Physics Commons^™

Time-Dependent Ionization Equilibrium And Line Radiation Under Flarelike Conditions, Menas Kafatos, W. H. Tucker

Mathematics, Physics, and Computer Science Faculty Articles and Research

The results of calculations for time-dependent ionization equilibrium and line emission are presented and compared with the values obtained under the assumption that steady-state conditions prevail. In the models considered, it is assumed that the electron density is constant (=10^3 cm^-3) and that the temperature increases by a factor of 10 from 3 x 10^6 K on timescales ranging from 100 to 300 s and decays back to 3 x 10^6 K on a timescale ranging from 600 to 1400 s. Ions of oxygen and silicon are considered, and it is found that the spectrum is softer during the rise …

Evidence For The Existence Of Two Stable Sites For Cobalt Impurity Atoms In Aluminum, Arun Venkatachar

Dissertations and Theses

Using Fe⁵⁷Mössbauer spectroscopy, two alternative sites occupied by cobalt (10^-4 at. % ) impurity atoms in aluminum have been isolated. The substitutional site A is the stable position after annealing the sample above 840 K, followed by a rapid quench. The impurity atoms in site A are characterized by a single line Mössbauer spectrum (indicative of a cubic environment), a room-temperature f = 0.502 (r. m. s. displ. 0.071 A) and an I. S. (reI. to Fe) = -0.421 mm/sec. For anneals below 770 K the cobalt atoms migrate to site B, which is characterized by a …

Crystal Structure Determination Of Β-Lactoglobulin From Electron Micrographs, Richard Roeter

Dissertations and Theses

Often electron micrographs exhibit a repeating structure. Sometimes this repeating structure satisfies the definition of a crystal in that it has a three dimensional repeating structure. If the unit cell structure of this repeating structure can be determined it can be used to help categorize different sections of a particular sample. In some cases, the use of optical diffraction analysis of electron micrographs with repeating structure is a method of determining the unit cell structure.

Samples of β-Lactoglobulin were prepared for viewing in the electron microscope using both the crystalline material and carbon replicas of the crystal surface. Because the …

Radiation Induced Color Centers In Potassium Silicate Glasses Containing Lead, Ibrahim Abou-Seif Henry

Archived Theses and Dissertations

No abstract provided.

Some A. C. Properties Of Lead-Borate Glasses, Salah El-Din El-Nahwy

Archived Theses and Dissertations

No abstract provided.

Radiation Induced Color Centers In Alkali Silicate Glasses, Ramez Morgan Louca

Archived Theses and Dissertations

No abstract provided.

On The Interaction Of Aluminium And Iron Calcium Borate Glasses And Its Effect On The Properties Of Their Composites, Sherif K. Arif

Archived Theses and Dissertations

No abstract provided.

Electron Optical Study Of A Secondary Electron Multiplier, Chang Min Shen

Dissertations and Theses

Electron orbital theory was applied to the design of the geometrical structure of an electron multiplier for an image intensifier. A special structure satisfying production requirements was studied. Electron optical calculations consisted of determining the potential distribution and tracing the electron trajectories. Liebmann's procedure was used to solve Laplace's equation with constant potentials on the multiplier electrodes as boundary conditions. The trajectories were determined by solving the equation of motion in an electrostatic field using a Runge-Kutta procedure. The initial conditions for the trajectories were the initial energies, initial positions, and the initial directions of the secondary electrons. The plotted …

An Investigation Of A Gas Measurement Technique Employing Ultraviolet Excitation, Alphonso Vincent Diaz

Physics Theses & Dissertations

A study was undertaken to determine the general applicability of a temperature measurement technique which uses the fluorescence stimulated by a vacuum ultraviolet continuum as the indicator. This study was directed toward determining the temperature of nonradiating carbon monoxide. A number of ultraviolet radiation sources which produced high intensity in the region of l,150 A were investigated. This study led to the conclusion that the technique was not applicable to measurements in carbon monoxide within the present limits of' detectability.

Investigation Of The Alpha-Sub-Gamma Phase In Alnico 6, Cortez Samuel

Dissertations and Theses

The purpose of this research project was to study the αᵧ phase in Alnico 6. Other phases were studies for comparison. Also the effect of an applied magnetic field on the formation of the αᵧ phase was investigated.

Three single crystals of Alnico 6 were heat treated for one hour—one at 1250°C, one at 1000°C, and one at 800°C—and water-quenched. The microstructure of each sample was observed with the optical microscope, and X-ray diffraction patterns were taken to determine the crystal structure of the phases present.

Several single crystal samples of Alnico 6 were heat treated at 1000°C and furnace-cooled. …

Excitation Of Hydrogen Atoms By Fast Protons, Edward Ellis Fitchard

Physics Theses & Dissertations

In this thesis a theoretical study is made of excitation of hydrogenic atom by charged particles such as protons or electrons. The approximation to the cross section for an inelastic scattering process is obtained under the following radically simplifying assumptions. The projectile is represented in its initial and final state by plane waves. All distortions are neglected whether they originate in an inelastic process or an elastic deflections of the charged particle by the nucleus. The perturbation of the atomic orbits between which the projectile induces transitions is neglected. Nonrelativistic hydrogenic wave functions are used for the electronic states. In …

Ionic Polishing Of Fused Silica And Glass, Raymond Wilson

Raymond Wilson

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

Archived Theses and Dissertations

No abstract provided.

