Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Physics

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 35821 - 35850 of 36520

Full-Text Articles in Physical Sciences and Mathematics

Infrared Reflectivity Of Doped Insb And Cds, Thomas J. Mcmahon, Robert John Bell Dec 1969

Infrared Reflectivity Of Doped Insb And Cds, Thomas J. Mcmahon, Robert John Bell

Physics Faculty Research & Creative Works

The coupling of free carriers and lattice-vibrational modes in CdS and InSb was investigated by using reflectance measurements. When the free-carrier concentration is such that the longitudinal-optical-mode frequency is at or near the plasma frequency, the longitudinal mode takes on a mixed character and is shifted in a manner similar to that described by Varga in 1965, while the transverse mode remains fixed. The electron effective masses in such a situation can be determined with the lattice effects excluded. In the case of CdS, the polaron mass and additional absorption in the plasma mode above the longitudinal-optical phonon frequency must …

Go to article

A Study Of Some Matrix Elements For The Four-Pion Decay Mode Of Neutral Bosons, George Victor Weller Dec 1969

A Study Of Some Matrix Elements For The Four-Pion Decay Mode Of Neutral Bosons, George Victor Weller

Masters Theses

No abstract provided.

Go to article

Nuclear Structure Studies In 90Y, Ronald E. Goans Dec 1969

Nuclear Structure Studies In 90Y, Ronald E. Goans

Masters Theses

Differential cross sections (12.5° to 47.5°) were measured for the 89Y (d,p) reaction with 33.3 Mev deuterons from the Oak Ridge Isochronous Cyclotron. Proton spectra up to 5 Mev excitation in the 90Y were observed in nuclear emulsions exposed in the focal plane of the broad range spectrograph. The resolution was approximately 25 Kev. The excitation energies agreed within experimental error with (d,p) experiments at 12 Mev and 15 Mev. Comparisons were made with DWBA calculations and ℓ-transfers were assigned to 25 levels. The ℓ-transfers and spectroscopic factors are in satisfactory agreement with previous papers for most strong …

Go to article

Vibrational Excitation By Electron Impact Near Threshold In H2, D2, N2, And Co, Paul Burrow, G.J. Schulz Nov 1969

Vibrational Excitation By Electron Impact Near Threshold In H2, D2, N2, And Co, Paul Burrow, G.J. Schulz

Paul Burrow Publications

The trapped-electron method is applied to the measurement of the slopes of the vibrational cross sections near their respective thresholds. Absolute values are obtained by normalization to positive-ion cross sections. The values obtained in H2 are 43 for v=1, 0.72, for v=2, 0.04, for v=3, and 0.003, for v=4, in units of 10-18 cm2/eV. The values for N2 are 2.5 for v=1 and about 0.02 for v=2, whereas, the values for CO are much larger, i.e., 120 for v=1 and 2.4 for v=2. Various corrections that are …

Go to article

Hyperfine Interaction In Gd In Diamagnetic, Metallic Hosts, Richard B. Frankel Nov 1969

Hyperfine Interaction In Gd In Diamagnetic, Metallic Hosts, Richard B. Frankel

Physics

Mössbauer effect data for dilute, paramagnetic Gd in the diamagnetic, metallic hosts YAl2, YbAl2 and Al are analyzed and yield a local conduction electron polarization contribution to the Gd hyperfine field of +140 kOe.

Go to article

Mössbauer Effect In The Ferroelectric Pbtio₃-Bifeo₃ Solid Solutions, C. M. Yagnik, James P. Canner, Robert Gerson, William Joseph James Nov 1969

Mössbauer Effect In The Ferroelectric Pbtio₃-Bifeo₃ Solid Solutions, C. M. Yagnik, James P. Canner, Robert Gerson, William Joseph James

Physics Faculty Research & Creative Works

The Mössbauer spectra of the system (PbTiO3)0.95(BiFeO3)0.05 have been studied from room temperature to 585°C. From the isomer-shift of 0.491±0.02 mmsec-1 at room temperature, the ionicity is found to be 60% ± 20%. A discontinuity in the plot of isomer-shift versus temperature at Tc is observed. The quadrupole splitting at room temperature is 0.295 ± 0.02 mm/sec-1. A dip in the Mössbauer fraction is observed at the Curie temperature.

