Physics Commons^™

Development Of An Innovative Observational Astronomy Class For High School Students In Collaboration With The University Of Texas/Rio Grande Valley, Alan W. Hendrick

Theses and Dissertations

The vision presented by the National Academy of Science Standards is for all students to spend more time ‘doing’ science in order to develop science literacy and be better prepared not only for college but also in understanding and participation in global current events. A course in observational Astronomy is just that, an opportunity for student to “do ‘science by collaborating with actual scientists in real research. The course follows a path in which students learn foundational knowledge and apply this knowledge to complete a successful celestial observation, interpreting the results by making inferences and predictions. This paper begins with …

Star Formation Density And Galactic Outflows At Z~2, Matthew Coon

Theses and Dissertations

Galactic-scale outflows of gas play a significant role in galaxy evolution. They push gas to larger radii, slowing the star formation rate near the center of the galaxy, and increasing it at larger radii. Eventually, these outflows can expel the gas from the galaxy, depositing metals into the intergalactic medium, and limiting star formation in the galaxy. Galaxies from the Keck Baryonic Structure Survey (KBSS) and 3D- Hubble Space Telescope (3D-HST) Survey were used in order to measure the velocities of galactic outflows from the KBSS spectra, and the grism spectra from the 3D- HST survey were used in order …

Nanoenergetic Gas Generators Based On Metal Hydroxides, Srbuhi Yolchinyan

Theses and Dissertations

The metal oxide based nano thermites have been studied extensively, yet another closely related systems based on metal hydroxides were surprisingly overlooked. For the first time, the thermodynamic calculations using HSC Chemistry-7 and Thermo software, were performed for a collection of 22 novel nano-thermite systems based on aluminum and metal hydroxides, and four representative systems based on bismuth, copper, cerium and nickel hydroxides were characterized using differential scanning calorimeter, scanning electron microscope, and pressure discharge dynamic evaluation. The strongest performance was recorded in Al-Bi(OH)3 system with about 4.9 MPa peak pressure for 0.2 g charge mass. Bismuth oxide and hydroxide …

Development Of Large-Area Gem Detectors For The Forward Muon Endcap Upgrade Of The Cms Experiment And Search For Sm Higgs Boson Decay In The H → Τ+Τ− → Μ+Μ−¯Νμνμ¯Ντντ Channel At √ S = 13 Tev, Vallary Shashikant Bhopatkar

