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Electron Drift Velocities In Helium-Fluorine Gas Mixtures, Kaare J. Nygaard, John L. Fletcher, Scott R. Hunter, Stephen R. Foltyn May 1978

Electron Drift Velocities In Helium-Fluorine Gas Mixtures, Kaare J. Nygaard, John L. Fletcher, Scott R. Hunter, Stephen R. Foltyn

Physics Faculty Research & Creative Works

Using a simple time-of-flight technique, we have measured the electron drift velocity in helium with 0.1-1% fluorine additive. Our results in a 0.1% mixture are in close agreement with data in pure helium. The measured drift velocity increases with increasing fluorine concentration. © 1978, American Institute of Physics. All rights reserved.

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Energy And Angular Distribution Of Neutrons From Proton-Proton Inelastic Scattering At 800 Mev, Ted Dean Rupp Apr 1978

Energy And Angular Distribution Of Neutrons From Proton-Proton Inelastic Scattering At 800 Mev, Ted Dean Rupp

Physics & Astronomy ETDs

The neutron energy spectra from the reaction p + p → n + p + π+ for an incident proton energy of 800 MeV was measured for all phase space. ++ The channels were dominated by △++. (1232) resonance and had a total cross section of 16 ± 1.5 mb. Also, the data demonstrated the dominance of Sand P waves. The experimental results were compared to isobar, phase space and a one pion exchange model. The isobar and phase space models failed to predict the experimental results; however, the one pion exchange model fit the data for …

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Polynomial And Rational Fraction Representations Of A Diatomic Molecular Potential, Paul R. Findley Apr 1978

Polynomial And Rational Fraction Representations Of A Diatomic Molecular Potential, Paul R. Findley

Physics & Astronomy ETDs

A method is presented for approximating a diatomic molecular vibrational potential by fitting to modified forms of the potential. Power's numerical Born-Oppenheimer potential for the H2+ electronic ground state is the potential used in this thesis. The modification procedure is to multiply the potential by various powers of the internuclear separation. This removes the troublesome Coulomb pole at zero internuclear separation. Graphs of the modified forms are presented. Polynomials were fitted directly to the potential, to the modified forms, and to the pure electronic energy. Comparisons are made among the various representations of the potential obtained from the …

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Theoretical Thermodynamic Functions For Krypton Gas, A-Hamid Aidinejad Apr 1978

Theoretical Thermodynamic Functions For Krypton Gas, A-Hamid Aidinejad

Masters Theses

No abstract provided.

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Generalization Of The Form Of The T Matrix Operator Of Non-Relativistic Scattering Theory, Francis Leone Apr 1978

Generalization Of The Form Of The T Matrix Operator Of Non-Relativistic Scattering Theory, Francis Leone

Masters Theses

No abstract provided.

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Simulation Of Mechanical Rotation By Optical Rotation: Application To The Design Of A New Fourier Photopolarimeter, R. M.A. Azzam Apr 1978

Simulation Of Mechanical Rotation By Optical Rotation: Application To The Design Of A New Fourier Photopolarimeter, R. M.A. Azzam

Electrical Engineering Faculty Publications

The mechanical rotation of an optical element around the axis of a beam of polarized light can be easily simulated by using the phenomenon of optical rotation. Because optical rotation can be magnetically or electrically induced, virtually any kind of mechanical rotation can be mimicked. This interesting principle is applied to the design of a new Fourier photopolarimeter that uses an oscillating-azimuth retarder (OAR). The OAR consists of a quarter-wave plate surrounded by two ac-excited Faraday cells that produce equal and opposite sinusoidal optical rotations. Analysis of the operation of this polarimeter of no moving parts proves its ability to …

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Generalized Ellipsometry Based On Azimuth Measurements Alone, R. M.A. Azzam Apr 1978

Generalized Ellipsometry Based On Azimuth Measurements Alone, R. M.A. Azzam

Electrical Engineering Faculty Publications

We investigate the azimuth response function, θo = f(θi), of a linear nondepolarizing optical system S, whereθi and θo, are the azimuths (orientations) of the generally elliptic vibrations of totally polarized light at the input and output of S. We find that the azimuth response function depends on five of the six parameters that specify the normalized circular Jones matrix of the optical system. Thus the entire polarization response of an optical system can be nearly completely reconstructed from its azimuth response alone. Five input-output azimuth measurements (θik, θok), k …

