Physical Sciences and Mathematics Commons^™

Two-Electrode Measurements Of Electrostatic Double Layer Potentials With Atomic Force Microscopy, Jason Giamberardino

Theses and Dissertations

In this dissertation, I provide a thorough description of my development of theoretical, analytical, and experimental techniques pertaining to novel measurements of the electrostatic double layer (EDL) using atomic force microscopy (AFM), among other techniques. The EDL refers to the structure formed by ions that exists at the interface between a solid and a liquid. The EDL is an important physical element of many systems and its behavior has been of interest to scientists for many decades. Because many areas of science and engineering are moving to test, build, and understand systems at smaller and smaller scales, this work focuses …

Birefringence Microscopy With Magnetic-Field Aligned Multiferroic Janus Nanofibers, Yu-Chun Yeh

Theses and Dissertations

Multiferroic Janus nanofibers consisting of barium titanate (BaT iO3) and cobalt ferrite (CoFe2O4) have the magnetoelectric effect between piezoelectric and magnetostrictive phases. By applying an external magnetic field on Janus nanofibers,the dipole moment in piezoelectric phase would be formed and produce the electric field. Since poly(N-vinylcarbazole) (PVK) polymer has anisotropic property, the birefringence can be induced by the electric field. We generalize the magnetic field birefringence quadratic equation and coupling constant for PVK polymer with Janus nanofibers. Birefringence microscopy is used to observe the PVK birefringence under an external magnetic field from 0 to 2500 Oe. The numerical results show …

Optical Investigation Of A Hybrid System Of Plasmonic Structures And Semiconductor Quantum Dots, Matthew B. Seaton

Theses and Dissertations

Next generation integrated nanophotonic devices must fabricate large numbers of nanoscaled light coupling structures onto a single wafer: emitters such as quantum dots, resonators such as nanocavities and plasmonic nanoparticles, photonic crystal and nano-plasmonic waveguides, among others. Before precision planning and engi- neering will be possible a thorough understanding of the interaction between these structures must be documented. We present in this work an investigation of the interaction between quantum dots and plasmonic structures in the weak coupling regime. We found that surface plasmon supporting silver structures placed about 100nm from InGaAs quantum dots enabled an all optical polarization dependent …

Depairing Current Density In Nbtin Superconducting Films, Nahid Shayesteh Swails

Theses and Dissertations

In this work, we systematically investigate the superconducting properties of Niobium Titanium Nitride (NbTiN) superconducting films with different geometries, which at low temperature remain superconducting. NbT iN superconducting films with a few nm thickness are widely used in devices such as superconductor-insulatorsuperconductor (SIS) mixers, superconducting cavities and resonators and superconducting nanowire single-photon detectors (SNSPD). In all these applications, films of varying dimensions are required to achieve optimal performance. The initial thickness of our samples was 125 nm deposited on a silicon substrate. We change the thickness of our samples using lithography and ion milling. We measure and analyze the thickness …

Electroproduction Of W Mesons Off Protons In The Third Resonance Region And Beyond, Evan Phelps

Theses and Dissertations

Exclusive electroproduction of ω(782) mesons in the reaction ep → epω → epπ+π−π0 was studied from the production threshold, through the third resonance region, and beyond. With electron beam energies close to 6 GeV, the kinematic range covers W = [1.72, 2.60) GeV and Q2 = [1.85, 5.15) GeV2. By combining two sets of data collected by the Thomas Jefferson National Accelerator Facility’s wide-acceptance spectrometer (CLAS), the largest set of resonance-region differential cross sections, d2σh dΩ∗ , for ω electroproduction have been produced. Response functions RT + LRL, RTT , and RTL were extracted to provide a view of how …

On Slowly Rotating Supercompact Schwarzschild Stars, Nelson Camilo Posada-Aguirre

Theses and Dissertations

In this Ph.D thesis, I will present results concerning to my doctoral research project submitted to the Department of Physics and Astronomy at the University of South Carolina. The thesis belongs to the area of Theoretical Physics, particularly, in the framework of Einstein’s Theory of General Relativity.

