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Nykl, Scott L.High-fidelity Distributed Physics for Continuous Interactive Virtual Worlds Using Server Clusters
Master of Science (MS), Ohio University, 2008, Computer Science (Engineering and Technology)
Today's virtual worlds are places of immense interaction and realism that give rise to highly immersive environments. One of the most critical aspects providing this realism is the simulation of motion and the physical interaction between objects, i.e., physics. The physics of a virtual world is governed by mathematical equations that approximate the physical attributes of the real world. As virtual worlds grow larger, the computational complexity grows; thus, the processing time needed to simulate the virtual world grows. Once the processing time required to simulate an amount of time within the virtual world is greater than that same time in the real world, players in the virtual world begin to notice a slow down; this takes away from realism and causes immersion to suffer. As virtual worlds grow larger and more complex, the computational power required to simulate the virtual world in ‘real time' grows proportionally. This thesis focuses on simulating high fidelity distributed physics for continuous interactive virtual worlds using server clusters.

Committee:

David M. Chelberg, PhD (Advisor); Shawn Ostermann, PhD (Committee Member); Hans Kruse, PhD (Committee Member); Teresa Franklin, PhD (Committee Member)

Subjects:

Computer Science

Keywords:

physics; distributed physics; distributed game engine; game physics using server clusters; simulated physics using server clusters; distributed game engine using server clusters; MMO; virtual worlds; MMO physics; distributed physics for MMOs

Mithani, Murad A.The Development and Marketing of an Online Guided Study Program for the GRE Physics Exam Towards an Understanding of Future Instructional Methodologies
Master of Sciences, Case Western Reserve University, 2008, Physics
Online Distance Learning has made it possible to use a large set of training resources customized to the users and the environment. The study identifies an effective approach for the development and marketing of a GRE physics online guided study program based on the available literature and the experience and materials developed by Professor Robert Brown at Case Western Reserve University. The findings conclude that the approach is cost‐effective for the student, will serve approximately 30% of the 12,500 GRE physics candidates every year and will generate an annual income of $80,000 if continued as a university publishing project or more if transformed into an online training platform with multiple revenue streams. The program also serves as a proof of concept towards structuring future online instructional methodologies to position Case Western Reserve University and the Department of Physics at the forefront of learning technologies.

Committee:

Dr. Robert Brown (Advisor); Cyrus Taylor (Committee Member); Edward Caner (Committee Member)

Subjects:

Business Community; Business Costs; Education; Educational Software; Marketing; Mass Media; Physics; Science Education; Teaching

Keywords:

distance learning; online education; GRE physics; physics training; GRE marketing; future instructional methodologies; physics education; internet physics; physics marketing; ETS physics education; GRE multimedia mix

Langmack, Christian BishopUniversal Loss Processes in Bosonic Atoms with Positive Scattering Lengths
Doctor of Philosophy, The Ohio State University, 2013, Physics
In experiments with trapped ultracold gases, atoms can be lost through inelastic scattering processes. If the atoms have a scattering length that is much larger than the range of their interactions, then the system exhibits universal behavior that does not depend on details of their interactions. Dramatic enhancements in the loss rate are observed at special negative values of the scattering length for which there is a universal molecule at threshold. In some experiments, enhancements of the loss rate have also been observed at other positive values of the scattering length. A mechanism proposed to explain this enhancement is that the losses result from many collisions of an energetic diatomic molecule created by a 3-atom collision. In this thesis, I demonstrate the failure of this mechanism as a viable explanation of the enhancement seen at positive scattering length. I present an alternative explanation for these enhancements in experiments using a Bose-Einstein condensate of atoms. They result from inelastic scattering of universal diatomic molecules in a coexisting condensate of these molecules.

Committee:

Eric Braaten, Ph.D. (Advisor); Yuri Kovchegov, Ph.D. (Committee Member); Mohit Randeria, Ph.D. (Committee Member); Stanley Durkin, Ph.D. (Committee Member)

Subjects:

Atoms and Subatomic Particles; Condensed Matter Physics; Physics; Quantum Physics; Theoretical Physics

Keywords:

Universal Physics, Cold Atoms, Efimov Physics, Atomic Physics

Howard, Meredith E.The Joy of CEX: Sharpening the (t,3He) probe at 345 MeV for the charge-exchange knife drawer
Doctor of Philosophy, The Ohio State University, 2008, Physics

This data set represents the first step in a campaign of (t,3He) charge-exchange experiments at the National Superconducting Cyclotron Laboratory designed explicitly to measure Gamow-Teller strength distributions in the electron capture direction for stable medium-heavy atomic nuclei, with particular interest in reaching the nuclei in the pf-shell or masses up to A=112. The 115 MeV/nucleon secondary triton beam with an average intensity of 4×106 pps on 10 mg/cm2 thick target foils produces 3He that are measured in the focal plane detectors of the S800 magnetic spectrometer. From these data, the scattering angle of the tritons is reconstructed to within 7 mrad and the energy of the recoil nucleus is reconstructed to better then 250 keV. Since there is no comprehensive study of the (t,3He) probe for triton energies of 100-400 MeV/nucleon, this data is the first step in evaluating the advantages of extracting B(GT) from the (t,3He) probe over other hadronic probes.

