Digital Commons Network^™

Implementation Of The Clas12 Htcc Into Gemc, Nathan A. Harrison

Master's Theses

No abstract provided.

Photoionization Of The Potassium Isoelectronic Sequence: Ca+ And Transition Metal Ions, Ayao M. Sossah

Physics and Astronomy Dissertations

Photoionization cross section calculations are performed for the ground ([Ne]3s23p63d 2D ) and the first two excited ([Ne]3s23p63d 2D and [Ne]3s23p64s 2S ) states of potassium-like transition metal ions (Sc+2, Ti+3, V+4, Cr+5, Mn+6, Fe+7), along with photoionization calculations for K-like Ca+ ions in the ground ([Ne]3s23p64s 2S ) state and the first two excited ([Ne]3s23p63d 2D and [Ne]3s23p63d 2D ) states. The discrete N-electron final state ion system orbitals are generated using the computer program AUTOSTRUCTURE; 24 configurations are included in the configuration-interaction (CI) calculation for transition metal ions, and 30 configurations for the case of Ca+ ions. The …

Scattering Matrix Elements For The Nonadiabatic Collision B (2PJₐ) + H2 (1Σ+G, Ν, Ј) ↔ B (2PJ’ₐ) + H2 (1Σ+G, Ν’, J’)., Luke A. Barger

Theses and Dissertations

Scattering matrix elements are calculated for the nonadiabatic inelastic collision B (²P_jₐ) + H₂ (¹Σ⁺_g, ν, ј) ↔ B (²P_j’ₐ) + H₂ (¹Σ⁺_g, ν’, j’). This calculation utilizes the effective potential energy surfaces for this collision generated by Garvin along with a correction to the asymptotic H₂ potential. Wavepackets are propagated on these surfaces using a split-operator propagator. This propagation yields correlation functions between reactant and product Møller states which are used to calculate the scattering …

Tunable Optical Delay In Doppler-Broadened Cesium Vapor, Monte D. Anderson

Theses and Dissertations

Variable-delay tunable optical delay line or optical buffers are critical for the development of all-optical networks components as well as interferometry and analytic instruments. Recent research on slow light may hold the key for the development of the first practical tunable optical delay device. In this research the linear dispersion delay effects in an alkali vapor. The hyperfine relaxation observations present insight into the complex bleach wave dynamics during a high-intensity pulsed pump in DPAL systems.

Microvariability Of The Blazar 3c279, Hannah M. Clemmons

Physics and Astronomy Theses

Active Galactic Nuclei (AGN) are some of the most extreme objects in the universe. They output copious amounts of energy spanning the entire electromagnetic spectrum. There are many different subclasses of AGN depending on your viewing angle. Blazars, viewing down the relativistic jet, are the most variable class of AGN known. They exhibit extreme variability in all wavelengths on timescales as short as minutes. In this thesis I will consider the extreme faintness of 3C279 with respect to the long-term light curve as well as recent observations of microvariability. I am able to confirm small amplitude events using simultaneous observations …

Spin-Lattice Coupling In The Iron-Pnictide High-Temperature Superconductors, Daniel E Parshall

Doctoral Dissertations

The recent discovery of the iron-pnictide superconductors has generated tremendous excitement, in part because there are many tantalizing similarities to the cuprate superconductors. As with the cuprates, it is strongly suspected that the spins contribute to superconductivity.

There seems to be a strong relationship between the lattice and magnetism in this system. Several authors have discussed the possibility of spin-phonon coupling, but direct experimental evidence has remained elusive.

