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1983

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Articles 1 - 30 of 123

Full-Text Articles in Physics

Pseudo-Brewster And Second-Brewster Angles Of An Absorbing Substrate Coated By A Transparent Thin Film, R. M.A. Azzam, T F. Thonn Dec 1983

Pseudo-Brewster And Second-Brewster Angles Of An Absorbing Substrate Coated By A Transparent Thin Film, R. M.A. Azzam, T F. Thonn

Electrical Engineering Faculty Publications

The pseudo-Brewster angle of minimum reflectance for the p polarization, the corresponding angle for thes polarization, and the second-Brewster angle of minimum ratio of the p and s reflectances are all determined as functions of the thickness of a transparent film coating an absorbing substrate by numerical solution of the exact equations that govern such angles of the form Re(Z′/Z) = 0, where Z = Rp, Rs, or ρ represent the complex amplitude-reflection coefficients for the p and s polarizations and their ratio (ρ =Rp/Rs), …

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Magnetic Phase Transition, Aggregate Formation, And Electrical Conductivity In Fecl3-Doped Polyacetylene, E. K. Sichel, M. F. Rubner, J. Georger, Jr., G. C. Papaefthymiou, S. Offer, Richard B. Frankel Dec 1983

Magnetic Phase Transition, Aggregate Formation, And Electrical Conductivity In Fecl3-Doped Polyacetylene, E. K. Sichel, M. F. Rubner, J. Georger, Jr., G. C. Papaefthymiou, S. Offer, Richard B. Frankel

Physics

Both Fe3+ and Fe2+ ions occur in FeCl3-doped polyacetylene. At low dopant levels (2+ and Fe3+ ions are paramagnetic down to 4.2 K. At dopant levels >0.01 mole fraction, there is evidence from Mössbauer spectroscopy that Fe2+ ions associate into aggregates which are magnetically ordered below 25 K. Aggregate formation appears to correlate with high electrical conductivity.

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Low-Mass Solitons From Fractional Charges In Quantum Chromodynamics, A. P. Balachandran, V. Parameswaran Nair, N. Panchapakesan, S. G. Rajeev Dec 1983

Low-Mass Solitons From Fractional Charges In Quantum Chromodynamics, A. P. Balachandran, V. Parameswaran Nair, N. Panchapakesan, S. G. Rajeev

Publications and Research

Slansky, Goldman, and Shaw have proposed a model to account for the observation of fractionally charged states. We show that in this model, there are expected to be several low-mass solitons (four being in the mass range ∼20-60 MeV) associated with the third homotopy group π3(SU(3)/SO(3))=Z4, besides a low-mass (∼30 MeV) Z2 monopole. Confirmation of these levels and hence of the model has important implications for Cabrera's results on the magnetic monopole. An efficient algorithm for the calculation of π3(G/H) for a general Lie group G and a subgroup H is developed. It is pointed …

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Two- And Three-Body Electron-Ion Recombination In Carbon Dioxide, Ian M. Littlewood, M. C. Cornell, B. K. Clark, Kaare J. Nygaard Dec 1983

Two- And Three-Body Electron-Ion Recombination In Carbon Dioxide, Ian M. Littlewood, M. C. Cornell, B. K. Clark, Kaare J. Nygaard

Physics Faculty Research & Creative Works

The electron-ion recombination rate in carbon dioxide was measured as a function of electric field strength and gas pressure. The separate effects of two- and three-body recombination was observed, and the respective rate constants obtained. The results indicate that three-body recombination is dominant at low field strengths for gas pressures above 1 atm, whereas two-body recombination is dominant at high field strengths.

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Non-Equilibrium L-Shell Effects On K-Shell X Rays For 20-54 Mev S+C Collisions, Donald Solon Shippy Dec 1983

Non-Equilibrium L-Shell Effects On K-Shell X Rays For 20-54 Mev S+C Collisions, Donald Solon Shippy

Masters Theses

Projectile K x-ray yields have been measured as a function of target thickness (2.0-150 μg/ cm2) for 20-54 MeV Sq+ ions incident on this carbon foils using the WMU EN tandem Van de Graaff accelerator. The measured K x-ray yields were fond to increase for thicknesses < 15 μg/cm2 and decease for thicknesses > 15 μg/cm2 . The increasing yield is attributed to L-Shell non-equilibrium as the ion traverses the foil, while the decreasing yield is attributed to K-shell non-equilibrium. Analysis of the data was performed by modifying the "two-component" model of Betz et al. to include the effect of …

