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Articles 1 - 27 of 27
Full-Text Articles in Physical Sciences and Mathematics
Superconducting Thin Films For The Enhancement Of Superconducting Radio Frequency Accelerator Cavities, Matthew Burton
Superconducting Thin Films For The Enhancement Of Superconducting Radio Frequency Accelerator Cavities, Matthew Burton
Dissertations, Theses, and Masters Projects
Bulk niobium (Nb) superconducting radio frequency (SRF) cavities are currently the preferred method for acceleration of charged particles at accelerating facilities around the world. However, bulk Nb cavities have poor thermal conductance, impose material and design restrictions on other components of a particle accelerator, have low reproducibility and are approaching the fundamental material-dependent accelerating field limit of approximately 50MV/m. Since the SRF phenomena occurs at surfaces within a shallow depth of ~1 µm, a proposed solution to this problem has been to utilize thin film technology to deposit superconducting thin films on the interior of cavities to engineer the active …
Modeling The Gross-Pitaevskii Equation Using The Quantum Lattice Gas Method, Armen M. Oganesov
Modeling The Gross-Pitaevskii Equation Using The Quantum Lattice Gas Method, Armen M. Oganesov
Dissertations, Theses, and Masters Projects
We present an improved Quantum Lattice Gas (QLG) algorithm as a mesoscopic unitary perturbative representation of the mean field Gross Pitaevskii (GP) equation for Bose–Einstein Condensates (BECs). The method employs an interleaved sequence of unitary collide and stream operators. QLG is applicable to many different scalar potentials in the weak interaction regime and has been used to model the Korteweg–de Vries (KdV), Burgers and GP equations. It can be implemented on both quantum and classical computers and is extremely scalable. We present results for 1D soliton solutions with positive and negative internal interactions, as well as vector solitons with inelastic …
Computational Methods Of Lattice Boltzmann Mhd, Christopher Robert Flint
Computational Methods Of Lattice Boltzmann Mhd, Christopher Robert Flint
Dissertations, Theses, and Masters Projects
Lattice Boltzmann (LB) Methods are a somewhat novel approach to Computational Fluid Dynamics (CFD) simulations. These methods simulate Navier-Stokes and magnetohydrodynamics (MHD) equations on the mesoscopic (quasi-kinetic) scale by solving for a statistical distribution of particles rather than attempting to solve the nonlinear macroscopic equations directly. These LB methods allow for a highly parallelizable code since one replaces the difficult nonlinear convective derivatives of MHD by simple linear advection on a lattice. New developments in LB have significantly extended the numerical stability limits of its applicability. These developments include multiple relaxation times (MRT) in the collision operators, maximizing entropy to …
Tetraquark Operators In Lattice Qcd And Exotic Flavour States In The Charm Sector, Gavin K. C. Cheung, Christopher E. Thomas, Jozef J. Dudek, Robert G. Edwards
Tetraquark Operators In Lattice Qcd And Exotic Flavour States In The Charm Sector, Gavin K. C. Cheung, Christopher E. Thomas, Jozef J. Dudek, Robert G. Edwards
Arts & Sciences Articles
We present a general class of operators resembling compact tetraquarks which have a range of colour-flavour-spin structures, transform irreducibly under the symmetries of the lattice and respect other relevant symmetries. These constructions are demonstrated in lattice QCD calculations with light quarks corresponding to m(pi) = 391 MeV. Using the distillation framework, correlation functions involving large bases of meson-meson and tetraquark operators are computed in the isospin-1 hidden-charm and doubly-charmed sectors, and finite-volume spectra are extracted with the variational method. We find the spectra are insensitive to the addition of tetraquark operators to the bases of meson-meson operators. For the first …
First Measurement Of Proton's Charge Form Factor At Very Low Q(2) With Initial State Radiation, M. Mihovilovic, K. Griffioen, Et Al.
First Measurement Of Proton's Charge Form Factor At Very Low Q(2) With Initial State Radiation, M. Mihovilovic, K. Griffioen, Et Al.