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Tip-Angle-Dependent Magnetic Relaxation In Superfluid 3he, Richard A. Webb Mar 1978

Tip-Angle-Dependent Magnetic Relaxation In Superfluid 3he, Richard A. Webb

Faculty Publications

Using a pulsed superconducting-quantum-interference-device (SQUID) NMR technique, relaxation of the longitudinal magnetization in superfluid 3He has been measured in magnetic fields of 31, 102, 180, and 306 Oe in the pressure range 16-26 bar. It is observed that in both superfluid phases there is a temperature-dependent, well-defined spin-tipping angle, θc, for which the relaxation of the magnetization changes from an exponential to a nonexponential behavior.

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Isospin Forbidden And Allowed Reactions 16O(Α,Α0)160 And 160(Α,Γ)20Ne, Daniel J. Steck Mar 1978

Isospin Forbidden And Allowed Reactions 16O(Α,Α0)160 And 160(Α,Γ)20Ne, Daniel J. Steck

Physics Faculty Publications

Six 20Ne levels have been investigated in detail via the 16O+α channel between 6.9≤Eα≤10.2 MeV. Level parameters for states at Ex(20Ne)=10.264±0.008, 11.077±0.008, 11.259±0.008, 11.552±0.008,12.237±0.008, and 12.390±0.008 MeV have been extracted from γ decay properties and phase shift analysis of the elastic scattering. With the exception of the 11.552 and 12.39 MeV states, these levels display primarily TT=0 states, several other weak γ decaying resonances were observed at 11.97 ± 0.04, 12.05 ± 0.04, and 12.49 ± 0.02 MeV but were not studied in detail. Charge dependent matrix elements (4-120 …

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Magnetic Properties Of The Rare-Earth Intermetallics RGa2, T.H. Tsai, J.A. Gerber, John W. Weymouth, David J. Sellmyer Mar 1978

Magnetic Properties Of The Rare-Earth Intermetallics RGa2, T.H. Tsai, J.A. Gerber, John W. Weymouth, David J. Sellmyer

David Sellmyer Publications

The magnetic susceptibility (χ) of polycrystalline samples of RGa2, R=Ce, Pr, Nd, Gd, Tb, Dy, Ho, and Er, has been measured at low field, from 1.5 K to 300 K. The magnetization of these samples also has been measured up to 80 kOe at low temperatures. Antiferromagnetic behavior was observed for all the samples with Neel temperatures (TN) ranging from about 4.1 K for CeGa2 to about 14.8 K for TbGa2. Curie-Weiss fits to the high-temperature χ (T) data led to effective moments in good agreement with those expected for …

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Magnetic Ordering In Amorphous Nd-Co, Gd-Co And Er-Co Alloys, J.A. Gerber, D.J. Miller, David J. Sellmyer Mar 1978

Magnetic Ordering In Amorphous Nd-Co, Gd-Co And Er-Co Alloys, J.A. Gerber, D.J. Miller, David J. Sellmyer

David Sellmyer Publications

Previous studies of magnetism in amorphous rare earth–transition metal alloys have emphasized alloys rich in transition metal. We report here results on three rare earth rich amorphous alloys: Nd64Co36, Gd65Co35, and Er65Co35. Low field susceptibility, χ, was measured for T in the range 4.2 K≤T≤300 K and magnetization was measured for 1.3≤T≤200 K and applied fields, H, of 0≤H≤80 kOe. Curie-Weiss fits were made to high temperature χ (T) data to determine average effective moments and Weiss temperatures. Hysteresis …

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Magnetic Ordering And Local Random Anisotropy In Dilute Magnetic Glasses, G.R. Gruzalski, J.D. Patterson, David J. Sellmyer Mar 1978

Magnetic Ordering And Local Random Anisotropy In Dilute Magnetic Glasses, G.R. Gruzalski, J.D. Patterson, David J. Sellmyer

