Physical Sciences and Mathematics Commons^™

Elevated Electron Temperatures In The Auroral E Layer Measured With The Chatanika Radar, Vincent B. Wickwar, C. Lathuillere, W. Kofman, G. Lejeune

All Physics Faculty Publications

An extensive series of spectral measurements has been made in the auroral E region with the Chatanika incoherent scatter radar. Becasue of the small scale length for variations of electron density, temperatures, and ion-neutral collisions we used the operating mode with the best possible range resolution—9 km. About 5% of the time the data exhibited an unusual spectral shape that was most pronounced at 105 and 110 km. Instead of being almost Gaussian with only a small hint of two peaks, the spectra are much wider, with two well-developed peaks. After carefully considering the validity of the measurements and their …

F-Region East-Westdrifts At Jicamarca, Bela G. Fejer, D. T. Farley, C. A. Gonzales, R. F. Woodman, C. Calderson

Bela G. Fejer

F region east-west drifts have been measured at Jicamarca for almost 10 years, using incoherent scatter. The drifts are westward during the day and eastward at night. The daytime drift velocities are about 50 m/s and change very little with season or solar cycle. The evening reversal occurs at about 1600 local time throughout the solar cycle. The maximum nighttime eastward drifts are about 105 and 130 m/s during solar minimum and maximum, respectively. The daytime and nighttime drifts show very litle variation with magnetic activity. These Jicamarca incoherent scatter results (especially the reversal times) differ appreciably from results obtained …

Modern Spectroscopy With A Spectrometer By The Optogalvanic Effect, Kenneth Arnett, Richard A. Anderson, Ralph William Alexander

Physics Faculty Research & Creative Works

An Experiment Involving the Optogalvanic Effect Suitable for the Advanced Physics Laboratory is Described. This Experiment Complements the Usual Basic Experiment in Atomic Spectroscopy Where Spectra Are Recorded on Photographic Film with a Spectrograph or with a Monochromator and Photomultiplier. the Optogalvanic Effect Used the Atoms Being Studied as the Detector and a Tunable Dye Laser as the Source. Linewidths Observed Are Those of the Dye Laser that Are Considerably Smaller Than Those Obtained with the Usual Laboratory Monochromator. the student is Introduced to the Techniques of Spectroscopy with Pulsed Dye Lasers and to a Spectrum for Which LS Coupling …

Excitation Transfer In Ion Rydberg-Atom Collisions, R. (Ronald) E. Olson

Physics Faculty Research & Creative Works

Recently, electron-loss cross sections were presented by Kim and Meyer [Phys. Rev. Lett. 44, 1047 (1980)] for 40 keV/amu N3+ + H**(n) collisions which scaled as n3.12, where n is the principal quantum number of the excited H0. Such results are in contrast to an n2 scaling predicted by classical and first-Born theoretical methods. Our calculations indicate that a major component of the experimentally observed ion signal was due to Stark ionization by deflector grids of highly excited H0 produced in excitation-transfer collisions. Inclusion of the excitation process in a theoretical interpretation reveals qualitative agreement between theory and experiment and …

Hall Effect At High Pressure In (Snxeu1-X)1.2mo6s8, Paul D. Hambourger, C. Y. Huang, H. L. Luo

Physics Faculty Publications

No abstract provided.

Autooscillations In Zinc, Manfred Wuttig, Alex Aning, Tetsuro Suzuki

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Excitation Transfer Collisions And Electron Seeding Processes In A Resonantly Excited Sodium Vapor, D. J. Krebs, Laird D. Schearer

Physics Faculty Research & Creative Works

A dense sodium vapor in a high-pressure buffer of argon has been simultaneously excited by short (4 ns) laser pulses from two lasers: the first tuned to one of the D line transitions at 589 nm and the second tuned to the photoionization threshold of the 3p states near 406 nm. The temporal evolution of the system was studied with and without the photoionizing laser pulses. At early times (∼100 ns) excited state populations are determined by energy transfer collisions between two laser-excited 3p atoms while the ion/electron density is controlled by super elastic heating of "seed" electrons followed by …

Synchronized Slide-Tapes In The Physics Laboratory, Loren Quan

University of the Pacific Theses and Dissertations

Media play a large part in most of our daily lives. We watch television; we go to the movies; we listen to the radio. For years educators have been adapting media-related technological advancements for the purpose of teaching in the classroom. Here at the Physics Department of the University of the Pacific, we have adapted the medium of synchronized slide-tapes for use in the laboratory component of our calculus-based introductory physics course.

