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Articles 31411 - 31440 of 36658

Full-Text Articles in Physical Sciences and Mathematics

Numerical Simulations Of Gravity Waves Imaged Over Arecibo During The 10-Day January 1993 Campaign, M. P. Hickey, R. L. Walterscheid, Michael J. Taylor, W. Ward, G. Schubert, Q. Zhou, F. Garcia, M. C. Kelley, G. G. Shepherd Jun 1997

Numerical Simulations Of Gravity Waves Imaged Over Arecibo During The 10-Day January 1993 Campaign, M. P. Hickey, R. L. Walterscheid, Michael J. Taylor, W. Ward, G. Schubert, Q. Zhou, F. Garcia, M. C. Kelley, G. G. Shepherd

All Physics Faculty Publications

Recently, measurements were made of mesospheric gravity waves in the OI (5577 Å) nightglow observed from Arecibo, Puerto Rico, during January 1993 as part of a special 10-day campaign. Clear, monochromatic gravity waves were observed on several nights. By using a full-wave model that realistically includes the major physical processes in this region, we have simulated the propagation of two waves through the mesopause region and calculated the O(1 S) nightglow response to the waves. Mean winds derived from both UARS wind imaging interferometer (WINDII) and Arecibo incoherent scatter radar observations were employed in the computations as were the climatological …

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High-Order Interior Caustics Produced In Scattering Of A Diagonally Incident Plane Wave By A Circular Cylinder, Charles L. Adler, James A. Lock, Bradley R. Stone, Claudio J. Garcia Jun 1997

High-Order Interior Caustics Produced In Scattering Of A Diagonally Incident Plane Wave By A Circular Cylinder, Charles L. Adler, James A. Lock, Bradley R. Stone, Claudio J. Garcia

Physics Faculty Publications

We examine scattering of a family of initially parallel diagonally incident rays by a dielectric circular cylinder and show that the interior and exterior caustics that occur are qualitatively identical to those produced at normal incidence. We find, however, that (1) varying the plane-wave tilt angle has the same effect on the caustics as varying the refractive index of the cylinder at normal incidence and (2) high-order interior caustics are visible because of larger internal-reflection Fresnel coefficients at diagonal incidence than at normal incidence. We also observe noncaustic ray trajectories produced by the sharp peaking of internal-reflection Fresnel coefficients at …

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The Equation Of State For Two Flavor Qcd At N_T=6, James E. Hetrick, C. Bernard Jun 1997

The Equation Of State For Two Flavor Qcd At N_T=6, James E. Hetrick, C. Bernard

All Faculty Articles - School of Engineering and Computer Science

We improve the calculation of the equation of state for two flavor QCD by simulating on Nt = 6 lattices at appropriate values of the couplings for the deconfinement/chiral symmetry restoration crossover. For amq = 0.0125 the energy density rises rapidly to approximately 1 GeV/fm3 just after the crossover (mπ/mρ ≈ 0.4 at this point). Comparing with our previous result for Nt = 4 [1], we find large finite Nt corrections as expected from free field theory on finite lattices. We also provide formulae for extracting the speed of sound from the measured quantities.

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Production Of Η Mesons In Double Pomeron Exchange, Alec Schramm, Daniel Reeves May 1997

Production Of Η Mesons In Double Pomeron Exchange, Alec Schramm, Daniel Reeves

Alec J Schramm

We estimate the production cross section for ηc and ηb mesons via Pomeron-Pomeron fusion in peripheral heavy-ion collisions. Total and elastic PP cross sections are calculated in an equivalent Pomeron approximation.

