Physical Sciences and Mathematics Commons^™

1/N Expansions For Two-Electron Coulomb Matrix Elements, Gordon W. F. Drake, R. N. Hills

Physics Publications

The study of 1/n expansions for various atomic matrix elements, where n is the principal quantum number, plays an important role in the theoretical foundations of the quantum defect method. The paper develops an expansion in powers of 1/n 2 for hydrogenic boundstate wavefunctions which can be used to calculate 1/n expansions of matrix elements. The 1/n expansions of the two-electron direct and exchange Coulomb integrals are evaluated as an example. © 1993 IOP Publishing Ltd.

Angular And Radial Correlation In Doubly Excited Systems When 1 ≤ Z ≤ 4. The 2p2 3p State, D. R. T. Keeble, K. E. Banyard, Gordon W. F. Drake

Physics Publications

The angular and radial components of electron correlation have each been examined in detail for the discrete 2p2 3P states of H-, He, Li+ and Be2+. These doubly excited systems were described by highly accurate explicitly correlated wavefunctions. The analysis involved the use of angular Coulomb holes, changes in the one- and two-particle radial density distributions and several angular and radial expectation values. Additionally, various statistical correlation coefficients were used which emphasized, in turn, angular and radial correlation properties in different regions of the two-particle density. The angular holes and related properties showed a clearly defined inverse-Z effect for He …

Erratum: Variational Calculation For The Ground State Of Lithium And Qed Corrections For Li-Like Ions (Physical Review A (1993) 48, 6 (4803)), D. K. Mckenzie, Gordon W. F. Drake

Physics Publications

No abstract provided.

Erratum: Energy Corrections Of Order Mc2Α6 In Α In Helium (Physical Review A (1993) 48, 6 (4804), Gordon W. F. Drake, I. B. Khriplovich, A. I. Milstein, A. S. Yelkhovsky

Physics Publications

No abstract provided.

Energy Corrections Of Order Mc2Α6lnα In Helium, Gordon W. F. Drake, I. B. Khriplovich, A. I. Milstein, A. S. Yelkhovsky

Physics Publications

Quantum-electrodynamic corrections of O(mc2α6lnα) to the electron-electron interaction in helium are evaluated for several states. The additional energy shift, which is an order of α smaller than the leading Araki-Sucher terms, raises the predicted energy of the 1s2s 1S0 state by 2.49 MHz to -960 332 039.43(18) MHz relative to He+(1s). The new value significantly alters the comparison with recent high-precision experiments. © 1993 The American Physical Society.

Electromagnetism, Yimin Wang, Clifton Keller

All Books

No abstract provided.

On The System Of Diffuse Interstellar Bands At 5844 And 5850 Å, J Krelowski, Theodore P. Snow, J Papaj, C G. Seab, B Wszolek

Physics Faculty Publications

Two neighboring diffuse interstellar bands (DIBs) at 5844 and 5850 Å are shown to be of different origin. The presence or absence of the 5844 DIB is related to the ratio of the two prominent DIBs at 5780 and 5797 Å as well as to the nature of the ultraviolet extinction curve. The 5844 Å DIB is very sensitive to the extinction, being completely absent in cases where the far-UV extinction is low. This suggests that the carrier is destroyed by photons having energies above 11 or 12 eV. The 5850 Å DIB correlates very well with the well-studied DIB …

Magnetic Multilayers: Quasiclassical Transport Via The Kubo Formula, Horacio E. Camblong

Physics and Astronomy

A real‐space quantum approach, based on the Kubo formula, is used to describe the quasiclassical transport behavior of metallic multilayers. We emphasize the differences between the cases of current in the plane of the layers, for which size effects play a dominant role and current perpendicular to the planes, for which we provide several proofs that the so‐called series resistor model holds for all length scales.

The Force On A Sphere In A Tightly Focused Laser Beam, Marc Knudson

Honors Theses, 1963-2015

An investigation of the trapping force on a sphere in a tightly focused laser beam is carried out using a geometrical optics approximation. This calculation generalizes earlier work by allowing the spheres to be located off the beam axis. Additionally, a fifth-order, instead of zeroth-order, Gaussian approximation is used, and beam polarization is explicitly taken into account. The results suggest an interesting experiment, involving a driven damped harmonic oscilator system, which could be performed to test the validity of the theory. This experiment will be the focus of a future study.

