Astrophysics and Astronomy Commons^™

Geophysical Institute Annual Report 1966-67, University Of Alaska Fairbanks. Geophysical Institute

GI Reports

The 1966–67 Geophysical Institute Annual Report presents an overview of the year’s scientific research achievements across the Institute’s disciplines, alongside operational summaries covering finances, administrative changes, and other key activities.

Equation Of State Of Sodium Chloride, Daniel L. Decker

Faculty Publications

Because of many requests, I wish to publish the following numerical table of results for the equation of state of NaCl as calculated in an earlier paper1 along with a few comments on various proposed equations for NaCl. Table I gives the pressure in kilobars at the corresponding values of t.a/ao and temperature in the appropriate row and column. The parameter t.a/ao is the fractional compression of the lattice parameter where the standard value ao is the appropriate lattice parameter at zero pressure and 25°C. The increments between the values given in the table were chosen such that one can …

Model Of Electron Correlation In Solids, Everett G. Larson, Walter R. Thorson

Faculty Publications

The usual Hartree-Fock model (energy-band theory) does not always give an adequate description of electronic structure in a solid, because it ignores the effects of electron correlation. It was shown first by Wigner that such a situation always develops in an electron ''gas'' at sufficiently low density; a solid structure described by ''resonance'' of Heitler-London pair bonds between electrons localized on neighboring atoms is then a good model of the system.The transition from a Bloch-type state to such a highly correlated state as a function of electron density (lattice parameter) is a problem of considerable interest for the theory of …

Surface-Wave Phenomena At A Water-Air Interface., Benjamin W. Woodward

Physics & Astronomy ETDs

The existence of a surface wave accompanying total internal reflection of light in a dielectric material was derived classically to satisfy boundary conditions at the surface. Using this fact, in 1929 J. Picht proposed a mechanism for total reflection that led to the conclusion that a finite ray of light would undergo a small translation at the boundary, parallel to the boundary and in the plane of incidence. In 1943 Goos and Hänchen made quantitative measurements of this translation or shift. Subsequently many theories have been advanced analyzing this phenomenon in detail, but as of this writing no other experimental …

Pressure Calibration To 100 Kbar Based On The Compression Of Nacl, R. N. Jeffrey, J. Dean Barnett, H. B. Vanfleet, H. Tracy Hall

Faculty Publications

An independent determination has been made of the transformation pressures assigned to the high-pressure transformations in Ba and Bi which are generally used for calibration points. The metals were imbedded in NaCl, and the transitions were detected by the resistance change of the metal while the NaCl lattice parameter was simultaneously measured by x-ray diffraction. The NaCl compression values determined at the fixed points were related to pressure by reference to the semiempirical compression curve of Decker. The Ba I-II and Bi III-V transformations at room temperature were assigned thermodynamic equilibrium values of 53.3 ±1.2 kbar and 73.8 ±1.3 kbar, …

Angular Distribution Of Neutrons In Atmosphere Produced By Protons, Donald Stuart

Physics & Astronomy ETDs

In connection with the balloon flown directional neutron detector experiments in progress, the following theoretical problem presented itself. Find the angular distribution of neutrons incident upon a detector. This is investigated under varying conditions using a computor program prepared for this problem. Two models for the problem are considered in this paper. In the first model we choose the simplest conditions that approximate a possible physical situation. This consisted of considering that the system was completely isotropic. For certain altitudes this gave very good results as can be seen by the curves. Then modifications to the theory are discussed. This …

Geometrical Representations Of Relativistic Motion, Jeffrey H. Robbins

Physics & Astronomy ETDs

This investigation begins with the development of a transformation or mapping in velocity space of such a character that velocities are mapped into a quantity that adds linearly, while velocities add non-linearly according to the Einstein Law of Addition, and has no upper limit to its magnitude, i.e., when the speed of an object approaches that of light in a vacuum, this quantity becomes infinitely large. Kinematic relationships, in Newtonian form, for a particle undergoing acceleration, are developed in a frame of reference that remains attached to the particle using the new variable (W). It is found that relativistic energy …

Coulomb Excitation Of The Ytterbium Isotopes., John M. Palms

Physics & Astronomy ETDs

Coulomb excitation studies have been performed on the ytterbium isotopes 171, 172, 173, 174, and 176 using oxygen ions having energies up to 55 MeV. Resulting de-excitation gamma rays have been observed in particle coincidence with a NaI(Tl) detector and as single spectra with a Ge(Li) detector. The ground state rotational bands of the Yb171 and Yb173 isotopes have been excited to the 13/2- level. The 13/2- and 11/2-levels of both nuclei have not been reported before. In addition to the transitions from the ground state band, gamma rays were observed from Yb171 and Yb173 coming from other bands. A …

Investigation Of Propagation Of Light Through Gases And Air Structures Treated As Wave Guides., Richard W. Christiansen

Physics & Astronomy ETDs

The equations defining the propagation of electromagnetic radiation down cylindrical dielectric wave guides are developed. A Helium-Neon laser is used to illuminate several different cylindrical wave guides. The propagation nodes are recorded on photographic plates. Using the field equations, the electric field on a transverse plane is plotted and used to explain some HE_im modes observed. The patterns recorded on the photographic plates are described and discussed in terms of the propagation modes.

