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1

Meson Spectroscopy at CLAS and CLAS12  

Science Conference Proceedings (OSTI)

We report on meson spectroscopy using the CLAS at Jefferson Lab. We study photo?production of exotic mesons and strangeonia on the largest data sample ever to be produced at photon energies of about 5 GeV. We also describe an experiment to continue meson spectroscopy at CLAS12 (CLAS energy upgrade) using electroproduction at very low Q 2 (“quasireal photons”) up to photon energies of 10 GeV.

Carlos Salgado; The CLAS Collaboration

2011-01-01T23:59:59.000Z

2

Hyperon Production with CLAS and CLAS12  

Science Conference Proceedings (OSTI)

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

Eugene Pasyuk

2012-12-01T23:59:59.000Z

3

Spin physics with CLAS and CLAS12  

Science Conference Proceedings (OSTI)

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

Angela Biselli

2011-10-01T23:59:59.000Z

4

Pentaquark Searches With CLAS  

DOE Green Energy (OSTI)

The production of a possible, exotic S=1 pentaquarks off protons and neutrons is being investigated in Hall B at Jefferson Lab. Three dedicated experiments have been carried out to search for pentaquark signals using the CLAS detector in conjunction with a photon beam incident on hydrogen and deuterium targets. The status of on-going analyses and preliminary results from a variety of channels are presented.

David J. Tedeschi

2006-02-01T23:59:59.000Z

5

Hadron Spectroscopy at CLAS  

DOE Green Energy (OSTI)

Meson photoproduction was studied at the CEBAF Large Acceptance Spectrometer (CLAS) utilizing a 5.5 GeV/c photon beam incident on a hydrogen target. Here we report on the partial wave analyzes (PWA) performed on the exclusive final states pi{sup +}pi{sup +}pi{sup -}n and K{sup +}K{sup -}pi{sup +}n. In addition, CLAS has data on the final state pi{sup +}pi{sup 0}pi{sup -}p which will be reported in the near future. The analysis of the pi{sup +}pi{sup +}pi{sup -} system shows clearly the a2(1320), as well as evidence for the a1(1260) and the pi2(1670). The pi1(1600), previously observed in {pi}{sup -}p interactions, is seen very weakly here. In the K{sup +}K{sup -}pi{sup +}n channel there is evidence for the Theta{sup +}(1540) S=+1 baryon pentaquark. The PWA of this system gives an excellent description of the background which rules out mesonic reflection as a source of the signal.

Dennis Weygand

2005-05-01T23:59:59.000Z

6

Hadron Physics with CLAS12  

DOE Green Energy (OSTI)

Hadron spectroscopy has been an essential part of the physics program with the CLAS detector in experimental Hall B at Jefferson Lab. Production of baryon and meson resonances with high energy (polarized) electron and photon beams was studied on a veriety of targets, ranging from hydrogen to lead. Physics topics of interest include: investigation of the spectrum of baryon and meson resonances, transition form-factors, meson-nucleon couplings (mesons in nuclei), and search for exotic and missing states. With the 12 GeV upgrade of the CEBAF machine, hadron spectroscopy in Hall B will be extended to a new domain of higher mass resonances and the range of higher transferred momentum using up to 11 GeV electron beams and the upgraded CLAS12 detector. In this paper a brief description of the CLAS12 detector and the physics program adopted for 12 GeV with emphasis to baryon and meson spectroscopy is presented.

Stepan Stepanyan

2010-08-01T23:59:59.000Z

7

Deeply virtual Compton scattering with CLAS and CLAS12  

SciTech Connect

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.

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

2012-06-01T23:59:59.000Z

8

Single spin asymmetries at CLAS  

DOE Green Energy (OSTI)

We present recent results from Jefferson Lab's CLAS detector on beam and target single-spin asymmetries in single pion electroproduction off unpolarized hydrogen and polarized NH 3 targets. Non-zero single-beam and single-target spin asymmetries are observed for the first time in semi-inclusive and exclusive pion production in hard-scattering kinematics.

Harut Avakian; Latifa Elouadrhiri

2003-05-19T23:59:59.000Z

9

Meson Photoproduction Experiments with CLAS  

SciTech Connect

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

Eugene Pasyuk

2012-12-01T23:59:59.000Z

10

An Overview of Recent Results from CLAS  

SciTech Connect

The unique capabilities of the CLAS detector to measure exclusive meson electroproduction off protons, with almost complete coverage of the final hadron phase space, has extended our knowledge of excited baryon structure. Consistent results from Np and Npp final states provide convincing evidence for reliable extraction of N* electrocouplings. Theoretical analyses of these results, using self-consistent dynamical calculations using an internal quark core and an external meson-baryon cloud suggest that meson-baryon dressing amplitudes need to be included. The meson-baryon dressing was already shown to be necessary to get agreement between calculations and data on the D resonance transition magnetic moment at low Q{sup 2}. Similarly, a new measurement of the transition magnetic moment for strange baryons also disagrees with quark models, suggesting the need for meson-baryon dressings. In the near future, the CLAS detector will be replaced with CLAS12, providing new high-precision data.

Kenneth Hicks

2011-12-01T23:59:59.000Z

11

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

Open Energy Info (EERE)

En.lighten Country Lighting Assessments (CLAs) En.lighten Country Lighting Assessments (CLAs) Jump to: navigation, search Tool Summary LAUNCH TOOL Name: En.lighten Country Lighting Assessments (CLAs) Agency/Company /Organization: United Nations Environment Programme Sector: Energy Focus Area: Energy Efficiency, Buildings Topics: Resource assessment Website: hqweb.enlighten-initiative.org/CountrySupport/CountryLightingAssessmen En.lighten Country Lighting Assessments (CLAs) Screenshot References: CLAs[1] Logo: En.lighten Country Lighting Assessments (CLAs) About "A large scale shift to efficient lighting is one of the most effective and economically advantageous means to combat climate change. In order to demonstrate the potential opportunities in terms of CO2 emissions reduction and financial economies to be realized by countries that adopt efficient

12

A position sensitive photon detector for the CLAS12 ring imaging ?erenkov application.  

E-Print Network (OSTI)

??The upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) to CLAS12 will offer unique possibilities to study the strong interaction… (more)

Montgomery, Rachel Ann

2013-01-01T23:59:59.000Z

13

Search for New and Unusual Stangonia using CLAS  

SciTech Connect

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.

Saini, Mukesh Satyapraka [Florida State U.

2013-03-01T23:59:59.000Z

14

Hadron Spectroscopy Program with CLAS g12  

SciTech Connect

Some conclusions from this presentation are: (1) previous CLAS result on exotic {pi}{sub 1}(1600)/{alpha}{sub 2}(1320) in photoproduction confirmed with higher statistics; (2) previous CLAS result on {gamma}p {yields} pentaquark not confirmed with higher statistics; (3) high luminosity allows exploitation of rare topologies {gamma}p {yields} {phi}{pi}{sup 0}p, {phi}{eta}p, {phi}{omega}p; (4) no observation of any {Xi}* states above 1530 MeV recoiling off of K{sup +}K{sup +} lepton detection permits high statistic study of pseudoscalar dalitz decay; and (5) first observation of {eta}' Dalitz decay, {rho}-{omega} interference via e{sup +}e{sup -} channel.

Dennis Weygand

2011-12-01T23:59:59.000Z

15

Meson Production and Baryon Resonances at CLAS  

Science Conference Proceedings (OSTI)

I give a brief overview of the exploration of baryon properties in meson photo- and electroproduction. These processes provide ample information for the study of electromagnetic couplings of baryon resonances and to search for states, yet to be discovered. The CLAS detector, combined with the use of energy-tagged polarized photons and polarized electrons, as well as polarized targets and the measurement of recoil polarization, provide the tools for a comprehensive nucleon resonance program. I briefly present the status of this program, prospects for the next few years, and plans for the Jefferson Lab 12 GeV upgrade.

Volker Burkert

2011-02-01T23:59:59.000Z

16

Meson Production and Baryon Resonances at CLAS  

E-Print Network (OSTI)

I give a brief overview of the exploration of baryon properties in meson photo- and electroproduction. These processes provide ample information for the study of electromagnetic couplings of baryon resonances and to search for states, yet to be discovered. The CLAS detector, combined with the use of energy-tagged polarized photons and polarized electrons, as well as polarized targets and the measurement of recoil polarization, provide the tools for a comprehensive nucleon resonance program. I briefly present the status of this program, prospects for the next few years, and plans for the Jefferson Lab 12 GeV upgrade.

Volker D. Burkert

2010-08-17T23:59:59.000Z

17

Strangeness electroproduction on the nucleon at CLAS  

Science Conference Proceedings (OSTI)

High-precision measurements of strange particle production from both proton and neutron targets are a core part of the physics program with the CLAS spectrometer in Hall B at Jefferson Laboratory. Measurements have been carried out at beam energies up to 6 GeV in experiments with polarized beams and polarized targets. This talk will focus on the electroproduction measurements that have been completed, which include cross sections and hyperon polarization observables for K{sup +}Y (Y = {Lambda}{Sigma}{sup 0}) final states over a broad kinematic range in momentum transfer Q{sup 2} and invariant energy W, while spanning nearly the full kaon center-of-mass angular range. These data in the strangeness sector are necessary to better understand the different production mechanisms for {Lambda} and {Sigma} hyperons and to disentangle the different resonant and non-resonant amplitudes in the intermediate state. The usefulness of the CLAS electroproduction data as part of a coupled-channel model fit will be discussed as well as an outlook of this program for the future.

Daniel Carman

2012-04-01T23:59:59.000Z

18

UNIVERSITY OF CALIFORNIA- BERKELEY UCRL CLAS CO  

NLE Websites -- All DOE Office Websites (Extended Search)

> D > H 0 z r > DO 0 1} ^ 0 :D - > D > H 0 z r > DO 0 1} ^ 0 :D - < UNIVERSITY OF CALIFORNIA- BERKELEY ^ UCRL CLAS CO ', m ^ C» 0? DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement,

19

The CLAS Excited Baryon Program at Jlab  

DOE Green Energy (OSTI)

Nucleons are complex systems of confined quarks and exhibit characteristic spectra of excited states. Highly excited nucleon states are sensitive to details of quark confinement which is poorly understood within Quantum Chromodynamics (QCD), the fundamental theory of strong interactions. Thus, measurements of excited states and the corresponding determination of their properties are needed to come to a better understanding of how confinement works in nucleons. However, the excited states of the nucleon cannot simply be inferred from cleanly separated spectral lines. Quite the contrary, a spectral analysis in nucleon resonance physics is challenging because of the fact that the resonances are broadly overlapping states which decay into a multitude of final states involving mesons and baryons. To provide a consistent and complete picture of an individual nucleon resonance, the various possible production and decay channels must be treated in a multichannel framework that permits separating resonance from background contributions. Very often, resonances reveal themselves more clearly through interference with dominant amplitudes. These interference terms can be isolated via polarization observables. The current CLAS effort is to utilize highly-polarized hydrogen and deuterium targets as well as polarized photon beams toward a complete measurement of a large number of reaction channels.

