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Full-Text Articles in Physical Sciences and Mathematics
Quantum Turbulence In Two Dimensional Bose-Einstein Condensates, Bo Zhang
Quantum Turbulence In Two Dimensional Bose-Einstein Condensates, Bo Zhang
Dissertations, Theses, and Masters Projects
We examine the energy cascades and quantum vortex structures in two-dimensional quantum turbulence through a special unitary time evolution algorithm. An early attempt at using the Lattice Boltzmann Method proved successful in correctly representing some features of the Nonlinear Schrodinger System (NLS), such as the phase shift following the one-dimensional soliton-soliton collision, as well as the two-dimentional modulation instability. However, to accurately evaluate NLS, the implicit Euler method is required to resolve the time evolution, which is computationally expensive. A more accurate and efficient method, the Quantum Lattice Gas model is employed to simulate the quantum turbulence governed by the …
Microscopic Dynamics And Transport Of Hydrogen In Proton Conducting Oxides, Erik J. Spahr
Microscopic Dynamics And Transport Of Hydrogen In Proton Conducting Oxides, Erik J. Spahr
Dissertations, Theses, and Masters Projects
The microscopic motion of hydrogen in solid oxides plays an important role in defect migration and reaction processes. Understanding the vibrational dynamics associated with both hydrogen-oxygen (O-H) bonds and the surrounding ionic environment allows one to better characterize these fundamental interactions. This thesis presents a comprehensive investigation into the vibrational decay dynamics of O-H and O-D stretch modes in crystalline oxides using time-resolved infrared pump-probe spectroscopy.;Measurements of the vibrational lifetimes of hydrogen related local modes in potassium tantalate (KTaO3) and titanium dioxide (TiO2 ) show that the localized O-H vibration is very closely tied to proton transport. In KTaO3 we …
Thin Film And Chemical Ordering Effects On The Magnetic Anisotropy In Binary Alloys, Jonathan Ronald Skuza
Thin Film And Chemical Ordering Effects On The Magnetic Anisotropy In Binary Alloys, Jonathan Ronald Skuza
Dissertations, Theses, and Masters Projects
This dissertation presents various investigations into the structure-property correlations in highly anisotropic FePt and FePd thin films and nanostructures. These binary alloy thin films may exhibit long-range chemical ordering (e.g. L10), which induces a strong uniaxial magnetic anisotropy whose orientation is dependent on the ordering direction in the thin film. The chemical ordering, and hence the magnetic anisotropy, in these thin films can be controlled and tailored through sputter deposition and ion implantation conditions followed by subsequent processing. Two novel fabrication methods, x-ray rapid thermal annealing (XRTA) and heavy ion implantation, successfully demonstrate the ability to obtain highly anisotropic nanometer-sized …
Measurement Of The Target-Normal Single-Spin Asymmetry A(N,Y) In The Deep Inelastic Region From The Reaction Helium-3 (E,E'), Joseph M. Katich
Measurement Of The Target-Normal Single-Spin Asymmetry A(N,Y) In The Deep Inelastic Region From The Reaction Helium-3 (E,E'), Joseph M. Katich
Dissertations, Theses, and Masters Projects
A first measurement of the inclusive target single-spin asymmetry, Any , has been performed in deep-inelastic scattering of electrons from a 3He target polarized normal to the electron scattering plane. This asymmetry is void of contributions at the Born level, and thus is a direct observable for two-photon physics. The experiment was performed in Hall A at Thomas Jefferson National Accelerator Facility from October 2008 through early February 2009.;The measurement is the first from a polarized neutron target. The final overall precision is several times better than previously existing SLAC proton data, and significantly extends the kinematic range over which …
Search For Effects Beyond The Born Approximation In Polarization Transfer Observables In Ep Elastic Scattering, Mehdi Meziane
Search For Effects Beyond The Born Approximation In Polarization Transfer Observables In Ep Elastic Scattering, Mehdi Meziane
Dissertations, Theses, and Masters Projects
Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, GE/GM, obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange (TPEX) contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, this thesis reports measurements, of the GEp2gamma experiment, of polarization transfer observables in the elastic H ( e&ar;,e' p&ar; ) reaction for three different beam energies at a fixed squared momentum transfer Q² = 2.5 GeV², spanning a wide range …