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Differential Cross Sections Of D*± Photoproduction In Ep Collisions 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, R. 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, I. Gialas, R. Giusti, G. Iacobucci, G. Laurenti, G. Levi May 1997

Differential Cross Sections Of D*± Photoproduction In Ep Collisions 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, R. 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, I. Gialas, R. Giusti, G. Iacobucci, G. Laurenti, G. Levi

Faculty Publications

Inclusive photoproduction of D*± in ep collisions at HERA has been measured with the ZEUS detector for photon-proton centre of mass energies in the range 115 < W < 280 GeV and photon virtuality Q2 < 4 GeV2. The cross section σ → D*X integrated over the kinematic region pDz.ast;⊥ > 3 GeV and -1.5 < ηD* < 1.0 is (10.6 ± 1.7(stat.) ± 1.61.3 (syst.)) nb. Differential cross sections as functions of pD*⊥, ηD* and W are given. The data are compared with two next-to-leading order perturbative QCD predictions. For a calculation using a massive charm scheme the predicted cross sections are smaller than the measured ones. A recent calculation using a massless charm scheme is in agreement with the data. © 1997 Published by Elsevier Science B.V.

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First Energetic Neutral Atom Images From Polar, M. G. Henderson, G. D. Reeves, Harlan E. Spence, R. B. Sheldon, A. M. Jorgensen, J. B. Blake, J. F. Fennell May 1997

First Energetic Neutral Atom Images From Polar, M. G. Henderson, G. D. Reeves, Harlan E. Spence, R. B. Sheldon, A. M. Jorgensen, J. B. Blake, J. F. Fennell

Physics & Astronomy

Energetic neutral atoms are created when energetic magnetospheric ions undergo charge exchange with cold neutral atoms in the Earth's tenuous extended atmosphere (the geocorona). Since they are unaffected by the Earth's magnetic field, these energetic neutrals travel away in straight line trajectories from the points of charge exchange. The remote detection of these particles provides a powerful means through which the global distribution and properties of the geocorona and ring current can be inferred. Due to its 2 × 9 RE polar orbit, the Polar spacecraft provides an excellent platform from which to observe ENAs because it spends much of …

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Molecular Fluorescence At A Rough Surface: The Orientation Effects, William Lee Blacke May 1997

Molecular Fluorescence At A Rough Surface: The Orientation Effects, William Lee Blacke

Dissertations and Theses

The interaction between an emitting molecular dipole and a conducting substrate with a periodic surface roughness is looked at with particular interest in the different orientations of the dipole with respect to the substrate surface. A previous dynamical, perturbative theory for the effects of perpendicular dipole is extended to treat a dipole oriented parallel to the surface of the substrate. The results are then applied to study the modified fluorescence characteristics of the emitting dipoles. Numerical results demonstrate that some fluorescence characteristics are extremely sensitive to the molecular orientation with the dipole oriented along the grating (x direction) exhibiting unique …

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Optimization And Spectrophotometric Comparisons Of Radiochromic Dye (2,3,5-Triphenyl-2-H-Tetrazolium Chloride) In Gelatin And Agar Models: Gamma And Electron Beam Irradiations, Lakindra P. Frances May 1997

Optimization And Spectrophotometric Comparisons Of Radiochromic Dye (2,3,5-Triphenyl-2-H-Tetrazolium Chloride) In Gelatin And Agar Models: Gamma And Electron Beam Irradiations, Lakindra P. Frances

Electronic Dissertations and Theses

After irradiation, the colorless radiochromic dye, 2,3,5-triphenyl-2H-tetrazolium chloride (TTC), changes to red triphenyl formazan pigment, and the distribution of absorbed dose in the tissue-equivalent gelatin and agar media can be studied. Using solutions 8% by weight gelatin and 8% by weight agar, both with 3 mM citric acid as buffer and 4 mM concentration of dye, the radiation-induced absorbency of a sample slowly decreased with increasing wavelength. In the gel, TTC is very light sensitive, and 7 days after irradiation, becomes less stable. The samples were irradicated by gamma and electron beam. Nine different doses were used for the 60 …

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Experimental And Theoretical Investigations Of Order-Disorder In Cu2almn, Duane D. Johnson, M. Asta, J. J. Hoyt, B. C. Chakoumakos, S. T. Misture, J. D. Althoff, R. Mccormack May 1997

Experimental And Theoretical Investigations Of Order-Disorder In Cu2almn, Duane D. Johnson, M. Asta, J. J. Hoyt, B. C. Chakoumakos, S. T. Misture, J. D. Althoff, R. Mccormack

Duane D. Johnson

A combination of X-ray and neutron powder diffraction has been used to measure the two long range order parameters vs. temperature below the disorder-B2 transition in the ternary alloy Cu2 AlMn. The results indicate that at temperatures just below the critical point the Al + Mn sublattice is enriched in Al. First-principles calculations based on only the atomic numbers of Cu, Mn and Al support the experimentally-observed preference of Al for the Al + Mn sublattice, and reveal the interplay between the constituent binary systems that gives rise to this behavior.

