Digital Commons Network^™

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 …

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 …

Study Of Stopping Sites Of B12 Nuclei Implanted In Hexagonal Single-Crystals, Francis David Correll, Richard C. Haskell, Leon Madansky

All HMC Faculty Publications and Research

A series of experiments to study the stopping sites of 12B nuclei implanted in single crystals of Be and Mg will be discussed. Previous measurements of the quadrupole couplings of 12B in these metals indicated that two different stopping sites existed, one of which produced a negligible quadrupole coupling.

High-Temperature Annealing In Electron-Irradiated Cds, David C. Look

Physics Faculty Publications

The room‐temperature irradiation of as‐grown n‐type CdS by 1‐MeV electrons results in an increase in carrier concentration. The damage anneals in the temperature range 250–300°C, and a study of the annealing kinetics reveals an activation energy of about 1.3 eV which is attributed to sulfur‐vacancy motion.

Dispersion Curves For Surface Electromagnetic Waves With Damping, Ralph William Alexander, G. S. Kovener, Robert John Bell

Physics Faculty Research & Creative Works

The Recent Observation of Back bending in the Dispersion Curves of Surface Plasmons on Silver Can Be Explained by Use of Fresnel's Equations. in the Presence of Damping, the Results of Attenuated-Total-Reflection Measurements Can Be Displayed as Dispersion Curves Either with or Without Back bending. the Measurements for Silver with Back Bending Are Expected for Experiments in Which the Frequency is Fixed, and the Propagation Constant (Or Angle of Incidence) is Swept. © 1974 the American Physical Society.

Cryogenic Thin-Film Electron Emitters, Pavel Smejtek, David G. Onn, M. Silver

Physics Faculty Publications and Presentations

Thin‐film electron emitters are described, which operate below 200°K and below a limiting critical applied voltage (νc) in a stable temperature‐independent regime. Current‐voltage characteristics and normal electron energy distributions are presented. Fabrication and operation criteria are outlined. Comparison with temperature‐dependent emitters is made, and possible conduction mechanisms discussed briefly.

Charge Transfer Between O Ions And O2 Molecules In The Ground State And Singlet Delta Excited State, R. F. Mathis, William R. Snow

Physics Faculty Research & Creative Works

A crossed-beam apparatus has been used to study charge transfer between O- ions and O2 molecules in the ground state and in the metastable, singlet delta, excited state. The energy of the incident ions ranged from 10 to 10000 eV. The cross section for charge transfer between O - and ground state O2 was found to have a maximum of 7.8X10-16 cm2 at about 5 keV. At the lower energies there is good agreement with the previous measurements of Snow et al. and Rutherford and Turner who also used crossed beam techniques. The cross section for charge transfer between O- …

Structural Strain In Small Prenucleation Water Clusters, Donald E. Hagen

Physics Faculty Research & Creative Works

A method is developed for incorporating strain energy into a microphysical treatment of small prenucleation water clusters. The molecules are arranged in a clathrate-cage structure, and this structure is allowed to relax to minimize the strain energy resulting from hydrogen bond stretching and bending. The method is applied to various cluster sizes up to 130 molecules and the results are compared with the classical liquid drop model. The effect of anharmonic terms in the interaction is included.

Fresnel Drag In Uniformly Moving Media, William F. Parks, J. T. Dowell

Physics Faculty Research & Creative Works

A general first-order formula is derived for the Fresnel-drag effect in a uniformly moving medium with a plane surface. The two classical equations due to Lorentz and Laub are shown to be special cases corresponding to different experimental arrangements. The recent experiment of Bilger and Zavodny on Fresnel drag in a ring laser is discussed. © 1974 The American Physical Society.

Measurements Of The Average Electric Dipole Polarizabilities Of The Alkali Dimers, Robert W. Molof, Thomas M. Miller, Henry L. Schwartz, Benjamin Bederson, John T. Park

Physics Faculty Research & Creative Works

The average electric dipole polarizabilities of the homonuclear alkali dimers have been measured in an electric deflection experiment. The molecular results are normalized to the corresponding atomic polarizabilities by comparing deflections of atomic and molecular alkali beams passing through an inhomogenous electrostatic field. The average polarizabilities in units of 10-24 cm3 are: Li2(990°K), 34±3; Na2(736°K), 30±3; K2(569°K), 61±5; Rb2(534°K), 68±7; Cs2(515°K), 91±7. Copyright © 1974 American Institute of Physics.

