Physical Sciences and Mathematics Commons^™

Plasma Line Measurements At Chatanika With High-Speed Correlator And Filter Bank, W. Kofman, Vincent B. Wickwar

All Physics Faculty Publications

In the spring and fall of 1978 we made an extensive series of plasma line and correlative observations with the Chatanika incoherent scatter radar. To make these measurements, we greatly modified the radar receiving system. In addition to enlarging the plasma line filter bank the most significant change was the incorporation of a high-speed correlator provided by the French. This was the first use of a correlator in a monostatic radar to obtain the intensity spectra of naturally occurring plasma lines. In this paper we develop the signal-processing theory that we use to obtain the plasma line intensities from these …

Design And Use Of A Computerized Test Generating Program, Edward Schaefer, Laurence A. Marschall

Physics and Astronomy Faculty Publications

An easy-to-use set of programs for the computerized generation of multiple-choice and easy examinations in an introductory astronomy course is described. The programs allow the user to establish files of test questions and to rapidly assemble printed copies of examinations suitable for photocopying. Written in ALGOL for a Burroughs B6700 computer, the programs can, in principle, be implemented on large mainframe computers or on microcomputers of a size increasingly available to physics departments. The advantages and costs of computerized test generation are discussed.

Type I Radar Echoes From Theequatorial Electrojet With Double Peaked Doppler Spectra, Bela G. Fejer, D. T. Farley, P. Johnston, B. B. Balsley

Bela G. Fejer

Normal type 1 radar echoes obtained from relatively large zenith angles have a power spectrum with a single narrow peak whose Doppler shift corresponds approximately to the acoustic velocity in the medium. On some occasions, however, this single maximum splits into two distinct peaks, separated in phase velocity on one occasion by 270 m/s. This bifurcation is most easily observed at large zenith angles during daytime when a narrow antenna beam is used. It has also been seen in a daytime experiment in which radars at Jicamarca and Huancayo simultaneously probed the same region from two different radar zenith angles. …

Comment On “Cancellation Of Internal Forces”, Harry A. Brown

Physics Faculty Research & Creative Works

No abstract provided.

Water And Ice Nucleation Sites From Ion Implantation Of Silicon, William H. Stlnebaugh, Don M. Sparlin, James L. Kassner

Physics Faculty Research & Creative Works

Ion implantation has a substantial effect on the heterogeneous nucleation of water and ice. An enhancement of water nucleation and a suppression of ice nucleation occurred for samples of silicon implanted with ions of various species and dosage. These effects were noticeable only for samples implanted with ion doses approaching or exceeding the critical dose necessary to produce amorphous silicon. The behavior of the water droplet and ice crystal growth can be related to the amount of ion produced damage to the substrate surface. The nature of the damage can be controlled by variation of the incident ion species, dose, …

Autooscillations And Nonlinear Anelasticity, Manfred Wuttig, Tetsuro Suzuki

Materials Science and Engineering Faculty Research & Creative Works

In conclusion it can be stated that a novel phenomenon, a mechanical auto oscillation, has been described theoretically and shown to exist experimentally. These auto oscillations occur when a nonlinear anelastic solid is forced into large amplitude oscillations in the vicinity of a martensitic transformation. They manifest themselves as a low frequency auto modulation of the a martensitic transformation. They manifest themselves as low frequency auto modulation of the forced vibration of such a solid. © 1980.

Total Penning Ionization Cross Sections Of Cd And Zn For He(2 ³S1) Atoms, D. W. Fahey, William F. Parks, Laird D. Schearer

Physics Faculty Research & Creative Works

The total Penning ionization cross sections for Cd and Zn for He(2 3S1) atoms have been measured. The method used was that of Penning ion collection from a vapor cell through which a He(2 3S1) beam was passed. The beam energy was 66 meV with a velocity spread of 45%. The measured cross sections were 106(±22) and 35(±7) Å2 for the Cd and Zn targets, respectively. © 1980 American Institute of Physics.

Solid State Phase Transitions And Molecular Reorientation In Ortho-Carborane And Para-Carborane: An Isomer Effect, Peter A. Beckmann, Amos J. Leffler

Physics Faculty Research and Scholarship

The proton nuclear spin-lattice relaxation times at 30 MHz have been measured for ortho- and paracarborane between 170 and 310 K and between 210 and 320 K, respectively. Para-carborane undergoes solid-solid transitions at about 300 and 238 K while the ortho isomer shows only one transition at about 265 K. The details of the phase transitions are discussed and molecular reorientation in the isomers is compared.