Arts & Sciences Articles
We report on a new experimental method based on initial-state radiation (ISR) in e-p scattering, which exploits the radiative tail of the elastic peak to study the properties of electromagnetic processes and to extract the proton charge form factor (G(E)(P)) at extremely small Q(2). The ISR technique was implemented in an experiment at the three-spectrometer facility of the Mainz Microtron (MAMI). This led to a precise validation of radiative corrections far away from elastic line and provided first measurements of G(E)(P) for 0.001 <= Q(2) <= 0.004 (GeV/c)(2). (C) 2017 The Authors. Published by Elsevier B.V.
Drifts, Currents, And Power Scrape-Off Width In Solps-Iter Modeling Of Diii-D, E. T. Meier, R. J. Goldston, E. G. Kaveeva, M. A. Makowski, S. Mordijck
Drifts, Currents, And Power Scrape-Off Width In Solps-Iter Modeling Of Diii-D, E. T. Meier, R. J. Goldston, E. G. Kaveeva, M. A. Makowski, S. Mordijck
Arts & Sciences Articles
The effects of drifts and associated flows and currents on the width of the parallel heat flux channel (lambda(q)) in the tokamak scrape-offlayer (SOL) are analyzed using the SOLPS-ITER 2D fluid transport code. Motivation is supplied by Goldston's heuristic drift (HD) model for lambda(q), which yields the same approximately inverse poloidal magnetic field dependence seen in multi-machine regression. The analysis, focusing on a DIII-D H-mode discharge, reveals HD-like features, including comparable density and temperature fall-off lengths in the SOL, and up-down ion pressure asymmetry that allows net cross-separatrix ion magnetic drift flux to exceed net anomalous ion flux. In experimentally …
Broadband Near-Field Infrared Spectroscopy With A High Temperature Plasma Light Source, D. J. Lahneman, T. J. Huffman, Peng Xu, M. M. Qazilbash
Broadband Near-Field Infrared Spectroscopy With A High Temperature Plasma Light Source, D. J. Lahneman, T. J. Huffman, Peng Xu, M. M. Qazilbash
Arts & Sciences Articles
Scattering-type scanning near-field optical microscopy (S-SNOM) has enormous potential as a spectroscopy tool in the infrared spectral range where it can probe phonon resonances and carrier dynamics at the nanometer lengths scales. However, its applicability is limited by the lack of practical and affordable table-top light sources emitting intense broadband infrared radiation in the 100 cm(-1) to 2,500 cm(-1) spectral range. This paper introduces a high temperature plasma light source that is both ultra-broadband and has much more radiant power in the infrared spectral range than conventional, table-top thermal light sources such as the globar. We implement this plasma lamp …
Disconnected Diagrams In Lattice Qcd, Arjun Singh Gambhir
Disconnected Diagrams In Lattice Qcd, Arjun Singh Gambhir
Dissertations, Theses, and Masters Projects
In this work, we present state-of-the-art numerical methods and their applications for computing a particular class of observables using lattice quantum chromodynamics (Lattice QCD), a discretized version of the fundamental theory of quarks and gluons. These observables require calculating so called "disconnected diagrams" and are important for understanding many aspects of hadron structure, such as the strange content of the proton. We begin by introducing the reader to the key concepts of Lattice QCD and rigorously define the meaning of disconnected diagrams through an example of the Wick contractions of the nucleon. Subsequently, the calculation of observables requiring disconnected diagrams …
Quantum And Classical Manifestation Of Hamiltonian Monodromy, Chen Chen
Quantum And Classical Manifestation Of Hamiltonian Monodromy, Chen Chen
Dissertations, Theses, and Masters Projects
