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2014

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Articles 1 - 30 of 1822

Full-Text Articles in Physics

Mueller Matrix Spectroscopic Ellipsometry Of Multiferroics, Roman Basistyy Dec 2014

Mueller Matrix Spectroscopic Ellipsometry Of Multiferroics, Roman Basistyy

Dissertations

Multiferroics, materials which possess several ferroic orders, are the focus of research in recent years. Among these materials are oxide crystals, such as, for example, RMnO3, RMn2O5, R3Fe5O12, where R stands for rare earth ions. The most fascinating physics occurs when magnon-lattice coupling reveals itself in the far-IR spectra of multiferroics. The expected optical behavior puts multiferroics into a more general category of bi-anisotropic materials, the properties of which could be only described using anisotropic dielectric ε(ω), magnetic μ(ω), and magnetoelectric α(ω), α'(ω) tensors. In ...


Electronic, Thermoelectric And Optical Properties Of Vanadium Oxides: Vo2, V2o3 And V2o5, Chiranjivi Lamsal Dec 2014

Electronic, Thermoelectric And Optical Properties Of Vanadium Oxides: Vo2, V2o3 And V2o5, Chiranjivi Lamsal

Dissertations

Correlated electrons in vanadium oxides are responsible for their extreme sensitivity to external stimuli such as pressure, temperature or doping. As a result, several vanadium oxides undergo insulator-to-metal phase transition (IMT) accompanied by structural change. Unlike vanadium pentoxide (V3O3), vanadium dioxide (VO3) and vanadium sesquioxide (V3O3) show I MT in their bulk phases. In this study, we have performed one electron Kohn-Sham electronic band-structure calculations of VO3, V3O3 and V2O5 in both metallic and insulating phases, implementing a full ab-initio simulation package based on Density Functional ...


A Comprehensive Study Of Evolution Of Photospheric Magnetic Field And Flows Associated With Solar Eruptions, Shuo Wang Dec 2014

A Comprehensive Study Of Evolution Of Photospheric Magnetic Field And Flows Associated With Solar Eruptions, Shuo Wang

Dissertations

The rapid, irreversible change of the photospheric magnetic field has been recognized as an important element of the solar flare process. Recent theoretical work has shown that such a change would imply Lorentz force perturbations acting on both the outer solar atmosphere and the solar surface. This research uses vector magnetograms obtained with the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory to study a number of flares, which range from GOES-class C4 to X5 and occur in four active regions. In all the events, a permanent and rapid change of photospheric magnetic field closely associated with the ...


Statistics Of The Island-Around-Island Hierarchy In Hamiltonian Phase Space, Or Alus, Shmuel Fishman, James Meiss Dec 2014

Statistics Of The Island-Around-Island Hierarchy In Hamiltonian Phase Space, Or Alus, Shmuel Fishman, James Meiss

Applied Mathematics Faculty Contributions

The phase space of a typical Hamiltonian system contains both chaotic and regular orbits, mixed in a complex, fractal pattern. One oft-studied phenomenon is the algebraic decay of correlations and recurrence time distributions. For area-preserving maps, this has been attributed to the stickiness of boundary circles, which separate chaotic and regular components. Though such dynamics has been extensively studied, a full understanding depends on many fine details that typically are beyond experimental and numerical resolution. This calls for a statistical approach, the subject of the present work. We calculate the statistics of the boundary circle winding numbers, contrasting the distribution ...


Measurement Of Compton Scattering From The Deuteron And An Improved Extraction Of The Neutron Electromagnetic Polarizabilities, L. S. Myers, J. R. M. Annand, J. Brudvik, G. Feldman, H. W. Grießhammer, K. Hansen, S. S. Henshaw, L. Isaksson, R. Jebali, Michael A. Kovash, M. Lundin, J. A. Mcgovern, D. G. Middleton, A. M. Nathan, D. R. Phillips, B. Schröder, S. C. Stave Dec 2014

Measurement Of Compton Scattering From The Deuteron And An Improved Extraction Of The Neutron Electromagnetic Polarizabilities, L. S. Myers, J. R. M. Annand, J. Brudvik, G. Feldman, H. W. Grießhammer, K. Hansen, S. S. Henshaw, L. Isaksson, R. Jebali, Michael A. Kovash, M. Lundin, J. A. Mcgovern, D. G. Middleton, A. M. Nathan, D. R. Phillips, B. Schröder, S. C. Stave

