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Structural Effects On K-Vacancy Production By Protons Of Extreme Relativistic Energies, P.T. Leung, M. L. Rustgi Nov 1982

Structural Effects On K-Vacancy Production By Protons Of Extreme Relativistic Energies, P.T. Leung, M. L. Rustgi

Physics Faculty Publications and Presentations

The effect on the K-vacancy-production cross section due to the finite distribution of charge and magnetic moment of the incident proton is examined. Numerical results are given for two target elements, namely, Ni and U. The results show that even at energy as high as 10³ GeV the incident proton can still be regarded as a point charge. The effect on the stopping power of matter is discussed.

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Magnetic And Crystallization Studies Of Splat-Cooled Praseodymium–Gallium–Iron Alloys, George C. Hadjipanayis, S.H. Woollins, R.C. Hazelton, K.R. Lawless, R. Prestipino, David J. Sellmyer Nov 1982

Magnetic And Crystallization Studies Of Splat-Cooled Praseodymium–Gallium–Iron Alloys, George C. Hadjipanayis, S.H. Woollins, R.C. Hazelton, K.R. Lawless, R. Prestipino, David J. Sellmyer

David Sellmyer Publications

Magnetic hysteresis and crytallization studies are reported for several (Pr80Ga20)100-xFex metallic glasses, where 30≤x≤80. Thermomagnetic data show the presence of two magnetic phases which are probably responsible for the relatively high coercive fields observed at cryogenic temperatures. As the iron content of the sample is increased, the magnetic moment increases substantially but the coercivity is drastically reduced. In (Pr80Ga20)70Fe30 the observed coercive fields are strongly temperature dependent indicating strong thermal activation effects which are consistent with the magnetic viscosity measurements. The hard magnetic properties disappear after …

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Magnetic Properties Of Hydrides Of Rare Earth–Transition Metal Glasses, C.G. Robbins, Z.D. Chen, J.G. Zhao, Michael J. O'Shea, David J. Sellmyer Nov 1982

Magnetic Properties Of Hydrides Of Rare Earth–Transition Metal Glasses, C.G. Robbins, Z.D. Chen, J.G. Zhao, Michael J. O'Shea, David J. Sellmyer

David Sellmyer Publications

The effect of hydrogen on magnetic properties of metallic glasses of the form (R80Ga20)1-xTxHy where R=Pr, Nd, Gd, Tb, Er; T=Cr, Fe, Co, B; 0≤x≤0.3 and 0≤y≤1.7 is reported. The anisotropic rare earth glasses without H all exhibit speromagnetic (spin-glass-like) transitions and the effect of hydrogen, in most cases, is to lower the peak in χac significantly but leave TC relatively unchanged. For the Gd glass with T=Fe and x=0.1 the introduction of H at the level y=0.55 causes a large decrease in TC and a significant increase …

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Electron Transport In Tb- And Pr-Based Metallic Glasses, S.G. Cornelison, David J. Sellmyer Nov 1982

Electron Transport In Tb- And Pr-Based Metallic Glasses, S.G. Cornelison, David J. Sellmyer

David Sellmyer Publications

Electrical resistivity measurements are reported on several metallic glasses based on Pr and Tb, and Ga and various transition metals as the glass formers. In general negative temperature coefficients were observed and these are discussed in terms of the extended Ziman theory and the tunneling or localization theory. Low temperature structure in the resistivity can be understood with the coherent exchange scattering model of Asomoza et al. Journal of Applied Physics is copyrighted by The American Institute of Physics.

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Resistivity And Galvanomagnetic Coefficients Of Iron Group Metallic Glasses With Chromium Substitutions, J.R. Long, George C. Hadjipanayis, David J. Sellmyer Nov 1982

Resistivity And Galvanomagnetic Coefficients Of Iron Group Metallic Glasses With Chromium Substitutions, J.R. Long, George C. Hadjipanayis, David J. Sellmyer

David Sellmyer Publications

Magnetic field and temperature dependences of the electrical resistivities and Hall resistivities were measured for the metallic glass ferromagnets Fe13Ni60Cr5Si10B12, Fe37Ni36Cr5Si10B12, Fe81B13.5Si3.5C2, and Fe5Co75Si15B5. Resistance minima and magnetoresistivity of the FeNiCr glasses have been found to be consistent with a modified Kondo model of low temperature scattering. The Hall resistivities are positive and large. The spontaneous Hall coefficients of the FeNiCr glasses are in …

