Digital Commons Network^™

Hydrodynamic And Magnetohydrodynamic Computations Inside A Rotating Sphere, P. D. Mininni, D. C. Montgomery, L. Turner

Dartmouth Scholarship

Numerical solutions of the incompressible magnetohydrodynamic (MHD) equations are reported for the interior of a rotating, perfectly-conducting, rigid spherical shell that is insulator-coated on the inside. A previously-reported spectral method is used which relies on a Galerkin expansion in Chandrasekhar–Kendall vector eigenfunctions of the curl. The new ingredient in this set of computations is the rigid rotation of the sphere. After a few purely hydrodynamic examples are sampled (spin down, Ekman pumping, inertial waves), attention is focused on selective decay and the MHD dynamo problem. In dynamo runs, prescribed mechanical forcing excites a persistent velocity field, usually turbulent at modest …

Classical-Quantum Correspondence In Electron-Positron Pair Creation, N I. Chott, Qichang Su, Rainer Grobe

Faculty publications – Physics

We examine the creation of electron-positron pairs in a very strong force field. Using numerical solutions to quantum field theory we calculate the spatial and momentum probability distributions for the created particles. A comparison with classical mechanical phase space calculations suggests that despite the fully relativistic and quantum mechanical nature of the matter creation process, most aspects can be reproduced accurately in terms of classical mechanics.

Nonlinear Dynamics In Combinatorial Games: Renormalizing Chomp, Eric J. Friedman, Adam S. Landsberg

WM Keck Science Faculty Papers

We develop a new approach to combinatorial games that reveals connections between such games and some of the central ideas of nonlinear dynamics: scaling behaviors, complex dynamics and chaos, universality, and aggregation processes. We take as our model system the combinatorial game Chomp, which is one of the simplest in a class of "unsolved" combinatorial games that includes Chess, Checkers, and Go. We discover that the game possesses an underlying geometric structure that "grows" (reminiscent of crystal growth), and show how this growth can be analyzed using a renormalization procedure adapted from physics. In effect, this methodology allows one to …

An Investigation Of Introductory Physics Students’ Approaches To Problem Solving, Laura Walsh, Robert Howard, Brian Bowe

Articles

This paper outlines ongoing research investigating students’ approaches to quantitative and qualitative problem solving in physics. This is an empirical study, which was conducted using a phenomenographic approach to analyse and interpret data from individual semi-structured interviews with students from introductory physics courses. The result of the study thus far is a preliminary set of hierarchical categories that describe the students’ problem-solving approaches when faced with various physics problems. The findings from the research presented here indicate that many introductory students in higher education do not approach problem solving in a strategic manner and many do not try to link …

A Cross-Cultural, Multilevel Study Of Inquiry-Based Instruction Effects On Conceptual Understanding And Motivation In Physics, Meiko Negishi

Theses and Dissertations

Student achievement and motivation to learn physics is highly valued in many industrialized countries including the United States and Japan. Science education curricula in these countries emphasize the importance and encourage classroom teachers to use an inquiry approach. This dissertation investigated high school students? motivational orientations and their understanding of physics concepts in a context of inquiry-based instruction. The goals were to explore the patterns of instructional effects on motivation and learning in each country and to examine cultural differences and similarities. Participants consisted of 108 students (55 females, 53 males) and 9 physics teachers in the United States and …

Determining The Agn Fraction Of Galaxy Groups, Rachel Paterno-Mahler

Pomona Senior Theses

Using the Chandra X-ray Observatory, Martini et al. (2006) found that the AGN fraction of galaxy clusters was five times higher than previous optical studies suggested. Using visual observations only, Dressler et al. (1985) estimated the AGN fraction of field galaxies to be 5%, while that of clusters was thought to be 1%. To understand the role that the environment plays in AGN fueling, the author studied a variety of environments, ranging from the field to groups to clusters. Will the AGN fraction of groups also be higher than that of the field? The author demonstrates how the AGN fraction …

Fuzzy Blackholes, Anand Murugan

Pomona Senior Theses

The fuzzball model of a black hole is an attempt to resolve the many paradoxes and puzzles of black hole physics that have revealed themselves over the last century. These badly behaved solutions of general relativity have given physicists one of the few laboratories to test candidate quantum theories of gravity. Though little is known about exactly what lies beyond the event horizon, and what the ultimate fate of matter that falls in to a black hole is, we know a few intriguing and elegant semi-classical results that have kept physicists occupied. Among these are the known black hole entropy …

Velocity Half-Sphere Model For Multiple Scattering In A Semi-Infinite Medium, S Menon, Q Su, Rainer Grobe

Faculty publications – Physics

We show how the velocity half-sphere model [S. Menon, Q. Su, and R. Grobe, Phys. Rev. E 72, 041910 (2005)] recently introduced to predict the propagation of light for an infinite turbid medium can be extended to account for the emission of multiply scattered light for a geometry with a planar boundary. A comparison with exact solutions obtained from Monte Carlo simulations suggests that this approach can improve the predictions of the usual diffusion theory for both isotropic and highly forward scattering media with reflecting interfaces.