Physics and Astronomy Faculty Publications

The electromagnetic polarizabilities of the nucleon are fundamental properties that describe its response to external electric and magnetic fields. They can be extracted from Compton-scattering data—and have been, with good accuracy, in the case of the proton. In contradistinction, information for the neutron requires the use of Compton scattering from nuclear targets. Here, we report a new measurement of elastic photon scattering from deuterium using quasimonoenergetic tagged photons at the MAX IV Laboratory in Lund, Sweden. These first new data in more than a decade effectively double the world data set. Their energy range overlaps with previous experiments and ...


Gauge Transformations Of The Biconformal Connection, James Thomas Wheeler Dec 2014

Gauge Transformations Of The Biconformal Connection, James Thomas Wheeler

All Physics Faculty Publications

We study the changes of the biconformal gauge fields under the local rotational and dilatational gauge transformations.


Inductive Measurement Of Optically Hyperpolarized Phosphorous Donor Nuclei In An Isotopically Enriched Silicon-28 Crystal, P. Gumann, O. Patange, C. Ramanathan, H. Haas Dec 2014

Inductive Measurement Of Optically Hyperpolarized Phosphorous Donor Nuclei In An Isotopically Enriched Silicon-28 Crystal, P. Gumann, O. Patange, C. Ramanathan, H. Haas

Open Dartmouth: Faculty Open Access Scholarship

We experimentally demonstrate the first inductive readout of optically hyperpolarized phosphorus-31 donor nuclear spins in an isotopically enriched silicon-28 crystal. The concentration of phosphorus donors in the crystal was 1.5×1015  cm−3, 3 orders of magnitude lower than has previously been detected via direct inductive detection. The signal-to-noise ratio measured in a single free induction decay from a 1  cm3 sample (≈1015 spins) was 113. By transferring the sample to an X-band ESR spectrometer, we were able to obtain a lower bound for the nuclear spin polarization at 1.7 K of ∼64%. The 31P-T2 measured with a ...


Investigation Of Emic Wave Scattering As The Cause For The Barrel 17 January 2013 Relativistic Electron Precipitation Event: A Quantitative Comparison Of Simulation With Observations, Zan Li, Robyn M. Millan, Mary K. Hudson, Leslie A. Woodger, David M. Smith, Yue Chen, R. Friedel, J. V. Rodriguez, Mark J. Engebretson, J. Goldstein, Joseph F. Fennell, Harlan E. Spence Dec 2014

Investigation Of Emic Wave Scattering As The Cause For The Barrel 17 January 2013 Relativistic Electron Precipitation Event: A Quantitative Comparison Of Simulation With Observations, Zan Li, Robyn M. Millan, Mary K. Hudson, Leslie A. Woodger, David M. Smith, Yue Chen, R. Friedel, J. V. Rodriguez, Mark J. Engebretson, J. Goldstein, Joseph F. Fennell, Harlan E. Spence

Physics Scholarship

Abstract

Electromagnetic ion cyclotron (EMIC) waves were observed at multiple observatory locations for several hours on 17 January 2013. During the wave activity period, a duskside relativistic electron precipitation (REP) event was observed by one of the Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) balloons and was magnetically mapped close to Geostationary Operational Environmental Satellite (GOES) 13. We simulate the relativistic electron pitch angle diffusion caused by gyroresonant interactions with EMIC waves using wave and particle data measured by multiple instruments on board GOES 13 and the Van Allen Probes. We show that the count rate, the energy ...


Potential Energy Curves And Associated Line Shape Of Alkali-Metal And Noble-Gas Interactions, Larry A. Blank Dec 2014

Potential Energy Curves And Associated Line Shape Of Alkali-Metal And Noble-Gas Interactions, Larry A. Blank

Theses and Dissertations

Recent interest in optically-pumped alkali laser systems has prompted this study into the binary interaction potentials between species of alkali-metal and rare-gas atoms and the effects of the collision of these species on the alkali-metal atom absorption spectrum. Special attention is placed on the relationship of the interaction potentials and the resulting line shape. The X2Σ+1/2, A2π1/2, A2π3/2, and B2Σ+1/2 potential energy curves and associated dipole matrix elements are computed for M+ Ng at the spin-orbit multi-reference configuration interaction level, where M = K, Rb ...


