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Articles 34801 - 34830 of 36535

Full-Text Articles in Physical Sciences and Mathematics

The Creation Of Holograms Utilizing Fiber Optics, Abdul Rahim Omar Aug 1981

The Creation Of Holograms Utilizing Fiber Optics, Abdul Rahim Omar

Masters Theses

Holography involves the interference of two light beams, namely a reference beam and an object beam. Instead of the conventional method using beam splitters and mirrors to direct the light path, fiber optic bundles are used and high quality holograms have been produced. When fiber optic bundles are used, a spatial filter is not needed to produce a "clean" beam of light for the reference beam. Fiber optic bundles also provide greater flexibility of illumination for the object beam and/or fir the reference beam. Also, it is easier to illuminate the object from many directions. Finally, the distance from the …

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The Water Monomer On The Prism Face Of Ice And Above A Four Layer Ice Basal Face Ledge: An Effective Pair Potential Model, Barbara N. Hale, Jerry Kiefer, Carolyn A. Ward Aug 1981

The Water Monomer On The Prism Face Of Ice And Above A Four Layer Ice Basal Face Ledge: An Effective Pair Potential Model, Barbara N. Hale, Jerry Kiefer, Carolyn A. Ward

Physics Faculty Research & Creative Works

A previous study of the water monomer on the basal faces of ice is extended to consider the interaction of the water molecule with a rigid prism face of ice and with an ice basal face ledge. The effective central force H2O-H2O potentials of Stillinger and Rahman are used to generate maximal binding energy surfaces for the H2O adsorbed on the sample substrates. The results indicate that the prism face of ice binds the water molecule more strongly than the basal faces, and the step on the basal face serves to expose high binding …

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A Study Of The Films Produced By The Aluminum/Water Reaction Using Rutherford Backscattering Spectroscopy, Reed L. Shilts Aug 1981

A Study Of The Films Produced By The Aluminum/Water Reaction Using Rutherford Backscattering Spectroscopy, Reed L. Shilts

Masters Theses

This work compares the action of pure water to various aqueous electrolytes on aluminum surface film formation at about 100°C. The electrolytes were pure water with various inhibitor ions added. The ions were nitrate, tungstate, borate, molybdate, silicate, phosphate, a mixture of nitrate and molybdate, and a mixture of silicate and molybdate. The investigative technique was Rutherford backscattering spectroscopy (RBS) using 2 MeV alpha particles with an annular detector set at 180 degrees for maximum elemental resolution. RBS was chosen for this investigation because it offers in an easily interpretable manner a relatively fast and semi-quantitative method of analysis of …

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Detector Geometry For Cascade Photon Experiments, Roger Minoru Munechika Aug 1981

Detector Geometry For Cascade Photon Experiments, Roger Minoru Munechika

Masters Theses

An observation of cascading optical photons can be used to determine an absolute excitation cross section for the intermediate state without the need of standard lamp calibration. In order to reduce the data an angular correlation function and an angular distribution function must be known. These functions depend on the alignment of the upper excited state and the polarization of the light emitted in the lower part of the cascade. However, at certain angles of observation the values of the required functions are known regardless of the alignment or polarization. A computer search is done to find these angles for …

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Comment On Particle Mixing And Delta-I= 3/2 Terms In Non-Leptonic Weak Decays, Br Holstein Jul 1981

Comment On Particle Mixing And Delta-I= 3/2 Terms In Non-Leptonic Weak Decays, Br Holstein

Barry R Holstein

A recent paper by Gusbin concludes that ΔI=3/2 terms in K→πη can substantially modify particle-mixing contributions to K+→π+π0. Using techniques which can successfully reproduce the experimental features of the K→ππ decays, we argue that this seems unlikely.

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Macroscopic Quantum Tunneling In 1-Μm Nb Josephson Junctions, Richard F. Voss, Richard A. Webb Jul 1981

Macroscopic Quantum Tunneling In 1-Μm Nb Josephson Junctions, Richard F. Voss, Richard A. Webb

Faculty Publications

The probability distributions for switching out of the superconducting state of low-cur-rent-density 1-μm Nb Josephson junctions with capacitance ≈ 0.1 pF have been measured as a function of temperature T down to 3 mK. Below 100 mK the distribution widths become independent of T. The results are in excellent agreement with predictions for the quantum tunneling of the (macroscopic) junction phase that include the reduction of tunneling rates due to dissipation.

