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Data analysis for space-based gravitational wave detectors: Author: Crowder, Jefferson Osborn; Date: 2006-05-15; Program: Physics; Abstract: With the launch of the Laser Interferometer Space Antenna (LISA) expected for the next decade, the nascent field of gravitational wave astronomy will be taking a giant leap forward. The data that will be gathered from space-borne gravitational wave detectors such as LISA will provide an expansive look through a new window on the Universe. This dissertation is presented to help open that window by exploring some of the techniques and methods that will be needed to understand the data from these detectors. The first original work presented here investigates the resolution of LISA and follow-on s...; Download File | View full details

Energies of rare-earth ion states relative to host bands in optical materials from electron photoemission spectroscopy: Author: Thiel, Charles Warren; Date: 2003-12-15; Program: Physics; Abstract: There are a vast number of applications for rare-earth-activated materials and much of today's cutting-edge optical technology and emerging innovations are enabled by their unique properties. In many of these applications, interactions between the rare-earth ion and the host material's electronic states can enhance or inhibit performance and provide mechanisms for manipulating the optical properties. Continued advances in these technologies require knowledge of the relative energies of rare-earth and crystal band states so that properties of available materials may be fully understood and new ...; Download File | View full details

Ferromagnetism in cobalt-doped titanium dioxide: Author: Lussier, Alexandre Francois; Date: 2005-12-15; Program: Physics; Abstract: Semiconductor spintronics is a promising new field of study in the ongoing quest to make electronic devices faster, cheaper, and more efficient. While current spintronics utilizes the spin property of electrons to achieve greater functionality, the integration of spintronics into conventional semiconductor electronics will lead to advances in opto-electronics, quantum computing, and other emerging fields of technology. This integration relies on effective generation, injection, transport, and detection of spin polarized electron currents. To these ends, the successful synthesis of room tempera...; Download File | View full details

Gravitational wave astronomy using spaceborne detectors: Author: Rubbo, Louis Joseph; Date: 2004-08-15; Program: Physics; Abstract: This dissertation explores the use of spaceborne gravitational wave detectors as observatories for studying sources of gravitational radiation. The next decade will see the launch of the first space-based gravitational wave detector. Planning for several follow on missions is already underway. Before these observatories are constructed, extensive studies into their responses, expected output, and data analysis techniques must be completed. In this dissertation these issues are addressed using the proposed Laser Interferometer Space Antenna as an exemplary model. The first original work present...; Download File | View full details

Magnetohydrodynamic shocks near rotating black holes: Author: Rilett, Darrell Jon; Date: 2003-08-15; Program: Physics; Abstract: The theory of general relativistic magnetohydrodynamic standing shock formation is analyzed for accreting MHD plasma in a rotating, stationary, and axisymmetric black hole magnetosphere. All postshock physical quantities are expressed in terms of the relativistic compression ratio. The compression ratio is a solution of a seventh degree polynomial, incorporating the jump conditions, that is to be solved simultaneously with an equation for the polytropic index of the postshock plasma. Then the downstream state of the shocked plasma is determined entirely in terms of preshock quantities. Slow an...; Download File | View full details

Modeling Piezoelectric PVDF Sheets with Conductive Polymer Electrodes: Author: Lediaev, Laura Marie; Date: 2006-05-15; Program: Physics; Abstract: The main concern of my research has been to find a good way to solve for the behavior of piezoelectric devices that are electroded not with metal electrodes (as has traditionally been the case) but with a conductive polymer material which has a much lower conductivity compared to metal. In this situation, if a time-varying voltage is applied at one end of the electrode, the voltage cannot be assumed to be uniform throughout the electrode because of the effects of resistivity. Determining the voltage in the electrodes as a function of time and position concurrently with the mechanical and elect...; Download File | View full details

Relativistic Accretion Flows onto Supermassive Black Holes: Shock Formation and Iron Fluorescent Emission Lines in Active Galactic Nuclei: Author: Fukumura, Keigo; Date: 2005-05-15; Program: Physics; Abstract: One of the exciting discoveries from the recent X-ray spectroscopic studies of active galactic nuclei (AGNs) is the so called "relativistically-broadened iron fluorescent emission line" often detected in the hard X-ray spectra. It is generally believed to originate from the inner part of the accretion disk surrounding a supermassive black hole (BH) at the center. Although we have begun to obtain some physical insight regarding such emission lines supported by theoretical models (e.g., disk-corona model), exactly how and where the observed fluorescence may take place is still disputab...; Download File | View full details