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Cross Sections For Ionizaton Of Gases By 5-4000-Kev Protons And For Electron Capture By 5-150-Kev Protons, M. Eugene Rudd, R. D. Dubois, L. H. Toburen, C. A. Ratcliffe, T. V. Goffe Dec 1983

Cross Sections For Ionizaton Of Gases By 5-4000-Kev Protons And For Electron Capture By 5-150-Kev Protons, M. Eugene Rudd, R. D. Dubois, L. H. Toburen, C. A. Ratcliffe, T. V. Goffe

M. Eugene Rudd Publications

Using the parallel-plate-capacitor method and a capacitance manometer to determine pressures, total cross sections for the production of positive and negative charges were measured for 5-4000- keV-proton impact on He, Ne, Ar, Kr, Hz, N2, CO, 02, CH4, and C02. From these, ionization and electron-capture cross sections were obtained and fitted to semi-empirical equations describing the energy dependence in terms of a few parameters. At high energies very good agreement is obtained in the comparison of the ionization cross sections to earlier proton- and electron-impact measurements and with theoretical treatments where they …

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Reactive Scattering Cell For Atomic Hydrogen And Deuterium, John T. Park, E. Redd, T. J. Kvale, E. Rille Dec 1983

Reactive Scattering Cell For Atomic Hydrogen And Deuterium, John T. Park, E. Redd, T. J. Kvale, E. Rille

Physics Faculty Research & Creative Works

A design for a high-temperature reactive scattering cell for atomic hydrogen and atomic deuterium is described. At approximately 2700 K a dissociation of the molecular target species of over 95% has been obtained. The lifetime of 340 h of operation is sufficient for precision, long-time, differential cross-section measurements.

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Electron Drift Velocities In Gas Mixtures Of He, N2, And Co 2, Michael C. Cornell, Ian M. Littlewood, Howard L. Brooks, Kaare J. Nygaard Dec 1983

Electron Drift Velocities In Gas Mixtures Of He, N2, And Co 2, Michael C. Cornell, Ian M. Littlewood, Howard L. Brooks, Kaare J. Nygaard

Physics Faculty Research & Creative Works

An electron swarm experiment has been used to obtain electron drift velocities in the He:CO2:N2 mixtures 0:1:1, 3:1:2, and 3:1:1. The E/N range of 3 to 57 Td was studied with total gas pressure varied from 50 to 200 Torr. These particular mixtures have not been previously studied experimentally. Good agreement is observed between theoretical calculations and experimental data.

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Mst Radar Data-Base Management, Vincent B. Wickwar Dec 1983

Mst Radar Data-Base Management, Vincent B. Wickwar

All Physics Faculty Publications

No abstract provided.

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Isotope Effect And Momentum-Transfer Scaling In The Elastic-Scattering Differential Cross Sections For Hydrogen-Isotope Collision Systems, Eduard P. Rille, Jerry Peacher, Denver G. Seely, Thomas J. Kvale, E. Redd, D. M. Blankenship, John T. Park Dec 1983

Isotope Effect And Momentum-Transfer Scaling In The Elastic-Scattering Differential Cross Sections For Hydrogen-Isotope Collision Systems, Eduard P. Rille, Jerry Peacher, Denver G. Seely, Thomas J. Kvale, E. Redd, D. M. Blankenship, John T. Park

Physics Faculty Research & Creative Works

A projectile-dependent isotope effect was found for the elastic-scattering differential cross sections in the hydrogen-isotope collision systems. All four differential cross sections lie on a common curve if they are divided by the square of the reduced mass and plotted against momentum transfer. The experimental results are in satisfactory agreement with a simple Glauber-approximation calculation.

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Electron Capture Cross Sections For Tih⁴⁺, H. Sato, M. Kimura, A. E. Wetmore, Ronald E. Olson Dec 1983

Electron Capture Cross Sections For Tih⁴⁺, H. Sato, M. Kimura, A. E. Wetmore, Ronald E. Olson

Physics Faculty Research & Creative Works

Electron capture cross sections have been computed for Ti4++H to Ti3++H+ and Ti3++H+ to Ti4++H, where the reactants were in their ground states. The energy range investigated was 0.1 to 10 keV amu-1. The impact parameter perturbed-stationary-state method incorporating electron translation factors were used to calculate the cross sections. The molecular wavefunctions were generated using the pseudo-potential method. At 1 keV amu-1 ( nu rel=4.4*107 cm s-1), representative electron capture cross sections for the Ti4++H and Ti3++H+ reactions are 2*10-15 cm 2 and 1*10-17 cm2, respectively. An …

