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Symmetry And Reconstruction Of Particle Structure From Random Angle Diffraction Patterns, Sandi Wibowo

Theses and Dissertations

The problem of determining the structure of a biomolecule, when all the evidence from experiment consists of individual diffraction patterns from random particle orientations, is the central theoretical problem with an XFEL. One of the methods proposed is a calculation over all measured diffraction patterns of the average angular correlations between pairs of points on the diffraction patterns. It is possible to construct from these a matrix B characterized by angular momentum quantum number l, and whose elements are characterized by radii q and q’ of the resolution shells. If matrix B is considered as dot product of vectors, which …

Correction To Luminosity Measurement For The Pixel Luminosity Telescope At Cms, Krishna Thapa

Masters Theses

The search for and detailed study of new particles and forces with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) of CERN is fundamentally dependent on the precise measurement of the rate at which proton-proton collisions produce any particles, the so-called luminosity. Therefore, a new detector, the Pixel Luminosity Telescope (PLT), dedicated to measure the luminosity at high precision was added to the CMS experiment in 2015. It measures the inclusive charged particle production from each collision of proton bunches in the LHC. Additional charged particles which are observed by the instrument but produced from sources …

Comparison Of Simulation And Hands-On Labs In Helping High School Students Learn Physics Concepts, Matthew Charles Rytting

Theses and Dissertations

The purpose of the research was to determine whether PhET simulation labs or hands-on labs were more effective in helping students learn physics concepts. This measure was done by comparing quiz scores using recall, calculation, and transfer questions. Additionally, student perceptions of learning from both hands-on and simulation lab experiences were measured. Six labs were conducted with high school physics students on the topics of momentum, energy, circuits, angular momentum, pendulums, and friction. It was found that PhET simulation labs were as effective at creating student understanding, and sometimes more effective, as measured by quizzes given after the labs. Additionally, …

The Role Of Partial Surface Charge Compensation In The Properties Of Ferroelectric And Antiferroelectric Thin Films, Elena Glazkova

USF Tampa Graduate Theses and Dissertations

Ferroelectric and antiferroelectric ultrathin films have attracted a lot of attention recently due to their remarkable properties and their potential to allow for device miniaturization in numerous applications. However, when the ferroelectric films are scaled down, it brings about an unavoidable depolarizing field. A partial surface charge compensation allows to control the residual depolarizing field and manipulate the properties of ultrathin ferroelectric films. In this dissertation we take advantage of atomistic first-principles-based simulations to expand our understanding of the role of the partial surface charge compensation in the properties of ferroelectric and antiferroelectric ultrathin films.

The application of our computational …

Detecting Conceptual Change With Latent Transition Analysis, Glen Davenport

Doctoral Dissertations

To uphold the core premise of cognitive diagnostic assessment, it is necessary to align different aspects of assessment design. The structure of the test, the measurement model, and the score reporting must align with each other and with the construct being targeted. Conceptual knowledge, as targeted by the Force and Motion Conceptual Evaluation (FMCE), can be modeled as a set of overlapping categorical states. As such, latent class analysis (LCA) is the most appropriate measurement model—where students have a probabilistic membership within classes that tend to match with observed mental models.

This dissertation focuses on one particular application of conceptual …

Flickering Analysis Of Ch Cygni Using Kepler Data, Thomas Holden Dingus

Undergraduate Honors Theses

Utilizing data from the Kepler Mission, we analyze a flickering phenomenon in the symbiotic variable star CH Cygni. We perform a spline interpolation of an averaged lightcurve and subtract the spline to acquire residual data. This allows us to analyze the deviations that are not caused by the Red Giant’s semi-regular periodic variations. We then histogram the residuals and perform moment calculations for variance, skewness, and kurtosis for the purpose of determining the nature of the flickering. Our analysis has shown that we see a much smaller scale flickering than observed in the previous literature. Our flickering scale is on …