A Track Physics Retrospective, Robert Katz

Robert Katz Publications

Many condensed matter dosimeters and detectors respond to the perspectives of track physics, a parametric model which relates their response to gamma rays to their response to heavy ions through the radial distribution of dose about a heavy ion’s path. Most dosimeters are treated as 1-hit detectors, a classification which includes emulsions, scintillators, TLDs, the Fricke dosimeter, alanine, and some biological substances: enzymes and Eschericia coli, among others. We have discovered many hit detectors. An extended model describes the killing, transformation, and mutation of biological cells after gamma and heavy ion irradiation. A detector is treated as a black box, …

Tables Of Coincidence Orientations For Ordered Tetragonal L Lo Alloys For A Range Of Axial Ratios, Abha Singh, Alexander H. King

Alexander H. King

In this paper we develop and apply techniques for computation of CSL, DSCL and step-vector data for grain boundaries in tetragonal materials for a range of axial ratios. This has application to L10 alloys including TiA1, which is a candidate for lightweight high-temperature structural applications. Our results are compared with others and found to be more accurate and complete. We provide data for a wider range of axial ratios than those considered by previous workers. We have also derived equivalent quaternions for tetragonal crystals in tetragonal-crystal coordinates and listed conditions for selecting a unique reduced rotation in tetragonal-crystal coordinates so …

A Geometrical Rationalization Of The Special Properties Of The 14° [001] Grain Boundary In Yba2cu3o7−Δ, Alexander H. King, Abha Singh

Alexander H. King

14° [001] tilt grain boundaries in YBa2Cu3O7−δ have been found to exhibit anomalously good superconducting critical currents, associated with magnetic flux pinning, although no special interfacial structure has heretofore been associated with this misorientation. We present an analysis of the geometry of the grain boundary in question and show that it can correspond to a special interface, within the definition of constrained lattice coincidence, which may lead to new understanding of the superconducting behavior of grain boundaries. Our analysis shows that the tetragonal‐to‐orthorhombic phase transformation may have important effects upon grain boundary structure and properties, indicating new approaches to producing …

Doping And Pressure Studies On Ybbipt, A. Lacerda, R. Movshovich, M. F. Hundley, Paul C. Canfield, D. Arms, G. Sparn, J. D. Thompson, Z. Fisk, N. E. Philips, H.-R. Ott

Paul C. Canfield

The compound YbBiPt exhibits an extremely large low‐temperature C/T (γ∼8 J K−2 mol−1/Yb) which, if due solely to a renormalized effective mass, would make this material the heaviest correlated electron system known to date. In the Kondo model, the very large γ corresponds to a small characteristic energy scale that is expected to be pressure dependent. We have studied the effect of chemical pressure on YbBiPt single crystals by heat‐capacity measurements on Y and Lu‐doped samples. We have also made preliminary low‐temperature measurements under hydrostatic pressure of the heat capacity (300 mK≤T≤2 K, up to 8 kbar) and resistance (30 …

Nqr Study Of Local Structure And Cooling Rate‐Dependent Superconductivity In La2cuo4+Δ, A. P. Reyes, E. T. Ahrens, P. C. Hammel, J. D. Thompson, Paul C. Canfield, Z. Fisk, R. H. Heffner, J. E. Schirber

Paul C. Canfield

Preliminary results of structural studies in oxygen‐annealed La2CuO4+δ(δ∼0.03) using 139La nuclear quadrupole resonance (NQR) spectroscopy are reported. Superconducting critical temperatures were found to depend on the rate of cooling through a narrow temperature range near 195 K. Analysis of the 139La NQR spectra reveal that lanthanum atoms in the oxygen‐rich metallic region occupy two sites having different local environments. One site has a structural configuration closely related to the stoichiometric oxygen‐poor compound. The second appears only below 200 K and exhibits a large shift and broad distribution of NQR frequency ν Q . Shifts in ν Q in the vicinity …

A Fast Serial Algorithm For The Finite Temperature Quenched Potts Model, Gregory N. Hassold, Elizabeth A. Holm

Physics Publications

An efficient serial algorithm for finite temperature, quenched Potts model simulations of domain evolution has been developed. This ''n‐fold way'' algorithm eliminates unsuccessful spin flip attempts a priori by flipping sites with a frequency proportional to their site activity, defined as the sum of the probability of success for every possible spin flip at that site. Finite temperature efficiency for high‐spin degeneracy systems is achieved by utilizing a new, analytical expression for the portion of the site activity due to flips to non-neighbor spin values. Hence, to determine the activity of a site, only flips to the …

Quantam Wave Turbulence, Alejandro Garcia, M. Haeri, S. Putterman, P. Roberts

Faculty Publications

The nonlinear quantum kinetic equation for the interaction of sound waves is solved via analytic and numerical techniques. In the classical regime energy cascades to higher frequency (ω) according to the steady-state power law ω-3/2. In the quantum limit, the system prefers a reverse cascade of energy which follows the power law ω-6. Above a critical flux, a new type of spectrum appears which is neither self-similar nor close to equilibrium. This state of nonlinear quantum wave turbulence represents a flow of energy directly from the classical source to the quantum degrees of freedom.