Volker Crede

2007-10-01T23:59:59.000Z

20

Overview of the recent results from CLAS  

Science Conference Proceedings (OSTI)

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

Marco Mirazita

2012-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "type-of-sale clas sification" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Photoproduction of the phi (1020) near threshold in CLAS  

DOE Green Energy (OSTI)

and kinematical coverage. Complete measurements of phi meson production on the proton have been performed at the Thomas Jefferson National Accelerator Facility using a liquid hydrogen target and the CEBAF Large Acceptance Spectrometer (CLAS). The phi was identified by missing mass using a proton and positive kaon detected by CLAS in coincidence with an electron in the photon tagger. The energy of the tagged, bremsstrahlung photons ranged from phi-threshold to 2.4 GeV. A description of the data set and the differential cross section far (E_{gamma} = 2.0 GeV ) will be presented and compared with present theoretical calculations.

D.J. Tedeschi

2002-06-01T23:59:59.000Z

22

K^*0 Photoproduction off the proton at CLAS  

DOE Green Energy (OSTI)

We report here differential cross sections for the reaction {gamma}p {yields} K*{sup 0}{Sigma}{sup +} 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.

I. Hleiqawi; K. Hicks

2005-10-01T23:59:59.000Z

23

Light Baryon Spectroscopy using the CLAS Spectrometer at Jefferson Laboratory  

Science Conference Proceedings (OSTI)

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

Volker Crede

2011-12-01T23:59:59.000Z

24

A Bayesian analysis of pentaquark signals from CLAS data  

E-Print Network (OSTI)

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.

The CLAS Collaboration; D. G. Ireland

2007-09-20T23:59:59.000Z

25

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

Science Conference Proceedings (OSTI)

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

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

2011-12-01T23:59:59.000Z

26

Properties of the Lambda(1405) Measured at CLAS  

SciTech Connect

The nature of the {Lambda}(1405), and its place in the baryon spectrum has remained uncertain for decades. Theoretical studies have shown that it may possess strong dynamical components which are not seen in other well-known baryons. Using the CLAS detector system in Hall B at Jefferson Lab, we have measured the photoproduction reaction {gamma} + p {yields} K{sup +} {Lambda}(1405) with high statistics and over different {Sigma}{pi} decay channels. The reconstructed invariant mass distribution (lineshape) has been measured, as well as the differential cross sections for the {Lambda}(1405), {Sigma}(1385), and {Lambda}(1520). Our analysis method is discussed and our near-final results for the {Lambda}(1405) lineshape and differential cross section are presented.

Kei Moriya, Reinhard Schumacher

2012-04-01T23:59:59.000Z

27

eA Pion Production at CLAS Aimed at Neutrinos  

Science Conference Proceedings (OSTI)

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.

Steven Manly

2011-11-01T23:59:59.000Z

28

Hall B superconducting magnets for the CLAS12 detector at JLAB  

Science Conference Proceedings (OSTI)

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

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

2011-02-01T23:59:59.000Z

29

GEANT SIMULATIONS OF PRESHOWER CALORIMETER FOR CLAS12 UPGRADE OF THE FORWARD ELECTROMAGNETIC CALORIMETER  

SciTech Connect

Hall B at the Thomas Jefferson National Accelerator Facility uses the CEBAF (Continuous Electron Beam Accelerator Facility) Large Acceptance Spectrometer (CLAS) to study the structure of the nucleon. An upgrade from a 6 GeV beam to a 12GeV beam is currently planned. With the beam energy upgrade, more high-energy pions will be created from the interaction of the beam and the target. Above 6GeV, the angle between the two-decay photons of high-energy pions becomes too small for the current electromagnetic calorimeter (EC) of CLAS to differentiate between two photon clusters and single photon events. Thus, a preshower calorimeter will be added in front of the EC to enable fi ner granularity and ensure better cluster separation for all CLAS experiments at higher energies. In order to optimize cost without compromising the calorimeter’s performance, three versions of the preshower, varying in number of scintillator and lead layers, were compared by their resolution and effi ciency. Using GSIM, a GEANT detector simulation program for CLAS, the passage of neutral pions and single photons through CLAS and the new preshower calorimeter (CLAS12 EC) was studied. The resolution of the CLAS12 EC was calculated from the Gaussian fi t of the sampling fraction, the energy CLAS12 EC detected over the Monte Carlo simulated energy. The single photon detection effi ciency was determined from the energy and position of the photon hits. The fractional energy resolution measured was ?E/E = 0.0972 in the fi ve-module version, 0.111 in the four-module version, and 0.149 in the three-module version. Both the fi ve- and four-module versions had 99% single photon detection effi ciency above 0.5GeV while the 3 module version had 99% effi ciency above 1.5GeV. Based on these results, the suggested preshower confi guration is the four-module version containing twelve layers of scintillator and fi fteen layers of lead. This version provides a reasonable balance of resolution, effi ciency, and cost. Additional GSIM simulations will be undertaken to verify that the four-module version has acceptable ?° mass reconstruction and to continue Research and Development (R&D) analysis on the preshower calorimeter.

Whitlow, K.; Stepanyan, S.

2007-01-01T23:59:59.000Z

30

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

SciTech Connect

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.

K.A. Griffioen

2012-12-01T23:59:59.000Z

31

Generalized parton distributions and Deeply Virtual Compton Scattering on proton at CLAS  

DOE Green Energy (OSTI)

Two measurements of target and beam spin asymmetries for the reaction ep?ep? were performed with CLAS at Jefferson Laboratory. Polarized 5.7 GeV electrons were impinging on a longitudinally polarized ammonia and liquid hydrogen target respectively. These measurements are sensitive to Generalized Parton Distributions. Sizable sin phi azimuthal angular dependences were observed in both experiments, indicating the dominance of leading twist terms and the possibility of extracting combinations of Generalized Parton Distributions on the nucleon.

R. De Masi

2007-12-01T23:59:59.000Z

32

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

E-Print Network (OSTI)

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.

W. K. Brooks

2003-11-04T23:59:59.000Z

33

Exotic Mesons at JLab Before 2013? The Search for New Forms of Matter at CLAS  

SciTech Connect

A proposal to search for exotic mesons in photoproduction has been accepted for running at Thomas Jefferson National Accelerator Facility, using the CEBAF Large Acceptance Spectrometer in Hall B. This program will bolster previously-thin statistics in many photoproduction channels, primarily those with charged particles in the final state, as well as seeking to confirm earlier findings in neutral channels, if possible. The promise of the neutral 3pi channel is discussed. In addition, the experiment seeks to study the spectrum of both exotic and ordinary strangeonia. Limitations of the CLAS detector for meson spectroscopy are discussed, as well as possible solutions to minimize such limitations.

Craig Bookwalter

2007-10-01T23:59:59.000Z

34

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

Science Conference Proceedings (OSTI)

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

Mher Aghasyan

2011-12-01T23:59:59.000Z

35

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

Science Conference Proceedings (OSTI)

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

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

2011-12-14T23:59:59.000Z

36

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

Science Conference Proceedings (OSTI)

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

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

2010-08-01T23:59:59.000Z

37

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

Science Conference Proceedings (OSTI)

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

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

2013-01-01T23:59:59.000Z

38

The Need for Polarization for Extracting Baryon Resonances and the NSTAR Program at CLAS  

SciTech Connect

We report on the NSTAR program in Hall B of JLab on using polarization observables to extract parameters of baryon resonances. The scientific purpose of the program is to improve the understanding of the underlying quark degrees of freedom, especially in the higher resonance regions, where we expect to uncover many of missing baryon resonances that mainly decay through multi-meson channels. With the high-quality beam of circularly- and linearly-polarized photons onto unpolarized and polarized proton and deteurium targets, and coupled with the nearly complete solid angle coverage of CLAS, we will extract the differential cross sections and associated polarization observables obtained by the photoproduction of vector mesons and kaons at center of mass energies of 1.7 to 2.2 GeV. The paper will primarily present the photon beam aspects of the excited baryon program.

Cole, Philip L. [Idaho State University, Dept. of Physics, Pocatello, Idaho 83209 (United States)

2007-10-26T23:59:59.000Z

39

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

Science Conference Proceedings (OSTI)

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

Rakhsha Nasseripour, Barry Berman

2011-09-01T23:59:59.000Z

40

Exclusive {rho}{sup 0} meson electroproduction from hydrogen at CLAS  

DOE Green Energy (OSTI)

The longitudinal and transverse components of the cross section for the ep {yields} e{prime}pp{sup 0} reaction were measured in Hall B at Jefferson Laboratory using the CLAS detector. The data were taken with a 4.247 GeV electron beam and were analyzed in a range of x{sub B} from 0.2 to 0.6 and of Q{sup 2} from 1.5 to 3.0 GeV{sup 2}. The data are compared to a Regge model based on effective hadronic degrees of freedom and to a calculation based on Generalized Parton Distributions. It is found that the transverse part of the cross section is well described by the former approach while the longitudinal part can be reproduced by the latter.

Cynthia Hadjidakis; Michel Guidal; Michel Garcon; Jean Laget; Elton Smith; Marc Vanderhaeghen

2004-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "type-of-sale clas sification" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Dynamic magnetic shield for the CLAS12 central TOF detector photomultiplier tubes  

SciTech Connect

The Central Time-of-Flight detector for the Jefferson Laboratory 12-GeV upgrade is being designed with linear-focused photomultiplier tubes that require a robust magnetic shield against the CLAS12 main 5-T solenoid fringe fields of 100 mT (1 kG). Theoretical consideration of a ferromagnetic cylinder in an axial field has demonstrated that its shielding capability decreases with increasing length. This observation has been confirmed with finite element analysis using Poisson model software. Several shields composed of coaxial ferromagnetic cylinders have been studied. All difficulties caused by saturation effects were overcome with a novel dynamical shield, which utilizes a demagnetizing solenoid between the shielding cylinders. Basic dynamical shields for ordinary linear-focused 2-in. photomultiplier tubes were designed and tested both with models and experimental prototypes at different external field and demagnetizing current values. Our shield design reduces the 1 kG external axial field by a factor of 5000.