A Numerical Investigation Of A Certain One-Dimensional Ising Model, Jimmy Green

Masters Theses & Specialist Projects

The model is a linear chain in which each spin interacts with its 2r nearest neighbors, the interaction energy being proportional to 1/r. Using a method similar to that of Montroll, the partition function of the model in the thermodynamic limit is shown to be related to the largest eigenvalue of a certain matrix. The largest eigenvalue of the matrix is determined numerically for 3 < r < 12.

Also, a correct method is demonstrated for evaluating an improper limit of the model, in which the interaction range is set to the chain length before the limit of an infinite number of spins is …

Ultrasonic Determination Of Thermoelastic Properties Of Stressed Solids, Engmin J. Chern

Dissertations, Theses, and Masters Projects

We present a thermoelastic derivation of ultrasonic waves propagating in a solid in which an applied homogeneous stress is superimposed on a nonzero initial stress. We also derive the temperature dependence of the elastic coefficients and the linear relationship between the applied stress and a newly defined parameter--the thermal acoustic constant. The stress acoustic constant is defined and its relationship to the acoustic natural velocity is discussed. Experimental considerations pertinent to the ultrasonic measurement techniques used in the investigation are described. The results of the stress-strain and thermal strain experiments verify the predictions of the theory. Finally, we derive an …

Phosphorus-31 Knigh Shifts In Amorphous Nickel-Phosphorus And Nickel-Cobalt-Phosphorus Alloys, Paul Stuart Gustafson

Dissertations, Theses, and Masters Projects

Amorphous alloys of the form Ni(,1-x)P(,x) and (Ni(,1-y)Co(,y))(,1-x)P(,x) were prepared by two methods, electroplating (EP) and electroless deposition (EL). Two metastable phases of differing physical densities and NMR properties were noted, and analysed by measurement of the Knight Shifts, relaxation times, physical densities, etc. A comparison is made between the data and a hybridized band model which yields an expression for the enhanced susceptibility of the phosphorous valence band.

The Structure Of Axisymmetric Turbulence, Charles W. Smith

Dissertations, Theses, and Masters Projects

A wide range of laboratory and naturally occurring plasmas are frequently attributed a fluid description and as such, demonstrate turbulent flows. We will investigate a variety of forms which may be taken by the correlation functions of these turbulent flows. The most commonly discussed isotropic symmetry is not generally applicable since most systems of interest have been shown to be strongly anisotropic. This thesis will develop an axi-symmetric description from which the magnetic helicity may be extracted together with its spectrum. This description will be compared to the form taken by axi-symmetric, helical Navier Stokes turbulence which will also be …

Nmr In Amorphous Vanadium Alloys, Larry Mattix

Dissertations, Theses, and Masters Projects

Amorphous alloys of VAl and VSi have been prepared by a process of r.f. sputtering onto cryogenic substrates. The Nuclear Magnetic Resonance has been examined in an effort to understand how the electronic structure of these amorphous alloys compares to that of the corresponding crystalline alloys, and to extend the study of the electronic properties of these alloy systems into composition ranges where the crystalline alloys do not exist, because of solubility limits.;The Al('27) and V('51) Knight shifts were measured at 77(DEGREES)K and 300(DEGREES)K, for Al concentrations extending from 15 to 85 atomic percent, in amorphous VAl. The results are …

Boron Implanted Strontium Titanate, Connie Macdonald Cooper

Doctoral Dissertations

"Single crystals of strontium titanate implanted with boron were found to have highly conductive surface layers. The effects of varying dose from 10¹⁶ to 10¹⁷ ions/cm², implantation voltage from 50 to 75 keV, and annealing conditions on the room temperature surface resistance and Hall mobility are presented in this study. A major result is that, for the most part, variation of the implantation voltage did not have a major effect on the sheet resistances obtained by boron implantation of strontium titanate, while dose and annealing conditions have major effects.