Determination Of The Polarization Observables Cx, Cz, And Py For Final-State Interactions In The Reaction −!D ! K+−!N, Tongtong Cao

Theses and Dissertations

The hyperon-nucleon (YN) interaction plays a key role in hypernuclei and strange nuclear matter and is an important part of the baryon-baryon interaction. While considerable progress has been made in the understanding of the nucleon-nucleon (NN) interaction, the YN interaction is less known. Some parameters of the YN potential can be obtained from the NN potential by using SU(3) symmetry. However, due to broken SU(3) there are parameters, which must be obtained from fits to experimental data. High-statistics data on exclusive photoproduction off the deuteron initiated with highly-polarized photons offer a unique opportunity to extract a large sample of polarization …

Sensitivity Of The Cuore Detector To Solar Axions, Dawei Li

Theses and Dissertations

The strong CP problem in Quantum Chromodynamics (QCD), predicts the neutron electric dipole moment to be a factor of 1010 larger than the observed upper bound [15]. Roberto Peccei and Helen Quinn [58, 63] proposed an elegant solution to this problem by introducing a global U(1)PQ symmetry that is spontaneously broken at an energy scale fa. A consequence of this symmetry-breaking is that a new spin-zero neutral pseudoscalar particle, the axion, is generated which is a Nambu-Goldstone boson [70, 78]. The “invisible axion” models with fa >> fEW, typically KSVZ and DFSZ models, have been proposed and recognized to be far-reaching …

The Smoluchowski Equation In Population Dynamics And The Spread Of Infection, Satomi Sugaya

Physics & Astronomy ETDs

This dissertation is a report on an interdisciplinary investigation consisting of an application of random walk techniques to problems in ecology, particularly to the spread of Hantavirus epidemic among rodents that live on an open terrain. The population of mice that we consider is made up of infectious disease-carrying mice and susceptible mice that are disease-free, and each mouse has its own home range around which it executes a random walk. We describe an event of infection transmission in such a population via reaction-diffusion theory. Our simple model consists of two mice, one infected and the other susceptible, the disease …

Poe's Entangled Fiction: Quantum Field Theory In "The Colloquy Of Monos And Una" And "The Mystery Of Marie Rogêt", Jean A. Little

Theses and Dissertations

When seen among the constellation of Edgar Allan Poe's works culminating in Eureka, "The Colloquy of Monos and Una" and "The Mystery of Marie Rogêt," take on an important role as vehicles for scientific contemplation. Similar to early quantum physicists, such as Einstein and Schrödinger, Poe uses macro-level analogies to explore the unity of individual entities, which becomes an important tenet of his explanation of the universe. His thought experiments also resemble those of modern physics in their approach to reality as probabilistic, an idea that finds its echo in quantum field theory, which distinguishes between observed particles and their …

Sensing Gyroscopic Properties Of Rotating Magnetic Nanoparticles In Solution, Brian Gerald Krug

Dissertations

A new sensor using magnetic nanoparticles and rotating magnetic fields has been developed. By spinning the nanoparticles in a rotating magnetic field, it is feasible to infer angular position and inertia if an external force is applied to the system. The nanoparticles are treated as a multitude of miniature gyroscopes whose overall effect can be combined as one single gyroscope. Two sensors were built to test the feasibility, both containing Fe3O4 nanoparticles.

The typical input current was 250 milliamps. When the sensor deviated from its magnetic axis by a small angle, the input current changed between 1 and 2 milliamps …

Elements Of The Mathematical Formulation Of Quantum Mechanics, Keunjae Go

Senior Honors Papers / Undergraduate Theses

In this paper, we will explore some of the basic elements of the mathematical formulation of quantum mechanics. In the first section, I will list the motivations for introducing a probability model that is quite different from that of the classical probability theory, but still shares quite a few significant commonalities. Later in the paper, I will discuss the quantum probability theory in detail, while paying a brief attention to some of the axioms (by Birkhoff and von Neumann) that illustrate both the commonalities and differences between classical mechanics and quantum mechanics. This paper will end with a presentation of …