David Sellmyer Publications

Magnetic susceptibility and high-field magnetization measurements are presented for amorphous Zr40Cu60-xMx (M denoting Fe, Mn, Gd, and Tb) and Nb50Ni50-xFex, with x ranging from zero to about ten. The alloys for M=Gd, Tb, and Fe develop low-temperature ordered states that are characterized as spin glass like, whereas the Mn alloy exhibits no evidence of order down to 1.3 K. The magnetic properties of these alloys are discussed in terms of local random anisotropy, fluctuations in the interimpurity exchange interactions, extremely short electron-mean-free paths, antiferromagnetic interactions between the …

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Ferromagnetic And Spin-Glass Ordering In Fe-Doped AuXPd1-X Alloys, E.R. Domb, David J. Sellmyer, T.M. Quick, R.J. Borg Mar 1978

Ferromagnetic And Spin-Glass Ordering In Fe-Doped AuXPd1-X Alloys, E.R. Domb, David J. Sellmyer, T.M. Quick, R.J. Borg

David Sellmyer Publications

Ferromagnetic and spin-glass ordering has been studied in (AuxPd1-x)1-cFec alloys for 0<~x<~1 and 0<~c≲0.06. Magnetic susceptibility, high-field magnetization, and Mössbauer measurements have been performed between liquid-helium and room temperature. For small x, the alloys are strongly exchange enhanced. Assuming that the local-moment-conduction-electron exchange coupling J is independent of x, and employing the Takahashi-Shimizu-Doniach-Wohlfarth theory, we obtain J=0.12 eV from the saturation moment versus host susceptibility data. The theory, however, fails to describe the interimpurity coupling that leads to magnetic order in the Pd-rich alloys. A simple phenomenological model, based on the ferromagnetic coupling of all the giant polarization clouds except those that are "isolated," gives qualitative agreement with the …

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Mössbauer Spectroscopy Of Iron Deposits In Thalassemic Heart Tissue, G. C. Papaefthymiou, K. S. Kaufman, Richard B. Frankel, A. Rosenthal Mar 1978

Mössbauer Spectroscopy Of Iron Deposits In Thalassemic Heart Tissue, G. C. Papaefthymiou, K. S. Kaufman, Richard B. Frankel, A. Rosenthal

Physics

No abstract provided.

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The Stephen F. Austin Traveling Science Show, James C. Dennis Jan 1978

The Stephen F. Austin Traveling Science Show, James C. Dennis

Faculty Publications

No abstract provided.

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Calculations Of Ion‐Ion Recombination Rates At High Pressures, J. M. Wadehra, J. N. Bardsley Jan 1978

Calculations Of Ion‐Ion Recombination Rates At High Pressures, J. M. Wadehra, J. N. Bardsley

Physics and Astronomy Faculty Research Publications

The classical theory of ion‐ion recombination in gases of high density is extended to allow for arbitrary ratios of the masses of the three species involved. Calculations are performed for the recombination of Ar+, Ar+ 2, Kr+, and Kr+ 2 ions with F− and of Hg+ and Ar+ with Cl− in an argon gas. The effective two‐body rates peak between 2×10−6 and 3×10−6 cm3 sec−1 at pressures above 1 atm.

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Evolved Contact Systems Of Spectral Type A: Au Puppis, V535 Arae, And V1073 Cygni, Kam-Ching Leung, Donald P. Schneider Jan 1978

Evolved Contact Systems Of Spectral Type A: Au Puppis, V535 Arae, And V1073 Cygni, Kam-Ching Leung, Donald P. Schneider

Department of Physics and Astronomy: Faculty Publications

The photoelectric observations of AU Pup, V535 Ara, and V1073 Cyg were reanalyzed with Wilson and Devinney's approach. All three systems are found to be contact configurations. AU Pup has an unusually large degree of overcontact, 72%. V1073 Cyg is found to be an evolved contact system since the radius of the primary is twice that of a zero-age main-sequence star of corresponding mass. All three systems are found to be evolved according to their locations in the period-spectral-type diagram. Improved photometric parameters are reported for all three systems.