Coupling Down Converted Light Into Single Mode Fibers, David A. Niemi

Theses and Dissertations

We investigate the influence of the pump and collection mode parameters on the collection efficiency of Type I down converted photons into single mode fibers. For best single and coincidence counting rates, we find that the mode sizes should be close to the same size and that the mode waists should be located near the down-conversion crystal. Larger collection waists give higher collection efficiencies, but lower singles counts.

On The (In)Consistency Of Aristotle's Philosophy Of Time, Tiberiu Popa

The Society for Ancient Greek Philosophy Newsletter

Aristotle’s mind-dependence theory of time is considerably more than an eccentric afterthought formulated in a short passage, as many believe; rather, it is firmly anchored in Physics IV, especially in Ch. 11. A number of formulations that may seem purely epistemic or propaedeutic in nature do in fact have ontological significance, pointing to the fact that time’s existence hinges crucially on our capacity to perceive change. Aristotle seems to be echoed in crucial respects by contemporary theories of time, notably by A. Grünbaum’s.

Physics Alumni Newsletter Spring 2007, Terry Goforth

Physics Alumni Newsletter

Physics Alumni Newsletter

The Physics Alumni Newsletter is produced by the SWOSU Physics Department.

Our Engineering Physics students are recruited in fields such as electronics, aerospace, mechanical engineering, petroleum engineering and software engineering. Graduates also have careers in meteorology, architecture, education and more.

Nonlocal Entanglement Of Coherent States, Complementarity, And Quantum Erasure, Christopher C. Gerry, Rainer Grobe

Faculty publications – Physics

We describe a nonlocal method for generating entangled coherent states of a two-mode field wherein the field modes never meet. The proposed method is an extension of an earlier proposal [C. C. Gerry, Phys. Rev. A 59, 4095 (1999)] for the generation of superpositions of coherent states. A single photon injected into a Mach-Zehnder interferometer with cross-Kerr media in both arms coupling with two external fields in coherent states produces entangled coherent states upon detection at one of the output ports. We point out that our proposal can be alternatively viewed as a "which path" experiment, and in the case …

Radiation-Induced Current In Quantum Wires With Side-Coupled Nanorings, Yuriy V. Pershin Dr, Carlo Piermarocchi

Faculty Publications

Photocurrent generation is studied in a system composed of a quantum wire with side-coupled quantum rings. The current generation results from the interplay of the particular geometry of the system and the use of circularly polarized radiation. We study the energy-momentum conservation for optical transitions involving electrons moving forward and backwards in the wire. Due to the lack of time-reversal symmetry in the radiation, the optical transitions depend on the direction of motion of the electrons, leading to a current at zero bias voltage. The photocurrent increases with the number of rings within a wide range of physical parameters. A …

Neutron Interferometric Method To Provide Improved Constraints On Non-Newtonian Gravity At The Nanometer Scale, Geoffrey L. Greene, Vladimir Gudkov

Faculty Publications

In recent years, an energetic experimental program has set quite stringent limits on a possible “non-1/r²” dependence on gravity at short length scales. This effort has been largely driven by the predictions of theories based on compactification of extra spatial dimensions. It is characteristic of many such theories that the strength and length scales of such anomalous gravity are not clearly determined from first principles. As a result, it is productive to extend the current limits the range and strength of such hypothetical interactions. As a heavy, neutral, and (almost) stable particle, the neutron provides an ideal probe …

The Equation, Winter 2007, College Of Science And Mathematics, Wright State University

College of Science and Mathematics Newsletters

This 26 page newsletter discusses various happenings within the College of Science and Mathematics. It begins with a letter from the dean, and continues on with news, events, alumni news, and other community news.

Reissner–Nordstrom Expansion, Emil Prodanov, Rossen Ivanov, Vesselin Gueorguiev

Articles

We propose a classical mechanism for the cosmic expansion during the radiation-dominated era, assuming the Universe as a two-component gas. The first component is the ultra-relativistic “standard” fraction described by an equation of state of an ideal quantum gas of massless particles. The second component consist of superheavy charged particles and their interaction with the “standard” fraction drives the expansion. This interaction is described by the Reissner–Nordstr¨om metric purely geometrically — the superheavy charged particles are modeled as zero-dimensional naked singularities which exhibit gravitational repulsion. The radius of a repulsive sphere, surrounding a naked singularity of charge Q, is inversely …

Synecdoche And Surprise: Transdisciplinary Knowledge Production, Anne Dalke, Elizabeth Mccormack

Literatures in English Faculty Research and Scholarship

Using contemporary insights from feminist critical theory and the literary device of synecdoche, we argue that transdisciplinary knowledge is productive because it maximizes serendipity. We draw on student learning experiences in a course on “Gender and Science” to illustrate how the dichotomous frameworks and part-whole correspondences that are predominant in much disciplinary discourse must be dismantled for innovative intellectual work to take place. In such a process, disciplinary presumptions interrogate and unsettle one another to produce novel questions and answers.