Measurements Of Continuous X-Ray Spectra With A Scintillation Spectrometer, Ellery Strom

Physics & Astronomy ETDs

Scintillation spectrometer measurements were made of the x-ray spectra produced by a constant-potential x-ray unit operating at 100, 150, 200, 250, and 300 kV. An attempt was made to measure the absolute intensity as well as the spectral distribution. In order to reduce the counting rate to a measureable level, it was necessary to place the thallium-activated sodium-iodide detector 50 meters from the target. Since the air attenuation was quite large, measurements were made both in air and in helium. In order to contain the helium, an Orangeburg pipe was employed, and its effect on the spectra was determined by …

Some Factors Which Influence The Intensity And Resolution Of Beams In Neutron Diffractometers, Robert G. Wenzel

Physics & Astronomy ETDs

The problems of the intensity and resolution of a neutron diffractometer are considered, both for elastic and inelastic scattering studies. The considerations are applied to the choice of parameters for a new diffractometer. First to be taken up is the manner in which the intensity of a diffraction monochromating system varies with its collimators, which affects both kinds of studies. A model is chosen and used to derive an expression tor the intensity. The expression is checked experimentally and found not be be valid over the range of collimators available. However, over a smaller range, such as those collimators which …

High Frequency Scattering From A Schroedinger Square Well, Robert R. Thede

Physics & Astronomy ETDs

Many observations have been made of the enhanced back scattering of light waves from water droplets. This phenomenon, commonly referred to as the glory, is inexplicable in terms of ray optics. Calculations based upon the Mie series solution to the scattering of an electromagnetic plane wave from a dielectric sphere suggest that this pronounced scattering is due to surface waves which travel around the sphere and are emitted in phase preferentially in the forward and backward direction. These results have also been verified experimentally by examining the backscattered light from a water droplet.

X-Ray Diffraction Studies On Tin To 100 Kilobars, J. Dean Barnett, Vern E. Bean, H. Tracy Hall

Faculty Publications

The high-pressure equilibrium phase diagram of tin is investigated, and the crystal structure of Sn II at 98 kbar and 25degrees C is shown to be body-centered tetragonal with a=3.70 Angstroms, c=3.37 Angstroms, c/a=0.91, and with two atoms per unit cell. The linear compressibility of white tin is given at 25degrees C up to the high-pressure transformation at 92 kbar, and the latent heat of the transformation is measured as 225 cal/g-atom.

The Interaction Of 22-Mev He³ Particles With Fe⁵⁶, ⁵⁸ And Ni ⁵⁸, Edward R. Flynn

Physics & Astronomy ETDs

A systematic study is made of the interaction of 22-MeV He³ ions with several medium-weight nuclei. The central purpose of this study is to compare the interactions induced by this strongly absorbed, spin-­one-half projectile to those induced by the more commonly used nuclear probes: neutrons, protons, and alpha particles. The target nuclei are restricted to three cases, Fe^56,58 and Ni⁵⁸, but the scope of the experimental studies is as extensive as the variety of experimental equipment available would allow. These studies then include the elastic and inelastic scattering as well as the neutron spectra in the …

The Structure Of The Vibrational Relaxation Zone Of Shock Waves In Oxygen, Robert W. Lutz

Physics & Astronomy ETDs

The vibrational relaxation of pure oxygen has been studied in incident shock waves in the temperature range l000-3700° K. The re­laxation process was observed by measuring density gradients in the relaxation zone with the quantitative laser schlieren technique. The high sensitivity of this technique allowed determination of the relaxation time T, defined by the Bethe-Teller equation

= [ E - E ],

as a function of temperature and pressure in the relaxation zone. The variation in P the relaxation time at one atm, during th individual experiments, was found to agree with the over-all temperature dependence derived from the entire …

Charged Particle Fluxes In The South Atlantic Radiation Anomaly, Nicholas S. P. King

Physics & Astronomy ETDs

Data from a scintillator and two Cerenkov counters aboard the 0S0-B2 satellite are converted from counting rates to omnidirectional fluxes in the South Atlantic Radiation Anomaly. Isointensity contours are obtained for the anomaly with omnidirectional fluxes being of the order of 90 protons/cm2 -sec and 5 x 10 3 electrons/cm2 -sec. The South Atlantic Radiation Anomaly is postulated to include an electron dump into the earth's atmosphere due to the observed differences between the isointensity distributions for protons and electrons.

An Experimental Study Of The Back Scattering Of Coherent Light From Falling Water Drops., William Ogle

Physics & Astronomy ETDs

Introduction

The purpose of this study is to make a statistical investigation of the backscattering of light from freely falling water drops, and to determine if the surface wave is a significant contribution to the backscattered intensity from large drops.

An Experimental Study Of The Rate Of Evaporation Of Water Droplets., Pyung Syk Ro

Physics & Astronomy ETDs

The basic equation (Maxwell equation) for the evaporation rate of small droplets motionless relative to the ambient gas is verified by our experiment using an ultrasonic droplet suspension device. By using an ultrasonic device, a good approximation to the conditions of evaporation of free water droplets ranging from 0.4 mm to 2.0 mm in diameter is obtained.

Since it is expected that the back-scattering cross section of an incoherent light beam from a water drop is proportional to the square of the radius of the water drop, the possibility of measuring evaporation rates by using incoherent light is suggested. This …

A Theoretical Study Of Light Scattering From Water Droplets., Aaron J. Cox

Physics & Astronomy ETDs

No abstract provided.

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 …

Equation Of State Of Nacl And Its Use As A Pressure Gauge In High-Pressure Research, Daniel L. Decker

Faculty Publications

The pressure as a function of lattice parameter and temperature has been calculated for NaCl over a pressure range of 0 to 500 kbar for temperatures between 0degrees and 1500degrees C. The calculation used the Mie-Gruneisen equation of state with Born-Mayer type repulsion terms between first and second nearest neighbors. The Gruneisen constant was expanded about its value at room temperature and atmospheric pressure; the first coefficient in the expansion being evaluated by forcing the calculated thermal expansion at atmospheric pressure to fit the experimental results of Enck. The two empirical parameters in the repulsion terms were evaluated using the …

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 …