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In Situ Observations Of Air Traffic Emission Signatures In The North Atlantic Flight Corridor, Hans Schlager, Paul Konopka, P. Schulte, U. Schumann, H. Ziereis, F. Arnold, M. Klemm, Donald E. Hagen, Philip D. Whitefield, J. Ovarlez May 1997

In Situ Observations Of Air Traffic Emission Signatures In The North Atlantic Flight Corridor, Hans Schlager, Paul Konopka, P. Schulte, U. Schumann, H. Ziereis, F. Arnold, M. Klemm, Donald E. Hagen, Philip D. Whitefield, J. Ovarlez

Physics Faculty Research & Creative Works

Focussed aircraft measurements have been carried out over the eastern North Atlantic to search for signals of air traffic emissions in the flight corridor region. Observations include NO, NO2, HNO3, SO2, O3, H2O, total condensation nuclei (CN), and meteorological parameters. A flight pattern with constant-altitude north-south legs across the major North Atlantic air traffic tracks was flown. Signatures of air traffic emissions were clearly detected for NOx, SO2, and CN with peak concentrations of 2 ppbv, 0.25 ppbv, and 500 cm-3, respectively, exceeding background …

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Steps Toward Determination Of The Size And Structure Of The Broad-Line Region In Active Galactic Nuclei. Ix. Ultraviolet Observations Of Fairall, P.M. Rodriguez-Pascual, D. Allion, J. Clavel, D. Michael Crenshaw, K. Horne, Gerard A. Kriss, Julian Henry Krolik, Matthew A. Malkan, Hagai Netzer, Paul T. O'Brien, Bradley M. Peterson, G.A. Reichert, W. Wamsteker, T. Alexander, P. Barr, R.D. Blandford, J.N. Bergman, T.E. Carone, S. Clements, T.-J. Courvoisier, M.M. De Robertis, M. Dietrich, H. Dottori, R.A. Edelson, A. V. Filippenko, C. Martin Gaskell, J. P. Huchra, J.B. Hutchings, W. Kollatschny, A.P. Koratkar, Kirk T. Korista, Ari Laor, G.M. Macalpine, P. G. Martin, D. Maoz, B. Mccollum, S.L. Morris, G.C. Perola, Richard William Pogge, R.L. Ptak, M.C. Recondo-Gonzalez, J.M. Rodriguez-Espinoza, E.L. Rokaki, M. Santos-Lleo, K. Sekiguchi, J.M. Schull, M.A.J. Snuders, L.S. Sparke, G.M. Stirpe, R.E. Stoner, W.-H. Sun, S.J. Wagner, I. Wanders, Belinda J. Wilkes, C. Winge, W. Zheng May 1997

Steps Toward Determination Of The Size And Structure Of The Broad-Line Region In Active Galactic Nuclei. Ix. Ultraviolet Observations Of Fairall, P.M. Rodriguez-Pascual, D. Allion, J. Clavel, D. Michael Crenshaw, K. Horne, Gerard A. Kriss, Julian Henry Krolik, Matthew A. Malkan, Hagai Netzer, Paul T. O'Brien, Bradley M. Peterson, G.A. Reichert, W. Wamsteker, T. Alexander, P. Barr, R.D. Blandford, J.N. Bergman, T.E. Carone, S. Clements, T.-J. Courvoisier, M.M. De Robertis, M. Dietrich, H. Dottori, R.A. Edelson, A. V. Filippenko, C. Martin Gaskell, J. P. Huchra, J.B. Hutchings, W. Kollatschny, A.P. Koratkar, Kirk T. Korista, Ari Laor, G.M. Macalpine, P. G. Martin, D. Maoz, B. Mccollum, S.L. Morris, G.C. Perola, Richard William Pogge, R.L. Ptak, M.C. Recondo-Gonzalez, J.M. Rodriguez-Espinoza, E.L. Rokaki, M. Santos-Lleo, K. Sekiguchi, J.M. Schull, M.A.J. Snuders, L.S. Sparke, G.M. Stirpe, R.E. Stoner, W.-H. Sun, S.J. Wagner, I. Wanders, Belinda J. Wilkes, C. Winge, W. Zheng