This work discusses the relationship between the spins and the lattice in the $BaFe_{2}As_{2}$ family. We demonstrate the presence of negative thermal expansion in these materials, which is a strong indicator of …

Could Alice Find The Elusive Higgs?, Tyler Williams

Physics

The Higgs boson is the theoretical mechanism for creating the mass of particles. Although it has never been seen, the CERN Large Hadron Collider (LHC) is the most likely place for it to be created in the laboratory. The ALICE (A Large Ion Collider Experiment) detector is focused on the study of heavy ion collisions at the LHC and was not designed to find the Higgs boson; however, there is a chance it could be detected there. Although the luminosity (collision rate) for PbPb collisions is much lower than that for pp collisions, PbPb collisions have a higher probability to …

Measurement System For High Pressure Characterizations Of Materials, Matthew K. Jacobsen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Thermoelectric materials have long been investigated for possible use as power sources. This application was recently put to use in the Voyager space program, powering the deep space probes. Despite the usefulness of these materials, the use of pressure to investigate the material properties has only recently become interesting. As such, the work in this document was to developing a system for concurrently measuring the necessary properties. This system is capable of measuring the electrical resistivity, thermal conductivity, and Seebeck coefficient in the pressure range from 0 - 10 GPa. The results for zinc, almandine garnet, and nickel are presented …

Speciation And Spectroscopy Of The Uranyl And Tetravalent Plutonium Nitrate Systems: Fundamental Studies And Applications To Used Fuel Reprocessing, Nicholas A. Smith

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation explores the use of UV-Visible spectroscopy and Time Resolved Laser Induced Fluorescence spectroscopy as near real time process monitors of uranium and plutonium concentrations in aqueous reprocessing trains. The molar absorptivities and linear ranges of these metals were investigated under total nitrate and acid concentrations similar to those found in current reprocessing systems. Concurrent to this, a new multiple wavelength monitor was derived that is capable of determining the total nitrate concentration spectroscopically. This method uses the uranium absorbance spectrum to calculate the nitrate concentration in solution. When used as part of an Advanced Safeguard suite, this technique …

Chemical And Electronic Structure Of Surfaces And Interfaces In Compound Semiconductors, Sujitra Pookpanratana

UNLV Theses, Dissertations, Professional Papers, and Capstones

The interface formation between two different materials is important in applications for optoelectronic devices. Often, the success or performance of these devices is dependent on the formation of these heterojunctions. In this work, the surface and interfaces in such materials for optoelectronic devices are investigated by a suite of X-ray analytical techniques including X-ray photoelectron (XPS), X-ray excited Auger electron (XAES), and X-ray emission (XES) spectroscopies to provide novel insight.

For the group III-nitrides (e.g., AlxGa1-xN) used in many light emitting devices, a significant challenge exists to form an Ohmic contact. The electron affinities and band gaps of GaN and …

Liquid Helium Refill Shifts At The Cryogenic Underground Observatory For Rare Events, Robin L. Reil

Physics

No abstract provided.

Dielectronic Recombination For Aluminum-Like Ions And Photoabsorption Cross Sections For Magnesium Ions At The K-Edge, Shahin Ahmed Abdel-Azim Abdel Naby

Dissertations

Accurate and reliable recombination data are needed for modeling the ions in the finitedensity plasmas that may take place in solar flares and in divertors of magnetically confined fusion devices such as the International Thermonuclear Experimental Reactor (ITER). Dielectronic recombination (DR) is the dominant recombination mechanism in photoionized and collisionally-ionized plasmas. DR rate coefficients for M-shell argon ions have been calculated using a configuration-average approach. DR rate coefficients for the aluminumlike isoelectronic sequence are instead calculated using the state-of-the-art multiconfiguration Breit-Pauli (MCBP) atomic structure and collision code AUTOSTRUCTURE. Good agreement is obtained with the measurements from the Heidelberg heavy-ion Test …

A System For Measuring Radiation Induced Chemical Products In Atmospheric Gases Using Optical Detection Methods, Tyler Webster Reese

Master's Theses

This research is a part of an effort to characterize the chemical products generated by radiation interacting with atmosphere. One method of detecting ionizing radiation is to monitor the radiation induced products in the atmosphere around the source. This project explored the potential for using Cavity Ringdown Spectroscopy to evaluate the presence of chemical products generated by the air-radiation interaction near an alpha radiation source. In particular, measurements of ozone concentration within a controlled atmosphere chamber as affected by radiation exposure were obtained.