V. Baturin, V. Burkert, D.S. Carman, L. Elouadrhyri, D. Grilli, D. Kashy, E. Pasyuk, L. Quettier, B. Wieland

2012-02-01T23:59:59.000Z

42

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

Science Conference Proceedings (OSTI)

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

Robert Paul Bennett

2012-04-01T23:59:59.000Z

43

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

E-Print Network (OSTI)

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.

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

2013-02-02T23:59:59.000Z

44

The Search for Exotic Mesons in gammap-->pi+pi+pi?n with CLAS at Jefferson Lab  

DOE Green Energy (OSTI)

In addition to ordinary qq-bar pairs, quantum chromodynamics (QCD) permits many other possibilities in meson spectra, such as gluonic hybrids, glueballs, and tetraquarks. Experimental discovery and study of these exotic states provides insight on the nonperturbative regime of QCD. Over the past twenty years, some searches for exotic mesons have met with controversial results, especially those obtained in the three-pion system. Prior theoretical work indicates that in photoproduction one should find gluonic hybrids at significantly enhanced levels compared to that found in pion production. To that end, the CLAS g12 run was recently completed at Jefferson Lab, using a liquid hydrogen target and tagged photons from a 5.71 GeV electron beam. The CLAS experimental apparatus was modified to maximize forward acceptance for peripheral production of mesons. The resulting data contains the world's largest 3pi photoproduction dataset, with gammap-->pi+pi+pi?n events numbering in the millions. Early results describing the data quality, kinematics, and dysnamics will be shown.

Craig Bookwalter

2010-08-01T23:59:59.000Z

45

Exclusive Electroproduction of meson rho on the nucleon Virtualite Intermediate With the CLAS Detector at Jlab; Electroproduction Exclusive de meson rho sur le nucleon Virtualite Intermediaire Avec le Detecteur CLAS at Jlab  

DOE Green Energy (OSTI)

This report presents the exclusive rho0 meson electroproduction on the nucleon at intermediate square momentum transfers Q{sup 2} (1.5 < Q{sup 2} < 3 GeV{sup 2}) and above the resonance region. The experiment has been taken place at the Jefferson laboratory with the CLAS detector, with a 4.2 GeV beam energy on a hydrogen target in the February-March 1999 period. They present the results and in particular the L/T separated cross sections. This experimentally unexplored domain experimentally is at the intersection between traditional ''soft'' hadronic physics models (VDM and Regge inspired models) and ''hard'' pQCD inspired approaches (recently introduced Generalized Parton Distribution). They discuss both approaches and their domain of validity.

Cynthia Hadjidakis

2002-12-01T23:59:59.000Z

46

HDice, Highly-Polarized Low-Background Frozen-Spin HD Targets for CLAS experiments at Jefferson Lab  

Science Conference Proceedings (OSTI)

Large, portable frozen-spin HD (Deuterium-Hydride) targets have been developed for studying nucleon spin properties with low backgrounds. Protons and Deuterons in HD are polarized at low temperatures (~10mK) inside a vertical dilution refrigerator (Oxford Kelvinox-1000) containing a high magnetic field (up to 17T). The targets reach a frozen-spin state within a few months, after which they can be cold transferred to an In-Beam Cryostat (IBC). The IBC, a thin-walled dilution refrigerator operating either horizontally or vertically, is use with quasi-4? detector systems in open geometries with minimal energy loss for exiting reaction products in nucleon structure experiments. The first application of this advanced target system has been used for Spin Sum Rule experiments at the LEGS facility in Brookhaven National Laboratory. An improved target production and handling system has been developed at Jefferson Lab for experiments with the CEBAF Large Acceptance Spectrometer, CLAS.

Wei, Xiangdong [JLAB; Bass, Christopher [JLAB; D'Angelo, Annalisa [INFN-Roma Tor Vegata; Deur, Alexandre P. [JLAB; Dezern, Gary L. [JLAB; Ho, Dao Hoang [Carnegie Mellon U.; Kageya, Tsuneo [JLAB; Khandaker, Mahbubul A, [Idaho State U.; Kashy, David H. [JLAB; Laine, Vivien Eric [Universite de Clermont Ferrand; Lowry, Michael M. [JLAB; O'Connell, Thomas Robert [University of Connecticut; Sandorfi, Andrew M. [JLAB; Teachey, II, Robert W. [JLAB; Whisnant, Charles Steven [James Madison U.; Zarecky, Michael R. [JLAB

2012-12-01T23:59:59.000Z

47

Evidence for an Exotic Baryon State, Theta{sup +}(1540), in Photoproduction Reactions from Protons and Deuterons with CLAS  

DOE Green Energy (OSTI)

CLAS photoproduction data on deuterium and hydrogen targets have been analyzed in a search for an exotic baryon state with strangeness S = +1, the {Theta}{sup +} (originally named the Z{sup +}). This resonance was predicted recently in theoretical work based on the chiral soliton model as a lowest mass member of an anti-decuplet of 5-quark states. The reaction {gamma}d {yields} pK{sup -}K{sup +}n, which requires a final state interaction inside the deuteron, was used in the analysis of deuteron data. In the analysis of proton data, the reaction {gamma}p {yields} {pi}{sup +}K{sup -}K{sup +}n was studied. Evidence for the {Theta}{sup +} state is found in both analyzes in the invariant mass distribution of the nK{sup +}. Our results are consistent with previously reported results by LEPS/Spring-8 collaboration (Japan), and by the ITEP (Moscow) group.

Valery Kubarovsky; Stepan Stepanyan

2003-05-01T23:59:59.000Z

48

The Search for Exotic Mesons in gamma p -> pi+pi+pi-n with CLAS at Jefferson Lab  

E-Print Network (OSTI)

The $\\pi_1(1600)$, a $J^{PC} = 1^{-+}$ exotic meson has been observed by experiments using pion beams. Theorists predict that photon beams could produce gluonic hybrid mesons, of which the $\\pi_1(1600)$ is a candidate, at enhanced levels relative to pion beams. The g12 rungroup at Jefferson Lab's CEBAF Large Acceptance Spectrometer (CLAS) has recently acquired a large photoproduction dataset, using a liquid hydrogen target and tagged photons from a 5.71 GeV electron beam. A partial-wave analysis of 502K $\\gamma p \\to \\pi^+\\pi^+\\pi^-n$ events selected from the g12 dataset has been performed, and preliminary fit results show strong evidence for well-known states such as the $a_1(1260)$, $a_2(1320)$, and $\\pi_2(1670)$. However, we observe no evidence for the production of the $\\pi_1(1600)$ in either the partial-wave intensities or the relative complex phase between the $1^{-+}$ and the $2^{-+}$ (corresponding to the $\\pi_2$) partial waves.

Craig Bookwalter

2011-08-31T23:59:59.000Z

49

The Search for Exotic Mesons in gamma p -> pi+pi+pi-n with CLAS at Jefferson Lab  

DOE Green Energy (OSTI)

The {pi}{sub 1}(1600), a J{sup PC} = 1{sup {-+}} exotic meson has been observed by experiments using pion beams. Theorists predict that photon beams could produce gluonic hybrid mesons, of which the {pi}{sub 1}(1600) is a candidate, at enhanced levels relative to pion beams. The g12 rungroup at Jefferson Lab's CEBAF Large Acceptance Spectrometer (CLAS) has recently acquired a large photoproduction dataset, using a liquid hydrogen target and tagged photons from a 5.71 GeV electron beam. A partial-wave analysis of 502K {gamma}p {yields} {pi}{sup +}{pi}{sup +}{pi}{sup -}n events selected from the g12 dataset has been performed, and preliminary fit results show strong evidence for well-known states such as the a{sub 1}(1260), a{sub 2}(1320), and {pi}{sub 2}(1670). However, we observe no evidence for the production of the {pi}{sub 1}(1600) in either the partial-wave intensities or the relative complex phase between the 1{sup {-+}} and the 2{sup {-+}} (corresponding to the {pi}{sub 2}) partial waves.

Craig Bookwalter

2011-12-01T23:59:59.000Z

50

Results from CLAS and Outlook to CLAS12  

Science Conference Proceedings (OSTI)

In this paper I will illustrate examples of progress in the five main avenues of nucleon structure research in Hall B at JLab: elastic and resonance transition form factors, polarized inelastic scattering, semi-inclusive meson electroproduction, hard exclusive reactions and non-strange baryon spectroscopy. The 12 GeV machine and detector upgrade will offer an unprecedented opportunity to study all these topics in a broader kinematic domain.

Marco Ripani

2010-12-01T23:59:59.000Z

51

Results from CLAS and Outlook to CLAS12  

Science Conference Proceedings (OSTI)

In this paper I will illustrate examples of progress in the five main avenues of nucleon structure research in Hall B at JLab: elastic and resonance transition form factors, polarized inelastic scattering, semi-inclusive meson electroproduction, hard exclusive reactions and non-strange baryon spectroscopy. The 12 GeV machine and detector upgrade will offer an unprecedented opportunity to study all these topics in a broader kinematic domain.

Ripani, M. [INFN Genova, Via Dodecaneso 33, Genova (Italy)

2010-12-22T23:59:59.000Z

52

La Liste Des Tantras Du rNying Ma'i Rgyud 'bum Selon L'edition Et Ablie Par Kun Mkhyen 'Jigs Med Gling Pa  

E-Print Network (OSTI)

‘gro ba’i rgyud lnga) qui sontcommuns à l’Anuyoga24 et dont la liste concerne les nos. 229, 224, 169, 166 etun Ri bo brtsegs pa’i rgyud qui est non-identifié dans la liste de ‘Jigs med glingpa),xvi. le Recueillement Concentré (Ting ‘dzin rtse gcig, non... ’on pourrait leur en trouver une, ainsi qu’on la fait dans cette présentation. Il faudrait également appliquer à ce schéma celui des clas- sification complexes du Klong sde en Abîme blanc (klong dkar po), noir (klong nag po), diapré (klong khra bo) et infini...

Achard, Jean-Luc

2002-01-01T23:59:59.000Z

53

The CLAS Forward Electromagnetic Calorimeter  

E-Print Network (OSTI)

of the daily maintenance schedule. Staff routinely both visually and physically inspect catch basins for debris

Thomas Jefferson National Accelerator Facility

54

Extracting TMDs from CLAS12 data  

Science Conference Proceedings (OSTI)

We present studies of double longitudinal spin asymmetries in semi-inclusive deep inelastic scattering using a new dedicated Monte Carlo generator, which includes quark intrinsic transverse momentum within the generalized parton model based on the fully differential cross section for the process. Additionally we employ Bessel-weighting to the MC events to extract transverse momentum dependent parton distribution functions and also discuss possible uncertainties due to kinematic correlation effects.