Rainich-Type Conditions For Perfect Fluid Spacetimes, Dionisios Krongos, Charles G. Torre Dec 2014

Rainich-Type Conditions For Perfect Fluid Spacetimes, Dionisios Krongos, Charles G. Torre

Research Vignettes

In this worksheet we describe and illustrate a relatively simple set of new Rainich-type conditions on an n-dimensional spacetime which are necessary and sufficient for it to define a perfect fluid solution of the Einstein field equations. Procedures are provided which implement these Rainich-type conditions and which reconstruct the perfect fluid from the metric. These results provide an example of the idea of geometrization of matter fields in general relativity, which is a purely geometrical characterization of matter fields via the Einstein field equations.


Shape-Memory Transformations Of Niti: Minimum-Energy Pathways Between Austenite, Martensites, And Kinetically Limited Intermediate States, Nikolai A. Zarkevich, Duane D. Johnson Dec 2014

Shape-Memory Transformations Of Niti: Minimum-Energy Pathways Between Austenite, Martensites, And Kinetically Limited Intermediate States, Nikolai A. Zarkevich, Duane D. Johnson

Ames Laboratory Publications

NiTi is the most used shape-memory alloy; nonetheless, a lack of understanding remains regarding the associated structures and transitions, including their barriers. Using a generalized solid-state nudged elastic band method implemented via density-functional theory, we detail the structural transformations in NiTi relevant to shape memory: those between a body-centered orthorhombic (bco) ground state and a newly identified stable austenite (“glassy” B2-like) structure, including energy barriers (hysteresis) and intermediate structures (observed as a kinetically limited Rphase), and between martensite variants (bco orientations). All results are in good agreement with available experiment. We contrast the austenite results to those from the often-assumed ...


Strain-Driven Growth Of Gaas(111) Quantum Dots With Low Fine Structure Splitting, Paul J. Simmonds Dec 2014

Strain-Driven Growth Of Gaas(111) Quantum Dots With Low Fine Structure Splitting, Paul J. Simmonds

Physics Faculty Publications and Presentations

Symmetric quantum dots (QDs) on (111)-oriented surfaces are promising candidates for generating polarization-entangled photons due to their low excitonic fine structure splitting(FSS). However, (111) QDs are difficult to grow. The conventional use of compressive strain to drive QD self-assembly fails to form 3D nanostructures on (111) surfaces. Instead, we demonstrate that (111) QDs self-assemble under tensile strain by growing GaAs QDs on an InP(111)A substrate. Tensile GaAs self-assembly produces a low density of QDs with a symmetric triangular morphology. Coherent, tensile QDs are observed without dislocations, and the QDs luminescence at room temperature. Single QD measurements ...


Nuclear Structure Aspects Of Neutrinoless Double Beta Decay, B. Alex Brown, Mihai Horoi, Roman A. Sen′Kov Dec 2014

Nuclear Structure Aspects Of Neutrinoless Double Beta Decay, B. Alex Brown, Mihai Horoi, Roman A. Sen′Kov

Publications and Research

We decompose the neutrinoless double-beta decay matrix elements into sums of products over the intermediate nucleus with two less nucleons. We find that the sum is dominated by the J^pi=0^+ ground state of this intermediate nucleus for both the light and heavy neutrino decay processes. This provides a new theoretical tool for comparing and improving nuclear structure models. It also provides the connection to two-nucleon transfer experiments.


