Digital Commons Network^™

Linear Pulsation Analysis Of Cluster Cepheid Variables, Charles E. Needham

Physics & Astronomy ETDs

Models for thirteen classical Cepheids found in galactic clusters or associations are analyzed. The models are calculated using the most recently published photometric data and theoretical evolutionary tracks. The linearized equations of mass, momentum and energy conservation are solved subject to an infinitesimal radial perturbation of each equilibrium model. The equations are first solved in the adiabatic approximation. This solution is then used as the initial value for the iterative solution of the non-adiabatic equations. The linearized analysis provides information on pulsation periods of fundamental and harmonic modes, stability against pulsations and phase differences between various physical parameters, such as …

Ion‐Pair Theory Of Concentrated Electrolytes. Iii. Variational Principle, Frank Stillinger, Ronald White

Center for Advanced Mineral and Metallurgical Processing (CAMP)

Two major contributions are devised for that theory of concentrated electrolytes which by convention regards the ions as completely paired into uncharged dipolar “molecules.” First, a more satisfactory expression is obtained for the wavelength‐dependent static dielectric “constant” ε(k). Second, a variational principle for Helmholtz free energy F is displayed whose minimization with respect to the ion‐pair size distribution p(1) serves to determine both F and p(1). In anticipation of future numerical applications, a binary collision approximation is specified for the short‐range interaction aspect of the functional F[p(1)].

Ion‐Pair Theory Of Concentrated Electrolytes. Iv. Ion Atmosphere Charge Distribution, Frank Stillinger, Ronald White

Center for Advanced Mineral and Metallurgical Processing (CAMP)

Arguments are presented indicating that the large‐size limiting behavior of the ion‐pair size distribution is qualitatively the same both with, and without, Coulomb interactions between ions. This in turn implies that the static dielectric response function ε0 / ε(k) derived in the preceding paper is nonanalytic at k = 0. The specific singular behavior of this response requires a branch cut along the imaginary k axis. It furthermore induces an r−8 tail in the ion atmosphere charge distribution at finite electrolyte concentration.

Hydrostatic Pressure Effects On The Epr Spectrum Of V2+:Al203, Jonathan Lloyd Albain

Masters Theses

No abstract provided.

Construction Of A Small Vacuum Ultraviolet Spectrograph, Dale A. Eding

Masters Theses

No abstract provided.

Spectroscopic Measurement Of The Electron Temperature In The Tenuous Argon Ion Laser Plasma, Dane Danijel Bicanic

Physics Theses & Dissertations

The validity of the line intensity ratio technique for measuring the electron temperature was examined for an argon plasma with a "population inversion" i.e., the number of ions with electrons in the upper 4p levels was greater than in the lower 4s levels. The line intensities from these levels, the argon ion lasing transitions, were measured in a pulsed tenuous plasma at 110μ Hg produced by discharging a capacitor through a tube 2m long and 7mm inside diameter. The electron impact cross sections for simultaneous excitation and ionization as measured by Latimer and St. John were used and averaged over …

An Experimental Investigation Of The Vortex Sink Rate Sensors, Nelson L. Lu

Mechanical & Aerospace Engineering Theses & Dissertations

The vortex sink rate sensor device consists basically of an ideal sink flow between two coaxial disks. A sink tube was located at the center of one disk. The vortex was created by the rotation of the unit about its axis of symmetry. Five inch and 10 inch diameter of porous couplers were used for the air chamber here in this investigation. Several slenderness parameters, i.e., the ratio of the sink tube diameter to the height of the air chamber ^ro/n were conducted. Two probes were used to measure the static pressure and stagnation pressure respectively at various positions …

Length And Velocity Formulas In Approximate Oscillator-Strength Calculations, Anthony F. Starace

Anthony F. Starace Publications

The matrix element for electric dipole transitions is correctly given by the length formula in the Hartree-Fock, configuration-interaction, and related approximations, which involve the diagonalization of an approximate, but nonlocal, Hamiltonian.