C. Martin Gaskell Publications

No abstract provided.

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Nickel Doping Of Boron–Carbon Alloy Films And Corresponding Fermi Level Shifts, Seong-Don Hwang, N. Remmes, Peter A. Dowben, D.N. Mcilroy May 1997

Nickel Doping Of Boron–Carbon Alloy Films And Corresponding Fermi Level Shifts, Seong-Don Hwang, N. Remmes, Peter A. Dowben, D.N. Mcilroy

Peter Dowben Publications

We have grown nickel doped boron–carbon alloy films by the technique of plasma enhanced chemical vapor deposition. The source gas closo-1,2-dicarbadodecaborane (orthocarborane) was used to grow the boron–carbon alloy, while nickelocene [Ni)C5H5)2] was used as the dopant source for nickel. With sufficient levels of Ni doping, diodes with characteristic tunnel diode behavior can be fabricated. The doping of nickel transformed a B5C p-type material, relative to lightly doped n-type silicon, to a strongly n-type material. In order to gain insight into the shift of the Fermi level of the …

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Nickel Doping Of Boron–Carbon Alloy Films And Corresponding Fermi Level Shifts, Seong-Don Hwang, N. Remmes, Peter A. Dowben, D.N. Mcilroy May 1997

Nickel Doping Of Boron–Carbon Alloy Films And Corresponding Fermi Level Shifts, Seong-Don Hwang, N. Remmes, Peter A. Dowben, D.N. Mcilroy

Peter Dowben Publications

We have grown nickel doped boron–carbon alloy films by the technique of plasma enhanced chemical vapor deposition. The source gas closo-1,2-dicarbadodecaborane (orthocarborane) was used to grow the boron–carbon alloy, while nickelocene [Ni(C5H5)2] was used as the dopant source for nickel. With sufficient levels of Ni doping, diodes with characteristic tunnel diode behavior can be fabricated. The doping of nickel transformed a B5C p-type material, relative to lightly doped n-type silicon, to a strongly n-type material. In order to gain insight into the shift of the Fermi level of the …

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Fabrication Of Micron Scale Magnetic Nickel Features By Selective Area Organometallic Chemical Vapor Deposition, D. Welipitiya, C.N. Borca, Peter A. Dowben May 1997

Fabrication Of Micron Scale Magnetic Nickel Features By Selective Area Organometallic Chemical Vapor Deposition, D. Welipitiya, C.N. Borca, Peter A. Dowben

Peter Dowben Publications

We demonstrate that it is possible to deposit a wide range of magnetic features, using photo-assisted and electron radiation induced selective area organometallic chemical vapor deposition. Large arrays of identical micron to nano scale Ni features were deposited by these methods. Their magnetic properties were studied by alternating gradient force magnetometry as well as magnetic force microscopy. Our morphological and magnetic measurements show that the structures are spatially well defined, and the magnetic properties are related to the structural shapes of the features.