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Amorphous FeXNb100-X With Wide Composition Range, C.L. Chien, K.M. Unruh, Sy_Hwang Liou Nov 1982

Amorphous FeXNb100-X With Wide Composition Range, C.L. Chien, K.M. Unruh, Sy_Hwang Liou

Sy-Hwang Liou Publications

Sputtered amorphous FexNb100-x (30 ≤ x ≤ 85) has been studied by Mössbauer spectroscopy and resistivity measurements. The samples with x< 60 are nonmagnetic. The magnetic ordering temperatures of the samples with x ≥ 60 increase with Fe content. Small magnetic hyperfine fields are observed in the magnetic samples, consistent with the small Fe moments measured. The resistivity of the magnetic and nonmagnetic samples show different temperature dependences. Only the magnetic samples exhibit a resistivity minimum, indicating a Kondo-like mechanism.

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Exotic Levels From Topology In The Quantum-Chromodynamic Effective Lagrangian, A. P. Balachandran, V. Parameswaran Nair, S. G. Rajeev, A. Stern Oct 1982

Exotic Levels From Topology In The Quantum-Chromodynamic Effective Lagrangian, A. P. Balachandran, V. Parameswaran Nair, S. G. Rajeev, A. Stern

Publications and Research

Skyrme has shown that the SU ⊗ SU(2) chiral model has nontrivial topological sectors with static solutions for suitable Lagrangians. The baryon number B and strangeness of these sectors have been studied, and the existence of bound states of the nucleon field to the lightest solitons is shown. It is found that there must be long-lived levels with |B|≳6 and |s|≳6 and 1.8 GeV≲m≲5.6 GeV, some having half-integral charge and exotic relation between B and s, that can be pair produced in, say, e+e− collisions.

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Effects On Electrolytic Cells Of Magnetic Fields Applied To Single Electrodes, Craig Allen Cousins Oct 1982

Effects On Electrolytic Cells Of Magnetic Fields Applied To Single Electrodes, Craig Allen Cousins

Dissertations and Theses

The primary goal of this research was to investigate the effects associated with the application of magnetic fields to single electrodes.

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Birefringence Determination Of Magnetic Moments Of Magnetotactic Bacteria, Charles Rosenblatt, F. F. Torres De Araujo, Richard B. Frankel Oct 1982

Birefringence Determination Of Magnetic Moments Of Magnetotactic Bacteria, Charles Rosenblatt, F. F. Torres De Araujo, Richard B. Frankel

Physics

A birefringence technique is used to determine the average magnetic moments of magnetotactic bacteria in culture. Differences in are noted between live and dead bacteria, as well as between normal density and high density samples of live bacteria.

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Explicit Determination Of The Complex Refractive Index Of An Absorbing Medium From Reflectance Measurements At And Near Normal Incidence, R. M.A. Azzam Oct 1982

Explicit Determination Of The Complex Refractive Index Of An Absorbing Medium From Reflectance Measurements At And Near Normal Incidence, R. M.A. Azzam

Electrical Engineering Faculty Publications

Measurement of reflectance at normal incidence R and its fractional change ΔR/R caused by a change of the angle of incidence from 0 to a small angle ϕ (ϕ≲ 20°) permits explicit determination of both the refractive index n and extinction coefficient k of an isotropic absorbing medium. The medium of incidence (ambient) is assumed to have a known refractive index (e.g., =1 for vacuum or air), and the incident light is either p or s linearly polarized.

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Theoretical Study Of The Long-Wavelength Optical Properties Of Nacl, Kcl, Kbr, And Ki, John R. Hardy, A. M. Karo Sep 1982

Theoretical Study Of The Long-Wavelength Optical Properties Of Nacl, Kcl, Kbr, And Ki, John R. Hardy, A. M. Karo

John R. Hardy Papers

We have made a detailed theoretical study of the long-wavelength absorption of NaCl, KCl, KBr, and KI, associated with two-phonon difference processes caused by third-order anharmonic terms in the lattice potential energy. It was found that a simple nearest neighbor approximation to the anharmonicity, combined with lattice-dynamical eigenfrequencies and eigenvectors generated with the use of a deformation dipole model, can generally account for most of the observed absorption. This agreement was obtained without the use of any disposable parameters, as the form of the first-neighbor potential was predetermined. It was also found that discrepancies between theory and experiment can generally …

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Physical Conditions In The Accretion Disk Of V603 Aquilae, Gary J. Ferland, D. L. Lambert, M. L. Mccall, G. A. Shields, M. Slovak Sep 1982