Integrable Hamiltonian systems are said to display nontrivial monodromy if fundamental action-angle loops defined on phase-space tori change their topological structure when the system is carried around a circuit. It was shown in earlier work that this topological change can be seen in families of trajectories of noninteracting particles; however, that work required use of a very abstract flow in phase space. In this dissertation, we show that the same topological change can occur as a result of application of ordinary forces. We also show how this dynamical phenomenon could be observed experimentally in cold atom systems. Almost everything that …
A Global Normal Form For Two-Dimensional Mode Conversion, David Gregory Johnston
A Global Normal Form For Two-Dimensional Mode Conversion, David Gregory Johnston
Dissertations, Theses, and Masters Projects
Mode conversion is a phenomenon that is of interest as a method for heating in fusion reactors. A magnetosonic wave with dispersion relation DMS propagates toward the interior of the plasma, where it excites an ion-hybrid wave with dispersion relation DIH and thereby transfers energy to the plasma. We wish to study this process using ray-based methods. The 2 2 dispersion matrix D, which is, in general, a function of the phase space variables (x; y; kx; ky), must be put into normal form, in which the diagonals of D, identied as the uncoupled dispersion relations, DMS and DIH, Poisson-commute …
Measurement Of The Elastic Ep Cross Section At Q2 = 0.66, 1.10, 1.51 And 1.65 Gev2, Yang Wang
Measurement Of The Elastic Ep Cross Section At Q2 = 0.66, 1.10, 1.51 And 1.65 Gev2, Yang Wang
Dissertations, Theses, and Masters Projects
The nucleon form factors have been investigated by physicists for decades because of its fundamental importance. The world data of the proton magnetic form factor GMp shows that the measurements have been focused on Q2 lower than 5 GeV2 and it has large uncertainties at higher GeV2. Experiment E12-07-108 aims to improve the accuracy of the e − p elastic cross section to better than 2% over a Q2 range of 7 − 14 GeV2. From 2015 to 2016, the e − p elastic cross section was measured over a wide range of Q2 from 0.66 − 12.56 GeV2 at …
Infrared Spectroscopy And Nano-Imaging Of La0.67sr0.33mno3 Films, Peng Xu
Infrared Spectroscopy And Nano-Imaging Of La0.67sr0.33mno3 Films, Peng Xu
Dissertations, Theses, and Masters Projects
Charge transport properties of manganites can be significantly modified by temperature, chemical doping, strain, and interfacial boundaries. In this dissertation, we report studies on broadband far-field infrared spectroscopy and near-field infrared imaging of single crystalline thin films of Sr doped manganite LaMnO3 at 0.33 doping level. at this Sr-doping level, the manganite films undergo a phase transition between a ferromagnetic metallic phase at low temperatures to a paramagnetic, insulating phase at higher temperatures. The films were grown on different substrates with different thicknesses by pulsed laser deposition method. The temperature dependent far-field infrared data on 85 nm thick La0.67Sr0.33MnO3 (LSMO) …
Plasmonic Approaches And Photoemission: Ag-Based Photocathodes, Zhaozhu Li
Plasmonic Approaches And Photoemission: Ag-Based Photocathodes, Zhaozhu Li
Dissertations, Theses, and Masters Projects
Photocathodes play an important role in present large accelerator facilities by providing polarized or un-polarized electron beams. Current state-of-art high polarization photocathodes consist of strained super-lattice GaAs based photocathodes, e.g. GaAs/GaAsP has a quantum efficiency ~1% and polarization ~90% at near-infrared wavelength for the incident light. Despite the advantages offered by metallic photocathodes regarding longer life time, fast response time and low requirements of ultra-high vacuum environment, they have not been put to use due to their low quantum efficiency, even though one can envision several approaches to achieve spin-polarization from them. A possible solution is to apply the Fano …
Isovector Charges Of The Nucleon From 2+1-Flavor Qcd With Clover Fermions, Boram Yoon, Yong-Chull Jang, (...), Kostas Orginos, Et Al.
Isovector Charges Of The Nucleon From 2+1-Flavor Qcd With Clover Fermions, Boram Yoon, Yong-Chull Jang, (...), Kostas Orginos, Et Al.
