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Physics Faculty Publications

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Articles 1621 - 1650 of 2178

Full-Text Articles in Physical Sciences and Mathematics

Cofe2o4 Nanostructures With High Coercivity, J S. Jung, J H. Lim, K H. Choi, S L. Oh, Y R. Kim, S H. Lee, D A. Smith, K L. Stokes, L Malkinski, C J. O'Connor Jan 2005

Cofe2o4 Nanostructures With High Coercivity, J S. Jung, J H. Lim, K H. Choi, S L. Oh, Y R. Kim, S H. Lee, D A. Smith, K L. Stokes, L Malkinski, C J. O'Connor

Physics Faculty Publications

Nanometer-sized ferrite magnetic materials are the subject of intense research interest due to their potential applications in high-density magnetic information storage. One of the most explored ferrite materials is the cobalt ferrite (CoFe2O4).. We have synthesized cobalt ferrite nanowires using cobalt ferrite nanoparticles in a porous anodic alumina template (AAT). The process of embedding ferrimagnetic particles into the pores was assisted by the magnetic field of a permanent magnet placed in vacuum directly under the substrate. Particles synthesized in the template were subsequently annealed at 600 °C for 2 h in Ar gas forming arrays of cobalt ferrite nanowires inside …

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Large Plasma-Edge Broadened Magneto-Optic-Polar-Kerr-Effect-Based Broadband Incoherent Detection Of Terahertz Spectral Frequencies, A. De, A. Puri Jan 2005

Large Plasma-Edge Broadened Magneto-Optic-Polar-Kerr-Effect-Based Broadband Incoherent Detection Of Terahertz Spectral Frequencies, A. De, A. Puri

Physics Faculty Publications

A magneto-optic Kerr effect (MOKE)-based spectroscopic technique is proposed in the terahertz regime. This method relies on very large reflection edge splitting effects, which occur when the cyclotron frequency (CF) is of the same order of magnitude or greater than the plasma frequency. In the event of a very large reflection edge split, the Kerr rotation (KR) no longer occurs at the plasma edge, but instead occurs at Re(ε+ε−) ≈ 1, within the macroscopic framework of the Drude model. This implies that one can control the spectral occurrence of the MOKE resonance, simply by tuning …

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Entropic Analysis Of Color Homogeneity, Kirill Alemaskin, Ica Manas Zloczower, Miron Kaufman Jan 2005

Entropic Analysis Of Color Homogeneity, Kirill Alemaskin, Ica Manas Zloczower, Miron Kaufman

Physics Faculty Publications

We propose an entropic measure to assess color homogeneity as well as deviations from a standard/ideal color. We illustrate the concept by analyzing samples obtained in a single screw extruder by mixing blue and yellow polymer pellets. Alternatively the proposed technique can be employed to assess the efficiency and degree of distributive mixing attained in polymer processing equipment.

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Medical Image Processing Using Transient Fourier Holography In Bacteriorhodopsin Films, Sri-Rajasekhar Kothapalli, Pengfei Wu, Chandra S. Yelleswarapu, D.V.G.L.N. Rao Dec 2004

Medical Image Processing Using Transient Fourier Holography In Bacteriorhodopsin Films, Sri-Rajasekhar Kothapalli, Pengfei Wu, Chandra S. Yelleswarapu, D.V.G.L.N. Rao

Physics Faculty Publications

Real time image processing is demonstrated by recording and reconstructing the transient photoisomerizative grating formed in the bR film using Fourier holography. Desired spatial frequencies including both high and low band in the object beam are reconstructed by controlling the reference beam intensity. The results are in agreement with a theoretical model based on photoisomerization grating. We exploit this technique to process mammograms in real-time for identification of microcalcifications buried in the soft tissue for early detection of breast cancer. A feature of the technique is the ability to transient display of selected spatial frequencies in the reconstructing process which …

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Laboratory Experiments Of Entrainment In Dry Convective Boundary Layers, Harm J.J. Jonker, Thijs Heus, Esther Hagen, Han Van Dop Dec 2004

Laboratory Experiments Of Entrainment In Dry Convective Boundary Layers, Harm J.J. Jonker, Thijs Heus, Esther Hagen, Han Van Dop

Physics Faculty Publications

Entrainment in dry convective boundary layers was studied. A saline convection tank set-up was used as a laboratory model for a dry convective atmospheric boundary layer. The entrainment flux was measured using planar laser induced fluorescence (PLIF). It was found that the entrainment flux reveals a much stronger dependence on the inversion strength than large eddy simulations tend to do.