The first portion of this thesis provides brief reviews of ionizing radiation and ozone formation as well …

Statistical Analysis Of The Usu Lidar Data Set With Reference To Mesospheric Solar Response And Cooling Rate Calculation, With Analysis Of Statistical Issues Affecting The Regression Coefficients, Troy Alden Wynn

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Though the least squares technique has many advantages, its possible limitations as applied in the atmospheric sciences have not yet been fully explored in the literature. The assumption that the atmosphere responds either in phase or out of phase to the solar input is ubiquitous. However, our analysis found this assumption to be incorrect. If not properly addressed, the possible consequences are bias in the linear trend coefficient and attenuation of the solar response coefficient.

Using USU Rayleigh lidar temperature data, we found a significant phase offset to the solar input in the temperatures that varies ±5 years depending on …

Comparison Of H-Alpha And H-Beta Temperature Indices In The Hyades And Coma Star Clusters And Selected H-Beta Standard Stars, Miriam Anne West

Theses and Dissertations

Using the Dominion Astrophysical Observatory's 1.2-m McKellar Telescope, we have obtained spectra on 81 stars from the Hyades Cluster, the Coma Cluster, and selected H-beta standard stars. These spectra cover from 4500 Å to 6900 Å which includes both the H-β and H-α absorption lines. The H-β absorption line has a long history of being used as a temperature index and more recently, calibration of an H-α index has been established for photometric observations. Through spectrophotometric comparison of temperature indices from the H-α and H-β absorption lines we find the expected strong correlation between photometric indices based on the strength …

Inner-Shell Photodetachment Of Transition Metal Negative Ions, Ileana Dumitriu

Dissertations

This thesis focuses on the study of inner-shell photodetachment of transition metal negative ions, specifically Fe¯ and Ru¯. Experimental investigations have been performed with the aim of gaining new insights into the physics of negative atomic ions and providing valuable absolute cross section data for astrophysics. The experiments were performed using the X-ray radiation from the Advanced Light Source, Lawrence Berkeley National Laboratory, and the merged-beam technique for photoion spectroscopy.

Negative ions are a special class of atomic systems very different from neutral atoms and positive ions. The fundamental physics of the interaction of transition metal negative ions with photons …

Proton Capture Reactions And Network Calculations On 46Ti, 64Zn, 114Sn And 116Sn Relevant To The Rp-Process, Ravin S. T. Kodikara

Dissertations

The rp-process makes an important contribution to the stellar nucleosynthesis by producing many of the light proton rich nuclei. Successive proton captures on seed nuclei followed by occasional β-decays and electron captures are the key features of this mechanism. For a detailed rp-process analysis, proton capture cross sections and reaction rates are essential. However, the lack of experimental data forces the researcher to largely depend on statistical model predictions.

This dissertation research is an attempt to investigate the proton captures of four particular nuclides; ⁴⁶Ti, ⁶⁴Zn, ¹¹⁴Sn and ¹¹⁶Sn. At Western Michigan University Van de Graaff …

Spatial Light Dilution As A Technique For Conversion Of Solar Energy To Algal Biomass, Daniel J. Dye

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A photobioreactor has been designed and developed to efficiently utilize solar irradiance through spatial dilution of sunlight. The concept of spatial light dilution is simple: incident sunlight is spread over a large surface area, thus reducing the photon flux density of the light. The implementation of this technique, however, is difficult. The reactor described within uses a new approach to spatial light dilution, utilizing recently-developed optical components to diffuse concentrated sunlight inside an algae culture. Preliminary productivity tests indicate a 2-3 fold increase in productivity per unit aperture (sunlight collection area) over a control reactor with direct-sunlight. Aperture productivity of …

Analytical Computation Of Proper Orthogonal Decomposition Modes And N-Width Approximations For The Heat Equation With Boundary Control, Tasha N. Fernandez