Theses and Dissertations

Gas Electron Multiplier (GEM) technology is being considered for the forward muon upgrade of the Compact Muon Solenoid (CMS) experiment in Phase II of the CERN LHC. The first GEM Endcap (GE1/1) is going to be installed in the 1.5 <| η |< 2.2 region of the muon endcap mainly to control muon level-1 trigger rates after the second long LHC shutdown. A GE1/1 triple-GEM detector is read out by 3,072 radial strips with 453 µrad pitch arranged in eight η-sectors. A meter-long GE1/1 prototype-III was assembled at Florida Tech and tested in 20-120 GeV hadron beams at Fermilab using Ar/CO2 70:30 and the RD51 Scalable Readout System (SRS). Four GEM detectors with 2-D readout and an average measured azimuthal resolution of 36µrad provided precise reference tracks. Construction of this GE1/1 prototype-III detector and its performance in the test beam are described. Strip cluster parameters, detection efficiency, and spatial resolution are studied with position and high voltage scans. The plateau detection efficiency is [97.80 ± 0.2 (stat)]%. The azimuthal resolution is found to be [123.5 ± 1.6 (stat)] µrad when operating in the center of the efficiency plateau and using full pulse height information. The CMS upgrade design calls for readout electronics with binary hit output. When strip clusters are formed correspondingly without charge-weighting and with fixed hit thresholds, a position resolution of [136.8 ± 2.5 stat] µrad is measured, consistent with the expected resolution from strip-pitch/√ 12 = 131.3 µrad. The eight η-sectors of the detector show a similar response and performance. VFAT3 electronics are being considered for the readout system of GE1/1 detectors. The charge that is induced on the GE1/1 readout strips by minimum-ionizing particles is an important parameter that informs the design of the amplifier-shaper input stage of the VFAT3 chip. To estimate the input charge range for these electronics, the most probable value, mean value, and 99th percentile value of the Landau distribution of the charge induced on a single strip are measured and found to be 4 fC, 11 fC, and 115 fC, respectively. The Z/γ∗ → τ τ cross section in proton-proton collisions at √ s = 13 TeV is measured, using data recorded by the CMS experiment at the LHC during 2015 and corresponding to an integrated luminosity of 2.3 fb−1 . The product of the cross section and branching fraction is measured in the dimuon final state to be 1967 ± 121 (stat.) ± 92 (syst.) ± 37 (lumi.) pb, in agreement with the standard model expectation, computed at next-to-next-to-leading order accuracy in perturbative quantum chromodynamics. A search for Standard Model (SM) Higgs bosons decaying into pairs of tau leptons and then to two muons plus (anti)-neutrinos is performed using the data collected by the CMS detector in 2016 with 35.9 fb−1 of integrated luminosity. The upper limits on the cross section relative to SM prediction are calculated in three event categories with different jet multiplicities focusing on Higgs boson signal events produced via gluon-gluon fusion and vector boson fusion. A multivariate analysis with Boosted Decision Trees (BDT) is used to suppress the large Drell-Yan background. The di-tau mass is reconstructed using a Secondary-Vertex fit (SVFit) algorithm using a maximum likelihood approach. Experimental limits are presented in all three categories extracted from the maximum likelihood fit of reconstructed di-tau mass and the visible mass of the dimuon system. The signal strength for the combination of all three categories is estimated as -1.0 ± 1.7. The expected and observed upper limits with 95% CL is at 3.2 and 2.7, respectively, with respect to the SM cross section times branching fraction.

Computational Exploration Of Vortex Nucleation In Type Ii Superconductors Using A Finite Element Method In Ginzburg-Landau Theory, Alden Roy Pack

Theses and Dissertations

Using a finite element method, we numerically solve the time-dependent Ginzburg-Landau equations of superconductivity to explore vortex nucleation in type II superconductors. We consider a cylindrical geometry and simulate the transition from a superconducting state to a mixed state. Using saddle-node bifurcation theory we evaluate the superheating field for a cylinder. We explore how surface roughness and thermal fluctuations influence vortex nucleation. This allows us to simulate material inhomogeneities that may lead to instabilities in superconducting resonant frequency cavities used in particle accelerators.

Computational Exploration Of Vortex Nucleation In Type Ii Superconductors Using A Finite Element Method In Ginzburg-Landau Theory, Alden Roy Pack

Theses and Dissertations

Using a finite element method, we numerically solve the time-dependent Ginzburg-Landau equations of superconductivity to explore vortex nucleation in type II superconductors. We consider a cylindrical geometry and simulate the transition from a superconducting state to a mixed state. Using saddle-node bifurcation theory we evaluate the superheating field for a cylinder. We explore how surface roughness and thermal fluctuations influence vortex nucleation. This allows us to simulate material inhomogeneities that may lead to instabilities in superconducting resonant frequency cavities used in particle accelerators.

Characterization Of Military Aircraft Jet Noise Using Wavepacket Analysis And Other Array Processing Methods, Blaine M. Harker

Theses and Dissertations

Sound generation and radiation properties are studied of full-scale tactical jet engine noise. This is motivated by the high sound exposure levels from jet noise, particularly for tactical engines. Acoustic source reconstruction methods are implemented computationally on existing jet noise data. A comparative study is performed using numerical simulations to understand the capabilities of more advanced beamforming methods to successfully estimate the source properties of a distributed, partially correlated source distribution. The properties and limitations of each beamforming method are described. Having validated the methods, beamforming with regularization”via the Hybrid Method”is implemented on linear array measurements near an installed tactical …

