which suggests that partonic degrees of freedom may be relevant for the description of nuclei at energies lower than previously considered.

  16. CLAS12 Software Workshop University of Richmond, May 25-26, 2010

    E-Print Network [OSTI]

    Gilfoyle, Jerry

    WELCOME! CLAS12 Software Workshop University of Richmond, May 25-26, 2010 Physics with the Energy? Develop a new picture of the structure of the nucleon and other hadrons. CLAS12 Software Workshop - May 25, 2010 ­ p. 1/ #12;CEBAF - The Way It Is. CLAS12 Software Workshop - May 25, 2010 ­ p. 2/ #12;CEBAF

  17. Photoproduction and Decay of Light Mesons in CLAS

    SciTech Connect (OSTI)

    Amaryan, Moskov Jamalovich

    2013-08-01

    We present preliminary experimental results on photoproduction and decay of light mesons measured with CLAS setup at JLAB . This include Dalitz decay of pseudoscalar and vector mesons, radiative decay of pseudoscalar mesons as well hadronic decays of pseudoscalar and vector mesons. The collected high statistics in some of decay channels exceeds the world data by an order of magnitude and some other decay modes are observed for the first time. It is shown how the CLAS data will improve the world data on transition form factors of light mesons, Dalitz plot analyses, branching ratios of rare decay modes and other fundamental properties potentially accessible through the light meson decays.

  18. PRO: CLAS Comprehensive Vitae Run Date: 4/4/2014

    E-Print Network [OSTI]

    in groundwater; Origins of isotopes and major and trace elements in formation waters (deep basin/oil & gas field: Oxford University Press, 1998. Macpherson, G. L., and M. A. Townsend. "Chapter 5, Water chemistry Association of GeoChemistry, June 2013 #12;Gwendolyn L. Macpherson 2 PRO: CLAS Comprehensive Vitae Run Date: 4

  19. Recent N* results from photoproduction experiments at CLAS

    SciTech Connect (OSTI)

    D. Sokhan

    2011-10-01

    The recent breakthroughs in the technology of polarized targets have enabled a new generation of meson photo-production experiments to be carried out. A measurement of a full set of polarization observables off both polarized proton and neutron tar gets and in a large number of meson-production channels has come within sight. Such a measurement would very significantly reduce model-dependence in the analysis of the data and thus has the potential to resolve long-standing issues, such as the 'missing resonance' problem, and shed new light on the nucleon excitation spectrum. This has formed the motivation for the recent N* experimental programme of CLAS.

  20. A Bayesian analysis of pentaquark signals from CLAS data

    SciTech Connect (OSTI)

    David Ireland; Bryan McKinnon; Dan Protopopescu; Pawel Ambrozewicz; Marco Anghinolfi; G. Asryan; Harutyun Avakian; H. Bagdasaryan; Nathan Baillie; Jacques Ball; Nathan Baltzell; V. Batourine; Marco Battaglieri; Ivan Bedlinski; Ivan Bedlinskiy; Matthew Bellis; Nawal Benmouna; Barry Berman; Angela Biselli; Lukasz Blaszczyk; Sylvain Bouchigny; Sergey Boyarinov; Robert Bradford; Derek Branford; William Briscoe; William Brooks; Volker Burkert; Cornel Butuceanu; John Calarco; Sharon Careccia; Daniel Carman; Liam Casey; Shifeng Chen; Lu Cheng; Philip Cole; Patrick Collins; Philip Coltharp; Donald Crabb; Volker Crede; Natalya Dashyan; Rita De Masi; Raffaella De Vita; Enzo De Sanctis; Pavel Degtiarenko; Alexandre Deur; Richard Dickson; Chaden Djalali; Gail Dodge; Joseph Donnelly; David Doughty; Michael Dugger; Oleksandr Dzyubak; Hovanes Egiyan; Kim Egiyan; Lamiaa Elfassi; Latifa Elouadrhiri; Paul Eugenio; Gleb Fedotov; Gerald Feldman; Ahmed Fradi; Herbert Funsten; Michel Garcon; Gagik Gavalian; Nerses Gevorgyan; Gerard Gilfoyle; Kevin Giovanetti; Francois-Xavier Girod; John Goetz; Wesley Gohn; Atilla Gonenc; Ralf Gothe; Keith Griffioen; Michel Guidal; Nevzat Guler; Lei Guo; Vardan Gyurjyan; Kawtar Hafidi; Hayk Hakobyan; Charles Hanretty; Neil Hassall; F. Hersman; Ishaq Hleiqawi; Maurik Holtrop; Charles Hyde; Yordanka Ilieva; Boris Ishkhanov; Eugeny Isupov; D. Jenkins; Hyon-Suk Jo; John Johnstone; Kyungseon Joo; Henry Juengst; Narbe Kalantarians; James Kellie; Mahbubul Khandaker; Wooyoung Kim; Andreas Klein; Franz Klein; Mikhail Kossov; Zebulun Krahn; Laird Kramer; Valery Kubarovsky; Joachim Kuhn; Sergey Kuleshov; Viacheslav Kuznetsov; Jeff Lachniet; Jean Laget; Jorn Langheinrich; D. Lawrence; Kenneth Livingston; Haiyun Lu; Marion MacCormick; Nikolai Markov; Paul Mattione; Bernhard Mecking; Mac Mestayer; Curtis Meyer; Tsutomu Mibe; Konstantin Mikhaylov; Marco Mirazita; Rory Miskimen; Viktor Mokeev; Brahim Moreno; Kei Moriya; Steven Morrow; Maryam Moteabbed; Edwin Munevar Espitia; Gordon Mutchler; Pawel Nadel-Turonski; Rakhsha Nasseripour; Silvia Niccolai; Gabriel Niculescu; Maria-Ioana Niculescu; Bogdan Niczyporuk; Megh Niroula; Rustam Niyazov; Mina Nozar; Mikhail Osipenko; Alexander Ostrovidov; Kijun Park; Evgueni Pasyuk; Craig Paterson; Sergio Pereira; Joshua Pierce; Nikolay Pivnyuk; Oleg Pogorelko; Sergey Pozdnyakov; John Price; Sebastien Procureur; Yelena Prok; Brian Raue; Giovanni Ricco; Marco Ripani; Barry Ritchie; Federico Ronchetti; Guenther Rosner; Patrizia Rossi; Franck Sabatie; Julian Salamanca; Carlos Salgado; Joseph Santoro; Vladimir Sapunenko; Reinhard Schumacher; Vladimir Serov; Youri Sharabian; Dmitri Sharov; Nikolay Shvedunov; Elton Smith; Lee Smith; Daniel Sober; Daria Sokhan; Aleksey Stavinskiy; Samuel Stepanyan; Stepan Stepanyan; Burnham Stokes; Paul Stoler; Steffen Strauch; Mauro Taiuti; David Tedeschi; Ulrike Thoma; Avtandil Tkabladze; Svyatoslav Tkachenko; Clarisse Tur; Maurizio Ungaro; Michael Vineyard; Alexander Vlassov; Daniel Watts; Lawrence Weinstein; Dennis Weygand; M. Williams; Elliott Wolin; M.H. Wood; Amrit Yegneswaran; Lorenzo Zana; Jixie Zhang; Bo Zhao; Zhiwen Zhao

    2008-02-01

    We examine the results of two measurements by the CLAS collaboration, one of which claimed evidence for a $\\Theta^{+}$ pentaquark, whilst the other found no such evidence. The unique feature of these two experiments was that they were performed with the same experimental setup. Using a Bayesian analysis we find that the results of the two experiments are in fact compatible with each other, but that the first measurement did not contain sufficient information to determine unambiguously the existence of a $\\Theta^{+}$. Further, we suggest a means by which the existence of a new candidate particle can be tested in a rigorous manner.

  1. K^*0 Photoproduction off the proton at CLAS

    E-Print Network [OSTI]

    I. Hleiqawi; K. Hicks

    2006-01-01

    We report here differential cross sections for the reaction $\\gamma p \\to K^{*0}\\Sigma^+$ for the first time with high statistics. The measurements were done using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Data were taken at 3.115 GeV electron beam energy using tagged photons incident upon a liquid hydrogen target. In addition, our analysis provides information about nucleon resonances and their couplings to $K^*$ decay. Our data will be used to test predictions of theoretical models of K$^*$ production, and to provide constraints on the $K^*\\Sigma N$ coupling constant used in these models.

  2. 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

    2013-01-11

    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

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

    SciTech Connect (OSTI)

    Inna Aznauryan, Volker Burkert, Viktor Mokeev

    2012-04-01

    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.

  4. eA Pion Production at CLAS Aimed at Neutrinos

    SciTech Connect (OSTI)

    Steven Manly

    2011-11-01

    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.

  5. Deeply virtual Compton Scattering cross section measured with CLAS

    SciTech Connect (OSTI)

    Guegan, Baptistse

    2014-09-01

    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. 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

    2005-10-01

    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.

  7. Status of Polarized PDFs and Higher Twist after the CLAS and COMPASS Data

    SciTech Connect (OSTI)

    Leader, Elliot [Imperial College, Prince Consort Road, London SW7 2BW (United Kingdom); Sidorov, Aleksander V. [Bogoliubov Theoretical Laboratory, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Stamenov, Dimiter B. [Institute for Nuclear Research and Nuclear Energy Bulgarian Academy of Sciences, Blvd. Tsarigradsko Chaussee 72, Sofia 1784 (Bulgaria)

    2007-11-19

    The impact of the recent very precise CLAS and COMPASS g{sub 1}/F{sub 1} data on polarized parton densities and higher twist effects is discussed. It is demonstrated that the low Q{sup 2} CLAS data improve essentially our knowledge of higher twist corrections to the spin structure function g{sub 1}, while the large Q{sup 2} COMPASS dala influence mainly the strange quark and gluon polarizations which slightly decrease. It is shown that the uncertainties in the determination of the polarized parlon densities are significantly reduced. We find also that the present inclusive DIS data cannot rule out a negative polarized and changing in sign gluon densities.

  8. Impact of CLAS and COMPASS data on polarized parton densities and higher twist

    SciTech Connect (OSTI)

    Leader, Elliot; Sidorov, Aleksander V.; Stamenov, Dimiter B. [Imperial College, Prince Consort Road, London SW7 2BW (United Kingdom); Bogoliubov Theoretical Laboratory Joint Institute for Nuclear Research, 141980 Dubna, (Russian Federation); Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Boulevard, Tsarigradsko Chaussee 72, Sofia 1784 (Bulgaria)

    2007-04-01

    We have reanalyzed the world data on inclusive polarized deep inelastic scattering (DIS) including the very precise CLAS proton and deuteron data, as well as the latest COMPASS data on the asymmetry A{sub 1}{sup d}, and have studied the impact of these data on polarized parton densities and higher twist effects. We demonstrate that the low Q{sup 2} CLAS data improve essentially our knowledge of higher twist corrections to the spin structure function g{sub 1}, while the large Q{sup 2} COMPASS data influence mainly the strange quark density. In our new analysis we find that a negative polarized gluon density, or one that changes sign as a function of x, cannot be ruled out on the basis of the present DIS data.

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

    SciTech Connect (OSTI)

    K.A. Griffioen

    2012-12-01

    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.

  10. Hadronic Multi-Particle Final State Measurements with CLAS at Jefferson Lab

    E-Print Network [OSTI]

    W. K. Brooks

    2003-11-04

    Precision measurements in the neutrino sector are becoming increasingly feasible due to the development of relatively high-rate experimental capabilities. These important developments command renewed attention to the systematic corrections needed to interpret the data. Hadronic multi-particle final state measurements made using CLAS at Jefferson Lab, together with a broad theoretical effort that links electro-nucleus and neutrino-nucleus data, will address this problem, and will elucidate long-standing problems in intermediate energy nuclear physics. This new work will ultimately enable precision determinations of fundamental quantities such as the neutrino mixing matrix elements in detailed studies of neutrino oscillations.

  11. Theoretical study of the $?$(1520) photoproduction off proton target based on the new CLAS data

    E-Print Network [OSTI]

    Jun He

    2014-05-06

    Based on the high precision experimental data released by the CLAS Collaboration recently, the interaction mechanism of the photoproduction of $\\Lambda$(1520) off a proton target is investigated within a Regge-plus-resonance approach. With the decay amplitudes predicted in the constituent quark model, the roles played by nucleon resonances are studied. It is found that $N(2120)$ provides the most important contribution among the nucleon resonances predicted in the constituent quark model. The $t$ channel contribution with Regge trajectories and the $\\Lambda$ intermediate $u$ channel are responsible to the behaviors of the differential cross section at forward and backward angles, respectively.

  12. Measurement of the nuclear multiplicity ratio or image hadronization K0s at CLAS

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

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

    2011-11-01

    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 K0s 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 K0sand the transverse momentum squared p2T of the K0s. We find that the multiplicity ratios for K0s are reduced in the nuclear medium at high z and low p2T, with a trend for the K0s transverse momentum tomore »be broadened in the nucleus for large p2T.« less

  13. Search for the Theta+ pentaquark in the gamma d -> Lambda n K+ reaction measured with CLAS

    SciTech Connect (OSTI)

    Silvia Niccolai; Marco Mirazita; Patrizia Rossi; Nathan Baltzell; Daniel Carman; Kenneth Hicks; Bryan McKinnon; Tsutomu Mibe; Stepan Stepanyan; David Tedeschi; Gary Adams; Pawel Ambrozewicz; Sergio Pereira; Marco Anghinolfi; Gegham Asryan; Harutyun AVAKIAN; H. Bagdasaryan; Nathan Baillie; Jacques Ball; V. Batourine; Marco Battaglieri; Ivan Bedlinski; Ivan Bedlinskiy; Ivan Bedlinski; Ivan Bedlinskiy; Mehmet Bektasoglu; Matthew Bellis; Nawal Benmouna; Barry Berman; Angela Biselli; Sergey Boyarinov; Sylvain Bouchigny; Robert Bradford; Derek Branford; William Briscoe; William Brooks; Stephen Bueltmann; Volker Burkert; Cornel Butuceanu; John Calarco; S.L. Careccia; Bryan Carnahan; Shifeng Chen; Philip Cole; Patrick Collins; Philip Coltharp; Donald Crabb; Hall Crannell; V. Crede; John Cummings; Natalya Dashyan; Pavel Degtiarenko; Rita De Masi; Airton Deppman; Enzo De Sanctis; Alexandre Deur; Raffaella De Vita; Kahanawita Dharmawardane; Chaden Djalali; Gail Dodge; Joseph Donnelly; David Doughty; Michael Dugger; Oleksandr Dzyubak; Hovanes Egiyan; Kim Egiyan; L. El Fassi; Latifa Elouadrhiri; Paul Eugenio; Gleb Fedotov; Gerald Feldman; Herbert Funsten; Michel Garcon; Gagik Gavalian; Gerard Gilfoyle; Kevin Giovanetti; Francois-Xavier Girod; John Goetz; Atilla Gonenc; Christopher Gordon; Ralf Gothe; Keith Griffioen; Michel Guidal; Nevzat Guler; Lei Guo; Vardan Gyurjyan; Cynthia Hadjidakis; Kawtar Hafidi; Hayk Hakobyan; Rafael Hakobyan; John Hardie; F. Hersman; Ishaq Hleiqawi; Maurik Holtrop; Charles Hyde-Wright; Yordanka Ilieva; David Ireland; Boris Ishkhanov; Eugeny Isupov; Mark Ito; David Jenkins; Hyon-Suk Jo; Kyungseon Joo; Henry Juengst; James Kellie; Mahbubul Khandaker; Wooyoung Kim; Andreas Klein; Franz Klein; Alexei Klimenko; Mikhail Kossov; Laird Kramer; V. Kubarovsky; Joachim Kuhn; Sebastian Kuhn; Sergey Kuleshov; Jeff Lachniet; Jorn Langheinrich; David Lawrence; Tsung-shung Lee; Kenneth Livingston; H. Lu; Marion MacCormick; Nikolai Markov; Bernhard Mecking; Jonathan Mellor; Joseph Melone; Mac Mestayer; Curtis Meyer; Konstantin Mikhaylov; Ralph Minehart; Rory Miskimen; Viktor Mokeev; Ludyvine Morand; Steven Morrow; Maryam Moteabbed; Gordon Mutchler; Pawel Nadel-Turonski; James Napolitano; Rakhsha Nasseripour; Gabriel Niculescu; Maria-Ioana Niculescu; Bogdan Niczyporuk; Megh Niroula; Rustam Niyazov; Mina Nozar; Jorge De Olivei Echeimberg; Mikhail Osipenko; Alexander Ostrovidov; K. Park; Evgueni Pasyuk; Craig Paterson; Joshua Pierce; Nikolay Pivnyuk; Dinko Pocanic; Oleg Pogorelko; Sergey Pozdnyakov; Barry Preedom; John Price; Yelena Prok; Dan Protopopescu; Brian Raue; Gregory Riccardi; Giovanni Ricco; Marco Ripani; Barry Ritchie; Federico Ronchetti; Guenther Rosner; Franck Sabatie; Carlos Salgado; Joseph Santoro; Vladimir Sapunenko; Reinhard Schumacher; Vladimir Serov; Youri Sharabian; Nikolay Shvedunov; Elton Smith; Lee Smith; Daniel Sober; Aleksey Stavinskiy; Stepan Stepanyan; Burnham Stokes; Paul Stoler; Igor Strakovski; Steffen Strauch; Mauro Taiuti; Ulrike Thoma; Avtandil Tkabladze; Svyatoslav Tkachenko; Luminita Todor; Clarisse Tur; Maurizio Ungaro; Michael Vineyard; Alexander Vlassov; Daniel Watts; Lawrence Weinstein; Dennis Weygand; M. Williams; Elliott Wolin; Michael Wood; Amrit Yegneswaran; Lorenzo Zana; Jixie Zhang; Bo Zhao; Zhiwen Zhao

    2006-04-26

    For the first time, the reaction gamma d -> Lambda n K+ has been analyzed in order to search for the exotic pentaquark baryon Theta+(1540). The data were taken at Jefferson Lab, using the Hall-B tagged-photon beam of energy between 0.8 and 3.6 GeV and the CEBAF Large Acceptance Spectrometer (CLAS). No statistically significant structures were observed in the nK+ invariant mass distribution. The upper limit on the gamma d -> Lambda Theta+ integrated cross section has been calculated and found to be between 5 and 25 nb, depending on the production model assumed. The upper limit on the differential cross section is also reported.