Masters Theses

Model reduction is a powerful and ubiquitous tool used to reduce the complexity of a dynamical system while preserving the input-output behavior. It has been applied throughout many different disciplines, including controls, fluid and structural dynamics. Model reduction via proper orthogonal decomposition (POD) is utilized for of control of partial differential equations. In this thesis, the analytical expressions of POD modes are derived for the heat equation. The autocorrelation function of the latter is viewed as the kernel of a self adjoint compact operator, and the POD modes and corresponding eigenvalues are computed by solving homogeneous integral equations of the …

New Tools For Monitoring Gamma Camera Uniformity, Brad K. Lofton

Dissertations & Theses (Open Access)

Detector uniformity is a fundamental performance characteristic of all modern gamma camera systems, and ensuring a stable, uniform detector response is critical for maintaining clinical images that are free of artifact. For these reasons, the assessment of detector uniformity is one of the most common activities associated with a successful clinical quality assurance program in gamma camera imaging. The evaluation of this parameter, however, is often unclear because it is highly dependent upon acquisition conditions, reviewer expertise, and the application of somewhat arbitrary limits that do not characterize the spatial location of the non-uniformities. Furthermore, as the goal of any …

Libs And Lite Emission Based Laser Remote Sensing Of Chemical Species And Enhanced Modeling Of Atmospheric Absorption, Dzianis V. Pliutau

USF Tampa Graduate Theses and Dissertations

Laser-Induced Breakdown spectroscopy (LIBS) and Laser-Induced Thermal Emission (LITE) emission based laser remote sensing were investigated with the application to the remote measurements of trace chemical species. In particular, UVvisible LIBS and Mid-IR LITE systems were developed and measurements of remote targets and chemical surfaces were studied. The propagation through the atmosphere of the multi-wavelength backscattered LIBS and LITE optical spectrum with atmospheric absorption effects on the returned lidar signal was investigated. An enhanced model of the atmospheric effects on emission-based laser-remote sensing was developed and found to be consistent and in agreement with our experimental results.

LITE measurements were …

Optical Design Of Beam Shaping Optics For Camera Probe And Led Light Illumination Used For Minimally Invasive Abdominal Surgery, Weiyi He

USF Tampa Graduate Theses and Dissertations

The optical design of a LED illuminator and camera imaging system were studied for potential use in a small medical "robotic type" probe to be used for minimally invasive abdominal surgery. Beam shaping optical reflectors were studied to increase the intensity distribution of the LED beam directed toward a close-by target surface. A CMOS/CCD camera and lens was used to image the targeted area. In addition, extensive optical ray tracing simulations were made to predict the intensity patterns. The experimental measurements and ray tracing simulations were in good agreement, and indicated that 20 degree cone reflectors for the LED sources …

Construction And Improvement Of A Scheffler Reflector And Thermal Storage Device, Jason Rapp

Physics

We constructed and successfully tested a 2 m2 parabolic dish solar concentrator (Scheffler Concentrator) to focus sunlight onto a stationary target. Present efforts are to decrease the construction complexity and cost of the concentrator. In order to store solar heat, we also constructed and are testing a thermal storage device made of sand (for thermal mass), and pumice (for insulation). Preliminary tests indicate thermal retention times of many hours. Present efforts are to increase accessible power, and structural integrity.

Generalized Acoustic Energy Density And Its Applications, Buye Xu

Theses and Dissertations

The properties of acoustic kinetic energy density and total energy density of sound fields in lightly damped enclosures have been explored thoroughly in the literature. Their increased spatial uniformity makes them more favorable measurement quantities for various applications than acoustic potential energy density (or squared pressure), which is most often used. In this dissertation, a new acoustic energy quantity, the generalized acoustic energy density (GED), will be introduced. It is defined by introducing weighting factors, α and 1 − α, in the formulation of total acoustic energy density. With the additional degree of freedom, the GED can conform to the …