Aghasyan, Mher M. [INFN-Frascati; Avakian, Harut A. [JLAB

2014-01-01T23:59:59.000Z

55

Baryon spectroscopy with CLAS at Jefferson Lab  

Science Conference Proceedings (OSTI)

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

Eugene Pasyuk, CLAS Collaboration

2012-04-01T23:59:59.000Z

56

CEBAF Large Acceptance Spectrometer (CLAS) Physics Database  

DOE Data Explorer (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 44 experiments with data that the public can freely access.

None

57

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

Science Conference Proceedings (OSTI)

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.

Fink, Glenn A.; Oehmen, Christopher S.

2012-09-01T23:59:59.000Z

58

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

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.

Baptiste Guegan

2012-11-01T23:59:59.000Z

59

Measurement of Deeply Virtual Compton Scattering (DVCS) cross sections with CLAS  

SciTech Connect

Extraction of DVCS unpolarized and polarized cross sections in the largest kinematic domain ever explored in the valence region. Results are in good agreement with GPD model (VGG) predictions. Extraction of Compton Form Factors (M. Guidal) by fitting simultaneously these unpolarizedand polarized cross sections gives a large set of results in a very large kinematic domain for Re(H ) and Im(H ). Analysis of the data from the second part of the e1-DVCS experiment underway.

Hyon-Suk Jo

2012-04-01T23:59:59.000Z

60

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

Science Conference Proceedings (OSTI)

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

Silvia Niccolai

2012-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "type-of-sale clas sification" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

The use of nested sampling in the extraction of polarisation observables at CLAS  

SciTech Connect

The extraction of polarisation observables from photoproduction experiments provides an insight into the spectrum of nucleon resonances and the 'missing resonance' problem. Experiments carried out at JLab, Mainz and Bonn cover a wide range of reactions, which will soon result in the first 'complete measurement' in pseudoscalar meson photoproduction. Traditionally, these measurements have been analysed using frequentist statistics, where parameters are extracted by fitting distributions. An alternative method is the application of Bayesian statistics, where any existing knowledge about the results can be used in the initial conditions. One such application of this is nested sampling. This work discusses nested sampling and how it can be applied to the extraction of spin observables.

Stefanie Lewis

2012-09-01T23:59:59.000Z

62

Scintillation detector development for the solenoidal tracker at RHIC (STAR) and the CEBAF large acceptance spectrometer (CLAS).  

E-Print Network (OSTI)

??After a brief introduction describing some of the physics and mechanics of scintillation detection, results of the development for the Central Trigger Barrel (CTB) for… (more)

Taylor, Simon John

1996-01-01T23:59:59.000Z

63

Free Extreme Values Gerard Ben Arous and Dan Virgil Voiculescu  

E-Print Network (OSTI)

Free Extreme Values Gerard Ben Arous and Dan Virgil Voiculescu New York University and University at Berkeley Berkeley, CA 94720-3840 E-mail:dvv@math.berkeley.edu Abstract: Free probability analogues- sification of freely max-stable laws and their domains of attraction, using "free extremal convolutions

Ben Arous, Gérard

64

Validating a High-Performance, Programmable Secure ...  

Science Conference Proceedings (OSTI)

... Power Analysis One often encounters reluctance in discussing power analysis due its rumored part of clas- sified TEMPEST. ...

1999-11-05T23:59:59.000Z

65

The Grand Challenge of Managing the Petascale Facility  

E-Print Network (OSTI)

, 2010 ­ p. 1/ #12;CEBAF - The Way It Is. CLAS12 Software Workshop - May 25, 2010 ­ p. 2/ #12;CEBAF Software Workshop - May 25, 2010 ­ p. 4/ #12;A New CEBAF Large Acceptance Spectrometer (CLAS12). The CLAS12

66

Review of Particle Physics  

E-Print Network (OSTI)

Studies for Nuclear Physics CEBAF Je?erson Lab—Thomas Je?by CLAS and PrimEx at CEBAF, and by PANDA at GSI. Recently,

Nakamura, Kenzo

2010-01-01T23:59:59.000Z

67

Photodisintegration of [superscript 4]He into p plus t  

E-Print Network (OSTI)

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 ...

Suleiman, R.

68

Quasi-Periodic Oscillations in a Symmetric General Circulation Model  

Science Conference Proceedings (OSTI)

Long lime integrations with a symmetric version of the CLAS Climate Model with hydrology have shown that the Hadley circulation has well defined strong and weak episodes. This oscillation of the Hadley circulation seems to occur in two dominant ...

B. N. Gyoswami; J. Shukla

1984-01-01T23:59:59.000Z

69

hep-ph/971238815Dec1997 hep-ph/9712388  

E-Print Network (OSTI)

a conventional monopole form for the cut­off form factor Fpn(t) = 2 /(2 - t) with = 1.2 GeV. We take the nucleon.1 GeV, relevant to the CLAS detector at CEBAF. We utilize the standard parameters. Electron Energy is that for the CLAS detector at CEBAF, an electron beam towards the lower end of the range (e.g. 5.5 GeV) appears

Thomas Jefferson National Accelerator Facility

70

Sorption Mechanisms for Mercury Capture in Warm Post-Gasification Gas Clean-Up Systems  

NLE Websites -- All DOE Office Websites (Extended Search)

Sorption MechaniSMS for Mercury Sorption MechaniSMS for Mercury capture in WarM poSt-GaSification GaS clean-up SySteMS Background Power generation systems employing gasification technology must remove a variety of potential air pollutants, including mercury, from the synthetic gas steam prior to combustion. In general, efforts to remove mercury have focused on removal at lower temperatures (under 300 °F). The ability to remove mercury at warm-gas cleanup conditions (300 °F to 700 °F) or in the hot-gas cleanup range (above 1200 °F) would provide plant operators with greater flexibility to choose the treatment method best suited to conditions at their plant. The University of Arizona is investigating the use of paper waste-derived sorbents (PWDS) for the removal of mercury and other trace metals at temperatures in and

71

Photo-Production of Proton Antiproton Pairs  

DOE Green Energy (OSTI)

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

Paul Eugenio; Burnham Stokes

2007-02-01T23:59:59.000Z

72

Photoproduction of proton antiproton resonances  

DOE Green Energy (OSTI)

Preliminary results are reported on the reaction {gamma}p {yields} pp{bar p}. The data were obtained at the Thomas Jefferson National Accelerator Facility utilizing the CLAS detector and a tagged photon beam of 4.8 to 5.2 GeV incident on a liquid hydrogen target. The focus of this study is to search for possible intermediate resonances which decay to {bar p}p. Both final state protons were detected in CLAS whereas the antiproton was identified via missing mass. General features of the accepted data are presented.

P. Eugenio

2004-08-01T23:59:59.000Z

73

Hard Scattering Studies at Jlab  

DOE Green Energy (OSTI)

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.

Harutyun Avagyan; Peter Bosted; Volker Burkert; Latifa Elouadrhiri

2005-09-01T23:59:59.000Z

74

Main line natural gas sales to industrial users: 1978  

Science Conference Proceedings (OSTI)

Main line natural gas sales (in million cubic feet) by interstate natural gas companies to industrial users are itemized for 1974 to 1978. Information includes company name, customer name, customer's Standard Industrial Classification (SIC), the type of sale (where available and applicable), the delivery point, and the state involved in transactions. Tabulations summarize sales by SIC, by state and SIC, and by natural gas companies and SIC. Also summarized in the tables are sales by state and type (offpeak, interruptible, and not specified) for 1978. A brief narrative highlights recent trends and makes comparisons between the two most recent years. 5 tables.

Not Available

1980-01-08T23:59:59.000Z

75

Main line natural gas sales to industrial users, 1980  

Science Conference Proceedings (OSTI)

Main line natural gas sales (in million cubic feet) by interstate natural gas companies to industrial users and other public authorities are itemized for each year from 1976 through 1980. Information includes company name, customer name, customer's Standard Industrial Classification (SIC), the type of sale (where available and applicable), the delivery point, and the state involved in transactions. Tabulations summarize sales by SIC, by State and SIC, and by Natural Gas Companies and SIC. Also summarized in the tables and sales by State and type (offpeak interruptible, and not specified) for 1980 A brief narrative highlights recent trends and makes comparisons between the two most recent years. 5 tables.

Dillard, F.B.

1981-12-01T23:59:59.000Z

76

Main-line natural gas sales to industrial users 1979  

Science Conference Proceedings (OSTI)

Main line natural gas sales by interstate natural gas companies to industrial users are itemized for 1975 to 1979. Information includes company name, customer name, customer's standard industrial classification (SIC), the type of sale (where available), the delivery point, and the state involved in transactions. Tabulations summarize sales by SIC, by state and SIC, and by natural gas companies and SIC. Also summarized are sales by state and type (offpeak, interruptible, and not specified) for the year 1979. An accompanying narrative highlights recent trends and makes comparisons between the two most recent years. 5 tables.

Not Available

1981-02-01T23:59:59.000Z

77

Actes JFPC 2006 CSP dynamiques en configuration  

E-Print Network (OSTI)

Actes JFPC 2006 CSP dynamiques en configuration Article Jeune Chercheur JFPC'06 Thomas van'Albi-Carmaux, Route de Teillet, 81013 Albi Cedex 09 {vanouden, gaborit, aldanond, vareille}@enstimac.fr Résumé Les CSP, la configuration fait ressortir des besoins qui peuvent difficilement être traités par des CSP clas

Paris-Sud XI, Université de

78

Gender Classification from Unconstrained Video Sequences Meltem Demirkus  

E-Print Network (OSTI)

Machines McGill University, Montreal, Canada demirkus@cim.mcgill.ca Matthew Toews Department of RadiologyGill University, Montreal, Canada clark@cim.mcgill.ca Tal Arbel Centre for Intelligent Machines McGill University, Montreal, Canada arbel@cim.mcgill.ca Abstract This paper presents the first investigation into the clas

Clark, James J.

79

Helicity Asymmetry Measurement for pi^0 Photoproduction with FROST  

Science Conference Proceedings (OSTI)

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.

Iwamoto, Hideko [George Washington U.

2011-08-01T23:59:59.000Z

80

Why the Theta+ is seen in some experiments and not in others: A Possible explanation.  

E-Print Network (OSTI)

-ph/0312344. [30] M. Battaglieri [presenting CLAS Coll. data], talk at Pentaquark Workshop, Feb. 10-12, 2004, Trento, Italy, http://www.tp2.ruhr-uni-bochum.de/talks/trento04/battaglieri.pdf . [31] M. Karliner and H. J. Lipkin, Phys. Lett. B 586, 303 (2004) hep...