  14. 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.

    2014-08-01

    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.

  15. Test of the CLAS12 RICH large scale prototype in the direct proximity focusing configuration

    E-Print Network [OSTI]

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

    2015-09-09

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c up to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Laboratory. The adopted solution foresees a novel hybrid optics design based on aerogel radiator, composite mirrors and high-packed and high-segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). We report here the results of the tests of a large scale prototype of the RICH detector performed with the hadron beam of the CERN T9 experimental hall for the direct detection configuration. The tests demonstrated that the proposed design provides the required pion-to-kaon rejection factor of 1:500 in the whole momentum range.

  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

    2011-11-30

    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. Test of the CLAS12 RICH large scale prototype in the direct proximity focusing configuration

    E-Print Network [OSTI]

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

    2015-01-01

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c up to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Laboratory. The adopted solution foresees a novel hybrid optics design based on aerogel radiator, composite mirrors and high-packed and high-segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). We report here the results of the tests of a large scale prototype of the RICH detector performed with the hadron beam of the CERN T9 experimental hall for the direct detection configuration. The tests demonstrated that the proposed design provides the required pion-to-kaon rejection factor of 1:500 in the whole momentum range.

  18. 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

    2013-02-02

    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.

  19. 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

    2014-05-05

    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.

  20. Analysis of recent CLAS data on $\\Sigma ^{\\ast }(1385)$ photoproduction off a neutron target

    E-Print Network [OSTI]

    Wang, Xiao-Yun; Haberzettl, Helmut

    2015-01-01

    Based on recent experimental data obtained by the CLAS Collaboration, the $\\Sigma(1385)$ photoproduction off a neutron target at laboratory photon energies $E_\\gamma$ up to 2.5\\,GeV is investigated in an effective Lagrangian approach including $s$-, $u$-, and $t$-channel Born-term contributions. The present calculation does not take into account any explicit $s$-channel baryon-resonance contributions, however, in the spirit of duality, we include $t$-channel exchanges of mesonic Regge trajectories. The onset of the Regge regime is controlled by smoothly interpolating between Feynman-type single-meson exchanges and full-fledged Regge-trajectory exchanges. Gauge invariance broken by the Regge treatment is fully restored by introducing contact-type interaction currents that result from the implementation of \\textit{local} gauge invariance in terms of generalized Ward-Takahashi identities. The cross sections for the $\\gamma n\\to K^+\\Sigma^*(1385)^-$ reaction are calculated and compared with experimental results f...

  1. Development of Bayesian analysis program for extraction of polarisation observables at CLAS

    SciTech Connect (OSTI)

    Lewis, Stefanie; Ireland, David; Vanderbauwhede, W.

    2014-06-01

    At the mass scale of a proton, the strong force is not well understood. Various quark models exist, but it is important to determine which quark model(s) are most accurate. Experimentally, finding resonances predicted by some models and not others would give valuable insight into this fundamental interaction. Several labs around the world use photoproduction experiments to find these missing resonances. The aim of this work is to develop a robust Bayesian data analysis program for extracting polarisation observables from pseudoscalar meson photoproduction experiments using CLAS at Jefferson Lab. This method, known as nested sampling, has been compared to traditional methods and has incorporated data parallelisation and GPU programming. It involves an event-by-event likelihood function, which has no associated loss of information from histogram binning, and results can be easily constrained to the physical region. One of the most important advantages of the nested sampling approach is that data from different experiments can be combined and analysed simultaneously. Results on both simulated and previously analysed experimental data for the K{sup +}? channel will be discussed.

  2. ..sification No.: 1000.27 ,proval.Oate: 3/14/92

    E-Print Network [OSTI]

    , Inspectors General, and General Counsels. Finally, the historical archives will include some materials copied, working papers, and internal reports. All protected materials--such as payroll and personnel documents of various EPA offices, ad hoc reports or historical studies on special topics. #12;EPA· Order 3

  3. 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

    2012-09-13

    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

  4. Precise determination of the deuteron spin structure at low to moderate Q2 with CLAS and extraction of the neutron contribution

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

    Guler, N.; Fersch, R. G.; Kuhn, S. E.; Bosted, P.; Griffioen, K. A.; Keith, C.; Minehart, R.; Prok, Y.; Adhikari, K. P.; Adikaram, D.; et al

    2015-11-02

    In this study, 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 (15ND3) targets, dynamically polarized along the beam direction, and detected with CLAS. From the measured double spin asymmetry, the virtual photon absorption asymmetry Ad1 and the polarized structure function gd1 were extracted over a wide kinematic range (0.05 GeV2 more »a parametrization of the corresponding proton results to extract from these data the polarized structure functions An1 and g1n of the (bound) neutron, which are so far unknown in the resonance region, W « less

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

    SciTech Connect (OSTI)

    Mattione, Paul

    2014-09-01

    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.

  6. Target and Double Spin Asymmetries of Deeply Virtual $\\pi^0$ Production with a Longitudinally Polarized Proton Target and CLAS

    E-Print Network [OSTI]

    Kim, A; Burkert, V; Joo, K; Kim, W; Adhikari, K P; Akbar, Z; Pereira, S Anefalos; Badui, R A; Battaglieri, M; Batourine, V; Bedlinskiy, I; Biselli, A S; Boiarinov, S; Briscoe, W J; Brooks, W K; Bültmann, S; Cao, T; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Chetry, T; Colaneri, L; Cole, P L; Compton, N; Contalbrigo, M; Cortes, O; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Djalali, C; Egiyan, H; Alaoui, A El; Fassi, L El; Eugenio, P; Fedotov, G; Fersch, R; Filippi, A; Fleming, J A; Fradi, A; Garçon, M; Ghandilyan, Y; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Gohn, W; Golovatch, E; Gothe, R W; Griffioen, K A; Guo, L; Hafidi, K; Hanretty, C; Hattawy, M; Heddle, D; Hicks, K; Holtrop, M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Jenkins, D; Jiang, H; Jo, H S; Joosten, S; Keller, D; Khachatryan, G; Khandaker, M; Klein, A; Klein, F J; Kubarovsky, V; Kuhn, S E; Kuleshov, S V; Lanza, L; Lenisa, P; Lu, H Y; MacGregor, I J D; Markov, N; Mattione, P; McCracken, M E; McKinnon, B; Mokeev, V; Movsisyan, A; Munevar, E; Nadel-Turonski, P; Net, L A; Niccolai, S; Osipenko, M; Ostrovidov, A I; Paolone, M; Park, K; Pasyuk, E; Phelps, W; Pisano, S; Pogorelko, O; Price, J W; Prok, Y; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Salgado, C; Schumacher, R A; Seder, E; Sharabian, Y G; Skorodumina, Iu; Smith, G D; Sokhan, D; Sparveris, N; Stepanyan, S; Stoler, P; Strakovsky, I I; Strauch, S; Sytnik, V; Taiuti, M; Torayev, B; Ungaro, M; Voskanyan, H; Voutier, E; Watts, D P; Wei, X; Weinstein, L B; Zachariou, N; Zana, L; Zhang, J; Zonta, I

    2015-01-01

    The target and double spin asymmetries of the exclusive pseudoscalar channel $\\vec e\\vec p\\to ep\\pi^0$ were measured for the first time in the deep-inelastic regime using a longitudinally polarized 5.9 GeV electron beam and a longitudinally polarized proton target at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS). The data were collected over a large kinematic phase space and divided into 110 four-dimensional bins of $Q^2$, $x_B$, $-t$ and $\\phi$. Large values of asymmetry moments clearly indicate a substantial contribution to the polarized structure functions from transverse virtual photon amplitudes. The interpretation of experimental data in terms of generalized parton distributions (GPDs) provides the first insight on the chiral-odd GPDs $\\tilde{H}_T$ and $E_T$, and complement previous measurements of unpolarized structure functions sensitive to the GPDs $H_T$ and $\\bar E_T$. These data provide necessary constraints for chiral-odd GPD parametrizations and will strongly influence existin...

  7. Electromagnetic and Mechanical Analysis of the Coil Structure for the CLAS12 Torus for 12 GeV Upgrade

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

    Ghoshal, P. K.; Pastor, O.; Kashy, D.; Schneider, W.; Wiseman, M.; Zarecky, M.; Young, G.; Rode, C.; Elouadrhiri, L.; Burkert, V.

    2014-12-18

    The torus magnet for the CLAS12 spectrometer is a 3.6 T superconducting magnet being designed and built as part of the Jefferson Lab 12 GeV Upgrade. The magnet consists of six coil case assemblies mounted to a cold central hub. The coil case assembly consists of an aluminum case and cover enclosing an epoxy vacuum impregnated coil pack. The coil pack consists of a 117 turn double-pancake winding wrapped with 2 layers of 0.635 mm thick copper cooling sheets. The coil case assembly is cooled by supercritical helium at 4.6 K. This report details the structural analysis of the coilmore »case assembly and the assessment of the coil pack stresses. For the normal operation of the torus magnet, the coil case assembly was analyzed for cool down to 4.6 K and the Lorentz forces at normal operating current. In addition to the normal operating configuration, the coil case assembly was analyzed for Lorentz forces arising from coil misalignment and current imbalances. The allowable stress criteria for the magnet followed the approach of the ASME codes. Primary stresses were limited to the lesser of 2/3 times the yield strength or 1/3 times the ultimate tensile strength. Primary plus secondary stresses were limited to 3 times the primary stress allowable. The analysis was performed using ANSYS Maxwell to calculate the magneto-static loads and ANSYS Mechanical to calculate the stresses.« less

  8. Electromagnetic and Mechanical Analysis of the Coil Structure for the CLAS12 Torus for 12 GeV Upgrade

    SciTech Connect (OSTI)

    Ghoshal, P. K.; Pastor, O.; Kashy, D.; Schneider, W.; Wiseman, M.; Zarecky, M.; Young, G.; Rode, C.; Elouadrhiri, L.; Burkert, V.

    2014-12-18

    The torus magnet for the CLAS12 spectrometer is a 3.6 T superconducting magnet being designed and built as part of the Jefferson Lab 12 GeV Upgrade. The magnet consists of six coil case assemblies mounted to a cold central hub. The coil case assembly consists of an aluminum case and cover enclosing an epoxy vacuum impregnated coil pack. The coil pack consists of a 117 turn double-pancake winding wrapped with 2 layers of 0.635 mm thick copper cooling sheets. The coil case assembly is cooled by supercritical helium at 4.6 K. This report details the structural analysis of the coil case assembly and the assessment of the coil pack stresses. For the normal operation of the torus magnet, the coil case assembly was analyzed for cool down to 4.6 K and the Lorentz forces at normal operating current. In addition to the normal operating configuration, the coil case assembly was analyzed for Lorentz forces arising from coil misalignment and current imbalances. The allowable stress criteria for the magnet followed the approach of the ASME codes. Primary stresses were limited to the lesser of 2/3 times the yield strength or 1/3 times the ultimate tensile strength. Primary plus secondary stresses were limited to 3 times the primary stress allowable. The analysis was performed using ANSYS Maxwell to calculate the magneto-static loads and ANSYS Mechanical to calculate the stresses.

  9. 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.

    2014-01-01

    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.

  10. 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

    2015-06-01

    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.

  11. 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

  12. SONG-LEVEL FEATURES AND SUPPORT VECTOR MACHINES FOR MUSIC CLASSIFICATION

    E-Print Network [OSTI]

    Ellis, Dan

    ,dpwe}@ee.columbia.edu ABSTRACT Searching and organizing growing digital music collec- tions requires automatic classificationSONG-LEVEL FEATURES AND SUPPORT VECTOR MACHINES FOR MUSIC CLASSIFICATION Michael I. Mandel improves clas- sification. Further gains are also seen when using Sup- Permission to make digital or hard

  13. Characterization of Temporal Property Classes \\Lambda Edward Chang y & Zohar Manna y & Amir Pnueli z

    E-Print Network [OSTI]

    Manna, Zohar

    Characterization of Temporal Property Classes \\Lambda Edward Chang y & Zohar Manna y & Amir Pnueli z September 8, 1995 Abstract. This paper presents two novel characterizations of the classes of characterizations concerns the safety­progress clas­ sification, which describes a hierarchy within the set

  14. A&A manuscript no. (will be inserted by hand later)

    E-Print Network [OSTI]

    Jeffery, Simon

    /He ratio puts it between the clas­ sifications of an extreme and an intermediate helium star, and its low C of extreme ( nH = n He = 10 \\Gamma3 ) and intermediate ( nH = n He = 1) hydrogen deficient (H­def) stars to the group which includes HD124448 (Drilling 1986), or the unrecognised prototype of a recently defined group

  15. 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

  16. Querying Faceted Databases Columbia University Technical Report CUCS01303

    E-Print Network [OSTI]

    to subjects in sequence, but uses clearly defined, mutually exclusive, and col­ lectively exhaustive aspects are called facets of a class or subject, a term introduced into clas­ sification theory and given this new of entities. Our language has linear data complexity in terms of space and quadratic data complexity in terms

  17. uRule: A Rule-based Classification System for Uncertain Data

    E-Print Network [OSTI]

    Tu, Yicheng

    uRule: A Rule-based Classification System for Uncertain Data Biao Qin, Yuni Xia, Rakesh Sathyesh. In this demo,we will show uRule, a new rule-based clas- sification and prediction system for uncertain data measures are computed considering uncertain data intervals and probability distribution functions. Based

  18. 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

  19. Measurement of single spin asymmetry and fifth structure function for the proton(electron vec, electron Kaon+)Lambda reaction with CEBAF Large Acceptance Spectrometer (CLAS)

    SciTech Connect (OSTI)

    Rahksha Nasseripour

    2005-08-31

    The single spin asymmetry, A{sub LT} ?, and the polarized structure function, ?{sub LT}?, for the p(e,e?K{sup +})? reaction in the resonance region have been measured and extracted using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Data were taken at an electron beam energy of 2.567 GeV. The large acceptance of CLAS allows for full azimuthal angle coverage over a large range of center-of-mass scattering angles. Results were obtained that span a range in Q{sup 2} from 0.5 to 1.3 GeV{sup 2} and W from threshold up to 2.1 GeV and were compared to existing theoretical calculations. The polarized structure function is sensitive to the interferences between various resonant amplitudes, as well as to resonant and non-resonant amplitudes. This measurement is essential for understanding the structure of nucleons and searching for previously undetected nucleon excited states (resonances) predicted by quark models. The W dependence of the ?{sub LT} ? in the kinematic regions dominated by s and u channel exchange (cos q{sup cm} k = ?0.50, ?0.167, 0.167) indicated possible resonance structures not predicted by theoretical calculations. The ?{sub LT} ? behavior around W = 1.875 GeV could be the signature of a resonance predicted by the quark models and possibly seen in photoproduction. In the very forward angles where the reaction is dominated by the t-channel, the average ?{sub LT} ? was zero. There was no indication of the interference between resonances or resonant and non-resonant amplitudes. This might be indicating the dominance of a single t-channel exchange. Study of the sensitivity of the fifth structure function data to the resonance around 1900 MeV showed that these data were highly sensitive to the various assumptions of the models for the quantum number of this resonance. This project was part of a larger CLAS program to measure cross sections and polarization observables for kaon electroproduction in the nucleon resonance region.

