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Articles 31 - 52 of 52
Full-Text Articles in Physical Sciences and Mathematics
Quantitative Method For Measurement Of The Goos-Hanchen Effect Based On Source Divergence Considerations, Jeffrey F. Gray, Ashok Puri
Quantitative Method For Measurement Of The Goos-Hanchen Effect Based On Source Divergence Considerations, Jeffrey F. Gray, Ashok Puri
Physics Faculty Publications
In this paper we report on a method for quantitative measurement and characterization of the Goos-Hanchen effect based upon the real world performance of optical sources. A numerical model of a nonideal plane wave is developed in terms of uniform divergence properties. This model is applied to the Goos-Hanchen shift equations to determine beam shift displacement characteristics, which provides quantitative estimates of finite shifts near critical angle. As a potential technique for carrying out a meaningful comparison with experiments, a classical method of edge detection is discussed. To this end a line spread Green’s function is defined which can be …
Dynamic And Temperature Effects In Toggle Magnetic Random Access Memory, Dorin Cimpoesu, Alexandru Stancu, Leonard Spinu
Dynamic And Temperature Effects In Toggle Magnetic Random Access Memory, Dorin Cimpoesu, Alexandru Stancu, Leonard Spinu
Physics Faculty Publications
In this paper we have studied the dynamic switching in magnetic random access memory (MRAM) and its dependence on thermal effects due to a finite temperature. The model is based on the Landau-Lifshitz-Gilbert equation and the stochastic Landau-Lifshitz-Gilbert equation which are numerically integrated. The magnetic layers are assumed to be ellipsoid shaped with each magnetic layer single domain. In addition, we have taken into account the uniaxial intrinsic anisotropy. Simulations were performed for both balanced and nonbalanced synthetic antiferromagnetic elements. The switching properties are discussed as a function of applied field pulses’ length and shape. In this paper we present …
Physics Of Complex Transverse Susceptibility Of Magnetic Particulate Systems, Dorin Cimpoesu, Alexandru Stancu, Leonard Spinu
Physics Of Complex Transverse Susceptibility Of Magnetic Particulate Systems, Dorin Cimpoesu, Alexandru Stancu, Leonard Spinu
Physics Faculty Publications
Complex transverse susceptibility is a recent proposed method for the determination of anisotropy and volume distributions in particulate magnetic media. So far, only thermal fluctuations and rate-dependent damped dynamics of the magnetic moment have been identified as reasons for the existence of the imaginary transverse susceptibility. In this paper, we apply a more general approach to derive the complex transverse susceptibility, and we show that the hysteresis phenomenon is the most general concept behind the existence of complex transverse susceptibility. In this paper, the physical origins of the imaginary part of transverse susceptibility are analyzed: rate-independent hysteresis, viscous-type rate-dependent hysteresis, …
Revisiting Hafemeister’S ‘Science And Society’ Tests, Robert J. Brecha, Rex L. Berney, Bruce A. Craver
Revisiting Hafemeister’S ‘Science And Society’ Tests, Robert J. Brecha, Rex L. Berney, Bruce A. Craver
Physics Faculty Publications
We revisit a series of papers on science and society issues by David Hafemeister in the 1970s and 1980s. The emphasis in the present work is on world oil production limits and some consequences of various possible scenarios for the near future. Some of the data and scenarios used by Hafemeister are updated for U.S. oil production in the past two decades and extended to an analysis of a peak in world oil production in the future. We discuss some simple scenarios for future energy use patterns and look at the consequence of these scenarios as world oil production begins …
Ionization In Fast Atom-Atom Collisions: The Influence And Scaling Behavior Of Electron-Electron And Electron-Nucleus Interactions, J. M. Sanders, R. D. Dubois, S. T. Manson, S. Datz, Edward Deveney, H. F. Krause, J. L. Shinpaugh, C. R. Vane
Ionization In Fast Atom-Atom Collisions: The Influence And Scaling Behavior Of Electron-Electron And Electron-Nucleus Interactions, J. M. Sanders, R. D. Dubois, S. T. Manson, S. Datz, Edward Deveney, H. F. Krause, J. L. Shinpaugh, C. R. Vane
Physics Faculty Publications
We report cross sections for ionization of He coincident with electron loss from He, Li, C, O, and Ne projectiles. For He, Li, C, and O projectiles, the cross sections were measured directly, while the Ne cross sections were obtained by transforming results for He projectiles colliding with Ne. We find that, at energies of about 100–500 keV/u, neutral projectiles can ionize a He target almost as effectively as a charged projectile. The contribution to ionization due to electron-electron interactions is found to scale with the number of available projectile electrons. Comparing ionization by the bound electrons on projectiles to …
Temperature Dependence Of Terahertz Emission From Inmnas, Hui Zhan, Jason A. Deibel, Jonathan Laib, Chanjuan Sun, Junichiro Kono, Daniel M. Mittleman, Hiro Munekata
Temperature Dependence Of Terahertz Emission From Inmnas, Hui Zhan, Jason A. Deibel, Jonathan Laib, Chanjuan Sun, Junichiro Kono, Daniel M. Mittleman, Hiro Munekata
Physics Faculty Publications
No abstract provided.