Karliner, Marek; Lipkin, Harry J

Note: This page contains sample records for the topic "type-of-sale clas sification" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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We encourage you to perform a real-time search of NLEBeta
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81

SPRING 2011 Increased Support for Collaborative  

E-Print Network (OSTI)

, Gender, and Sexuality Studies) Ex-officio Victor Bailey (Hall Center) Ann Cudd (Associate Dean, CLAS) Liz Walzel (Dean, School of Music) Advisory Board Chair, Charles W. Battey (KN Energy, Inc. [Ret.], Overland: Narratives of Gender, Class, and Family in Contemporary Chinese Literature and Culture" #12;The Hall Center

Peterson, Blake R.

82

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

E-Print Network (OSTI)

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

Deselaers, Thomas

83

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

E-Print Network (OSTI)

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

Marco Ripani

1999-02-18T23:59:59.000Z

84

VOLUME 85, NUMBER 17 P H Y S I C A L R E V I E W L E T T E R S 23 OCTOBER 2000 Characterization of Fusion Burn Time in Exploding Deuterium Cluster Plasmas  

E-Print Network (OSTI)

- Department of Physics Software We simulated the neutron detection efficiency of the forward time of flight for this new physics program. Specifically, we are simulating the neutron detection efficiency of the forwardNeutron Detection Efficiency of the CLAS12 Detector M. Moog and G. Gilfoyle University Of Richmond

Ditmire, Todd

85

Neutron Interferometry: Lessons in Experimental Quantum Mechanics Helmut Rauch and Samuel A. Werner  

E-Print Network (OSTI)

University Of Richmond - Department of Physics Software We simulated the neutron detection efficiency physics program. Specifically, we are simulating the neutron detection efficiency of the forward TOFSimulating the Neutron Detection Efficiency of the CLAS12 Detector M. Moog and G. Gilfoyle

Lynn, Jeffrey W.

86

Jefferson Lab | Jefferson Lab  

NLE Websites -- All DOE Office Websites (Extended Search)

News item slideshow News item slideshow Final Piece Final Piece Workers install a section of the pre-shower calorimeter, or PCAL, which is part of the CLAS12 detector package in Jefferson Lab's Experimental Hall B. The new equipment is being installed for the 12 GeV Upgrade project. <<< Installation of PCAL in Hall B. Upgraded Detector Upgraded Detector Work on the 12 GeV Upgrade project continues at Jefferson Lab. Shown here is the new CLAS12 detector in Experimental Hall B after the recent installation of the pre-shower calorimeter, or PCAL. <<< Installation work on Hall B detector. Neutron Stopper Neutron Stopper Jefferson Lab engineer Paul Brindza holds up samples of a new system of concrete products designed to stop neutrons and other particles from harming sensitive scientific computers and detectors. The new system was

87

Evidence for new nucleon resonances from electromagnetic meson production  

Science Conference Proceedings (OSTI)

The study of nucleon resonances in electromagnetic meson production with the CLAS detector is discussed. The electromagnetic interaction is complementary to pion scattering in the exploration of the nucleon excitation spectrum. Higher mass states often decouple from the N{pi} channel and are not seen in {pi} N --> {pi} N. Photoproduction of mesons, such as K {Lambda}, {omega} p and {eta}' p may be more sensitive to many of these states. The CLAS detector, combined with the use of energy-tagged polarized photons and polarized electrons, as well as po- larized targets and the measurement of recoil polarization, are the tools needed for a comprehensive nucleon resonance program. Some of the recently published high statistics data sets had significant impact on further clarifying the nucleon excitation spectrum.

Volker Burkert

2012-12-01T23:59:59.000Z

88

Studies of Nucleon Resonance Structure in Exclusive Meson Electroproduction  

SciTech Connect

The studies of N* structure represent a key direction in the N* Program with CLAS detector. After 12 GeV Upgrade, the dedicated experiment on the studies of N* structure at largest photon virtualities ever achieved Q^2<12 GeV^2 is scheduled for the first year of running with the CLAS12 detector. The current status and plans for theory support of the N* structure studies in exclusive meson electroproduction are presented. They include the recent advances in the reaction theory for extraction of N* electrocouplings from the data and the approaches for high level theoretical interpretation of these fundamental quantities, allowing us to access dynamics of non-perturbative strong interaction which is responsible for the resonance formation and explore how it emerges from QCD.

Aznauryan, Inna G. [Yerevan Physics Institute, JLAB; Bashir, Adnan; Braun, Vladimir M.; Brodsky, Stanley J. [SLAC; Burkert, Volker D. [JLAB; Chang, L.; Chen, Ch.; El-Bennich, Bruno O.; Cloet, Ian C.; Cole, Philip L. [Idaho State U.; Edwards, Robert G. [JLAB; Fedotov, Gleb V. [South Carolina U.; Giannini, Mauro M.; Gothe, Ralf W. [South Carolina U.; Lin, Huey-Wen [Washington; Kroll, Peter; Lee, T.-S. H.; Melnitchouk, Wally [JLAB; Mokeev, Viktor I [JLAB; Pena, Maria Teresa [CFTP; Ramalho, Gilberto T.F. [CFTP; Roberts, Craig D. [ANL; Santopinto, Elena; De Teramond, Guy F.; Tsushima, Kazuo [Adelaide U.; Wilson, David J. [Old Dominion U.

2013-06-01T23:59:59.000Z

89

Progress on Neutron-Target Multipoles above 1 GeV  

SciTech Connect

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

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

2012-12-01T23:59:59.000Z

90

Polarization Measurements in Photoproduction with CEBAF Large Acceptance Spectrometer  

Science Conference Proceedings (OSTI)

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.

E. Pasyuk

2010-05-01T23:59:59.000Z

91

Measurement of the Neutron Magnetic Form Factor at Using the Ratio Method on Deuterium  

E-Print Network (OSTI)

the magnetic form factor of the neutron using the 11 GeV electron beam in the upgraded CEBAF and CLAS12 to the higher Q2 that will be available with the 12-GeV upgrade of CEBAF. We will use the ratio]). With the 12-GeV upgrade of CEBAF, Gp E/Gp M and Gn M can be measured up to Q2 14 GeV2 and for Gn E up to Q2

Gilfoyle, Jerry

92

University of Richmond Department of Physics  

E-Print Network (OSTI)

of the transition between the Hadronic Model and the QCD theory. 11 2-6 GeV; #12;7 CEBAF 10 7 CEBAF CEBAF of different types of particle detectors. Fig. 5: The CLAS detector [11]. #12;8 CEBAF Large Acceptance at beam energy 2.56GeV, reversed12 torus polarity, was conducted in order to reach a low Q2. Our research

Gilfoyle, Jerry

93

Experimental Medium Energy Physics. Annual progress report, June 1991--May 1992  

SciTech Connect

This report discusses the following topics: Search for the H Dibaryon at the AGS; hypernuclear weak decay studies at the LAGS; search for strangelets using the 2 GeV/c beam line; experiment to detect double lambda hypernuclei; hyperon photoproduction at CEBAF; the region 1 drift chambers for the CLAS spectrometer; parity violating electron scattering from the proton: the G{sup 0}experiment at CEBAF; and relativistic heavy ion - nucleus collisions at the SPS.

1992-09-01T23:59:59.000Z

94

X:\L6046\Data_Publication\Pma\current\ventura\pma.vp  

Gasoline and Diesel Fuel Update (EIA)

gasoline gasoline in individual transactions which exceed the size of a truckload. CIF: Cost, insurance, and freight. A type of sale in which the buyer of the product agrees to pay a unit price that includes the f.o.b. value of the product at the point of origin plus all costs of insurance and transpor- tation. This type of transaction differs from a "deliv- ered" purchase, in that the buyer accepts the quantity as determined at the loading port (as certified by the bill of loading and quality report) rather than pay based on the quantity and quality ascertained at the unload- ing port. It is similar to the terms of an f.o.b. sale, except that the seller, as a service for which he is compensated, arranges for transportation and insurance. Commercial Sector: An energy-consuming sector that consists of service-providing facilities and equipment of businesses; Federal, State, and local governments;

95

Nucleon Structure Studies with Electromagnetic Probes  

Science Conference Proceedings (OSTI)

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

Vineyard, Michael F.

2011-03-31T23:59:59.000Z

96

ASC-eNews-December-2009.indd  

National Nuclear Security Administration (NNSA)

3 SAND 2009-8321 W 3 SAND 2009-8321 W December 2009 The Meisner Minute Editorial by Bob Meisner As we approach the end of 2009 and approach a lull in Washington budget activities, it seems an appropriate time to reflect on tri-lab achievements. Over the past year, platform activities continued to provide new challenges and ground-breaking results. Roadrunner completed its shakedown period; not only is it ready to transition to clas- sified operations, nine science projects produced results that are being published in technical

97

Chiral Restoration in the Nuclear Medium  

SciTech Connect

The photoproduction of vector mesons on various nuclei has been studied using the CLAS detector at Jefferson Laboratory. The vector mesons, rho, omega, and [cursive phi], are observed via their decay to e+e?, in order to reduce the effects of final state interactions in the nucleus. Of particular interest are possible in-medium effects on the properties of the rho meson. The rho mass spectrum is extracted from the data on various nuclei, D2, C, Fe, and Ti. We observe no significant mass shift and some broadening consistent with expected collisional broadening for the rho meson.

C. Djalali; R. Nasseripour; D. P. Weygand; M. H. Wood

2007-10-01T23:59:59.000Z

98

Are there approximate relations among transverse momentum dependent distribution functions?  

SciTech Connect

Certain {\\sl exact} relations among transverse momentum dependent parton distribution functions due to QCD equations of motion turn into {\\sl approximate} ones upon the neglect of pure twist-3 terms. On the basis of available data from HERMES we test the practical usefulness of one such ``Wandzura-Wilczek-type approximation'', namely of that connecting $h_{1L}^{\\perp(1)a}(x)$ to $h_L^a(x)$, and discuss how it can be further tested by future CLAS and COMPASS data.

Harutyun AVAKIAN; Anatoli Efremov; Klaus Goeke; Andreas Metz; Peter Schweitzer; Tobias Teckentrup

2007-10-11T23:59:59.000Z

99

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

SciTech Connect

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

Chaden Djalali

2011-12-01T23:59:59.000Z

100

Studies of spin-orbit correlations at JLAB  

Science Conference Proceedings (OSTI)

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

Mher Aghasyan, Harut Avakian

2011-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "type-of-sale clas sification" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

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

DOE Green Energy (OSTI)

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 {phi}{sub h} amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle {phi}{sub h} of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations.