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Studies Of Mid-Latitude Mesospheric Temperature Variability And Its Relationship To Gravity Waves, Tides, And Planetary Waves, Kenneth C. Beissner May 1997

Studies Of Mid-Latitude Mesospheric Temperature Variability And Its Relationship To Gravity Waves, Tides, And Planetary Waves, Kenneth C. Beissner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Temperature observations of the middle atmosphere have been carried out from September 1993 through July 1995 using a Rayleigh backscatter lidar located at Utah State University (42°N, 111°W). Data have been analyzed to obtain absolute temperature profiles from 40 to 90 km. Various sources of error were reviewed in order to ensure the quality of the measurements. This included conducting a detailed examination of the data reduction procedure, integration methods, and averaging techniques. eliminating errors of 1-3%. The temperature structure climatology has been compared with several other mid-latitude data sets. including those from the French lidars, the SME spacecraft, the …

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Computer Modeling Of Molecular Vibration Frequencies And Its Application To The Modeling Of Silane Compounds, Ryan T. Merrell May 1997

Computer Modeling Of Molecular Vibration Frequencies And Its Application To The Modeling Of Silane Compounds, Ryan T. Merrell

Honors Capstone Projects and Theses

No abstract provided.

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A Measurement Of Rb Using A Lifetime-Mass Tag, R. Barate, Manoj Thulasidas May 1997

A Measurement Of Rb Using A Lifetime-Mass Tag, R. Barate, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

ALEPH's published measurement of Rb = Γ(Ζ → bb̄)/Γ(Ζ → hadrons) using a lifetime tag is updated using the full LEP 1 data sample. Considerable effort has been devoted to understanding systematic effects. Charm background is better controlled by combining the lifetime tag with a tag based on the b/c hadron mass difference. Furthermore, the algorithm used to reconstruct the event primary vertex is designed so as to reduce correlations between the two hemispheres of an event. The value of Rb is measured to be 0.2167 ± 0.0011 (stat) ± 0.0013 (syst).

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Chaotic Behavior And Damage Spreading In The Glauber Ising Model: A Master Equation Approach, Thomas Vojta May 1997

Chaotic Behavior And Damage Spreading In The Glauber Ising Model: A Master Equation Approach, Thomas Vojta

Physics Faculty Research & Creative Works

We investigate the sensitivity of the time evolution of a kinetic Ising model with Glauber dynamics against the initial conditions. To do so we apply the "damage spreading" method, i.e., we study the simultaneous evolution of two identical systems subjected to the same thermal noise. We derive a master equation for the joint probability distribution of the two systems. We then solve this master equation within an effective-field approximation which goes beyond the usual mean-field approximation by retaining the fluctuations though in a quite simplistic manner. The resulting effective-field theory is applied to different physical situations. It is used to …

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Empirical Studies Of Ionospheric Electric Fields, Ludger Scherliess May 1997

Empirical Studies Of Ionospheric Electric Fields, Ludger Scherliess

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The first comprehensive study of equatorial- to mid-latitude ionospheric electric fields (plasma drifts) is presented, using extensive incoherent scatter radar measurements from Jicamarca, Arecibo, and Millstone Hill, and F-region ion drift meter data from the polar orbiting DE-2 satellite. Seasonal and solar cycle dependent empirical quiet-time electric field models from equatorial to mid latitudes are developed, which improve and extend existing climatological models. The signatures of electric field perturbations during geomagnetically disturbed periods, associated with changes in the high-latitude currents and the characteristics of storm-time dynamo electric fields driven by enhanced energy deposition into the high-latitude ionosphere, are studied. Analytical …

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Correlated And Coherent States Of The Two-Dimensional Quantum Oscillator With A Nonstationary Mode Coupling, Mikhail E. Veisman, Serguei Y. Kalmykov Apr 1997

Correlated And Coherent States Of The Two-Dimensional Quantum Oscillator With A Nonstationary Mode Coupling, Mikhail E. Veisman, Serguei Y. Kalmykov

Serge Youri Kalmykov

We investigate the squeezing and correlation phenomena of quantum fluctuations in correlated coherent states of a system of two oscillatory modes with a parametric coupling of the coordinates. In the regime of strong coupling between the modes, we discover an excitation and a strong correlation of the quantum fluctuations. The matrix of dispersions and covariances of the coordinates and momenta is found explicitly with the help of the method of the linear quantum integrals of motion.