Lorentz-Invariant And Lorentz-Noninvariant Approximation Techniques In The Spin-Parity Analysis Of Four-Pion Resonances, Wilson C. Lu

Masters Theses

No abstract provided.

Mössbauer Spectroscopy Study Of The Spin‐Flop Transition In Fe‐Doped Mnf2, C. R. Abeledo, Richard B. Frankel, A. Misetich, N. A. Blum

Physics

Measurements of the hyperfine interaction in Fe^{+ +} in MnF₂ in external fields above the spin‐flop field at 4.2 K are reported and a value of g⊥ = 2.13 is derived, in good agreement with theory.

Track Theory And Radiation Quality, Robert Katz

Robert Katz Publications

Radiation detection and damage data from several physical, chemical, and biological systems have been analyzed by a unified track theory, in which observed effects are attributed to the interaction of secondary electrons with the medium. Gamma-ray dose-response curves are combined with calculations of the spatial dose distribution about an ion's path to yield dose-response curves (survival curves) for heavy ion bombardment, through appropriately defined parameters. Perplexing phenomena associated with high LET radiation are sorted out according to track regime (grain-count or track-width), inactivation mode (gamma-kill or ion-kill), structural complexity (elementary, cellular, multicellular), and end-point. The central problem in assigning a …

Mössbauer Effect In Fe-Doped Kmgf3, J. Chappert, J. R. Regnard, Richard B. Frankel, A. Misetich, N. A. Blum

Physics

An iron-doped KMgF₃ single crystal has been studied with the Mössbauer technique. The two charge states, Fe²⁺ and Fe³⁺, are observed. Below 12 °K an Fe²⁺ quadrupole doublet appears. Using Ham strain model we calculate that the first excited spin-orbit level lies ~ 120 cm^-1 above the Γ_5g ground state.

Low-Lying Even-Parity Resonances In Ki:Ag+, Roger D. Kirby

Roger Kirby Publications

Lattice resonances of E_g symmetry (16.35 cm^-1) and A_1g symmetry (25 cm^-1) have been found in KI:Ag⁺ using far-infrared spectroscopic techniques. The two even-parity modes are found to be anharmonically coupled to the T_1u^- symmetry resonant mode at 17.3 cm^-1, giving rise to the combination bands observed at 30 and 44.4 cm^-1.

Isomeric Shift Of The 83 Kev Transition In 153Eu, E. Ansaldo, L. Grodzins, Richard B. Frankel

Physics

No abstract provided.

Far-Infrared Properties Of Lattice Resonant Modes. V. Second-Order Stark Effect, B.P. Clayman, Roger D. Kirby, A. J. Sievers

Roger Kirby Publications

Small electric-field-induced frequency shifts have been observed for resonant modes associated with three defect systems. For NaI: Clˉ, the shifts have been used to measure the quartic anharmonic terms of the interionic potential of the impurity ion. For KBr: Li⁺, the quartic anharmonic terms are found to be very small, and an harmonic potential which includes a central barrier with the barrier height less than the zero-point energy of the oscillator is required to explain the experimental results. For NaCl: Cu⁺, only an "on-center" resonant-mode configuration is consistent with the experimental results.

Lamb-Mössbauer Factor Of Sodium Ferrocyanide, Daniel L. Decker, L. E. Lortz

Faculty Publications

Using a set of commercially prepared sodium ferrocyanide absorbers enriched to 91.2% Fe57 the Lamb-Mössbauer factor was measured to be 0.28±0.03. The thickness of Fe57 for these absorbers was measured using x-ray absorption techniques and was found to be considerably smaller than that advertised by the manufacturer even after correcting for the size of the ferrocyanide particles in the absorbers.