Go to article

Interpretation Of A Unified Theory Of Gravitation And Symmetry Breaking, David Peak, A Inomata Nov 1969

Interpretation Of A Unified Theory Of Gravitation And Symmetry Breaking, David Peak, A Inomata

All Physics Faculty Publications

The formalism of Moen and Moffat is interpreted as a Yang-Mills theory set in a space-time generally endowed with curvature and torsion.

Go to article

Particle Tracks In Emulsion, Robert Katz, E. J. Kobetich Oct 1969

Particle Tracks In Emulsion, Robert Katz, E. J. Kobetich

Robert Katz Publications

A new theory of track formation in emulsion accounts for the tracks of charged particles on the basis of a theory developed earlier for the response of biological molecules and NaI(T1) to energetic heavy ions. The probability that an emulsion grain will remain undeveloped when exposed to δ rays depositing a mean energy E is assumed to be e-E/E0 where E0 is the dose at which l/e (37%) of the emulsion grains remain undeveloped, as in the one-or-more-hit cumulative Poisson distribution. The parameter E0 incorporates variations in emulsion properties and processing conditions. Calculation of …

Go to article

Nuclear Zeeman Effect In W182 In Iron, Richard B. Frankel, Y. Chow, L. Grodzins, J. Wulff Oct 1969

Nuclear Zeeman Effect In W182 In Iron, Richard B. Frankel, Y. Chow, L. Grodzins, J. Wulff

Physics

The Mössbauer effect in the 100-keV 2+→0+ transition in W182 was observed with dilute tungsten in iron alloy absorbers with concentrations from 0.5-5.0 at.%W at 4.2°K. From the Zeeman spectra in external longitudinal magnetic fields, the g factor of the first excited 2+ state was found to be 0.22±0.02, and the hyperfine field at tungsten nuclei in iron was found to be -708±25 kOe. The hyperfine interaction for Fe57 in these alloys was also measured, and the results are compared with measurements on alloys of Fe with other 5d impurities and with neutron diffraction measurements.

Go to article

A Technique For The Rapid Measurement Of Thermoelectric Power, G.R. Caskey, David J. Sellmyer, L.G. Rubin Oct 1969

A Technique For The Rapid Measurement Of Thermoelectric Power, G.R. Caskey, David J. Sellmyer, L.G. Rubin

David Sellmyer Publications

A new technique is described for rapid measurement of the thermoelectric power of rod-shaped specimens over a wide temperature range. The apparatus utilizes sensitive commercial dc amplifier for the sample and temperature gradient voltages and a multiple-point recorder for sampling these voltages as well as the sample temperature signal. The technique eliminates spurious thermal emf's in the leads and is based upon on-the-run recording of the sample and temperature gradient voltages as the temperature gradient slowly increases. As a test of this technique, the thermopower of pure nickel was measured between 4.2 and 300 K and the results are compared …

Go to article

11th Annual Rocky Mountain Spectroscopy Conference Aug 1969

11th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 11th annual meeting of the Rocky Mountain Spectroscopy Conference, sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, August 4-5, 1969.