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Analyses Of D+→KS0K+ And D+ → KS0Π+, M. Bishai, Kenneth A. Bloom, Cleo Collaboration Apr 1997

Analyses Of D+→KS0K+ And D+ → KS0Π+, M. Bishai, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

Using data collected with the CLEO II detector at the Cornell Electron Storage Ring, we present new measurements of the branching fractions for D+→KSK+and D+ → KSπ+ . These results are combined with other CLEO measurements to extract the ratios of isospin amplitudes and phase shifts for D → KK and D → K π.

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Intrinsic Decoherence In Mesoscopic Systems, P. Mohanty, E. M.Q. Jariwala, Richard A. Webb Apr 1997

Intrinsic Decoherence In Mesoscopic Systems, P. Mohanty, E. M.Q. Jariwala, Richard A. Webb

Faculty Publications

We present measurements of the phase coherence time τφ in six quasi-1D Au wires and clearly show that τφ is temperature independent at low temperatures. We suggest that zero-point fluctuations of the phase coherent electrons are responsible for the observed saturation of τφ. We introduce a new functional form for the temperature dependence and present the results of a calculation for the saturation value of τφ. This explains the observed temperature dependence of our samples as well as many 1D and 2D systems reported to date.

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Efficiency Of Molecular Hydrogen Formation On Silicates, Gianfranco Vidali, Valerio Pirronello, Ofer Biham, Chi Liu, Lyiong Shen Apr 1997

Efficiency Of Molecular Hydrogen Formation On Silicates, Gianfranco Vidali, Valerio Pirronello, Ofer Biham, Chi Liu, Lyiong Shen

Physics - All Scholarship

We report on laboratory measurements of molecular hydrogen formation and recombination on an olivine slab as a function of surface temperature under conditions relevant to those encountered in the interstellar medium. On the basis of our experimental evidence, we recognize that there are two main regimes of H coverage that are of astrophysical importance; for each of them we provide an expression giving the production rate of molecular hydrogen in interstellar clouds.

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Multiflavor Massive Schwinger Model With Non-Abelian Bosonization, Joseph Schechter, David Delphenich Apr 1997

Multiflavor Massive Schwinger Model With Non-Abelian Bosonization, Joseph Schechter, David Delphenich

Physics - All Scholarship

We revisit the treatment of the multiflavor massive Schwinger model by non-Abelian Bosonization. We compare three different approximations to the low-lying spectrum: i) reading it off from the bosonized Lagrangian (neglecting interactions), ii) semi-classical quantization of the static soliton, iii) approximate semi-classical quantization of the ``breather'' solitons. A number of new points are made in this process. We also suggest a different ``effective low-energy Lagrangian'' for the theory which permits easy calculation of the low-energy scattering amplitudes. It correlates an exact mass formula of the system with the requirement of the Mermin-Wagner theorem.

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Electron Acceleration By A Laser Wakefield In A Relativistically Self-Guided Channel, R. Wagner, Shouyuan Chen, Anatoly Maksimchuk, Donald P. Umstadter Apr 1997

Electron Acceleration By A Laser Wakefield In A Relativistically Self-Guided Channel, R. Wagner, Shouyuan Chen, Anatoly Maksimchuk, Donald P. Umstadter

Donald Umstadter Publications

Acceleration of electrons to relativistic energies by a multidimensional self-modulated laser wakefield is discussed. Above a power threshold, a relativistically self-guided channel from an intense ultrashort laser pulse (l∼4×1018 W/cm2, λ = 1 μm, τ = 400 fs) was found to increase the laser propagation distance, decrease the electron beam divergence, and increase the energy of the electrons. These electron beam effects occurred even though the propagation distance became significantly longer than the conventional dephasing length.