Dielectric Polarization And Alignment And The Structure Of Polar Fluids, John D. Ramshaw, D. W. Schaefer, John S. Waugh, J. M. Deutsch

Physics Faculty Publications and Presentations

An analysis is made of the information about the structure of dense polar fluids which resides in the dielectric constant, the Kerr constant, and the nuclear magnetic resonance (NMR) quadratic electric field effect. The inadequacy of the "local-field" model for liquids is discussed. The existence of a nonzero molecular hyperpolarizability is shown to destroy an equivalence which would otherwise exist between the Kerr and NMR experiments, and can easily account for apparent discrepancies between the reported Kerr and NMR data for nitrobenzene and nitromethane. A method is presented for removing dielectric boundary effects from statistical averages, so that the averages …

Simulation Of Particle Tracks In Emulsion, Thomas E. Furtak, Robert Katz

Robert Katz Publications

Micrographs of energetic particles in nuclear emulsion are simulated by computing the spatial distribution of developed grains with the δ-ray theory of track structure, and representing the developed grains by points of light on an IBM 2250 visual display unit. The simulated tracks display many of the features of actual track structure and serve as a visual comparison between experiment and theory,

A Vibrational And Rotational Analysis Of Eight Simple Models Of The Hydrogen Molecule In The Ground State., Stuart Fleming Hayes

Physics & Astronomy ETDs

The object of this dissertation was the investigation of the influence on the delta G curve for H2 of polarization, enhancement of charge between the nuclei, and variation of the screening parameter. A better understanding of the influence of these factors could lead to progress in estimating more accurately the dissociation energies of diatomic molecules. Also to be investigated was the correlation between these factors and the vibrational and rotational spectroscopic constants, particularly Bv.

The Heitler-London combination of atomic orbitals (referred to as phi 1) was used in every wave function The atomic orbital 2pz was used in phi 2 …

A Variable Coeficient Of Restitution Experiment On A Linear Air Track, R. Gruebel, James C. Dennis, L. Choate

Faculty Publications

A system consisting of two pendula attached to an air cart is mathematically analyzed, and the coefficient of restitution is shown to pass through a deep minimum. The solution to the small angle equation of motion is transcendental and provides an exercise in graphical methods for the beginning mechanics student.

The Impulse And Doublet, Richard C. Heyser

Unpublished Writings

The basic problem to which this paper is directed is that of characterization of the acoustic field perceived by an observer and due to a loudspeaker situation in a room. Before immediately jumping into an apparent solution and presenting the results of a set of measurements it is essential to present the considerations leading to that measurment...First, there are at least two ways of characterizing the same acoustic signal if we restrict our attention to a well defined set of parameters...Secondly, since both characterizations define the same thing it must be possible to translate information without loss from one domain …

Observation Of Quadrupole Splitting Of B-12 In A Single Crystal, R. L. Williams Jr., Richard C. Haskell, Leon Madansky

All HMC Faculty Publications and Research

The quadrupole coupling of B-12 implanted in Be-9 has been observed using a single crystal of Be. One sees a narrow resonance line, the location of which depends in the normal way on the orientation of the crystalline c-axis with respect to the external magnetic field direction. The coupling constant is given by e2qQ/h = 54.9(6) kHz. This is consistent with our previous measurement using a Be foil. Using the field gradient at Be-9 lattice sites, calculated by Pomerantz and Das, one finds Q(B-12) = about 34.6 mb.

Properties Of The Interstitial In The Diamond-Type Lattice, G D. Watkins, R P. Messmer, C Weigel, David Peak, J W. Corbett

All Physics Faculty Publications

Linear combination of atomic orbital—molecular orbital cluster calculations using extended Hückel theory suggest that the interstitial carbon atom in diamond prefers an "interstitialcy" configuration. The predicted minimum-energy configuration changes with charge state, providing a possible example of the Bourgoin mechanism for "athermal" migration of the interstitial in the presence of ionizing radiation.