Students’ Use Of Symmetry With Gauss’S Law, Adrienne L. Traxler, Katrina E. Black, John R. Thompson
Students’ Use Of Symmetry With Gauss’S Law, Adrienne L. Traxler, Katrina E. Black, John R. Thompson
Physics Faculty Publications
To study introductory student difficulties with electrostatics, we compared student techniques when finding the electric field for spherically symmetric and non-spherically symmetric charged conductors. We used short interviews to design a free-response and multiple-choice-multiple-response survey that was administered to students in introductory calculus-based courses. We present the survey results and discuss them in light of Singh's results for Gauss's Law, Collins and Ferguson's epistemic forms and games, and Tuminaro's extension of games and frames.
Electron And Hole Traps In N-Doped Zno Grown On P-Type Si Substrate By Mocvd, Zhaoqiang Fang, Bruce B. Claflin, David C. Look, Lei L. Kerr, Xiaonan Li
Electron And Hole Traps In N-Doped Zno Grown On P-Type Si Substrate By Mocvd, Zhaoqiang Fang, Bruce B. Claflin, David C. Look, Lei L. Kerr, Xiaonan Li
Physics Faculty Publications
Electron and hole traps in N-doped ZnO were investigated using a structure of n+-ZnO:Al/i-ZnO/ZnO:N grown on a p-Si substrate by metalorganic chemical vapor deposition (for growth of the ZnO:N layer) and sputtering deposition (for growth of the i-ZnO and n+-ZnO:Al layers). Current-voltage and capacitance-voltage characteristics measured at temperatures from 200 to 400 K show that the structure is an abrupt n+−p diode with very low leakage currents. By using deep level transient spectroscopy, two hole traps, H3 (0.35 eV) and H4 (0.48 eV), are found in the p-Si …
The Metal-Insulator Transition In Vo2 Studied Using Terahertz Apertureless Near-Field Microscopy, Hui Zhan, Victoria Astley, Michael Hvasta, Jason A. Deibel, Daniel M. Mittleman, Yong-Sik Lim
The Metal-Insulator Transition In Vo2 Studied Using Terahertz Apertureless Near-Field Microscopy, Hui Zhan, Victoria Astley, Michael Hvasta, Jason A. Deibel, Daniel M. Mittleman, Yong-Sik Lim
Physics Faculty Publications
We have studied the metal-insulator transition in a vanadium dioxide (VO2) thin film using terahertz apertureless near-field optical microscopy. We observe a variation of the terahertz amplitude due to the phase transition induced by an applied voltage across the sample. The change of the terahertz signal is related to the abrupt change of the conductivity of the VO2 film at the metal-insulator transition. The subwavelength spatial resolution of this near-field microscopy makes it possible to detect signatures of micron-scale metallic domains in inhomogeneous VO2 thin films.
Erratum: Cross Sections For The 𝛾p -> K*⁰ Σ⁺ Reaction At E𝛾 = 1.7-3.0 Gev (Physical Review C. 75, 042201), M. Amarian, H. Bagdasaryan, S. Bültmann, G. E. Dodge, G. Gavalian, C. E. Hyde-Wright, A. Klein, S. E. Kuhn, F. Sabatié, L. B. Weinstein, Et. Al., The Clas Collaboration
Erratum: Cross Sections For The 𝛾p -> K*⁰ Σ⁺ Reaction At E𝛾 = 1.7-3.0 Gev (Physical Review C. 75, 042201), M. Amarian, H. Bagdasaryan, S. Bültmann, G. E. Dodge, G. Gavalian, C. E. Hyde-Wright, A. Klein, S. E. Kuhn, F. Sabatié, L. B. Weinstein, Et. Al., The Clas Collaboration
Physics Faculty Publications
No abstract provided.