Doses of 5 X 10¹⁶ ions/cm …

Kinetic Processes In A High Pressure Laser Generated Plasma, Danny Joe Krebs

Doctoral Dissertations

"A dense sodium vapor in a high-pressure noble buffer has been simultaneously excited by short (4 ns) laser pulses from two lasers: ii the first tuned to one of the 'D' line transitions and the second tuned to either the photoionization threshold of the 3p states near 406 nm or to a higher level 3p-nd resonance. The population densities of the excited levels of atomic sodium were measured with temporal resolution by absolute intensity measurements of excited state fluorescence. At early times (~100 ns), excited state populations are determined by energy transfer collisions between two laser-excited 3p atoms while the …

A Study Of Leslie Model Under Stochastic Environments, Kamran Shaukat

Dissertations and Theses

The prediction and analysis of changes in the numbers of biological populations rest on mathematical formulations of demographic events (births and deaths) classified by the age of individuals. The development of demographic theory when birth and death rates vary statistically over time is the central theme of this work. A study of the standard Leslie model for the demographic dynamics of populations in variable environments is made. At each time interval a Leslie matrix of survival rates and fertilities of a population is chosen according to a Markov process and the population numbers in different age classes are computed. Analytical …

Triple Gamma Directional Correlations In The Decay Of Europium-154, Gary Lewis

Gary C. Lewis

The ('154)Eu nucleus decays by beta emission to an excited state of the ('154)Gd nucleus. The resulting ('154)Gd nucleus decays to its ground state by emission of gamma rays. One series of gamma rays emitted in this process is a cascade of energies 723 keV, 873 keV, and 123 keV. The 873 keV gamma ray is a mixture of E2 and M1 radiation. The mixing ratio of this transition has been measured using the triple gamma directional correlation technique. The experiments used a planar geometry with one angle fixed at 90 degrees. Two Ge(Li) detectors and one NaI(T1) detector were …

The Dependence On Zenith Angle Of The Strength Of 3-Meter Equatorial Electrojet Irregularities, H. M. Ierkic, Bela G. Fejer, D. T. Farley

Bela G. Fejer

Radar measurements in Peru were used to deduce the zenith angle dependence of the scattering cross section of plasma irregularities generated by instabilities in the equatorial electrojet. The irregularities probed by the 50 MHz Jicamarca radar had a wavelength of 3m. The cross section for the type 2 irregularities was isotropic in the plane perpendicular to the magnetic field, while the cross section for the stronger type 1 irregularities varied with zenith angle at a rate of approximately 0.3 dB/degree; the horizontally traveling waves were more than 100 times stronger than those traveling vertically.

Improving Physics Teaching, Robert Fuller

Robert G. Fuller Publications

I began this editorial with a desire to take up battle against the recent ills of physics teaching. I paused to peruse the AAPT reprint book, 50 Years on Teaching Physics, edited by Melba Phillips.

High Flux Beam Source Of Thermal Rare-Gas Metastable Atoms, D. W. Fahey, William F. Parks, Laird D. Schearer

Physics Faculty Research & Creative Works

A high-flux beam source has been constructed for the production of helium, neon and argon metastable atoms. The source is a DC electric discharge maintained in an expanding gas. A metastable flux of 3.5*1014, and 7.2*1013 atoms s-1 sr-1 has been achieved with most probable energies of 66, 72 and 74 meV for the helium, neon and argon sources, respectively. Time-of-flight measurements showed the widths of the respective velocity distributions to be 45%, 27% and 27%.

Stopping Power Of Matter For Alpha Particles At Extreme Relativistic Energies, P.T. Leung, M. L. Rustgi, J. E. Turner

Physics Faculty Publications and Presentations

The stopping power of matter for alpha particles at extreme relativistic energies has been calculated by incorporating the charge form factor. A table is presented for aluminum, copper, and lead. It is found that at the highest energies considered, inclusion of form factor reduces the mass stopping power by about 6-8% in comparison with that predicted by Bethe's relativistic formula.

Thermal Decomposition Kinetics Of Asf5-Doped Polyacetylene In Vacuum, T. Inoue, J. E. Osterholm, H. Yasuda, L. L. Levenson

Physics Faculty Research & Creative Works

Electrical conductivity measurements, mass spectra of desorbing species, and ESCA surface analysis are reported for AsF5-doped polyacetylene heated between 50 and 130°C in vacuum. All measurements indicate first-order decomposition kinetics with activation energies between 13 and 20 kcal mole-1. Decomposition leads to the desorption of AsF3 and F2. Metallic arsenic remains in the polyacetylene as a decomposition by-product.

