Astrophysics and Astronomy Commons^™

The Diffraction Of Polarized Light By A Conducting Straight Edge In The Geometrical Shadow, Richard W. Morris

Physics & Astronomy ETDs

Theory predicts that the diffraction pattern of a conduction straight edge will show deviations from the diffraction pattern of a non-conductor, and further, that these deviations will depend upon the polarization of the incident light. In this experiment the diffraction of polarized, coherent light from a monochromatic source by a metallic straight edge was studied in a region near the edge of the geometrical shadow. Two orientations of the polarization were used: one with the E vector of the polarized light parallel to the diffracting edge, and the other with the E vector perpendicular to the diffracting edge. Three different …

Determination Of The Orientation Of Air-Borne Instrumentation, David G. Miller

Physics & Astronomy ETDs

Air-borne devices have been used as a means of observation and collection of information in meteorology and atmospheric physics for many years. Only in recent years, however, has the increasing use of such devices been made for astronomical observations. A balloon-borne telescope at 80,000 to 100,000 feet, for example, has many advantages: the distortion, absorption and scattering of light by the atmosphere and the dependence on weather conditions, which plagues earthbound observations, are essentially eliminated. It seems apparent that astronomical observation will eventually be able to be made only by air­borne or satellite observatories. The decline in usefulness of the …

Single Crystals Of "Globular Molecules" From The Melt, Charles A. Aeby

Physics & Astronomy ETDs

This thesis is an investigation of the possibility of growing single crystals of dl-camphene, d-camphor, and cyclohexanol. These are organic compounds, characterized by "globular molecules", which form plastic crystals immediately below their melting point. Single crystals were desired in order to study, by ultra-sound techniques, properties pertinent to the evaluation of the elastic constants of these crystals. Primary emphasis was placed on growing crystals of dl-camphene, since it is conveniently handled at room temperatures.

Methods of growth from the melt were chosen because of the relatively fast growth rates, compared to vapor or solution techniques. Secondary considerations were simplicity of …

Phase Changes In Solid Cyclohexanol, William T. Griffith

Physics & Astronomy ETDs

Cyclohexanol is one of a group of organic compounds which exist in a “plastic crystal" solid phase, which is intermediate in its properties between the liquid phase and the solid phases stable at lower temperatures. It has been well established that the odd properties of the plastic crystal phase are due to the relatively unhindered rotation of the molecules about their lattice positions. At temperatures often considerably below the freezing point, these compounds undergo a solid-solid phase transformation in which this rotational freedom is lost. The heats and entropies of transformation at this lower transition point are generally larger than …

Large Angle Scattering Of Polarized Light By A Straight Edge, Theodore S. Fahlen

Physics & Astronomy ETDs

The purpose of this experiment was to observe the light diffracted into the geometrical shadow of a sharp and a blunt metallic straight edge using a polarized, very intense, highly coherent light source. The light source used was a ruby laser, and a Nicol prism was used to linearly polarize the laser light. Two polarizations of the laser beam were used: One with the E vector of the incident beam oriented parallel to the edge of the straight edge, and the other with the E vector oriented perpendicular to the edge. One photomultiplier tube was used to monitor the pulsed …

Variations In The Dielectric Constants Of Camphor And Camphene Under Pressure, Donald R. Wheeler

Physics & Astronomy ETDs

Camphor and camphene are two of a group of substances known as plastic solids. The plastic solids are all characterized by the ease with which they can be deformed. It has been suggested that this property is a result of a great number of mobile vacancies in the crystal lattice. Nabarro and Herring explain the "creep", characteristic of metals, in this way.