Quark Contribution To The Small-𝔁 Evolution Of Color Dipole, Ian Balitsky
Quark Contribution To The Small-𝔁 Evolution Of Color Dipole, Ian Balitsky
Physics Faculty Publications
The small-𝔁 deep inelastic scattering in the saturation region is governed by the nonlinear evolution of Wilson-lines operators. In the leading logarithmic approximation it is given by the Balitsky-Kovchegov (BK) equation for the evolution of color dipoles. In the next-to-leading order (NLO) the nonlinear equation gets contributions from quark and gluon loops. In this paper I calculate the quark-loop contribution to small-𝔁 evolution of Wilson lines in the NLO. It turns out that there are no new operators at the one-loop level—just as at the tree level, the high-energy scattering can be described in terms of Wilson lines. In addition, …
Low And Medium Β Superconducting Cavities And Accelerators, Jean R. Delayen
Low And Medium Β Superconducting Cavities And Accelerators, Jean R. Delayen
Physics Faculty Publications
No abstract provided.
Reactive Oxygen Emission From Microwave Discharge Plasmas, S. Popovic, M. Rašković, S. P. Kuo, L. Vuskovic
Reactive Oxygen Emission From Microwave Discharge Plasmas, S. Popovic, M. Rašković, S. P. Kuo, L. Vuskovic
Physics Faculty Publications
Metastable oxygen atoms and molecules have received increased interest because of their function in surface modification, bio-decontamination and many other industrial applications, in addition to the role in the upper atmospheric layer chemistry. We review work on production and detection of metastable oxygen and we describe our experiments, including the development of techniques for measurement of metastable molecular oxygen. We show that either metastable oxygen molecules or metastable oxygen atoms can be produced in large quantities in electrical discharges, carefully tailored to promote the required kinetics. Although the two species may coexist, colder discharge regimes favor production of molecules, while …
Quark-Hadron Duality In Spin Structure Functions G(1)(P) And G(1)(D), P. E. Bosted, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, S. E. Kuhn, Y. Prok, G. Adams, M. Amarian, P. Ambrozewicz, M. Anghinolfi, H. Bagdasaryan, M. Bektasoglu, S. Bültmann, S. L. Careccia, G. Gavalian, N. Guler, C. E. Hyde-Wright, H. G. Juengst, A. Klein, J. Lachniet, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, J. Zhang
Quark-Hadron Duality In Spin Structure Functions G(1)(P) And G(1)(D), P. E. Bosted, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, S. E. Kuhn, Y. Prok, G. Adams, M. Amarian, P. Ambrozewicz, M. Anghinolfi, H. Bagdasaryan, M. Bektasoglu, S. Bültmann, S. L. Careccia, G. Gavalian, N. Guler, C. E. Hyde-Wright, H. G. Juengst, A. Klein, J. Lachniet, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, J. Zhang
Physics Faculty Publications
New measurements of the spin structure functions of the proton and deuteron g(1)(p)(x,Q2) and g(1)(d)(x,Q2) in the nucleon resonance region are compared with extrapolations of target-mass-corrected next-to-leading-order (NLO) QCD fits to higher energy data. Averaged over the entire resonance region (W <2 >GeV), the data and QCD fits are in good agreement in both magnitude and Q2 dependence for Q2 >1.7 GeV2/c2. This "global" duality appears to result from cancellations among the prominent "local" resonance regions: in particular strong σ …
Form Factors And Wave Functions Of Vector Mesons In Holographic Qcd, Hovhannes R. Grigoryan, Anatoly V. Radyushkin
Form Factors And Wave Functions Of Vector Mesons In Holographic Qcd, Hovhannes R. Grigoryan, Anatoly V. Radyushkin
Physics Faculty Publications