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Charge Transfer And Ionisation Processes Involving Multiply Charged Ions In Collision With Atomic Hydrogen, D. J.W. Hardie, Ronald E. Olson Dec 1983

Charge Transfer And Ionisation Processes Involving Multiply Charged Ions In Collision With Atomic Hydrogen, D. J.W. Hardie, Ronald E. Olson

Physics Faculty Research & Creative Works

Total cross sections are presented for the charge transfer reaction Xq++H(1s) to X(q-1)+H+ and ionization process Xq++H(1s) to Xq++H+-e-. Here Xq+ is a fully or partially stripped ion. The collision energy range lies between 25-200 keV amu-1. Cross sections are also given for charge transfer into particular ionic n states and n, l states for energies of 25 and 50 keV amu-1, where Xq+=H+, He 2+, C6+, O8+. The calculations were performed by the classical trajectory Monte Carlo method of Olson and …

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Breakdown Of Flavor Conservation In A Monopole Background, V. Parameswaran Nair Nov 1983

Breakdown Of Flavor Conservation In A Monopole Background, V. Parameswaran Nair

Publications and Research

We give a simple derivation of the catalysis of baryon decay and other flavor-changing processes by monopoles. The role of the axial anomaly is clarified. A general current-algebraic argument which clarifies the nature of flavor violation is also given.

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Ionic-Configuration-Interaction Effects On Xe 5S-Subshell Photoionization Processes, Göran Wendin, Anthony F. Starace Nov 1983

Ionic-Configuration-Interaction Effects On Xe 5S-Subshell Photoionization Processes, Göran Wendin, Anthony F. Starace

Anthony F. Starace Publications

Recent measurements of the 5s-subshell photoelectron angular distribution of xenon have found larger values for the asymmetry parameter β in the region of the 5s-subshell cross-section minimum than predicted by relativistic random-phase-approximation calculations. Final-state ionic configuration interaction is adduced as a possible explanation for this and other discrepancies.

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Electron Detachment For H-(D-) In Collisions With Ne, T. S. Wang, John B. Delos Nov 1983

Electron Detachment For H-(D-) In Collisions With Ne, T. S. Wang, John B. Delos

Arts & Sciences Articles

Total cross sections for electron detachment in collisions of H− and D− with Ne are calculated, using a model based on a first‐order solution to close‐coupled equations. Quantities needed for the calculation are the energy gap and the coupling between bound and free states. The energy gap is taken from previous calculations and the coupling is assumed to be of exponential form, with parameters adjusted to fit experimental data. Special examination is made of isotope effects in the cross sections.

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Search For Fractional Charges Produced In Heavy-Ion Collisions At 1.9 Gev/Nucleon, Michael A. Lindgren, David C. Joyce, Peter C. Abrams, Roger W. Bland, Robert T. Johnson, Tanya D. Knoop, Maureen H. Savage, Marion H. Scholz, Betty A. Young, Christopher L. Hodges, Alan A. Hahn, Gordon L. Shaw, Klaus S. Lackner, Howel G. Pugh, Richard Slansky Oct 1983

Search For Fractional Charges Produced In Heavy-Ion Collisions At 1.9 Gev/Nucleon, Michael A. Lindgren, David C. Joyce, Peter C. Abrams, Roger W. Bland, Robert T. Johnson, Tanya D. Knoop, Maureen H. Savage, Marion H. Scholz, Betty A. Young, Christopher L. Hodges, Alan A. Hahn, Gordon L. Shaw, Klaus S. Lackner, Howel G. Pugh, Richard Slansky

Physics

An experiment was performed to capture fractionally charged particles produced in heavy-ion collisions and to concentrate them in samples suitable for analysis by various techniques. Two of the samples so produced have been searched, with use of an automated version of Millikan's oil-drop apparatus. The beam was 56Fe at 1.9 GeV/nucleon, incident on a lead target. Less than one fractional charge per 1.0× 104 Fe-Pb collisions was found to be produced, and, with further assumptions, less than one per 2.0× 106 collisions.

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Active-Coupling Mixing Times For A Stirred Binary Liquid, Nalini Easwar, James V. Maher, D. J. Pine, W. I. Goldburg Oct 1983

Active-Coupling Mixing Times For A Stirred Binary Liquid, Nalini Easwar, James V. Maher, D. J. Pine, W. I. Goldburg

Physics: Faculty Publications

Mixing times measured for a stirred critical binary liquid mixture are seen to vary dramatically with Reynolds number, Prandtl number, and the initial value of the order parameter. These variations are far too large to be explained by passive-mixing calculations; they also differ in significant respects from the active-mixing predictions of Ruiz and Nelson.