Go to article

Nmr Determination Of The Conduction-Electron Hyperfine Interaction In Crystalline Cdo, David C. Look Aug 1969

Nmr Determination Of The Conduction-Electron Hyperfine Interaction In Crystalline Cdo, David C. Look

Physics Faculty Publications

Measurements of the Cd113 nuclear-spin-lattice relaxation time T1 and Hall effect in crystalline CdO, a degenerate semiconductor, have yielded the contact hyperfine strength of the conduction electrons at the nuclei. The product T1T=168 sec °K, independent of temperature T and frequency ν for T=1.4,4.2, and 77-350 °K, and for ν=2-10 MHz. Taking the carrier concentration N=2.6×1019 cm-3 independent of temperature to within 3% at 4.2, 77, and 300°K, and using an effective electron mass me*=0.2me, we calculate an averaged electron probability density at the nucleus, 〈|φF(0)|2 …

Go to article

Angular Correlation Of Positron Annihilation Radiation In Damaged Nickel And Iron, Hsien Chen Huang Aug 1969

Angular Correlation Of Positron Annihilation Radiation In Damaged Nickel And Iron, Hsien Chen Huang

Masters Theses

No abstract provided.

Go to article

Inelastic Deuteron Scattering From 151Eu, Gerald Ralph Boss Aug 1969

Inelastic Deuteron Scattering From 151Eu, Gerald Ralph Boss

Masters Theses

No abstract provided.

Go to article

The Elastic Scattering Of 1.33 Mev Gamma Rays From Tin, J. Edward Terdal Aug 1969

The Elastic Scattering Of 1.33 Mev Gamma Rays From Tin, J. Edward Terdal

Masters Theses

No abstract provided.

Go to article

The Mossbauer Effect In Ferric Stearate And Ferric Oleate, Ronald L. Wilson Aug 1969

The Mossbauer Effect In Ferric Stearate And Ferric Oleate, Ronald L. Wilson

Masters Theses

No abstract provided.

Go to article

Standing Waves On The Moon, Lewis T. Chadderton, Frans G. Krajenbrink, Robert Katz, Arcadio Poveda Jul 1969

Standing Waves On The Moon, Lewis T. Chadderton, Frans G. Krajenbrink, Robert Katz, Arcadio Poveda

Robert Katz Publications

The existence of local annular and radial structures in the environment of lunar craters, and of a global selenographic tectonic pattern, is ascribed in part to standing “moonquakes” established after impact or eruption.

Go to article

A Calculation Of Photodetachment From Molecular Oxygen, Raymond Pollock Jr. Jul 1969

A Calculation Of Photodetachment From Molecular Oxygen, Raymond Pollock Jr.

Physics & Astronomy ETDs

The problem of photodetachment from homonuclear diatomic mole­cules is treated theoretically, with the aim of providing a calcula­tion of photodetacbment from the molecular oxygen ion. Using a two­-center (spheroidal) coordinate system a one-electron model including direct coulomb, polarization, and approximate exchange interactions is developed, and formulas for scattering and photodetachment cross section are derived. Wave functions representing both bound and free electrons in the field of the neutral molecule are calculated numerically, using adjustable parameters in the exchange and polarization potentials to attain the proper binding energy. The photodetachment cross section is then computed from these wave functions, along with …

Go to article

An Attempt To Measure The Diffusion Of Aluminum Into Natural Aluminum Oxide, Charles Edward Galaspie Jul 1969

An Attempt To Measure The Diffusion Of Aluminum Into Natural Aluminum Oxide, Charles Edward Galaspie

Master's Theses

The goal of this research was to investigate the diffusion of aluminum ions in natural aluminum oxide grown under atmospheric conditions. The basis for the approach employed here had been developed earlier by J. H. Christian and H. L.Taylor. However, these authors studied the diffusion of aluminum ions in an oxide grown in a pure oxy­gen atmosphere. They utilized a glass slide upon which aluminum metal was deposited in vacuo (10-11 Torr). Oxide was then allowed to grow on this metal by back-filling the vacuum with pure oxygen to a pressure of 40 to 50 m Torr while infrared …

Go to article

Decay Of The (2S22P)2P Compound State In Helium By Two-Electron Emission, Paul Burrow, G.J. Schulz Jun 1969

Decay Of The (2S22P)2P Compound State In Helium By Two-Electron Emission, Paul Burrow, G.J. Schulz

Paul Burrow Publications

Compound states of atoms are known to decay by the emission of a single electron into many states lying at lower energies. Compound states associated with doubly excited states lie at energies above the ionization potential, and therefore the decay into an ion by the emission of two electrons is energetically possible. This paper presents evidence for such a two-electron decay in the case of the (2s22p)2p compound state of helium which derives from the (2s2)1S atomic state.