Arts & Sciences Articles
We present high-statistics estimates of the isovector charges of the nucleon from four 2 + 1-flavor ensembles generated using Wilson-clover fermions with stout smearing and tree-level tadpole improved Symanzik gauge action at lattice spacings a approximate to 0.127 and 0.09 fm and with M-pi approximate to 280 and 170 MeV. The truncated solver method with bias correction and the coherent source sequential propagator construction are used to cost-effectively achieve O (10(5)) measurements on each ensemble. Using these data, the analysis of two-point correlation functions is extended to include four states in the fits, and of three-point functions to three states. …
Measurement Of The Beam Asymmetry Sigma For Pi(0) And Eta Photoproduction On The Proton At E-Gamma=9 Gev, H. Al Ghoul, (...), Justin R. Stevens, Et Al.
Measurement Of The Beam Asymmetry Sigma For Pi(0) And Eta Photoproduction On The Proton At E-Gamma=9 Gev, H. Al Ghoul, (...), Justin R. Stevens, Et Al.
Arts & Sciences Articles
We report measurements of the photon beam asymmetry Sigma for the reactions (gamma) over right arrowp -> p pi(0) and gamma p -> p eta from the GLUEX experiment using a 9 GeV linearly polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous pi(0) measurements and are the first. measurements in this energy regime. The results are compared with theoretical predictions based on t-channel, quasiparticle exchange and constrain the axial-vector component of the neutral meson production mechanism in …
Optical Control Of Multi-Photon Coherent Interactions In Rubidium Atoms, Gleb Vladimirovich Romanov
Optical Control Of Multi-Photon Coherent Interactions In Rubidium Atoms, Gleb Vladimirovich Romanov
Dissertations, Theses, and Masters Projects
In the last few decades, coherent light-atom interactions have opened unprecedented possibilities for the coherent control of atomic and optical quantum systems, paved the way for the practical realization of quantum information technologies, and allowed for the creation of novel quantum-enhanced sensors. This dissertation investigates the interaction of multiple near-resonant optical fields with hot rubidium atoms under the conditions of electromagnetically induced transparency. The main goal of the presented research is to address some fundamental challenges in using such systems for practical applications. The EIT effect relies on the strong coupling of an optical probe field and a collective long-lived …
Formulating Schwinger-Dyson Equations For Qed Propagators In Minkowski Space, Shaoyang Jia
Formulating Schwinger-Dyson Equations For Qed Propagators In Minkowski Space, Shaoyang Jia
Dissertations, Theses, and Masters Projects
The Schwinger-Dyson equations (SDEs) are coupled integral equations for the Green's functions of a quantum field theory (QFT). The SDE approach is the analytic nonperturbative method for solving strongly coupled QFTs. When applied to QCD, this approach, also based on first principles, is the analytic alternative to lattice QCD. However, the SDEs for the n-point Green's functions involves (n+1)-point Green's functions (sometimes (n+2)-point functions as well). Therefore any practical method for solving this infinitely coupled system of equations requires a truncation scheme. When considering strongly coupled QED as a modeling of QCD, naive truncation schemes violate various principles of the …
Shining Light On The Phase Transitions Of Vanadium Dioxide, Tyler J. Huffman
Shining Light On The Phase Transitions Of Vanadium Dioxide, Tyler J. Huffman