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Theoretical Study Of The Magnetic Ordering In Rare-Earth Compounds With Face-Centered-Cubic Structure, Chun-Gang Duan, Renat F. Sabirianov, Jianjun Liu, Wai-Ning Mei, Peter A. Dowben, John R. Hardy Nov 2004

Theoretical Study Of The Magnetic Ordering In Rare-Earth Compounds With Face-Centered-Cubic Structure, Chun-Gang Duan, Renat F. Sabirianov, Jianjun Liu, Wai-Ning Mei, Peter A. Dowben, John R. Hardy

Physics Faculty Publications

We present a detailed theoretical study of the magnetic ordering in heavy rare-earth compounds with a face-centered-cubic structure. In addition to the exchange interactions which are counted up to the third nearest neighbors, the effect of the dipolar interactions and magnetic anisotropic effect are also included in our model Hamiltonian. The interactions parameters are obtained from first-principles band-structure calculations by fitting the total energies of different magnetic configurations to the Heisenberg Model. Thus from utilizing the Monte Carlo simulations, we explained the formation of different magnetic structures in the rare-earth compounds.

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Micro-Auger Electron Spectroscopy Studies Of Chemical And Electronic Effects At Gan-Sapphire Interfaces, X. L. Sun, S. T. Bradley, G. H. Jessen, David C. Look, Richard J. Molnar, L. J. Brillson Nov 2004

Micro-Auger Electron Spectroscopy Studies Of Chemical And Electronic Effects At Gan-Sapphire Interfaces, X. L. Sun, S. T. Bradley, G. H. Jessen, David C. Look, Richard J. Molnar, L. J. Brillson

Physics Faculty Publications

We have used cross-sectional micro-Auger electron spectroscopy (AES), coupled with micro-cathodoluminescence (CLS) spectroscopy, in a UHV scanning electron microscope to probe the chemical and related electronic features of hydride vapor phase epitaxy GaN/sapphire interfaces on a nanometer scale. AES images reveal dramatic evidence for micron-scale diffusion of O from Al2O3 into GaN. Conversely, plateau concentrations of N can extend microns into the sapphire, corresponding spatially to a 3.8 eV defect emission and Auger chemical shifts attributed to Al-N-O complexes. Interface Al Auger signals extending into GaN indicates AlGaN alloy formation, consistent with a blue-shifted CLS local interface …

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As-Doped P-Type Zno Produced By An Evaporation/Sputtering Process, David C. Look, G. M. Renlund, R. H. Burgener, J. R. Sizelove Nov 2004

As-Doped P-Type Zno Produced By An Evaporation/Sputtering Process, David C. Look, G. M. Renlund, R. H. Burgener, J. R. Sizelove

Physics Faculty Publications

Strongly p-type ZnO is produced by the following sequence of steps: (1) evaporation of Zn3As2 on a fused-quartz substrate at 350 °C; and (2) sputtering of ZnO with substrate held at 450 °C. The electrical characteristics include: resistivity of 0.4 Ω cm, a mobility of 4 cm2∕V s, and a hole concentration of about 4×1018 cm−3. This resistivity is among the best (lowest) ever reported for p-type ZnO. Secondary-ion mass spectroscopic analysis gives an average As concentration about 5×1019 cm−3, and a simple one-band fit of the …

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Response Of The Martian Thermosphere/Ionosphere To Enhanced Fluxes Of Solar Soft X Rays, Jane L. Fox Oct 2004

Response Of The Martian Thermosphere/Ionosphere To Enhanced Fluxes Of Solar Soft X Rays, Jane L. Fox

Physics Faculty Publications

We have investigated the response of the thermosphere and ionosphere of Mars to enhanced fluxes of solar soft X rays, such as those that have been detected by the SNOE satellite (e.g., Bailey et al., 2000 ). We have constructed standard models by adopting the SC#21REFW and F79050N solar fluxes from H. E. Hinteregger (private communication) (see also Torr et al., 1979 ) for the low and high solar activity models, respectively. We then constructed enhanced soft X-ray models by multiplying the solar photon fluxes for wavelengths below 200 Å by a factor of 3 at low solar …

