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1997

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Articles 271 - 300 of 327

Full-Text Articles in Physics

The Interaction Of A Point Vortex With A Wall-Bounded Vortex Layer, Oliver V. Atassi, Andrew J. Bernoff, Seth Lichter Jan 1997

The Interaction Of A Point Vortex With A Wall-Bounded Vortex Layer, Oliver V. Atassi, Andrew J. Bernoff, Seth Lichter

All HMC Faculty Publications and Research

The interaction of a point vortex with a layer of constant vorticity, bounded below by a wall and above by an irrotational flow, is investigated as a model of vortex–boundary layer interaction. This model calculates both the evolution of the interface which separates the vortex layer from the irrotational flow and the trajectory of the vortex. In order to determine the conditions which lead to sustained unsteady interaction, three cases are investigated where the mutual interaction between the vortex and interface is initially assumed to be weak. (i) When a weak point vortex lies outside the layer, the vortex moves …

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Depth Measurement Of Doped Semiconductors Using The Hall Technique, G. C. Desalvo, David C. Look, Christopher A. Bozada, J. L. Ebel Jan 1997

Depth Measurement Of Doped Semiconductors Using The Hall Technique, G. C. Desalvo, David C. Look, Christopher A. Bozada, J. L. Ebel

Physics Faculty Publications

No abstract provided.

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Separating K+/- From Pi+/- Using In-Flight Decays To Mu+/- + Nu, Wilfred J. Braithwaite, Edwin S. Braithwaite Jan 1997

Separating K+/- From Pi+/- Using In-Flight Decays To Mu+/- + Nu, Wilfred J. Braithwaite, Edwin S. Braithwaite

Journal of the Arkansas Academy of Science

A method is presented for completely distinguishing between charged kaons and charged pions by using their charged muon (plus neutrino) decays (with neutrinos undetected) for meson laboratory momenta up to 1000 MeV/c. When either a charged kaon or a charged pion decays into a muon and a neutrino, momentum-energy (four-momentum) conservation will be used to provide unique "kinematic trajectories" for distinguishing kaon decays from pion decays when the change in three-momentum of the muon from that of either parent kaon or pion is measured (or simulated). Ina magnetic field, observation of a tracked particle showing a "kink" and/or a change …

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Identification Of Electron-Irradiation Defects In Semi-Insulating Gaas By Normalized Thermally Stimulated Current Measurements, David C. Look, Z-Q. Fang, Joseph W. Hemsky, P. Kengkan Jan 1997

Identification Of Electron-Irradiation Defects In Semi-Insulating Gaas By Normalized Thermally Stimulated Current Measurements, David C. Look, Z-Q. Fang, Joseph W. Hemsky, P. Kengkan

Physics Faculty Publications

No abstract provided.

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Electromagnetic Reaction Cross Sections In Relativistic Heavy Ion Collisions, Jack Dostal Jan 1997

Electromagnetic Reaction Cross Sections In Relativistic Heavy Ion Collisions, Jack Dostal

Presidential Scholars Theses (1990 – 2006)

The goal of this project was to produce a computer program to predict the cross section of relativistic heavy ion collisions between given projectile and target nuclei. An explanation of the usefulness of relativistic heavy ion collision analysis is presented. The use of the Weiszacker-Williams method of virtual quanta for enhancing reaction cross sections of this type is discussed. Quantum-mechanical corrections to the semiclassical Weiszacker-Williams method are introduced. C++ computer code has been developed to calculate both semiclassical (as a check) and quantum-mechanical cross sections for these types of reactions. Preliminary results are given for the heavy ion reaction ( …

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General Remarks On Spectral Entropy Vs. Statistical Entropy, John D. Ramshaw Jan 1997

General Remarks On Spectral Entropy Vs. Statistical Entropy, John D. Ramshaw

Physics Faculty Publications and Presentations

Crepeau and Herzel [1] (CH) have recently compared the spectral entropy of Powell and Percival [2] with the standard statistical (Boltzmann-Gibbs-Shannon) entropy in three simple physical systems. Here we compare and contrast these two entropies in a more general way by considering their values for an arbitrary stationary process X(t).