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Generalization Of The Bound State Model, Joseph Schechter, Masayasu Harada, Francesco Sannino, Herbert Weigel Apr 1997

Generalization Of The Bound State Model, Joseph Schechter, Masayasu Harada, Francesco Sannino, Herbert Weigel

Physics - All Scholarship

In the bound state approach the heavy baryons are constructed by binding, with any orbital angular momentum, the heavy meson multiplet to the nucleon considered as a soliton in an effective meson theory. We point out that this picture misses an entire family of states, labeled by a different angular momentum quantum number, which are expected to exist according to the geometry of the three-body constituent quark model (for N_C=3). To solve this problem we propose that the bound state model be generalized to include orbitally excited heavy mesons bound to the nucleon. In this approach the missing angular momentum …

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Magnetism And Morphology Of Fe/Cu(111) Films Below Two-Dimensional Percolation, J. Shen, Ralph Skomski, M. Klaua, H. Jenniches, S. Sundar Manoharan, J. Kirschner Apr 1997

Magnetism And Morphology Of Fe/Cu(111) Films Below Two-Dimensional Percolation, J. Shen, Ralph Skomski, M. Klaua, H. Jenniches, S. Sundar Manoharan, J. Kirschner

Ralph Skomski Publications

The magnetic properties of g-iron films on Cu(111) below the two-dimensional percolation threshold of about 1.4 monolayer are investigated. Iron on flat Cu(111) surfaces forms triangular patches, while it forms stripes along step edges on vicinal surfaces. The films exhibit an easy magnetization axis perpendicular to the film plane and magnetic hysteresis at sufficiently low temperatures. The magnetization curves of the triangular iron patches are discussed in terms of Ising superparamagnetism. From Kerr hysteresis loops, we deduce that the first anisotropy constant K1 in the superparamagnetic films is of order 0.345±0.020 MJ/m3.

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Magnetic Hardening In Fept Nanostructured Films, J. Ping Liu, Yi Liu, C.P. Luo, Z.S. Shan Apr 1997

Magnetic Hardening In Fept Nanostructured Films, J. Ping Liu, Yi Liu, C.P. Luo, Z.S. Shan

David Sellmyer Publications

FePt films have been prepared by sputtering Fe/Pt multilayers onto glass or silicon substrates. The thickness of the Fe and Pt layers was adjusted with the Fe:Pt atomic ratio from about 1:1 to 2:1. Magnetic hardening is observed after heat treatment at elevated temperatures, which led to coercivity values exceeding 20 kOe in samples with an Fe:Pt ratio around 1.2:1. The hardening originates from the formation of the tetragonal FePt phase with high magnetocrystalline anisotropy and a favorable microstructure. Two-phase composite films containing hard and soft phases were obtained when the Fe:Pt ratio increased. Under optimized processing conditions, composite films …

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Nanostructure And Magnetic Anisotropy Of Co/Au Multilayers, Yi Liu, Z.S. Shan, David J. Sellmyer Apr 1997

Nanostructure And Magnetic Anisotropy Of Co/Au Multilayers, Yi Liu, Z.S. Shan, David J. Sellmyer

David Sellmyer Publications

Multilayer Co/Au films were deposited on 40 nm Au underlayer by magnetron sputtering. The Co thickness is kept constant at 0.5 nm while the Au thickness is varied from 0.5 to 8 nm. Magnetic measurements show that the perpendicular anisotropy of the films changes from 3 × 106 to 1.5 × 106 erg/cm3 as the Au thickness changes from 6 to 1 nm. Two films of (Co 0.5 nm/Au 6 nm) × 9/Au 40 nm (denoted Au6) and (Co 0.5 nm/Au 1 nm) × 50/Au 40 nm (denoted Au1) were examined by transmission electron microscopy. For the …

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Magnetic Properties And Switching Volumes Of Nanocrystalline Smfesic Films, S.Y. Zhang, Z.S. Shan, Yi Liu, T.Y. Zhao, J.G. Zhao, B.G. Shen, W.S. Zhan, David J. Sellmyer Apr 1997

Magnetic Properties And Switching Volumes Of Nanocrystalline Smfesic Films, S.Y. Zhang, Z.S. Shan, Yi Liu, T.Y. Zhao, J.G. Zhao, B.G. Shen, W.S. Zhan, David J. Sellmyer

David Sellmyer Publications

Systematic studies of the effects of Si addition on the magnetic and magnetization reversal properties of SmFeSiC films are presented. The magnetic switching volume and other magnetic parameters (e.g., coercivity) are strongly dependent upon the Si content. Correlations between switching volume, coercivity, and the intergrain interactions are discussed.

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