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Below Band Gap Photoreflectance Transitions In Epitaxial Gan, Phil W. Yu, Jerry D. Clark, David C. Look, C. Q. Chen, Jinwei Yang, Edmundas Koutstis, M. Asif Khan, Denis V. Tsvertkov, Vladimir A. Dmitriev Sep 2004

Below Band Gap Photoreflectance Transitions In Epitaxial Gan, Phil W. Yu, Jerry D. Clark, David C. Look, C. Q. Chen, Jinwei Yang, Edmundas Koutstis, M. Asif Khan, Denis V. Tsvertkov, Vladimir A. Dmitriev

Physics Faculty Publications

A photoreflectance (PR) and photoluminescence (PL) study has been performed on a Si-doped epitaxial GaN layer that contains impurity or defect related below band gap features in its PR spectrum. In the 300 K PR spectrum, these features appear at energies of 3.26 and 3.33 eV, respectively, but below 180 K they can no longer be seen. The 3.26 eV line evidently corresponds to a donor acceptor pair transition, also seen in PL. The origin of the 3.33 eV line is uncertain, but may correspond to a transition involving the nitrogen vacancy.

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Co2+ Dissociative Recombination: A Source Of Thermal And Nonthermal C On Mars, Jane L. Fox Aug 2004

Co2+ Dissociative Recombination: A Source Of Thermal And Nonthermal C On Mars, Jane L. Fox

Physics Faculty Publications

CO2 + dissociative recombination has been assumed in the past to proceed overwhelmingly by the channel that produces CO + O. Although the channel that leads to the products C + O2 is energetically possible, the significant rearrangement of bonds that is required has led to the belief that this channel contributes minimally. Seiersen et al. [2003] have recently measured the branching ratio for the latter channel, and they have reported a value of ∼9% of the total. We have constructed both low and high solar activity models of the Martian thermosphere, and we have tested the effect …

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Hot Carbon Densities In The Exosphere Of Venus, Michael W. Liemohn, Jane L. Fox, Andrew F. Nagy, Xiaohua Fang Aug 2004

Hot Carbon Densities In The Exosphere Of Venus, Michael W. Liemohn, Jane L. Fox, Andrew F. Nagy, Xiaohua Fang

Physics Faculty Publications

The results of calculations of hot carbon densities in the exosphere of Venus are presented. The calculation is a two-step process. First a two-stream transport code is used to solve for the distribution function at the exobase, and then these results are used in a Liouville equation solution above the exobase. It is found that generally, photodissociation of carbon monoxide is the largest source of hot carbon atoms in the upper atmosphere of Venus, larger than dissociative recombination of CO+ and significantly larger than the creation of hot carbon through collisions with hot oxygen atoms. It is also found …

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L10 Ordered Fept:C Composite Films With (001) Texture, M. L. Yan, Renat F. Sabirianov, Y. F. Xu, X Z. Li, David J. Sellmyer Jul 2004

L10 Ordered Fept:C Composite Films With (001) Texture, M. L. Yan, Renat F. Sabirianov, Y. F. Xu, X Z. Li, David J. Sellmyer

Physics Faculty Publications

Highly textured (001) FePt:C nanocomposite thin films, deposited directly on thermally oxidized Si wafers, are obtained by multilayer deposition plus subsequent thermal annealing. Nanostructures, crystalline orientations, interactions, and magnetic properties are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), magnetic force microscopy, and magnetic measurements. The formation of the ordered L10 phase is confirmed by XRD, and only visible (00 ) peaks indicate a high degree of the (001) texture. TEM observation reveals that FePt grains are embedded in the C matrix and appear to be well isolated.