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Projectile Charge-State Dependence On Final-State Momentum Distributions For Single Ionization Of Helium, C. J. Wood, C. R. Feeler, Ronald E. Olson Jan 1997

Projectile Charge-State Dependence On Final-State Momentum Distributions For Single Ionization Of Helium, C. J. Wood, C. R. Feeler, Ronald E. Olson

Physics Faculty Research & Creative Works

Single-ionization cross sections and final-state momentum distributions have been calculated for the single-ionization collision reactions H[Formula Presented], [Formula Presented], He[Formula Presented], C[Formula Presented], and C[Formula Presented] + He at 100 keV/u. The classical trajectory Monte Carlo method has been used with a Wigner distribution to improve both the He electron classical radial and momentum distributions. Final-state ionized electron momenta are projected into a collision plane defined by the initial projectile momentum and the final transverse component of the He[Formula Presented] recoil momentum, with the results displayed differentially in various components of electron and recoil momenta. Positively charged projectile impact shows …

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Semiclassical Approach To The Hydrogen-Exchange Reaction Reactive And Transition-State Dynamics, Sophya V. Garashchuk, F. Grossmann, D. Tannor Jan 1997

Semiclassical Approach To The Hydrogen-Exchange Reaction Reactive And Transition-State Dynamics, Sophya V. Garashchuk, F. Grossmann, D. Tannor

Faculty Publications

Scattering matrix elements and symmetric transition-state resonances for the collinear H 2 + H → H + H 2 reaction are obtained using a time-dependent approach. The correlation function between reactant channel wavepackets and product channel wavepackets is used to determine the S-matrix elements. In a similar fashion, autocorrelation functions are used to extract the positions and widths of transition-state resonances. The time propagation of the wavepackets is performed by the improved semiclassical frozen Gaussian method of Herman and Kluk, which is an initial value, uniformly converged method. The agreement between the quantum and semiclassical results is far better …

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Droplet Concentration And Size Distribution In Haze And Fog, Josef Podzimek Jan 1997

Droplet Concentration And Size Distribution In Haze And Fog, Josef Podzimek

Physics Faculty Research & Creative Works

Fog (haze) droplet concentrations and size distributions were measured at five sampling sites representing rural and urban regions and a highly polluted marine-urban environment. Droplet imprints in a thin gelatine layer were evaluated and compared to the measurement by light scattering instruments. This enabled conditions for the application of the logarithmic-normal size distribution and for the classification of typical fog droplet size distributions to be established. In particular, the parameters featuring the width and asymmetry of a size distribution were suggested and calculated. Advantages and drawbacks of the applied droplet sampling and evaluation technique are discussed in more detail. © …

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Momentum Spectra For Single And Double Electron Ionization Of He In Relativistic Collisions, C. J. Wood, Ronald E. Olson, W. Schmitt, R. Moshammer, J. Ullrich Jan 1997

Momentum Spectra For Single And Double Electron Ionization Of He In Relativistic Collisions, C. J. Wood, Ronald E. Olson, W. Schmitt, R. Moshammer, J. Ullrich

Physics Faculty Research & Creative Works

The complete momentum spectra for single and double ionization of He by [Formula Presented] [Formula Presented] [Formula Presented] have been investigated using a classical trajectory Monte Carlo method corrected for the relativistic projectile. The [Formula Presented] electron-electron interaction has been included in the post-collision region for double ionization to incorporate the effects of both the nuclear-electron and electron-electron ionizing interactions, and to access the effects of electron correlation in the electron spectra. Experimental measurements were able to determine the longitudinal momentum spectra for single ionization; these observations are in accordance with the theoretical predictions for the three-body momentum balance between …

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The Interaction Of Fast Alpha Particles With Pellet Ablation Clouds, J. M. Mcchesney, P. B. Parks, R. K. Fisher, Ronald E. Olson Jan 1997

The Interaction Of Fast Alpha Particles With Pellet Ablation Clouds, J. M. Mcchesney, P. B. Parks, R. K. Fisher, Ronald E. Olson

Physics Faculty Research & Creative Works

The energy spectra of energetic confined alpha particles are being measured using the pellet charge exchange method [R. K. Fisher, J. S. Leffler, A. M. Howald, and P. B. Parks, Fusion Technol. 13, 536 (1988)]. The technique uses the dense ablation cloud surrounding an injected impurity pellet to neutralize a fraction of the incident alpha particles, allowing them to escape from the plasma where their energy spectrum can be measured using a neutral particle analyzer. The signal calculations given in the above-mentioned reference disregarded the effects of the alpha particles' helical Larmor orbits, which causes the alphas to make multiple …