The Nuclear-Active Component Of Extensive Air Showers, E. Royce Fletcher

Physics & Astronomy ETDs

In 1900 Wilson (1900; 1901a; 1901b) in England and Elster and Geitel (1900) in Germany began a series of experiments which were ultimately to lead to the discovery of cosmic rays. Using an electroscope mounted in a grounded metal box, they were able to show that the air in a closed vessel has a slight residual conductivity. After careful experiments had eliminated insulator leakage and charged dust particles as possible sources of the observed current, Wilson speculated that the ionization might be due to the presence of some very penetrating radiation coming from outside the atmosphere. Unfortunately, however, he abandoned …

The Effect Of Cesium Vapor On The Emission Characteristics Of Uranium Carbide At Elevated Pressures, Philip W. Kidd

Physics & Astronomy ETDs

The saturated emission current from uranium carbide in the presence of cesium vapor were measured for four different bath temperatures: 167˚C, 197˚C, 227˚C, and 250˚C (the cesium arrival rates μ_a, in atoms/cm², were 3x10¹⁸, 1x10¹⁹, 3x10¹⁹ and 6x10¹⁹). The measurements were made with a “plasma anode” type tube immersed in a constant temperature oil bath. The design of the tube is shown, and the electronic circuitry is given with an explanation of the method of measurement. The experimental data for “electron emission vs 1000/T” was plotted for the experimental …

Neuron-Proton Scattering At 23.6 Mev, Jerome G. Beery

Physics & Astronomy ETDs

The angular distribution for neutron-proton scattering was measured at a neutron energy of m3.6 MeV. The measurement was made using the Los Alamos Variable Energy Cyclotron and a liquid hydrogen bubble chamber. The angular distribution was normalized to a total n-p cross section of 408 mb.

Application Of Shower Theory To High Energy Total Absorption Čerenkov Radiation Counter, Frederick Young

Physics & Astronomy ETDs

Theoretical calculations describing the performance of a Čerenkov counter designed as a total absorption gamma ray spectrometer for the energy range 100-1000 Msv are presented, using approximation "A" from the standard shower theory, and R. Wilson's quasi-analytical method of cascade shower analysis.

The Diffraction Of Polarized Light From A Laser By A Straight Edge, Robert Lawrence Berger

Physics & Astronomy ETDs

The purpose of this experiment was to determine the effect of the polarized light from a highly coherent light source on the diffraction pattern of a metallic straight edge.

Study Of Fission Neutron Spectra With High-Energy Activation Detectors, James A. Grundl

Physics & Astronomy ETDs

The energy spectra of neutrons from the fission of U235, U233, and Pu239 have been studied with seven high-energy activation detectors covering the range 0.6 to 16 Mev. Interpretation is in terms of the Maxwellian spectral function E^1/2 exp(-E/T). By means of a unique cavity arrangement within a moderator to obtain pure thermal-neutron-induced fission neutrons, the average energies of the three spectra are found to be in the ratios

U235: U233: Pu239= (1): (1.016+or-0.003): (1.039+or-0.003).

Differences between the normalized spectra are most pronounced at high energies as exemplified by the relative Pu239:U235 flux ratios 1.17+or-0.013 for 611 Mev.

Review Of The Physical Aspects Of Osmotic Pressure, Joseph F. Goffaux

Physics & Astronomy ETDs

It should be mentioned that this paper deals mostly with the work done by others and only a certain portion is original. The student wishes to state that he is presenting a thesis that would be considered theoretical and not empirical. The history of the work done in the field of osmotic pressure is treated at length and much of the theory used by the experimenters is derived. Many periodicals carry the papers written by the scientists of osmotic pressure and some of these men have spent perhaps fifteen of twenty years on their experiments.

A Transister Quenching Circuit For Geiger Counter Tubes, Andrew M. Simko

Physics & Astronomy ETDs

This thesis attempt to provide a solution to a basic problem inherent in the operation of Geiger-Mueller counting tubes, that is, reduction of the insensitive time, or “dead time”, following the discharge. Many researchers, using various quenching gases for internal quenching and various vacuum tube circuits for external quenching, have succeeded in reducing the “dead time” significantly. Reduction of the insensitive time provides more efficient and accurate counting. The solutions presented in this thesis utilize transistor circuits instead of vacuum tube circuits for external quenching. In an extensive research of current literature, no attempts to transistorize a quenching circuit could …

A Correlation Between The Responses Of A Cherenkov Counter, And A Liquid Scintillator, To An Extensive Air Shower, John Wolcott

Physics & Astronomy ETDs

To date there have been no adequate measurements of the energy spectrum of high energy cosmic gamma-rays. This information can only be obtained from instrumentation located above the atmosphere. An experiment has been designed by Dr. Leavitt at the University of New Mexico to obtain this information. It is to be orbited in the S-17 Orbiting Solar Observatory.