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Simulations Of Ferroelectric Polymer Film Polarization: The Role Of Dipole Interactions, Chun-Gang Duan, Wai-Ning Mei, Jianjun Liu, John R. Hardy, Stephen Ducharme, Peter A. Dowben Jun 2004

Simulations Of Ferroelectric Polymer Film Polarization: The Role Of Dipole Interactions, Chun-Gang Duan, Wai-Ning Mei, Jianjun Liu, John R. Hardy, Stephen Ducharme, Peter A. Dowben

Physics Faculty Publications

We present a systematic study of the dipole alignment in the polyvinylidene fluoride (PVDF) films using first-principles total energy calculations. The ground state of a single layer film is a state with all the dipoles lying parallel to the film plane. This can also be explained by a dipole-dipole interaction model. The induced mirror charges on conducting substrates or substrates with a non-negligible dielectric response play an important role in aligning the polarization perpendicular to the film. From fitting the ab initio calculations, we obtain an effective monomer dipole moment of 4.7 x 10−30 C m. This corresponds to …

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Anomalous Capture And Emission From Internal Surfaces Of Semiconductor Voids: Nanopores In Sic, David C. Look, Z-Q. Fang, S. Soloviev, T. S. Sudarshan, J. J. Boeckl May 2004

Anomalous Capture And Emission From Internal Surfaces Of Semiconductor Voids: Nanopores In Sic, David C. Look, Z-Q. Fang, S. Soloviev, T. S. Sudarshan, J. J. Boeckl

Physics Faculty Publications

Deep level transient spectroscopy in nanoporous, n-type SiC reveals a new type of deep (˜0.8 eV) trap that can hold more than 100 electrons and that has anomalous capture and emission behavior. Here we quantitatively explain these effects with a new, general formalism that treats both emission and capture in the presence of dynamic energy barriers, resulting from the charging and discharging of states on the internal surfaces of voids, such as pores or nanopipes. The capture kinetics display a logarithmic time dependence over a certain filling range, as has often been observed in connection with dislocation-related trapping.

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Reduced Threshold Current Of A Quantum Dot Laser In A Short Period Superlattice Of Indirect-Band Gap, Greg Sun, Richard A. Soref, Jacob B. Khurgin Apr 2004

Reduced Threshold Current Of A Quantum Dot Laser In A Short Period Superlattice Of Indirect-Band Gap, Greg Sun, Richard A. Soref, Jacob B. Khurgin

Physics Faculty Publications

We propose the idea of making quantum dot lasers by embedding direct-band gap quantum dots in a short period superlattice whose band gap is indirect. This technique reduces the threshold current and its temperature dependence. We show that a higher characteristic-temperature T0 can be achieved in a quantum dot laser with indirect GaAs/AlAs superlattice barriers compared to that with direct GaAs barriers.

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Calculation Of The Radiation Trapping Force For Laser Tweezers By Use Of Generalized Lorenz-Mie Theory. I. Localized Model Description Of An On-Axis Tightly Focused Laser Beam With Spherical Aberration, James A. Lock Apr 2004

Calculation Of The Radiation Trapping Force For Laser Tweezers By Use Of Generalized Lorenz-Mie Theory. I. Localized Model Description Of An On-Axis Tightly Focused Laser Beam With Spherical Aberration, James A. Lock

Physics Faculty Publications

Calculation of the radiation trapping force in laser tweezers by use of generalized Lorenz-Mie theory requires knowledge of the shape coefficients of the incident laser beam. The localized version of these coefficients has been developed and justified only for a moderately focused Gaussian beam polarized in the x direction and traveling in the positive z direction. Here the localized model is extended to a beam tightly focused and truncated by a high-numerical-aperture lens, aberrated by its transmission through the wall of the sample cell, and incident upon a spherical particle whose center is on the beam axis. We also consider …

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Calculation Of The Radiation Trapping Force For Laser Tweezers By Use Of Generalized Lorenz-Mie Theory. Ii. On-Axis Trapping Force, James A. Lock Apr 2004

Calculation Of The Radiation Trapping Force For Laser Tweezers By Use Of Generalized Lorenz-Mie Theory. Ii. On-Axis Trapping Force, James A. Lock

Physics Faculty Publications

The efficiency of trapping an on-axis spherical particle by use of laser tweezers for a particle size from the Rayleigh limit to the ray optics limit is calculated from generalized Lorenz-Mie light-scattering theory and the localized version of a Gaussian beam that has been truncated and focused by a high-numericalaperture lens and that possesses spherical aberration as a result of its transmission through the wall of the sample cell. The results are compared with both the experimental trapping efficiency and the theoretical efficiency obtained from use of the localized version of a freely propagating focused Gaussian beam. The predicted trapping …