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Complete Momentum Balance For Single Ionization Of Helium By Fast Ion Impact: Experiment, R. Moshammer, J. Ullrich, H. Kollmus, W. Schmitt, M. Unverzagt, H. Schmidt-Böcking, C. J. Wood, Ronald E. Olson Jan 1997

Complete Momentum Balance For Single Ionization Of Helium By Fast Ion Impact: Experiment, R. Moshammer, J. Ullrich, H. Kollmus, W. Schmitt, M. Unverzagt, H. Schmidt-Böcking, C. J. Wood, Ronald E. Olson

Physics Faculty Research & Creative Works

The collision dynamics of He single ionization by [Formula Presented] impact was explored using the reaction microscope of the Gesellschaft für Schwerionenforschung, a high-resolution integrated multielectron recoil-ion momentum spectrometer. The complete three-particle final-state momentum distribution (nine Cartesian components [Formula Presented]) was imaged with a resolution of [Formula Presented] by measuring the three momentum components of the emitted electron and the recoiling target ion in coincidence. The projectile energy loss has been determined on a level of [Formula Presented] and projectile scattering angles as small as [Formula Presented] became accessible. The experimental data which are compared with results of classical trajectory …

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Observation Of Upper Tropospheric Sulfur Dioxide- And Acetone-Pollution: Potential Implications For Hydroxyl Radical And Aerosol Formation, F. Arnold, J. Schneider, K. Gollinger, H. Schlager, P. Schulte, Donald E. Hagen, Philip D. Whitefield, Peter F. J. Van Velthoven Jan 1997

Observation Of Upper Tropospheric Sulfur Dioxide- And Acetone-Pollution: Potential Implications For Hydroxyl Radical And Aerosol Formation, F. Arnold, J. Schneider, K. Gollinger, H. Schlager, P. Schulte, Donald E. Hagen, Philip D. Whitefield, Peter F. J. Van Velthoven

Physics Faculty Research & Creative Works

Aircraft-based measurements of sulfur dioxide, acetone, carbon dioxide, and condensation nuclei (CN) were made over the north-eastern Atlantic at upper tropospheric altitudes, around 9000 m. On October 14, 1993, strong SO 2- and acetone-pollution (both up to 3 ppbv) were observed, which were accompanied by a CO 2-enhancement of up to 6 ppmv, and large CN-concentrations of up to about 1500 cm -3 (for radii ≥ 6 nm). CN, excess CO 2, and to a lesser degree also acetone, were positively correlated with SO 2. Air mass trajectory analyses indicate, that most of the air masses …

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Real Time 3-D Video Moire Inspection System With Enhanced Depth Resolution, Donald W.W. Dawson, Chris L. Hart, Bernard R. Gilbert, Gary L. Wallace, Joel H. Blatt Jan 1997

Real Time 3-D Video Moire Inspection System With Enhanced Depth Resolution, Donald W.W. Dawson, Chris L. Hart, Bernard R. Gilbert, Gary L. Wallace, Joel H. Blatt

Aerospace, Physics, and Space Science Faculty Publications

A variable resolution video machine vision systems has been built which generates twice the number of depth contours for a given grating spacing as a conventional moiré system. This variable resolution system uses a Mach-Zender interferometer to project interference fringes onto a reference surface and onto a target surface. Video images of the two structurally illuminated surfaces are mixed in a video mixer with the resulting output being moiré contours which are the intersections of the two surfaces. If the reference surface is a flat plate, we get equal depth contours of the target surface, and if the reference surface …

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Analysis Of Scanning Tunneling Optical Spectroscopy Applied To Narrow Gap Semiconductors, James D. Patterson, James G. Mantovani Jan 1997

Analysis Of Scanning Tunneling Optical Spectroscopy Applied To Narrow Gap Semiconductors, James D. Patterson, James G. Mantovani

Aerospace, Physics, and Space Science Faculty Publications

Homogeneous II-VI narrow gap semiconducting alloys are of interest because of their use in infrared detectors. These compound semiconductor materials are inherently difficult to grow in bulk due to gravity induced convective flows. A microgravity growth environment has therefore been considered. In order to evaluate the quality of crystals grown in space compared to those grown on the ground, it is necessary to characterize both. One important aspect of this characterization is the study of stoichiometry, x. A characterization scheme using scanning tunneling optical spectroscopy (STOS) involves determining the spectral response of the photoexcited tunneling current for a semiconductor. By …