Search for Point-Like Sources of Cosmic Rays with Energies Above 10 (18.5) eV in the Hires-I Monocular Dataset: Author: Kirn, Malina Aurelia; Date: 2005-05-15; Program: Physics; Abstract: We report the results of a search for pointlike deviations from isotropy in the arrival directions of ultra-high energy cosmic rays in the northern hemisphere, carried out using a skymap technique. In the monocular dataset collected by the High-Resolution Fly's Eye, consisting of 1,525 events with energy exceeding 10(18.5) eV, we find no evidence for pointlike excesses. Pointlike excesses at these energies can arise from only a limited number of source scenarios. Galactic and extragalactic magnetic fields are expected to produce large perturbations in the arrival directions of charged particle...; Download File | View full details

Simultaneous Two-Photon Absorption of Tetrapyrrolic Molecules: From Femtosecond Coherence Experiments to Photodynamic Therapy: Author: Karotki, Aliaksandr; Date: 2003-12-15; Program: Physics; Abstract: Simultaneous two-photon absorption (TPA) in tetrapyrrolic molecules is studied and its applications to two-photon coherence gratings and singlet oxygen generation for photodynamic therapy are demonstrated in this thesis. First ever comprehensive study of TPA properties of tetrapyrrolic molecules is conducted in this work. Two-photon transitions in two key spectral regions, red to green and blue to near-UV (transition wavelengths) are investigated. Physical mechanisms leading to enhancement of TPA cross section in tetrapyrroles are elucidated. Porphyrin molecules with greatly enhanced two-photo...; Download File | View full details

Size Dependence of the Magnetic Properties of Cobalt Oxide Nanoparticles Mineralized in Protein Cages: Author: Resnick, Damon Aaron; Date: 2005-12-15; Program: Physics; Abstract: A major question in the Physics of magnetic nanoparticles is how the size affects the magnetic properties in magnetic nanoparticle systems. In particular, the magnetic properties can be affected by finite-size effects or surface effects. It is this author's belief that surface effects and not finite-size effects play the dominate role. This study is a specific example of how to try to answer this question by looking at different sizes of Co₃O₄ nanoparticles. In order to answer this question as well as better understand this system, different antiferromagnetic Co₃Oâ...; Download File | View full details

The Solar Extreme Ultra-Violet Corona: Resolved Loops and the Unresolved Active Region Corona: Author: Cirtain, Jonathan Wesley; Date: 2005-05-15; Program: Physics; Abstract: In this work, physical characteristics of the solar corona as observed in the Extreme Ultra-Violet (EUV) regime are investigated. The focus will be the regions of intense EUV radiation generally found near the locations of sunspots. These regions are commonly called active regions. Multiple space-based observing platforms have been deployed in the last decade; it is possible to use several of these observatories in combination to develop a more complete picture of the solar corona. Joint Observing Program 146 was created to collect spectroscopic intensities using the Coronal Diagnostic Spectro...; Download File | View full details

Water vapor profiling using a widely tunable amplified diode laser Differential Absorption Lidar (DIAL): Author: Obland, Michael Drew; Date: 2007-05-15; Program: Physics; Abstract: Water vapor is one of he most significant constituents of the atmosphere because of its role in cloud formation, precipitation, and interactions with electromagnetic radiation, especially its absorption of longwave infrared radiation. Some details of the role of water and related feedback mechanisms in the Earth system need to be characterized better if local weather, global climate, and the water cycle are to be understood. Water vapor profiles are currently obtained with several remote sensing techniques, such as microwave radiometers, passive instruments like the Atmospheric Emitted Radianc...; Download File | View full details