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Remote Hydrogen Plasma Doping Of Single Crystal Zno, Yuri M. Strzhemechny, Howard L. Mosbacker, David C. Look, Donald C. Reynolds, Cole W. Litton, Nelson Y. Garces, Nancy C. Giles, Larry E. Halliburton, Shigeru Niki, Leonard J. Brillson Apr 2004

Remote Hydrogen Plasma Doping Of Single Crystal Zno, Yuri M. Strzhemechny, Howard L. Mosbacker, David C. Look, Donald C. Reynolds, Cole W. Litton, Nelson Y. Garces, Nancy C. Giles, Larry E. Halliburton, Shigeru Niki, Leonard J. Brillson

Physics Faculty Publications

We demonstrate that remote plasma hydrogenation can increase electron concentrations in ZnO single crystals by more than an order of magnitude. We investigated the effects of this treatment on Hall concentration and mobility as well as on the bound exciton emission peak I4 for a variety of ZnO single crystals–bulk air annealed, Li doped, and epitaxially grown on sapphire. Hydrogen increases I4 intensity in conducting samples annealed at 500 and 600 °C and partially restores emission in the I4 range for Li-diffused ZnO. Hydrogenation increases carrier concentration significantly for the semi-insulating Li doped and epitaxial thin film …

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Reply To "Comment On 'Recombination Of Excitons Bound To Oxygen And Silicon Donors In Freestanding Gan' ", A. Wysmolek, K. P. Korona, R. Stepniewski, J. M. Baranowsky, J. Bloniarz, M. Potemski, R. L. Jones, David C. Look, J. Kuhl, Seong-Ju S. Park, S. K. Lee Apr 2004

Reply To "Comment On 'Recombination Of Excitons Bound To Oxygen And Silicon Donors In Freestanding Gan' ", A. Wysmolek, K. P. Korona, R. Stepniewski, J. M. Baranowsky, J. Bloniarz, M. Potemski, R. L. Jones, David C. Look, J. Kuhl, Seong-Ju S. Park, S. K. Lee

Physics Faculty Publications

In their Comment on our publication [Phys. Rev. B 66, 245317 (2002)], Freitas et al. criticize our identification of donor-bound exciton transitions and the analysis of two-electron satellite emission lines. We show that some arguments given in the Comment are in conflict with our time-resolved and magneto-optical data. We present a discussion of the intradonor transition energies and donor chemical shifts to avoid misunderstanding.

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Spectral Dependence Of Coherent Backscattering Of Light In A Narrow-Resonance Atomic System, D. V. Kupriyanov, I. M. Sokolov, N. V. Larionov, P. Kulatunga, C. I. Sukenik, S. Balik, M. D. Havey Mar 2004

Spectral Dependence Of Coherent Backscattering Of Light In A Narrow-Resonance Atomic System, D. V. Kupriyanov, I. M. Sokolov, N. V. Larionov, P. Kulatunga, C. I. Sukenik, S. Balik, M. D. Havey

Physics Faculty Publications

We report a combined theoretical and experimental study of the spectral and polarization dependence of near-resonant radiation coherently backscattered from an ultracold gas of 85Rb atoms. Measurements in a 6 MHz range about the 5s 2S1/25p 2P3/2, F=3F'=4 hyperfine transition are compared with simulations based on a realistic model of the experimental atomic density distribution. In the simulations, the influence of heating of the atoms in the vapor, magnetization of the vapor, finite spectral bandwidth, and other nonresonant hyperfine transitions are considered. Good agreement is found between the simulations and measurements.

