Physical Sciences and Mathematics Commons^™

Smartlabs Provides Hands-On Physics Experience, Erin Heldstab

Lake Union Herald

No abstract provided.

Lorentz-Violating Electromagnetostatics, Quentin G. Bailey

Publications

In this talk, the stationary limit of Lorentz-violating electrodynamics is discussed. As illustrated by some simple examples, the general solution includes unconventional mixing of electrostatic and magnetostatic effects. I discuss a high-sensitivity null-type measurement, exploiting Lorentz-violating electromagnetostatic effects, that could improve existing limits on parity-odd coefficients for Lorentz violation in the photon sector.

Spectroscopy Using Short-Path Surface Plasmon Dispersion, Philip Ryan Boudreaux

Masters Theses

A miniature surface-plasmon based spectrometer is presented for both the near zone and the far zone. In the near zone four different experiments have been completed with this system. It will be shown that with 632, 614, 543, and 440 nm incident lasers upon the system there is good agreement between experimental and theoretical transmission spectra. This system is shown to provide transmission spectra of different broad band-pass, glass filters across the visible wavelength range with high stray-light rejection at low resolution. These spectra are compared to those taken with a commercial spectrophotometer. Spectra of solutions of the laser dye …

Measurement Of Charge Storage Decay Time And Resistivity Of Spacecraft Insulators, Prasanna V. Swaminathan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Insulators used in the construction of spacecraft are irradiated with high-energy electrons in the space environment and this sometimes causes the insulators to charge to very high voltages. Such charged insulators can generate spontaneous electric partial-discharge pulses of the order of mA to tens of A. These pulses sometimes last enough time to destroy the expensive micro-circuitry present in the spacecraft. In evaluating the threat to the spacecraft due to these discharges, calculation of the resistivity becomes a critical parameter since it determines how accumulated charge will distribute across the spacecraft and how rapidly charge imbalance will dissipate. So far, …

Circular Dichroism At Equal Energy Sharing In Photo-Double-Ionization Of He, Andrei Y. Istomin, N. L. Manakov, A. V. Meremianin, Anthony F. Starace

Department of Physics and Astronomy: Faculty Publications

Interference between dipole and quadrupole transition amplitudes in photo-double-ionization of He by an elliptically polarized vuv photon is shown to induce circular dichroism in the case of equal energy sharing. The magnitude of this retardation-induced dichroic effect is estimated and its impact on the nondipole asymmetries of the triply differential cross section is demonstrated.

Planetary Waves And Tides Found Using Lomb-Scargle Periodogram Analysis Of Rayleigh-Scatter Data Above Utah State University, Karen L. Nelson, Joshua P. Herron, Vincent B. Wickwar

Posters

Because of the significant gaps in nighttime-only data, traditional Fourier techniques are difficult to use to identify tides and short-period planetary waves (PWs). The Lomb-Scargle per- iodogram is a method that was developed by as- tronomers to identify oscillations in nighttime-only and otherwise incomplete data. For the same rea- sons, it is also a powerful tool for aeronomers. The Lomb-Scargle technique is described with particular emphasis on its application to nighttime- only lidar data. Because of the gaps in the data, attention is also placed on techniques used to identify aliasing in the Lomb-Scargle periodo- grams. The method is applied …

Qvd Sensors As Focal Plane Instruments For X-Ray Timing Applications, Kent S. Wood, Armen Gulian, Paul S. Ray

Mathematics, Physics, and Computer Science Faculty Articles and Research

“QVD” detectors are based on thermoelectric heat‐to‐voltage (Q→V) conversion and digital (V→D) readout. For spectroscopic applications, the theoretical performance limits are competitive with superconducting tunnel junction (STJ) detectors and transition edge sensor (TES) devices. We discuss theoretical and demonstrated timing performance of QVD detectors with different design architectures. Detectors with lanthanum‐cerium hexaboride sensors can be very fast, up to 100 MHz/pixel counting rates. They can serve as focal plane detectors for X‐ray timing, in situations where very large apertures are used to gather X‐ray photons at high event rates. Practical implementation of thermoelectric (QVD) detectors requires cryogenic thermoelectric sensors with …