  20. Search for baryon-number and lepton-number violating decays of $Lambda$ hyperons using the CLAS detector at Jefferson Laboratory

    SciTech Connect (OSTI)

    McCracken, Michael E.

    2015-10-09

    We present a search for ten baryon-number violating decay modes of $\\Lambda$ hyperons using the CLAS detector at Jefferson Laboratory. Nine of these decay modes result in a single meson and single lepton in the final state ($\\Lambda \\rightarrow m \\ell$) and conserve either the sum or the difference of baryon and lepton number ($B \\pm L$). The tenth decay mode ($\\Lambda \\rightarrow \\bar{p}\\pi^+$) represents a difference in baryon number of two units and no difference in lepton number. We observe no significant signal and set upper limits on the branching fractions of these reactions in the range $(4-200)\\times 10^{-7}$ at the $90\\%$ confidence level.

  1. Search for baryon-number and lepton-number violating decays of $Lambda$ hyperons using the CLAS detector at Jefferson Laboratory

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

    McCracken, Michael E.

    2015-10-09

    We present a search for ten baryon-number violating decay modes of $\\Lambda$ hyperons using the CLAS detector at Jefferson Laboratory. Nine of these decay modes result in a single meson and single lepton in the final state ($\\Lambda \\rightarrow m \\ell$) and conserve either the sum or the difference of baryon and lepton number ($B \\pm L$). The tenth decay mode ($\\Lambda \\rightarrow \\bar{p}\\pi^+$) represents a difference in baryon number of two units and no difference in lepton number. We observe no significant signal and set upper limits on the branching fractions of these reactions in the range $(4-200)\\times 10^{-7}$more »at the $90\\%$ confidence level.« less

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

    SciTech Connect (OSTI)

    Park, Kijun

    2014-09-01

    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.

  3. 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

    2014-10-03

    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.

  4. International Journal of Computer Vision manuscript No. (will be inserted by the editor)

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    to the popular Bag-of-Visual words (BoV) rep- resentation. In this work, we propose to use the Fisher Ker- nel, the most popular image representation for clas- sification has been the Bag-of-Visual words (BoV) (Csurka et al, 2004). In a nutshell, the BoV consists in extracting a set of local descriptors, such as SIFT

  5. CLAS: Civil Lawsuit Analysis System

    E-Print Network [OSTI]

    Shapiro, Max

    2015-01-01

    Conference on Artificial Intelligence and Law (pp. 249-255).conference on Artificial intelligence and law (pp. 190-191).Conference on Artificial Intelligence and Law (pp. 126-130).

  6. New Results from the Studies of the $N(1440)1/2^+$, $N(1520)3/2^-$, and $?(1620)1/2^-$ Resonances in Exclusive $ep \\to e'p' ?^+ ?^-$ Electroproduction with the CLAS Detector

    E-Print Network [OSTI]

    V. I. Mokeev; V. D. Burkert; D. S. Carman; L. Elouadrhiri; G. V. Fedotov; E. N. Golovatch; R. W. Gothe; K. Hicks; B. S. Ishkhanov; E. L. Isupov; Iu. Skorodumina

    2015-09-17

    The transition helicity amplitudes from the proton ground state to the $N(1440)1/2^+$, $N(1520)3/2^-$, and $\\Delta(1620)1/2^-$ resonances ($\\gamma_vpN^*$ electrocouplings) were determined from the analysis of nine independent one-fold differential $\\pi^+ \\pi^- p$ electroproduction cross sections off a proton target, taken with CLAS at photon virtualities 0.5 GeV$^2$ $offer clear evidence for the reliable extraction of these fundamental quantities. These studies also improved the knowledge on hadronic branching ratios for the $N(1440)1/2^+$, $N(1520)3/2^-$, and $\\Delta(1620)1/2^-$ decays to the $\\pi \\Delta$ and $\\rho N$ final states. These new results provide a substantial impact on the QCD-based approaches that describe the $N^*$ structure and demonstrate the capability to explore fundamental ingredients of the non-perturbative strong interaction that are behind the excited nucleon state formation.

  7. Electroproduction of p ?^{+} ?^{-} off protons at 0.2CLAS

    E-Print Network [OSTI]

    G. V. Fedotov; V. I. Mokeev; V. D. Burkert; L. Elouadrhiri; E. N. Golovatch; B. S. Ishkhanov; E. L. Isupov; N. V. Shvedunov; for the CLAS Collaboration

    2008-09-09

    This paper reports on the most comprehensive data set obtained on differential and fully integrated cross sections for the process $e p \\to e' p \\pi^{+} \\pi^{-} $. The data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the so-far unexplored kinematic region of photon virtuality 0.2 $analysis of the data allowed us to establish the most significant mechanisms contributing to the reaction. The non-resonant mechanisms account for a major part of cross-sections. However, we find sensitivity to s-channel excitations of low-mass nucleon resonances, especially to the $N(1440)P_{11}$ and $N(1520)D_{13}$ states in kinematical dependencies of the 1-fold differential cross-sections.

  8. 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

    2005-05-11

    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.

  9. February 14, 2013 1 College: CLAS

    E-Print Network [OSTI]

    Elzanowski, Marek

    , they can enter programs in optics, applied physics, engineering physics, and education. Biophysics popular fields, now. Environmental programs, electrical engineering, nuclear engineering, and computer, economy, environment, and the medical sciences. LO #05: Ability to access and critically analyze

  10. 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.

  11. February 14, 2013 1 College: CLAS

    E-Print Network [OSTI]

    Elzanowski, Marek

    conflict, gender, symbolic systems, and human ecology. Anthropologists apply the knowledge gained from in general survey courses (Anth 101, 102, 103) and in its departmental major program, a balanced view is offered for persons with particular regional or area interests, such as East Asia, South Asia, Latin

  12. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorking With WIPP UPDATE:Administrationfollowing tableUNITEDAutomated>

  13. 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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX E LISTStar2-0057-EA Jump to:of theClimateElgin, Illinois:JVEmpire

  14. 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

    2012-11-01

    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.

  15. mARC: Memory by Association and Reinforcement of Contexts

    E-Print Network [OSTI]

    Norbert Rimoux; Patrice Descourt

    2013-12-10

    This paper introduces the memory by Association and Reinforcement of Contexts (mARC). mARC is a novel data modeling technology rooted in the second quantization formulation of quantum mechanics. It is an all-purpose incremental and unsupervised data storage and retrieval system which can be applied to all types of signal or data, structured or unstructured, textual or not. mARC can be applied to a wide range of information clas-sification and retrieval problems like e-Discovery or contextual navigation. It can also for-mulated in the artificial life framework a.k.a Conway "Game Of Life" Theory. In contrast to Conway approach, the objects evolve in a massively multidimensional space. In order to start evaluating the potential of mARC we have built a mARC-based Internet search en-gine demonstrator with contextual functionality. We compare the behavior of the mARC demonstrator with Google search both in terms of performance and relevance. In the study we find that the mARC search engine demonstrator outperforms Google search by an order of magnitude in response time while providing more relevant results for some classes of queries.

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

    SciTech Connect (OSTI)

    Fink, Glenn A.; Oehmen, Christopher S.

    2012-09-01

    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.

  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.; Tkachenko, S.; Zhang, J.; Bosted, P.; Bültmann, S.; Christy, M. E.; Fenker, H.; Griffioen, K. A.; Keppel, C. E.; Kuhn, S. E.; et al

    2012-04-01

    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. 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

    2012-05-14

    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.

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

    SciTech Connect (OSTI)

    Baillie, N.; Tkachenko, S.; Zhang, J.; Bosted, P.; Bültmann, 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.; Anghinolfi, M.; Arrington, J.; Avakian, H.; Baghdasaryan, H.; Battaglieri, M.; Biselli, A. 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.; 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.; Sabatié, 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.; Zhao, B.

    2012-04-01

    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.

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

    SciTech Connect (OSTI)

    M. Battaglieri

    2004-07-20

    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.

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

    E-Print Network [OSTI]

    Silvia Niccolai; for the CLAS Collaboration

    2012-07-13

    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.

  2. Jefferson Lab CLAS12 Superconducting Solenoid magnet Requirements and Design Evolution

    SciTech Connect (OSTI)

    Rajput-Ghoshal, Renuka [Jefferson Lab, Newport News, VA; Hogan, John P. [Jefferson Lab, Newport News, VA; Fair, Ruben J. [Jefferson Lab, Newport News, VA; Ghoshal, Probir K. [Jefferson Lab, Newport News, VA; Luongo, Cesar [Jefferson Lab, Newport News, VA; Elouadrhiri, Latifa [Jefferson Lab, Newport News, VA

    2014-12-01

    As part of the Jefferson Lab 12GeV accelerator upgrade project, one of the experimental halls (Hall B) requires two superconducting magnets. One is a magnet system consisting of six superconducting trapezoidal racetrack-type coils assembled in a toroidal configuration and the second is an actively shielded solenoidal magnet system consisting of 5 coils. In this presentation the physics requirements for the 5 T solenoid magnet, design constraints, conductor decision, and cooling choice will be discussed. The various design iterations to meet the specification will also be discussed in this presentation.

  3. Nuclear Exclusive and Semi-inclusive Physics with a New CLAS12 Low

    E-Print Network [OSTI]

    Gilfoyle, Jerry

    of the processes needed to research these subjects require the detection of a low momentum recoil particle 5 2 Physics Topics 5 2.1 Coherent and incoherent DVCS on helium 5 2.2 Coherent DVCS on deuterium target 10 2.3 Neutron DVCS using deuterium and helium targets 11 2.4 Exclusive 0 electroproduction

  4. Determination of E and G Observables in n Photoproduction on the CLAS Frozen Spin Target (FROST)

    SciTech Connect (OSTI)

    Senderovich, Igor [University of Connecticut, Storrs, CT (United States); Morrison, Brian T. [Arizona State University, Tempe, AZ (United States); Dugger, Michael R. [Arizona State University, Tempe, AZ (United States); Ritchie, Barry G. [Arizona State University, Tempe, AZ (United States); Tucker, Ross J. [Arizona State University, Tempe, AZ (United States)

    2014-01-01

    Polarization observables are vital for disentangling overlapping resonances in the baryon spectrum. Extensive data have been collected at Jefferson Lab in Hall B with circularly and linearly polarized tagged photon beam incident on longitudinally polarized protons provided by the Frozen Spin Target (FROST). The focus of the described work is on ? photoproduction, which acts as an "isospin filter", isolating the N*(I = 1/2) resonances. Preliminary results for the double-polarization observables E and G are presented. There are currently no data on these in the world database for ? photoproduction.

  5. 16 Disturbance in Boreal Peatlands Merritt R. Turetsky and Vincent St. Louis

    E-Print Network [OSTI]

    Turetsky, Merritt

    ), largely owing to agricultural inten- sification, pollution, energy and forestry practices, and urban) pollution. Disturbance can be defined as discrete events in space and time that disrupt ecosystem structure

  6. 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.

    2015-04-01

    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$^2$.

  7. Measurement of the structure function of the nearly free neutron using spectator tagging in inelastic H2 ( e, e'ps ) X scattering with CLAS

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

    Tkachenko, S.; Baillie, N.; Kuhn, S. E.; Zhang, J.; Arrington, J.; Bosted, P.; Bültmann, S.; Christy, M. E.; Dutta, D.; Ent, R.; et al

    2014-04-24

    In this study, 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.

  8. 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; et al

    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.

  9. 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

    2014-04-01

    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.

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

    2015-04-01

    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

  11. Probabilistic Methods for Model Validation 

    E-Print Network [OSTI]

    Halder, Abhishek

    2014-05-01

    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...

  12. Scientists Mix Matter and Anti-Matter Results to Resolve Decade...

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

    Spectrometer, or CLAS, in Jefferson Lab's Experimental Hall B was used to measure electrons during the experiment. Fans of science and science fiction have been warned that...

  13. Is It or Isn't It? Pentaquark Debate Heats Up | Jefferson Lab

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

    Spectrometer (CLAS) collaboration took data with a high energy photon beam on a liquid hydrogen target. In a similar experiment conducted by the SAPHIR collaboration at...

  14. Mailing List Subscription

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

    egncalcom eightplus eightgev eng-div epicsusers farmsupport fel fewbody fsd g6clas guncntr gunwrk halbbpm halbbpmarchive hallldr halla hallamin hallaminarchive...

  15. Mailing List Subscription

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

    CEBAF Fast Shut Down System Back to Subscription Form G g6clas: No description available guncntr: Accelerator Gun Controls interest Group gunwrk: Accelerator Gun Controls working...

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

    E-Print Network [OSTI]

    Yeh, S. H; Lieberman, J. M

    2007-01-01

    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

  17. Purdue Hosts CAARMS9 - West Lafayette

    E-Print Network [OSTI]

    Sally

    2003-07-31

    ranging from hardware design, to algorithm design, to software design. What is quantum computing? In clas- sical computing, everything is well behaved.

  18. 2013 Research Opportunity Seed Fund Awards PI PI Dept, College CoPI(s) CoPI Dept, College Title

    E-Print Network [OSTI]

    Sin, Peter

    Studies; (2) School of Forest Resources & Conservation, IFAS; (3) Anthropology, CLAS; (4) Geography) Valérie de Crécy Lagard; (3) William B. Barbazuk (1) School of Forest Resources & Conservation

  19. Stress-intensity-factor influence coefficients for semielliptical inner-surface flaws in clad pressure vessels

    SciTech Connect (OSTI)

    Keeney, J.A.; Bryson, J.W.

    1995-12-31

    A problem of particular interest in pressure vessel technology is the calculation of accurate stress-intensity factors for semielliptical surface cracks in cylinders. Computing costs for direct solution techniques can be prohibitive when applied to three-dimensional (3-D) geometries with time-varying boundary conditions such as those associated with pressurized thermal shock. An alternative superposition technique requires the calculation of a set of influence coefficients for a given 3-D crack model that can be superimposed to obtain mode-I stress-intensity factors. This paper presents stress-intensity-factor influence coefficients (SIFICs) for axially and circumferentially oriented finite-length semielliptical inner-surface flaws with aspect ratios (total crack length (2c) to crack depth (a)) of 2, 6, and 10 for clad cylinders having an internal radius to wall thickness (t) ratio of 10. SIFICs are computed for flaw depths in the range of 0.01 {le} a/t {le} 0.5 and two cladding thicknesses. The incorporate of this SIFIC data base in fracture mechanics codes will facilitate the generation of fracture mechanics solutions for a wide range of flaw geometries as may be required in structural integrity assessments of pressurized-water and boiling-water reactors.

  20. Electroproduction of p?+?- [p pi superscript + pi superscript -] off protons at 0.2CLAS detector

    E-Print Network [OSTI]

    Rowntree, D.

    This paper reports on the most comprehensive data set obtained on differential and fully integrated cross sections for the process ep?e'p?+?- [ep?e prime p pi superscript + pi superscript -]. The data were collected with ...