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

2011-10-25T23:59:59.000Z

102

Complete measurement of three-body photodisintegration of 3He for photon energies between 0.35 and 1.55 GeV  

E-Print Network (OSTI)

The three-body photodisintegration of 3He has been measured with the CLAS detector at Jefferson Lab, using tagged photons of energies between 0.35 GeV and 1.55 GeV. The large acceptance of the spectrometer allowed us for the first time to cover a wide momentum and angular range for the two outgoing protons. Three kinematic regions dominated by either two- or three-body contributions have been distinguished and analyzed. The measured cross sections have been compared with results of a theoretical model, which, in certain kinematic ranges, have been found to be in reasonable agreement with the data.

CLAS Collaboration; S. Niccolai; G. Audit; B. L. Berman; J. M. Laget; S. Strauch

2004-09-16T23:59:59.000Z

103

Beam Spin Asymmetry Measurements from Deeply Virtual Meson Production  

DOE Green Energy (OSTI)

Study of deeply virtual exclusive meson production (DVMP), is being conducted in the E1-DVCS experiment with the CLAS detector at Jefferson Lab. The main motivation of the experiment is to characterize the partonic properties of the nucleon in the framework of generalized parton distributions (GPDs). The data were taken in the spring of 2005 using a 5.7 GeV longitudinally polarized electron beam and an unpolarized hydrogen target. We report on the on-going beam spin asymmetry analysis for pseudo-scalar channels and future experiments.

K. Joo; R. De Masi; M. Garcon; V. Kubarovsky; P. Stoler; M. Ungaro; B. Zhao

2007-06-01T23:59:59.000Z

104

Deeply Virtual Exclusive Processes and Generalized Parton Distributions  

SciTech Connect

The goal of the comprehensive program in Deeply Virtual Exclusive Scattering at Jefferson Laboratory is to create transverse spatial images of quarks and gluons as a function of their longitudinal momentum fraction in the proton, the neutron, and in nuclei. These functions are the Generalized Parton Distributions (GPDs) of the target nucleus. Cross section measurements of the Deeply Virtual Compton Scattering (DVCS) reaction ep {yields} ep{gamma} in Hall A support the QCD factorization of the scattering amplitude for Q^2 {>=} 2 GeV^2. Quasi-free neutron-DVCS measurements on the Deuteron indicate sensitivity to the quark angular momentum sum rule. Fully exclusive H(e, e'p{gamma} ) measurements have been made in a wide kinematic range in CLAS with polarized beam, and with both unpolarized and longitudinally polarized targets. Existing models are qualitatively consistent with the JLab data, but there is a clear need for less constrained models. Deeply virtual vector meson production is studied in CLAS. The 12 GeV upgrade will be essential for for these channels. The {rho} and {omega} channels reactions offer the prospect of flavor sensitivity to the quark GPDs, while the {phi}-production channel is dominated by the gluon distribution.

,

2011-06-01T23:59:59.000Z

105

CLARA: A Contemporary Approach to Physics Data Processing  

SciTech Connect

In traditional physics data processing (PDP) systems, data location is static and is accessed by analysis applications. In comparison, CLARA (CLAS12 Reconstruction and Analysis framework) is an environment where data processing algorithms filter continuously flowing data. In CLARA's domain of loosely coupled services, data is not stored, but rather flows from one service to another, mutating constantly along the way. Agents, performing event processing, can then subscribe to particular data/events at any stage of the data transformation, and make intricate decisions (e.g. particle ID) by correlating events from multiple, parallel data streams and/or services. This paper presents a PDP application development framework based on service oriented and event driven architectures. This system allows users to design (Java, C++, and Python languages are supported) and deploy data processing services, as well as dynamically compose PDP applications using available services. The PDP service bus provides a layer on top of a distributed pub-sub middleware implementation, which allows complex service composition and integration without writing code. Examples of service creation and deployment, along with the CLAS12 track reconstruction application design will be presented.

V Gyurjyan, D Abbott, J Carbonneau, G Gilfoyle, D Heddle, G Heyes, S Paul, C Timmer, D Weygand, E Wolin

2011-12-01T23:59:59.000Z

106

US COALBED METHANE The Past: Production The Present: Reserves  

U.S. Energy Information Administration (EIA) Indexed Site

Panel 2 of 2 Panel 2 of 2 US COALBED METHANE The Past: Production The Present: Reserves The Future: Resources Annual coalbed methane gas production data through 12/31/2006 was obtained from 17 state oil & gas regulatory entities or geological surv eys and one producing company. Data for 2006 were not yet av ailable for West Virginia and Pennsy lvania so the 2005 v olumes were assumed to repeat in 2006. Produced CBM gas v olumes from each state were clas sified by basin. The cumulative production pie chart to the left shows the sum of all reported CBM gas volumes by basin through 2006. The San Juan Bas in dominates the chart. The only other bas in to ex ceed 10% is the Pow der River Basin (12%). Relative cumulative production volumes by basin are spatially depicted in the c

107

Kinematic Fitting of Detached Vertices  

SciTech Connect

The eg3 experiment at the Jefferson Lab CLAS detector aims to determine the existence of the $\\Xi_{5}$ pentaquarks and investigate the excited $\\Xi$ states. Specifically, the exotic $\\Xi_{5}^{--}$ pentaquark will be sought by first reconstructing the $\\Xi^{-}$ particle through its weak decays, $\\Xi^{-}\\to\\pi^{-}\\Lambda$ and $\\Lambda\\to\\pi^{-}$. A kinematic fitting routine was developed to reconstruct the detached vertices of these decays, where confidence level cuts on the fits are used to remove background events. Prior to fitting these decays, the exclusive reaction $\\gamma D\\rightarrow pp\\pi^{-}$ was studied in order to correct the track measurements and covariance matrices of the charged particles. The $\\Lambda\\rightarrow p\\pi^{-}$ and $\\Xi^{-}\\to\\pi^{-}\\Lambda$ decays were then investigated to demonstrate that the kinematic fitting routine reconstructs the decaying particles and their detached vertices correctly.

Paul Mattione

2007-05-01T23:59:59.000Z

108

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

SciTech Connect

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

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

2011-04-01T23:59:59.000Z

109

Single pion electro-- and neutrinoproduction on heavy targets  

E-Print Network (OSTI)

We present a calculation of single pion electroproduction cross sections on heavy targets in the kinematic region of the Delta(1232) resonance. Final state interactions of the pions are taken into account using the pion multiple scattering model of Adler, Nussinov and Paschos (ANP model). For electroproduction and neutral current reactions we obtain results for carbon, oxygen, argon and iron targets and find a significant reduction of the W-spectra for pi^0 as compared to the free nucleon case. On the other hand, the charged pion spectra are only little affected by final state interactions. Measurements of such cross sections with the CLAS detector at JLAB could help to improve our understanding of pion rescattering effects and serve as important/valuable input for calculations of single pion neutrinoproduction on heavy targets relevant for current and future long baseline neutrino experiments. Two ratios, in Eq. (3.8) and (3.10), will test important properties of the model.

Paschos, E A; Yu, J -Y

2007-01-01T23:59:59.000Z

110

Single pion electro-- and neutrinoproduction on heavy targets  

E-Print Network (OSTI)

We present a calculation of single pion electroproduction cross sections on heavy targets in the kinematic region of the Delta(1232) resonance. Final state interactions of the pions are taken into account using the pion multiple scattering model of Adler, Nussinov and Paschos (ANP model). For electroproduction and neutral current reactions we obtain results for carbon, oxygen, argon and iron targets and find a significant reduction of the W-spectra for pi^0 as compared to the free nucleon case. On the other hand, the charged pion spectra are only little affected by final state interactions. Measurements of such cross sections with the CLAS detector at JLAB could help to improve our understanding of pion rescattering effects and serve as important/valuable input for calculations of single pion neutrinoproduction on heavy targets relevant for current and future long baseline neutrino experiments. Two ratios, in Eq. (3.8) and (3.10), will test important properties of the model.

E. A. Paschos; I. Schienbein; J. -Y. Yu

2007-04-16T23:59:59.000Z

111

Beam asymmetry for pi+ and pi0 photoproduction on the proton for photon energies from 1.102 to 1.862 GeV  

E-Print Network (OSTI)

Beam asymmetries for the reactions gamma p -> p pi0 and gamma p -> n pi+ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged, linearly polarized photon beam with energies from 1.102 to 1.862 GeV. A Fourier moment technique for extracting beam asymmetries from experimental data is described. The results reported here possess greater precision and finer energy resolution than previous measurements. Our data for both pion reactions appear to favor the SAID and Bonn-Gatchina scattering analyses over the older Mainz MAID predictions. After incorporating the present set of beam asymmetries into the world database, exploratory fits made with the SAID analysis indicate that the largest changes from previous fits are for properties of the Delta(1700) 3/2- and Delta(1905) 5/2+ states.

M. Dugger; B. G. Ritchie; P. Collins; E. Pasyuk; W. J. Briscoe; I. I. Strakovsky; R. L. Workman; Y. Azimov

2013-08-19T23:59:59.000Z

112

Probing the nucleon structure with SIDIS at Jefferson Lab  

Science Conference Proceedings (OSTI)

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

Pereira, Sergio Anafalos [INFN-Frascati

2013-01-01T23:59:59.000Z

113

The In-medium Mass and Widths of Light Vector Mesons  

Science Conference Proceedings (OSTI)

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

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

2011-05-23T23:59:59.000Z

114

Photoproduction of hyperon resonances on hydrogen  

DOE Green Energy (OSTI)

We present the current status of our work on the extraction of cross sections and polarizations for photoproduction of hyperon resonances on a hydrogen target (pK+Y*) using existing data from the CEBAF Large Acceptance Spectrometer (CLAS). The cross sections and polarizations will be used for a simultaneous theoretical analysis of hyperon ground state and hyperon resonance production. Thus far we have identified the hyperon resonances 0(1385), (1405), and (1520) through missing mass and invariant mass cuts in various decay channels, such as 0, +-, 00, +-, -+, pK- and nK0. We have not yet seen the resonances (1600), (1660), (1670), (1670) and (1690), although they need to be included for the analysis of the hyperon ground state production.

Henry Juengst

2001-08-01T23:59:59.000Z

115

Search for the Theta+ in photoproduction on the deuteron  

SciTech Connect

A high-statistics experiment on a deuterium target was performed using a real photon beam with energies up to 3.6 GeV at the CLAS detector of Jefferson Lab. The reaction reported here is for {gamma}d {yields} pK{sup -} K{sup +} n where the neutron was identified using the missing mass technique. No statistically significant narrow peak in the mass region from 1.5-1.6 GeV was found. An upper limit on the elementary process {gamma}n {yields} K{sup -} {Theta}{sup +} was estimated to be about 4-5 nb, using a model-dependent correction for rescattering determined from {Lambda}(1520) production. Other reactions with less model-dependence are being pursued.