Reactor Physics Studies For The Afci Race Project: Reactor-Accelerator Coupling Experiments Project, Denis Beller

Transmutation Sciences Physics (TRP)

In the RACE Project of the U.S. Advanced Fuel Cycle Initiative (AFCI), a series of accelerator driven subcritical systems (ADSS) experiments will be conducted at the Idaho State University’s Idaho Accelerator Center (ISU-IAC), at the University of Texas (UT) at Austin, and at the Texas A&M University. In these experiments we will use electron accelerators to induce bremsstrahlung photon-neutron reactions in heavy-metal targets; this source of about 10¹² to 10¹³ n/s will then initiate fission reactions in the subcritical systems. These systems will include a compact, transportable assembly at ISU and TRIGA reactors at UT-Austin and Texas A&M. …

Training Of The Exchange-Bias Effect: A Simple Analytic Approach, Christian Binek

Christian Binek Publications

raining of the exchange bias effect in antiferro-/ferromagnetic heterostructures is considered in the theoretical framework of spin configurational relaxation, which is activated through consecutively cycled hysteresis loops. The corresponding exchange bias fields, µ₀ H_EB(n), reveal relaxation from the initial state, n = 1, of high antiferromagnetic interface magnetization to the equilibrium state of reduced magnetization in the limit of large n. The evolution of µ₀H_EB vs n is calculated with the help of a discretized Landau-Khalatnikov equation, where the continuous time parameter is replaced by the loop index n. The result reveals the origin …

Hong-Ou-Mandel Cloning: Quantum Copying Without An Ancilla, Irfan Ali Khan, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

In this paper we report an experimental realization of an ancilla-free 1→2 phase-covariant quantum cloner. The cloner is realized by interfering a linearly polarized photon, which we wish to clone with a circularly polarized photon at a beam splitter. The two-photon effect can be understood in light of Hong-Ou-Mandel interference. The fidelity of the cloner was measured as 0.829±0.008 for the 0∕90 basis and 0.835±0.006 for the 45∕135 basis, which is in good agreement with the theoretical prediction of 5∕6 fidelity. The experimental scheme is straightforward and has a high cloning success rate.

Search For BS0 Μ+Μ- And BD0 Μ+Μ- Decays In Pp̅ Collisions At √S =1.96 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report on a search for B_s⁰→ µ⁺µ^- and B_d⁰→ µ⁺µ^- decays in p collisions at =1.96 TeV using 171 pb–1 of data collected by the CDF II experiment at the Fermilab Tevatron Collider. The decay rates of these rare processes are sensitive to contributions from physics beyond the standard model. One event survives all our selection requirements, consistent with the background expectation. We derive branching ratio limits of Ɓ (B_s⁰→µ⁺µ^-)B_d⁰→µ+µ–)<1.5×10^-7 at 90% confidence level.

Mean-Field Theory Of Collective Transport With Phase Slips, Karl Saunders, J. M. Schwarz, M. Christina Marchetti, A. Alan Middleton

Physics

The driven transport of plastic systems in various disordered backgrounds is studied within mean field theory. Plasticity is modeled using nonconvex interparticle potentials that allow for phase slips. This theory most naturally describes sliding charge density waves; other applications include flow of colloidal particles or driven magnetic flux vortices in disordered backgrounds. The phase diagrams exhibit generic phases and phase boundaries, though the shapes of the phase boundaries depend on the shape of the disorder potential. The phases are distinguished by their velocity and coherence: the moving phase generically has finite coherence, while pinned states can be coherent or incoherent. …

On The Variability Of The Fine Structure Constant, Jason Lott Evans

Theses and Dissertations

This thesis addresses the issue of the time variability of the fine structure constant, alpha. Recent claims of a varying alpha are set against the established standards of quantum electrodynamical theory and experiments. A study of the feasibility of extracting data on the time dependence of alpha using particles in Penning traps is compared to the results obtained by existing methods, including those using astrophysical data and those obtained in atomic clock experiments. Suggestions are made on the nature of trapped particles and the trapping fields.