Characterization Of Military Aircraft Jet Noise Using Wavepacket Analysis And Other Array Processing Methods, Blaine M. Harker

Theses and Dissertations

Sound generation and radiation properties are studied of full-scale tactical jet engine noise. This is motivated by the high sound exposure levels from jet noise, particularly for tactical engines. Acoustic source reconstruction methods are implemented computationally on existing jet noise data. A comparative study is performed using numerical simulations to understand the capabilities of more advanced beamforming methods to successfully estimate the source properties of a distributed, partially correlated source distribution. The properties and limitations of each beamforming method are described. Having validated the methods, beamforming with regularization—via the Hybrid Method—is implemented on linear array measurements near an installed tactical …

Special Features Of The Air-To-Space Neutron Transport Problem, Whitman T. Dailey

Theses and Dissertations

Special features of the air-to-space neutron transport problem are identified, characterized, and quantified to provide information on features that should be included in Monte Carlo simulations to obtain accurate predictions. Currently available codes and tools for Monte Carlo neutron transport calculations do not provide an adequate (in accuracy nor precision nor efficiency) framework for practical transport calculations in the context of the air-to-space neutron transport problem. A new Fortran code, High Altitude Transport to Space for Neutrons (HATS-n), is developed and tested to perform high fidelity Monte Carlo neutron transport calculations for this class of problems. Special features of the …

Laser Heating Of Graphite And Pulsed Laser Ablation Of Titanium And Aluminum, William A. Bauer

Theses and Dissertations

Tactical missions for laser weapons include a wide variety of targets, increasing the demands on the laser lethality community. New approaches to reducing the dimensionality of laser and materials interactions are necessary to increase predictive capability. Self-contained systematic experimental study was conducted on continuous wave and pulsed laser interaction with graphite, Al, and Ti. The spectroscopy and plume dynamics from the heating and ablation of these materials was examined to characterize laser weapons effects, develop graphite response for thermal protection systems, and provide optical diagnostics for materials processing. Furthermore, analysis of ablated plume velocity distributions shows application of conventional Maxwell-Boltzmann …

Luminescence In Lithium Borates, Brant T. Kananen

Theses and Dissertations

Spectrometry methods are used to identify and characterize point defects in single crystals of lithium tetraborate (Li₂B₄O₇) and lithium triborate (LiB₃O₅) doped with silver or copper, and explore the role of these point defects in luminescence. New defects are identified in Ag-doped including: lithium vacancy substitutional-silver-ion defect-pairs (hole trap); isolated lithium vacancies (hole trap); isolated oxygen vacancies (electron trap); interstitial-silver-ion substitutional-silver-ion defect pairs (electron trap); isolated interstitial silver ions (electron trap); and interstitial-silver-ion lithium-vacancy defect pairs (electron trap). Defect models are proposed, and adjustments made to defect models known defects. …

Three-Dimensional Imaging Of Cold Atoms In A Magneto-Optical Trap With A Light Field Microscope, Gordon E. Lott

Theses and Dissertations

Imaging of trapped atoms in three dimensions utilizing a light field microscope is demonstrated in this work. Such a system is of interest in the development of atom interferometer accelerometers in dynamic systems where strictly defined focal planes may be impractical. A light field microscope was constructed utilizing a Lytro® Development Kit micro-lens array and sensor. It was used to image fluorescing rubidium atoms in a magneto-optical trap. The three-dimensional (3D) volume of the atoms is reconstructed using a modeled point spread function (PSF), taking into consideration the low magnification (1.25) of the system which changed typical assumptions in the …

Analysis Of Ar(1s5) Metastable Populations In High Pressure Argon-Helium Gas Discharges, Daniel J. Emmons Ii