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High-Quality, Melt-Grown Zno Single Crystals, D. C. Reynolds, C. W. Litton, David C. Look, J. E. Joelscher, B. Claflin, T. C. Collins, J. Nause, B. Nemeth Feb 2004

High-Quality, Melt-Grown Zno Single Crystals, D. C. Reynolds, C. W. Litton, David C. Look, J. E. Joelscher, B. Claflin, T. C. Collins, J. Nause, B. Nemeth

Physics Faculty Publications

High-quality, melt-grown ZnO crystals are reported. The reflection and emission spectra of the melt-grown samples are compared with the same spectra from high-quality, vapor-grown ZnO crystals. We isolate the reflection and emission spectra predominantly related to the intrinsic properties associated with the wurtzite structure of the crystals. The quality of the crystals is reflected in the spectral reproduction of the intrinsic properties of the crystals. Both the ground state and the n=2 state of the free excitons associated with the A, B, and C valence bands of the crystals are spectrally observed in reflection. Assuming a hydrogenic character for …

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Age Differences In Central (Semantic) And Peripheral Processing: The Importance Of Considering Both Response Times And Errors, Philip A. Allen, Martin D. Murphy, Miron Kaufman, Karen E. Groth, Ana Begovic Jan 2004

Age Differences In Central (Semantic) And Peripheral Processing: The Importance Of Considering Both Response Times And Errors, Philip A. Allen, Martin D. Murphy, Miron Kaufman, Karen E. Groth, Ana Begovic

Physics Faculty Publications

In this project we examined the effect of adult age on visual word recognition by using combined reaction time (RT) and accuracy methods based on the Hick–Hyman law. This was necessary because separate Brinley analyses of RT and errors resulted in contradicting results. We report the results of a lexical decision task experiment (with 96 younger adults and 97 older adults). We transformed the error data into entropy and then predicted RT by using entropy values separately for exposure duration (thought to influence peripheral processes) and word frequency (thought to influence central processes). For exposure duration, the entropy–RT functions indicate …

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Variable-Temperature Scanning Optical And Force Microscope, Petru S. Fodor, H. Zhu, N. G. Patil, J. Levy Jan 2004

Variable-Temperature Scanning Optical And Force Microscope, Petru S. Fodor, H. Zhu, N. G. Patil, J. Levy

Physics Faculty Publications

The implementation of a scanning microscope capable of working in confocal, atomic force and apertureless near field configurations is presented. The microscope is designed to operate in the temperature range 4–300 K, using conventional helium flow cryostats. In atomic force microscope(AFM) mode, the distance between the sample and an etchedtungsten tip is controlled by a self-sensing piezoelectrictuning fork. The vertical position of both the AFM head and microscope objective can be accurately controlled using piezoelectric coarse approach motors. The scanning is performed using a compact XYZ stage, while the AFM and optical head are kept fixed, allowing scanning probe and …

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Scattering Of Shock Waves In Qcd, Ian Balitsky Jan 2004

Scattering Of Shock Waves In Qcd, Ian Balitsky

Physics Faculty Publications

The cross section of heavy-ion collisions is represented as a double functional integral with the saddle point being the classical solution of the Yang-Mills equations with boundary conditions/sources in the form of two shock waves corresponding to the two colliding ions. I develop the expansion of this classical solution in powers of the commutator of the Wilson lines describing the colliding particles and calculate the first two terms of the expansion.

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Inclusive Photoproduction Of Lepton Pairs In The Parton Model, A. Psaker Jan 2004

Inclusive Photoproduction Of Lepton Pairs In The Parton Model, A. Psaker

Physics Faculty Publications

In the framework of the QCD parton model, we study unpolarized scattering of high energy real photons from a proton target into lepton pairs and a system of hadrons. For a given parametrization of parton distributions in the proton, we calculate the cross section of this process and show the cancellation of the interference terms.

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Complete Angular Distribution Measurements Of Two-Body Deuteron Photodisintegration Between 0.5 And 3 Gev, H. Bagdasaryan, H. Bektasoglu, G. E. Dodge, T. A. Forest, C. E. Hyde-Wright, A. Klein, A. V. Klimenko, S. E. Kuhn, F. Sabatié, S. Stepanyan, L. B. Weinstein, J. Yun, Et Al., The Clas Collaboration Jan 2004

Complete Angular Distribution Measurements Of Two-Body Deuteron Photodisintegration Between 0.5 And 3 Gev, H. Bagdasaryan, H. Bektasoglu, G. E. Dodge, T. A. Forest, C. E. Hyde-Wright, A. Klein, A. V. Klimenko, S. E. Kuhn, F. Sabatié, S. Stepanyan, L. B. Weinstein, J. Yun, Et Al., The Clas Collaboration

Physics Faculty Publications

Nearly complete angular distributions of the two-body deuteron photodisintegration differential cross section have been measured using the CEBAF Large Acceptance Spectrometer detector and the tagged photon beam at the Thomas Jefferson National Accelerator Facility. The data cover photon energies between 0.5 and 3.0 GeV and center-of-mass proton scattering angles 10°–160°. The data show a persistent forward-backward angle asymmetry over the explored energy range, and are well described by the nonperturbative quark gluon string model.