Quantitative studies of terrestrial plasmaspheric dynamics enabled by the IMAGE spacecraft: Author: Larsen, Brian Arthur; Date: 2007-05-15; Program: Physics; Abstract: Terrestrial plasmaspheric dynamics have been observed using single satellite passes and long term statistical studies for many years all with in-situ measurements. The EUV instrument aboard the IMAGE spacecraft provided global plasmaspheric data by imaging He-II at 30.4nm. The global imaging revealed significant dynamics modifying current theory and observing many new features. Global imaging removes any space/time ambiguity and provides a regular high-quality data set ideal for correlative studies and region comparisons. This work presents several studies enabled by this global imaging: an em...; Download File | View full details

The topology of magnetic reconnection in solar flares: Author: Des Jardins, Angela Colman; Date: 2007-08-15; Program: Physics; Abstract: In order to better understand the location and evolution of magnetic reconnection, which is thought to be the energy release mechanism in solar flares, I combine the analysis of hard X-ray (HXR) sources observed by RHESSI with a three-dimensional, quantitative magnetic charge topology (MCT) model. I first examine the evolution of reconnection by analyzing the relationship between observed HXR footpoint motions and a topological feature called spine lines. With a high degree of confidence, I find that the HXR footpoints sources moved along the spine lines. The standard two dimensional flare mod...; Download File | View full details

Mode-Locked Ramam Laser in H2 Pumped by a Mode-Locked External Cavity Diode Laser: Author: Xiong, Yihan; Date: 2007-08-15; Program: Physics; Abstract: In this thesis, a theory is first presented for a far-off resonance mode-locked Raman laser in H2 with high finesse cavity enhancement. The theoretical derivation for the mode-locked Raman laser is based on semiclasscial laser theory and time-dependent continuous wave (CW) Raman theory. Numerically calculated results, including the intracavity fields' amplitude and phase evolution and output Stokes power versus input pump power are discussed in three different regimes depending on the relationship between the coherence dephasing rate and the repetition rate of the mode-locked pump laser. Then...; Download File | View full details

Applications of quantum field theory in curved spacetimes: Author: Calderon, Hector Hugo; Date: 2007-12-15; Program: Physics; Abstract: While there is as yet no full theory of Quantum Gravity, some computations can still be performed in the regime where both gravitational and quantum effects are appreciable. These types of calculations, all of them perturbations, are performed in the hope they would provide guidance for the development of the full theory. This dissertation presents work related to three calculations using Quantum Field Theory in Curved Spacetimes. Primarily, the stress energy tensor of vacuum states is computed near Big Rip singularities, sudden singularities and in presence of a Schwarzschild-(anti) de Sitter...; Download File | View full details

Precession Damping in Itinerant Ferromagnets: Author: Gilmore, Keith; Date: 2007-12-15; Program: Physics; Abstract: Precession damping in metallic ferromagnets had been assumed to result from the spinorbit interaction. While several theories of spin-orbit damping had been postulated, no convincing numerical comparisons to data existed. We selected one promising theory and performed first-principles numerical calculations of damping for bulk iron, cobalt, and nickel. Comparison of minimal calculated and measured damping rates demonstrated a 70 % agreement for nickel, 60 % for iron, and 40 % for cobalt. We then relaxed the initial constraint of a universal electron-lattice scattering rate by allowing the scat...; Download File | View full details

X-ray characterization of buried layers and interfaces in EuO based spin-filter tunnel junctions: Author: Negusse, Ezana; Date: 2008-05-15; Program: Physics; Abstract: Spin filtering tunnel junctions provide a convenient method for controlling and manipulating the spin of electrons in spintronic devices. In a tunnel junction, the tunneling current depends exponentially on the thickness of the tunneling barrier. Ultrathin (~20 angstroms) barriers are highly desirable because they lower the junction resistance. In addition to the barrier thickness, the spin filtering efficiency of the junction depends on the tunneling barrier's magnetic properties and the nature of the barrier-electrode interfaces. EuO's high TC (69 K) and large exchange splitting (2 �...; Download File | View full details