Go to article

Spectrophotometric System For Transient Observation Of Solids Under Pulsed Electron Irradiation, R.T. Williams, Robert Fuller, M.N. Kabler, V.H. Ritz Jun 1969

Spectrophotometric System For Transient Observation Of Solids Under Pulsed Electron Irradiation, R.T. Williams, Robert Fuller, M.N. Kabler, V.H. Ritz

Robert G. Fuller Publications

THE purpose of this note is to describe a relatively simple apparatus for measuring the properties of transient optical absorption and emission bands in solids under pulsed irradiation. The equipment is presently being for the electron beam. The electron beam traverses a 28 cm air path between the exit window of the electron accelerator and the titanium Dewar window. The sample is mounted in vacuum on the Dewar cold finger approximately 3 cm behind the Dewar window. Under these conditions a single electron pulse will deposit 1017 eV/cm2 in the sample. This generates an easily detected transient absorption …

Go to article

High-Field Galvanomagnetic Properties Of Aual2, Auga2, And Auin2, J.T. Longo, P.A. Schroeder, David J. Sellmyer Jun 1969

High-Field Galvanomagnetic Properties Of Aual2, Auga2, And Auin2, J.T. Longo, P.A. Schroeder, David J. Sellmyer

David Sellmyer Publications

Measurements of the magnetoresistance and Hall voltage have been made in the high-field region on the metallic fluorite compounds AuAl2, AuGa2, and AuIn2. The results have been compared with those expected from the nearly-free-electron (NFE) model. These compounds are uncompensated. The magnetoresistance measurements in principal planes and directions, with one exception, support the NFE model, but the dimensions of the two-dimensional areas of aperiodic open orbits show pronounced deviations. Hall-effect measurements for B in the 〈100〉 and 〈111〉 directions indicate significant departures of the real Fermi surface from the NFE model. A proposed empirical …

Go to article

Electrical Conductivity & Seebeck Effect In Activated Molybdenum Oxide Hydrogen Detectors, John Hooker Jun 1969

Electrical Conductivity & Seebeck Effect In Activated Molybdenum Oxide Hydrogen Detectors, John Hooker

Masters Theses & Specialist Projects

This thesis describes the results and analysis of Seebeck coefficient and electrical conductivity measurements on "activated", molybdenum-oxide, thin film hydrogensensing elements. The work was undertaken in an effort to produce data that would be useful in obtaining an understanding of the electronic processes which cause large electrical conductivity changes in molybdenum-oxide upon exposure to small concentrations of hydrogen in air. The results are analyzed using a simple band model of a semiconductor. This model is shown to give reasonable results at high temperatures; however, a departure from the usual .! model is required in order to explain the results at …

Go to article

A Nonsecond Time-Of-Flight Spectometer, David Moorman Jun 1969

A Nonsecond Time-Of-Flight Spectometer, David Moorman

Masters Theses & Specialist Projects

The purpose of this thesis was to construct a time-of-flight spectrometer using plastic scintillators coupled to photomultiplier tubes as the primary detectors. A time-of-flight spectrometer with at least 2.0 nanoseconds of time resolution was desired.

Go to article

L And M Auger Spectra For Silver, Samaa Naga El Ibyari May 1969

L And M Auger Spectra For Silver, Samaa Naga El Ibyari

Archived Theses and Dissertations

No abstract provided.