Within the framework of a holographic dual model of QCD, we develop a formalism for calculating form factors of vector mesons. We show that the holographic bound states can be described not only in terms of eigenfunctions of the equation of motion, but also in terms of conjugate wave functions that are close analogues of quantum-mechanical bound state wave functions. We derive a generalized VMD representation for form factors, and find a very specific VMD pattern, in which form factors are essentially given by contributions due to the first two bound states in the Q2 -channel. We calculate electric …
Plasma Treatment Of Bulk Nb Surface In The Ar/Cl2 Discharge, M. Rašković, L. Vuskovic, S. Popovic, A.-M. Valente-Feliciano, L. Phillips
Plasma Treatment Of Bulk Nb Surface In The Ar/Cl2 Discharge, M. Rašković, L. Vuskovic, S. Popovic, A.-M. Valente-Feliciano, L. Phillips
Physics Faculty Publications
The preparation of the cavity walls has been one of the major challenges in the superconducting radio-frequency (SRF) accelerator technology. Therefore, constant research and development effort is devoted to develop surface preparation processes that will improve roughness and lower the level of impurities, like hydrogen or oxygen, embedded in bulk Nb, having in the same time reasonable etching rates. Plasma based surface modification provides an excellent opportunity to achieve these goals. We present Ar/Cl2 discharge treatment of bulk Nb where we achieved etching rates comparable to the rates obtained with the electropolishing method without introducing impurities in Nb. The …
Cascade Production In The Reactions 𝛾p → K⁺ K⁺(X) And 𝛾p → K⁺K⁺ Π⁻⁻(X), M. J. Amaryan, H. Bagdasaryan, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde-Wright, N. Kalantarians, A. Klein, S. E. Kuhn, M. R. Niroula, S. Tkachenko, L. B. Weinstein, J. Zhang, Et Al., Clas Collaboration
Cascade Production In The Reactions 𝛾p → K⁺ K⁺(X) And 𝛾p → K⁺K⁺ Π⁻⁻(X), M. J. Amaryan, H. Bagdasaryan, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde-Wright, N. Kalantarians, A. Klein, S. E. Kuhn, M. R. Niroula, S. Tkachenko, L. B. Weinstein, J. Zhang, Et Al., Clas Collaboration
Physics Faculty Publications
Photoproduction of the cascade resonances has been investigated in the reactions γp → K + K +(X) and γp → K + K + π −(X). The mass splitting of the ground state (Ξ−,Ξ0) doublet is measured to be 5.4 ± 1.8 MeV/c2, consistent with existing measurements. The differential (total) cross sections for the Ξ− have been determined for photon beam energies from 2.75 to 3.85 (4.75) GeV and are consistent with a production mechanism of Y∗→K+Ξ− through a t-channel process. The reaction γp→K+K+π−[Ξ0] has also been investigated to …
Experimental Study Of Exclusive ²H(E,E'P)N Reaction Mechanisms At High Q², S. E. Kuhn, M. J. Amaryan, H. Bagdasaryan, M. Bektasoglu, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, N. Guler, C. E. Hyde-Wright, H. G. Juengst, N. Kalantarians, A. Klein, M. R. Niroula, R. A. Niyazov, S. Tkachenko, L. B. Weinstein, J. Zhang, Et. Al., Clas Collaboration
Experimental Study Of Exclusive ²H(E,E'P)N Reaction Mechanisms At High Q², S. E. Kuhn, M. J. Amaryan, H. Bagdasaryan, M. Bektasoglu, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, N. Guler, C. E. Hyde-Wright, H. G. Juengst, N. Kalantarians, A. Klein, M. R. Niroula, R. A. Niyazov, S. Tkachenko, L. B. Weinstein, J. Zhang, Et. Al., Clas Collaboration
Physics Faculty Publications
The reaction 2H(e,e(')p)n has been studied with full kinematic coverage for photon virtuality 1.75 < Q2< 5.5 GeV2. Comparisons of experimental data with theory indicate that for very low values of neutron recoil momentum (pn< 100 MeV/c) the neutron is primarily a spectator and the reaction can be described by the plane-wave impulse approximation. For 100 < pn< 750 MeV/c, proton-neutron rescattering dominates the cross section, while Delta production followed by the NΔ → NN transition is the primary contribution at higher momenta.