Galaxy Zoo: Candels Barred Discs And Bar Fractions, B. D. Simmons, Thomas Melvin, Chris Lintott, Karen L. Masters, Kyle W. Willett, William C. Keel, R. J. Smethurst, Edmond Cheung, Robert C. Nichol, Kevin Schawinski, Michael Rutkowski, Jeyhan S. Kartaltepe, Eric F. Bell, Kevin R. V. Casteels, Christopher J. Conselice, Omar Almaini, Henry C. Ferguson, Lucy Fortson, William Hartley, Dale D. Kocevski, Anton M. Koekemoer, Daniel H. Mcintosh, Alice Mortlock, Jeffrey A. Newman, Jamie Owensworth, Steven Bamford, Tomas Dahlen, Sandra M. Faber, Steven L. Finkelstein, Adriano Fontana, Audrey Galametz, N. A. Grogin, Ruth Grützbauch, Yicheng Guo, Boris Häußler, Kian J. Jek, Sugata Kaviraj, Ray A. Lucas, Michael Peth, Mara Salvato, Tommy Wiklind, Stijn Wuyts Dec 2014

Galaxy Zoo: Candels Barred Discs And Bar Fractions, B. D. Simmons, Thomas Melvin, Chris Lintott, Karen L. Masters, Kyle W. Willett, William C. Keel, R. J. Smethurst, Edmond Cheung, Robert C. Nichol, Kevin Schawinski, Michael Rutkowski, Jeyhan S. Kartaltepe, Eric F. Bell, Kevin R. V. Casteels, Christopher J. Conselice, Omar Almaini, Henry C. Ferguson, Lucy Fortson, William Hartley, Dale D. Kocevski, Anton M. Koekemoer, Daniel H. Mcintosh, Alice Mortlock, Jeffrey A. Newman, Jamie Owensworth, Steven Bamford, Tomas Dahlen, Sandra M. Faber, Steven L. Finkelstein, Adriano Fontana, Audrey Galametz, N. A. Grogin, Ruth Grützbauch, Yicheng Guo, Boris Häußler, Kian J. Jek, Sugata Kaviraj, Ray A. Lucas, Michael Peth, Mara Salvato, Tommy Wiklind, Stijn Wuyts

Physics and Astronomy Faculty Publications

The formation of bars in disc galaxies is a tracer of the dynamical maturity of the population.

The remainder of the abstract is available at:

http://dx.doi.org/10.1093/mnras/stu1817


Identification Of Hyperhalogens In Agn(Bo2)M (N = 1–3, M = 1–2) Clusters: Anion Photoelectron Spectroscopy And Density Functional Calculations, Xiang-Yu Kong, Hong-Guang Xu, Pratik Koirala, Wei-Jun Zheng, Anil K. Kandalam, Puru Jena Dec 2014

Identification Of Hyperhalogens In Agn(Bo2)M (N = 1–3, M = 1–2) Clusters: Anion Photoelectron Spectroscopy And Density Functional Calculations, Xiang-Yu Kong, Hong-Guang Xu, Pratik Koirala, Wei-Jun Zheng, Anil K. Kandalam, Puru Jena

Anil K. Kandalam

No abstract provided.


Hiv-1 Tat Membrane Interactions Probed Using X-Ray And Neutron Scattering, Cd Spectroscopy And Md Simulations., Kiyotaka Akabori, Kun Huang, Bradley Treece, Michael Jablin, Brian Maranville, Arthur Woll, John Nagle, Angel Garcia, Stephanie Tristram-Nagle Dec 2014

Hiv-1 Tat Membrane Interactions Probed Using X-Ray And Neutron Scattering, Cd Spectroscopy And Md Simulations., Kiyotaka Akabori, Kun Huang, Bradley Treece, Michael Jablin, Brian Maranville, Arthur Woll, John Nagle, Angel Garcia, Stephanie Tristram-Nagle

Prof. Stephanie Tristram-Nagle Ph.D.

We report the effect on lipid bilayers of the Tat peptide Y47GRKKRRQRRR57 from the HIV-1 virus transactivator of translation (Tat) protein. Synergistic use of low-angle X-ray scattering (LAXS) and atomistic molecular dynamic simulations (MD) indicate Tat peptide binding to neutral dioleoylphosphocholine (DOPC) lipid headgroups. This binding induced the local lipid phosphate groups to move 3Å closer to the center of the bilayer. Many of the positively charged guanidinium components of the arginines were as close to the center of the bilayer as the locally thinned lipid phosphate groups. LAXS data for DOPC, DOPC/dioleoylphosphoethanolamine (DOPE), DOPC/dioleoylphosphoserine (DOPS), and a ...