  1. Two-For-One Confounds Physicists | Jefferson Lab

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

    Spectrometer, or CLAS, in Jefferson Lab's Experimental Hall B was used to measure electrons during the experiment. Ordinarily, getting two for the price of one is a great deal....

  2. 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

    2012-04-05

    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.

  3. Measurement of semi-inclusive pi(+) electroproduction off the proton

    E-Print Network [OSTI]

    Skabelin, Alexander V.

    Semi-inclusive ?+ [pi superscript +] electroproduction on protons has been measured with the CLAS detector at Jefferson Lab. The measurement was performed on a liquid-hydrogen target using a 5.75 GeV electron beam. The ...

  4. Photodisintegration of [superscript 4]He into p plus t

    E-Print Network [OSTI]

    Suleiman, R.

    The two-body photodisintegration of 4He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. Real photons produced with the ...

  5. NUMERICAL ANALYSIS OF THE CAHN-HILLIARD EQUATION AND APPROXIMATION FOR THE HELE-SHAW PROBLEM,

    E-Print Network [OSTI]

    that the super-index on the solution u is suppressed for notation brevity. We established a priori solution a global (in time) clas- sical solution. To our knowledge, such a numerical convergence result is not yet

  6. Learning to distinguish valid textual entailments Marie-Catherine de Marneffe, Bill MacCartney, Trond Grenager,

    E-Print Network [OSTI]

    Manning, Christopher

    critical for determining entailment. We propose a pipelined approach where alignment is followed by a clas Introduction In the area of textual inference, nearly all efforts have sought to extract the maximum mileage

  7. Learning to distinguish valid textual entailments MarieCatherine de Marneffe, Bill MacCartney, Trond Grenager,

    E-Print Network [OSTI]

    Pratt, Vaughan

    critical for determining entailment. We propose a pipelined approach where alignment is followed by a clas Introduction In the area of textual inference, nearly all efforts have sought to extract the maximum mileage

  8. Protons Hog the Momentum in Neutron-Rich Nuclei | U.S. DOE Office...

    Office of Science (SC) Website

    CEBAF Large Acceptance Spectrometer (CLAS), along with an event reconstructed from the data. In this experiment, an incident 5-GeV electron scatters from a nucleon (a proton or a...

  9. Ensemble Procedures for Finding High Risk Prison Inmates

    E-Print Network [OSTI]

    Richard A. Berk; Jong-Ho Baek

    2011-01-01

    Handbook for Evaluating Prison Clas- si?cations Systems. SanDi?erences in Predictors of Prison Violence: Assessing theInstitute of Corrections Prison Classi?cation Peer Training

  10. Medium modifications of the rho meson in nuclear photoproduction 

    E-Print Network [OSTI]

    Riek, F.; Rapp, Ralf; Oh, Yongseok; Lee, T. -S H.

    2010-01-01

    We extend our recent study of dilepton invariant-mass spectra from the decays of rho mesons produced by photon reactions off nuclei. We specifically focus on experimental spectra as recently measured by the CLAS Collaboration ...

  11. Measurement of the structure function of the nearly free neutron using spectator tagging in inelastic H2 ( e, e'ps ) X scattering with CLAS

    SciTech Connect (OSTI)

    Tkachenko, S.; Baillie, N.; Kuhn, S. E.; Zhang, J.; Arrington, J.; Bosted, P.; Bültmann, S.; Christy, M. E.; Dutta, D.; Ent, R.; Fenker, H.; Griffioen, K. A.; Ispiryan, M.; Kalantarians, N.; Keppel, C. E.; Melnitchouk, W.; Tvaskis, V.; Adhikari, K. P.; Aghasyan, M.; Amaryan, M. J.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Bedlinskiy, I.; Biselli, A. S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; 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.; Dodge, G. E.; Doughty, D.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fleming, J. A.; Garillon, B.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Golovatch, E.; Gothe, R. W.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hicks, K.; Ho, D.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jo, H. S.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; King, P. M.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuleshov, S. V.; Lenisa, P.; Lewis, S.; Livingston, K.; Lu, H.; MacCormick, M.; MacGregor, I. J. D.; Markov, N.; Mayer, M.; McKinnon, B.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moutarde, H.; Munoz Camacho, C.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Pasyuk, E.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Puckett, A. J. R.; Rimal, D.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Schott, D.; Schumacher, R. A.; Seder, E.; Senderovich, I.; Sharabian, Y. G.; Simonyan, A.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S.; Stepanyan, S. S.; Strauch, S.; Tang, W.; Ungaro, M.; Vlassov, A. V.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zana, L.; Zonta, I.

    2014-04-24

    In this study, 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. Hard Scattering Studies at Jlab

    SciTech Connect (OSTI)

    Harutyun Avagyan; Peter Bosted; Volker Burkert; Latifa Elouadrhiri

    2005-09-01

    We present current activities and future prospects for studies of hard scattering processes using the CLAS detector and the CEBAF polarized electron beam. Kinematic dependences of single and double spin asymmetries have been measured in a wide kinematic range at CLAS with a polarized NH{sub 3} and unpolarized liquid hydrogen targets. It has been shown that the data are consistent with factorization and observed target and beam asymmetries are in good agreement with measurements performed at higher energies, suggesting that the high energy-description of the semi-inclusive DIS process can be extended to the moderate energies of JLab measurements.

  13. 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

  14. University of Cambridge Department of Chemistry

    E-Print Network [OSTI]

    Middleton, Tom

    of Cambridge between October 1999 and March 2003. The contents are the original work of the author except where and Physical Sciences Research Council, and I also thank the National Lottery World Class Performance Fund, leading to a clas- si#12;cation of rearrangements in terms of those that contribute directly to di#11

  15. Building Decision Tree Classifier on Private Data Wenliang Du Zhijun Zhan

    E-Print Network [OSTI]

    Du, Wenliang "Kevin"

    Building Decision Tree Classifier on Private Data Wenliang Du Zhijun Zhan Center for Systems, Email: wedu,zhzhan@ecs.syr.edu Abstract This paper studies how to build a decision tree clas- sifier owned by Alice and the other piece owned by Bob. Alice and Bob want to build a decision tree classi

  16. Research Snapshot Third Quarter, Fiscal Year 2015 Awards by Quarter Awards Received Q3

    E-Print Network [OSTI]

    Bertini, Robert L.

    Decision Making; Department of Health and Human Services; $500,000; SSW; Renewal Cahn, Katharine; Leadership Academy for Middle Managers; Department of Health and Human Services; $428,351; SSW; Renewal Models in Variational Data Assimilation; Naval Research Laboratory; $163,284; CLAS; Amendment Daim

  17. On the True Y. CHARLES LI

    E-Print Network [OSTI]

    Li, Charles

    --for example, air and water. Fluid flows are clas- sified into two categories: laminar flow and turbulent flow. Laminar flow is smooth and mild, while turbulence is rough and violent. Because of the rough nature differential equations [12]. Fluid dynamicists believe that Navier-Stokes equations accurately describe

  18. 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

  19. Asynchronous vs Synchronous Input-Queued Switches

    E-Print Network [OSTI]

    Asynchronous vs Synchronous Input-Queued Switches Andrea Bianco, Davide Cuda, Paolo Giaccone, Fabio Neri Dipartimento di Elettronica, Politecnico di Torino (Italy) Abstract--Input-queued (IQ) switches are one of the reference architectures for the design of high-speed packet switches. Clas- sical results

  20. Submitted to ApJ; preprint: Jan 11, 2011. Inclination Mixing in the Classical Kuiper Belt

    E-Print Network [OSTI]

    Malhotra, Renu

    Submitted to ApJ; preprint: Jan 11, 2011. Inclination Mixing in the Classical Kuiper Belt Kathryn clas- sical and resonant Kuiper belt objects. This is partially motivated by the ob- served bimodal Kuiper belt undergo large changes in inclination (i > 5 ) over gigayear timescales, which means

  1. This interdisciplinary major combines courses in Anthropology, Classics, Art History, Linguistics, and Religion. It is ideal for students with an interest in how

    E-Print Network [OSTI]

    Leahy, Richard M.

    Abroad: Archaeology lends itself well to overseas studies. Spend a semester or year earning credit in locales as diverse as Jerusalem, Athens, or Santiago. Notable Courses AHIS 201: Digging into the Past Past CLAS 212: Archaeology -- Interpreting the Past AHIS 201: Digging into the Past -- Material

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

    SciTech Connect (OSTI)

    Iwamoto, Hideko [George Washington U.

    2011-08-01

    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.

  3. Transferable Utility Planning Games Ronen I. Brafman

    E-Print Network [OSTI]

    Engel, Yagil

    Transferable Utility Planning Games Ronen I. Brafman Computer Science Dept. Ben-Gurion Univ between standard AI planning constructs and a clas- sical cooperative model of transferable-utility coalition games, we introduce the notion of transferable-utility (TU) planning games. The key

  4. Multinomial Logistic Regression Ensembles This article proposes a method for multiclass classification problems using ensem-

    E-Print Network [OSTI]

    Ahn, Hongshik

    -dimensional data using the logistic regression model as a base clas- sifier. CERP is similar to random subspace (Ho classification problems using ensem- bles of multinomial logistic regression models. A multinomial logit model is used as a base classifier in ensembles from random partitions of predictors. The multinomial logit

  5. Nonlinear Radon and Fourier Transforms Franois Rouvire

    E-Print Network [OSTI]

    Vallette, Bruno

    Nonlinear Radon and Fourier Transforms François Rouvière Université de Nice Laboratoire Dieudonné, of the clas- sical Radon transform on hyperplanes. A function f on Rn can be reconstructed from nonlinear Radon transforms, obtained by integrating f and a ...nite num- ber of multiples x f over a family

  6. Wave-train-induced termination of weakly anchored vortices in excitable media Alain Pumir,1,2

    E-Print Network [OSTI]

    Sinha, Sitabhra

    , for the more general situation of pacing waves generated far away from the reentrant circuit, a clas- sicalWave-train-induced termination of weakly anchored vortices in excitable media Alain Pumir,1-8502, Japan 5 Nonlinear Physics and Math Modeling Laboratory, University Campus Bio-Medico, I-00128 Rome

  7. IN THIS ISSUE The Magazine for Alumni, Donors and

    E-Print Network [OSTI]

    Sin, Peter

    of Liberal Arts & Sciences, University of Florida Talkin' 'Bout My Regeneration 6 Chemistry Targets Cancer 20, that yields us the results that make our hearts sing." ­ Steve Jobs, Apple, Inc. CLAS Makes HOUSE Calls 28 Chemical Biology lab building. President Machen has stressed that chemistry is at the core of UF efforts

  8. Astronomy Reports, Vol. 40, No. 2, 1996. pp. 233--245. Translated from Astronomicheskii Zhurnal, Vol. 73, No. 2, 1996, pp. 259--272.

    E-Print Network [OSTI]

    in the model construction process. Comparison of parameters for a family of models having clas­ sical chemical of the seismic properties of the solar core for the set of models in question indicates that the best agreement these parameters to be reliably determined from oscillation analysis. 2. THE SEISMIC INFORMATION USED

  9. SGARFACE: a novel detector for microsecond gamma ray bursts

    E-Print Network [OSTI]

    SGARFACE: a novel detector for microsecond gamma ray bursts S. LeBohec *,1 , F. Krennrich, G surveys and monitors for clas- sical gamma ray bursts. The sensitivity of these telescopes is limited 2005 Abstract The Short GAmma Ray Front Air Cherenkov Experiment (SGARFACE) is operated at the Whipple

  10. Neutron Detection Efficiency of the

    E-Print Network [OSTI]

    Gilfoyle, Jerry

    Neutron Detection Efficiency of the CLAS12 Detector M. Moog and G. Gilfoyle University Of Richmond - Department of Physics Software We simulated the neutron detection efficiency of the forward time of flight scintillators for quasielastic electron-neutron scattering using a series of software packages. Elastic

  11. QUEEG: A Monte Carlo Event Generator for Quasielastic Scattering on Deuterium

    E-Print Network [OSTI]

    Gilfoyle, Jerry

    QUEEG: A Monte Carlo Event Generator for Quasielastic Scattering on Deuterium G.P. Gilfoyle1 , J. Examples of the use of the event generator are shown. The source and Makefiles are available in the CLAS12 an event generator for quasielastic scattering off nucleons in deuterium. This work was motivated

  12. A new framebased statistical strategy for bird migration clutter removal in wind profiler radar data

    E-Print Network [OSTI]

    Teschke, Gerd

    A new frame­based statistical strategy for bird migration clutter removal in wind profiler radar clutter removal routine for wind profiler radar data. The basic idea is to put together already existing of the expansion. A Relaxation of the clas- sical constraint T = 2 generates a crucial degree of freedom

  13. 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

  14. arXiv:cs.DB/0206023v115Jun2002 Relational Association Rules

    E-Print Network [OSTI]

    Antwerpen, Universiteit

    Van den Bussche University of Limburg, Belgium Abstract In recent years, the problem of association rule mining in transactional data has been well studied. We propose to extend the discovery of clas and pruning operators. 1 Introduction In recent years, the problem of mining association rules over frequent

  15. A phenomenological study on the $\\cos\\phi_h$ azimuthal asymmetry in double longitudinally Polarized SIDIS

    E-Print Network [OSTI]

    Mao, Wenjuan; Du, Xiaozhen; Lu, Zhun; Ma, Bo-Qiang

    2015-01-01

    We study the $\\cos{\\phi_h}$ azimuthal asymmetry in double polarized semi-inclusive pion production by considering dynamical twist-3 effects. In particular, we evaluate the role of the transverse momentum dependent distributions $e_L(x, k_T^2)$ and $g_L^\\perp(x, k_T^2)$ on the asymmetry. Using two different sets of spectator model results for these distributions, we predict the $\\cos{\\phi_h}$ asymmetry of $\\pi^+$, $\\pi^-$, and $\\pi^0$ at the kinematic configuration available at CLAS, HERMES and COMPASS. Our estimates show that the asymmetries are positive for all the pions and could be accessed by CLAS and HERMES. We also find that $g_L^\\perp$ gives the dominant contribution to the $\\cos\\phi_h$ asymmetry, while the contribution of $e_L$ is almost negligible.

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

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

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

    2012-03-01

    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

  17. 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'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

    2012-03-23

    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

    E-Print Network [OSTI]

    I. I. Strakovsky; W. Chen; H. Gao; W. J. Briscoe; D. Dutta; A. E. Kudryavtsev; M. Mirazite; M. Paris; P. Rossi; S. Stepanyan; V. E. Tarasov; R. L. Workman

    2012-08-05

    We report a new extraction of nucleon resonance couplings using pi- photoproduction cross sections on the neutron. The world database for the process gn-->pi-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 piN 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. Single and double polarization asymmetries from deeply virtual exclusive pi^0 electroproduction

    SciTech Connect (OSTI)

    Kim, Andrey; Avakian, Harut A.; Burkert, Volker D.

    2014-10-01

    The target and double spin asymmetry measurements of exclusive p0 electroproduction were performed for the first time in DIS region at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS) and longitudinally polarized proton target. The wide kinematic coverage and good resolution of CLAS allowed measurements in full azimuthal range providing an opportunity to extract single and double spin asymmetries proportional to polarized structure functions. Their angular dependencies in hadronic center-of-mass system were analyzed, and extracted moments are compared to recent theoretical handbag-based calculations based on chiral-even and chiral-odd GPDs contributions. The interpretation of present results within the framework of the modified perturbative approach and their use as a constraint for models of the t behavior will be discussed.

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

    SciTech Connect (OSTI)

    Kageya, Tsuneo

    2014-01-01

    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.

  1. Measurements of spin observables in pseudo-scalar meson photo-production using polarized neutrons in solid HD

    SciTech Connect (OSTI)

    Kageya, Tsuneo

    2014-01-01

    A measurement of psuedo-scalar meson photo production from longitudinally polarized solid HD has been carried out with the CLAS at Thomas Jefferson National Accelerator Facility (Jlab) with circularly and linearly polarized photon beams. Its aim is to measure a complete set of spin observables for the neutron simultaneously from the same experiment. As a polarized neutron, deutron in HD was used. Preliminary asymmetries are shown for the {pi}{sup -} channel.