Trends In The Theory Of Atomic Photoionization, Anthony F. Starace

Anthony F. Starace Publications

For VUV photon energies, detailed theoretical understanding of the photoionization process has been achieved for the case of a single electron ionized from one of the outer subshells of a closed-shell atom. This understanding is based qualitatively upon a few properties of realistic atomic central potentials and quantitatively upon a few distinct types of electronic interactions known generically as particle-hole interactions. Current theoretical research is mainly directed at understanding a broader class of atomic photoionization phenomena involving, e.g., open-shell atoms, electronic interactions not of the particle-hole class, real two-electron processes, and external electric and magnetic fields.

High Resolution Laser Absorption Spectroscopy Of Ozone Near 1129.4 Cm-1, Lawrence N. Majorana

Physics Theses & Dissertations

A Beer's Law experiment was performed with a tunable laser to determine self broadened line shape parameters of one infrared absorption ozone line in the v1 band for ten pressures from 0.26 to 6.29 Torr at 285K. SO₂ line positions were used for wavelength calibration. Line shapes were iteratively fitted to the Voigt function at a Doppler width of 29.54 MHz (HWHM) resulting in values for the integrated line• strength, ( S), of (0.144 +/- 0.007 ) x ·10^-20 cm-1/molecule cm-2, line center frequency, (υ_ο) of 1129.426 cm-1 and the Lorentzian contributions to half width, (α …

An Experiment In Discovery, Daniel J. Steck

Physics Faculty Publications

No abstract provided.

Sound Absorption In N2-H2O Gas Mixtures At Elevated Temperatures, Roger W. Meredith

Physics Theses & Dissertations

Sound absorption measurements were conducted in N₂ -H₂O gas mixtures at 297, 343, and 387 Kelvin to determine the location of the vibrational relaxation peak of nitrogen on the frequency/pressure, (f/P), axis as a function of humidity and temperature. At low humidities the best fit of the data is to a linear relationship between (f/P)_max and humidity (h) yields a slope of 1 .84 X 10⁴ Hz/ atm mole fraction at all three temperatures. The slope is the same as that reported by Zuckerwar and Griffin (2.00 X 10⁴ Hz/atm mole fraction) but is …

Dielectric Saturation In Dipolar Fluids. I. The Single-Molecule Distribution Function, John D. Ramshaw

Physics Faculty Publications and Presentations

The functional-derivative formalism is used to investigate the form of the equilibrium single-molecule distribution function n(1) in a finite fluid system of rigid polar molecules subjected to a strong external electric field that varies slowly with position. The investigation is based on the assumption that the long-range asymptotic behavior of the direct correlation function is independent of the external field, and is hence the same as in the unperturbed fluid. This assumption implies that n(1) has the form of a single-molecule Boltzmann factor in which the interaction energy is that of a deformable quasidipole with the local Lorentz electric field …

Electrostatic Tem Studies Of Magnetic Domains In Thin Iron Films, Hideaki Karamon

Dissertations and Theses

An electron microscope with electrostatic lenses was used for high resolution studies of magnetic domains in thin iron films.

Observation methods used to determine the directions of local magnetization in iron thin films were the Lorentz method and the Foucault method.

We studied how Bloch line-crosstie pairs and crosstie main walls behave in applied, in-plane magnetic fields. We found that crosstie main walls remain unchanged until crosstie density goes nearly to zero when the field is applied perpendicular to the main wall. A twisted type of domain appears where crossties disappear.

10 Kw Per Capita, Harry A. Brown

UMR-MEC Conference on Energy / UMR-DNR Conference on Energy

The rate of energy use in the U.S. is discussed. Possible savings in the principal areas of use are considered. The conclusion is that significant reductions could be made in five to ten years without new technology, but are not likely under present conditions.

Computed Cross Sections For Electron Transfer In Ba+ + Ba+ Collisions , Stanley J. Sramek, J.H. Macek, Gordon A. Gallup

Gordon Gallup Publications

Cross sections have been computed for the electron-transfer process Ba⁺+Ba⁺→Ba+Ba⁺⁺, for collision energies ranging from 25 to 500 keV. The straight-line classical-trajectory method has been used, with basis functions obtained by the multiconfiguration valence-bond method. Several numerical procedures applicable to future treatments of similar large systems were developed. The maximum cross-section value is found to be around 27π a₀² (2.4 × 10^-15 cm²), and occurs near collision energy 500 keV. The system's transient behavior has also been studied in detail during the collision, and it has been found that …