Physical Sciences and Mathematics Commons^™

Impurity-Concentration Profile For An Exponentially Decaying Diffusion Coefficient In Irradiation Enhanced Diffusion, J Kowall, David Peak, J W. Corbett

All Physics Faculty Publications

The diffusion equation is solved for a semi-infinite region in the case of irradiation-enhanced diffusion produced by a diffusion coefficient falling off exponentially in the medium. Near the surface the concentration profile due to enhanced diffusion has a larger concentration than the profile due to thermal diffusion; conversely far from the surface the enhanced-diffusion profile has a lower concentration than that due to thermal diffusion. Thus, this type of enhanced diffusion results in a more abruptly changing profile than does thermal diffusion.

Ionization Enhanced Diffusion, David Peak, J W. Corbett, J Bourgoin

All Physics Faculty Publications

The general three‐dimensional diffusion equations, along with the corresponding tensor diffusivities, are established for the normal ionization‐enhanced diffusion mechanism (which is equivalent to a general two‐channel diffusion mechanism) and for the Bourgoin mechanism, the latter being explicitly developed for the diamond lattice.

The Effect Of The Gradient-Drift Term On Type I Electrojet Irregularities, D. T. Farley, Bela G. Fejer

Bela G. Fejer

We hypothesize that type 1 VHF radar echoes can only be observed when the electrojet plasma is linearly unstable at half the radar wavelength and that further, for reasons not yet understood, the phase velocity of the unstable waves always corresponds to the threshold conditions for instability, even when the destabilizing forces (electron drift and plasma density gradient) exceed the threshold. This phase velocity, which produces the Doppler shift of the radar echoes, is usually close to the ion acoustic velocity of the medium but can differ from it to some extent because of the effect of the density gradient. …

Vertical Structure Of The Vhf Backscattering Region In The Equatorial Electrojet And The Gradient Drift Instability, Bela G. Fejer, D. T. Farley, B. B. Balsley, R. F. Woodman

Bela G. Fejer

Radar measurements made with high spatial resolution and large dynamic range at the Jicamarca Radar Observatory near the time of reversal of the electrojet current provide further proof that the gradient drift instability is in fact responsible for the type 2 irregularities. Echoes are received over a much wider range of altitudes at night than during the day partly because of the change in character of the background electron density profile and partly because of recombination effects, which can be important during the day. It is also shown that one must be cautious, particularly at night, in associating the mean …

Oblique Vhf Spectral Studies Ofthe Equatorial Electrojet, Bela G. Fejer, D. T. Farley, B. B. Balsley, R. F. Woodman

Bela G. Fejer

A new narrow-beam antenna at the Jicamarca Observatory permits oblique (zenith angle, 25°) radar spectral studies of the electrojet with an altitude resolution down to 1.1 km. Only daytime observations are possible presently, however. The general altitude variations in spectral shape observed are consistent with linear instability theory, if the effect of recombination is included. The height at which the mean Doppler shift of the echo maximizes, however, is about 4 km higher than one would expect on the basis of electrojet models. An increase in the assumed collision frequency would remove the discrepancy. Other data presented strongly suggest that …

Inclusion Of Rectangular And Triangular Geometries In The Space-Dependent Kinetics Code, Fx2, Ted Perry

Undergraduate Honors Capstone Projects

The computer code FX2 is used to model liquid-metal fast-breeder reactors now being developed by the U. S. Atomic Energy Commission. These reactors differ from thermal reactors in that they have no moderator material in their cores and thus operate at mean neutron energies of 100 keV or more as opposed to neutron energies of less than 1 keV for thermal reactors. Also these reactors have the advantage that as a consequence of the high neutron energies, these reactors can be used to "breed" their own fuel: enriched ²³⁸U placed in the core is changed into plutonium which can …

Auroral Energy Input From Energetic Electrons And Joule Heating At Chatanika, Vincent B. Wickwar, M J. Baron, R D. Sears

All Physics Faculty Publications

With the incoherent scatter radar at Chatanika, Alaska, a wide variety of measurements can be made related to the ionosphere, magnetosphere, and neutral atmosphere. A significant parameter is the amount of energy transferred from the magnetosphere into the ionosphere and neutral atmosphere during periods of auroral activity. In this report we examine a procedure whereby the incident energy flux of auroral electrons is ascertained from radar measurements. As part of the process we compare radar-determined fluxes with those ascertained from simultaneous photometric observations at 4278 Å. The fluxes obtained by both techniques had similar magnitudes and time variations. If we …