What Are The True Values Of The Bending Modulus Of Simple Lipid Bilayers?, John Nagle, Michael Jablin, Stephanie Tristram-Nagle, Kiyotaka Akabori Dec 2014

What Are The True Values Of The Bending Modulus Of Simple Lipid Bilayers?, John Nagle, Michael Jablin, Stephanie Tristram-Nagle, Kiyotaka Akabori

Prof. Stephanie Tristram-Nagle Ph.D.

Values of the bending modulus KC are reviewed, and possible causes for the considerable differences are discussed. One possible cause is the use of glucose and sucrose in the classical micromechanical manipulation and shape analysis methods. New data, using the more recent low angle X-ray method, are presented that do not support an effect of glucose or sucrose on KC. Another possible cause is using an incomplete theory to interpret the data. Adding a tilt term to the theory clearly does not affect the value obtained from the shape analysis method. It is shown that a tilt term, using a ...


Deriving The Dyer-Roeder Equation From The Geodesic Deviation Equation Via The Newman Penrose Null Tetrad, Aly Aly Dec 2014

Deriving The Dyer-Roeder Equation From The Geodesic Deviation Equation Via The Newman Penrose Null Tetrad, Aly Aly

Honors Program Theses and Projects

In this paper we examine the geodesic deviation equation using the Newman-Penrose (N-P) formalism for a flat Friedmann-Lemaitre-Robertson-Walker (FLRW) metric (Carroll, S. (2004); Ryden, B. (2003); Newman & Penrose (1962)). We solved the geodesic deviation equation for angular diameter distance, using the relevant N-P components, and the resulting expression was the Dyer-Roeder equation of cosmology (Ryden, B. (2003)) (Schneider et al. (1992)). This leads us to believe that we can apply the N-P formalism to a perturbed FLRW metric and find a solvable equation for angular diameter distance (Kling & Campbell (2008)). The perturbed FLRW metric incorporates clumps of matter into a ...


Stratified Turbulence In The Nearshore Coastal Ocean: Dynamics And Evolution In The Presence Of Internal Bores, Ryan K. Walter, Michael E. Squibb, C. Brock Woodson, Jeffrey R. Koseff, Stephen G. Monismith Dec 2014

Stratified Turbulence In The Nearshore Coastal Ocean: Dynamics And Evolution In The Presence Of Internal Bores, Ryan K. Walter, Michael E. Squibb, C. Brock Woodson, Jeffrey R. Koseff, Stephen G. Monismith

Physics

High-frequency measurements of stratified turbulence throughout the water column were collected over a 2 week period in the nearshore environment of southern Monterey Bay, CA, using a cabled observatory system and an underwater turbulence flux tower. The tower contained a vertical array of acoustic Doppler velocimeters and fast-response conductivity-temperature sensors, providing a nearly continuous data set of turbulent velocity and density fluctuations and a unique look into the stratified turbulence field. The evolution of various turbulence quantities and direct measurements of the vertical turbulent diffusivity is examined in the presence of nearshore internal bores, both in the near-bed region and ...


Nuclear Matter Effects On J/Psi Production In Asymmetric Cu Plus Au Collisions At Root S-Nn=200 Gev, Andrew Adare, Nicole J. Apadula, Sarah C. Campbell, Lei Ding, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Milap R. Patel, Joshua Perry, Marzia Rosati, Alex Shaver, M. Shimomura, Arbin Timilsina, Shawn Whitaker, Et Al., Phenix Collaboration Dec 2014

Nuclear Matter Effects On J/Psi Production In Asymmetric Cu Plus Au Collisions At Root S-Nn=200 Gev, Andrew Adare, Nicole J. Apadula, Sarah C. Campbell, Lei Ding, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Milap R. Patel, Joshua Perry, Marzia Rosati, Alex Shaver, M. Shimomura, Arbin Timilsina, Shawn Whitaker, Et Al., Phenix Collaboration

Physics and Astronomy Publications

We report on J/psi production from asymmetric Cu + Au heavy-ion collisions at root S-NN = 200 GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of J/psi yields in Cu + Au collisions in the Au-going direction is found to be comparable to that in Au + Au collisions when plotted as a function of the number of participating nucleons. In the Cu-going direction, J/psi production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due ...