Measurements Of Photon Beam Intensity At The High Intensity Gamma-Ray Source (Higs) Facility For Astrophysically Relevant Photodisintegration Reaction Cross Section, Evan G. Meekins

Senior Honors Projects, 2010-2019

How nuclear reactions in stars and stellar explosions such as supernovae have forged the elements out of hydrogen and helium leftover from the Big Bang is a longstanding, still timely research topic in nuclear astrophysics. Although there is a fairly complete understanding of the production of the chemical elements and their isotopes up to iron by nuclear fusion in stars, important details concerning the production of the elements from iron to uranium remain puzzling. Current knowledge is that the nucleosynthesis beyond iron proceeds mainly via neutron capture reactions and subsequent electron decays to stability. However, some 35 proton-rich stable isotopes, …

Fundamental Physics With Cold Neutron Beams, Kyle Brandon Grammer

Doctoral Dissertations

The neutron exhibits rich physics both as a tool for studying materials, particle and nuclear physics, as well as the object of experimental study. The neutron lifetime is an important input to Big Bang Nucleosynthesis models and is currently known only to approximately 0.3\% with the most precise measurements from two different experimental techniques in disagreement by more than 3$\sigma$ [sigma]. Parity violation has been the subject of study since its discovery in 1957. Parity violation experiments provide access to studying the hadronic weak interaction, which is otherwise suppressed by several orders of magnitude below that of the strong interaction. …

Synthesis, Characterization, And Electronic Properties Of Novel 2d Materials : Transition Metal Dichalcogenides And Phosphorene., George Anderson

Electronic Theses and Dissertations

Scaling electronic devices has become paramount. The current work builds upon scaling efforts by developing novel synthesis methods and next generation sensing devices based on 2D materials. A new combination method utilizing thermal evaporation and chemical vapor deposition was developed and analyzed to show the possibilities of Transition Metal Dichalcogenide monolayers and heterostructures. The materials produced from the above process showed high degrees of compositional control in both spatial dimensions and chemical structure. Characterization shows controlled fabrication of heterostructures, which may pave the way for future band gap engineering possibilities. In addition, Phosphorene based field effect transistors, photodetectors, and gas …

Surface Effect Of Ferromagnetic Nanoparticles On Transition Between Single- And Multi-Domain Structure Or Between Single-Domain Structure And Superparamagnetic Phase, Hind Adawi

Browse all Theses and Dissertations

Surface effects on critical dimensions of ferromagnetic nanoparticles were studied. Algebraic equations were derived and numerically solved for critical radius RC2 of ferromagnetic nanoparticles describing the transition between single- and multi-domain magnetic structure. Results were analyzed to illustrate the effect of surface parameters related to saturation magnetization a, exchange interaction ß, and anisotropy KS on the critical radius of nanoparticles with a core value of anisotropy KV. Available experimental data for MnBi, FePt, and CoPt or for Fe nanoparticles were used as examples of nanoparticles with high and low values of KV, respectively. Our studies clearly show that discrepancies existing …

Nonlinear Evolution Of Mirror Instability In The Earth's Magnetosheath In Pic Simulations, Narges Ahmadihojatabad

Doctoral Dissertations

Mirror modes are large amplitude non-propagating structures frequently observed in the magnetosheath and they are generated in space plasma environments with proton temperature anisotropy of larger than one. The proton temperature anisotropy also drives the proton cyclotron instability which has larger linear growth rate than that of the mirror instability. Linear dispersion theory predicts that electron temperature anisotropy can enhance the mirror instability growth rate while leaving the proton cyclotron instability largely unaffected. Contrary to the hypothesis, electron temperature anisotropy leads to excitement of the electron whistler instability. Our results show that the electron whistler instability grows much faster than …

"Smoking-Gun" Observables Of Magnetic Reconnection: Spatiotemporal Evolution Of Electron Characteristics Throughout The Diffusion Region, Jason Shuster