Theses and Dissertations

Simulations of an argon-helium plasma are performed for two high pressure discharge scenarios to find a uniform, large-volume plasma with Ar(1s5) metastable densities on the order of 10¹³ cm^-3 for use as the ground state in an optically pumped rare gas laser. An analysis of a pulsed direct current discharge is performed for a 7% argon in helium mixture at a pressure of 270 Torr using both zero and one-dimensional models. Kinetics of species relevant to the operation of an optically pumped rare gas laser are analyzed throughout the pulse duration to identify key reaction pathways. Simulations are …

Biocidal Defeat Agents Produced By Silver-Iodine Nanoenergetic Gas Generators, Ivan Davila

Theses and Dissertations

Nanostructured aluminum (Al), iodine pentoxide (I2O5) nano-rods, and silver oxide (Ag2O) nanoparticles, (Al-I2O5-Ag 2O) were used to compose the ternary thermite composition that serves as a Nanoenergetic Gas Generator (NGG). This composition produces biocidal gases giving the mixture the ability to destroy highly pathogenic microorganisms or bacteria. The dissemination of the biocidal gas in combustion chamber was observed using a high-speed camera. The testing of NGG combustion process against the living Escherichia coli (E.coli) K-12 strain cells, that were cultivated/placed on the sample/chamber surfaces, demonstrated that iodine and silver atoms clouds were deposited to the bacteria surface. The 10/75/15 wt …

Molecular Dynamics Simulations Of Dna Duplex Stretching, Ramin Salimi

Theses and Dissertations

Single-molecule DNA stretching experiments is a an extremely rigorous method to investigate mechanical properties of DNA and how DNA molecule binding to proteins, and other small molecules works. In these experiments, double-stranded DNA molecules are stretched by a force applied to opposite ends of the DNA, e.g., in an atomic force microscope or an optical tweezers instrument. Here we study the stretching behavior of the DNA duplex d(CGCAAAAAAGCG) 2 by molecular dynamics simulations. In particular, we calculate the change in free energy ∆F = ∆U − T ∆S as the DNA duplex is stretched. We seek to show that employing …

Difference Structures From Time-Resolved Saxs/Waxs, Prakash Nepal

Theses and Dissertations

It has been thought that there is not enough information to recover a solution to the problem of inverting time-resolved Small Angle X-ray Scattering (SAXS) / Wide Angle X-ray Scattering (WAXS) difference data. In this context, this study presents a new idea by extending the concept of “difference Fourier method” which aims to overcome the above limitation in the idealized case of simulated data.

If the structural changes in a typical time-resolved studies are generally confined to a relatively localized region, they can be found from difference SAXS/WAXS curves and knowledge of the atomic coordinates of one of the states. …

Biomedical Applications Of Mid-Infrared Spectroscopic Imaging And Multivariate Data Analysis: Contribution To The Understanding Of Diabetes Pathogenesis, Ebrahim Aboualizadeh

Theses and Dissertations

Diabetic retinopathy (DR) is a microvascular complication of diabetes and a leading cause of adult vision loss. Although a great deal of progress has been made in ophthalmological examinations and clinical approaches to detect the signs of retinopathy in patients with diabetes, there still remain outstanding questions regarding the molecular and biochemical changes involved. To discover the biochemical mechanisms underlying the development and progression of changes in the retina as a result of diabetes, a more comprehensive understanding of the bio-molecular processes, in individual retinal cells subjected to hyperglycemia, is required. Animal models provide a suitable resource for temporal detection …

Modeling Gravitational-Wave Sources For Pulsar Timing Arrays, Joseph Simon

Theses and Dissertations

The recent direct detections of gravitational waves (GWs) from merging black holes by the Laser Interferometer Gravitational-wave Observatory (LIGO) marks the beginning of the era of GW astronomy and promises to transform fundamental physics. In the coming years, there is hope for detections across the mass scale of binary black holes.