Cascade Production In The Reactions 𝛾p → K⁺ K⁺(X) And 𝛾p → K⁺K⁺ Π⁻⁻(X), M. J. Amaryan, H. Bagdasaryan, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde-Wright, N. Kalantarians, A. Klein, S. E. Kuhn, M. R. Niroula, S. Tkachenko, L. B. Weinstein, J. Zhang, Et Al., Clas Collaboration

Physics Faculty Publications

Photoproduction of the cascade resonances has been investigated in the reactions γp → K + K +(X) and γp → K + K + π −(X). The mass splitting of the ground state (Ξ⁻,Ξ⁰) doublet is measured to be 5.4 ± 1.8 MeV/c², consistent with existing measurements. The differential (total) cross sections for the Ξ⁻ have been determined for photon beam energies from 2.75 to 3.85 (4.75) GeV and are consistent with a production mechanism of Y∗→K+Ξ⁻ through a t-channel process. The reaction γp→K+K+π−[Ξ⁰] has also been investigated to …

Erratum: Cross Sections For The 𝛾p -> K*⁰ Σ⁺ Reaction At E𝛾 = 1.7-3.0 Gev (Physical Review C. 75, 042201), M. Amarian, H. Bagdasaryan, S. Bültmann, G. E. Dodge, G. Gavalian, C. E. Hyde-Wright, A. Klein, S. E. Kuhn, F. Sabatié, L. B. Weinstein, Et. Al., The Clas Collaboration

Physics Faculty Publications

No abstract provided.

Cross Sections For The 𝛾p -> K*⁰ Σ⁺ Reaction At E𝛾 = 1.7-3.0 Gev, M. Amarian, H. Bagdasaryan, S. Bültmann, S. L. Careccia, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde-Wright, A. Klein, A. V. Klimenko, S. E. Kuhn, M. R. Niroula, S. Tkachenko, L. B. Weinstein, J. Zhang, Et Al., The Clas Collaboration

Physics Faculty Publications

Differential cross sections for the reaction 𝛾p→ K*⁰Σ+ are presented in the photon energy range of 1.7 to 3.0 GeV. The K^*0 was detected by its decay products, K⁺π⁻, in the Continuous Electron Beam Accelerator Facility's large acceptance spectrometer (CLAS) detector at the Thomas Jefferson National Accelerator Facility. These data are the first K^*0 photoproduction cross sections ever published over a broad range of angles. Comparison with a theoretical model based on the vector and tensor K^∗-quark couplings shows good agreement with the data, except at forward angles, suggesting that …

Experimental Study Of Exclusive ²H(E,E'P)N Reaction Mechanisms At High Q², S. E. Kuhn, M. J. Amaryan, H. Bagdasaryan, M. Bektasoglu, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, N. Guler, C. E. Hyde-Wright, H. G. Juengst, N. Kalantarians, A. Klein, M. R. Niroula, R. A. Niyazov, S. Tkachenko, L. B. Weinstein, J. Zhang, Et. Al., Clas Collaboration

Physics Faculty Publications

The reaction ²H(e,e(')p)n has been studied with full kinematic coverage for photon virtuality 1.75 < Q²< 5.5 GeV². Comparisons of experimental data with theory indicate that for very low values of neutron recoil momentum (p_n< 100 MeV/c) the neutron is primarily a spectator and the reaction can be described by the plane-wave impulse approximation. For 100 < p_n< 750 MeV/c, proton-neutron rescattering dominates the cross section, while Delta production followed by the NΔ → NN transition is the primary contribution at higher momenta.

A Descriptive Framework For The Problem-Solving Experiences Of Physics Students, Sherry Savrda

Electronic Theses and Dissertations

This study investigated the applicability of a general model of physics students' problem-solving experiences that suggests there are four dynamic factors affecting the problem-solving process: categorization, goal interpretation, resource relevance, and complexity. Furthermore, it suggests an overarching control factor called stabilization, which describes the inter-relatedness of the other factors over the problem-solving process. Think-aloud protocols of problem-solving experiences were used to investigate the model. Results of the study showed that conceptual resources had a significant impact on the success of problem-solving attempts. Participants who exhibited a lack of understanding of physics concepts were less likely to check their work, use …

Kaon Nucleon Scattering In Lattice Qcd, Anthony Charles Marcolongo

Master's Theses and Capstones

In this paper I discuss why one would want to study meson baryon interactions within the framework of lattice QCD, and what I have contributed to this area of research. I begin with a little background on QCD, and Chiral theories. I analyze Kaon Nucleon scattering, and calculate the Kaon Nucleon scattering length from data obtained using a lattice QCD simulation. Therefore, I show that it is possible to use Lattice QCD simulation to extract observables. This is important in areas where experiments are challenging or impossible with current technologies.