K.H. Hicks

2005-07-26T23:59:59.000Z

116

Moments of F{sub 2} Structure Functions and Multiparton Correlations in Nuclei  

DOE Green Energy (OSTI)

The inclusive inelastic electron scattering o the proton was measured at five different beam energies 1.5, 2.5, 4.0, 4.2 and 4.4 GeV. The data were taken, during February-March 1999, on a liquid hydrogen target with the CLAS detector installed in Hall-B of the Thomas Jefferson National Accelerator Facility (TJNAF). The obtained high statistics and high precision data appear to be in good agreement with previously measured world data and permit to integrate experimental values of F{sub 2} over x at fixed Q{sup 2} , allowing for the first time the evaluation of its experimental moments at low and moderate values of Q{sup 2} . In a combined analysis of CLAS and world data, the Q{sup 2} -evolution of the experimental moments was explored in the range from 0.3 up to 100 GeV{sup 2} . This offered a unique possibility to trace changes of the proton structure function from hard DIS down to the non-perturbative regime through the transition region, which is of particular interest for the TJNAF physics program. The obtained experimental moments allowed to perform a separation between the leading twist, calculable in the framework of the perturbative QCD (pQCD), and higher twists, treated effectively. A comparison with theoretical predictions based either on lattice QCD simulations or obtained within models of the nucleon structure may represent an important test of our understanding of the nucleon structure as observed at large wavelengths.

Mikhail Osipenko

2002-10-01T23:59:59.000Z

117

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

SciTech Connect

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.

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

1995-12-31T23:59:59.000Z

118

Study of the Two-pion Photoproduction on the Deuteron  

SciTech Connect

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.

Graham, Lewis P. [South Carolina U.

2012-12-01T23:59:59.000Z

119

UCLA Intermediate Energy Nuclear and Particle Physics Research: Final Report  

SciTech Connect

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

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

2011-05-18T23:59:59.000Z

120

Energy Blog | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

July 24, 2013 July 24, 2013 By applying pressure to the generator, one is able to generate about six nanoamperes of current and 400 millivolts of potential -- roughly a quarter of the voltage of a AAA battery and enough to flash a number on the small LCD screen. | Photo courtesy of Seung-Wuk Lee's lab at Lawrence Berkeley National Laboratory. R&D 100: Battery Technology Goes Viral Learn how Energy Department researchers are harnessing power from an unlikely source -- viruses. July 24, 2013 If you've ever heard the thunderous sound of a sonic boom, you've experienced the shock waves in the air created by an object traveling faster than the speed of sound. But what happens when an object travels faster than the speed of light? At Jefferson Laboratory, construction is underway to upgrade the Continuous Electron Beam Accelerator Facility (CEBAF) and the CEABF Large Acceptance Spectrometer (CLAS12) at Hall B. During the experiments, the accelerator will shoot electrons at speeds faster than the speed at which light travels in the same medium, creating shock waves that emit a blue light, known as Cherenkov light -- this light is equivalent to the sonic boom. By recording data from Cherenkov light, scientists will be able to map a nucleon's three-dimensional spin.

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121

Photo of the Week: Faster than the Speed of Light | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Photo of the Week: Faster than the Speed of Light Photo of the Week: Faster than the Speed of Light Photo of the Week: Faster than the Speed of Light July 24, 2013 - 2:00pm Addthis If you've ever heard the thunderous sound of a sonic boom, you've experienced the shock waves in the air created by an object traveling faster than the speed of sound. But what happens when an object travels faster than the speed of light? At Jefferson Laboratory, construction is underway to upgrade the Continuous Electron Beam Accelerator Facility (CEBAF) and the CEABF Large Acceptance Spectrometer (CLAS12) at Hall B. During the experiments, the accelerator will shoot electrons at speeds faster than the speed at which light travels in the same medium, creating shock waves that emit a blue light, known as Cherenkov light -- this light is equivalent to the sonic boom. By recording data from Cherenkov light, scientists will be able to map a nucleon's three-dimensional spin.

122

Page  

NLE Websites -- All DOE Office Websites (Extended Search)

2 2 Θ(1540) + I (J P ) = 0(? ? ) OMITTED FROM SUMMARY TABLE A REVIEW GOES HERE - Check our WWW List of Reviews NODE=B152 Θ(1540) + MASS Θ(1540) + MASS Θ(1540) + MASS Θ(1540) + MASS NODE=B152205 The note below, from the 2006 Review, lists 10 papers on searches for NODE=B152205 the Θ(1540) with negative results. Since then, there have been six more such papers (four of them from the CLAS experiment): AKTAS 06B, DEVITA 06, KUBAROVSKY 06, LINK 06C, MCKINNON 06, and NIC- COLAI 06. Two other papers, MIWA 06 and PANZARASA 06, did find a peak at about the right mass, but only at the 2.5-to-2.7 standard deviation level. We will summarize all these results in a table in the 2008 Review. Since our 2004 edition, there have been several new claimed sightings of the Θ(1540) + (see entries below marked with bars to the right), but there have also been several searches with negative results: * ANTIPOV 04 (SPHINX Collab.)

123

Recent News from the National Labs | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

24, 2013 24, 2013 By applying pressure to the generator, one is able to generate about six nanoamperes of current and 400 millivolts of potential -- roughly a quarter of the voltage of a AAA battery and enough to flash a number on the small LCD screen. | Photo courtesy of Seung-Wuk Lee's lab at Lawrence Berkeley National Laboratory. R&D 100: Battery Technology Goes Viral Learn how Energy Department researchers are harnessing power from an unlikely source -- viruses. July 24, 2013 If you've ever heard the thunderous sound of a sonic boom, you've experienced the shock waves in the air created by an object traveling faster than the speed of sound. But what happens when an object travels faster than the speed of light? At Jefferson Laboratory, construction is underway to upgrade the Continuous Electron Beam Accelerator Facility (CEBAF) and the CEABF Large Acceptance Spectrometer (CLAS12) at Hall B. During the experiments, the accelerator will shoot electrons at speeds faster than the speed at which light travels in the same medium, creating shock waves that emit a blue light, known as Cherenkov light -- this light is equivalent to the sonic boom. By recording data from Cherenkov light, scientists will be able to map a nucleon's three-dimensional spin.

124

Measurement of Exclusive $?^0$ Electroproduction Structure Functions and their Relationship to Transverse Generalized Parton Distributions  

SciTech Connect

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.

Bedlinskiy, Ivan; Niccolai, Silvia; Stoler, Paul; Adhikari, Krishna; Aghasyan, Mher; Amaryan, Moskov; Anghinolfi, Marco; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Ball, Jacques; Baltzell, Nathan; Battaglieri, Marco; Bennett, Robert; Biselli, Angela; Bookwalter, Craig; Boyarinov, Sergey; Briscoe, William; Brooks, Williams; Burkert, Volker; Carman, Daniel; Celentano, Andrea; Chandavar, Shloka; Charles, Gabriel; Contalbrigo, Marco; Crede, Volker; D'Angelo, Annalisa; Daniel, Aji; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Deur, Alexandre; Djalali, Chaden; Doughty, David; Dupre, Raphael; Egiyan, Hovanes; El Alaoui, Ahmed; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Fegan, Stuart; Fleming, Jamie; Forest, Tony; Garcon, Michel; Gevorgyan, Nerses; Giovanetti, Kevin; Girod, Francoi-Xavier; Gohn, Wesley; Gothe, Ralf; Graham, Lewis; Griffioen, Keith; Guegan, Baptiste; Guidal, Michel; Guo, Lei; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Heddle, David; Hicks, Kenneth; Holtrop, Maurik; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Jo, Hyon-Suk; Joo, Kyungseon; Keller, Dustin; Khanddaker, Mahbubul; Khertarpal, Puneet; Kim, Andrey; Kim, Wooyoung; Klein, Franz; Koirala, Suman; Kubarovsky, A; Kuhn, Sebastian; Kuleshov, Sergey; Kvaltine, Nicholas; Livingston, Kenneth; Lu, Haiyun; MacGregor, Ian; Mao, Yuqing; Markov, Nikolai; Martinez, D; Mayer, Michael; McKinnon, Bryan; Meyer, Curtis; Mineeva, Taisiya; Mirazita, Marco; Mokeev, Viktor; Moutarde, Herve; Munevar Espitia, Edwin; Munoz Camacho, Carlos; Nadel-Turonski, Pawel; Niculescu, Gabriel; Niculescu, Maria-Ioana; Osipenko, Mikhail; Ostrovidov, Alexander; Pappalardo, Luciano; Permuzyan, Rafayel; Park, Kijun; Park, Sungkyun; Pasyuk, Eugene; Pereira, Sergio; Phelps, Evan; Pisano, Silvia; Pogorelko, Oleg; Pozdnyakov, Sergey; Price, John; Procureur, Sebastien; Prok, Yelena; Protopopescu, Dan; Puckett, Andrew; Raue, Brian; Ricco, Giovanni; Rimal, Dipak; Ripani, Marco; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Saini, Mukesh; Salgado, Carlos; Saylor, Nicholas; Schott, Diane; Schumacher, Reinhard; Seder, Erin; Seraydaryan, Heghine; Sharabian, Youri; Smith, Gregory; Sober, Daniel; Sokhan, Daria; Stepanyan, Samuel; Strauch, Steffen; Taiuti, Mauro; Tang, Wei; Taylor, Charles; Tian, Ye; Tkachenko, Svyatoslav; Ungaro, Maurizio; Vineyard, Michael; Vlasov, Alexander; Voskanyan, Hakob; Voutier, Eric; Walford, Natalie; Watts, Daniel; Weinstein, Lawrence; Weygan, Dennis; Wood, Michael; Zachariou, Nicholas; Zhang, Jixie; Zhao, Zhiwen

2012-09-01T23:59:59.000Z

125

Polarized structure function sigma_lt' for kaon electroproduction in the nucleon resonance region  

SciTech Connect

The first measurements of the polarized structure function $\\sigma_{LT'}$ for the reaction $p(\\vec e,e'K^+)\\Lambda$ in the nucleon resonance region are reported. Measurements are included from threshold up to $W$=2.05~GeV for central values of $Q^2$ of 0.65 and 1.00~GeV$^2$, and nearly the entire kaon center-of-mass angular range. $\\sigma_{LT'}$ is the imaginary part of the longitudinal-transverse response and is expected to be sensitive to interferences between competing intermediate $s$-channel resonances, as well as resonant and non-resonant processes. The results for $\\sigma_{LT'}$ are comparable in magnitude to previously reported results from CLAS for $\\sigma_{LT}$, the real part of the same response. An intriguing sign change in $\\sigma_{LT'}$ is observed in the high $Q^2$ data at $W\\approx 1.9$~GeV. Comparisons to several existing model predictions are shown.