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Convexity Of The Free Energy In Some Real-Space Renormalization-Group Approximations, Miron Kaufman, Robert B. Griffiths Oct 1983

Convexity Of The Free Energy In Some Real-Space Renormalization-Group Approximations, Miron Kaufman, Robert B. Griffiths

Miron Kaufman

Whereas the free energy for a spin system in a hierarchical lattice will be convex as a function of appropriate parameters (and thus the heat capacity positive, etc.), the same need not be true of a corresponding approximate real-space renormalization-group method applied to a Bravais lattice. Some examples are given which illustrate this point.

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Ionization Of Heavy Atoms By Polarized Relativistic Protons, P.T. Leung, M. L. Rustgi Oct 1983

Ionization Of Heavy Atoms By Polarized Relativistic Protons, P.T. Leung, M. L. Rustgi

Physics Faculty Publications and Presentations

The effect due to the polarization of the incident high-energy (~GeV) proton beam on the ionization cross section of heavy atoms is investigated. In particular, with the use of Darwin wave functions for the atomic electron, the effect for hydrogenlike atoms is worked out. A numerical illustration shows that the polarization effect is completely insignificant. The authors also conclude that the K-shell ionization process is completely insensitive to the polarization of the incident beam.

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Close-Coupling Calculations For Naar, Nane, And Nahe, Linda Lindroth Vahala Oct 1983

Close-Coupling Calculations For Naar, Nane, And Nahe, Linda Lindroth Vahala

Physics Theses & Dissertations

The non-adiabatic close-coupled theory, developed by Mies and by George, is employed in a time-independent molecular calculation for Na-rare gas collisions in a radiations field. The intensity of the Na D1/D2 lines is calculated for both blue- and red-wing excitation and is in good agreement with the experimental results of Havey, Copeland, and Wang for NaAr. The effects of different Born-Oppenheimer potentials on D1/D2 line intensity is considered by also treating NaNe and NaHe. The individual parity contributions to the line intensities are significantly different from each other.

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Composition Of The Critical Nucleus In Multicomponent Vapor Nucleation, Gerald Wilemski Oct 1983

Composition Of The Critical Nucleus In Multicomponent Vapor Nucleation, Gerald Wilemski

Physics Faculty Research & Creative Works

No abstract provided.

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Fe3O4 Precipitation In Magnetotactic Bacteria, Richard B. Frankel, Georgia C. Papaefthymiou, Richard P. Blakemore, Wendy O'Brien Sep 1983

Fe3O4 Precipitation In Magnetotactic Bacteria, Richard B. Frankel, Georgia C. Papaefthymiou, Richard P. Blakemore, Wendy O'Brien

Physics

Using Mössbauer resonance spectroscopy of 57Fe, we have determined the nature and distribution of major iron compounds in the magnetotactic bacterium Aquaspirillum magnetotacticum. In addition to magnetite (Fe3O4), cells contained a low-density hydrous ferric oxide, a high-density hydrous ferric oxide (ferrihydrite), and ferrous iron. Analysis at different temperatures of whole cells harvested early and late in growth, of mutant cells unable to synthesize magnetite, and of cell fractions enriched in 57Fe indicated that Fe3O4 precipitation resulted from partial reduction of the high-density hydrous ferric oxide precursor.

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Stimulated Emission And The Flat Balmer Decrements Of Cataclysmic Variable Stars, Moshe Elitzur, Gary J. Ferland, W. G. Mathews, G. A. Shields Sep 1983

Stimulated Emission And The Flat Balmer Decrements Of Cataclysmic Variable Stars, Moshe Elitzur, Gary J. Ferland, W. G. Mathews, G. A. Shields

Physics and Astronomy Faculty Publications

Balmer emission lines from cataclysmic variables often have nearly equal intensities rather than the rapid decrement predicted by simple nebular theory. Traditionally, this has been interpreted in terms of local thermodynamic equilibrium emission from a dense gas with small volume located just above the accretion disk. In this Letter we show that the intense radiation field within a close binary system can affect excited-state populations and optical emission in ways which allow a relatively low density gas to closely mimic the high-density situation. In at least one case, the old nova V603 Aql, the emitting gas has a low density …

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Competing Criticality Of Short- And Infinite-Range Interactions On The Cayley Tree, Mehran Kardar, Miron Kaufman Sep 1983

Competing Criticality Of Short- And Infinite-Range Interactions On The Cayley Tree, Mehran Kardar, Miron Kaufman

Miron Kaufman

The Ising model, with equivalent-neighbor and nearest-neighbor interactions of Cayley tree connectivity, is solved exactly. Breaking translational symmetry by turning on the Cayley interactions is analogous to lowering spatial dimensionality in Bravais lattices. A range of classical criticality, a point of logarithmic corrections, a range of continuously varying power-law singularities, and a point of exponential singularity are successively encountered.