Electrostatic Force Microscopy And Electrical Isolation Of Etched Few-Layer Graphene Nano-Domains, D. Patrick Hunley, Abhishek Sundararajan, Mathias J. Boland, Douglas R. Strachan Dec 2014

Electrostatic Force Microscopy And Electrical Isolation Of Etched Few-Layer Graphene Nano-Domains, D. Patrick Hunley, Abhishek Sundararajan, Mathias J. Boland, Douglas R. Strachan

Physics and Astronomy Faculty Publications

Nanostructured bi-layer graphene samples formed through catalytic etching are investigated with electrostatic force microscopy. The measurements and supporting computations show a variation in the microscopy signal for different nano-domains that are indicative of changes in capacitive coupling related to their small sizes. Abrupt capacitance variations detected across etch tracks indicates that the nano-domains have strong electrical isolation between them. Comparison of the measurements to a resistor-capacitor model indicates that the resistance between two bi-layer graphene regions separated by an approximately 10 nm wide etch track is greater than about 1×1012 Ω with a corresponding gap resistivity greater than ...


Gas Detection Applications Of Vertically Aligned Metal Oxide Nanowire Arrays, Haiqiao Su Dec 2014

Gas Detection Applications Of Vertically Aligned Metal Oxide Nanowire Arrays, Haiqiao Su

University of New Orleans Theses and Dissertations

To build novel electronic noses for mimicking biological olfactory systems that consist of olfactory receptor arrays with large surface area and massively-diversified chemical reactivity, three dimensional (3D) vertical aligned ZnO nanowire arrays were employed as active materials for gas detection. ZnO nanowire arrays share 3D structures similar to mammalian olfactory receptor arrays, with thousands of vertical nanowires providing a high reception area which can significantly enhance the sensors’ sensitivity. Meanwhile, with different material decorations (such as SnO2, In2O3, WO3 and polymers), each array of nanowires can produce a distinguishable response for each separate analyte, which ...


Carbon Nanotube Sensors And Field Emitters, Ben Pound Dec 2014

Carbon Nanotube Sensors And Field Emitters, Ben Pound

Physics Capstone Project

Carbon nanotube (CNT) forests are arrays of free-standing CNTs, as seen in Fig. 1a. The goal of this project was to deposit 1,5-diaminonaphthalene (DAN) evenly on each CNT. The motivation is that CNTs cannot effectively participate in chemical reactions by themselves. However, DAN can bind to the CNT surface in such a way that it can participate in chemical reactions while staying on the CNT side wall1. If DAN could be coated evenly on the CNTs throughout the forest, it could make a very sensitive biological sensor. A sensor is only as good as the number of detection ...


Suncircles: A Prose/Poem 12/18/2014, Charles Kay Smith Dec 2014

Suncircles: A Prose/Poem 12/18/2014, Charles Kay Smith

Charles Kay Smith

A current project is writing a book of poetry. The different kind of poetry I’m trying to write melds science, humanities, and aesthetic aims of clarity and a polished plain style with social consciousness. I’m uploading one of the poems in the collection as an example of the kind of poetry I’m trying to compose.


Evidence For (And Against) Progenitor Bias In The Size Growth Of Compact Red Galaxies, Stephanie K. Keating, Roberto G. Abraham, Ricardo Schiavon, Genevieve Graves, Ivana Damjanov, Renbin Yan, Jeffrey Newman, Luc Simard Dec 2014

Evidence For (And Against) Progenitor Bias In The Size Growth Of Compact Red Galaxies, Stephanie K. Keating, Roberto G. Abraham, Ricardo Schiavon, Genevieve Graves, Ivana Damjanov, Renbin Yan, Jeffrey Newman, Luc Simard

Physics and Astronomy Faculty Publications

Most massive, passive galaxies are compact at high redshifts, but similarly compact massive galaxies are rare in the local universe. The most common interpretation of this phenomenon is that massive galaxies have grown in size by a factor of about five since redshift z = 2. An alternative explanation is that recently quenched massive galaxies are larger (a "progenitor bias"). In this paper, we explore the importance of progenitor bias by looking for systematic differences in the stellar populations of compact early-type galaxies in the DEEP2 survey as a function of size. Our analysis is based on applying the statistical technique ...


