Physical Sciences and Mathematics Commons^™

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 …

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 …

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 A_uv 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.

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 …

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 …

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 …

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.

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

Electrical Engineering Faculty Publications

No abstract provided.

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 …

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.

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.

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, …

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.

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 Eu_1.2Mo₆S₈ 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.

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.

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.

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 …

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.

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” …

In-Situ Measurements Ofwave Electric Fields In The Equatorial Electrojet, R. C. Pfaff, M. C. Kelley, Bela G. Fejer, N. C. Maynard, K. D. Baker

Bela G. Fejer

Electric field wave measurements have been performed on two sounding rockets in the equatorial ionosphere. During a daytime flight from Chilca, Peru, intense electrostatic waves were detected on the upward directed electron density gradient. During a nighttime flight from Kwajalein Atoll, similar waves were detected on a downward directed gradient. These results are in agreement with a gradient drift instability explanation of the generation of the waves. The wave amplitudes were as high as 5 mV/m implying perturbation drifts comparable to the driving drift velocities. Power spectra from the turbulent region show a peak at long wavelengths, followed by a …

Long Wavelength Irregularities In The Equatorial Electrojet, E. Kudeki, D. T. Farley, Bela G. Fejer

Bela G. Fejer

We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach or exceed the ion-acoustic velocity even though the horizontal phase velocity of the wave is considerably smaller. A straightforward extension to the long wavelength regime of the usual linear …

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.

Nonperturbative Proof Of The Non-Abelian Anomalies, A. P. Balachandran, G. Marmo, V. P. Nair, C. G. Trahern

Publications and Research

We give a nonperturbative derivation of non-Abelian anomalies.

Theoretical And Experimental Optical Holography, Warren A. Krueger

Senior Scholar Papers

The intent of this paper is to present an analysis of optical holography. Both the physical theory behind holography and the experimental techniques used in making holograms will be presented. To accomplish this goal, the paper is divided into two independent sections: the theoretical section followed by the experimental section. Each section is intended to be a complete unit. The Theoretical Section is an exposure to the theory behind holography. This consists of a review of the concepts of interference and diffraction. followed by a brief review of partial coherence. The remaining part of the Theoretical Section is devoted to …

Brewster And Pseudo-Brewster Angles Of Uniaxial Crystal Surfaces And Their Use For Determination Of Optical Properties, M. Elshazly-Zaghloul, R. M.A. Azzam

Electrical Engineering Faculty Publications

Brewster and pseudo-Brewster angles are defined for surfaces of transparent and absorbing uniaxial crystals parallel and perpendicular to the optic axis. Two Brewster angles of a transparent uniaxial crystal surface parallel to the optic axis, measured when the optic axis is oriented perpendicular and parallel to the plane of incidence, readily determine the ordinary and extraordinary indices N_o and N_e. N_o and N_e can also be obtained from two Brewster angles measured on a surface perpendicular to the optic axis in contact with two media of different refractive indices. Conditions for the existence of two …

Simple Vibrating Sample Magnetometer, J.A. Gerber, W.L. Burmester, David J. Sellmyer

David Sellmyer Publications

Design features of a simple and relatively inexpensive homemade vibrating sample magnetometer are described. These include signal electronics which employs an analog divider rather than the usual electromechanical feedback circuit, and a method for gas cleaning during sample changes allowing long experiments at liquid helium temperatures in a superconducting solenoid. Review of Scientific Instruments is copyrighted by The American Institute of Physics.

Massless Neutrinos And The Stellar Stopping Power Via The V-A And Weinberg Interactions, P.T. Leung, M. L. Rustgi

Physics Faculty Publications and Presentations

A formula for the stopping power of matter for neutrinos and antineutrinos, interacting with electrons via the weak interaction in the context of both the V-A theory and the Weinberg theory is derived in the high-Q approximation and applied to study the solar-neutrino anomaly. The result shows that neutrinos extending in energy from 1 to 10 MeV produced inside the Sun escape it essentially without any loss of energy. In agreement with previous investigators, Rustgi, Leung, Turner, and Brandt (1981). It is found that the neutrinos should retain the energy given them at their creation essentially forever and permeate the …

On The Transport Equations For Anisotropic Plasmas, Abdallah R. Barakat

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

First, I attempt to present a unified approach to the study of transport phenomena in multicoponent anisotropic space plasmas. In the limit of small temperature anisotropies this system of generalized transport equations reduces to Grad's 13-moment system of transport equations. In the collisionless limit, the generalized transport equations account for collisionless heat flow, collisionless viscosity, and large temperature anisotropies. Also, I show that with the appropriate assumptions, the system of generalized transport equations reduces to all of the other major systems of transport equations for anisotropic plasmas that have been derived to date.

Next, for application to aeronomy and space …

Electro-Optics Applications For Alleviating Emi/Emc/Emp Problems, George H. Baker, Walter H. Hardwick

George H Baker

No abstract provided.

Reaction ⁶Li(P, Δ⁺⁺)⁶He At 1.04 Gev And The Δ−N Interaction, T. Hennino, D. Bachelier, Oleksa-Myron Bilaniuk, J. L. Boyard, J. C. Jourdain, M. Roy-Stephen, P. Radvanyi, M. Bedjidian, E. Descroix, P. Foessel, S. Gardien, J. Y. Grossiord, A. Guichard, M. Gusakow, R. Haroutunian, M. Jacquin, J. R. Pizzi, A. Garin

Physics & Astronomy Faculty Works

The reaction ⁶Li(p, Δ⁺⁺)⁶He has been studied at 1.04 GeV for transferred momenta ranging from 0.11 to 0.35 (GeV/c)2. An exponential decrease of the cross section is observed. A Glauber-type calculation is presented. The possibility of extracting information on σ(ΔN) and α(ΔN) is discussed.