The project is the study of integral and surface properties of slowly rotating homogeneous masses in the gravastar limit R ! Rs, where Rs is the Schwarzschild radius. For this purpose we followed the perturbative method proposed by Hartle in 1967. In this model, the relativistic equations of structure for a slowly rotating …

Determination Of Polarization Transfer Coefficients And Hyperon Induced Polarization For Quasi–Free Hyperon Photoproduction Off The Bound Neutron, Colin Gleason

Theses and Dissertations

The spectrum of the excited nucleon (N*) states provides key information on the relevant degrees of freedom within the nucleon. The determination of the N* spectrum requires an extensive set of high–quality experimental observables for a large number of nuclear reactions over a broad kinematic range. In particular, measurements of polarization observables of strangeness photoproduction are of high importance as many of the resonances that are predicted by quark models, but not observed in pion– nucleon channels, are expected to couple strongly to kaon–hyperon (KY) channels. While in the last decade a large body of polarization and cross–section data has …

Polarization Observables In Double Pion Photo-Production With Circularly Polarized Photons Off Transversely Polarized Protons, Lelia Aneta Net

Theses and Dissertations

The study of excited states of the nucleon facilitates the understanding of the nucleon structure and its underlying symmetry and couplings. A main goal of the N^L program at the Thomas Jefferson National Accelerator Facility is to investigate the excitation and decays of the baryon resonances and assist in identifying the “missing” nucleon resonances that are predicted by theoretical models. One way to study the nucleon resonances is by extracting polarization observables, which provide more information than the unpolarized cross-section studies, e.g. access to the transition amplitudes of the reaction. Double-pion photoproduction contributes strongly to the total cross section …

Geometric Influence On Electronic Properties: Graphene With Antidots, Two-Dimensional Electron Gas And Three-Dimensional Carbon Nanostructures, Lei Wang

Theses and Dissertations

Geometric influence on electrical and magneto transport properties has been investigated in three types of systems: (i) Graphene, a single layer of carbon atoms; (ii) Two-dimensional electron gas (2DEG) in AlInN/GaN heterostructure; and (iii) 3D carbon nanostructures, a special type of three-dimensional materials with spherical voids. Due to unique structures and energy dispersion relations, these three systems demonstrate distinct physical properties.

AlInN is the newest and amongst the widest band gap semiconductors. The 2DEG in AlInN/GaN heterostucture displays long transport lifetime along with conventional behaviors, including Shubnikov-de Haas (SdH) oscillation and weak localization. From SdH oscillation, the effective mass of …

Polarization Observables T And F In The Yp -> Pi P Reaction, Hao Jiang

Theses and Dissertations

The theory that describes the interaction of quarks is Quantum Chromodynamics (QCD), but how quarks are bound inside a nucleon is not yet well understood. Pion photoproduction experiments reveal important information about the nucleon excited states and the dynamics of the quarks within it and thus provide a useful tool to study QCD. Detailed information about this reaction can be obtained in experiments that utilize polarized photon beams and polarized targets.

Pion photoproduction in the yp -> pi p reaction has been measured in the FROST experiment at the Thomas Jefferson National Accelerator Facility. In this experiment circularly polarized photons …

Temperature Dependent Transport Properties Of Chemical Vapor Deposition Graphene With Metal And Metal Hydride Surface Functionalization, Bochen Zhong

Theses and Dissertations

Graphene, a two-dimensional semi-conductor material containing carbon atoms tightly bonded together in a hexagonal structure, was first isolated by mechanical exfoliation in 2004. Over the past decade, it has drawn huge research interest due to its outstanding mechanical, thermal, and electrical properties. These unique properties of graphene lead to very high carrier mobility. In particular, after an annealing treatment to remove the residual impurities, the suspended graphene mobility exceeds 200,000 cm2/Vs. However, this value is highly reduced to only a few thousand cm2 /Vs in supported graphene on SiO2 or SiC substrates, due to different sources of scattering. For example, …