Angular And Energy Distribution Of Cross Sections For Electron Production By 50-300-Kev-Proton Impacts On N2, O2, Ne, And Ar, J. B. Crooks, M. Eugene Rudd

M. Eugene Rudd Publications

Cross sections differential in angle and ejection energy for electron production by proton impact on nitrogen, oxygen, neon, and argon have been measured using electrostatic analysis and counting of individual electrons. The range of proton energies was 50-300 keV, the angles ranged from 10° to 160°, and the electron energies were measured from 1.5 to 1057 eV. Integrations over angle and/or electron energy yielded singly differential and total electron production cross sections. Our total cross sections for oxygen fall halfway between previous data of deHeer et al. and Hooper et al., but our argon cross sections agree better with deHeer …

Recent Meetings-Nebraska Section, Robert Fuller

Robert G. Fuller Publications

The fall meeting of the Nebraska Section of the AAPT was held 31 October 1970 at the University of Nebraska in Lincoln. The sessions were chaired by Professor Clyde Sachtleben, Hastings College.

Measurement Of Nuclear Magnetic Dipole Moment Of Li-8 By Implantation In Metal Foils, Richard C. Haskell, R. L. Williams Jr., Leon Madansky

All HMC Faculty Publications and Research

Polarized 8Li nuclei have been produced through the 7Li(d,p) reaction using the 3.5-MeV Van de Graaff accelerator at Brookhaven National Laboratory. The observed polarization was a slowly-varying function of deuteron energy over the range 1.3-2.9 MeV, reaching a maximum of about +1.6%. The recoiling nuclei were stopped in Au, Pt and Pd foils and the effective dipole moments were measured by a resonant depolarization method. The results were 1.65362(22)µN, 1.65288(20)µN and 1.65270(30)µN respectively. These are consistent with the work of Connor, who found µ(8Li) =1.6530(8)µN in a LiF crystal. An upper limit for the 8Li quadrupole moment will also be …

Mossbauer Study Of An Intramolecular Antiferromagnet, R. Lechan, C. R. Abeledo, R. B. Frankel

Physics

Mossbauer measurements at 4.2 ≤T ≤ 22 K and OsHosBO kOe are + reported in (Fe Salen Cl)₂, a molecular complex containing two coupled Fe³⁺ ions bridged by oxygen atoms. At 4.2 K only the ground state with effective spin S = 0 is appreciably populated. Analysis of the magnetic field and temperature dependence of the magnetic hyperfine field yields an exchange constant J= -6.7 cm>sup>-1 and a hyperfine field of -192 kOe per unit spin at each Fe³⁺ nucleus.

MöSsbauer Studies Of Stable Interstitial And Substitutional Sites Of Cobalt In Gold, Charles Freeland Steen

Dissertations and Theses

Precision measurements of the Debye-Waller factor of Fe⁵⁷ in Au using the wide black absorber technique have been made in the temperature range from room temperature to 830 K. The major source of error arises from Au L_y x-rays which are unresolved by the radiation detection system from the 14.4 KeV gamma ray. The K absorption edge of Br has been used to correct for the presence of x-rays.

These measurements have revealed the existence of two nonequivalent lattice sites which the Co⁵⁷ impurity (parent of Fe⁵⁷) may occupy. One of the sites has been …

Photoionization Of Photoexcited Cesium, Robert E. Hebner

Doctoral Dissertations

"A new method for obtaining the cross section for photoionization of photoexcited cesium is presented. The salient feature of this experiment is to use three crossed beams, i.e., two light beams intersecting a beam of cesium atoms. The cross section is determined by counting the ions produced by the two step process: Cs (6S) + h[upsilon]₁ --> Cs (6P) ; Cs (6P) + [upsilon]₂ --> Cs⁺ + e⁻ The relative cross section for the second step has been obtained from threshold (5060 Å) to 2500 Å. The excitation light source used in obtaining this cross section was a rf resonance …

Local Magnetic Moments And The Mossbauer Effect, Richard B. Frankel, Brian B. Schwartz

Physics

No abstract provided.