A Theoretical Proton-Proton Pair Production Cross-Section Calculation, Jay W. Phippen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The calculation of both electron-pair and muon-pair production cross-sections was made using Feynman's quantum electrodynamics. Pseudo-scaler coupling was used between the nucleons and vector coupling was used between the photon and the Fermions. The protons were considered as Dirac particles and radiative corrections were omitted.

Eight fourth-order Feynman-Dyson diagrams were used. The subsequent sixty-four TRACES were reduced to seven basic topologically different TRACES. From the seven basic TRACES, it was possible to generate the sixty-four TRACES by the proper permutations of the variables.

With the mathematics and the corresponding computer programs written down, data (energies and momenta which represent the …

Incoherent Scatter Radar Observations Of Westward Electric Fields And Plasma Densities In The Auroral Ionosphere, 1, M P. Banks, C L. Rino, Vincent B. Wickwar

All Physics Faculty Publications

This paper reports the results of incoherent scatter radar observations of high-altitude ion drifts and other plasma parameters made February 24, 1972, at Chatanika, Alaska (L = 5.7), during a period of magnetic disturbance. For this experiment, conducted between 0909 to 1303 UT (2309 to 0303 AST), the radar line of sight was held fixed in the magnetic meridian plane so that the observed north-south ion drifts could be interpreted in terms of a westward electric field that ranged in magnitude from −10 to +35 mV m⁻¹. The results confirm many effects found previously through other experimental …

Unity In The Theory Of Elementary Particles Through Group Theory, Douglas Karl Lemon

Undergraduate Honors Capstone Projects

Science is the process of seeking unity in the diversity of natural phenomenon. The purpose of this paper is to demonstrate that group theory brings unity to the theory of elementary particles. The prime motivations are first, to find a quantitative representation of the Lorentz transformation, and second, to find a quantitative representation of angular momentum. Since both of these have continuous parameters, groups with continuous parameters, particularly Lie groups, are of interest.

The first portion of the paper develops the definition of Lie groups and their associated Lie algebras. The prerequisite definitions of transformations, groups, group representations, and continuous …

The Thermolysis Of Bornyl And Iso-Bornyl Acetates, Allen Reed Jensen

Undergraduate Honors Capstone Projects

Recent investigations in the area of acetate gas phase thermolysis indicate a mechanism which involves a similar transition state despite the acetate used. The reaction preferentially goes through a cis-elimination with the β-hydrogen atoms, proceeding through a six-membered ring transition state.

The purpose of this study is to examine the effect of a strained bicyclic ring system upon the mechanism of acetate thermolysis. Throuqh kinetic studies and product identification of the pyrolyzed products of bornyl and iso-bornyl acetate, an insight into the preferred mechanism can be obtained. A previous study (cited later) indicated that the accepted six-membered cis …

Combined Airglow And Incoherent Scatter Observations As A Technique For Studying Neutral Atmospheric Variations, L L. Cogger, Vincent B. Wickwar, Herbert C. Carlson

All Physics Faculty Publications

Night airglow 6300 Å intensities and electron density altitude profiles observed at Arecibo have been combined with dissociative recombination theory to obtain information about the nighttime variation of F-region N₂ and O₂ densities. The application of this technique is illustrated using data from two nights in March 1971. The gross nighttime variation shows reasonable similarity to the Jacchia [1970] model, and also follows the time variation of the measured exospheric temperature. However, on both nights there is evidence of a postmidnight enhancement of the O₂/N₂ density ratio associated with a rapid decrease in the …

Incoherent-Scatter Radar Observations Of Westward Electric Fields, 2, C L. Rino, Vincent B. Wickwar, P M. Banks, E Rieger, S Akasofu

All Physics Faculty Publications

In this paper we describe the results of a series of geomagnetic meridian plane radar incoherent scatter plasma transport measurements. From such data the eastward (zonal) component of the electric field can be deduced. The results show that the electric field has an eastward component whenever the discrete auroras are northward of the region of the measurement. The zonal field component turns westward as the discrete auroras move equatorward of the region of the measurement. Thus there is an eastward electric field boundary near the equatorward limit of the discrete aurora, which is the poleward boundary of the diffuse aurora …

A Relativistic One Pion Exchange Model Of Proton-Neutron Electron-Positron Pair Production, William A. Peterson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Proton-neutron electron-positron pair production cross sections are calculated in the framework of the pseudoscalar one-pion exchange model in a fully relativistic manner.