Measurement Of New Observables From The Π + Π - Electroproduction Off The Proton, Arjun Trivedi

Theses and Dissertations

Knowledge of the Universe as constructed by human beings, in order to tackle its complexity, can be thought to be organized at varying scales at which it is observed. Implicit in such an approach is the idea of a smooth evolution of knowledge between scales and, therefore, access to how Nature constructs the visible Universe beginning from its most fundamental constituents. New and, in a sense, fundamental phenomena may typically be emergent as the scale of observation changes. The study of the Strong Interaction, which is responsible for the construction of the bulk of the visible matter in the Universe …

Exclusive Π− Electroproduction Off The Neutron In Deuterium In The Resonance Region, Ye Tian

Theses and Dissertations

This dissertation focuses on extracting the exclusive γ∗n(p) → pπ-(p) reaction cross section from deuterium data. The existing γ∗n → pπ- event generator is modified to include the spectator (proton) information based on the CD-Bonn potential [28] to simulate the real data process. With this method, the exclusive quasi-free process is isolated successfully as demonstrated by the comparison of the spectator momentum distribution of the simulation with the missing momentum distribution of the data, and the kinematical final-state-interaction contribution factor RFSI is extracted directly from the data according to the ratio between the exclusive quasi-free and full cross sections. The …

Hadronic Lorentz Violation In Chiral Perturbation Theory, Rasha Kamand

Theses and Dissertations

The leading-order Lorentz-violating hadronic Lagrange densities are constructed using chiral perturbation theory. This is done for both pions and nucleons starting from a two-flavor quark-level Lagrangian that consists of dimension-four Lorentzviolation operators. The effective Lagrangians are first constructed in the absence of external fields. The formalism is then extended to include interactions with external fields. The presence of Lorentz violation modifies the transformation behavior of external fields under the chiral group SU(2)L × SU(2)R. This in turn leads to modified pion and nucleon covariant derivatives. By expanding parts of both mesonic and baryonic Lagragians in terms of physical pion and …

Measurements Of Electrostatic Double Layer Potentials With Atomic Force Microscopy, Jason Giamberardino

Theses and Dissertations

The aim of this thesis is to provide a thorough description of the development of theory and experiment pertaining to the electrostatic double layer (EDL) in aqueous electrolytic systems. The EDL is an important physical element of many systems and its behavior has been of interest to scientists for many decades. Because many areas of science and engineering move to test, build, and understand systems at smaller and smaller scales, this work focuses on nanoscopic experimental investigations of the EDL. In that vein, atomic force microscopy (AFM) will be introduced and discussed as a tool for making high spatial resolution …

Rare Event Searches With Cuore Style Teo2 Bolometers, Nicholas Ivan Chott

Theses and Dissertations

In this dissertation we report on the first search for solar axions from atomic transitions in the solar core. A search for the 14.4 keV axion from the ground state transition in 57Fe in the sun was also performed, via the axioelectric effect in TeO2 bolometers, in the CUORE-0 experiment. Both axion searches are performed in the scope of the DSFZ invisible axion model. An upper bound on the axion-electron coupling constant of gae ≤ 3.1 x 10^-11 (95% CL) is obtained with 62.7 kg days of TeO2 exposure from the CUORICINO experiment. The CUORE-0 data results in a …

Neutrino And Antineutrino Induced Meson Production, Libo Jiang

Theses and Dissertations

Coherent meson production measurement is very important in physics research. First, the coherent pion production is a potential background to v oscillation in next generation of Long Base Line Experiment(ELBNF/DUNE); second, coherent pion and coherent p production provide a detailed test of CVC and PCAC hypothesis; third, coherent meson production can be used to monitor the neutrino and anti-neutrino fluxes in the experiment. This dissertation focuses on two parts: coherent pi production in NOMAD, and coherent p simulation using LBNF fluxes. With the NOMAD data, the ratio between cross-sections of coherent pi- and v charged current interactions was measured and …