Contributions Of The Low-Latitude Boundary Layer To The Finite Width Magnetotail Convection Model, Harlan E. Spence, M. G. Kivelson

Physics & Astronomy

Convection of plasma within the terrestrial nightside plasma sheet contributes to the structure and, possibly, the dynamical evolution of the magnetotail. In order to characterize the steady state convection process, we have extended the finite tail width model of magnetotail plasma sheet convection. The model assumes uniform plasma sources and accounts for both the duskward gradient/curvature drift and the earthward E × B drift of ions in a two-dimensional magnetic geometry. During periods of slow convection (i.e., when the cross-tail electric potential energy is small relative to the source plasma's thermal energy), there is a significant net duskward displacement of …

Mass And Mixing-Angle Patterns In The Standard Model And Its Minimal Supersymmetric Extension, H. Arason, Diego Castano, E. J. Piard, P. Ramond

Chemistry and Physics Faculty Articles

Using renormalization group techniques, we examine several interesting relations among masses and mixing angles of quarks and leptons in the standard model. We extend the analysis to the minimal supersymmetric extension to determine its effect on these mass relations. Remarkably supersymmetry allows for these relations to be satisfied at a single grand unified scale.

Selective Excitation Via The Continuum And Suppression Of Ionization, C. E. Carroll, Foek T. Hioe

Physics Faculty/Staff Publications

Two laser pulses that overlap in time have been successfully used for coherent excitation of a molecule or atom to a desired state. An intermediate state that is at or near resonance with the laser frequencies has been used in past experiments and calculations. Here we replace this intermediate state by a continuum of intermediate states. An analytic solution of a simple model suggests that the continuum can be used in such an excitation scheme, provided that the laser pulses are arranged in the so-called counter intuitive order. %'e use a special case of this solution to relate this work …

The Production And Escape Of Nitrogen Atoms On Mars, Jane L. Fox

Physics Faculty Publications

We have computed the production rates and densities of odd nitrogen species in the Martian atmosphere using updated rate coefficients and a revised ionosphere-thermosphere model. We find that the computed densities of NO are somewhat smaller than those measured by Viking 1, but reasonable agreement can be obtained by assuming that the rate coefficient for loss of odd nitrogen in the reaction of N with NO is smaller at temperatures that prevail in the lower Martian thermosphere (about 130–160 K) than the standard value, which applies to temperatures of 200–400 K. We have also modeled the escape fluxes of N …

Quantam Wave Turbulence, Alejandro Garcia, M. Haeri, S. Putterman, P. Roberts

Alejandro Garcia

The nonlinear quantum kinetic equation for the interaction of sound waves is solved via analytic and numerical techniques. In the classical regime energy cascades to higher frequency (ω) according to the steady-state power law ω-3/2. In the quantum limit, the system prefers a reverse cascade of energy which follows the power law ω-6. Above a critical flux, a new type of spectrum appears which is neither self-similar nor close to equilibrium. This state of nonlinear quantum wave turbulence represents a flow of energy directly from the classical source to the quantum degrees of freedom.

Multimedia - Hype Or No?, Robert Fuller

Robert G. Fuller Publications

Commonly, multimedia is used as a modern name for interactive video. It simply means using a computer to control the presentation of video images to an audience. It facilitates glitzy presentations of boring data. In my view, this is hype.

However, there is a more profound sense of the term. Multimedia can be seen in an historical context that places it in the tradition that began with Vannevar Bush, director of the U.S. Office of Scientific Research and Development, who in 1945 published an article, "As We May Think" in the Atlantic Monthly. In that article he suggested a "future …

Erratum: "Temperature And Suction Effects On The Instability Of An Infinite Swept Attachment Line" [Physics Of Fluids A 4, 2008 (1992)], D. G. Lasseigne, T. L. Jackson, F. Q. Hu

Mathematics & Statistics Faculty Publications

Erratum to:

Lasseigne, D. G., Jackson, T. L., & Hu, F. Q. (1992). Temperature and suction effects on the instability of an infinite swept attachment line. Physics of Fluids A: Fluid Dynamics, 4(9), 2008-2012. doi:10.1063/1.858370

Trapping-To-Percolation Transition In The Hopping Diffusion Of Substitutionally Disordered Solids With A Binary Energy Distribution, Paul Ernest Parris, B. D. Bookout

Physics Faculty Research & Creative Works

We consider charge carriers that undergo nearest-neighbor hopping among the sites of a binary random lattice, each site of which is associated with one of two possible energies E₁ or E₂. A general and recently observed feature of this problem not predicted by previous treatments of disordered hopping models is a crossover between trap-limited conduction and percolation. We introduce new energy-projected equations of motion whose solutions reveal the deep conductivity minimum associated with this phenomenon, and compare the results predicted to numerical simulations.

