Astrophysics and Astronomy Commons^™

On The Scintillation Of Stars., Mary Elizabeth Prince Phelan

Physics & Astronomy ETDs

The nature of stellar scintillation is important to the astronomer and to the atmospheric physicist, but little quantitative work has been done in this area. This paper describes the results of an objective study of stellar scintillation. The principle measurements were concerned with a determination of the scintillation pattern and rate of a star which was observed simultaneously in two photoelectric telescopes whose distance could be varied. Other items measured included variations in rate of scintillation with: stellar magnitude, stellar altitude, atmospheric changes, and time of evening.

Ultrasonic Suspension Of Liquid Droplets For Light Scattering Studies, David L. Cutchin

Physics & Astronomy ETDs

The construction and operation of an ultrasonic liquid droplet suspension device are described. The problem of generating intense sonic waves by matching the sonic transducer components is investigated. There is a description and analysis of a light scattering experiment performed on a suspended water droplet. The moat prominent characteristic of the scattered light was a rapid (10 to 100 cycles per second) time fluctuation in intensity. The variation in scattering cross section with droplet diameter predicted by the Mie theory and droplet shape oscillations are investigated as possible mechanisms producing the fluctuations.

Measuring Spin-Lattice Relaxation Times With A Super-Regenerative Spectrometer, Alfred C. Rester Jr.

Physics & Astronomy ETDs

Nuclear quadrupole resonance is a branch of radio frequency spectroscopy which was discovered in 1950 by Dehmelt and Kruger. (1). It is concerned with radio-frequency magnetic resonance absorption in molecular crystals. It results from the interaction of the nuclear quadrupole moment with the electric field gradient of the molecule charge cloud surrounding the nucleus. Different orientations of the nuclear axis relative to the field axis correspond to different energy levels. Resonance absorption takes place when an applied electromagnetic field cause transitions from one energy level to a higher one.

A Gated Digital Integrator And Its Application To The Measurement Of Nuclear Quadrupole Relaxation Times, Jack Curtis Wilcott

Physics & Astronomy ETDs

The thesis is divided into two sections. The first section discusses nuclear quadrupole resonance, relaxation times, experimental procedure, and apparatus, and some data is given. The second section describes the gated digital integrator in detail. The system uses the boxcar integrator technique for analyzing periodic waveforms obscured by noise. The average voltage of a small segment of the waveform is obtained by repeated sampling and is stored in a digital up-down counter. A digital-to-analog converter converts the stored digital number into a voltage to run a recording meter and to provide a feedback signal to compare with the input signal. …

Proton Measurements On A Rocket Probe Into The South Atlantic Radiation Anomaly, Russell G. Herron

Physics & Astronomy ETDs

1. Geomagnetically Trapped Radiation

A summary of results of space measurements during the 1950's has been published by Rossi (reference 1). Foremost among these results was the discovery of geomagnetically trapped radiation observed in increased counting rates in geiger counters on Sputnik II and Explorer I. In 1958, Van Allen (reference 2) correctly interpreted these experiments in terms of belts of geomagnetically trapped particles. In 1961, Singer and Lenchek (reference 3) reviewed progress in the burgeoning field of geomagnetically trapped radiation. In September 1962, Rosen et al. (reference 4) summarized the accepted information on the space radiation environment in a …

An Investigation Of Neutron Collimators And Their Application In Neutron Radiography., Roger A. Morris

Physics & Astronomy ETDs

One of the most important diagnostic tools in the fields of medicine and industry is the use of penetrating radiation to detect flaws, inhomogeneities, and abnormal conditions within an object without permanently changing or destroying the object being inspected. The equipment, technique, and type of radiation employed vary widely between hospital, shop, or laboratory depending upon the particular conditions that are encountered and the results that are expected. Probably the most widely used radiation types are X-rays or gamma-rays and their applications in the above-mentioned fields need no further description. However, beams of thermal neutrons are becoming more and more …

The (He3,D) Reaction On The N=28 Nuclei., Dale D. Armstrong

Physics & Astronomy ETDs

A beam of 22-MeV He3 ions from the Los Alamos variable energy cyclotron was used to investigate the (He3,d) reaction on Ca48, v51, Cr52, and Fe54. A solid-state E-deltaE mass-identification detector system was used. The use of a summing preamplifier for perfoming the coherent addition of the E and 6E pulses allowed the energy resolution to be reduced to the inherent energy spread of the cyclotron beam, which is 100 to 120 keV. Levels or groups of levels were resolvable up to an excitation of 5 to 6 MeV for all the nuclei that were studied, and angular distributions were …

The Atmospheric Neutron Spectrum At High Altitudes, Michael Sydor

Physics & Astronomy ETDs

A measurement of neutron flux in the range 30 -130 Mev at altitudes of 10, 670 feet and 100,000 feet was performed with a directionally sensitive proton recoil detector. The detector consisted of two counters of scintillator plastic which measured dE/dx and energy of proton recoils originating in a third plastic scintillator. Charged particles were eliminated by a guard counter. Energy calibration was performed with charged cosmic ray particles; efficiency and angular sensitivity were calculated. The angular response was checked at 10,670 feet, where a reasonable angular distribution of cosmic ray neutrons could be assumed.

Four balloon flights to 100,000 …

Stabilization Of A Balloon-Borne Package, Gary W. Tomlinson

Physics & Astronomy ETDs

It is desirable in certain applications of balloon-borne systems to stabilize the apparatus against rotation about the vertical axis and against tilting. The method of stabilization which will be discussed in this paper involves the use of a set of three gyroscopes which provide a reaction to any torques which would tend to rotate or tilt the package. A model was constructed which demonstrates the feasibility of this method. If the system is to be used for some type of astronomical measurement it may also be desirable to scan a portion of the sky at a constant rate. A method …

Force-On-The-Wall Calculations For One-Dimensional Dense Gases With Intermolecular Potentials., Thomas Daniel Butler

Physics & Astronomy ETDs

The theoretical study of dense gases with strong intermolecular forces is impeded by lack of sufficient experimental which to compare predictions of the properties. High speed computers can supply this information by calculating the detailed dynamics of molecular assemblages, thereby taking the place of an actual physical experiment. This information supplied by the computers not only can test the validity of existing theories, but also it can indicate directions for possible im­provement in the theoretical approximations.

In order to show the adaptability of computers to this task, this thesis deals with the theoretical and computer-experimental study of the force exerted …

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.