Analysis Of The Vibrational Modes Of The Triborate Anion, Panayiotis Th. D. Sphicas

Archived Theses and Dissertations

No abstract provided.

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

Archived Theses and Dissertations

No abstract provided.

Polarization Of Compton-Scattered Gamma Rays, James G. Hudson

Honors Theses

Intermediate energy photons (approximately 0.2 mev. to 10 mev.) interact with matter of low atomic number principally through a process called the Compton effect. This process is an inelastic collision of a photon with a free electron at rest. Using the principles of conservation of energy and conservation of momentum the energy of the scattered photon can be found in terms of the incident photon energy and the angle through which it is scattered. The energy of this scattered photon is then given by E¹=(E_O)/(1+α(1-cos θ)) where E_O is the energy of the incoming photon, …

Molecular Vibrations Of Tetrahedral Systems With Application To Fused Silica, Leila Sado Balloomal

Archived Theses and Dissertations

No abstract provided.

A Study Of Aluminium-Lead Borate Glass Composite Materials, Aziza Nour El-Din Ragai

Archived Theses and Dissertations

No abstract provided.

Measurements Of Stark Widths Of Argon Ion Lines, Nelson Wayne Jalufka

Dissertations, Theses, and Masters Projects

No abstract provided.

X-Ray Diffraction And Electron Microscopy Studies Of Glasses Containing Antimony, Sadek Momtaz Tadross

Archived Theses and Dissertations

No abstract provided.

Design And Construction Of A Pulsed Glass Laser, Mostafa Ibrahim Azab

Archived Theses and Dissertations

No abstract provided.

Radiation Damage Studies Of Libyan Desert Silica Glass, Farkhonda Hassan

Archived Theses and Dissertations

No abstract provided.

Frederic Joliot-Curie And Atomic Energy By Pierre Biquard Pp. 109-211, Donald Printest Watkins

Honors Theses

This is a translation of pages 109-211 of the biography Frederic Joliot-Curie Et L'energie Atomique by Pierre Biquard.

The Construction Of Two Light Sources With Adequate Intensity For Magneto-Optical Rotatory Dispersion Experiments, Norman D. Love

Masters Theses

Chapter I

Introduction

The phenomenon known as the Faraday Effect was discovered by Michael Faraday in the year 1845.¹ He discovered that when an isotropic substance of high refractive index is placed in a strong magnetic field which is parallel to a beam of plane polarized light, the plane of polarization is rotated. The rotation is proportional to H, the strength of the magnetic field; and to 1, the length of the light path in the sample. If X represents the rotation in minutes then

X = VH1.

The proportionality constant V is known as Verdet's constant. The units …

Investigation Of The Platinum-Rich Portion Of The Platinum-Tantalum Phase Diagram, Bob Dean Browning

Theses and Dissertations

The Pt-Ta binary system was investigated at two isotherms;1000°C and 1500°C, and at eleven alloy compositions in the range of 50 to 100 atomic percent platinum. The alloys were examined by x-ray diffraction and metallography. Three intermetallic compounds, Pt₂Ta, Pt₃Ta, and Pt₄Ta were found to exist in this composition range. The Pt₄Ta intermetallic appeared only at the 1500°C isotherm. Platinum dissolved tantalum substitutionally to 90 atomic percent at 1500 °C and to approximately 80 atomic percent at 1000 °C.

An Experimental Determination Of The Distribution Of Core Location Of Extensive Air Showers, Jerre P. Moore

Physics & Astronomy ETDs

It is the purpose of this paper to investigate the distribution of the core location of extensive air showers striking near an array of liquid scintillators.

Note Concerning Cloud Chamber Experiments With Positrons, H. M. Schwartz

Journal of the Arkansas Academy of Science

No abstract provided.

Scholasticism An Intellectual Basis And Unifying Principle Of Modern Science, Alice V. Johnson

Electronic Thesis and Dissertation

Amid the almost uninterrupted disintegration of systems during the last three centuries, the philosophy of St. Thomas has alone been able to stand the shock of criticism; it alone has proved sufficiently solid and comprehensive to serve as an intellectual basis and unifying principle for all the new facts and phenomena brought to light by modern science.

An Experimental Study Of The Cathode Fall In Helium And Argon With Wire Cathodes, L. G. Raub

Papers from the University Studies series (University of Nebraska)

It was recognized rather early in the study of the phenomena of discharge of electricity through gases that the ordinary laws of conduction as found in solid and liquid conductors are not applicable to gases. It was shown by Zeleny and independently by Child that Ohm's law by no means represents the distribution of potential between electrodes in an ionized gas, but that the potential gradient is large in the vicinity of the electrodes, and not uniform throughout the space between them. When the pressure of the gas surrounding the electrodes is reduced to one or two millimeters and a …