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Prediction Of Firing Pin Shape And 3d Matching Of Shells And Firing Pins Based On Firing Pin Impressions In Primers, Donald W. Dawson, Chris Hart, Bernard S. Gilbert Iii, Rafael A. Andrade, Joel H. Blatt Jan 1997

Prediction Of Firing Pin Shape And 3d Matching Of Shells And Firing Pins Based On Firing Pin Impressions In Primers, Donald W. Dawson, Chris Hart, Bernard S. Gilbert Iii, Rafael A. Andrade, Joel H. Blatt

Aerospace, Physics, and Space Science Faculty Publications

A variable resolution video machine vision system has been built which will determine the 3-D shape of a firing pin from the dent it has made in the primer of a shell. The system can also compare primer dents in different shells and determine if a 3-D match exists. A real time optical 3-D shape recognition feature allows the operator to align the shells, determine if there is a match, and quantify the quality of the 3-D match. The system uses a laser interferometer to project variable spatial frequency structural illumination on the shells which are viewed by video cameras. …

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Harmonic Oscillation In The Presence Of Multiple Damping Forces, Chris Pelto '97 Jan 1997

Harmonic Oscillation In The Presence Of Multiple Damping Forces, Chris Pelto '97

Honors Projects

The relatively mundane damped harmonic oscillator is found to exhibit interesting motion once under the influence of both a velocity dependent and a Coulombic frictional damping force. Data for the decay of the amplitude as a function of time were collected on a specially prepared torsional oscillator. with a variable electromagnetic damping mechanism. An analytical solution of the appropriate equation of motion was obtained by the method of Laplace transforms. In both the limits of zero Coulombic friction and zero velocity damping, the solution reduces to the well-known answers to the problem. the solution, when plotted with the correct parameters, …

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Classical Interpretation Of The Quantum Description Of H- Photodetachment In Parallel E And B Fields, Qiaoling Wang, Anthony F. Starace Jan 1997

Classical Interpretation Of The Quantum Description Of H- Photodetachment In Parallel E And B Fields, Qiaoling Wang, Anthony F. Starace

Anthony F. Starace Publications

Total quantum mechanical cross sections for photodetachment of H- in parallel E and B fields are examined both analytically and numerically to extract information which has a classical interpretation, thereby complementing recent classical and semiclassical periodic orbit studies.

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The Interaction Of Naphthoquinones With The Calcium Release Channel Of Skeletal Muscle Sarcoplasmic Reticulum, Ruohong Xia Jan 1997

The Interaction Of Naphthoquinones With The Calcium Release Channel Of Skeletal Muscle Sarcoplasmic Reticulum, Ruohong Xia

Dissertations and Theses

The sarcoplasmic reticulum (SR) is an intracellular membrane system which regulates cytoplasmic calcium concentration in muscle and controls the contractile state of muscle. In this thesis, the interaction between naphthoquinone and the Ca2+ release mechanism of SR is described. 1,4-naphthoquinone (1,4NQ) is shown to stimulate Ca2+ release and to modify high-affinity ryanodine binding to skeletal muscle sarcoplasmic reticulum. The interaction between 1,4NQ and the SR involves the oxidation ofcritical sulfhydryl groups associated with the Ca2+ release mechanism. The modulation of ryanodine binding by 1,4NQ is biphasic. At low concentrations of 1,4NQ (<10 >μM) ryanodine binding is stimulated, …

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Summing Up: Questions And Answers On The Comprehensive Test Ban Treaty, David W. Hafemeister Jan 1997

Summing Up: Questions And Answers On The Comprehensive Test Ban Treaty, David W. Hafemeister

Physics

My experiences with the ratification of the Strategic Arms Reduction Treaty, the Threshold Test Ban Treaty, and the Conventional Armed Forces in Europe Treaty have led me to conclude that presenting technical issues early in the process greatly reduces their politicization during the ratification end game. This chapter summarizes the important issues that will be raised during the debate on ratification of the Comprehensive Test Ban Treaty. It uses a compact question and answer format to cover the following topics: I. Nuclear Proliferation, II. Nuclear Arms Control, III. Warhead Reliability and Yield for National Security, IV. Warhead Safety, V. Verification, …

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The Effect Of Three-Dimensional Freestream Disturbances On The Supersonic Flow Past A Wedge, Peter W. Duck, D. Glenn Lasseigne, M. Y. Hussaini Jan 1997