On The Lambda Transition In Solid Orthohydrogen, Harry A. Brown

Physics Faculty Research & Creative Works

No abstract provided.

Optical Pumping In A Flowing Helium Afterglow With Additive Metal Impurity Atoms, Laird D. Schearer

Physics Faculty Research & Creative Works

It is demonstrated that in a Penning collision of optically oriented metastable helium atoms with an impurity metal atom such as barium, both the longitudinal and transverse components of spin angular momentum are conserved. This results in a polarization of the ion which may be detected by optical emission in the case of excited ion levels or absorption for the ground states. A series of experiments is described which demonstrates the spin dependence of the Penning-collision process. The magnetic resonance of excited-state ions may be observed directly; from the resonance-linewidth radiative lifetimes may be measured. © 1974 The American Physical …

Evaluation Of Model For The Contributin Of Phonon-Induced Tunneling To Donor Esr Spectral Narrowing In Germanium, David L. Meier, William F. Parks, Edward Boyd Hale

Physics Faculty Research & Creative Works

The model commonly assumed to explain the narrowing of the ESR spectra of donor impurities in germanium is examined in detail. This model combines the Anderson line-narrowing theory with the Miller and Abrahams theory for the phonon-induced tunneling (hopping) of an electron between impurities. The predictions of this model are found to be in drastic disagreement with experimental results now available. It is shown that the narrowed linewidth should depend strongly on donor concentration, acceptor concentration, and temperature. Future spin-resonance experiments in highly compensated samples may show the effects of hopping, but no evidence now exists which indicates that hopping …

Statistical Time-Dependent Model For The Interstellar Gas, H. Gerola, Menas Kafatos, R. Mccray

Mathematics, Physics, and Computer Science Faculty Articles and Research

We present models for temperature and ionization structure of low, uniform-density (n ~ 0.3 cm^-3) interstellar gas in a galactic disk which is exposed to soft X-rays from supernova outbursts occurring randomly in space and time. The structure was calculated by computing the time record of temperature and ionization at a given point by Monte Carlo simulation. The calculation yields probability distribution functions for ionized fraction x, temperature T, and their various observable moments. These time-dependent models predict a bimodal temperature distribution of the gas with structure in x, T that agrees with various observations. Cold regions in the low-density …

Comments On 'Fluctuations In Guiding Center Plasma In Two Dimensions', George Vahala, Linda L. Vahala, David Montgomery, Glenn Joyce

Electrical & Computer Engineering Faculty Publications

It is stated that the principal result of the paper by Taylor and Thompson (see abstr. A14511 of 1973) on autocorrelations in density for the electrostatic guiding center plasma in two dimensions is wrong owing to an incorrect integration. It is further stated that there is no meaningful distinction between an `interaction cutoff' and a `fluctuation cutoff'.

Phase Transitions In Antiferromagnets In External Magnetic Fields: Mossbauer Spectroscopy, Richard B. Frankel

Physics

No abstract provided.

A Computational Method For Determining The Growth Rates Of Saline Water Drops., Robert Alexander Fletcher

Masters Theses

"A phenomenologica1 theory is presented which describes the growth or evaporation of cloud droplets containing dissolved NaCl. The main interest is in the early stages of growth. The Maxwell-Fuchs equation is employed with refinements to account for the high sa1t concentration in small droplets. A computer program is presented that ca1culates the growth time as a function of radius for cloud droplets nucleated with NaCl.

The growth times obtainable from the Maxwe11-Fuchs equation differ significantly from the growth times ca1culated using the refined Maxwell-Fuche equation for ambient relative humidities less than or equal to 100%. Growth times for droplets nucleated …

Charge Transfer Between H ˉIons And O₂ Molecules And D ˉIons And O₂ Molecules In The Ground State., Paul Edgar Chaplin

Masters Theses

"This thesis has been prepared in the style utilized by the Physical Review A. Pages 1-17 will be presented for publication in that journal. Appendices I, II, III, and IV have been added for purposes normal to thesis writing"-- Abstract, p. ii

…Y La Junta De Energía Nuclear, Habló, Aldemaro Romero Jr.

Publications and Research

No abstract provided.