Search For Pair Production Of Light Scalar Top Quarks In Pp̅ Collisions At √S = 1.8 Tev, V. M. Abazov, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

Using 85.2 ± 3.6 pb¹ of pp̅ collisions collected at √s = 1.8 TeV with the D0 detector at Fermilab’s Tevatron Collider, we present the results of a search for direct pair production of scalar top quarks (t̃), the supersymmetric partners of the top quark. We examined events containing two or more jets and missing transverse energy, the signature of light scalar top quark decays to charm quarks and neutralinos. After selections, we observe 27 events while expecting 31.1 ± 6.4 events from known standard model processes. Comparing these results to next-to-leading-order production cross sections, we …

Comparisons Of Long-Term Trends And Variability In The Middle Atmosphere, Troy Wynn, Joshua P. Herron, Vincent B. Wickwar

Posters

Rayleigh Lidar is routinely used to measure temperatures in the middle atmosphere from 45 to 90 km. It is well adapted for nightly observation, provides excellent vertical temperature resolution, and does not need external calibration. The USU Rayleigh Lidar (41.74°N 111.81°W) dataset spans more than ten years from September 1993 to July 2003 with 62 monthly profiles (about 5 years of data) spread over that period.

With many sources of variation in the atmosphere, all temperature effects cannot be detected. The largest source, and the easiest to measure, is the seasonal variation. In addition there are semiannual variation, secular trends, …

Mutually Unbiased Bases And Trinary Operator Sets For N Qutrits, Jay Lawrence

Dartmouth Scholarship

A complete orthonormal basis of N-qutrit unitary operators drawn from the Pauli Group consists of the identity and 9^N-1 traceless operators. The traceless ones partition into 3^N+1 maximally commuting subsets (MCS's) of 3^N-1 operators each, whose joint eigenbases are mutually unbiased. We prove that Pauli factor groups of order 3^N are isomorphic to all MCS's, and show how this result applies in specific cases. For two qutrits, the 80 traceless operators partition into 10 MCS's. We prove that 4 of the corresponding basis sets must be separable, while 6 must be totally entangled (and Bell-like). For three qutrits, 728 operators …

National Academy Of Sciences Study On The Comprehensive Nuclear Test Ban Treaty, David W. Hafemeister

Physics

No abstract provided.

Modelling Stochastic Gene Expression, Olienka Patricia Fernandez

Graduate Student Papers (Physics)

No abstract provided.

Physical Conditions In Orion's Veil, N. P. Abel, C. L. Brogan, Gary J. Ferland, C. R. O'Dell, G. Shaw, Thomas H. Troland

Physics and Astronomy Faculty Publications

Orion's veil consists of several layers of largely neutral gas lying between us and the main ionizing stars of the Orion Nebula. It is visible in 21 cm H I absorption and in optical and UV absorption lines of H I and other species. Toward θ¹ Ori C, the veil has two remarkable properties, a high magnetic field (~100 μG) and a surprising lack of H₂, given its total column density. Here we compute photoionization models of the veil to establish its gas density and its distance from θ¹ Ori C. We use a greatly improved …

Optical Variability Of Narrow-Line Seyfert 1 Galaxies, Elizabeth S. Klimek, C. Martin Gaskell, Cecilia H. Hedrick

Department of Physics and Astronomy: Faculty Publications

We present results of a broadband photometric study of the optical variability of six narrow-line Seyfert 1 (NLS1) galaxies observed at 172 epochs. We searched for microvariability on 33 nights. Strong evidence for microvariability was found only for our lowest luminosity object, NGC 4051, on one night. Weaker evidence suggests such variability on a few other nights for two other objects, but the data are not as convincing. Intranight variability in NLS1’s is thus concluded to be rare and of low amplitude. We give illustrations of how variable image quality can produce spurious variability. We find that for well-studied non-NLS1’s …

Focused Ion Beam Milled Copt Magnetic Force Microscopy Tips For High Resolution Domain Images, L. Gao, Lanping Yue, T. Yokota, Ralph Skomski, Sy-Hwang Liou, H. Takahoshi, Hitoshi Saito, S. Ishio