Improving High School Physical Science Students' Understanding Of The Electromagnetic Spectrum: A Modified Diagram Approach, James Edward Quebedeaux

LSU Doctoral Dissertations

The focus of this study was to identify major conceptual difficulties that selected public high school physical science students encounter in understanding a standard electromagnetic spectrum diagram. A research-driven, modified version of that standard diagram was used in this study to determine the value added to student understanding of electromagnetic waves. A content analysis was performed on electromagnetic spectrum diagrams found in US textbooks from the 1950s through the present. A class of public high school physical science students participated in a study consisting of four activities conducted during a three-week unit. Students were given a pre- and post-achievement test …

Strongly And Weakly Directed Approaches To Teaching Multiple Representation Use In Physics, Patrick B. Kohl, David Rosengrant, Noah D. Finkelstein

Faculty Articles

Good use of multiple representations is considered key to learning physics, and so there is considerable motivation both to learn how students use multiple representations when solving problems and to learn how best to teach problem solving using multiple representations. In this study of two large-lecture algebra-based physics courses at the University of Colorado (CU) and Rutgers, the State University of New Jersey, we address both issues. Students in each of the two courses solved five common electrostatics problems of varying difficulty, and we examine their solutions to clarify the relationship between multiple representation use and performance on problems involving …

Using Power Spectra To Look For Anisotropies In Ultra-High Energy Cosmic Ray Distributions, Megan Alicia Mcewen

LSU Doctoral Dissertations

The origins and compositions of ultra-high energy cosmic rays (UHECR) remains a mystery to this day. The Pierre Auger Observatory (PAO) is being constructed now in the hopes that it will help solve this mystery by detecting more UHECR than any previous experiment. In this dissertation, I will discuss this experiment, and analyze the data collected so far by comparing it with simulated data from possible source distributions. In these simulations, I will track antiprotons, along with other possible cosmic ray primaries, through various models of galactic and extragalactic magnetic fields. Once they reach a certain distance, I will record …

Small-Scale Structures In Three-Dimensional Magnetohydrodynamic Turbulence, P. D. Mininni, A. G. Pouquet, D. C. Montgomery

Dartmouth Scholarship

We investigate using direct numerical simulations with grids up to 15363 points, the rate at which small scales develop in a decaying three-dimensional MHD flow both for deterministic and random initial conditions. Parallel current and vorticity sheets form at the same spatial locations, and further destabilize and fold or roll up after an initial exponential phase. At high Reynolds numbers, a self-similar evolution of the current and vorticity maxima is found, in which they grow as a cubic power of time; the flow then reaches a finite dissipation rate independent of the Reynolds number.

Theory Of Cavity-Polariton Self-Trapping And Optical Strain In Polymer Chains, M. V. Katkov, Yuriy V. Pershin Dr, C. Piermarocchi

Faculty Publications

We consider a semiconductor polymer chain coupled to a single electromagnetic mode in a cavity. The excitations of the chain have a mixed exciton-photon character and are described as polaritons. Polaritons are coupled to the lattice by the deformation potential interaction and can propagate in the chain. We find that the presence of optical excitation in the polymer induces strain on the lattice. We use a BCS variational wave function to calculate the chemical potential of the polaritons as a function of their density. We analyze first the case of a short chain with only two unit cells in order …

Casimir Forces And Non-Newtonian Gravitation, Roberto Onofrio

Dartmouth Scholarship

The search for non-relativistic deviations from Newtonian gravitation can lead to new phenomena signalling the unification of gravity with the other fundamental interactions. Various recent theoretical frameworks indicate a possible window for non-Newtonian forces with gravitational coupling strength in the micrometre range. The major expected background in the same range is attributable to the Casimir force or variants of it if dielectric materials, rather than conducting ones, are considered. Here we review the measurements of the Casimir force performed so far in the micrometre range and how they determine constraints on non-Newtonian gravitation, also discussing the dominant sources of false …

A Simple Electric Field Probe In A Gauss's Law Laboratory, Daniel O. Ludwigsen, Gregory N. Hassold

Physics Publications

Early in our calculus-based introductory course, students are introduced to electric fields and sometimes struggle with the abstraction of a vector field. They have less familiarity with the phenomena associated with electric fields, and the connection between phenomena and mathematical formalism is weaker. Our very next topic is Gauss's law.