Physical Conditions In The Accretion Disk Of V603 Aquilae, Gary J. Ferland, D. L. Lambert, M. L. Mccall, G. A. Shields, M. Slovak

Physics and Astronomy Faculty Publications

Ultraviolet and optical spectra of the old nova V603 Aql are discussed. The UV-optical continuum is dominated by emission from the accretion disk. Emission lines from ions of H, He, C, N, and 0 are identified. These lines are probably formed in a circumstellar shell with radius comparable to the binary separation, density ~1010 cm-3, and a roughly solar chemical composition. This corona is probably heated by radiation emitted by the underlying accretion disk. Photoionization calculations of the structure and emission-line spectrum of the corona are presented, and the effects of this gas on the X-ray continuum …

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Polarization-Preserving Single-Layer-Coated Beam Displacers And Axicons, R. M.A. Azzam, M. Emdadur Rahman Khan Sep 1982

Polarization-Preserving Single-Layer-Coated Beam Displacers And Axicons, R. M.A. Azzam, M. Emdadur Rahman Khan

Electrical Engineering Faculty Publications

A design procedure is described to determine the thicknesses of single-layer coatings of a given dielectric on a given metallic substrate so that any input polarization of light is preserved after two reflections at the same angle of incidence from a parallel-mirror beam displacer or an axicon. This is achieved by equalizing the net complex p and s reflection coefficients (also called the radial and azimuthal eigenvalues of an axicon) after two reflections. The net polarization-independent reflectance (insertion loss) of the device is computed and found to exceed the net minimum parallel reflectance of the uncoated device for incidence above …

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Aspects Of Duality In Chiral Field Theories, A. P. Balachandran, V. Parameswaran Nair, B. S. Skagerstam, C. G. Trahern Sep 1982

Aspects Of Duality In Chiral Field Theories, A. P. Balachandran, V. Parameswaran Nair, B. S. Skagerstam, C. G. Trahern

Publications and Research

The Abelian and non-Abelian gauge potentials Auv are known to describe chiral fields. Here we study their interactions with dual extended objects. The region occupied by these objects is shown to behave like a distinct phase of chiral fields which is nondissipative under suitable geometric conditions. A method for the realization of the 't Hooft algebra in these systems is outlined. The concept of electric and magnetic duality in electromagnetism is generalized to chiral fields with values in a symmetric space.

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Selective Deposition Of Sio2 Thin Films In Acid Baths, M. A. Smith, L. L. Levenson Sep 1982

Selective Deposition Of Sio2 Thin Films In Acid Baths, M. A. Smith, L. L. Levenson

Physics Faculty Research & Creative Works

We report observation of deposition of SiO2 thin films on a variety of surfaces in nitric acid and hydrochloric acid solutions. Scanning electron microscopy shows that the films are composed of closely packed spheres 1000 Å in diameter. Chemical identification is made with Auger electron spectroscopy. The films are generally between 1000 and 2000 Å thick and are possibly hydrated. Deposition occurs in either acid for molarities in the 1-8 M range and at temperatures between 80 and 100 °C. The effects for molarities greater than 8 M and temperatures greater than 100 °C have not been investigated. Materials …

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Thresholds In Radiobiology, Robert Katz, Werner Hofmann Sep 1982

Thresholds In Radiobiology, Robert Katz, Werner Hofmann

Robert Katz Publications

Interpretations of radiation effects frequently call upon the word “threshold.” In this letter we wish to explore the meaning of this word, its relationship to the fundamental character of radiation effects, and to the question of perception. We make no distinction between “stochastic effects” and “non-stochastic effects” (ICRU 1971, ICRP 1977). As conceived here, all interactions of radiation with matter are probabilistic. At the cellular or molecular level, where most radiation effects originate, the statistical nature of ionization and excitation events gives rise to considerable fluctuation in the number of these primary events in sensitive sites. Whatever the array of …

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Elastic Scattering Of Protons From Hydrogen Atoms At Energies 15-200kev, J. M. Wadehra, Robin Shakeshaft Sep 1982

Elastic Scattering Of Protons From Hydrogen Atoms At Energies 15-200kev, J. M. Wadehra, Robin Shakeshaft

Physics and Astronomy Faculty Research Publications

Differential and integrated cross sections for the elastic process H^+ + H(1s) → H^+ + H(1s) were calculated with the use of results of coupled-state calculations in the energy range 15-200 keV. Results are presented and, at 60 keV, compared favorably with preliminary experimental data. The asymptotic form of the elastic amplitude for b≫a_0 (where b is the impact parameter) is derived for the two cases λ≪1 and λ≫1, where λ is the ratio of the collision duration to the orbital period. The asymptotic form for λ≫1 provides a useful test on the numerical accuracy of the amplitudes.