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Plasma Lines In The Auroral E Layer, Vincent B. Wickwar Jan 1978

Plasma Lines In The Auroral E Layer, Vincent B. Wickwar

All Physics Faculty Publications

The first successful measurements of plasma lines in the auroral E layer were made in January 1976 using the Chatanika incoherent scatter radar. Although they are considerably weaker than the signal from the ion component, the plasma line signals are readily detectable. Typical signal-to-noise ratios were about 4%. In this series of experiments, plasma lines were observed in the interval between 3.8 and 6.0 MHz, which corresponds to phase energies between 0.55 and 1.4 eV. They were found between 98 and 134 km; the derived plasma wave intensities varied between 0.06 and 1.0 eV, and the enhancements between 4 and …

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Absolute Doubly Differential Cross Sections For Ejection Of Secondary Electrons From Gases By Electron Impact. Ii. 100-500-Ev Electrons On Neon, Argon, Molecular Hydrogen, And Molecular Nitrogen, R. D. Dubois, M. Eugene Rudd Jan 1978

Absolute Doubly Differential Cross Sections For Ejection Of Secondary Electrons From Gases By Electron Impact. Ii. 100-500-Ev Electrons On Neon, Argon, Molecular Hydrogen, And Molecular Nitrogen, R. D. Dubois, M. Eugene Rudd

M. Eugene Rudd Publications

Absolute doubly differential cross sections for secondary electron production by electron impact have been measured for static gas targets of neon, argon, hydrogen, and nitrogen. Electron impact energies were from 100 to 500 eV. An electrostatic analyzer was used to analyze secondary electrons with energies between 4 eV and the primary electron energy minus the first ionization potential of the target. Angles of emission were 10° to 150°. The present data agree well with the data of Opal, Beaty, and Peterson at 90° but, as was observed previously for helium, the agreement becomes increasingly poorer for larger and smaller angles. …

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Magnetoresistance Of 1t-Tase2, Paul D. Hambourger, F. J. Disalvo Jan 1978

Magnetoresistance Of 1t-Tase2, Paul D. Hambourger, F. J. Disalvo

Physics Faculty Publications

No abstract provided.

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Time Lag In Diffusion-Controlled Nucleation, David Peak Jan 1978

Time Lag In Diffusion-Controlled Nucleation, David Peak

All Physics Faculty Publications

Nucleation occurring in the presence of a dense solvent is accompanied by spatial correlations among the reactant clusters and monomers which affect the aggregation rates. The classical theory of nucleation, which does not take such correlations into account, overestimates the observed nucleation rate and underestimates the time lag in condensed systems. An explicit expression for the time lag in diffusion‐controlled nucleation is derived. Values associated with miscibility gap experiments differ from the classical predictions by factors of 5 to 10.

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Photoelectron Flux Build-Up In The Plasmasphere, G P. Mantas, Herbert C. Carlson, Vincent B. Wickwar Jan 1978

Photoelectron Flux Build-Up In The Plasmasphere, G P. Mantas, Herbert C. Carlson, Vincent B. Wickwar

All Physics Faculty Publications

Processes which confine photoelectrons to the plasmasphere (e.g., collisional backscattering from the thermosphere and magnetic trapping due to pitch angle redistribution through Coulomb collisions in the plasmasphere) tend to increase the steady state photoelectron flux in the plasmasphere above the amplitude level that would otherwise have been attained. Theoretical calculations are presented of steady state photoelectron fluxes in the plasmasphere, for specified atmospheric and ionospheric conditions. (Observational plasma line intensity data for these conditions exist and will be compared elsewhere.) General features of the angular distribution are presented and compared with observations. The transparency of the plasmasphere and the backscattering …

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Interpretation Emphasis In Exploration Geophysics, Paul J. Wolfe, Benjamin H. Richard Jan 1978

Interpretation Emphasis In Exploration Geophysics, Paul J. Wolfe, Benjamin H. Richard

Physics Faculty Publications

No abstract provided.

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Design And Construction Of An Inexpensive Anechoic Chamber, Charles E. Hughes Jr. Jan 1978

Design And Construction Of An Inexpensive Anechoic Chamber, Charles E. Hughes Jr.

Journal of the Arkansas Academy of Science

No abstract provided.