Collisional Dynamics Of The Cesium D1 And D2 Transitions, Greg A. Pitz

Theses and Dissertations

The collisional dynamics of the 6²P levels in cesium have been studied utilizing steady state laser absorption and laser induced florescence techniques. In addition the production of a blue beam produced by two photon absorption has been observed in potassium. The collisional broadening rate for cesium, λ_L, for He, Ne, Ar, Kr, Xe, N₂, H₂, HD, D₂, CH₄, C₂H₆, CF₄, and ³He are 24.13, 10.85, 18.31, 17.82, 19.74, 16.64, 20.81, 20.06, 18.04, 29.00, 26.70, 18.84, and 26.00 MHz/torr, respectively for the …

Laser Demonstration And Performance Characterization Of An Optically Pumped Alkali Laser System, Clifford V. Sulham

Theses and Dissertations

Diode Pumped Alkali Lasers (DPALs) offer a promising approach for high power lasers in military applications that will not suffer from the long logistical trails of chemical lasers or the thermal management issues of diode pumped solid state lasers. This research focuses on characterizing a DPAL-type system to gain a better understanding of using this type of laser as a directed energy weapon. A rubidium laser operating at 795 nm is optically pumped by a pulsed titanium sapphire laser to investigate the dynamics of DPALs at pump intensities between 1.3 and 45 kW/cm². Linear scaling as high as …

Frontiers In Theoretical High Energy Physics: From Physics Beyond The Standard Model To Cosmology, Mohamed M. Anber

Open Access Dissertations

This dissertation is focused on three lines of work. In the first part, we consider aspects of holography and gauge/gravity duality in lower and higher dimensions. In particular, we study the duality for exact solutions localized on the Randal-Sundrum 2-branes. We also test if some holographic principles in general relativity can be generalized to include higher derivative theories of gravity; namely Lovelock gravity. In the second part we consider the role of pseudo Nambu-Goldstone bosons (pNGBs) in inflationary cosmology. Specifically, we construct an inflationary model using string theory axions, and use these pNGBs to produce the observed coherent magnetic field …

Self-Assembly Of Nanoparticles At Liquid-Liquid Interfaces, Kan Du

Open Access Dissertations

In this thesis, we studied the self-assembly of nanoparticles at liquid metal-water interfaces and oil-water interfaces. We demonstrated a simple approach to form nanostructured electronic devices by self-assembly of nanoparticles at liquid metal surfaces. In this approach, two liquid-metal droplets, which were coated with a monolayer of ligand-stabilized nanoparticles, were brought into contact. They did not coalesce but instead remained separated by the nanoparticles assembled at the interface. Devices formed by this method showed electron transport between droplets that was characteristic of the Coulomb blockade, where current was suppressed below a tunable threshold voltage because of the energy of charging …

Characterization And Interactions Of Ultrafast Surface Plasmon Pulses, Sibel Ebru Yalcin

Open Access Dissertations

Surface Plasmon Polaritons (SPPs) are considered to be attractive components for plasmonics and nanophotonic devices due to their sensitivity to interface changes, and their ability to guide and confine light beyond the diffraction limit. They have been utilized in SPP resonance sensors and near field imaging techniques and, more recently, SPP experiments to monitor and control ultrafast charge carrier and energy relaxation dynamics in thin films. In this thesis, we discuss excitation and propagation properties of ultrafast SPPs on thin extended metal films and SPP waveguide structures. In addition, localized and propagating surface plasmon interactions in functional plasmonic nanostructures will …

Wrinkling Of Floating Thin Polymer Films, Jiangshui Huang

Doctoral Dissertations 1896 - February 2014

This thesis presents an extensive study of wrinkling of thin polystyrene films, tens of nanometers in thickness, floating on the surface of water or water modified with surfactant.

First, we study the wrinkling of floating thin polystyrene films under a capillary force exerted by a drop of water placed on its surface. The wrinkling pattern is characterized by the number and length of wrinkles. A metrology for measuring the elasticity and thickness of ultrathin films is constructed by combining the scaling relations that are developed for the length of the wrinkles with those for the number of wrinkles. This metrology …