Rakhsha Nasseripour; B. Raue; Daniel Carman; Pawel Ambrozewicz

2008-02-19T23:59:59.000Z

126

Eta(547) and Eta(958) Meson Photoproduction on the Proton  

DOE Green Energy (OSTI)

Photoproduction of {eta} and {eta}{prime} mesons has been studied at the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) using a tagged photon beam incident on a hydrogen target with photon energies from the respective production thresholds up to 2.4 GeV. The photoproduced mesons were identified via missing mass reconstruction using recoil proton momentum and time of flight information. Data were obtained in a range of {radical}s from threshold to 2.2 GeV for each meson. In this study, differential cross-section measurements for the {gamma}p {yields} p{eta} and {gamma}p {yields} p{eta}{prime} reactions are presented, and the results compared to recent data. An isobar analysis of the differential cross-sections is performed. The predicted differential cross-sections from the isobar analysis are used to predict behavior in unmeasured regions of phase space, and to infer total cross sections. For the {gamma}p {yields} p{eta} reaction, a value of the S{sub 11}(1535) proton helicity amplitude also was extracted and compared to recent analyses. The data presented greatly extends the energy and angle coverage for differential cross-sections of {eta} photoproduction, and significantly improves the accuracy with which {eta}{prime} cross sections are known.

Michael Dugger

2001-12-01T23:59:59.000Z

127

Studies of Hadronization Mechanisms using Pion Electroproduction in Deep Inelas tic Scattering from Nuclei  

SciTech Connect

Atomic nuclei can be used as spatial analyzers of the hadronization process in semi-inclusive deep inelastic scattering. The study of this process using fully-identified final state hadrons began with the HERMES program in the late 1990s, and is now continuing at Jefferson Lab. In the measurement described here, electrons and positive pions were measured from a 5 GeV electron beam incident on targets of liquid deuterium, C, Fe, and Pb using CLAS in Hall B. The broadening of the transverse momentum of positive pions has been studied in detail as a function of multiple kinematic variables, and interpreted in terms of the transport of the struck quark through the nuclear systems. New insights are being obtained into the hadronization process from these studies; and experiments of this type can be relevant for the interpretation of jet quenching and proton-nucleus collisions at RHIC and LHC. These measurements will be extended in the next few years with the approved Jlab experiment E12-06-117, and later at a future Electron-Ion Collider.

Will Brooks, Hayk Hakobyan, Cristian Peña, Miguel Arratia, Constanza Valdés

2012-04-01T23:59:59.000Z

128

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

Science Conference Proceedings (OSTI)

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

Yordanka Ilieva

2011-05-01T23:59:59.000Z

129

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

Science Conference Proceedings (OSTI)

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

Kijun Park

2012-04-01T23:59:59.000Z

130

Light Vector Mesons in the Nuclear Medium  

E-Print Network (OSTI)

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

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

2008-03-04T23:59:59.000Z

131

Photoproduction of K* meson off the proton target with the Regge contributions  

E-Print Network (OSTI)

We investigate the K* Lambda(1116) photoproduction off the proton target, employing the tree-level Born approximation within the effective Lagrangian approach. We take into account the kappa, K, and K* exchanges in the t channel in addition to the ground-state nucleon- and hyperon-pole contributions in the s and u channels with the gauge-invariant form-factor scheme. The nucleon and hyperon resonances, D_13(2080) and Sigma*(1385) are also included. We take into account the Regge trajectories of the strange-mesons for the t-channel contributions in such a way that the Feynman and Regge propagators are interpolated smoothly for the relevant photon energy region. We provide numerical results for the differential cross sections, which result in qualitatively good agreement with the presently available experimental data from CLAS collaboration at Jefferson laboratory. It turns out that the Feynman-Regge interpolation for the meson exchanges play a critical role in reproducing the data simultaneously for the low and relatively high energy regions. We also compute the total cross sections, momentum-transfer dependence of the differential cross sections in the t-channel, and the photon-beam asymmetry as useful guides for future experiments.

Seung-il Nam; Byung-Geel Yu

2011-09-15T23:59:59.000Z

132

Delta Electroproduction in 12-C  

Science Conference Proceedings (OSTI)

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

Steven McLauchlan

2003-01-31T23:59:59.000Z

133

Polarization Observables for Kaon Photoproduction from Polarized Protons  

E-Print Network (OSTI)

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

Natalie K. Walford; Franz J. Klein

2013-12-20T23:59:59.000Z

134

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

SciTech Connect

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

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

1993-06-01T23:59:59.000Z

135

Electroproduction of {rho}{sup 0} mesons on protons in quasielastic kinematics at intermediate energies and spin-flip mechanism of direct meson knockout  

Science Conference Proceedings (OSTI)

It is shown that the amplitude for the direct knockout of {rho}{sup 0} mesons plays an important role at energies W above the resonance region, W {>=} 2 GeV, and rather high values of Q{sup 2} {>=} 1.5-2 GeV{sup 2}/c{sup 2} and that it corresponds to the t pole in the channel of the virtual decay p {sup {yields}}p + {pi}{sup 0} accompanied by quark-spin flip upon momentum transfer to the meson, {pi}{sup 0} + {gamma}*{sub T} {sup {yields} {rho}0}. The contributions of several scalar mesons (p {sup {yields}}p + f{sub 0} channel), the contribution of the tensor meson f{sub 2}, and effects of the interference between different contributions were taken into account in addition to the contribution of the {pi}{sup 0} meson. The vectorand tensor-meson-dominance models were used to estimate the respective vertex constants. Within the proposed mechanism, the differential cross sections d{sigma}{sub L}/dt and d{sigma}{sub T}/dt were calculated for several W and Q{sup 2} values at which the respective total cross sections were measured by the CLAS Collaboration. Agreement with data on the transverse part of the total cross section, {sigma}{sub T}, was attained, whereby the assumption of a dominant role of magnetic spin transitions in the meson skin of the nucleon under conditions of quasielastic-knockout kinematics is confirmed. At the same time, the contribution of spin-flip transitions is suppressed in the longitudinal part of the cross section, {sigma}{sub L}, and this is confirmed by the results of our calculations. The behavior of the differential cross section d{sigma}{sub T}/dt is predicted with an eye to future experiments.

Obukhovsky, I. T., E-mail: obukh@nucl-th.sinp.msu.ru; Neudatchin, V. G.; Sviridova, L. L.; Fedorov, D. K., E-mail: feddk@nucl-th.sinp.msu.r [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

2010-09-15T23:59:59.000Z

136

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

SciTech Connect

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

Nicholas Zachariou

2012-05-20T23:59:59.000Z

137

[Electromagnetic studies of nuclear structure and reactions]. [Nuclear Physics Group, Univ. of New Hampshire  

SciTech Connect

The experimental goals are focused on developing an understanding of strong interactions and the structure of hadronic systems by determination of the electromagnetic response; these goals will be accomplished through coincidence detection of final states. Nuclear modeling objectives are to organize and interpret the data through a consistent description of a broad spectrum of reaction observables; calculations are performed in a nonrelativistic diagrammatic framework as well as a relativistic QHD approach. Work is described according to the following arrangement: direct knockout reactions (completion of [sup 16]O(e,e[prime]p), [sup 12]C(e,e[prime]pp) progress, large acceptance detector physics simulations), giant resonance studies (intermediate-energy experiments with solid-state detectors, the third response function in [sup 12]C(e,e[prime]p[sub 0]) and [sup 16]O(e,e[prime]p[sub 0]), comparison of the [sup 12]C(e, e[prime]p[sub 0]) and [sup 16]O(e,e[prime]p[sub 3]) reactions, quadrupole strength in the [sup 16]O(e,e[prime][alpha][sub 0]) reaction, quadrupole strength in the [sup 12]C(e,e[prime][alpha]) reaction, analysis of the [sup 12]C(e,e[prime]p[sub 1]) and [sup 16]O(e,e[prime]p[sub 3]) angular distributions, analysis of the [sup 40]Ca(e,e[prime]x) reaction at low q, analysis of the higher-q [sup 12]C(e,e[prime]x) data from Bates), models of nuclear structure (experimental work, Hartree-Fock calculations, phonon excitations in spherical nuclei, shell model calculations, variational methods for relativistic fields), and instrumentation development efforts (developments at CEBAF, CLAS contracts, BLAST developments).

Not Available

1992-01-01T23:59:59.000Z

138

[Electromagnetic studies of nuclear structure and reactions]. Progress summary  

SciTech Connect

The experimental goals are focused on developing an understanding of strong interactions and the structure of hadronic systems by determination of the electromagnetic response; these goals will be accomplished through coincidence detection of final states. Nuclear modeling objectives are to organize and interpret the data through a consistent description of a broad spectrum of reaction observables; calculations are performed in a nonrelativistic diagrammatic framework as well as a relativistic QHD approach. Work is described according to the following arrangement: direct knockout reactions (completion of {sup 16}O(e,e{prime}p), {sup 12}C(e,e{prime}pp) progress, large acceptance detector physics simulations), giant resonance studies (intermediate-energy experiments with solid-state detectors, the third response function in {sup 12}C(e,e{prime}p{sub 0}) and {sup 16}O(e,e{prime}p{sub 0}), comparison of the {sup 12}C(e, e{prime}p{sub 0}) and {sup 16}O(e,e{prime}p{sub 3}) reactions, quadrupole strength in the {sup 16}O(e,e{prime}{alpha}{sub 0}) reaction, quadrupole strength in the {sup 12}C(e,e{prime}{alpha}) reaction, analysis of the {sup 12}C(e,e{prime}p{sub 1}) and {sup 16}O(e,e{prime}p{sub 3}) angular distributions, analysis of the {sup 40}Ca(e,e{prime}x) reaction at low q, analysis of the higher-q {sup 12}C(e,e{prime}x) data from Bates), models of nuclear structure (experimental work, Hartree-Fock calculations, phonon excitations in spherical nuclei, shell model calculations, variational methods for relativistic fields), and instrumentation development efforts (developments at CEBAF, CLAS contracts, BLAST developments).

Not Available

1992-12-31T23:59:59.000Z

139

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

E-Print Network (OSTI)

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

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

2013-06-10T23:59:59.000Z