Physical Sciences and Mathematics Commons^™

Study Of The N = 77 Isotones Near The Proton-Drip Line; Isomeric Decays Of 140Eu, 142Tb, 144Ho, And 146Tm, Mohammed Noor Tantawy

Doctoral Dissertations

In this dissertation, the systematics of the [pi]h₁₁/₂ [tensor] [nu]h₁₁/₂ and [pi]h₁₁/₂ [tensor] [nu]s₁/₂ isomeric configurations were studied for the odd-Z, N = 77 isotones near the proton drip line. The isomeric decays in ¹⁴⁰Eu, ¹⁴²Tb, ¹⁴⁴Ho and ¹⁴⁶Tm were measured by means of X-ray, [gamma]-ray and charged particle spectroscopy at the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). The spin and parity of I[pi] = 8⁺ and 5⁻ were deduced for the isomers in ¹⁴⁰ Eu and ¹⁴²Tb. New decay schemes were established, and the half-lives of the 8⁺ …

Gravity In Extra Dimensions Of Infinite Volume, Chad Aaron Middleton

Doctoral Dissertations

In this thesis, we discuss various aspects of the Dvali-Gabadadze-Porrati (DGP) model in D-dimensions. Firstly, we generalize the DGP model, which consists of a delta-function type 3-brane embedded in an infinite volume bulk-space by allowing the 3-brane to have a finite thickness. We calculate the graviton propagator in the harmonic gauge both inside and outside the brane and discuss its dependence on the thickness of the brane. We obtain two infinite towers of massive modes and tachyonic ghosts. In the thin-brane limit, we recover the four-dimensional Einstein gravity behavior of the graviton propagator which was found in the delta-function treatment. …

The Ds/Cft Correspondence And Quasinormal Modes Of Black Holes, Scott Henry Ness

Doctoral Dissertations

In this thesis we discuss two aspects of quantum gravity and break it up in the following way. In part I, we discuss a scalar field theory living in de Sitter space-time. We may describe the infinite past or future as being boundaries of this space-time and, on these boundaries we construct a field theory. It has been shown by Strominger that there exists a correspondence between the bulk de Sitter space-time and the field theory living in the infinite past [1]. This may be described as a holographic principle, where information in the bulk de Sitter space-time corresponds to …

Ac Loss And Thickness Dependence Of Critical Currents In Coated Conductors, Anota Oluwatoyin Ijaduola

Doctoral Dissertations

This program of research is directed toward understanding the physical properties of certain materials in superconductive “coated conductors.” Specifically investigated were Ni1−xWx alloys for use as substrate and thin films of YBa 2Cu3O7, a high- Tc superconductor with many attractive features. A study has been conducted on the magnetic properties of a series of biaxially textured Ni1−xWx materials with compositions x = 0, 3, 5, 6, and 9 at.% W. These materials are important as substrates for “RABiTS”-type coated conductors that incorporate high temperature superconductors for current transport. The quasi-static dc and ac …

Photo-Acoustic Analysis Of Dental Materials And Tissue, Pavlina Jetchkova Jeleva

Doctoral Dissertations

The goal of the presented study is the investigation of the feasibility of using optically generated acoustic waves for analysis of dental material below laser-ablation threshold.

The temperature rise of dental material and tissue has been modeled analytically and numerically, and measured experimentally. Following interactions with nano- and femto-second laser radiation the temperature rises at a rate of typically 1 ±C per J=cm2, along with the generation of an acoustical wave. The results from the models agree with the experiment. The acoustic measurements show differences in the acoustic signal strength and the frequency spectrum when the canal in the …

Shell Model Monte Carlo Method In The Pn-Formalism, Cem Ozen

Doctoral Dissertations

We report on the development of a new shell-model Monte Carlo algorithm, which uses the proton-neutron formalism. Shell model Monte Carlo methods, within the isospin formulation, have been successfully used in large-scale shell-model calculations. Motivation for this work is to extend the feasibility of these methods to shell model studies involving non-identical proton and neutron valence spaces. We show the viability of the new approach with some test results. Finally, we use a realistic effective nucleon-nucleon interaction in the model space described by (1p_1/2, 0g_9/2) proton and (1d_5/2, 2s_{1/2 …}

Neutron Scattering Studies On Magnetism And Phonon In The Electron-Doped Nd2-Xcexcuo4 And Pr1-Xlacexcuo4, Hye Jung Kang

Doctoral Dissertations

We present comprehensive neutron scattering studies on the electron-doped superconductors Nd_2-xCe_xCuO₄ and Pr_1-xLaCe_xCuO₄ to understand how magnetic properties and phonon are related to superconductivity. For the superconducting Nd_1.85Ce_0.15CuO₄, a c-axis magnetic field enhances the commensurate antiferromagnetic order, while an ab-plane magnetic field induces spin-flop transition from the noncollinear to the collinear magnetic structure. The c-axis field-induced effect is absent in both the parent Nd₂CuO₄ and the as-grown nonsuperconducting Nd_1.85Ce_0.15CuO₄ samples. These results, combined …

Developing A B -Tagging Algorithm Using Soft Muons At Level-3 For The Dø Detector At Fermilab, Mayukh Das

Doctoral Dissertations

The current data-taking phase of the DØ detector at Fermilab, called Run II, is designed to aid the search for the Higgs Boson. The neutral Higgs is postulated to have a mass of 117 GeV. One of the channels promising the presence of this hypothetical particle is through the decay of b-quark into a muon. The process of identifying a b-quark in a jet using muon as a reference is b-tagging with a muon tag.

At the current data taking and analysis rate, it will take long to reach the process of identifying valid events. The triggering mechanism of the …