Physics

Formation Of Carbides On Tungsten Wires, W. J. Croft, Kaare J. Nygaard

Physics Faculty Research & Creative Works

It has been found that layers of tungsten carbide form on tungsten wires processed under ultra-high vacuum. The carbide is formed from carbon impurities in the volume of material.

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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 …

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

Masters Theses

No abstract provided.

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A Heavy-Ion Energy Loss Spectrometer, John T. Park, F. D. Schowengerdt

Physics Faculty Research & Creative Works

A high-resolution system for the measurement of the energy loss spectra of 20-250 keV heavy ions incident on gas targets is described. The high resolution is obtained by decelerating the ion beam to a low, well-defined energy before performing the energy analysis. The energy loss spectrum is determined by changing the accelerator energy to compensate for energy lost in collisions with the gas atoms. The system is arranged so that normal fluctuations in the accelerator's power supply do not affect the energy resolution. The resolving power of the system is 2.5x104. The primary proton beam has a detected WHM of …

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Heavy-Particle Energy-Loss Spectrometry: Inelastic Cross Sections For Protons Incident Upon Helium, John T. Park, F. D. Schowengerdt

Physics Faculty Research & Creative Works

A method is described whereby absolute cross sections are obtained from inelastic energy-loss spectra induced by ions incident upon gaseous targets at energies of 25-125 keV. Inelastic energy-loss spectra of helium for proton impact are presented. Apparent differential cross sections and absolute total cross sections are obtained from the spectra. Total cross sections for the sum of the 1S1→2S1 and 1S1→2P1 excitations are reported, along with estimates of the relative contributions of each. Total ionization cross sections, total cross sections for inelastic scattering, apparent energy distributions of ejected electrons, and partial ionic stopping powers are also reported. The excitation cross …

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Charge-Transfer Cross Sections For Negative Ions On Atomic And Molecular Targets, W. (William) R. Snow, R. D. Rundel, R. Geballe

Physics Faculty Research & Creative Works

Charge-transfer cross sections for H^- on O, O₂, and NO₂; O^- on H, O, H₂, O₂, and NO₂; and C^- on H and O have been measured over an energy range of 0.5 to 4 keV using a modulated crossed-beam apparatus. The experimental cross sections are compared with theories of resonant and non-resonant charge transfer based on a two-state approximation. For the reactions H^-+O O^-+H, the cross sections are found to be consistent with detailed balancing. The effect of electron detachment on charge-transfer …

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Some New Approaches To Shallow Impurity States, Wayne E. Tefft, Robert John Bell, Harold V. Romero

Physics Faculty Research & Creative Works

A variational calculation of shallow surface impurity states including image-charge and anisotropic mass effects was performed using two different sets of orthogonal functions. The first set was obtained by varying the Bohr radius in the hydrogenic functions, separately for each state. In the second set the Bohr radius was allowed to become anisotropic, and the elements were separately treated as variational parameters. In each case it was shown that with certain restrictions on the variational parameters the set remained complete and orthogonal. General expressions for the energy eigenvalues for both the bulk and surface problem obtained from the first set …

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Entropy Of The Mixed State Of Some Low-Κ Type-Ii Superconductors, Don Carlos Hopkins, R. R. Rice, J. M. Carter, J. D. Hayes

Physics Faculty Research & Creative Works

The entropy of the mixed state of type-II superconductors with low κ(∼1) is studied for the alloys Pb_0.96Tl_0.04 and In_0.88Sn_0.12. The current theories are reviewed for approximations valid near Hc1 and near Hc2. The experiments show for the most reversible sample (Pb_0.96Tl_0.04) that (SB)_T of the mixed state depends only on temperature, and that (ST)_B increases linearly with B from its value for the superconducting state until it drops discontinuously to its normal state value at H_c2. There is no abrupt increase in the specific …

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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 …

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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 …

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

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.

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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.

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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 T_c 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.

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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.

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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 …

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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 …

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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.

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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 m_e^*=0.2m_e, we calculate an averaged electron probability density at the nucleus, 〈|φ_F(0)|^{2 …}

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Inelastic Deuteron Scattering From 151Eu, Gerald Ralph Boss

Masters Theses

No abstract provided.

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

Masters Theses

No abstract provided.

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

Masters Theses

No abstract provided.

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

Masters Theses

No abstract provided.

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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.

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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 …

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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 …

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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.

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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 …

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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 …

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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.

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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 …

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Full-Text Articles in Physics

Formation Of Carbides On Tungsten Wires, W. J. Croft, Kaare J. Nygaard

Physics Faculty Research & Creative Works

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

Physics Faculty Research & Creative Works

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

Masters Theses

A Heavy-Ion Energy Loss Spectrometer, John T. Park, F. D. Schowengerdt

Physics Faculty Research & Creative Works

Heavy-Particle Energy-Loss Spectrometry: Inelastic Cross Sections For Protons Incident Upon Helium, John T. Park, F. D. Schowengerdt

Physics Faculty Research & Creative Works

Charge-Transfer Cross Sections For Negative Ions On Atomic And Molecular Targets, W. (William) R. Snow, R. D. Rundel, R. Geballe

Physics Faculty Research & Creative Works

Some New Approaches To Shallow Impurity States, Wayne E. Tefft, Robert John Bell, Harold V. Romero

Physics Faculty Research & Creative Works

Entropy Of The Mixed State Of Some Low-Κ Type-Ii Superconductors, Don Carlos Hopkins, R. R. Rice, J. M. Carter, J. D. Hayes

Physics Faculty Research & Creative Works

Nuclear Structure Studies In 90Y, Ronald E. Goans

Masters Theses

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

Paul Burrow Publications

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

Physics

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

All Physics Faculty Publications

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

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

Physics

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

Robert Katz Publications

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

David Sellmyer Publications

11th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

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

Physics Faculty Publications

Inelastic Deuteron Scattering From 151Eu, Gerald Ralph Boss

Masters Theses

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

Masters Theses

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

Masters Theses

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

Masters Theses

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

Robert Katz Publications

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

Physics & Astronomy ETDs

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

Master's Theses

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

Paul Burrow Publications

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

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

David Sellmyer Publications

A Nonsecond Time-Of-Flight Spectometer, David Moorman

Masters Theses & Specialist Projects

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

Masters Theses & Specialist Projects