A computer program has been developed to evaluate invariants and Dirac traces for a given data point.

The sections for symmetric coplanar events for laboratory kinetic energies of 10 to 250 MeV were calculated for pair angles of 20° to 120°.

Frequency distributions were also calculated, at a laboratory energy of 200 MeV, using a random number generator to select data points. The frequency distributions are illustrated by curves.

It was noted that the inclusion of heavier bosons …

Ionization‐Enhanced Diffusion: Ion Implantation In Semiconductors, J Bourgoin, David Peak, J W. Corbett

All Physics Faculty Publications

A model for the diffusion of implanted interstitials during implantation is introduced and shown to be able to account for the tails observed in ion profiles. It is argued that mechanisms of ionization‐enhanced diffusion can explain some of the anomalous diffusion mechanisms observed in semiconductors. Indications for the existence of such mechanisms in the field of ion implantation in semiconductors are discussed.

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

All Physics Faculty Publications

Linear-combination-of-atomic-orbitals-molecular-orbitals cluster calculations using the extended Hückel theory are carried out for the interstitial carbon in the diamond lattice. The results suggest that the interstitial configuration is not the tetrahedral or hexagonal site, as has been previously assumed, but is instead an "interstitialcy" configuration, i.e., either a split- 〈100〉 interstitial (which our results favor) or a bond-centered interstitial. The predicted minimum-energy configuration changes with charge state, suggesting that the interstitial in the diamond lattice is a possible example of the Bourgoin mechanism of athermal migration of a defect in the presence of ionizing radiation.

The Momentum Of The Photon, K F. Ratcliff, David Peak

All Physics Faculty Publications

No abstract provided.

Diffusion-Controlled Reaction Kinetics, David Peak, J W. Corbett

All Physics Faculty Publications

The theory of diffusion-controlled correlated reaction kinetics is developed for the radiation boundary condition (RBC) at the reaction surface. Limited only by the assumptions of purely radial spatial dependence, of a spherical reaction surface, and of continuum diffusion, these results comprise a complete solution for these kinetics. The limiting solutions are obtained for the case of the Smoluchowski boundary condition (SBC) at the reaction surface; numerical solutions are presented, as are the analytic forms of certain limiting cases. The initial recovery for the RBC is linear in time, whereas for the SBC it is well known to be proportional to …

The 6300Å Predawn Enhancement: Excitation By Protoelectrons From The Magnetic Conjugate Point, Vincent B. Wickwar

All Physics Faculty Publications

Incoherent scatter and tilting filter photometer data from Arecibo Observatory were combined to search for a contribution to the 6300 Å predawn enhancement due to impact excitation by photoelectrons from the magnetic conjugate point. Prior to about 105° conjugate solar zenith angle, calculations of the 6300 Å intensities due to dissociative recombination gave good agreement with the observed intensities. Then, with the arrival of conjugate photoelectrons (confirmed by plasma line enhancements), the observed intensities rose above the calculated, the difference increasing until a plateau was achieved at a conjugate solar zenith angle of about 95°. The difference or residual intensity …

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.

Interpretation Of A Unified Theory Of Gravitation And Symmetry Breaking, David Peak, A Inomata

All Physics Faculty Publications

The formalism of Moen and Moffat is interpreted as a Yang-Mills theory set in a space-time generally endowed with curvature and torsion.

Summation Over Feynman Histories In Polar Coordinates, David Peak, A Inomata

All Physics Faculty Publications

Use of polar coordinates is examined in performing summation over all Feynman histories. Several relationships for the Lagrangian path integral and the Hamiltonian path integral are derived in the central‐force problem. Applications are made for a harmonic oscillator, a charged particle in a uniform magnetic field, a particle in an inverse‐square potential, and a rigid rotator. Transformations from Cartesian to polar coordinates in path integrals are rather different from those in ordinary calculus and this complicates evaluation of path integrals in polars. However, it is observed that for systems of central symmetry use of polars is often advantageous over Cartesians.