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On The Classical‐Spin Model Of Amorphous Ferromagnets, Harry A. Brown Jan 1978

On The Classical‐Spin Model Of Amorphous Ferromagnets, Harry A. Brown

Physics Faculty Research & Creative Works

No abstract provided.

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The Bethe‐Peierls‐Weiss Approximation For Amorphous Magnets, Harry A. Brown Jan 1978

The Bethe‐Peierls‐Weiss Approximation For Amorphous Magnets, Harry A. Brown

Physics Faculty Research & Creative Works

No abstract provided.

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Spin Correlations In Actinide Materials: A Neutron Study Of Usb, G. H. Lander, S. K. Sinha, Don M. Sparlin, O. Vogt Jan 1978

Spin Correlations In Actinide Materials: A Neutron Study Of Usb, G. H. Lander, S. K. Sinha, Don M. Sparlin, O. Vogt

Physics Faculty Research & Creative Works

Measurements have been made of the short-range spin correlations in USb, a metallic compound that orders antiferromagnetically. The system has no transverse fluctuations, and the longitudinal spin correlations are anisotropic, showing stronger interactions within the ferromagnetic sheets than between them. The results of this and other experiments can be understood with simple concepts involving the bonding of 5f electrons. © 1978 The American Physical Society.

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Production Of Cl⁻·Hcl Cluster Ions In Hcl-N2 Mixtures, R. J. Corbin, Kaare J. Nygaard, William R. Snow, Laird D. Schearer Jan 1978

Production Of Cl⁻·Hcl Cluster Ions In Hcl-N2 Mixtures, R. J. Corbin, Kaare J. Nygaard, William R. Snow, Laird D. Schearer

Physics Faculty Research & Creative Works

A drift-tube-mass-spectrometer apparatus has been used to study the production of Cl-·HCl cluster molecules in HCl-N2 mixtures. The concentration of HCl was 730 ppm and the total pressure ranged from 0.1-5 Torr. The primary ion Cl- is produced mainly by dissociative attachment of HCl and is converted to a cluster ion in a three-body collision. The rate of formation of the cluster ion is k2≃ 10-25 cm6/sec at E/N=12 Td. © 1978 American Institute of Physics.

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Proton Spin-Lattice Relaxation And Methyl Group Rotation, Peter A. Beckmann, C. I. Ratcliffe, B. A. Dunell Jan 1978

Proton Spin-Lattice Relaxation And Methyl Group Rotation, Peter A. Beckmann, C. I. Ratcliffe, B. A. Dunell

Physics Faculty Research and Scholarship

Proton spin-lattice relaxation times have been measured at 16, 31, and 59 MHz in 4-methyl-2,6-ditertiarybutyl phenol between 80 K and its melting point, 340 K. The variation of T1 with temperature shows too distinct minima. The lower-temperature minimum has been analyzed in terms of relaxation by reorientation of four of the six t-butyl methyl groups with an average apparent activation energy of about 2.4 kcal mole−1 (104 meV molecule−1). The higher-temperature minimum has been analyzed in terms of relaxation by reorientation of the t-butyl groups about their C3 axes with four of the six t-butyl methyl groups reorienting …

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Electron Spin Relaxation And Tunnelling Methyl Groups, Peter A. Beckmann, S. Clough Jan 1978

Electron Spin Relaxation And Tunnelling Methyl Groups, Peter A. Beckmann, S. Clough

Physics Faculty Research and Scholarship

The energy transfer has been studied between free radicals and nearby tunnelling methyl groups near the resonant condition that the electron Larmor frequency and the methyl tunnelling frequency are equal. The measurements were made in a gamma -irradiated single crystal of 4-methyl-2,6-ditertiarybutylphenol (MDBP) at 4.2K and consisted of saturating the ESR signal and observing its return to equilibrium. This has been done at eleven ESR frequencies in the range 8.97< nu s<0.63 GHz and for saturation times of 5, 50 and 200 s. A theoretical model has been developed for the non-exponential recovery which assumes that all the 4-methyl groups of the molecules surrounding a free radical have the same tunnelling rotation frequency nu t and that the only coupling between the electrons and the methyl groups is the intermolecular dipole-dipole interaction.

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