Doctoral Dissertations

How does magnetic reconnection happen in a collisionless plasma? Knowledge of electron-scale dynamics is necessary to answer this outstanding question of plasma physics. Based on fully kinetic particle-in-cell (PIC) simulations of symmetric reconnection, the spatiotemporal evolution of velocity distribution functions in and around the electron diffusion region (EDR) elucidates how electrons are accelerated and heated by the cooperating reconnection electric and normal magnetic fields. The discrete, triangular structures characteristic of EDR distributions rotate and gyrotropize in velocity space as electrons remagnetize, forming multicomponent arc and ring structures. Further downstream, exhaust electrons are found to exhibit highly structured, time-dependent anisotropies that …

Quantifying The Role Of The Seed Population In Radiation Belt Dynamics, Alexander Boyd

Doctoral Dissertations

The dynamics of the radiation belts depend on a delicate balance of source and loss processes. One such source process that has been shown to be effective is local acceleration, where 10s-100s keV seed electrons are accelerated via wave-particle interactions up to energies >1 MeV. Historically, much of the focus of radiation belt research has been on the dynamics of these >1 MeV electrons, and the role and importance of the seed electrons has been largely overlooked. In this thesis, we use phase space density calculated using data from the Van Allen Probes, to directly investigate seed population for a …

Analyzing The Interstellar Neutral He Bulk Flow Parameters With Ibex-Lo, Trevor Leonard

Doctoral Dissertations

Our Sun is immersed in a local galactic environment which is composed of a warm, dilute, and partially ionized gas. Due to the Sun’s motion relative to this environment, the interstellar neutral (ISN) gas flows through the heliosphere providing the opportunity to perform in-situ observations of the ISN gas from Earth’s orbit. The Interstellar Boundary Explorer (IBEX) has observed the ISN gas flow over the past 7 years from a highly elliptical orbit around the Earth. The first observations of ISN H, O, and Ne were recorded by IBEX, along with the most detailed observation of ISN He. Since He …

Small Solar Wind Transients 1995 - 2014: Properties, Modeling, And Effects On The Magnetosphere, Wenyuan Yu

Doctoral Dissertations

Using case studies and statistical analysis on a large data sample we investigate properties of small solar wind transients (STs) and discuss their modeling. The observations are from the Wind and STEREO spacecraft. By "small" we mean a duration of 0.5-12 hours. We do not restrict ourselves to magnetic flux ropes. Having arrived at a definition based on an extension of previous work, we apply an automated algorithm to search for STs. In one chapter we focus on the solar activity minimum years 2007-2009. We find an average ST duration of ~4.3 hours, with 75% lasting less than 6 hours. …

New Computational Approaches To The N-Body Problem With Applications To The Electron Cooling Of Heavy Ion Beams, Pulukkuttige D. Sumana Abeyratne

Graduate Research Theses & Dissertations

Thomas Jefferson National Accelerator Facility (JLab) has proposed a new Electron-Ion Collider, JLEIC. In this collider, a polarized electron beam and a counter rotating ionbeam collide at the interaction point(s). A critical problem for the JLEIC collider is cooling the ion beam to ensure small emittance and to achieve high luminosity. Since electron cooling—a method of cooling ‘hot’ ion beams through Coulomb interactions with ‘cold’ electron beams—is one of the most effective cooling methods, it will be used by JLEIC. However, the most naive way of calculating Coulomb forces through the pair-wise method becomes infeasible even with the most high …

The Development Of A Computerized Interactive Teaching Assistant In Physics: The Cita On Chip Project, Cyrus Marazban Vandrevala

Open Access Dissertations

One of the many roles of university instructors is to provide help to students throughout the semester - especially in the form of feedback on homework. Personalized feedback from the instructor might be possible in a small classroom setting, but becomes unmanageable when class sizes grow to dozens or even hundreds of students. As a result, universities are turning to computerized homework systems that guide students through problems and provide focused grades and feedback.