Fast Neutron Induced Fission Of U238, Michael J. Bennett

Physics & Astronomy ETDs

This work describes an experimental study of the energetics of the fission of U²³⁸ performed with solid state detectors. The fissions were produced by fission-spectrum neutrons from a reactor. The procedure used for calibrating the detector response is described and the effects of some experimental uncertainties, such as pulse height defect and neutron emission, are discussed.

A Theoretical And "Experimental" Investigation Of One-Dimensional Molecular Distribution Functions, Samuel Blackman

Physics & Astronomy ETDs

The presence of long range forces and of various types of boundary conditions may be expected to cause deviations from the well known Maxwell-Boltzmann velocity distribution, resulting in a spatially dependent velocity distribution. One possible method for obtaining a theoretical spatially dependent velocity distribution is to attempt an approximate solution for Liouville's equation. This is done in this thesis. The effects of a long range repulsive force inversely proportional to the interparticle separation as well as the effects of three types of wall boundary conditions upon the velocity distributions of a one-dimensional set of ordered particles have also been investigated …

A Radio Frequency Power Oscillator And Impedance Matching Device., Charles D. Preston

Physics & Astronomy ETDs

Certain molecules, called “globular” molecules, when first solidified form what are called “plastic” crystals. They are called “globular” either because they may exhibit an approximate spherical symmetry about their center of structure or because they may be small enough or of such a shape as to appear spherically symmetric because of rotation. The first case might be exemplified by methane (CH4) which has the configuration of a regular tetrahedron. The second case might be exemplified by hydrogen chloride (HCL).

A Proposed Modification Of The Available Momentum Region In Thomas-Fermi Theory, John F. Barnes

Physics & Astronomy ETDs

The statistical model of the atom, first propounded by Fermi and Thomas has proved a most useful approximation to the self-consistent field method in calculating electron distributions and fields in atoms. Because of its relative simplicity, it has found wide application as a means of predicting properties of free atoms and of solids. The original theory has been the subject of many modifications and refinements, some of which are reviewed in this paper.

The Leakage Neutron Spectrum Of A Spherical Critical Assembly Of U233, Larry E. Bobisud

Physics & Astronomy ETDs

In this paper the spectrum of the neutrons escaping from a critical sphere of U²³³ is investigated experimentally and theoretically. The experimental investigation involved exposing a nuclear emulsion to the neutron flux and, after development, examining the details of the proton-recoil tracks visible in the emulsion.

On The Velocity Of Sound In Cubic Crystals, Stuart Fleming Hayes

Physics & Astronomy ETDs

The object of this inquiry is to examine the relation between plane wave sound velocities in cubic crystals and the elastic constants of such crystals. Leading directly into this an extensive treatment of the classical theory of elasticity as it pertains to the cubic system. An application of the results will be made by detailing a means for obtaining the elastic constants of plastic single-crystals from measurements of velocity made on poly crystalline specimens.