The Effect Of Three-Dimensional Freestream Disturbances On The Supersonic Flow Past A Wedge, Peter W. Duck, D. Glenn Lasseigne, M. Y. Hussaini

Mathematics & Statistics Faculty Publications

The interaction between a shock wave (attached to a wedge) and small amplitude, three-dimensional disturbances of a uniform, supersonic, freestream flow are investigated. The paper extends the two-dimensional study of Duck et al. [P W. Duck, D. G. Lasseigne, and M. Y. Hussaini, ''On the interaction between the shock wave attached to a wedge and freestream disturbances,'' Theor. Comput. Fluid Dyn. 7, 119 (1995) (also ICASE Report No. 93-61)] through the use of vector potentials, which render the problem tractable by the same techniques as in the two-dimensional case, in particular by expansion of the solution by means of …

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Velocity–Space Drag And Diffusion In A Model, Two-Dimensional Plasma, Mark Anthony Reynolds, B.D. Fried, G.J. Morales Jan 1997

Velocity–Space Drag And Diffusion In A Model, Two-Dimensional Plasma, Mark Anthony Reynolds, B.D. Fried, G.J. Morales

Publications

The quasilinear fluctuation integral is calculated for a two-dimensional, unmagnetized plasma ~composed of charged rods!, and is expressed in terms of Fokker–Planck coefficients. It is found that in two dimensions, the enhanced fluctuations generated by fast electrons lead to anomalously large transport coefficients. In particular, the effect of a small population of fast electrons is only weakly dependent on their density. In three dimensions, the effect of fast electrons is masked by the dominant approximation, but higher-order terms describe processes similar to those in two dimensions, and these terms can become significant for weakly stable plasmas. The differences between two …

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Effect Of Diurnal Convection On Trapped Thermal Plasma In The Outer Plasmasphere, Mark Anthony Reynolds, G. Ganguli, J.A. Fedder, D.J. Melendez-Alvira Jan 1997

Effect Of Diurnal Convection On Trapped Thermal Plasma In The Outer Plasmasphere, Mark Anthony Reynolds, G. Ganguli, J.A. Fedder, D.J. Melendez-Alvira

Publications

A kinetic, multi‐species model of the plasmasphere is constructed that includes the effect of convection and corotation electric fields on trapped particles in drifting flux tubes. The resulting morphology of the outer plasmasphere is significantly different from the morphology obtained using the assumption of diffusive equilibrium. The difference is due primarily to the contraction and expansion of the region of velocity space accessible to the trapped particles, and has implications for the interpretation of remote sensing experiments.

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Gdr In Superdeformed Nuclei, F. Camera, A. Bracco, A. Atac, R. Bark, I. G. Bearden, J. J. Gaardhoje, B. Herskind, M. Kmiecik, S. Leoni, M. Mattiuzzi, A. Maj, G. Turri Jan 1997

Gdr In Superdeformed Nuclei, F. Camera, A. Bracco, A. Atac, R. Bark, I. G. Bearden, J. J. Gaardhoje, B. Herskind, M. Kmiecik, S. Leoni, M. Mattiuzzi, A. Maj, G. Turri

Publications

A search for the gamma decay of the Giant Dipole Resonance built on superdeformed nuclear configurations was made. The superdeformed states of the Eu-143 nucleus were populated using the reaction Pd-110(Cl-37, 4n)Eu-143 at a beam energy of 165 MeV. High energy gamma-rays were detected in 8 large BaF2 scintillators in coincidence with discrete transitions measured with part of the NORDBALL array (17 HPGe detectors and a 2 pi multiplicity filter). Spectra of high-energy gamma-rays gated by low-energy transitions from states fed by the superdeformed bands show an excess yield in the 7-10 MeV region with respect to those gated by …

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H2s Adsorption On Chromium, Chromia, And Gold/Chromia Surfaces: Photoemission Studies, J A. Rodriguez, S Chaturvedi, U Diebold, M Kuhn, J Van Ek, P S. Robbert, H Geisler, C A. Ventrice Jr Jan 1997

H2s Adsorption On Chromium, Chromia, And Gold/Chromia Surfaces: Photoemission Studies, J A. Rodriguez, S Chaturvedi, U Diebold, M Kuhn, J Van Ek, P S. Robbert, H Geisler, C A. Ventrice Jr