  2. Studies of transverse spin effects at Jlab

    SciTech Connect (OSTI)

    Harutyun Avakian; Peter Bosted; Volker Burkert; Latifa Elouadrhiri

    2006-06-01

    We present ongoing and future studies of single-spin asymmetries in semi-inclusive electroproduction of pions using the CEBAF polarized electron beam. Kinematic dependences of single-spin asymmetries have been measured in a wide kinematic range at CLAS with a polarized NH{sub 3} target. Significant target-spin sin 2{phi} and sin {phi} asymmetries have been observed, indicating a non-zero Collins fragmentation function and supporting future SIDIS measurements with upgraded JLab.

  3. 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)

    2014-01-01

    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.

  4. Detecting Networks Employing Algorithmically Generated Domain Names 

    E-Print Network [OSTI]

    Ashwath Kumar Krishna Reddy

    2011-10-21

    , current botnets use simple pseudo-random generators which may not preserve the distribution of alphabets or bigrams (two consecutive alphabets) as usually occur in legitimate domain name strings. In this regards, we propose several metrics to classify a... generates. For instance, in the extreme scenario that a botnet generates 50 domains mapped to the same TLD, we show that KL-divergence over unigrams achieves 100% detection accuracy albeit at 15% false positive rate (legitimate domain groups clas- 7 si ed...

  5. Polarization Measurements in Photoproduction with CEBAF Large Acceptance Spectrometer

    SciTech Connect (OSTI)

    E. Pasyuk

    2010-05-01

    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.

  6. Texas A & M University-Central Texas Department ofPsychology and Counseling

    E-Print Network [OSTI]

    Diestel, Geoff

    Texas A & M University- Central Texas Department ofPsychology and Counseling CPSY 551.110 Career Counseling and Guidance Fall2011 Dr. Pauline S. Moseley Texas A & M University -Central Texas- North Campus and Wednesday 2:00-5:00 pm; Thursday 2:00-4:00 pm Clas Time: W 6:00pm-8:50pm Texas A & M University- Central

  7. The $K^{\\ast 0}\\Lambda$ photoproduction off a neutron

    E-Print Network [OSTI]

    Wan, Xiao-Yun

    2015-01-01

    Inspired by the preliminary experimental data by the CLAS Collaboration, the $K^{\\ast 0}\\Lambda$ photoproduction off a neutron is studied within an effective Lagrangian approach. The contributions from the Born terms including $s$, $u$, and $t$ channels are considered to calculate the amplitude, with which the cross sections are calculated and compared with preliminary CLAS data. The theoretical results indicate that the contribution from the $K$-exchange $t$ channel plays a dominant role for the $K^{\\ast 0}\\Lambda$ photoproduction. The contribution from the $\\kappa$ exchange is found one order of magnitude smaller than that from $K$ exchange. Both the Regge model and the Feynman model are applied to treat the $t$-channel contribution. The discrepancy between two models is found small in the energy range of CLAS data and predicted to become obvious at energies higher than 3 GeV. More precise experimental data especially at backward angles will be helpful to further understand the interaction mechanism of the ...

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

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

    Aghasyan, M.; Avakian, H.; Rossi, P.; De Sanctis, E.; Hasch, D.; Mirazita, M.; Adikaram, D.; Amaryan, M. J.; Anghinolfi, M.; Baghdasaryan, H.; et al

    2011-10-01

    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.

  9. Strangeness suppression of qq¯ creation observed in exclusive reactions

    SciTech Connect (OSTI)

    Mestayer, M. D.; Park, K.; Adhikari, K. P.; Aghasyan, M.; Pereira, S. Anefalos; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; 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.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; Alaoui, A. El; Fassi, L. El; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fleming, J. A.; Forest, T. A.; Garillon, B.; Garçon, M.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Hakobyan, H.; Hanretty, C.; Hattawy, M.; Holtrop, M.; Hughes, S. M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Jiang, H.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Koirala, S.; Kubarovsky, V.; Kuleshov, S. V.; Lenisa, P.; Levine, W. I.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Mayer, M.; McKinnon, B.; Meyer, C. A.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moody, C. I.; Moutarde, H.; Movsisyan, A.; Camacho, C. Munoz; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Peng, P.; Phelps, W.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Protopopescu, D.; Puckett, A. J. R.; Raue, B. A.; Rimal, D.; Ripani, M.; Rizzo, A.; Rosner, G.; Roy, P.; Sabatié, F.; Saini, M. S.; Schott, D.; Schumacher, R. A.; Simonyan, A.; Sokhan, D.; Strauch, S.; Sytnik, V.; Tang, W.; Tian, Ye; Ungaro, M.; Vernarsky, B.; Vlassov, A. V.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zhang, J.; Zhao, Z. W.; Zonta, I.

    2014-10-10

    In this study, 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.

  10. Strangeness Suppression of qq- Creation Observed in Exclusive Reactions

    SciTech Connect (OSTI)

    Mestayer, M.? D.; Park, K.; Adhikari, K.? P.; Aghasyan, M.; Pereira, S. Anefalos; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A.? S.; Boiarinov, S.; Briscoe, W.? J.; Brooks, W.? K.; Burkert, V.? D.; 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.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; Alaoui, A.? El; Fassi, L.? El; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fleming, J. ?A.; Forest, T.? A.; Garillon, B.; Garçon, M.; Ghandilyan, Y.; Gilfoyle, G. ?P.; Giovanetti, K. ?L.; Girod, F. ?X.; Goetz, J.? T.; Golovatch, E.; Gothe, R. W.; Griffioen, K.? A.; Guegan, B.; Guidal, M.; Hakobyan, H.; Hanretty, C.; Hattawy, M.; Holtrop, M.; Hughes, S.? M.; Hyde, C.?. E; Ilieva, Y.; Ireland, D.?. G; Jiang, H.; Jo, H.? S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Koirala, S.; Kubarovsky, V.; Kuleshov, S. ?V.; Lenisa, P.; Levine, W. ?I.; Livingston, K.; Lu, H.? Y.; MacGregor, I.? J.?D.; Mayer, M.; McKinnon, B.; Meyer, C.? A.; Mirazita, M.; Mokeev, V.; Montgomery, R.? A.; Moody, C.? I.; Moutarde, H.; Movsisyan, A.; Camacho, C. Munoz; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A.? I.; Pappalardo, L.? L.; Paremuzyan, R.; Peng, P.; Phelps, W.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J.? W.; Protopopescu, D.; Puckett, A.? J.?R.; Raue, B.? A.; Rimal, D.; Ripani, M.; Rizzo, A.; Rosner, G.; Roy, P.; Sabatié, F.; Saini, M.?. S; Schott, D.; Schumacher, R.? A.; Simonyan, A.; Sokhan, D.; Strauch, S.; Sytnik, V.; Tang, W.; Tian, Ye; Ungaro, M.; Vernarsky, B.; Vlassov, A.? V.; Voskanyan, H.; Voutier, E.; Walford, N.? K.; Watts, D.? P.; Wei, X.; Weinstein, L.? B.; Wood, M.? H.; Zachariou, N.; Zhang, J.; Zhao, Z.? W.; Zonta, I.

    2014-10-01

    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.

  11. U-spin predictions of the transition magnetic moments of the electromagnetic decay of the {Sigma}{sup ?}(1385) baryons

    SciTech Connect (OSTI)

    Keller, Dustin M. [University of Virginia; Hicks, Kenneth H. [OHIO

    2013-05-01

    The transition magnetic moments for decuplet-to-octet baryon electromagnetic decays are calculated from the CLAS experimental results and are compared with calculations to first order in the 1/N{sub c} expansion of quantum chromodynamics (QCD) and new U-spin predictions. Using the U-spin predictions for the {Sigma} *{sup 0} --> {Sigma}{sup 0} {gamma} and {Sigma} *{sup +} ? {Sigma}{sup +} {gamma} decays, the SU(3)-forbidden transition {Sigma} *{sup -} ? {Sigma}{sup -} {gamma} is obtained. In addition, the doubly strange baryon radiative decay {Xi} *{sup 0} ? {Xi} {gamma} is predicted using U-spin.

  12. Electromagnetic production of hyperon resonances

    E-Print Network [OSTI]

    K. Hicks; D. Keller; W. Tang

    2010-12-14

    The study of hyperon resonances has entered a new era of precision with advent of high-statistics photoproduction data from the CLAS detector at Jefferson Lab. These data have multi-particle final states, allowing clean identification of exclusive reactions associated with strange mesons and baryons. Examples of physics results are: evidence for isospin interference in the decay of the $\\Lambda(1405)$ resonance; a strong suggestion of meson cloud effects in the structure of the $\\Sigma(1385)$ resonance; data from $K^*$ photoproduction that will test the existence of the purported $K_0(800)$ meson. Properties of other hyperon resonances will also be studied in the near future.

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

    SciTech Connect (OSTI)

    Celentano, Andrea

    2014-06-01

    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.

  14. 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

    2009-10-19

    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.

  15. Spin Sum Rules and the Strong Coupling Constant at large distance

    E-Print Network [OSTI]

    A. Deur

    2009-06-23

    We present recent results on the Bjorken and the generalized forward spin polarizability sum rules from Jefferson Lab Hall A and CLAS experiments, focusing on the low $Q^2$ part of the measurements. We then discuss the comparison of these results with Chiral Perturbation theory calculations. In the second part of this paper, we show how the Bjorken sum rule with its connection to the Gerasimov-Drell-Hearn sum, allows us to conveniently define an effective coupling for the strong force at all distances.

  16. Mainstreaming New Renewable Energy Technologies

    E-Print Network [OSTI]

    Neuhoff, Karsten; Sellers, Rick

    , education, and communication, can significantly enhance energy access (Johansson et al., 2004b). 1 7 7.1 Short-term weather forecasts The electricity system requires a permanent match be tween demand and supply. It must keep sufficient generation... , (Wene, Clas O tto) Experience Curves for Energy Technology Policy, Paris, 2000. 5 In some off-grid applications, P.V. is already cost competitive with conventional technologies. The off-grid market is growing at 16% per year (1992-2002) but is too...

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

    SciTech Connect (OSTI)

    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.

    2012-01-30

    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.

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

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

    Moriya, Kei; Schumacher, Reinhard A.

    2014-02-28

    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 c.m.K++ polarized such that the ?(1405) has spin-parity JP=1/2-, as expected by most theories.

  19. 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.; et al

    2012-01-30

    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.

  20. Strangeness suppression of qq¯ creation observed in exclusive reactions

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

    Mestayer, M. D.; Park, K.; Adhikari, K. P.; Aghasyan, M.; Pereira, S. Anefalos; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; et al

    2014-10-10

    In this study, 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.

  1. Extracting meson-baryon contributions to the electroexcitation of the N (1675)-5/2 nucleon resonance

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

    Aznauryan, Inna G.; Burkert, Volker D.

    2015-07-01

    We report on the determination of the electrocouplings for the transition from the proton to the N (1675)-5/2 resonance state using recent differential cross section data on ep ? e?+n by the CLAS collaboration at 1.8 ? Q² -5/2 helicity amplitudes show considerable coupling through the AP1/2 amplitude, that is significantly larger than predicted three-quark contribution to this amplitude. The amplitude AP3/2 is much smaller. Both results are consistent with the predicted sizes of the meson-baryonmore »contributions at Q² ? 1.8 GeV² from the dynamical coupled-channel model.« less

  2. 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)

    2014-05-01

    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.

  3. 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.; Meyer, C. A.; Bellis, M.; Williams, M.; Adhikari, K. P.; Adikaram, D.; Aghasyan, M.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; et al

    2014-05-27

    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 themore »?. 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.« less

  4. 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.

    2015-05-01

    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

  5. 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

    2010-12-14

    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.

  6. 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

    2014-04-24

    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.

  7. 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

    2012-03-26

    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

  8. 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

    2015-01-01

    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.

  9. 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

    2015-04-07

    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.

  10. Differential Photoproduction Cross Sections of the Sigma0(1385), Lambda(1405), and Lambda(1520)

    SciTech Connect (OSTI)

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

    2013-10-01

    We report the exclusive photoproduction cross sections for the Sigma(1385), Lambda(1405), and Lambda(1520) in the reactions gamma + p -> K+ + Y* using the CLAS detector for energies from near the respective production thresholds up to a center-of-mass energy W of 2.85 GeV. The differential cross sections are integrated to give the total exclusive cross sections for each hyperon. Comparisons are made to current theoretical models based on the effective Lagrangian approach and fitted to previous data. The accuracy of these models is seen to vary widely. The cross sections for the Lambda(1405) region are strikingly different for the Sigma+pi-, Sigma0 pi0, and Sigma- pi+ decay channels, indicating the effect of isospin interference, especially at W values close to the threshold.

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

    SciTech Connect (OSTI)

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

    2014-02-01

    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

  12. Observation of a backward peak in the gamma d ---> pi0 d cross- section near the eta threshold

    SciTech Connect (OSTI)

    Yordanka Ilieva; Barry Berman; Alexander Kudryavtsev; I.I. Strakovsky; V.E. Tarasov; Moscov Amaryan; Pawel Ambrozewicz; Marco Anghinolfi; G. Asryan; Harutyun Avakian; Hovhannes Baghdasaryan; Nathan Baillie; Jacques Ball; Nathan Baltzell; V. Batourine; Marco Battaglieri; Ivan Bedlinski; Ivan Bedlinskiy; Matthew Bellis; Nawal Benmouna; Angela Biselli; Sylvain Bouchigny; Sergey Boyarinov; Robert Bradford; Derek Branford; William Briscoe; William Brooks; Stephen Bueltmann; Volker Burkert; Cornel Butuceanu; John Calarco; Sharon Careccia; Daniel Carman; Shifeng Chen; Philip Cole; Patrick Collins; Philip Coltharp; Donald Crabb; Volker Crede; R. De Masi; Enzo De Sanctis; Raffaella De Vita; Pavel Degtiarenko; Alexandre Deur; Richard Dickson; Chaden Djalali; Gail Dodge; Joseph Donnelly; David Doughty; Michael Dugger; Oleksandr Dzyubak; Hovanes Egiyan; Kim Egiyan; Latifa Elouadrhiri; Paul Eugenio; Gleb Fedotov; Gerald Feldman; Herbert Funsten; Michel Garcon; Gagik Gavalian; Gerard Gilfoyle; Kevin Giovanetti; Francois-Xavier Girod; John Goetz; Atilla Gonenc; Ralf Gothe; Keith Griffioen; Michel Guidal; Nevzat Guler; Lei Guo; Vardan Gyurjyan; Kawtar Hafidi; Rafael Hakobyan; F. Hersman; Kenneth Hicks; Ishaq Hleiqawi; Maurik Holtrop; Charles Hyde; Charles Hyde-Wright; David Ireland; Boris Ishkhanov; Eugeny Isupov; Mark Ito; David Jenkins; Hyon-Suk Jo; Kyungseon Joo; Henry Juengst; Narbe Kalantarians; James Kellie; Mahbubul Khandaker; Wooyoung Kim; Andreas Klein; Franz Klein; Mikhail Kossov; Zebulun Krahn; Laird Kramer; V. Kubarovsky; Joachim Kuhn; Sebastian Kuhn; Sergey Kuleshov; Jeff Lachniet; Jean Laget; Jorn Langheinrich; David Lawrence; Kenneth Livingston; Haiyun Lu; Marion MacCormick; Nikolai Markov; Bryan McKinnon; Bernhard Mecking; Mac Mestayer; Curtis Meyer; Tsutomu Mibe; Konstantin Mikhaylov; Marco Mirazita; Rory Miskimen; Viktor Mokeev; Kei Moriya; Steven Morrow; M. Moteabbed; E. Munevar; Gordon Mutchler; Pawel Nadel-Turonski; Rakhsha Nasseripour; Silvia Niccolai; Gabriel Niculescu; Maria-Ioana Niculescu; Bogdan Niczyporuk; Megh Niroula; Rustam Niyazov; Mina Nozar; Mikhail Osipenko; Alexander Ostrovidov; K. Park; Evgueni Pasyuk; Craig Paterson; Joshua Pierce; Nikolay Pivnyuk; Oleg Pogorelko; S. Pozdniakov; John Price; Yelena Prok; Dan Protopopescu; Brian Raue; Giovanni Ricco; Marco Ripani; Barry Ritchie; Federico Ronchetti; Guenther Rosner; Patrizia Rossi; Franck Sabatie; Carlos Salgado; Joseph Santoro; Vladimir Sapunenko; Reinhard Schumacher; Vladimir Serov; Youri Sharabian; Nikolay Shvedunov; Elton Smith; Lee Smith; Daniel Sober; Aleksey Stavinskiy; Samuel Stepanyan; Stepan Stepanyan; Burnham Stokes; Paul Stoler; Steffen Strauch; Mauro Taiuti; David Tedeschi; Ulrike Thoma; Avtandil Tkabladze; Svyatoslav Tkachenko; Clarisse Tur; Maurizio Ungaro; Michael Vineyard; Alexander Vlassov; Lawrence Weinstein; Dennis Weygand; M. Williams; Elliott Wolin; Michael Wood; Amrit Yegneswaran; Lorenzo Zana; Jixie Zhang; Bo Zhao; Zhiwen Zhao

    2007-05-14

    High-quality cross sections for the reaction gamma+d->pi^0+d have been measured using the CLAS at Jefferson Lab over a wide energy range near and above the eta-meson photoproduction threshold. At backward c.m. angles for the outgoing pions, we observe a resonance-like structure near E_gamma=700 MeV. Our model analysis shows that it can be explained by eta excitation in the intermediate state. The effect is the result of the contribution of the N(1535)S_11 resonance to the amplitudes of the subprocesses occurring between the two nucleons and of a two-step process in which the excitation of an intermediate eta meson dominates.