Proton Spin-Lattice Relaxation In Meta-Carborane, Peter A. Beckmann, Armin Wendel

Physics Faculty Research and Scholarship

No abstract provided.

A Deuterium Nuclear Magnetic Resonance Study Of Chain Disorder In Lamellar Potassium Palmitate: The Effect Of Long And Short Chain Guests, Peter A. Beckmann, E. E. Burnell, M. A. Heldman, K. R. Northey, T. P. Higgs

Physics Faculty Research and Scholarship

The deuterium magnetic resonance spectra of lamellar phases of host perdeuterated potassium palmitate mixed with varying amounts of guest protiated potassium octanoate and behenate and 86.3 mol% D₂O are reported. At higher temperatures, the short chain guests give rise to more fluidity and the long chain guests give rise to less fluidity towards the end of the host chain. At low temperatures there are changes in the interaction between the polar head group and the water which depend on sample composition. The transition from the lamellar phase to the low temperature gel phase is investigated and in some …

A Graphical Method For Calculating First Order Transition Matrices For Open-Shell Atoms In The Random Phase Approximation, Anthony F. Starace, Siamak Shahabi

Anthony F. Starace Publications

A graphical procedure is presented for calculating first order transition matrices for a general (open-shell) atom. The first order transition matrix may be used to calculate matrix elements of a general one-body operator of rank λ in orbital space and σ in spin space. In the random phase approximation we obtain a set of N + N′ coupled differential equations for N final state radial functions and N′ initial state radial functions which completely determine the first order transition matrix for an atomic system having N final state channels. (The relation of N′ to N is dependent on the atomic …

Improved Characterization Of Silicon-Silicon-Dioxide Interfaces, Pin Su

Dissertations, Theses, and Masters Projects

Silicon is the heart of modern semiconductor devices. The dominance of Si in semiconductor technology depends on the superior quality and properties of thermally grown SiO(,2) compared with the oxide that can be placed on any other semiconductor. For this reason, Si-SiO(,2) interface has been an interesting and important research subject for many years.;The well established quasistatic and conductance methods used in the study of the Si-SiO(,2) interface are improved by using (i) an effectively thin composite insulator, (ii) low carrier concentration substrates, and most importantly (iii) low-level illumination at a wavelength that creates electron-hole pairs. Accurate measurements of both …

Most Probable Magnetohydrostatic Equilibria For Tokamaks And Reversed Field Pinches, John Joseph Ambrosiano

Dissertations, Theses, and Masters Projects

The determination of magnetohydrostatic equilibria usually requires that two of the equilibrium functions be given. as there is usually no a priori basis for specifying the form of these two functions, the functions and the equilibria they determine may be considered random.;In this dissertation, the author reviews a recent statistical method for determining the equilibrium of an axially symmetric cylindrical plasma which is most probable (in the maximum entropy sense) given four global constraints (i.e., energy, magnetic helicity, longitudinal magnetic flux, and longitudinal current flux). Previous results from this model have been limited to non-negative random equilibrium functions (B(,z), J(,z), …

Forbidden Lines Of Np^Q Ions. I. Detailed Balance And Line Intensity Ratios, Menas Kafatos, J. P. Lynch

Mathematics, Physics, and Computer Science Faculty Articles and Research

Ground state forbidden transitions of np^q ions of C, N, 0, Ne, Mg, Si, S, and Fe can provide important information on the state of cosmic ionized gases. Wavelengths of these lines are in the far- and near-UV visible and near-- and far-IR regions of the spectrum. The line intensity ratios of particular transitions in q = 2, 4 ions can provide information on the temperature of the gas and in q = 3 ions information on the density of the gas. In the present work we have tabulated the line intensities of 95 transitions of these ions, which include …

A Molecular Dynamics Study Of The Stability Of Small Prenucleation Water Clusters, Tze-Shan Chen