The Time Required For Nuclear Fission, William Earn Stein

Physics & Astronomy ETDs

The present work is concerned with the mean lifetime of compound nuclei formed in the fast-neutron-induced-fission process. A new method for the measurement of these lifetimes is proposed. The present method is based on the recoil of the compound nucleus following neutron capture and the secondary electrons emitted by fission fragments. Previous experimental and theoretical work concerning the secondary electron yields for fission fragments and other charged particles are reviewed. The importance of the higher energy electrons, the so-called delta rays, formed in the primary ionization process is considered. The subsequent secondary ionization produced by these delta rays provirles a …

The He3 + T Reactions., Darryl B. Smith

Physics & Astronomy ETDs

The energy distribution of the alpha particles and of protons frim the He3+ t reactions have been measured for 1.9-Mev incident tritons at laboratory angles of 30° for alpha, and both 30° and 90° for protons. Absolute cross selections are obtained. The spectra are discussed in terms of a model which assumes that uncorrelated three-body breakup and several two-stage processes all contribute independently to the cross section. The calculations based on this model are in excellent agreement with the observed spectral shapes. The neutron-proton correlation corresponding to the unbound singlet state of the deuteron is observed. The binding energy of …

The Energy Spectrum Of Gamma Rays Produced In Interstellar Matter By The Primary Cosmic Rays, Duquesne A. Wolf

Physics & Astronomy ETDs

With the advent of the launching of space exploration in the last decade there has been parallel scientific effort to determine the nature of cosmic radiation found in space.

This theoretical study has the objective of determining the energy spectrum of gamma rays produced in interstellar matter by the primary cosmic rays.

Multiple Scattering Of High Energy Electrons In A Cerenkov Counter, John Rehnberg

Physics & Astronomy ETDs

The purpose of this thesis is to present a procedure for calculating the fraction of high energy electrons incident on a Cerenkov counter which are scattered out of the region of detection.

With the assistance of Professor Christopher P. Leavitt of the University of New Mexico, a method of solving the above problem has been established. The method uses the theory of multiple scattering as described by Rossi and Greisen and a numerical integration technique to evaluate the effective or average scattering distribution function for the Cerenkov counter. A relationship is developed which can be programmed on a Bendix G-15 …

Calibration Of A Liquid Scintillator With Geiger-Mueller Counters, William F. Hartman

Physics & Astronomy ETDs

It was the purpose of this experiment to examine the difference in the density determinations and, since the Geiger tube threshold is much lower, to calibrate the liquid scintillator so that it is capable to determining the absolute particle density with greater accuracy.

Diffraction Of Spherical Scalar And Vector Waves At Axial Points Of A Circular Aperture And Disk, Keith Leon Mcdonald

Faculty Publications

The following work treats Kottler's saltus problem of diffraction of electromagnetic waves emitted by a Hertzian oscillator source and the analogous Kirchhoff's scalar problem of waves emitted by a point source. The medium is a homogeneous isotropic dielectric. In the vector case a new exact solution of the basic integrals is presented, at axial points only, (a) behind a circular aperture in a "black'' screen, and (b) behind its complementary "black'' disk. The relative time-averaged intensity of energy flow is plotted for the disk only. It is shown that the scalar theory predicts considerably larger values than the electromagnetic theory …

A Telemetric Compass, Paul Nelson Jr.

Physics & Astronomy ETDs

In certain types of experiments involving balloon-borne equipment it is desirable to know how the orientation of the apparatus varies with time. The author has investigated a method of telemetering azimuthal orientation from a balloon to the ground, and has constructed a protoype of a telemetering magnetic compass. The basis of the compass is a rotating-ring magnetometer of the type first described by Nielsen (1) and used by others (2,3,4) for various purposes. The output of this device consists of two a.c. signals, whose relative phase is determined by the orientation of the magnetometer with respect to the external magnetic …

Anisotropy Of The Cosmic-Ray Flux Caused By An Interplanetary Magnetic Field, Ronald R. Harrington

Physics & Astronomy ETDs

The purpose of this study is to investigate the possibility that this diurnal variation in cosmic-ray flux may be due to a general dipole-like magnetic field centered upon the sun.

A Study Of The Elastic Scattering Of 25-Mev He3 Ions From Various Nuclei, Dale D. Armstrong

Physics & Astronomy ETDs

The validity of the assumption of strong absorption as the basis for the description of the interaction of He³ ions and nuclei was not definitely established and probably cannot be established without the application of more sophisticated theories.