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Photoionization Of The 4D10 Subshell Of Cadmium: Photoelectron Angular Distributions And Polarization Of Fluorescence Radiation, Constantine E. Theodosiou, Anthony F. Starace, B.R. Tambe, Steven T. Manson Jul 1981

Photoionization Of The 4D10 Subshell Of Cadmium: Photoelectron Angular Distributions And Polarization Of Fluorescence Radiation, Constantine E. Theodosiou, Anthony F. Starace, B.R. Tambe, Steven T. Manson

Anthony F. Starace Publications

Relativistic Dirac-Fock calculations are presented for the photoelectron angular distribution asymmetry parameter β corresponding to 4d-subshell photoionization in Cd and for the linear polarization PL of the subsequent fluorescence radiation, for photon energies less than 185 eV. Near threshold, our results for β lie lower than previous relativistic Dirac-Slater and nonrelativistic many-body-perturbation-theory (MBPT) calculations. The agreement with very recent measurements by Heinzmann and Schönhense is very good. Our calculations show that PL (2D5/2→2P3/2)=-0.059 and -0.058 at incident photon energies hν=40.2 and 45.6 eV, respectively. These results lie …

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Exactly Soluble Ising Models On Hierarchical Lattices, Miron Kaufman, Robert B. Griffiths Jul 1981

Exactly Soluble Ising Models On Hierarchical Lattices, Miron Kaufman, Robert B. Griffiths

Miron Kaufman

Certain approximate renormalization-group recursion relations are exact for Ising models on special hierarchical lattices, as noted by Berker and Ostlund. These lattice models provide numerous examples of phase coexistence and critical points at finite temperatures, including cases of continuously varying critical exponents and phase transitions without phase coexistence. The lattices are, typically, quite inhomogeneous and may possess several inequivalent limits as infinite lattices.

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Negative Acceleration Components For A Relativistic Particle, James A. Lock Jul 1981

Negative Acceleration Components For A Relativistic Particle, James A. Lock

Physics Faculty Publications

Newtonian acceleration is considered in the light of special relativity theory with the result that the component of acceleration in the direction of an arbitrary applied force is always positive.(AIP)

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Implications Of Nuclear Parity Non-Conservation, Jf Donoghue, Br Holstein Jun 1981

Implications Of Nuclear Parity Non-Conservation, Jf Donoghue, Br Holstein

Barry R Holstein

From recent developments in the area of nuclear parity nonconservation we extract evidence for (1) SU(3) /soft-pion breaking in weak pionic vertices, and (2) larger values of quark masses than have been used in previous evaluations of "penguin" matrix elements.

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Magnetotactic Bacteria At The Geomagnetic Equator, Richard B. Frankel, R. P. Blakemore, F. F. Torres De Araujo, D. M. S. Esquivel, J. Danon Jun 1981

Magnetotactic Bacteria At The Geomagnetic Equator, Richard B. Frankel, R. P. Blakemore, F. F. Torres De Araujo, D. M. S. Esquivel, J. Danon

Physics

Magnetotactic bacteria are present in fresh water and marine sediments of Fortaleza, Brazil, situated close to the geomagnetic equator. Both South-seeking and North-seeking bacteria are present in roughly equal numbers in the same samples. This observation is consistent with the hypothesis that the vertical component of the geomagnetic field selects the predominant polarity type among magnetotactic bacteria in natural environments.

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A Unidirectional, Pulsed Far-Infrared Ring Laser, W.A. Peebles, Donald P. Umstadter, D.L. Brower, N.C. Luhmann Jr. Jun 1981

A Unidirectional, Pulsed Far-Infrared Ring Laser, W.A. Peebles, Donald P. Umstadter, D.L. Brower, N.C. Luhmann Jr.

Donald Umstadter Publications

The first study of a pulsed, far-infrared, ring laser is described. Unidirectional, traveling-wave operation is observed, thereby eliminating the spatial hole burning effects present in linear cavities. Single-mode output powers of 100 kW have been obtained.

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Brownian Motion In A Flowing Fluid Revisited, John D. Ramshaw Jun 1981

Brownian Motion In A Flowing Fluid Revisited, John D. Ramshaw

Physics Faculty Publications and Presentations

It is shown how the phenomenon of osmosis may be treated using the phenomenological theory of Brownian motion in a flowing fluid. The theory is also generalized to include viscous stresses in the particle and mixture momentum equations.