Thulium ions in a yttrium aluminum garnet host for quantum computing applications: material analysis and single qubit operations: Author: Zafarullah, Ijaz; Date: 2008-05-15; Program: Physics; Abstract: Rare-earth-doped crystals have been used for optical signal processing and storage applications. In this dissertation, their potential for quantum computing applications is explored. In one quantum computing scheme, information is stored in nuclear spin states and this information is then processed by using optical pulses through the coupling of these nuclear spin states to a common electronic level. To implement this scheme, nuclear spin states and coupling of these nuclear spin states to a common electronic level is required. Preliminary work in rare-earth materials like Pr3+ and Eu3+ has sh...; Download File | View full details

Anti-Stokes generation in a continuous wave raman laser: Author: Murphy, Sytil Kathleen; Date: 2008-08-15; Program: Physics; Abstract: The continuous-wave Raman laser system differs from other Raman systems in that it uses cavity enhancement to augment the pump laser source rather than a high-power pulsed laser source. Through interactions of the pump laser with the Raman active medium, all Raman systems can produce both red-shifted, Stokes, emission and blue-shifted, anti-Stokes, emission. Previous, continuous-wave Raman laser systems have focused on the Stokes emission. This dissertation presents theory and data on the anti-Stokes emission. Specifically, it investigates the anti-Stokes mode structure and the emitted power a...; Download File | View full details

An investigation into student understanding of longitudinal standing waves: Author: Dostal, Jack Alan; Date: 2009-05-15; Program: Physics; Abstract: This study investigates the difficulties that introductory university Physics students have with the concept of longitudinal standing waves in the context of standing waves in pipes. My goal is to identify difficulties that persist even after standard instruction on longitudinal standing waves and attempt to improve upon that method of instruction. The study follows a four-step design. I first use exploratory surveys and interviews with students to elicit the difficulties present in students' understanding of longitudinal standing waves in pipes. I then use the information gained to create and...; Download File | View full details

A comprehensive Bayesian approach to gravitational wave astronomy: Author: Littenberg, Tyson Bailey; Date: 2009-05-15; Program: Physics; Abstract: The challenge of determining whether data from a gravitational wave detector contains signals which are cosmic in origin is the central problem in gravitational wave astronomy. The "detection problem" is particularly challenging for low amplitude signals embedded in "glitchy" instrument noise. It is imperative that we can robustly distinguish between the data being consistent with instrument noise alone, or noise and a weak gravitational wave signal. In response to this challenge we have set out to develop a robust, general purpose approach that can locate and characterize ...; Download File | View full details

Building a Raman laser pump source capable of generating flexible pulse durations while maintaining high spatial quality: Author: Wagemann, Stephen Scott; Date: 2009-05-15; Program: Physics; Abstract: A detailed characterization of a Raman pump laser throughout the construction process is reported. Due to specific requirements for the pulsed Raman experiment, there were no commercially available pump lasers capable of meeting our specifications. The pump source must produce high energy pulses of 50mJ to 100mJ with variable duration centered at 200ns. To create this pump source, the pulses are gated from a CW source and then amplified with a high gain Nd:YAG amplification system. High spatial quality is also a necessity as the laser needs to be coupled into a small diameter waveguide functio...; Download File | View full details

Combining hydrodynamic modeling with nonthermal test particle tracking to improve flare simulations: Author: Winter, Henry deGraffenried III; Date: 2009-05-15; Program: Physics; Abstract: Solar flares remain a subject of intense study in the solar Physics community. These huge releases of energy on the Sun have direct consequences for humans on Earth and in space. The processes that impart tremendous amounts of energy are not well understood. In order to test theoretical models of flare formation and evolution, state of the art, numerical codes must be created that can accurately simulate the wide range of electromagnetic radiation emitted by flares. A direct comparison of simulated radiation to increasingly detailed observations will allow scientists to test the validity of th...; Download File | View full details

An investigation into the effects of completion problems on the performance of introductory Physics students: Author: Wolf, Jeremy Tyler; Date: 2009-08-15; Program: Physics; Abstract: In this study the completion problems were voluntary. I believe it has been reasonably shown that the completion problems do not have a negative effect on test performance. If the act of completing a completion problem is useful making the completion problems mandatory would seem to be a simple improvement that may result in further or more widespread gains. Further, I believe that completion problems are realistic to implement for an entire semester or year-long course, in terms of time invested in creation of the problems compared to the possible gains made by students. The study has also sh...; Download File | View full details

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