  13. Light Vector Mesons in the Nuclear Medium

    SciTech Connect (OSTI)

    Wood, Michael; Nasseripour, Rakhsha; Weygand, Dennis; Djalali, Chaden; Tur, Clarisse; Mosel, Ulrich; Muehlich, Pascal; Adams, Gary; Amaryan, Moscov; Amaryan, Moskov; Ambrozewicz, Pawel; Anghinolfi, Marco; Asryan, Gegham; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Baillie, Nathan; Ball, James; Baltzell, Nathan; Barrow, Steve; Battaglieri, Marco; Bedlinskiy, Ivan; Bektasoglu, Mehmet; Bellis, Matthew; Benmouna, Nawal; Berman, Barry; Biselli, Angela; Blaszczyk, Lukasz; Bouchigny, Sylvain; Boyarinov, Sergey; Bradford, Robert; Branford, Derek; Briscoe, William; Brooks, William; Burkert, Volker; Butuceanu, Cornel; Calarco, John; Careccia, Sharon; Carman, Daniel; Carnahan, Bryan; Casey, Liam; Chen, Shifeng; Cheng, Lu; Cole, Philip; Collins, Patrick; Coltharp, Philip; Crabb, Donald; Crannell, Hall; Crede, Volker; Cummings, John; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Degtiarenko, Pavel; Denizli, Haluk; Dennis, Lawrence; Deur, Alexandre; Dharmawardane, Kahanawita; Dickson, Richard; Dodge, Gail; Doughty, David; Dugger, Michael; Dytman, Steven; Dzyubak, Oleksandr; Egiyan, Hovanes; Egiyan, Kim; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Feldman, Gerald; Feuerbach, Robert; Fradi, Ahmed; Funsten, Herbert; Garcon, Michel; Gavalian, Gagik; Gilfoyle, Gerard; Giovanetti, Kevin; Girod, Francois-Xavier; Goetz, John; Gordon, Christopher; Gothe, Ralf; Griffioen, Keith; Guidal, Michel; Guler, Nevzat; Guo, Lei; Gyurjyan, Vardan; Hadjidakis, Cynthia; Hafidi, Kawtar; Hakobyan, Hayk; Hakobyan, Rafael; Hanretty, Charles; Hardie, John; Hassall, Neil; Hersman, F.; Hicks, Kenneth; Hleiqawi, Ishaq; Holtrop, Maurik; Hyde, Charles; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Ito, Mark; Jenkins, David; Jo, Hyon-Suk; Johnstone, John; Joo, Kyungseon; Juengst, Henry; Kalantarians, Narbe; Kellie, James; Khandaker, Mahbubul; Khetarpal, Puneet; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Klimenko, Alexei; Kossov, Mikhail; Krahn, Zebulun; Kramer, Laird; Kubarovsky, Valery; Kuhn, Joachim; Kuhn, Sebastian; Kuleshov, Sergey; Lachniet, Jeff; Laget, Jean; Langheinrich, Jorn; Lawrence, David; Li, Ji; Livingston, Kenneth; Lu, Haiyun; MacCormick, Marion; Markov, Nikolai; Mattione, Paul; McAleer, Simeon; McKinnon, Bryan; McNabb, John; Mecking, Bernhard; Mehrabyan, Surik; Melone, Joseph; Mestayer, Mac; Meyer, Curtis; Mibe, Tsutomu; Mikhaylov, Konstantin; Minehart, Ralph; Mirazita, Marco; Miskimen, Rory; Mokeev, Viktor; Moriya, Kei; Morrow, Steven; Moteabbed, Maryam; Mueller, James; Munevar Espitia, Edwin; Mutchler, Gordon; Nadel-Turonski, Pawel; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria-Ioana; Niczyporuk, Bogdan; Niroula, Megh; Niyazov, Rustam; Nozar, Mina; Osipenko, Mikhail; Ostrovidov, Alexander; Park, Kijun; Pasyuk, Evgueni; Paterson, Craig; Pereira, Sergio; Pierce, Joshua; Pivnyuk, Nikolay; Pocanic, Dinko; Pogorelko, Oleg; Pozdnyakov, Sergey; Preedom, Barry; Price, John; Prok, Yelena; Protopopescu, Dan; Raue, Brian; Riccardi, Gregory; Ricco, Giovanni; Ripani, Marco; Ritchie, Barry; Ronchetti, Federico; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Salamanca, Julian; Salgado, Carlos; Santoro, Joseph; Sapunenko, Vladimir; Schumacher, Reinhard; Serov, Vladimir; Sharabian, Youri; Sharov, Dmitri; Shvedunov, Nikolay; Smith, Elton; Smith, Lee; Sober, Daniel; Sokhan, Daria; Stavinsky, Aleksey; Stepanyan, Stepan; Stepanyan, Samuel; Stokes, Burnham; Stoler, Paul; Strakovski, Igor; Strauch, Steffen; Taiuti, Mauro; Tedeschi, David; Tkabladze, Avtandil; Tkachenko, Svyatoslav; Todor, Luminita; Ungaro, Maurizio; Vineyard, Michael; Vlassov, Alexander; Watts, Daniel; Weinstein, Lawrence; Williams, Michael; Wolin, Elliott; Yegneswaran, Amrit; Zana, Lorenzo; Zhang, Bin; Zhang, Jixie; Zhao, Bo; Zhao, Zhiwen

    2008-07-01

    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 eff

  14. First measurement of coherent $\\phi$-meson photoproduction on deuteron at low energies

    SciTech Connect (OSTI)

    Tsutomu Mibe; Haiyan Gao; Kenneth Hicks; Kevin Kramer; Stepan Stepanyan; David Tedeschi; Moscov Amaryan; Pawel Ambrozewicz; Marco Anghinolfi; G. Asryan; Gerard Audit; Harutyun Avakian; Hovhannes Baghdasaryan; Nathan Baillie; Jacques Ball; Nathan Baltzell; Marco Battaglieri; Ivan Bedlinski; Ivan Bedlinskiy; Matthew Bellis; Nawal Benmouna; Barry Berman; Angela Biselli; Lukasz Blaszczyk; Sylvain Bouchigny; Sergey Boyarinov; Robert Bradford; Derek Branford; William Briscoe; William Brooks; Stephen Bueltmann; Volker Burkert; Cornel Butuceanu; John Calarco; Sharon Careccia; Daniel Carman; Shifeng Chen; Philip Cole; Patrick Collins; Philip Coltharp; Donald Crabb; Hall Crannell; Volker Crede; John Cummings; Natalya Dashyan; Rita De Masi; Raffaella De Vita; Enzo De Sanctis; Pavel Degtiarenko; Alexandre Deur; Kahanawita Dharmawardane; Richard Dickson; Chaden Djalali; Gail Dodge; Joseph Donnelly; David Doughty; Michael Dugger; Oleksandr Dzyubak; Hovanes Egiyan; Kim Egiyan; Lamiaa Elfassi; Latifa Elouadrhiri; Paul Eugenio; Gleb Fedotov; Gerald Feldman; Herbert Funsten; Michel Garcon; Gagik Gavalian; Gerard Gilfoyle; Kevin Giovanetti; Francois-Xavier Girod; John Goetz; Atilla Gonenc; Christopher Gordon; Ralf Gothe; Keith Griffioen; Michel Guidal; Nevzat Guler; Lei Guo; Vardan Gyurjyan; Cynthia Hadjidakis; Kawtar Hafidi; Hayk Hakobyan; Rafael Hakobyan; Charles Hanretty; John Hardie; F. Hersman; Ishaq Hleiqawi; Maurik Holtrop; Charles Hyde; Charles Hyde-Wright; Yordanka Ilieva; David Ireland; Boris Ishkhanov; Eugeny Isupov; Mark Ito; David Jenkins; Hyon-Suk Jo; John Johnstone; Kyungseon Joo; Henry Juengst; Narbe Kalantarians; James Kellie; Mahbubul Khandaker; Wooyoung Kim; Andreas Klein; Franz Klein; Alexei Klimenko; Mikhail Kossov; Zebulun Krahn; Laird Kramer; V. Kubarovsky; Joachim Kuhn; Sebastian Kuhn; Sergey Kuleshov; Viacheslav Kuznetsov; Jeff Lachniet; Jean Laget; Jorn Langheinrich; David Lawrence; Tsung-shung Lee; Ji Li; Kenneth Livingston; Haiyun Lu; Marion MacCormick; Claude Marchand; Nikolai Markov; Paul Mattione; Bryan McKinnon; Bernhard Mecking; Joseph Melone; Mac Mestayer; Curtis Meyer; Konstantin Mikhaylov; Ralph Minehart; Marco Mirazita; Rory Miskimen; Viktor Mokeev; Kei Moriya; Steven Morrow; M. Moteabbed; E. Munevar; Gordon Mutchler; P. Nadel-Turonski; Rakhsha Nasseripour; Silvia Niccolai; Gabriel Niculescu; Maria-Ioana Niculescu; Bogdan Niczyporuk; Megh Niroula; Rustam Niyazov; Mina Nozar; Mikhail Osipenko; Alexander Ostrovidov; K. Park; Evgueni Pasyuk; Craig Paterson; S. Anefalos Pereira; Joshua Pierce; Nikolay Pivnyuk; Dinko Pocanic; Oleg Pogorelko; S. Pozdniakov; John Price; Yelena Prok; Dan Protopopescu; Brian Raue; Gregory Riccardi; Giovanni Ricco; Marco Ripani; Barry Ritchie; Federico Ronchetti; Guenther Rosner; Patrizia Rossi; Franck Sabatie; Julian Salamanca; Carlos Salgado; Joseph Santoro; Vladimir Sapunenko; Reinhard Schumacher; Vladimir Serov; Youri Sharabian; Dmitri Sharov; Nikolay Shvedunov; Elton Smith; Lee Smith; Daniel Sober; Daria Sokhan; A. Stavinsky; Samuel Stepanyan; B.E. Stokes; Paul Stoler; I.I. Strakovsky; Steffen Strauch; Mauro Taiuti; Ulrike Thoma; Avtandil Tkabladze; Svyatoslav Tkachenko; Luminita Todor; Clarisse Tur; Maurizio Ungaro; Michael Vineyard; Alexander Vlassov; Daniel Watts; Lawrence Weinstein; Dennis Weygand; M. Williams; Elliott Wolin; Michael Wood; Amrit Yegneswaran; Lorenzo Zana; Jixie Zhang; Bo Zhao; Zhiwen Zhao

    2007-11-01

    The cross section and decay angular distributions for the coherent \\phi meson photoproduction on the deuteron have been measured for the first time up to a squared four-momentum transfer t =(p_{\\gamma}-p_{\\phi})^2 =-2 GeV^2/c^2, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cross sections are compared with predictions from a re-scattering model. In a framework of vector meson dominance, the data are consistent with the total \\phi-N cross section \\sigma_{\\phi N} at about 10 mb. If vector meson dominance is violated, a larger \\sigma_{\\phi N} is possible by introducing larger t-slope for the \\phi N \\to \\phi N process than that for the \\gamma N \\to \\phi N process. The decay angular distributions of the \\phi are consistent with helicity conservation.

  15. Measurement of ep-->ep[pi]0 beam spin asymmetries above the resonance region

    SciTech Connect (OSTI)

    De Masi, Rita; Garcon, Michel; Zhao, Bo; Amaryan, Moscov; Amaryan, Moskov; Ambrozewicz, Pawel; Anghinolfi, Marco; Asryan, Gegham; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Baillie, Nathan; Ball, J.P.; Ball, Jacques; Ball, J.P.; Ball, Jacques; Ball, James; Baltzell, Nathan; Baturin, Vitaly; Battaglieri, Marco; Bedlinskiy, Ivan; Bellis, Matthew; Benmouna, Nawal; Berman, Barry; Bertin, Pierre; Biselli, Angela; Blaszczyk, Lukasz; Bouchigny, Sylvain; Boyarinov, Sergey; Bradford, Robert; Branford, Derek; Briscoe, William; Brooks, William; Bultmann, S.; Bueltmann, Stephen; Bultmann, S.; Bueltmann, Stephen; Burkert, Volker; Butuceanu, Cornel; Calarco, John; Careccia, Sharon; Carman, Daniel; Casey, Liam; Chen, Shifeng; Cheng, Lu; Cole, Philip; Collins, Patrick; Coltharp, Philip; Crabb, Donald; Crede, Volker; Dashyan, Natalya; De Sanctis, Enzo; De Vita, Raffaella; Degtiarenko, Pavel; Deur, Alexandre; Dharmawardane, Kahanawita; Dickson, Richard; Djalali, Chaden; Dodge, Gail; Donnelly, Joseph; Doughty, David; Dugger, Michael; Dzyubak, Oleksandr; Egiyan, Hovanes; Egiyan, Kim; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Feldman, Gerald; Fradi, Ahmed; Funsten, Herbert; Gavalian, Gagik; Gilfoyle, Gerard; Giovanetti, Kevin; Girod, Francois-Xavier; Goetz, John; Gonenc, Atilla; Gothe, Ralf; Griffioen, Keith; Guidal, Michel; Guler, Nevzat; Guo, Lei; Gyurjyan, Vardan; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Hersman, F.; Hicks, Kenneth; Hleiqawi, Ishaq; Holtrop, Maurik; Hyde, Charles; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Ito, Mark; Jenkins, David; Jo, Hyon-Suk; Johnstone, John; Joo, Kyungseon; Juengst, Henry; Kalantarians, Narbe; Kellie, James; Khandaker, Mahbubul; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Klimenko, Alexei; Kossov, Mikhail; Krahn, Zebulun; Kramer, Laird; Kubarovsky, Valery; Kuhn, Joachim; Kuhn, Sebastian; Kuleshov, Sergey; Lachniet, Jeff; Laget, Jean; Langheinrich, Jorn; Lawrence, David; Lee, Tsung-Shung; Livingston, Kenneth; Lu, Haiyun; MacCormick, Marion; Markov, Nikolai; Mattione, Paul; Mazouz, Malek; McKinnon, Bryan; Mecking, Bernhard; Mestayer, Mac; Meyer, Curtis; Mibe, Tsutomu; Michel, Bernard; Mikhaylov, Konstantin; Mirazita, Marco; Miskimen, Rory; Mokeev, Viktor; Moreno, Brahim; Moriya, Kei; Morrow, Steven; Moteabbed, Maryam; Munevar Espitia, Edwin; Mutchler, Gordon; Nadel-Turonski, Pawel; Nasseripour, Rakhsha; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria-Ioana; Niczyporuk, Bogdan; Niroula, Megh; Niyazov, Rustam; Nozar, Mina; Osipenko, Mikhail; Ostrovidov, Alexander; Park, Kijun; Pasyuk, Evgueni; Paterson, Craig; Pereira, Sergio; Pierce, Joshua; Pivnyuk, Nikolay; Pocanic, Dinko; Pogorelko, Oleg; Pozdnyakov, Sergey; Price, John; Procureur, Sebastien; Prok, Yelena; Protopopescu, Dan; Raue, Brian; Ricco, Giovanni; Ripani, Marco; Ritchie, Barry; Ronchetti, Federico; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Salamanca, Julian; Salgado, Carlos; Santoro, Joseph; Sapunenko, Vladimir; Schumacher, Reinhard; Serov, Vladimir; Sharabian, Youri; Sharov, Dmitri; Shvedunov, Nikolay; Smith, Elton; Smith, Lee; Sober, Daniel; Sokhan, Daria; Stavinsky, Aleksey; Stepanyan, Samuel; Stepanyan, Stepan; Stokes, Burnham; Stoler, Paul; Strakovski, Igor; Strauch, Steffen; Taiuti, Mauro; Tedeschi, David; Tkabladze, Avtandil; Tkachenko, Svyatoslav; Tur, Clarisse; Ungaro, Maurizio; Vineyard, Michael; Vlassov, Alexander; Voutier, Eric; Watts, Daniel; Weinstein, Lawrence; Weygand, Dennis; Williams, Michael; Wolin, Elliott; Wood, Michael; Yegneswaran, Amrit; Zana, Lorenzo; Zhang, Jixie; Zhao, Zhiwen

    2008-04-01

    The beam spin asymmetry (BSA) in the exclusive reaction e-vector p-->eppi0 was measured with the CEBAF 5.77 GeV polarized electron beam and Large Acceptance Spectrometer (CLAS). The xB,Q2,t, and phi dependences of the pi0 BSA are presented in the deep inelastic regime. The asymmetries are fitted with a sinphi function and their amplitudes are extracted. Overall, they are of the order of 0.04â 0.11 and roughly independent of t. This is the signature of a nonzero longitudinal-transverse interference. The implications concerning the applicability of a formalism based on generalized parton distributions, as well as the extension of a Regge formalism at high photon virtualities, are discussed.