Department of Physics and Astronomy: Faculty Publications

Abstract—High-coercivity CoPt magnetic force microscope tips have been modified by focused ion beam milling to improve the resolution of magnetic domain images. The magnetic materials around the apex have been removed, leaving a 30-nm diameter magnetic particle at the tip end. Due to the smaller amount of magnetic material, the stray field from this new tip is significantly reduced, and the spatial resolution of the magnetic domain images is improved. The tip is used to obtain high-resolution domain images of a CoCrPt-SiO2/Ru perpendicular recording medium with linear recording densities from 800 to 1000 kfci. Magnetic patterns of 900 kfci, corresponding …

L10 Ordered Fept:C Composite Films With (001) Texture, M. L. Yan, Renat F. Sabirianov, Y. F. Xu, X Z. Li, David J. Sellmyer

Physics Faculty Publications

Highly textured (001) FePt:C nanocomposite thin films, deposited directly on thermally oxidized Si wafers, are obtained by multilayer deposition plus subsequent thermal annealing. Nanostructures, crystalline orientations, interactions, and magnetic properties are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), magnetic force microscopy, and magnetic measurements. The formation of the ordered L1₀ phase is confirmed by XRD, and only visible (00 ) peaks indicate a high degree of the (001) texture. TEM observation reveals that FePt grains are embedded in the C matrix and appear to be well isolated.

Micromagnetic Domain Structures In Cylindrical Nickel Dots, George D. Skidmore, Andrew Kunz, C. E. Campbell, E. Dan Dahlberg

Physics Faculty Research and Publications

The magnetic domain structures of cylindrical nickel dots (diameters from 40 nm to 1700 nm) with anisotropy parallel to the cylinder axis is predicted by the ratio of the dot diameter to the stripe period of unpatterned films with the same perpendicular anisotropy. The dominant domain structure for a given ratio increases in complexity as the ratio increases. We present evidence for the full micromagnetic domain structure for the simplest cases.

Spectroscopic And Microscopic Investigation Of The Corrosion Of 316/316l Stainless Steel By Lead-Bismuth Eutectic (Lbe) At Elevated Temperatures: Importance Of Surface Preparation, Allen L. Johnson, Denise Parsons, Julia Manzerova, Dale L. Perry, Daniel Koury, Brian D. Hosterman, John Farley

Transmutation Sciences Materials (TRP)

The corrosion of steel by lead–bismuth eutectic (LBE) is an important issue in proposed nuclear transmutation schemes. Russian scientists at the IPPE exposed steel samples to oxygen-controlled LBE at temperatures up to 823 K and exposure times up to 3000 h. We have characterized these post-exposure steel samples and unexposed controls, using scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDAX) and X-ray photoelectron spectroscopy (XPS). Previous researchers have investigated the corrosion by LBE of steel of varying composition. In the present work, we compared two samples having the same composition (standard nuclear grade 316/316L) but different surface preparation: a cold-rolled …

Thunderstorm And Lightning Characteristics Associated With Sprites In Brazil, O. Pinto Jr., M. M.F. Saba, I. R.C.A. Pinto, F. S.S. Tavares, K. P. Naccarato, N. N. Solorzano, Michael J. Taylor, P. D. Pautet, R. H. Holzworth

All Physics Faculty Publications

A study of the thunderstorm and cloud-ground lightning characteristics associated with sprite events observed in Brazil is presented. The study is based on ground and aircraft sprite observations with high sensitivity intensified CCD cameras of six different thunderstorms, GOES satellite infrared images, radar and lightning network data. A total of eighteen transient optical events were recorded at three different days in 2002 and 2003, sixteen of which exhibited vertical structures typically associated with sprites. Four thunderstorms were associated with two different cold fronts, one with a Mesoscale Convective System, and one was a local isolated thunderstorm. The sprites occurred during …

Electronic Structure And Light-Induced Conductivity Of A Transparent Refractory Oxide, Julia E. Medvedeva, Arthur J. Freeman, Mariana I. Bertoni, Thomas O. Mason

Physics Faculty Research & Creative Works

Combined first-principles and experimental investigations reveal the underlying mechanism responsible for a drastic change of the conductivity (by 10 orders of magnitude) following hydrogen annealing and UV irradiation in a transparent oxide, 12CaO · 7Al₂O₃, found by Hayashi et al. [Nature (London) 419, 462 (2002).] The charge transport associated with photoexcitation of an electron from H^- occurs by electron hopping.We identify the atoms participating in the hops, determine the exact paths for the carrier migration, estimate the temperature behavior of the hopping transport, and predict a way to enhance the conductivity by specific doping.