Doctoral Dissertations

"The dynamical stability and internal energy distribution of prenucleation water embryos have been studied by the molecular dynamic's method. Water clusters containing either five or twenty molecules were chosen to represent prenucleation embryos of small or intermediate size. A central force potential model of water which allows energy to be absorbed into intramolecular modes so that bond lengths and bond angles could adjust to changes in molecular environments was employed to describe the interaction between all pairs of atoms. The motion of the molecules was followed for extended time periods (of the order of several picoseconds) at each of a …

Nickel Carbide: Its Formation And Characterization By Transmission Electron Diffraction, Auger Electron Spectroscopy And Electron Spectroscopy For Chemical Analysis, J. Kleefeld, L. L. Levenson

Physics Faculty Research & Creative Works

Nickel carbide (NiC3) films are formed by the carburization of nickel films in CO at 350°C. The presence of Ni3C is demonstrated by transmission electron diffraction. The carbon Auger electron signal of Ni3C is identical with the carbon Auger spectra attributed to Ni3C by previous authors. The position of the C 1s electron spectroscopy for chemical analysis peak is within 1 eV of the C 1s peak produced by graphite. The grain size of polycrystalline Ni3C is significantly larger than the grain size of the nickel film from which it is grown. © 1979.

Rates Of Dissociative Attachment Of Electrons To Excited H2 And D2, J. M. Wadehra

Physics and Astronomy Faculty Research Publications

Calculations are reported of the contributions of the lowest 2Σ+ u and 2Σ+ g resonant states to the rates of dissociative attachment of electrons to H2 and D2. For all electron temperatures, the rate is significantly enhanced by vibrational and rotational excitation of the initial molecule. Typically, for an electron temperature of 1.5 eV, the attachment rates for various (v, J) levels are, in cm3 sec−1, 5.4×10−15 for (0,0), 7.2×10−11 for (0,20), and 7.8×10−9 for (8,0), for H2; and 4.5×10−17 for (0,0), 1.4×10−14 for (0,20), and 6.0×10−9 for (11,0), for D2.

Comment On The Negative Ion States Of Fluorobenzenes, K.D. Jordan, Paul Burrow

Paul Burrow Publications

It is contended that several assignments given by the model employed by Frazier et al¹ should be reconsidered especially of the anion states aniline phenol and anisole. The symmetry assignments of the anion states of fluorobenzene and p difluorobenzend as given by this model are incorrect.

Saturated Solar Ponds: Modified Equations And Results Of A Laboratory Experiment, Markus Karl Rothmeyer

Physics & Astronomy ETDs

The diffusion equation for salt gradient solar ponds has been modified to include the Soret effect (a thermal cross-effect due to the temperature gradient). The contribution of the Soret effect to the diffusion flux of salt is shown to be on the order of 4% in the winter and 28% in the summer for the UNM NaCl solar pond. The traditional stability criterion for solar ponds remains practically unchanged by the Soret effect. However, the contribution of non-constant properties (diffusion coefficient, thermal diffusivity and viscosity)--which have been neglected so far--seems to be significant. Saturated solar ponds are described by a …

Electron Drift Velocities In N2, Co2, And (N 2+Co2) Laser Mixtures, Rafael A. Sierra, Howard L. Brooks, Kaare J. Nygaard

Physics Faculty Research & Creative Works

A time-of-flight technique has been used to obtain electron drift velocities in N₂, CO₂, and N₂-CO₂ mixtures covering the E/N range 3-93 Td. In the case of the pure gases, excellent agreement with previous work is obtained over the entire E/N range. The mixtures, which are of laser importance, have not been studied previously.

Magnetic Ordering And Exchange Interactions In The Rare-Earth Gallium Compounds R Ga2, T.-H. Tsai, David J. Sellmyer

David Sellmyer Publications

Magnetic ordering and indirect exchange interactions were studied in the series of hexagonal rare-earth intermetallic compounds R Ga₂, where R denotes Ce, Pr, Nd, Gd, Tb, Dy, Ho, and Er. The magnetic susceptibility (χ) of polycrystalline samples was measured at low fields, from 1.5 K to about 300 K; the magnetization (M) versus applied magnetic field (H) of these polycrystalline samples and a HoGa₂ single crystal was measured up to 80 kOe at low temperatures; the resistivities (ρ) of CeGa₂, GdGa₂, DyGa₂, and HoGa₂ were measured …

The Hanle Effect In Penning-Excited Ions, D. W. Fahey, William F. Parks, Laird D. Schearer

Physics Faculty Research & Creative Works

A thermal beam of helium (23S1) metastable atoms was used to excite coherently the 2P3/2 levels of Ca, Sr and Ba in a Penning ionizing collision. The coherent excitation of the ions appears as a linear polarization of the optical emission from the excited ions. The degree of linear polarization is 5.5, 3.5 and 0.5% for Ca, Sr and Ba, respectively, with the polarization parallel to the beam direction. Hanle effect signals from the 2P3/2 level of Sr were observed and the radioactive decay rate measured.