  16. 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

    2007-07-23

    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.

  17. New analysis concerning the strange quark polarization puzzle

    E-Print Network [OSTI]

    Elliot Leader; Alexander V. Sidorov; Dimiter B. Stamenov

    2015-07-09

    The fact that analyses of semi-inclusive deep inelastic scattering suggest that the polarized strange quark density $\\Delta s(x) + \\Delta \\bar{s}(x)$ is positive in the measured region of Bjorken x, whereas all analyses of inclusive deep inelastic scattering yield significantly negative values of this quantity, is known as the "strange quark polarization puzzle". We have analyzed the world data on inclusive deep inelastic scattering, including the COMPASS 2010 proton data on the spin asymmetries, and for the first time, the new extremely precise JLab CLAS data on the proton and deuteron spin structure functions. Despite allowing in our parametrization, for a possible sign change, our results confirm that the inclusive data yield significantly negative values for the polarized strange quark density.

  18. Measurement of the EMC effect in the deuteron

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

    Griffioen, Keith A.; Arrington, John R.; Christy, M. Eric; Ent, Rolf; Kalantarians, Narbe; Keppel, Cynthia E.; Kuhn, Sebastian E.; Melnitchouk, Wally; Niculescu, Gabriel; Niculescu, Ioana; et al

    2015-07-01

    We have determined the structure function ratio $R^d_{\\rm EMC}=F_2^d/(F_2^n+F_2^p)$ from recently published $F_2^n/F_2^d$ data taken by the BONuS experiment using CLAS at Jefferson Lab. This ratio deviates from unity, with a slope $dR_{\\rm EMC}^{d}/dx= -0.10\\pm 0.05$ in the range of Bjorken $x$ from 0.35 to 0.7, for invariant mass $W>1.4$ GeV and $Q^2>1$ GeV$^2$. The observed EMC effect for these kinematics is consistent with conventional nuclear physics models that include off-shell corrections, as well as with empirical analyses that find the EMC effect proportional to the probability of short-range nucleon-nucleon correlations.

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

    SciTech Connect (OSTI)

    Taylor, Charles E.; Cole, Philip L.

    2014-01-01

    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.

  20. phi-meson photoproduction on Hydrogen in the neutral decay mode

    SciTech Connect (OSTI)

    Seraydaryan, Helena; Amaryan, Moscov J.; Gavalian, Gagik; Baghdasaryan, Hovhannes A.; Weinstein, Larry

    2014-05-01

    We report the first measurement of the photoproduction cross section of the $\\phi$ meson in its neutral decay mode in the reaction $\\gamma p \\to p\\phi(K_SK_L)$. The experiment was performed with a tagged photon beam of energy $1.6 \\le E_\\gamma \\le 3.6$ GeV incident on a liquid hydrogen target of the CLAS spectrometer at the Thomas Jefferson National Accelerator Facility. The $p \\phi$ final state is identified via reconstruction of $K_S$ in the invariant mass of two oppositely charged pions and by requiring the missing particle in the reaction $\\gamma p \\to p K_S X$ to be $K_L$. The presented results significantly enlarge the existing data on $\\phi$-photoproduction. These data, combined with the data from the charged decay mode, will help to constrain different mechanisms of $\\phi$ photoproduction.

  1. 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.,

    2015-05-01

    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

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

    SciTech Connect (OSTI)

    Djalali, Chaden; Paolone, Michael; Weygand, Dennis; Wood, Mike H.

    2014-09-01

    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.

  3. 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

    2012-02-21

    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.

  4. 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

    2015-01-01

    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.

  5. 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

    2015-03-18

    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.

  6. Hybrid Mesons

    E-Print Network [OSTI]

    C. A. Meyer; E. S. Swanson

    2015-03-04

    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.

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

    E-Print Network [OSTI]

    Senderovich, I; Dugger, M; Ritchie, B G; Pasyuk, E; Tucker, R; Brock, J; Carlin, C; Keith, C D; Meekins, D G; Seely, M L; R, D; D, M; Collins, P; Adhikari, K P; Adikaram, D; Akbar, Z; Anderson, M D; Pereira, S Anefalos; Badui, R A; Ball, J; Baltzell, N A; Battaglieri, M; Batourine, V; Bedlinskiy, I; Biselli, A S; Boiarinov, S; Briscoe, W J; Brooks, W K; Burkert, V D; 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; Dupre, R; Egiyan, H; Alaoui, A El; Fassi, L El; Fradi, A; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Filippi, A; Fleming, J A; Garillon, B; Ghandilyan, Y; Gilfoyle, G P; Giovanetti, K L; Girod, F -X; Glazier, D I; Goetz, J T; Gohn, W; Golovatch, E; Gothe, R W; Griffioen, K A; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; 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; Joosten, S; Keller, D; Khachatryan, G; Khandaker, M; Kim, A; Klein, F J; Kubarovsky, V; Kunkel, M C; Lenisa, P; Livingston, K; Lu, H Y; MacGregor, I J D; Mattione, P; McKinnon, B; Meyer, C A; Mineeva, T; Mokeev, V; Montgomery, R A; Movsisyan, A; Camacho, C Munoz; Nadel-Turonski, P; Net, L A; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Park, K; Park, S; Peng, P; Phelps, W; Pisano, S; Pogorelko, O; Price, J W; Prok, Y; Puckett, A J R; Ripani, M; Rizzo, A; Rosner, G; Roy, P; Sabatie, F; Salgado, C; Schott, D; Schumacher, R A; Seder, E; Simonyan, A; Skorodumina, Iu; Smith, G D; Sober, D I; Sokhan, D; Sparveris, N; Stepanyan, S; Stoler, P; Strakovsky, I I; Strauch, S; Sytnik, V; Tian, Ye; Ungaro, M; Voskanyan, H; Voutier, E; Walford, N K; Wei, X; Wood, M H; Zachariou, N; Zana, L; Zhang, J; Zhao, Z W; Zonta, I

    2015-01-01

    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. Cascade spectroscopy in photoproduction on a proton target at Jefferson Lab

    SciTech Connect (OSTI)

    L. Guo; D. P. Weygand

    2005-10-01

    The CLAS Collaboration at Jefferson Lab conducted a photoproduction experiment on a proton target using a tagged photon beam with an energy range of 1.5-3.8 GeV during May-July 2004. With an integrated luminosity of about 75 pb{sup -1}, this experiment provides the largest data set for photon-proton reactions ever collected. The reaction {gamma}p {yields} K{sup +}K{sup +}{Xi}{sup -}(1320) has been investigated and the preliminary results of the cross section measurement of {Xi}{sup -}(1320) for the photon energy range of 2.7-3.8 GeV have been obtained. In a search for excited cascade states, the reaction of {gamma}p {yields} K{sup +}K{sup +}{pi}{sup -}({Xi}{sup 0}(1320)) has also been explored.

  9. 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.,

    2015-05-01

    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.

  10. 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

    2011-04-01

    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 $\\Sigma^0(1385) \\to \\Lambda\\gamma$.

  11. Electroexcitation of the P33(1232), P11(1440), D13(1520), S11(1535) at Q^2=0.4 and 0.65(GeV/c)^2

    E-Print Network [OSTI]

    I. G. Aznauryan; V. D. Burkert; H. Egiyan; K. Joo; R. Minehart; L. C. Smith

    2004-12-21

    Using two approaches: dispersion relations and isobar model, we have analyzed recent high precision CLAS data on cross sections of \\pi^0, \\pi^+, and \\eta electroproduction on protons, and the longitudinally polarized electron beam asymmetry for p(\\vec{e},e'p)\\pi^0 and p(\\vec{e},e'n)\\pi^+. The contributions of the resonances P33(1232), P11(1440), D13(1520), S11(1535) to \\pi electroproduction and S11(1535) to \\eta electroproduction are found. The results obtained in the two approaches are in good agreement with each other. There is also good agreement between amplitudes of the \\gamma^* N \\to S11(1535) transition found in \\pi and \\eta electroproduction. For the first time accurate results are obtained for the longitudinal amplitudes of the P11(1440), D13(1520) and S11(1535) electroexcitation on protons.

  12. Incoherent photoproduction of $?$-meson from deuteron at low energies

    E-Print Network [OSTI]

    Alvin Kiswandhi; YuBing Dong; Shin Nan Yang

    2014-02-14

    The LEPS and CLAS data of the incoherent photoproduction of $\\phi$ meson from deuteron at low energies are studied with a model for $\\phi$ meson photoproduction from nucleon consisting of Pomeron, $\\pi$, and $\\eta$ meson exchanges in the t-channel, and a postulated resonance, with parameters fitted to recent LEPS data on $\\phi$ production from proton near threshold. The resonance was introduced to explain an observed bump in the forward differential cross section. Within impulse approximation, we find that the Fermi motion, final state interaction, and the resonance excitation all give important contributions to improve the agreement with data. However, discrepancies remain. Contributions from $\\phi$ production via spectator nucleon by other mesons like $\\pi, \\rho,$ and $\\phi$ produced from the first nucleon need to be calculated in order to gain insight on the medium effects as well as the existence of the postulated nucleon resonance.

  13. 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

    2015-07-01

    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.

  14. Cross sections for the exclusive photon electroproduction on the proton and Generalized Parton Distributions

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

    Jo, Hyon -Suk

    2015-11-17

    Unpolarized and beam-polarized four-fold cross sections $\\frac{d^4 \\sigma}{dQ^2 dx_B dt d\\phi}$ for the $ep\\to e^\\prime p^\\prime \\gamma$ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 ($Q^2,x_B,t$) bins over the widest phase space ever explored in the valence-quark region. Several models of Generalized Parton Distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD $H$, expected to be the dominant contributor to these observables. Thus, through a leading-twist extraction of Compton Form Factors, these results reveal a tomographic imagemore »of the nucleon.« less

  15. Nucleon Resonances Near 2 GeV

    E-Print Network [OSTI]

    He, Jun

    2015-01-01

    The nucleon resonances near 2 GeV are investigated through the $\\Sigma$(1385) and $\\Lambda(1520)$ photoproductions within a Regge-plus-resonance approach based on the new experimental data released by the CLAS Collaboration. The $\\Delta(2000)$ and the $N(2120)$ are found essential to reproduce the experimental data and should be assigned as second $[\\Delta 5/2^+]$ and third $[N3/2^-]$ in the constituent quark model, respectively. A calculation of the binding energy and decay pattern supports that the $N(1875)$, which is listed in the PDG as the third $N3/2^-$ nucleon resonance instead of the $N(2120)$, is from the $\\Sigma(1385)K$ interaction rather than a three quark state.

  16. 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

    2014-01-01

    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.

  17. Isospin Decomposition of the Photoproduced Sigma pi System Near the Lambda(1405)

    SciTech Connect (OSTI)

    Carnegie Mellon U.; Indiana U.

    2013-09-01

    Recent experimental results for the reaction \\gamma + p \\to K^+ + \\Sigma + \\pi\\ from CLAS at Jefferson Lab are discussed. It was found that the mass distributions or "line shapes" of the three charge combinations \\Sigma^+ \\pi^-, \\Sigma^0 \\pi^0 and \\Sigma^- \\pi^+ differ significantly. Our results show that the \\Lambda(1405), as the I=0 constituent of the reaction, must be accompanied by an I > 0 component. We discuss phenomenological fits to the data to test the possible forms and magnitudes of these amplitudes. A two-amplitude I=0 fit of Breit-Wigner form to the \\Sigma^0\\pi^0 channel alone works quite well. The addition of a single I=1 amplitude works fairly well to model all the line shapes simultaneously.

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

    E-Print Network [OSTI]

    L. B. Weinstein; R. Niyazov

    2002-10-01

    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.

  19. Coherent Photoproduction of pi^+ from 3^He

    E-Print Network [OSTI]

    Rakhsha Nasseripour; Barry Berman; the CLAS Collaboration

    2010-10-30

    We have measured the differential cross section for the $\\gamma$$^3$He$\\rightarrow \\pi^+ t$ reaction. This reaction was studied using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid $^3$He target. The differential cross sections for the $\\gamma$$^3$He$\\rightarrow \\pi^+ 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.

  20. 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)

    2014-05-01

    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.

  1. 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.

    1995-12-31

    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.

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

    SciTech Connect (OSTI)

    Graham, Lewis P.

    2012-12-01

    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.

  3. Dual parametrization of the proton generalized parton distribution functions H and E, and description of the deeply virtual Compton scattering cross sections and asymmetries

    SciTech Connect (OSTI)

    Guzey, V.; Teckentrup, T. [Institut fuer Theoretische Physik II, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

    2006-09-01

    We develop the minimal model of a new leading order parametrization of generalized parton distributions (GPDs) introduced by Polyakov and Shuvaev. The model for GPDs H and E is formulated in terms of the forward quark distributions, the Gegenbauer moments of the D-term, and the forward limit of the GPD E. The model is designed primarily for small and medium-size values of x{sub B}, x{sub B}{<=}0.2. We examine two different models of the t dependence of the GPDs: the factorized exponential model and the nonfactorized Regge-motivated model. Using our model, we successfully described the deeply virtual Compton scattering (DVCS) cross section measured by H1 and ZEUS, the moments of the beam-spin A{sub LU}{sup sin{phi}}, the beam-charge A{sub C}{sup cos{phi}}, and the transversely polarized target A{sub UT}{sup sin{phi}}{sup cos{phi}} DVCS asymmetries measured by HERMES and A{sub LU}{sup sin{phi}} measured by CLAS. The data on A{sub C}{sup cos{phi}} prefer the Regge-motivated model of the t dependence of the GPDs. The data on A{sub UT}{sup sin{phi}}{sup cos{phi}} indicate that the u and d quarks carry only a small fraction of the proton total angular momentum.

  4. 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.

    2014-09-01

    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.

  5. 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

    2012-09-24

    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.