Molecular Dynamics Simulations Of A Pentacene Derivative On Gold Surfaces In The Quantum Mechanical And Classical Mechanics Frameworks, Ryan Allen Miller

Master's Theses and Capstones

With increasing potential to serve as a basis for constructing organic photovoltaic de- vices, the directed self-assembly of small organic molecules on metal substrates provides an interesting new method of bottom-up device building. By utilizing the qualities inherent in the substrate and molecules, one can manipulate surface topology to create functional layers of molecules in a desired configuration. However, tailoring these organic layers in a useful way requires detailed analysis of the substructure characteristics. With top-down visualization approaches like Scanning Tunneling Microscopy (STM) pro- viding a limited view of assembled layer structural characteristics, molecular dynamics sim- ulations must be employed …

Effect Of Modeling Instruction On Concept Knowledge Among Ninth Grade Physics Students, Devin Alan Ditmore

Walden Dissertations and Doctoral Studies

A basic knowledge of physics concepts is the gateway to success through high-paying careers in science, technology, engineering, and mathematics (STEM). Many students show little understanding of concepts following traditional physics instruction. As an alternative to current lecture-based approaches for high school physics instruction, Piaget's theory of cognitive development supports using real scientific experiences to lead learners from concrete to formal understanding of complex concepts. Modeling instruction (MI) is a pedagogy that guides learners through genuine scientific experiences. This project study analyzed the effects of MI on 9th grade physics students' gains on the test measuring mastery of physics concepts, …

The Effect Of Impurities On The Superconductivity Of Bscco-2212, John Vastola

Honors Undergraduate Theses

BSCCO-2212 is a high-temperature cuprate superconductor whose microscopic behavior is currently poorly understood. In particular, it is unclear whether its order parameter is consistent with s-wave or d-wave symmetry. It has been suggested that its order parameter might take one of several forms that are consistent with d-wave behavior. We present some calculations using the many-body theory approach to superconductivity that suggest that such order parameters would lead to a suppression of the critical temperature in the presence of impurities. Because some experiments have suggested the critical temperature of BSCCO-2212 is relatively independent of the concentration of impurities, this lends …

A Comparative Analysis Of Photon And Electron Wave Functions In Spherically Symmetric Potentials, Michael Bush

Senior Independent Study Theses

No abstract provided.

The Production And Manipulation Of Nonseparable Spin-Orbit Modes Of Light Under Hong-Ou-Mandel Interference Conditions, Maggie E. Lankford

Senior Independent Study Theses

No abstract provided.

Wavelet Transform Of Optical Conductivity Of Bi2sr2cacu2o8+X In The Normal And Superconducting State, Patrick Janovick

Williams Honors College, Honors Research Projects

This paper compares the wavelet transform of the optical conductivity of Bi₂Sr₂CaCu₂O_8+x in both the normal and the superconducting state. The wavelet transforms of the normal and superconducting state are also compared with wavelet transforms of the Drude model as well as the Lorentz model. The wavelet transform of the collected data for Bi₂Sr₂CaCu₂O_8+x is similar in shape to the Drude model. The wavelet transform of the collected data in the normal state corresponds to the Drude model with a high scattering rate and the collected …

Correlations Between Introductory Students’ Attitudes About Physics And Conceptual Understanding, Raym Alzahrani

Browse all Theses and Dissertations

The purpose of this study is to measure correlations between the students’ incoming attitudes, beliefs and expectations about physics and their conceptual understanding. The study presents a profile of the attitudes and beliefs for Wright State University students who enrolled in calculus-based General Physics I courses during academic years 2014-2015 and 2015-2016. Students’ initial and final attitudes, measured using the CLASS, are correlated with initial and final conceptual gain, measured using the Force Concept Inventory. Students’ initial attitudes (Opre) was correlated with students’ gain (FCIgain) in many sections. Correlations between students’ final attitudes (Opost) and their conceptual understanding (FCIpost), reported …