Neutral Density Behavior From 45-90 Km Based On Rayleigh Lidar Observations Above Usu, David Barton Dec 2014

Neutral Density Behavior From 45-90 Km Based On Rayleigh Lidar Observations Above Usu, David Barton

Physics Capstone Project

There are over 900 nights of observations taken by the Rayleigh lidar above Utah State University from 1993 to 2004. The data have been reduced to give absolute temperatures and relative densities in the mesosphere, from 45-90 km (Herron, 2004, 2007). From the 11 years of relative density data an 11-year climatology of mesospheric densities above Logan, Utah has been created. From this climatology I have been able to normalize the 11 years of density data to the following models: the MSISe00 empirical model, the CPC (Climate Prediction Center) reanalysis model, the ERA Interim reanalysis model, and the NASA MERRA ...


Tuning Electronic Correlation With Pressure, Gilberto Fernandes Lopes Fabbris Dec 2014

Tuning Electronic Correlation With Pressure, Gilberto Fernandes Lopes Fabbris

Arts & Sciences Electronic Theses and Dissertations

Strongly correlated electron systems display some of the most exotic ground states in condensed matter. In this thesis high pressure is used to tune the degree of electron correlations in systems of current interest. Their electronic and structural properties were investigated at high pressure using x-ray spectroscopy and scattering as well as transport techniques in a diamond anvil cell. The interplay between short- and long-range structural order, one-dimensional charge ordering, and superconductivity was studied in La1.875Ba0.125CuO4. At ambient pressure, this material displays charge ordering at the onset of a low temperature structural phase ...


Comparison Of Conventional And Bayesian Analysis For The Ultrasonic Characterization Of Cancellous Bone, Amber Groopman Dec 2014

Comparison Of Conventional And Bayesian Analysis For The Ultrasonic Characterization Of Cancellous Bone, Amber Groopman

Arts & Sciences Electronic Theses and Dissertations

This dissertation investigates the physics underlying the propagation of ultrasonic waves in cancellous bone. Although quantitative ultrasound has the potential to evaluate bone quality even better than the current gold standard X-ray based modality, its clinical utility has been hampered by the incomplete understanding of the mechanisms governing the interaction between ultrasound and bone. Therefore, studies that extend the understanding of the fundamental physics of the relationship between ultrasound and trabecular bone tissue may result in improved clinical capabilities.

Ultrasonic measurements were carried out on excised human calcaneal specimens in order to study the effects of overlapping fast and slow ...


X-Ray Polarimetry With X-Calibur, Qingzhen Guo Dec 2014

X-Ray Polarimetry With X-Calibur, Qingzhen Guo

Arts & Sciences Electronic Theses and Dissertations

ABSTRACT

X-Ray Polarimetry with X-Calibur

by

Qingzhen Guo

Doctor of Philosophy in Physics, Washington University in St. Louis,

September, 2014. Professor Henric Krawczynski, Chair

X-ray polarimetry is a prime tool to investigate the unexplored compact sources and to provide crucial information that other techniques can not produce. By measuring the degree and orientation of the polarization of radiation from a cosmic source, unique inferences about the morphology and the magnetic field structure can be made.

Krawczysnki's group at Washington University is working on a uniquely sensitive scattering polarimeter, X-Calibur, to be used in the focal plane of a focusing ...


Measurement Of Polarization Observables PZ, PSZ, And PCZ In Double-Pion Photoproduction Off The Proton, Yuqing Mao Dec 2014

Measurement Of Polarization Observables PZ, PSZ, And PCZ In Double-Pion Photoproduction Off The Proton, Yuqing Mao

Theses and Dissertations

Meson production from excited nucleons is important in the study of baryon resonances and pion photoproduction is attracting much attention. To date a rather large amount of unpolarized cross-section measurements have been reported for both single- and double-pion photoproduction. However, polarization observables provide complementary information as they probe different combinations of transition amplitudes. The database for polarization observables remains quite sparse. Double-pion photoproduction have been studied in Hall B at Jefferson Lab with linearly polarized tagged photon beams incident on longitudinally polarized protons. The experiment covered center-of-mass energies between 1.4 GeV and 2.3 GeV. The target was a ...