Cross Sections For L2,3 Auger Emission In 22- To 300-Kev H+ + Ar Collisions, M. Eugene Rudd

M. Eugene Rudd Publications

Measurements of total and differential L_2,3 Auger cross sections for H⁺ + Ar collisions at 22 - 150 keV are presented. Additional values of these cross sections were calculated from data in earlier investigations by Volz and Rudd and by Crooks and Rudd up to 300 keV. Angular distributions are found to be isotropic. Over most of the energy range the total Auger cross sections are a factor of 2 smaller than predicted by Garcia's binary-encounter calculations.

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 …

Cross Sections For Photoionization Of The 6²P-Fine Structure Levels Of Cesium, John Daniel Jones

Doctoral Dissertations

"The cross sections for photoionization of excited cesium from the 6²P_3/2- and 6²P_1/2-fine structure levels have been measured using a triple crossed-beam apparatus. Two photon beams, one for excitation and one for ionization, impinge upon an atomic beam and produce ions at the point of intersection. The relative cross section is determined from a knowledge of the ion count rate and the relative photon flux of the ionization light. The results are normalized to available theoretical calculations and compared with recombination measurements in cesium plasmas. The present cross sections are found to decrease with …

Double Reflection Dips - From Grating Ruled Semiconductors, Le-Fu Teng

Doctoral Dissertations

"The double dips, previously observed by Fischer, Anderson, et al., which appeared in the reflection spectra of grating surfaces on the Te-doped semiconductors GaAs and InSb around the plasmon and phonon frequencies have been measured in more detail. In the plasmon region, several possible explanations of the phenomenon are discussed. A simple equation checked with the rigorous theory is proposed and is shown to fit the data well. In the phonon region, the extra dip is calculated and identified as being caused by surface phonons"--Abstract, page ii.

Surface Electromagnetic Waves With Damping I. Isotropic Media Ii. Anisotropic Media, Gary Shannon Kovener

Doctoral Dissertations

Paper 1: “Surface electromagnetic wave (SEW) dispersion curves are usually calculated using a simple equation derived from Maxwell’s equations and boundary conditions. When complex dielectric functions are used for the two media, the component of the propagation vector along the surface k_x becomes infinite as the frequency ω approaches the surface polariton frequency ω_s if ω is considered complex and k_x real. On the other hand, if k_x is considered complex and ω real, the dispersion curves bend back toward smaller k_x as ω approaches ω_s. We have previously demonstrated that both types …

Erratum: Radiative And Predissociative Lifetimes Of The A ²Σ+ State Of Oh, Richard A. Anderson, R. A. Sutherland

Physics Faculty Research & Creative Works

No abstract provided.

Spectroscopic Determinations Using Resonance Spin-Flip In 12C (P,P1) 12C And 50Ti (P,P1) 50Ti, Lee Robert Baumann

Masters Theses

No abstract provided.

A Direct Measurement Of The Ratio Of The Reaction Cross Sections For Two-Photon And Three-Photon Positron Annihilation In Aluminum And Silver, Robert Maurice Heavenrich

Masters Theses

The probability of annihilation of a positron with its antiparticle, an electron, is spin dependent. Since both particles have spin component one -half, there are two possible relative orientations of their spins they can either be aligned (parallel) in the ³S, triplet, state with total spin component │S_z│= ½ n - ½ n = 1 n or they can be opposite (antiparallel) in the ¹S; singlet, state with│S_z│= ½ n - ½ n = 0. To conserve energy and angular momentum, annihilation from the triplet state must result in the creation of an odd …

Electron Spin Resonance In Argon-Ion-Implanted Silicon, Keh Chang Chu, Weiler R. Hurren, Edward Boyd Hale, John Reigle

Physics Faculty Research & Creative Works

A new paramagnetic center with g = 2.0029 is observed, in both n- and p-type silicon after they are heavily implanted (higher than 1017 ions/cm2) with 150-keV argon ions. © 1973 American Institute of Physics.

Properties Of Microwave Cavities Containing Magnetic Resonant Samples, Kathy A. Rages, Robert E. Sawyer, Edward Boyd Hale

Physics Faculty Research & Creative Works

Properties of TE011 cylindrical, microwave cavities containing cylindrical samples of various radii and dielectric constants are calculated. The properties considered are the resonant frequency, quality factor (Q), relevant magnetic filling factor for spin transitions (ε), and a signal sensitivity factor (Qε) for a lossless sample. Sample sizes range from zero radius to full cavity radius with some experimental data on less than full length samples. The choice of dielectric constants ranges from one to sixteen. The data are presented in dimensionless form since they will be of use to other ESR experimentalists. It is shown that use of large samples …