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Electron Capture At Very Small Scattering Angles From Atomic Hydrogen By 25-125-Kev Protons, Paul J. Martin, D. M. Blankenship, Thomas J. Kvale, E. Redd, Jerry Peacher, John T. Park Jun 1981

Electron Capture At Very Small Scattering Angles From Atomic Hydrogen By 25-125-Kev Protons, Paul J. Martin, D. M. Blankenship, Thomas J. Kvale, E. Redd, Jerry Peacher, John T. Park

Physics Faculty Research & Creative Works

Differential cross sections for electron capture in collisions between protons and hydrogen atoms have been experimentally determined for incident proton energies of 25, 60, and 125 keV in the center-of-mass scattering-angle range of 0-3 mrad. The experimental results compare more favorably with the results of both a multistate and a two-state calculation than with the results of a continuum distorted-wave-approximation calculation. There is no evidence of a Jackson-Schiff-type minimum.

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Differential Cross Sections For Electron Capture From Helium By 25- To 100-Kev Incident Protons, Paul J. Martin, Kenneth E. Arnett, D. M. Blankenship, Thomas J. Kvale, Jerry Peacher, E. Redd, V. C. Sutcliffe, John T. Park, Chiidong Lin, Jim H. Mcguire Jun 1981

Differential Cross Sections For Electron Capture From Helium By 25- To 100-Kev Incident Protons, Paul J. Martin, Kenneth E. Arnett, D. M. Blankenship, Thomas J. Kvale, Jerry Peacher, E. Redd, V. C. Sutcliffe, John T. Park, Chiidong Lin, Jim H. Mcguire

Physics Faculty Research & Creative Works

Experimentally and theoretically determined differential cross sections are reported for electron capture in collisions of protons with helium atoms for incident proton energies of 25, 30, 50, and 100 keV and for center-of-mass scattering angles of 0.0 to 2.0 mrad. The magnitudes of the experimentally determined differential cross sections decrease from 10-10 to 10-12 cm2/sr within the 0.0-0.8-mrad range of the center-of-mass scattering angle. At approximately 0.8 mrad a distinct change in the slope of the differential cross section is observed. The experimental results which are for capture into all bound states of hydrogen are compared …

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Direct Nmr Observation Of Rotational Freeze-Out In The Smectic C-Phase, Demetri J. Photinos, Philip J. Bos, Mary E. Neubert, J. William Doane May 1981

Direct Nmr Observation Of Rotational Freeze-Out In The Smectic C-Phase, Demetri J. Photinos, Philip J. Bos, Mary E. Neubert, J. William Doane

Philip J. Bos

We report here a simple and direct observation that the molecular long axis is not, on the average, a rotation axis for the entire molecule in the smectic C phase (rotational freeze-out). This observation is made in the compound 4-n-heptyl-d15-oxybenzoic acid-d1 where experiment clearly shows that the principal axes of the time-averaged deuterium quadrupole interactions at specific sites of the hydrocarbon chain are not all parallel, demonstrating that they do not share a common axis of rotation.

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Detection Of Vibrationally Excited Nitrogen By Trapped Electron And Electron Transmission Methods, J.A. Michejda, L.J. Dube, Paul Burrow May 1981

Detection Of Vibrationally Excited Nitrogen By Trapped Electron And Electron Transmission Methods, J.A. Michejda, L.J. Dube, Paul Burrow

Paul Burrow Publications

Two techniques for detection of vibrationally excited nitrogen using low-energy electron scattering are described. The first technique uses the trapped electron method to observe excitation from N2ν into the B3Пg state near threshold. From the known Franck-Condon factors, the contribution from excited vibrational levels may be unfolded. The second technique employs the electron transmission method to detect sharp structure in the total scattering cross section resulting from the formation of temporary negative ions. Because of uncertainties in the total scattering cross sections from each of the vibrational levels, the transmission method is less accurate than …

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A Critical Study Of Nonlinear Echo Phenomena, Monish Ranjan Chatterjee May 1981

A Critical Study Of Nonlinear Echo Phenomena, Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

The present thesis attempts to give a concise and critical account of the evolution of the echo phenomena over the last thirty years. Starting with spin and photon echoes, which were among the earliest to be observed and studied, the thesis explores the experimental findings and the models proposed in connection with the more contemporary echo experiments, viz. those involving electroacoustic or polarization echoes in single and polycrystalline piezoelectric materials and in powders. Although the investigations regarding the various mechanisms of short and long term echo formation are by no means complete, a coherent picture is beginning to emerge as …

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Theory Of Near-Adiabatic Collisions. Iii. Coupled Equations Arising From Expansions Involving Single-Center States, John B. Delos May 1981

Theory Of Near-Adiabatic Collisions. Iii. Coupled Equations Arising From Expansions Involving Single-Center States, John B. Delos