Conductive Strontium Titanate Layers Produced By Boron-Ion Implantation, Connie M. Cooper, P. S. Nayar, Edward Boyd Hale, Robert Gerson

Physics Faculty Research & Creative Works

The ion implantation of boron has been found to be an effective method for increasing the conductivity of strontium titanate. A highly conductive layer was formed by implantations at doses of 3.6x1016 to 1.0x1017 ions/cm2, using an accelerating voltage of 100 kV, corresponding to a boron range of about 300 nm. The conductivity of the implanted layer was found to be further enhanced by about four orders of magnitude after annealing at 225 °C. The surface resistivity attained was typically 1000 Ω/square at room temperature. The resistance increased with rising temperature between 77 and 500 K. All samples were found …

The Neutron Total Cross Section Of 208Pb, Lawrence J. Satkowiak

Masters Theses

No abstract provided.

Determination Of Energy Levels & Oscillator Strengths Of 2% Nd:Y2o3, Kung-Chuan Shao

Masters Theses & Specialist Projects

The absorption spectrum of 2% Nd:Y₂O₃ has been obtained at room termperature. It has been used to determine the crystalline energy levels.

Through counting the number of Stark components, degeneracies have been determined for oscillator strength calculations.

Overlapping absorption lines were analyzed into their components.

Oscillator strengths have been measured for those well-identified and analyzed transitions in the variable and near ultraviolet regions of the 2% Nd:Y₂O₃ absorption spectrum.

Low-Energy Collisions Of D+ With D And He++ With He, J. M. Wadehra

Physics and Astronomy Faculty Research Publications

Quantum-mechanical calculations for differential cross sections and various transport cross sections describing the thermal-energy collisions of D+ with D and He2+ with He are presented. Lowest-order Viehland-Mason theory is used to calculate mobility of D+ in D. The zero-field mobility at 77, 303, and 10000 K is, in units of cm2V−1s−1, 10.5, 7.0, and 2.1, respectively.

Lasers In Energy Research, Kaare J. Hygaard, Howard L. Brooks, Rafael A. Sierra, Stephen R. Foltyn

UMR-DNR Conference on Energy

No abstract provided.

The Moral Equivalent Of Business As Usual, Harry A. Brown

UMR-DNR Conference on Energy

No abstract provided.

Dissociative Attachment And Vibrational Excitation In Low-Energy Collisions Of Electrons With H2 And D2, J. N. Bardsley, J. M. Wadehra

Physics and Astronomy Faculty Research Publications

A semiempirical analysis is made of the contributions of the two lowest resonant states to dissociative attachment and vibrational excitation in low-energy collisions of electrons with H2 and D2. The resonance models are based both on ab initio calculations and on fits to experimental data. The dissociative-attachment cross section near threshold is enhanced significantly by vibrational or rotational excitation of the initial molecule. Near 10 eV, contributions from both resonances are required to explain the observed cross sections for vibrational excitation.

Equatorial Electricfields During Magnetically Disturbed Conditions, 1. The Effect Of The Interplanetary Magneticfield, Bela G. Fejer, C. A. Gonzales, D. T. Farley, M. C. Kelley, R. F. Woodman

Bela G. Fejer

Radar measurements of E and F region drift velocities have been used to look for correlations between changes in equatorial electric fields and the interplanetary magnetic field (IMF). The east-west component of the IMF appears to be unimportant, but the north-south component has some effect; rapid reversals from south to north are sometimes correlated with reversals of the equatorial east-west electric field during both daytime and nighttime. This is not always true, however, the IMF may reverse without any apparent effect at the equator. Furthermore, large equatorial field perturbations are sometimes observed when the IMF Bz is large and southward …