Pulsar Timing Arrays (PTAs) are galactic-scale low-frequency (nHz - $\mu$Hz) GW observatories, which aim to directly detect GWs from binary supermassive black holes (SMBHs) ($\gtrsim 10^{7} \msun$). The frequency and black hole mass range that PTAs are sensitive to is orders of magnitude different from those LIGO is observing, …

Galactic Outflows And Their Correlations With Galaxy Properties At 0.8 < Z < 1.6, Lindsey Whiting

Theses and Dissertations

Out

ows have been shown to be ubiquitous in galaxies between z = 1 and z=2,

and many models and observations have attempted to correlate the absorption line

properties of these out

ows with morphological characteristics of their host galaxies.

In this study, we examined the spectra of 71 galaxies with redshifts 1< z<2, paying

particular attention to the FeII and MgII absorption lines. We plotted the equivalent

width, velocity, and maximum velocity of the absorption features against various

physical properties of the galaxies, obtained from catalogues created by Skelton et

al., (2014) and van der Wel et al., (2012). We conrmed …

Thermal Consolidation Of Dredge Sand For Artificial Reef Formations, Alexandro Trevino

Theses and Dissertations

Coral Reef ecosystems have degraded over years due to a variety of environmental issues such as ocean acidification. The continuous stress has detrimental effects on coral reef ecosystems that can possibly lead to the loss of the ecosystem. Our research aims to construct a prototype of an artificial reef by consolidating dredge sand from the ship channels of South Texas. Consolidation is achieved through an aluminum polytetrafluoroethylene self-propagating high temperature process that yields a solid formation to mimic the physical properties of coral reef structures. Using thermodynamic calculations, the variation of initial components was determined that reached an adiabatic temperature …

Investigation Of Membrane Receptors’ Oligomers Using Fluorescence Resonance Energy Transfer And Multiphoton Microscopy In Living Cells, Ashish K. Mishra

Theses and Dissertations

Investigating quaternary structure (oligomerization) of macromolecules (such as proteins and nucleic acids) in living systems (in vivo) has been a great challenge in biophysics, due to molecular diffusion, fluctuations in several biochemical parameters such as pH, quenching of fluorescence by oxygen (when fluorescence methods are used), etc.

We studied oligomerization of membrane receptors in living cells by means of Fluorescence (Förster) Resonance Energy Transfer (FRET) using fluorescent markers and two photon excitation fluorescence micro-spectroscopy. Using suitable FRET models, we determined the stoichiometry and quaternary structure of various macromolecular complexes. The proteins of interest for this work are : (1) sigma-1 …

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 …

Accelerated Quantum Dynamics, Morgan Henry Lynch

Theses and Dissertations

In this dissertation we develop a formalism for the computation of observables due to acceleration-induced particle physics processes. By using the spacetime structure produced by acceleration, we examine the properties of accelerated particle detectors as well as accelerated fields. General expressions for the transition rate, multiplicity, power, spectra, and displacement law of particles undergoing time-dependent acceleration and transitioning into a final state of arbitrary particle number are obtained. The transition rate, power, and spectra are characterized by unique polynomials of multiplicity and thermal distributions of both bosonic and fermionic statistics. The acceleration-dependent multiplicities are computed in terms of the branching …

Characterization Of Neutron And Proton Exposure On The Radiation Resistant Bacterium, Deinococcus Radiodurans, Ronald C. Lenker

Theses and Dissertations

Deinococcus radiodurans is a robust bacterium that is known for its extraordinary resistance to ionizing radiation. In general, many of the investigations of this bacterium's resistance have revolved around low linear energy transfer radiation, such as gamma and electron radiation. This study explored Deinococcus radiodurans's ability to survive high linear energy transfer radiation, specifically proton and neutron radiation. Deinococcus radiodurans was dehydrated to reduce the effects of low linear energy transfer radiation. The bacteria were exposed to both neutron and proton radiation of varying amounts and rehydrated. The resulting colonies were counted and compared to colonies of non-irradiated control samples …

Cavity Perturbation Technique Of 10 Ghz Cylindrical Resonator For Modeling Rf/Ir Sensor Radomes/Windows, Marvin-Ray Arida