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Self‐Refraction Of Nonlinear Capillary‐Gravity Waves, Partha P. Banerjee, Adrianus Korpel, Karl E. Lonngren Sep 1983

Self‐Refraction Of Nonlinear Capillary‐Gravity Waves, Partha P. Banerjee, Adrianus Korpel, Karl E. Lonngren

Electrical and Computer Engineering Faculty Publications

Self‐refraction effects have been observed during the propagation of deep‐water capillary‐gravity waves. The observations are shown to be in qualitative agreement with the theory of self‐focusing and defocusing in a cubically nonlinear medium in the presence of diffraction.

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Explicit Equations For The Second Brewster Angle Of An Interface Between A Transparent And An Absorbing Medium, R. M.A. Azzam Sep 1983

Explicit Equations For The Second Brewster Angle Of An Interface Between A Transparent And An Absorbing Medium, R. M.A. Azzam

Electrical Engineering Faculty Publications

The second Brewster angle ΦB2, at which the ratio Rp/Rs of intensity reflectances Rp and Rs for the parallel (p) and the perpendicular (s) polarizations of a dielectric-conductor interface reaches a minimum, is determined by Im[(u - ∊)(u - ∊)2/(u - 2∊)2] = 0, where ∊ is the complex ratio of dielectric constants of the media of refraction and incidence, ∊ = ∊/(∊ + 1), and u= sin2ΦB2. An equivalent quartic equation in u …

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Search For Fractional Charges In Water, David C. Joyce, Peter C. Abrams, Roger W. Bland, Robert T. Johnson, Michael A. Lindgren, Maureen H. Savage, Marion H. Scholz, Betty A. Young, Christopher L. Hodges Aug 1983

Search For Fractional Charges In Water, David C. Joyce, Peter C. Abrams, Roger W. Bland, Robert T. Johnson, Michael A. Lindgren, Maureen H. Savage, Marion H. Scholz, Betty A. Young, Christopher L. Hodges

Physics

Results are presented from a search for fractional charges in water from a variety of natural sources. About 30 000 water drops have been measured, comprising 51 μg of water and dissolved materials. No evidence for fractional charge was seen.

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Catalysis Of Flavor Nonconservation By Monopoles, V. Parameswaran Nair Aug 1983

Catalysis Of Flavor Nonconservation By Monopoles, V. Parameswaran Nair

Publications and Research

A simple argument based on current algebra is given to show how monopoles can lead to baryon decay and other flavor-changing processes.

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The Application Of Exact Electrodiffusion Theory To Ion Transport Across Lipid Bilayer Membranes, Scott Cohen Aug 1983

The Application Of Exact Electrodiffusion Theory To Ion Transport Across Lipid Bilayer Membranes, Scott Cohen

Dissertations and Theses

The question of how ions interact with each other and with the potential energy barrier in thin lipid bilayer membranes has interested investigators for several years. The application of electrodiffusion theory to the study of this question is the central theme of this work. We have calculated current-voltage curves for barriers of various shapes and heights, in each case by means of numerically integrating the exact electrodiffusion equation as well as this same equation in the constant field approximation. We have also calculated the total charge in the membrane for the same conditions under which we have calculated the current-voltage …

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Magnetic Field Behavior Of A Josephson-Junction Array: Two-Dimensional Flux Transport On A Periodic Substrate, Richard A. Webb, Richard F. Voss, G. Grinstein, P. M. Horn Aug 1983

Magnetic Field Behavior Of A Josephson-Junction Array: Two-Dimensional Flux Transport On A Periodic Substrate, Richard A. Webb, Richard F. Voss, G. Grinstein, P. M. Horn

Faculty Publications

This Letter reports measurements down to 3 mK of the magnetic field dependence of the resistance and critical current of a weakly coupled periodic array of Josephson junctions. Below 700 mK the resistance is an oscillatory function of field. The temperature dependence of the resistance for integral numbers of flux quanta per cell suggests the existence of a Kosterlitz-Thouless transition involving the unbinding of defects in the flux lattice.

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