Dissertations, Theses, and Masters Projects
The salient feature of the familiar structural transition accompanying the thermally-driven metal-insulator transition in bulk vanadium dioxide (VO2) is a pairing of all the vanadium ions in the monoclinic M¬1 insulating phase. Whether this pairing (unit cell doubling) alone is sufficient to open the energy gap has been the central question of a classic debate which has continued for almost sixty years. Interestingly, there are two less familiar insulating states, monoclinic M2 and triclinic, which are accessible via strain or chemical doping. These phases are noteworthy in that they exhibit distinctly different V-V pairing. With infrared and optical photon spectroscopy, …
Squeezing Light With Atoms: Generation Of Non-Classical Light Via Four-Wave Mixing, Nathan Super
Squeezing Light With Atoms: Generation Of Non-Classical Light Via Four-Wave Mixing, Nathan Super
Science Research Symposium
The goal of the project is to produce a pair of polarization-entangled light fields using four-wave mixing in hot Rb vapor. In this process, interaction of atoms with near-resonant strong control optical field results in strong amplification of a nearly-collinear probe optical field and in generation of a quantum correlated conjugate Stokes optical field. In order to establish the quantum correlation between the Stokes and probe fields, we have adopted a homodyne detection scheme. If the differential noise between the Stokes and probe fields is below the quantum noise limit, then intensity fluctuation entanglement has been achieved, and it is …
Determination Of The Kinematics Of The Qweak Experiment And Investigation Of An Atomic Hydrogen Møller Polarimeter, Valerie Marie Gray
Determination Of The Kinematics Of The Qweak Experiment And Investigation Of An Atomic Hydrogen Møller Polarimeter, Valerie Marie Gray
Dissertations, Theses, and Masters Projects
The Qweak experiment has tested the Standard Model through making a precise measurement of the weak charge of the proton (QpW). This was done through measuring the parity-violating asymmetry for polarized electrons scattering off of unpolarized protons. The parity-violating asymmetry measured is directly proportional to the four-momentum transfer (Q^2) from the electron to the proton. The extraction of QpW from the measured asymmetry requires a precise Q^2 determination. The Qweak experiment had a Q^2 = 24.8 ± 0.1 m(GeV^2) which achieved the goal of an uncertainty of ≤ 0.5%. From the measured asymmetry and Q^2 , QpW was determined to …
Hampton Roads Crossing Study Supplemental Environmental Impact Statement: Evaluation Of Potential Impact On Surface Water Elevation, Flow, Salinity, And Bottom Shear Stress, Yinglong J. Zhang, Harry V. Wang, Zhuo Liu, Mac Sisson, Jian Shen
Hampton Roads Crossing Study Supplemental Environmental Impact Statement: Evaluation Of Potential Impact On Surface Water Elevation, Flow, Salinity, And Bottom Shear Stress, Yinglong J. Zhang, Harry V. Wang, Zhuo Liu, Mac Sisson, Jian Shen
Reports
The purpose of this study is to evaluate the potential impacts of the proposed alternatives for the highway crossing in Hampton Roads on physical characteristics of surface water elevation, flow, salinity, and bottom shear stress. The analysis is part of the Virginia Department of Transportation (VDOT), the Federal Highway Administration, and other stakeholders’ Supplemental Environmental Impact Statement (SEIS) for Hampton Roads Crossing Study (HRCS).