Theses and Dissertations

The dielectric properties of candidate materials for radomes or sensor windows on hypersonic vehicles, which can reach temperatures above 1,500° Celsius when traveling greater than Mach 5, are required. Although there has been recent scientific interest in the temperature dependence of the dielectric constant, little is known for temperatures near 1,500° Celsius and above. Current research utilizes large laboratory-sized furnaces to achieve these temperatures. This also requires large sample sizes, which are expensive; such expense is greatly multiplied when sweeping through hundreds of materials for research and development. In an effort to reduce these costs, this thesis modeled a 7.0 …

Using Principal Component Analysis To Improve Fallout Characterization, Derek W. Haws

Theses and Dissertations

Previous research conducted at Lawrence Livermore National Laboratory (LLNL) and the Air Force Institute of Technology (AFIT) has shown a correlation between actinide location and elemental composition in fallout from historic weapons testing. Fifty spherical fallout samples were collected from near ground zero of a surface burst weapons test. The samples were mounted in an aluminum puck then ground and polished to a hemisphere exposing the central plane. Physical morphologies of the samples ranged from clear to opaque with inclusions, voids, and/or uniform characteristics. Spectroscopy data were collected using optical microscopes and scanning electron microscopy (SEM), with radioactivity recorded through …

Rbhe Potential Energy Surface Sensitivity Study, Ethan D. Thorp

Theses and Dissertations

This paper studies how alterations of features of RbHe potential energy surfaces (PES) for a diode pumped alkali laser (DPAL) system effect the collisional cross section. The Split-Operator method is used to propagate a wave function along these PES and because they are radially coupled, the wave function can be transmitted from the starting surface to other energy surfaces. This transmittance is encoded in the correlation function. The full Hamiltonian used for propagation consists of the electronic potential, the nuclear kinetic energy, and the Coriolis coupling. The correlation function is used to generate the Scattering Matrix elements. These elements describe …

Total Electron Count Variability And Stratospheric Ozone Effects On Solar Backscatter And Lwir Emissions, John S. Ross

Theses and Dissertations

The development of an accurate ionospheric Total Electron Content (TEC) model is of critical importance to High Frequency (HF) radio wave propagation. However, the TEC is highly variable and is continuously influenced by geomagnetic storms, extreme Ultraviolet (UV) radiation, diurnal variation, and planetary waves. The ability to capture this variability is essential to improve current TEC models. Analysis of the growing body of data involving ionospheric fluctuations and thermal tides has revealed persistent correlation between increases in stratospheric ozone and variability of the TEC. The spectral properties of ozone show that it is a greenhouse gas that alters longwave emissions …

Modeling The White Sands Missile Range Fast Burst Reactor Using A Discrete Ordinates Code, Pentran, Taylor R. Schulmeister

Theses and Dissertations

The goal of this research was to develop and characterize a deterministic model of a fast burst reactor (FBR) using a discrete ordinates neutral particle transport code, PENTRAN. The White Sands Missile Range FBR design was chosen for this research because this FBR is important to the DoD due to its short duration, high energy neutron flux which is representative of the neutron flux output created by a nuclear weapon. One, two, and three dimensional PENTRAN models of the FBR were developed and neutron transport based eigenvalue calculations were performed. These eigenvalue calculations were conducted using two different set of …

A Computational Study: The Effect Of Hypersonic Plasma Sheaths On Radar Cross Section For Over The Horizon Radar, Zachary W. Hoeffner

Theses and Dissertations

In this study radar cross sections were calculated for an axial symmetric 6-degree half angle blunted cone with a nose radius of 2.5 cm and length of 3.5 m including and excluding the effects of an atmospheric hypersonic plasma sheath for altitudes of 40 km, 60 km and 80 km and speeds of 5 km/s, 6 km/s and 7 km/s. LAURA, was used to determine the plasma characteristics for the hypersonic flight conditions using a 11-species 2-temperature chemical model. Runs were accomplished first with a super-catalytic surface boundary condition without a turbulence model and then for some cases with an …