First Measurement Of Beam-Recoil Observables CX And CZ In Hyperon Photoproduction, M. J. Amaryan, H. Bagdasaryan, H. Bektasoglu, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, N. Guler, C. E. Hyde-Wright, N. Kalantarians, A. Klein, S. E. Kuhn, J. Lachniet, M. R. Niroula, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, Et Al., Clas Collaboration
First Measurement Of Beam-Recoil Observables CX And CZ In Hyperon Photoproduction, M. J. Amaryan, H. Bagdasaryan, H. Bektasoglu, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, N. Guler, C. E. Hyde-Wright, N. Kalantarians, A. Klein, S. E. Kuhn, J. Lachniet, M. R. Niroula, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, Et Al., Clas Collaboration
Physics Faculty Publications
Spin transfer from circularly polarized real photons to recoiling hyperons has been measured for the reactions →γ + p → K+ + →Λ and →γ+p → K+ + →Σ0. The data were obtained using the CEBAF Large Acceptance Spectrometer (CLAS) detector at the Jefferson Lab for center-of-mass energies W between 1.6 and 2.53 GeV, and for -0.85 < cos θc.m.K+ < +0.95. For the Λ, the polarization transfer coefficient along the photon momentum axis, Cz, was found to be near unity for a wide range of energy and kaon production angles. The associated transverse polarization coefficient Cx is smaller than Cz by a roughly …
Measurement Of Coherent ɸ-Meson Photoproduction From The Deuteron At Low Energies, M. J. Amaryan, H. Bagdasaryan, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde-Wright, A. V. Klimenko, S. E. Kuhn, S. Tkachenko, L. B. Weinstein, Et. Al., Clas Collaboration
Measurement Of Coherent ɸ-Meson Photoproduction From The Deuteron At Low Energies, M. J. Amaryan, H. Bagdasaryan, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde-Wright, A. V. Klimenko, S. E. Kuhn, S. Tkachenko, L. B. Weinstein, Et. Al., Clas Collaboration
Physics Faculty Publications
The cross section and decay angular distributions for the coherent ɸ-meson photoproduction on the deuteron have been measured for the first time up to a squared four-momentum transfer t = (pᵧ - pɸ)2 =-2 GeV2/c2, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cross sections are compared with predictions from a rescattering model. In a framework of vector meson dominance, the data are consistent with the total ɸ-N cross section σɸN at about 10 mb. If vector meson dominance is violated, a larger σɸN is possible by introducing a …
Cross Sections For The 𝛾p -> K*⁰ Σ⁺ Reaction At E𝛾 = 1.7-3.0 Gev, M. Amarian, H. Bagdasaryan, S. Bültmann, S. L. Careccia, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde-Wright, A. Klein, A. V. Klimenko, S. E. Kuhn, M. R. Niroula, S. Tkachenko, L. B. Weinstein, J. Zhang, Et Al., The Clas Collaboration
Cross Sections For The 𝛾p -> K*⁰ Σ⁺ Reaction At E𝛾 = 1.7-3.0 Gev, M. Amarian, H. Bagdasaryan, S. Bültmann, S. L. Careccia, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde-Wright, A. Klein, A. V. Klimenko, S. E. Kuhn, M. R. Niroula, S. Tkachenko, L. B. Weinstein, J. Zhang, Et Al., The Clas Collaboration
Physics Faculty Publications
Differential cross sections for the reaction 𝛾p→ K*0Σ+ are presented in the photon energy range of 1.7 to 3.0 GeV. The K*0 was detected by its decay products, K+π−, in the Continuous Electron Beam Accelerator Facility's large acceptance spectrometer (CLAS) detector at the Thomas Jefferson National Accelerator Facility. These data are the first K*0 photoproduction cross sections ever published over a broad range of angles. Comparison with a theoretical model based on the vector and tensor K∗-quark couplings shows good agreement with the data, except at forward angles, suggesting that …
A General Model Of Resistive Wall Instability In Linear Accelerators, Jean R. Delayen
A General Model Of Resistive Wall Instability In Linear Accelerators, Jean R. Delayen
Physics Faculty Publications
A general model for wakefield-generated instabilities in linear accelerators, originally developed for cumulative beam breakup [1], is applied to the resistive wall instability. The general solution for various bunch charge distributions and application to various accelerator configurations are presented.