  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

    2014-06-16

    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. First measurement of target and double spin asymmetries for polarized e- polarized p --> e p pi0 in the nucleon resonance region above the Delta(1232)

    SciTech Connect (OSTI)

    Biselli, Angela; Burkert, Volker; Amaryan, Moscov; Amaryan, Moskov; Asryan, Gegham; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Baillie, Nathan; Ball, J.P.; Ball, Jacques; Baltzell, Nathan; Battaglieri, Marco; Bedlinskiy, Ivan; Bellis, Matthew; Benmouna, Nawal; Berman, Barry; Blaszczyk, Lukasz; Bookwalter, Craig; Boyarinov, Sergey; Bosted, Peter; Bradford, Robert; Branford, Derek; Briscoe, William; Brooks, William; Bultmann, S.; Bueltmann, Stephen; Butuceanu, Cornel; Calarco, John; Careccia, Sharon; Carman, Daniel; Casey, Liam; Chen, Shifeng; Cheng, Lu; Cole, Philip; Collins, Patrick; Coltharp, Philip; Crabb, Donald; Crede, Volker; Dale, Daniel; Dashyan, Natalya; De Masi, Rita; De Vita, Raffaella; De Sanctis, Enzo; Degtiarenko, Pavel; Deur, Alexandre; Dhamija, Seema; Dickson, Richard; Djalali, Chaden; Dodge, Gail; Doughty, David; Dugger, Michael; Dzyubak, Oleksandr; Egiyan, Hovanes; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Feuerbach, Robert; Fersch, Robert; Forest, Tony; Fradi, Ahmed; Garcon, Michel; Gavalian, Gagik; Gevorgyan, Nerses; Gilfoyle, Gerard; Giovanetti, Kevin; Girod, Francois-Xavier; Goetz, John; Gohn, Wesley; Gothe, Ralf; Graham, Lewis; Griffioen, Keith; Guidal, Michel; Guler, Nevzat; Guo, Lei; Gyurjyan, Vardan; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Hassall, Neil; Hicks, Kenneth; Hleiqawi, Ishaq; Holtrop, Maurik; Hyde, Charles; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Ito, Mark; Jenkins, David; Jo, Hyon-Suk; Johnstone, John; Joo, Kyungseon; Juengst, Henry; Kalantarians, Narbe; Keller, Dustin; Kellie, James; Khandaker, Mahbubul; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Kossov, Mikhail; Krahn, Zebulun; Kubarovsky, Valery; Kuhn, Joachim; Kuhn, Sebastian; Kuleshov, Sergey; Kuznetsov, Viacheslav; Lachniet, Jeff; Laget, Jean; Langheinrich, Jorn; Lawrence, David; Livingston, Kenneth; Lu, Haiyun; MacCormick, Marion; Markov, Nikolai; Mattione, Paul; McKinnon, Bryan; McNabb, John; Mecking, Bernhard; Mestayer, Mac; Meyer, Curtis; Mibe, Tsutomu; Mikhaylov, Konstantin; Mirazita, Marco; Mokeev, Viktor; Moreno, Brahim; Moriya, Kei; Morrow, Steven; Moteabbed, Maryam; Munevar Espitia, Edwin; Mutchler, Gordon; Nadel-Turonski, Pawel; Nasseripour, Rakhsha; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria-Ioana; Niczyporuk, Bogdan; Niroula, Megh; Niyazov, Rustam; Nozar, Mina; Osipenko, Mikhail; Ostrovidov, Alexander; Park, Kil; Park, Seungkyung; Pasyuk, Evgueni; Paterson, Craig; Pereira, Sergio; Pierce, Joshua; Pivnyuk, Nikolay; Pogorelko, Oleg; Pozdnyakov, Sergey; Price, John; Prok, Yelena; Protopopescu, Dan; Raue, Brian; Ricco, Giovanni; Ripani, Marco; Ritchie, Barry; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Saini, Mukesh; Salamanca, Julian; Salgado, Carlos; Santoro, Joseph; Sapunenko, Vladimir; Schott, Diane; Schumacher, Reinhard; Serov, Vladimir; Sharabian, Youri; Sharov, Dmitri; Shvedunov, Nikolay; Smith, Elton; Sober, Daniel; Sokhan, Daria; Stavinskiy, Aleksey; Stepanyan, Samuel; Stepanyan, Stepan; Stokes, Burnham; Stoler, Paul; Strakovski, Igor; Strauch, Steffen; Taiuti, Mauro; Tedeschi, David; Tkabladze, Avtandil; Tkachenko, Svyatoslav; Todor, Luminita; Ungaro, Maurizio; Vineyard, Michael; Vlassov, Alexander; Watts, Daniel; Weinstein, Lawrence; Weygand, Dennis; Williams, M.; Wolin, Elliott; Wood, Michael; Yegneswaran, Amrit; Yurov, Mikhail; Zana, Lorenzo; Zhang, Jixie; Zhao, Bo; Zhao, Zhiwen

    2008-10-01

    DOI: http://dx.doi.org/10.1103/PhysRevC.78.045204
    The exclusive channel polarized proton(polarized e,e prime p)pi0 was studied in the first and second nucleon resonance regions in the Q2 range from 0.187 to 0.770 GeV2 at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). Longitudinal target and beam-target asymmetries were extracted over a large range of center-of-mass angles of the pi0 and compared to the unitary isobar model MAID, the dynamic model by Sato and Lee, and the dynamic model DMT. A strong sensitivity to individual models was observed, in particular for the target asymmetry and in the higher invariant mass region. This data set, once included in the global fits of the above models, is expected to place strong constraints on the electrocoupling amplitudes A_{1/2} and S_{1/2} for the Roper resonance N(1400)P11, and the N(1535)S11 and N(1520)D13 states.

  8. 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

    2014-11-25

    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$^2$.

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

    E-Print Network [OSTI]

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

    2006-11-21

    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.

  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.

    2005-09-29

    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. Photoproduction of K*+ Lambda and K+Sigma(1385) in the reaction gamma p-->K+Lambda pi0 at Jefferson Lab

    SciTech Connect (OSTI)

    L. Guo; D. P. Weygand

    2005-10-01

    The search for missing nucleon resonances using coupled channel analysis has mostly been concentrated on N{pi} and KY channels, while the contributions of K*Y and KY* channels have not been investigated thoroughly mostly due to the lack of data. With an integrated luminosity of about 75 pb{sup -1}, the photoproduction data using a proton target recently collected by the CLAS Collaboration at Jefferson Lab with a photon energy range of 1.5-3.8 GeV provided large statistics for the study of light hyperon photoproduction through exclusive reactions. The reaction {gamma}p {yields} K{sup +}{Lambda}{pi}{sup 0} has been investigated. Preliminary results of the K*{sup +} {Lambda} and K{sup +}{Sigma}(1385) cross sections are not negligible compared with the KY channels. The {Lambda}{pi}{sup 0} invariant mass spectrum is dominated by the {Sigma}(1385) signal and no significant structure was found around the {Sigma}(1480) region.

  12. Exclusive processes at JLab at 6 GeV

    SciTech Connect (OSTI)

    Kim, Andrey

    2015-01-01

    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.

  13. 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

    2015-02-10

    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

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

    SciTech Connect (OSTI)

    Gohn, Wesley P.; Avakian, Harut A.; Joo, Kyungseon; Ungaro, Maurizio

    2014-04-01

    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.

  15. 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

    2013-07-10

    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 $0.830\\leq \\epsilon\\leq 0.943$.

  16. Electron Scattering From High-Momentum Neutrons in Deuterium

    E-Print Network [OSTI]

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

    2005-10-12

    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.

  17. 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

    2006-06-27

    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.

  18. Electron Scattering From High-Momentum Neutrons in Deuterium

    SciTech Connect (OSTI)

    A.V. Klimenko; S.E. Kuhn

    2005-10-12

    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.

  19. Search for the Theta+ pentaquark in the reactions gammap-->[overline K]0K+n and gammap-->[overline K]0K0p

    SciTech Connect (OSTI)

    Raffaella De Vita; Marco Battaglieri; V. Kubarovsky; Nathan Baltzell; Matthew Bellis; John Goett; Lei Guo; Gordon Mutchler; Paul Stoler; Maurizio Ungaro; Dennis Weygand; Moscov Amaryan; Pawel Ambrozewicz; Marco Anghinolfi; Gegham Asryan; Harutyun AVAKIAN; Harutyun Avakian; Hovhannes Baghdasaryan; Nathan Baillie; Jacques Ball; Vitaly Baturin; Ivan Bedlinski; Ivan Bedlinskiy; Nawal Benmouna; Barry Berman; Angela Biselli; Sergey Boyarinov; Sylvain Bouchigny; Robert Bradford; Derek Branford; William Briscoe; William Brooks; Stephen Bueltmann; Volker Burkert; Cornel Butuceanu; John Calarco; Sharon Careccia; Daniel Carman; Shifeng Chen; Eric Clinton; Philip Cole; Patrick Collins; Philip Coltharp; Donald Crabb; Hall Crannell; Volker Crede; John Cummings; D. Dale; Raffaella De Vita; Enzo De Sanctis; Pavel Degtiarenko; Alexandre Deur; Kahanawita Dharmawardane; Chaden Djalali; Gail Dodge; Joseph Donnelly; David Doughty; Michael Dugger; Oleksandr Dzyubak; Hovanes Egiyan; Kim Egiyan; Lamiaa Elfassi; Latifa Elouadrhiri; Paul Eugenio; Gleb Fedotov; Herbert Funsten; Marianna Gabrielyan; Liping Gan; Michel Garcon; Ashot Gasparian; Gagik Gavalian; Gerard Gilfoyle; Kevin Giovanetti; Francois-Xavier Girod; Oleksandr Glamazdin; John Goetz; Evgueni Golovatch; Atilla Gonenc; Christopher Gordon; Ralf Gothe; Keith Griffioen; Michel Guidal; Nevzat Guler; Harutyun Gyurjyan; Cynthia Hadjidakis; Kawtar Hafidi; Hayk Hakobyan; Rafael Hakobyan; John Hardie; F. Hersman; Kenneth Hicks; Ishaq Hleiqawi; Maurik Holtrop; Charles Hyde-Wright; Yordanka Ilieva; David Ireland; Boris Ishkhanov; Eugeny Isupov; Mark Ito; D. Jenkins; Hyon-Suk Jo; Kyungseon Joo; Henry Juengst; James Kellie; Mahbubul Khandaker; Wooyoung Kim; Andreas Klein; Franz Klein; Alexei Klimenko; Mikhail Kossov; Laird Kramer; Joachim Kuhn; Sebastian Kuhn; Sergey Kuleshov; Jeff Lachniet; Jean Laget; Jorn Langheinrich; Dave Lawrence; Tsung-shung Lee; Ji Li; K. Livingston; Haiyun Lu; Marion MacCormick; Nikolai Markov; Bryan McKinnon; Bernhard Mecking; Joseph Melone; Mac Mestayer; Curtis Meyer; Tsutomu Mibe; Konstantin Mikhaylov; Ralph Minehart; Marco Mirazita; R. Miskimen; Vasiliy Mochalov; Viktor Mokeev; Ludyvine Morand; Steven Morrow; Maryam Moteabbed; Pawel Nadel-Turonski; Itaru Nakagawa; Rakhsha Nasseripour; Silvia Niccolai; Gabriel Niculescu; Maria-Ioana Niculescu; Bogdan Niczyporuk; Megh Niroula; Rustam Niyazov; Mina Nozar; Mikhail Osipenko; Alexander Ostrovidov; Kijun Park; Evgueni Pasyuk; Craig Paterson; Joshua Pierce; Nikolay Pivnyuk; Dinko Pocanic; Oleg Pogorelko; Sergey Pozdnyakov; John Price; Yelena Prok; Dan Protopopescu; Brian Raue; Gregory Riccardi; Giovanni Ricco; Marco Ripani; Barry Ritchie; Federico Ronchetti; Guenther Rosner; Patrizia Rossi; Franck Sabatie; Carlos Salgado; Joseph Santoro; Vladimir Sapunenko; Reinhard Schumacher; Vladimir Serov; Youri Sharabian; Nikolay Shvedunov; Elton Smith; Lee Smith; Daniel Sober; Aleksey Stavinskiy; Samuel Stepanyan; Stepan Stepanyan; Burnham Stokes; Igor Strakovski; Steffen Strauch; Mauro Taiuti; David Tedeschi; Aram Teymurazyan; Ulrike Thoma; Avtandil Tkabladze; Svyatoslav Tkachenko; Luminita Todor; Clarisse Tur; Michael Vineyard; Alexander Vlassov; Daniel Watts; Lawrence Weinstein; M. Williams; Elliott Wolin; Michael Wood; Amrit Yegneswaran; Lorenzo Zana; Jixie Zhang; Bo Zhao; Zhiwen Zhao

    2006-11-16

    The exclusive reactions {gamma}p {yields} {bar K}{sup 0} K{sup +} n and {gamma}p {yields} {bar K}{sup 0} K{sup 0} p have been studied in the photon energy range 1.6--3.8 GeV, searching for evidence of the exotic baryon {Theta}{sup +}(1540) in the decays {Theta}{sup +} {yields} nK{sup +} and {Theta}{sup +} {yields} pK{sup 0}. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The integrated luminosity was about 70 pb{sup -1}. The reactions have been isolated by detecting the K{sup +} and proton directly, the neutral kaon via its decay to K{sub S} {yields} {pi}{sup +}{pi}{sup -} and the neutron or neutral kaon via the missing mass technique. The mass and width of known hyperons such as {Sigma}{sup +}, {Sigma}{sup -} 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}{sup 0} K{sup +} n and {bar K}{sup 0} K{sup 0} p final state respectively. No evidence for the {Theta}{sup +} pentaquark was found in the nK{sup +} or pK{sub S} invariant mass spectra. Upper limits were set on the production cross section of the reaction {gamma}p {yields} {Theta}{sup +} {bar K}{sup 0} as functions of center-of-mass angle, nK{sup +} and pK{sub 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}{sup +} width, {Gamma}{sub {Theta}{sup +}}, ranging between 0.01 and 7 MeV.

  20. 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

    2013-08-01

    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.

  1. Electromagnetic calorimeter for the Heavy Photon Search Experiment at Jefferson Lab

    SciTech Connect (OSTI)

    Buchanan, Emma

    2014-11-01

    The Heavy Photon Search Experiment (HPS) seeks to detect a hypothesised hidden sector boson, the A', predicted to be produced in dark matter decay or annihilation. Theories suggest that the A' couples weakly to electric charge through kinetic mixing, allowing it, as a result, to decay to Standard Matter (SM) lepton pair, which may explain the electron and positron excess recently observed in cosmic rays. Measuring the lepton pair decay of the A' could lead to indirect detection of dark matter. The HPS experiment is a fixed target experiment that will utilize the electron beam produced at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). The detector set-up includes a silicon vertex tracker (SVT) and an Electromagnetic Calorimeter (ECal). The ECal will provide the trigger and detect e+e- pairs and its construction and testing forms the focus of this thesis. The ECal consists of 442 PbWO4} tapered crystals with a length 16cm and a 1.6x1.6cm^2 cross-section, stacked into a rectangular array and are coupled to Large Area APDs and corresponding pre-amplifiers. Supplementary to the ECal is a Light Monitoring System (LMS) consisting of bi-coloured LEDs that will monitor changes in APD gain and crystal transparency due to radiation damage. Before construction of the ECal each of the components were required to be individually tested to determine a number of different characteristics. Irradiation tests were performed on PbWO4 ECal crystals and, as a comparison, one grown by a different manufacturer to determine their radiation hardness. A technique for annealing the radiation damage by optical bleaching, which involves injecting light of various wavelengths into the crystal, was tested using the blue LED from the LMS as a potential candidate. The light yield dependence on temperature was also measured for one of the PbWO4 crystal types. Each APD was individually tested to determine if they functioned correctly and within the requirements of the experiment, then arranged into groups of similar gain at chosen applied voltages, for connection to High Voltage (HV) supplies. Each bi-coloured LED was also tested to determine if they functioned within the specifications of the experiment; including their signal quality at high frequency and their radiation hardness. The HPS crystals were recycled from a previous Jefferson Lab detector, the Inner Calorimeter from CLAS, which needed to be dismantled and reconditioned using various removal and cleaning techniques. The HPS ECal was then constructed in a new formation using a combination of different gluing and construction techniques, and initial functionality tests were performed.

  2. 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 A.; Weinstein, Lawrence B.

    2013-08-30

    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

  3. 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

    2013-08-01

    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.