Investigation Of Local Structures In Cation-Ordered Microwave Dielectric A Solid-State Nmr And First Principle Calculation Study, Rony Gustam Kalfarisi
Investigation Of Local Structures In Cation-Ordered Microwave Dielectric A Solid-State Nmr And First Principle Calculation Study, Rony Gustam Kalfarisi
Dissertations, Theses, and Masters Projects
Solid-state Nuclear Magnetic Resonance (ssNMR) spectroscopy has proven to be a powerful method to probe the local structure and dynamics of a system. In powdered solids, the nuclear spins experience various anisotropic interactions which depend on the molecular orientation. These anisotropic interactions make ssNMR very useful as they give a specific appearance to the resonance lines of the spectra. The position and shape of these resonance lines can be related to local structure and dynamics of the system under study. My research interest has focused around studying local structures and dynamics of quadrupolar nuclei in materials using ssNMR spectroscopy. Li …
Computational Studies Of Strongly Correlated Quantum Matter, Hao Shi
Computational Studies Of Strongly Correlated Quantum Matter, Hao Shi
Dissertations, Theses, and Masters Projects
The study of strongly correlated quantum many-body systems is an outstanding challenge. Highly accurate results are needed for the understanding of practical and fundamental problems in condensed-matter physics, high energy physics, material science, quantum chemistry and so on. Our familiar mean-field or perturbative methods tend to be ineffective. Numerical simulations provide a promising approach for studying such systems. The fundamental difficulty of numerical simulation is that the dimension of the Hilbert space needed to describe interacting systems increases exponentially with the system size. Quantum Monte Carlo (QMC) methods are one of the best approaches to tackle the problem of enormous …
Highly-Correlated Electron Behavior In Niobium And Niobium Compound Thin Films, Melissa R. Beebe
Highly-Correlated Electron Behavior In Niobium And Niobium Compound Thin Films, Melissa R. Beebe
Dissertations, Theses, and Masters Projects
Electron correlations are the root of many interesting phenomena in materials, including phase transitions such as superconductivity and insulator-to-metal transitions, which are of great interest both for scientific understanding and for many applications. Such phase transitions can often be tailored in thin films, in which the geometry of the material is limited in one dimension. By studying how the physical structure of a thin film affects its correlated electron response, it is possible to obtain useful insight into both the nature of the electron correlations present in the material and how to control them for various applications. Niobium, an elemental …
Isoscalar Pi Pi Scattering And The Sigma Meson Resonance From Qcd, Raul A. Briceño, Jozef J. Dudek, Robert G. Edwards, David J. Wilson
Isoscalar Pi Pi Scattering And The Sigma Meson Resonance From Qcd, Raul A. Briceño, Jozef J. Dudek, Robert G. Edwards, David J. Wilson
Arts & Sciences Articles
We present for the first time a determination of the energy dependence of the isoscalar pi pi elastic scattering phase shift within a first-principles numerical lattice approach to QCD. Hadronic correlation functions are computed including all required quark propagation diagrams, and from these the discrete spectrum of states in the finite volume defined by the lattice boundary is extracted. From the volume dependence of the spectrum, we obtain the S-wave phase shift up to the K (K) over bar threshold. Calculations are performed at two values of the u, d quark mass corresponding to m(pi) = 236; 391 MeV, and …
Q(Weak): First Direct Measurement Of The Proton's Weak Charge, J. F. Dowd
Q(Weak): First Direct Measurement Of The Proton's Weak Charge, J. F. Dowd
Arts & Sciences Articles
The Q(weak) experiment, which took data at Jefferson Lab in the period 2010 - 2012, will precisely determine the weak charge of the proton by measuring the parity-violating asymmetry in elastic e-p scattering at 1.1 GeV using a longitudinally polarized electron beam and a liquid hydrogen target at a low momentum transfer of Q(2) = 0.025 ( GeV/c)(2). The weak charge of the proton is predicted by the Standard Model and any significant deviation would indicate physics beyond the Standard Model. The technical challenges and experimental apparatus for measuring the weak charge of the proton will be discussed, as well …
Multispectrum Analysis Of The Oxygen A-Band, Brian J. Drouin, D. Chris Benner, Linda R. Brown, (...), V. Malathy Devi, Et Al.
Multispectrum Analysis Of The Oxygen A-Band, Brian J. Drouin, D. Chris Benner, Linda R. Brown, (...), V. Malathy Devi, Et Al.
Arts & Sciences Articles
Retrievals of atmospheric composition from near-infrared measurements require measurements of airmass to better than the desired precision of the composition. The oxygen bands are obvious choices to quantify airmass since the mixing ratio of oxygen is fixed over the full range of atmospheric conditions. The OCO-2 mission is currently retrieving carbon dioxide concentration using the oxygen A-band for airmass normalization. The 0.25% accuracy desired for the carbon dioxide concentration has pushed the required state-of-the-art for oxygen spectroscopy. To measure 02 A-band cross-sections with such accuracy through the full range of atmospheric pressure requires a sophisticated line shape model (Rautian or …