The Light Ion Lmf And Its Relevance To Ife, Ronald E. Olson, G. O. Allshouse, D. L. Cook, T. R. Lockner, M. G. Mazarakis, C. L. Olson, D. L. Smith

Physics Faculty Research & Creative Works

The inertial confinement fusion (ICF) program at Sandia National Laboratories (SNL) is directed toward validating light ions as an efficient driver for ICF defense and energy applications. The light ion laboratory microfusion facility (LMF) is envisioned as a facility in which high gain ICF targets could be developed and utilized in defense-related experiments. The relevance of LMF technology to eventual inertial fusion energy (IFE) applications is assessed via a comparison of LMF technologies with those projected in the Light Ion Beam Reactor Assessment (LIBRA) conceptual reactor design study

The Lmf Triaxial Mitl Voltage Adder System, Ronald E. Olson, M. G. Mazarakis, D. L. Smith, L. F. Bennett, T. R. Lockner, J. W. Poukey

Physics Faculty Research & Creative Works

No abstract provided.

Defect Structure Of Y1-Ycaymno3 And La1-Ycaymno3. Ii. Oxidation-Reduction Behavior, J. W. Stevenson, M. M. Nasrallah, Harlan U. Anderson, Don M. Sparlin

Materials Science and Engineering Faculty Research & Creative Works

Electrical conductivity, Seebeck coefficient, and thermogravimetric behavior of compositions in the systems Y_1-yCa_yMnO₃ and Y_1-yCa_yMnO₃ were studied as functions of temperature and ambient oxygen activity in order to determine the mechanism of electrical transport and defect structure. Compositions in Y_1-yCa_yMnO₃ exhibited very slight oxygen activity-dependent behavior as the ambient oxygen activity was reduced. A defect model which includes the thermally excited disproportionation of Mn³⁺ into Mn²⁺ and Mn⁴⁺ pairs was applied to the oxygen-activity-dependent data for La_0.80Ca_0.20MnO_{3 …}

The Light-Ion Pulsed Power Induction Accelerator For The Laboratory Microfusion Facility (Lmf), Ronald E. Olson, J. Boyes, M. G. Mazarakis, D. L. Smith, L. F. Bennett, T. R. Lockner, J. W. Poukey

Physics Faculty Research & Creative Works

In order to initiate ignition and substantial energy yield from an inertial confinement fusion target (ICF), a light-ion pulse of ~700 TW peak power and 15-20 ns duration is required. The preconceptual design presented provides this power. The HERMES-III technology of linear inductive voltage addition in a self-magnetically insulated transmission line (MITL) is utilized to generate the 25-36 MV peak voltage needed for lithium ion beams. The 15-20 MA ion current is achieved by utilizing many accelerating modules in parallel. The lithium ion beams are produced in two-stage extraction diodes. To provide the two separate voltage pulses required by the …

Electric-Field Stabilization And Competition Of Gratings In A Photorefractive Polymer, Stephen Ducharme, Brian Jones, James M. Takacs, Lei Zhang

Stephen Ducharme Publications

We report observations of electric-field stabilization of gratings and grating competition in a new photorefractive polymer mixture composed of 40 wt. % diethylamino-benzaldehyde-diphenyl hydrazone dissolved in Bisphenol A 4,4'-nitroaminotolane. Gratings formed with a 650-nm optical wavelength in 145-μm-thick films at 138-kV/cm bias field have a diffraction efficiency as high as 0.11%, require an energy density of –1 J/cm² for formation, and show cancellation, revelation, and electric-field-stabilized persistence. We propose a model in which fast recording is associated with one set of photosensitive traps, whereas a slower cancellation and subsequent revelation are associated with a competing grating formed …

Light-Scattering Technique For The Study Of Dynamic Thickness Fluctuations In Thin Liquid Films, Richard C. Haskell, Daniel C. Petersen, Mark W. Johnson

All HMC Faculty Publications and Research

The authors describe a light-scattering technique capable of probing the dynamics of thickness fluctuations in lipid bilayers. The technique, which they call reflectance fluctuation spectroscopy (RFS), is keenly sensitive to light scattered from the squeeze modes of motion in a thin liquid film, and insensitive to light scattered from the bend modes. A laser beam is focused to a small spot on the film, and the power in the specularly reflected beam is recorded in real time. Thickness fluctuations associated with the squeeze modes of motion give rise to fluctuations in the power of the specularly reflected light. The frequency …