Physics Faculty Publications

The reaction of H2S with chromium, chromia, and Au/chromia films grown on a Pt(111) crystal has been investigated using synchrotron-based high-resolution photoemission spectroscopy. At 300 K, H2S completely decomposes on polycrystalline chromium producing a chemisorbed layer of S that attenuates the Cr 3d valence features. No evidence was found for the formation of CrSx species. The dissociation of H2S on Cr3O4 and Cr2O3 films at room temperature produces a decrease of 0.3–0.8 eV in the work function of the surface and significant binding-energy shifts (0.2–0.6 eV) …

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Intrinsic Chaos In A Dc Field Biased Quantum Heterostructure, A. Jason Mcnary, Ashok Puri Jan 1997

Intrinsic Chaos In A Dc Field Biased Quantum Heterostructure, A. Jason Mcnary, Ashok Puri

Physics Faculty Publications

A closed, quantum, double barrier, GaAs/AlGaAs heterostructure is made chaotic by adding a nonlinear potential term, α〈Q(t)〉, to the time-dependent Schrödinger equation, and the dynamical behavior of an electron cloud moving in the heterostructure biased by a dc electric field is examined numerically. Using phase-space diagrams, power spectrums, and Lyapunov exponents, both qualitative and quantitative measures of the chaos in the system were taken. In general, for all values of α, the nonlinearity parameter, the Lyapunov exponent, λ, increases as the applied dc field, β, increases. However, for values of α ⩽ 1.376, we notice …

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Optical Studies Of Ge Islanding On Si(111), P. D. Persans, P. W. Deelman, K. L. Stokes, L. J. Schowalter, A. Byrne, T. Thundat Jan 1997

Optical Studies Of Ge Islanding On Si(111), P. D. Persans, P. W. Deelman, K. L. Stokes, L. J. Schowalter, A. Byrne, T. Thundat

Physics Faculty Publications

We report an experimental study of the optical properties of island layers resulting from molecular beam epitaxial deposition of Ge on Si(111) substrates. The combination of electroreflectance spectroscopy of the E1 transition and Raman scattering allows us to separately determine the strain and composition of the islands. For deposition at 500 °C a deposited layer of 1.36 nm of Ge assembles into 80 nm diameter islands 11 nm thick. The average Si impurity content in the islands is 2.5% while the average in-plane strain is 0.5%. Both strain and Si impurity content in islands decrease with increasing Ge deposition

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Measurement Of Inelastic J/Ψ Photoproduction At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti Jan 1997

Measurement Of Inelastic J/Ψ Photoproduction At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

No abstract provided.

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Measurement Of Elastic J/Ψ Photoproduction St Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti Jan 1997

Measurement Of Elastic J/Ψ Photoproduction St Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

The reaction γ p → J/ψ p has been studied in ep interactions using the ZEUS detector at HERA. The cross section for elastic J/ψ photoproduction has been measured as a function of the photon-proton centre of mass energy W in the range 40 < W < 140 GeV at a median photon virtuality Q2 of 5 × 10-5 GeV2. The photoproduction cross section, σγp→J/ψp, is observed to rise steeply with W. A fit to the data presented in this paper to determine the parameter δ in the form σγp→J/ψp α Wδ yields the value δ = 0.92±0.14±0.10. The differential cross section dσ/d|t| is presented over the range |t| < 1.0 GeV2 where t is the square of the four-momentum exchanged at the proton vertex. dσ/d|t| falls exponentially with a slope parameter of 4.6 ± 0.4-0.6+0.4 GeV-2. The measured decay angular distributions are consistent with s-channel helicity conservation. © Springer-Verlag 1997.

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Comparison Of Zeus Data With Standard Model Predictions For E+P → E+X Scattering At High X And Q2, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti Jan 1997

Comparison Of Zeus Data With Standard Model Predictions For E+P → E+X Scattering At High X And Q2, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

Using the ZEUS detector at HERA, we have studied the reaction e+p → e+X for Q2 > 5000 GeV2 with a 20.1 pb-1 data sample collected during the years 1994 to 1996. For Q2 below 15000 GeV2, the data are in good agreement with Standard Model expectations. For Q2 > 35000 GeV2, two events are observed while 0.145 ± 0.013 events are expected. A statistical analysis of a large ensemble of simulated Standard Model experiments indicates that with probability 6.0%, an excess at least as unlikely as that observed would occur above some Q2 cut. For x > 0.55 and y > 0.25, four …

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