Charge Transfer In Slow Collisions Of O⁸⁺ And Ar⁸⁺ Ions With H(1s) Below 2 Kev/Amu, Teck-Ghee Lee, M. Hesse, Anh-Thu Le, C. D. Lin

Physics Faculty Research & Creative Works

We calculated the charge-transfer cross sections for O⁸⁺ + H collisions for energies from 1eV/amu to 2keV/amu, using the recently developed hyperspherical close-coupling method. In particular, the discrepancy for electron capture to the n = 6 states of O⁷⁺ from the previous theoretical calculations is further analyzed. Our results indicate that at low energies (below 100eV∕amu) electron capture to the n=6 manifold of O7+ becomes dominant. The present results are used to resolve the long-standing discrepancies from the different elaborate semiclassical calculations near 100eV/amu. We have also performed the semiclassical atomic orbital close-coupling calculations with straight-line trajectories. We found the …

Evidence For A Narrow Baryonic State Decaying To KS0P And KS0P̄ In Deep Inelastic Scattering At Hera, S. Chekanov, M. Derrick, J. H. Loizides, S. Magill, S. Miglioranzi, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, A. Montanari, R. Nania, F. Palmonari, A. Pesci, L. Rinaldi

Faculty Publications

A resonance search has been made in the K0Sp and K0Sp̄ invariant-mass spectrum measured with the ZEUS detector at HERA using an integrated luminosity of 121 pb-1. The search was performed in the central rapidity region of inclusive deep inelastic scattering at an ep centre-of-mass energy of 300-318 GeV for exchanged photon virtuality, Q2, above 1 GeV2. Recent results from fixed-target experiments give evidence for a narrow baryon resonance decaying to K+n and K0Sp, interpreted as a pentaquark. The results presented here support the existence of such state, with a mass of 1521.5±1.5(stat.)+2.8-1.7(syst.) MeV and a Gaussian width consistent with …

Excitation Energies From Time-Dependent Density-Functional Theory Beyond The Adiabatic Approximation, Carsten A. Ullrich, Kieron Burke

Physics Faculty Research & Creative Works

The nonadiabatic effects for excitation energies from time-dependent density-functional theory (TDDFT) were analyzed. a general analytic expression for nonadiabatic corrections to excitation energies of finite systems was derived and singlet s→s and s→p excitations of closed-shell atoms were calculated. It is observed that as the Vignale, Ullrich and Conti (VUC) functional is based on frequency-dependent xc kernel of homogeneous electron gas so it produces excitation energies with small but finite imaginary parts. the results show that the VUC approach determines excitation energies for atomic and molecular systems as well as for plasmon-like excitations in solids.

Hysteresis Of Granular Fept:Ag Films With Perpendicular Anisotropy, M. L. Yan, Ralph Skomski, Arti Kashyap, L. Gao, Sy-Hwang Liou, David J. Sellmyer

Department of Physics and Astronomy: Faculty Publications

Intergranular interactions in nanostructured FePt:Ag thin films and their effect on magnetic hysteresis are investigated. The films, produced by multilayer deposition plus rapid thermal annealing, consist of FePt nanoparticles embedded in a silver matrix. They are investigated by magnetization measurements and magnetic force microscopy. Analytical model calculations, supported by micromagnetic simulations, are used to elucidate the relation between coercivity, hysteresis-loop slope, and spatial correlations during magnetization reversal. The analytical calculations yield simple expressions for the loop slope and the coercivity as a function of the intergranular exchange. Small intergranular exchange enhances the coercivity, but for strong exchange there is a …