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Complete Measurement Of Three-Body Photodisintegration Of 3He For Photon Energies Between 0.35 And 1.55 Gev, H. Bagdasaryan, M. Bektasoglu, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, G. Gavalian, N. Guler, C. E. Hyde-Wright, A. Klein, S. E. Kuhn, L. M. Qin, S. Stepanyan, L. B. Weinstein, J. Yun, Et Al., The Clas Collaboration Jan 2004

Complete Measurement Of Three-Body Photodisintegration Of 3He For Photon Energies Between 0.35 And 1.55 Gev, H. Bagdasaryan, M. Bektasoglu, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, G. Gavalian, N. Guler, C. E. Hyde-Wright, A. Klein, S. E. Kuhn, L. M. Qin, S. Stepanyan, L. B. Weinstein, J. Yun, Et Al., The Clas Collaboration

Physics Faculty Publications

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.

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Experimental Determination Of The Evolution Of The Bjorken Integral At Low Q², A. Deur, P. Bosted, V. Burkert, G. Cates, J.P. Chen, Seonho Choi, D. Crabb, C.W. De Jager, R. De Vita, G.E. Dodge, R. Fatemi, T.A. Forest, F. Garibaldi, R. Gilman, E. W. Hughes, X. Jiang, W. Korsch, S. E. Kuhn, W. Melnitchouk, Z.-E. Meziani, R. Minehart, A.V. Skabelin, K. Slifer, M. Taiuti, J. Yun Jan 2004

Experimental Determination Of The Evolution Of The Bjorken Integral At Low Q², A. Deur, P. Bosted, V. Burkert, G. Cates, J.P. Chen, Seonho Choi, D. Crabb, C.W. De Jager, R. De Vita, G.E. Dodge, R. Fatemi, T.A. Forest, F. Garibaldi, R. Gilman, E. W. Hughes, X. Jiang, W. Korsch, S. E. Kuhn, W. Melnitchouk, Z.-E. Meziani, R. Minehart, A.V. Skabelin, K. Slifer, M. Taiuti, J. Yun

Physics Faculty Publications

We extract the Bjorken integral 𝚪1p-n in the range 0.17 < Q2 <1.10 GeV2 from inclusive scattering of polarized electrons by polarized protons, deuterons, and 3He, for the region in which the integral is dominated by nucleon resonances. These data bridge the domains of the hadronic and partonic descriptions of the nucleon. In combination with earlier measurements at higher Q2, we extract the nonsinglet twist-4 matrix element f2.

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Hyperon Photoproduction In The Nucleon Resonance Region, K. V. Dharmawardane, G. E. Dodge, C. E. Hyde-Wright, S. E. Kuhn, L. M. Qin, L. B. Weinstein, J. Yun, Et Al., Clas Collaboration Jan 2004

Hyperon Photoproduction In The Nucleon Resonance Region, K. V. Dharmawardane, G. E. Dodge, C. E. Hyde-Wright, S. E. Kuhn, L. M. Qin, L. B. Weinstein, J. Yun, Et Al., Clas Collaboration

Physics Faculty Publications

High-statistics cross sections and recoil polarizations for the reactions γ+p → K++ Λ and γ+p→K++ Σ0 have been measured at CLAS for center-of-mass energies between 1.6 and 2.3 GeV. In the K+Λ channel we confirm a resonance-like structure near W = 1.9 GeV at backward kaon angles. Our data show more complex s- and u- channel behavior than previously seen, since structure is also present at forward angles, but not at central angles. The position and width change with angle, indicating that more than one resonance is playing a role. Large positive Λ polarization at …

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