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Scheme To Polarization-Correct A Waxicon, R. M.A. Azzam Sep 1982

Scheme To Polarization-Correct A Waxicon, R. M.A. Azzam

Electrical Engineering Faculty Publications

No abstract provided.

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Stationary Property Of Normal-Incidence Reflection From Isotropic Surfaces, R. M.A. Azzam Sep 1982

Stationary Property Of Normal-Incidence Reflection From Isotropic Surfaces, R. M.A. Azzam

Electrical Engineering Faculty Publications

The complex reflection coefficients for the parallel (p) and perpendicular (s) polarizations of light that are normally incident upon an isotropic surface are proved to be stationary with respect to small changes of the angle of incidence in the neighborhood of zero. This is true not only for a single interface between isotropic media but also for any one-dimensionally inhomogeneous or multilayer reflecting structure that is stratified in the direction of the surface normal. For incident light of certain intensity, phase, and polarization, the intensity, phase, and polarization of the reflected light all remain stationary with …

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1981 Oersted Medal: I. I . Rabi And Melba Newell Phillips Award 1982, Robert Fuller Sep 1982

1981 Oersted Medal: I. I . Rabi And Melba Newell Phillips Award 1982, Robert Fuller

Robert G. Fuller Publications

This award is given for exceptional contributions to physics education through leadership in the American Association of Physics Teachers. The award will not be given annually, but occasionally to an outstanding physics educator.

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Temporary Negative Ions In The Chloromethanes Chcl2F And Ccl2F2: Characterization Of The Σ* Orbitals, Paul Burrow, A. Modelli, N.S. Chiu, K.D. Jordan Sep 1982

Temporary Negative Ions In The Chloromethanes Chcl2F And Ccl2F2: Characterization Of The Σ* Orbitals, Paul Burrow, A. Modelli, N.S. Chiu, K.D. Jordan

Paul Burrow Publications

The electron transmission spectra of chlorometers CHCl2F and CCl2F2 are presented. The electron affinities are evaluted compared with thoses calculated using self-consistent field methods.

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Monte Carlo Studies Of Water Monolayer Clusters On Substrates: Hexagonal Agi, Richard C. Ward, Jon M. Holdman, Barbara N. Hale Sep 1982

Monte Carlo Studies Of Water Monolayer Clusters On Substrates: Hexagonal Agi, Richard C. Ward, Jon M. Holdman, Barbara N. Hale

Physics Faculty Research & Creative Works

A Monte Carlo procedure is used to study the stability and structure of small water clusters adsorbed on model basal and prism faces of hexagonal AgI. Effective pair potentials for the H2O-AgI interaction [B. N. Hale and J. Kiefer, J. Chem. Phys. 73, 923 (1980)] and the revised central force potentials for the H2O-H2O interaction [F. H. Stillinger and A. Rahman, J. Chem. Phys. 68, 666 (1978)] are used to determine average internal cluster binding energy and average cluster-substrate binding energy for water clusters containing 6, 24, and 44 water molecules at temperatures 240, …

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Intermediate-Band Photometry In The Open Cluster Ngc 6664, Edward G. Schmidt Aug 1982

Intermediate-Band Photometry In The Open Cluster Ngc 6664, Edward G. Schmidt

Edward Schmidt Publications

Four-color and Hβ photometry is given for early-type stars in the open cluster NGC 6664. From these data the true distance modulus is found to be 10.7 and the reddening is found to range from E (b – y) = 0.48 to 0.63 across the cluster. The distance modulus agrees well with some values from the literature, but the present color excesses are about 0.1 mag larger than published values. There are two or perhaps three blue stragglers in the cluster and its age is estimated to be 46 × 106 yr.