Go to article

Directional Correlation Of The 346-136 Kev Gamma-Gamma Cascade In Ta¹⁸¹, Robert Allan Wilson May 1969

Directional Correlation Of The 346-136 Kev Gamma-Gamma Cascade In Ta¹⁸¹, Robert Allan Wilson

Dissertations and Theses

The directional correlation of the 346-136 Kev gamma-gamma cascade in Ta¹⁸¹ was measured using the delayed coincidence method with a source of Hf¹⁸¹ in 27 N HF. The contributions to the composite delayed coincidence spectrum of the interfering 133-482 Kev and 133-346 Kev cascades were removed by the subtraction from this spectrum of appropriate 133-482 Kev pure delayed coincidence data. The extracted 346-136 Kev coincidence data then yielded the correlation coefficients A₂₂ = 0.190±0.011 and A₄₄. = -0.025±0.024 that are consistent with the established spin sequence 5/2(E2)9/2(M1 + E2)7/2 and with an admixture of 16.2%±1. 2% E2 radiation in the …

Go to article

The Monte Carlo Method Applied To An Estimation Of Delayed Neutron Response, Garland David Turner May 1969

The Monte Carlo Method Applied To An Estimation Of Delayed Neutron Response, Garland David Turner

Physics & Astronomy ETDs

An experimental program has been undertaken at Los Alamos Scientific Laboratory to study delayed neutron effects. As a part of this program, experiments were conducted with thin disks of various fissionable materials to measure the delayed neutron response to a pulse of high-energy neutrons. In support of the experiments, calculations were made with a computer program which solves the Boltzmann transport equation by finite difference methods. Difficulties with the calculations led to an analysis showing that correct treatment of neutrons moving parallel to the faces of the disk was vital to the success of the calculation. As an extension of …

Go to article

Lattice Dynamics Of Naf, Arnold Karo, John R. Hardy May 1969

Lattice Dynamics Of Naf, Arnold Karo, John R. Hardy

John R. Hardy Papers

The results of an extended calculation of the normal modes of the NaF lattice are presented. Three models have been considered : a "rigid-ion" (RI) model, a "deformation-dipole" model with central F--F- short- range interactions (DDNNN), and a “deformation-dipole" model including both central F--F- interactions and a noncentral component in the first-neighbor, short-range interactions [DDNNN(NC)]. For each of these models we have derived frequency spectra for both 300 and 0°K input parameters, the associated dispersion curves for symmetry directions, Debye characteristic temperatures ΘD, moment functions ωD(n), and the …

Go to article

High-Field Studies Of Band Ferromagnetism In Fe And Ni By Mössbauer And Magnetic Moment Measurements, S. Foner, A. J. Freeman, N. A. Blum, Richard B. Frankel, E. J. Mcniff, Jr., H. C. Praddaude May 1969

High-Field Studies Of Band Ferromagnetism In Fe And Ni By Mössbauer And Magnetic Moment Measurements, S. Foner, A. J. Freeman, N. A. Blum, Richard B. Frankel, E. J. Mcniff, Jr., H. C. Praddaude

Physics

High-field susceptibility χHF in Fe and Ni (at 4.2, 77, and 300°K) and high-field Mössbauer studies in Fe at 4.2°K are reported and related to the band structure of Fe and Ni and to band models of ferromagnetism. The Mössbauer effect was employed to measure the change in the hyperfine field Hn at the 57Fe nucleus with application of an external field. Assuming Hn to be proportional to the bulk magnetization, a microscopic equivalent to χHF is obtained. We also show how the high-field data may be used alternatively to determine the nuclear g factor. …

Go to article

Theoretical Investigations Of The Vibrational Spectra Of Boron Oxide Glass, Zaven K. Altounian May 1969

Theoretical Investigations Of The Vibrational Spectra Of Boron Oxide Glass, Zaven K. Altounian

Archived Theses and Dissertations

No abstract provided.

Go to article

First Prev Next Last