Arts & Sciences Articles

The conventional quantum-mechanical formulation of near-adiabatic collision theory is known to have a number of defects. These defects arise because the usual description does not account for the displacement of electronic states with moving nuclei, or for the change of momentum of the electron as it jumps from one moving nucleus to the other. The purpose of this series of papers is to develop an improved theory, in which such effects are taken into account. In this paper, we show that displacement and momentum-transfer effects can be incorporated into the theory in a very simple way, provided that the wave …

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Rare-Earth-Rich Metallic Glasses. I. Magnetic Hysteresis, George C. Hadjipanayis, David J. Sellmyer, B. Brandt Apr 1981

Rare-Earth-Rich Metallic Glasses. I. Magnetic Hysteresis, George C. Hadjipanayis, David J. Sellmyer, B. Brandt

David Sellmyer Publications

An anomalous magnetic behavior has been observed in rare-earch-rich metallic glasses of the composition (R75Au25)100-xBx where R denotes Pr, Gd, Tb, Er and x=0,10. The observed hysteresis in all samples except Gd at liquid-helium temperatures is due to the large anisotropy which develops below the ordering temperature. High-field-magnetization measurements up to 220 kOe were used to determine the spontaneous magnetization and the magnetic anisotropy constant which was found to be of order 108 erg/cm3 for the Tb and Er glasses. These parameters were used together with the observed remanence ratio to …

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Ionization By Low And Intermediate Energy Ion And Neutral Beams, M. Eugene Rudd Apr 1981

Ionization By Low And Intermediate Energy Ion And Neutral Beams, M. Eugene Rudd

M. Eugene Rudd Publications

One of the most important basic processes that take place in collisions of atomic systems is ionization resulting in the emission of electrons. A complete understanding of this process is complicated by the fact that electron emission can take place via a number of mechanisms, some of which are related. Simple measurements of the cross section for electron ejection as a function of projectile velocity does not usually provide enough information to unravel the various mechanisms. But cross sections which are differential in the angle and energy of the ejected electrons, which are now available for protons on a variety …

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Three-Component Model And Tricritical Points: A Renormalization-Group Study., Miron Kaufman, Robert B. Griffiths, Julia M. Yeomans, Michael E. Fisher Apr 1981

Three-Component Model And Tricritical Points: A Renormalization-Group Study., Miron Kaufman, Robert B. Griffiths, Julia M. Yeomans, Michael E. Fisher

Miron Kaufman

The global phase diagram for a three-component lattice gas or spin-one Ising model with general single-site and nearest-neighbor "ferromagnetic" interactions is worked out for twodimensional lattices using a Migdal-Kadanoff recursion relation. It differs in important qualitative respects from the corresponding mean-field phase diagram. The set of fixed points and flows provides the characteristic'phase diagrams of the three-state Potts multicritical point and the ordinary (n =1) tricritical point in a complete set of symmetry-breaking fields. The latter is associated, in this renormalization-group scheme, with seven distinct critical fixed points, a number which is surprisingly large.

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University-School Cooperation, Herman Feshbach, Robert Fuller Apr 1981

University-School Cooperation, Herman Feshbach, Robert Fuller

Robert G. Fuller Publications

We have a growing concern with the deterioration in both the quality and quantity of secondary physics education in the US. These concerns have recently been addressed by an APS panel chaired by Gertrude S. Goldhaber.

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Rare-Earth-Rich Metallic Glasses. Ii. Magnetic Viscosity, George C. Hadjipanayis, David J. Sellmyer Apr 1981

Rare-Earth-Rich Metallic Glasses. Ii. Magnetic Viscosity, George C. Hadjipanayis, David J. Sellmyer

David Sellmyer Publications

Magnetic viscosity measurements on amorphous Tb75Au25 and (Er65Fe35)90B10 alloys are presented in the temperature range of 1.3 to 30 K. The magnetization in a steady magnetic field is found to follow a logarithmic time dependence for times up to 400 s suggesting a spectrum of activation energies. The magnetic viscosity parameters were used to investigate the temperature dependence of the observed large coercive fields and to study intrinsic temperature and thermal activation effects. It is found that the large change of the coercive field at very low temperatures is mainly …

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Molecular Effects In Beam-Foil Collision-Induced Alignment Of He I, Timothy J. Gay, H. G. Berry, R. Deserio Apr 1981

Molecular Effects In Beam-Foil Collision-Induced Alignment Of He I, Timothy J. Gay, H. G. Berry, R. Deserio