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Study Of Lattice Instabilities In Snx Euy-X Mo6s8 (Y=1.0 And 1.2), Paul D. Hambourger, J. C. Ho, C. Y. Huang, H. L. Luo Aug 1982

Study Of Lattice Instabilities In Snx Euy-X Mo6s8 (Y=1.0 And 1.2), Paul D. Hambourger, J. C. Ho, C. Y. Huang, H. L. Luo

Physics Faculty Publications

An anomaly in the heat capacity of Eu1.2Mo6S8 at ∼120 K (T0) has been observed and identified as a structural transformation. The heat capacity, electrical resistance, and Hall coefficient for the Eu-rich pseudoternaries have been measured under pressure to obtain the pressure dependence of T0. The depression of T0 by pressure is used to explain the pressure dependence of the superconducting transition temperature and the anomalous temperature dependence of the critical field.

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24th Rocky Mountain Conference Aug 1982

24th Rocky Mountain Conference

Rocky Mountain Conference on Magnetic Resonance

Abstracts and meeting program from the 24th annual meeting of the Rocky Mountain Conference, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, August 1-5, 1982.

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Modeling Charge Diffusion From Proton-Induced Ionization Tracks In Silicon Photodiode Arrays, Lee Cole Smith Aug 1982

Modeling Charge Diffusion From Proton-Induced Ionization Tracks In Silicon Photodiode Arrays, Lee Cole Smith

Physics Theses & Dissertations

We are modeling the combined problem of generation and collection of charge carriers created during passage of energetic protons through a silicon photodiode array. We have also experimentally obtained pulse-height distributions of noise charge collected during exposure of a Digicon-type diode array to 21 and 75 MeV protons. It is shown that the magnitude of charge collected by a diode from each proton event is determined not only by diffusion, but by statistical considerations involving the ionization process itself. Utilizing analytical solutions to the diffusion equation for transport of minority carriers, together with the Vavilov-Landau theory of energy-loss fluctuations in …

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New Perspectives On Electron Correlations, Anthony F. Starace Aug 1982

New Perspectives On Electron Correlations, Anthony F. Starace

Anthony F. Starace Publications

Two formulations for describing electronic excitations developed by Fano and his school are reviewed. The transition matrix formulation of atomic photoionization has provided new perspectives on the well-known random phase approximation and on its relation to configuration interaction. The hyperspherical coordinate approach to two electron states and collision processes has provided new perspectives on the classification of two-electron excitation channels and on the evolution of highly excited electronic states.

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Biological Effects Of Low Doses Of Ionizing Radiations: Particle Tracks In Radiobiology, Robert Katz, Werner Hofmann Jun 1982

Biological Effects Of Low Doses Of Ionizing Radiations: Particle Tracks In Radiobiology, Robert Katz, Werner Hofmann

Robert Katz Publications

A radiation field is made up of a tangle of particle tracks, from the primary particle and secondary and higher generation electron interactions, well isolated at low doses and with multiple intersections in cell nuclei at high doses. Low dose effects in multicellular systems are therefore the sum of individual track structures. Until we can state with confidence the structure of a particle track in biological matter for all end-points of interest, at least as well as we can for nuclear emulsions, our knowledge of low dose effects should be regarded as uncertain and inadequate. In this context “track structure” …

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Measurement Of Spin-Exchange Effects In Electron-Hydrogen Collisions: 90° Elastic Scattering From 4 To 30 Ev, G. D. Fletcher, M. J. Alguard, Timothy J. Gay, V. W. Hughes, C. W. Tu, P. F. Wainwright, M. S. Lubell, W. Raith, F. C. Tang Jun 1982

Measurement Of Spin-Exchange Effects In Electron-Hydrogen Collisions: 90° Elastic Scattering From 4 To 30 Ev, G. D. Fletcher, M. J. Alguard, Timothy J. Gay, V. W. Hughes, C. W. Tu, P. F. Wainwright, M. S. Lubell, W. Raith, F. C. Tang

Timothy J. Gay Publications

With use of a Fano-effect polarized electron source and a state-selected thermally dissociated hydrogen beam, the interference between the direct and the exchange scattering amplitudes was measured for 90° elastic scattering of electrons from atomic hydrogen for energies between 4 and 30 eV.

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Absorption Coefficients Of Ozone At Low Temperature In The Visible Region, Hessameddin Ghiassi Jun 1982

Absorption Coefficients Of Ozone At Low Temperature In The Visible Region, Hessameddin Ghiassi

Physics Theses & Dissertations

The temperature dependence of absorption coefficients of ozone was studied between 7567 Å and 4630 Å . When the gas was cooled from room temperature to -108° C, an overall increase in the absorption coefficients was noticed. The maximum increase of 5% occurred at λ = 6020 Å. In general, the absorption is linearly dependent on temperature.

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