The Alignment Procedure Of A Two Crystal Spectrometer, Jay W. Phippen

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

For the sake of completeness, it was felt that a brief resume' of x-ray scattering theory as it affects the alignment procedure of a two crystal spectrometer would be beneficial.

X-ray diffraction from a single crystal slab.

W. L. Bragg (1912) tried the experiment of reflecting a beam of x-rays from the cleavage surface of a crystal and found on the photo-graphic plate a spot at the angle of reflection. He then replaced the photo graphic plate with an ionization chamber which he mounted so that it could be rotated about the axis upon which the reflecting crystal is …

Movement Of Atrazine In Soil Under Furrow Irrigation, Jyothi Veerabhadrappa

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Movement of atrazine in response to furrow irrigations was studied using the samples of Timpanogos silt loam soil. Distribution in soil profile of surface applied herbicide was determined by drawing samples of water extracts through porous cylinders. Atrazine quantity was determined by spectrophotometer.

It was observed that the herbicide found in the water extracts was an indication of the quantity present in the soil. The herbicide moved readily with the applied water. Irreversible thermodynamic model could not be applied because of the initial and final boundary conditions. The pattern of movement was in conformity with the chromatographic theory.

Simultaneous Movement Of Water And Herbicides In Unsaturated Soils, Ming-Shyong Yang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Since weed killers were developed in the early part of the decade beginning in 1940, herbicides have been increasing in use until they are now widely used to control weeds. The application of herbicides has thus become a regular agricultural and ecological practice.

Simultaneous Flow Of Heat And Water In Plant Tissue, Gaylon Sanford Campbell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Although biological phenomena may be partially described in a general way without the use of mathematics and physics, the experimental results may be more meaningful if they are analyzed on the basis of physical and mathematical laws. The complexity of biological systems has made the application to them of mathematics and physics rather difficult, and only recently has much progress been made. Although it has yet been possible to describe only a few simple biological systems by actual equations, a great deal of qualitative information may be obtained by applying physics and mathematics. Russell (1960, p. 439) said

In principle …

Relations Between Transpiration, Leaf Temperatures, And Some Environmental Factors, Ronald Kay Tew

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Transpiration is the loss of water in vapor form from a plant. This is essentially the same process as evaporation except that it is modified by plant structure. Large quantities of water are removed from the soil, transferred through the conducting tissues of the plant, and dissipated into the air each day. As soon as the water is lost to the atmosphere, it becomes unavailable for human use.

A Matrix Formulation Of The Least-Squares Method And Its Application To Nuclear Decay Schemes, Otto Harry Otteson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Many people call physics an ''exact science". This may be true depending on our definition of exact. Most dictionaries include as a definition of exact the words "strictly accurate". The average man thinks of an "exact science" as one which yields "strictly accurate'' results. Physics then is exact only to a degree.

The Influence Of Temperature On The Impedance To Water Flow Through Plants, Royal Duane Jensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This era has been termed the atomic or space age. The greatest concern of most people seems to be centered around survival from the destruction and suffering that might be caused by atomic and nuclear weapons. However, along with this, the world is confronted with perhaps a greater disaster--a potential calamity seldom realized by most people, yet a problem which grows more serious in the world each year--a tragedy which would probably be worse than destruction from nuclear weapons. This encroaching catastrophe is starvation.

Even today the majority of the people in the world do not have enough food. Each …

The Freezing Point Of Water In Puddled And Unpuddled Soils At Different Soil Moisture Tension Values, Robert B. Campbell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A technique that will adequately describe the physical condition of water in the soil has long been desired by scientists. The method should include the effect of soluble materials on the osmotic pressure of the soil solution, and also the effect of surface force action between the soil and soil water.

Parker (8) demonstrated that the freezing point was reduced in the presence of finely divided material. This suggested the possibility of using the cryoscopic procedure to measure the physical condition of water soil. More recently, the introduction of Thermistors for accurate temperature measurement have made it desirable to investigate …