Timothy J. Gay Publications

We have measured the alignment of beam-foil collision-excited states of He I produced by bombarding carbon foils of various (1.3-110 μg/cm2) areal densities with beams of He+ and HeH+. In addition, we have measured the total light yield of several transitions in He I, He II, and H as a function of foil thickness using beams of HeH+ ions. Experiments were done with He-foil exit energies of 125, 500, 550, and 650 keV. He I alignment decreases in all cases for the thinnest foils when molecular projectiles are used. Total light intensities generally increase …

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Energy Dependence Of Alignment In Foil Collision-Excited N=3 States Of He I, Timothy J. Gay, H. G. Berry, R. Deserio, H. P. Garnir, R. M. Schectman, N. Schaffel, R. D. Hight, D.J. Burns Apr 1981

Energy Dependence Of Alignment In Foil Collision-Excited N=3 States Of He I, Timothy J. Gay, H. G. Berry, R. Deserio, H. P. Garnir, R. M. Schectman, N. Schaffel, R. D. Hight, D.J. Burns

Timothy J. Gay Publications

We have measured the beam-foil collision-induced alignment of the 3p 1P, 3p 3P, 3d 1D, and 3d 3D states of He I for He+ beam energies between 30 and 1300 keV. The alignment of all four states is found to vary with beam-current density as well as energy. The number of secondary electrons emitted per incident ion, γ, has also been measured as a function of foil temperature and beam energy between 400 and 1400 keV. The rate of change of both alignment and γ with foil temperature exhibits …

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Theory Of Electronic Excitations In Slow Atomic Collisions, John B. Delos Apr 1981

Theory Of Electronic Excitations In Slow Atomic Collisions, John B. Delos

Arts & Sciences Articles

This review deals with quantitative descriptions of electronic transitions in atom-atom and ion-atom collisions. In one type of description, the nuclear motion is treated classically or semiclassically, and a wave function for the electrons satisfies a time-dependent Schrödinger equation. Expansion of this wave function in a suitable basis leads to time-dependent coupled equations. The role played by electron-translation factors in this expansion is noted, and their effects upon transition amplitudes are discussed. In a fully quantum-mechanical framework there is a wave function describing the motion of electrons and nuclei. Expansion of this wave function in a basis which spans the …

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Interferometer Studies Of Equatorial Fregion Irregularities And Drifts, E. Kudeki, Bela G. Fejer, D. T. Farley, H. M. Ierkic Apr 1981

Interferometer Studies Of Equatorial Fregion Irregularities And Drifts, E. Kudeki, Bela G. Fejer, D. T. Farley, H. M. Ierkic

Bela G. Fejer

A radar interferometer technique developed at Jicamarca, Peru and first used to study electrojet irregularities has now been used successfully to study plasma turbulence in the equatorial F region. Our first results have shown that the most ‘turbulent’ echoes appear to come from a region that extends for tens of kilometers in altitude but for only a kilometer or less in the east-west direction. This slab may very well be the wall of a depleted region, a plasma ‘bubble’. Sometimes the irregularities can be tracked as they move eastward or westward. Velocity profiles for the evening period obtained in this …

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Induced Tensor And Ft Asymmetries, Br Holstein Mar 1981

Induced Tensor And Ft Asymmetries, Br Holstein

Barry R Holstein

Looked at from a model-independent point of view, the existence of a non-zero first class induced tensor form factor appears to provide a substantial contribution to the observed ft asymmetry in mirror Gamow-Teller beta decays. However, we demonstrate that, when analyzed in terms of the impulse approximation, this is only a negligibly small effect. RADIOACTIVITY Calculated contribution to ft asymmetry from first class induced tensor.

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Magnetic Properties Of Rare Earth-Gallium-Iron Glasses, S.G. Cornelison, David J. Sellmyer, George C. Hadjipanayis Mar 1981

Magnetic Properties Of Rare Earth-Gallium-Iron Glasses, S.G. Cornelison, David J. Sellmyer, George C. Hadjipanayis

David Sellmyer Publications

Results of magnetic susceptibility, high-field magnetization, and Mössbauer effect are reported for several R-Ga and R-Ga-Fe metallic glasses, where R = Pr and Tb. Magnetic ordering temperatures, effective moments, and coercive forces were determined. In certain cases the data indicate that the low temperature states of magnetic order are asperomagnetic or spin-glass-like. For (Pr80Ga20)80Fe20, several anomalies were observed including a large coercive field (45 kOe) at 100 K. Journal of Applied Physics is copyrighted by The American Institute of Physics.

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