Slow And Stored Light Under Conditions Of Electromagnetically Induced Transparency And Four Wave Mixing In An Atomic Vapor, Nathaniel Blair Phillips
Slow And Stored Light Under Conditions Of Electromagnetically Induced Transparency And Four Wave Mixing In An Atomic Vapor, Nathaniel Blair Phillips
Dissertations, Theses, and Masters Projects
The recent prospect of efficient, reliable, and secure quantum communication relies on the ability to coherently and reversibly map nonclassical states of light onto long-lived atomic states. A promising technique that accomplishes this employs Electromagnetically Induced Transparency (EIT), in which a strong classical control field modifies the optical properties of a weak signal field in such a way that a previously opaque medium becomes transparent to the signal field. The accompanying steep dispersion in the index of refraction allows for pulses of light to be decelerated, then stored as an atomic excitation, and later retrieved as a photonic mode. This …
Enhanced Field Emission From Vertically Oriented Graphene By Thin Solid Film Coatings, Michael Bagge-Hansen
Enhanced Field Emission From Vertically Oriented Graphene By Thin Solid Film Coatings, Michael Bagge-Hansen
Dissertations, Theses, and Masters Projects
Recent progress and a coordinated national research program have brought considerable effort to bear on the synthesis and application of carbon nanostructures for field emission. at the College of William and Mary, we have developed field emission arrays of vertically oriented graphene (carbon nanosheets, CNS) that have demonstrated promising cathode performance, delivering emission current densities up to 2 mA/mm2 and cathode lifetime > 800 hours. The work function ( & phis;) of CNS and other carbonaceous cathode materials has been reported to be &phis;∼4.5-5.1 eV. The application of low work function thin films can achieve several orders of magnitude enhancement of …
Charmed Hadron Spectrum And Interactions, Liuming Liu
Charmed Hadron Spectrum And Interactions, Liuming Liu
Dissertations, Theses, and Masters Projects
Studying hadrons containing heavy quarks in lattice QCD is challenging mainly due to finite lattice spacing effects. to control the discretization errors, mQa is required to be much less than 1, where mQ is the quark mass and a is the lattice spacing. For currently accessible lattice spacings, the charm quark mass doesn't satisfy this requirement. One approach to simulate heavy quarks on the lattice is non-relativestic QCD, which treats heavy quark as a static source and expand the lattice quark action in powers of 1mQa . Unfortunately, the charm quark is not heavy enough to justify this expansion. An …
A Measurement Of Neutrino Oscillations With Muon Neutrinos In The Minos Experiment, Stephen James Coleman
A Measurement Of Neutrino Oscillations With Muon Neutrinos In The Minos Experiment, Stephen James Coleman
Dissertations, Theses, and Masters Projects
Experimental evidence has established that neutrino flavor states evolve over time. A neutrino of a particular flavor that travels some distance can be detected in a different neutrino flavor state. The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline experiment that is designed to study this phenomenon, called neutrino oscillations. MI-NOS is based at Fermilab near Chicago, IL, and consists of two detectors: the Near Detector located at Fermilab, and the Far Detector, which is located in an old iron mine in Soudan, MN. Both detectors are exposed to a beam of muon neutrinos from the NuMI beamline, and …
First-Principles Calculations Of Nuclear Magnetic Resonance Chemical Shielding Tensors In Complex Ferroelectric Perovskites, Daniel Lawrence Pechkis
First-Principles Calculations Of Nuclear Magnetic Resonance Chemical Shielding Tensors In Complex Ferroelectric Perovskites, Daniel Lawrence Pechkis
Dissertations, Theses, and Masters Projects
Nuclear magnetic resonance (NMR) spectroscopy is one of the most important experimental probes of local atomistic structure, chemical ordering, and dynamics. Recently, NMR has increasingly been used to study complex ferroelectric perovskite alloys, where spectra can be difficult to interpret. First-principles calculations of NMR spectra can greatly assist in this task. In this work, oxygen, titanium, and niobium NMR chemical shielding tensors, s&d4; , were calculated with first-principles methods for ferroelectric transition metal prototypical ABO3 perovskites [SrTiO3, BaTiO 3, PbTiO3 and PbZrO3] and A(B,B')O3 perovskite alloys Pb(Zr1/2Ti1/2)O3 (PZT) and Pb(Mg1/3Nb2/3)O3 (PMN). The principal findings are 1) a large anisotropy between …