The first target is a CD2 target used for calibrating cross section. This is the third measurement for the (t,3He) probe on 12C above 100 MeV/nucleon. The present 12C(t,3He) cross section for the 12B ground state (Jπ=1+) is lower than a previous measurement at the NSCL by more than one standard deviation in uncertainty but agrees with 12C(3He,t)12N.

This (t,3He) measurement for 24Mg, the second target, is the first above 100 MeV/nucleon. The B(GT) distribution for 24Na is extracted from differential cross sections as a function of residual nucleus excitation energy up to 7 MeV. For each peak in excitation energy, the differential cross section as a function of reconstructed scattering angle is extrapolated to zero degrees using angular distrubutions calculated with the distorted wave calculations from the code FOLD and transformed to q=0 zero momentum transfer. Uncertainties in the B(GT) include a calculation of interference to Jπ=1+ expected from ΔL=2, ΔS=1 reactions.

Comparisons of B(GT) distributions of 24Na with that of modern calculations using an improved interaction for the sd-shell space are discussed. In particular, a recently improved hamiltonian for the sd-shell model space is compared with the quarter-century-old USD interaction. The experimental measurements, both the present data and those of the competing charge-exchange probe (d,2He), are in good agreement with theoretical calculations.

As a result of this work, the NSCL has dramatically improved the availability of the secondary triton beam and the resolution for charge-exchange experiments and completed experiments for (t,3He) on several nuclei above A=45.

Committee:

Evan Sugarbaker (Advisor); Thomas Humanic (Committee Member); Terrence Walker (Committee Member); Linn Van Woerkom (Committee Member)

Subjects:

Nuclear Physics; Physics

Keywords:

charge exchange; nuclear physics; physics; astrophysics; experimental physics; CEX; Gamow-Teller; GT strength; NSCL; intermediate energy

Krygier, AndrewOn The Origin of Super-Hot Electrons in Intense Laser-Plasma Interactions
Doctor of Philosophy, The Ohio State University, 2013, Physics
This thesis investigates the ultraintense laser-plasma interaction. An experiment to measure the generation of relativistic electrons and positrons was performed at the Texas Petawatt laser which resulted in the observation of the highest known positron energies ever recorded. The positrons are created by the Bethe-Heitler process where an electron scatters and emits bremsstrahlung radiation which then interacts with an atomic nucleus and creates an electron-positron pair. The positron bunch is a useful diagnostic for understanding the laser-plasma interaction. Modeling results are also presented that describe the acceleration mechanism for the highest energy electrons which drive many important applications. A simple mechanism we call loop-injected direct acceleration that is found to be overwhelmingly dominant in the acceleration of super-hot electrons is discussed in detail.

Committee:

Richard Freeman (Advisor); Douglass Schumacher (Committee Member); Jay Gupta (Committee Member); Nandini Trivedi (Committee Member)

Subjects:

Physics

Keywords:

high energy density physics; plasma physics; physics; laser plasma interactions

Shan, KathyImproving Student Learning and Views of Physics in a Large Enrollment Introductory Physics Class
Doctor of Philosophy, University of Toledo, 2013, Curriculum and Instruction
Introductory physics courses often serve as gatekeepers for many scientific and engineering programs and, increasingly, colleges are relying on large, lecture formats for these courses. Many students, however, leave having learned very little physics and with poor views of the subject. In interactive engagement (IE), classroom activities encourage students to engage with each other and with physics concepts and to be actively involved in their own learning. These methods have been shown to be effective in introductory physics classes with small group recitations. This study examined student learning and views of physics in a large enrollment course that included IE methods with no separate, small-group recitations. In this study, a large, lecture-based course included activities that had students explaining their reasoning both verbally and in writing, revise their ideas about physics concepts, and apply their reasoning to various problems. The questions addressed were: (a) What do students learn about physics concepts and how does student learning in this course compare to that reported in the literature for students in a traditional course, (b) Do students’ views of physics change and how do students’ views of physics compare to that reported in the literature for students in a traditional course, and (c) Which of the instructional strategies contribute to student learning in this course. Data included: pre-post administration of the Force Concept Inventory (FCI), classroom exams during the term, pre-post administration of the Colorado Learning Attitudes About Science Survey (CLASS), and student work, interviews, and open-ended surveys. The average normalized gain (g =0.32) on the FCI falls within the medium-gain range as reported in the physics education literature, even though the average pre-test score was very low (30 percent) and this was the instructor’s first implementation of IE methods. Students’ views of physics remained relatively unchanged by instruction. Findings also indicate that the interaction of the instructional strategies together contributed to student learning. Based on these results, IE methods should be adopted in introductory physics classes, particularly in classes where students have low pre-test scores. It is also important to provide support for instructors new to IE strategies.

Committee:

Rebecca Schneider (Committee Chair); Charlene M. Czerniak (Committee Member); Karen Bjorkman (Committee Member); Mark Templin (Committee Member)

Subjects:

Curriculum Development; Education; Physics; Science Education

Keywords:

Physics Education; Physics; Education; Curriculum; Teaching; Learning

Demaree, Dedra NicoleToward understanding writing to learn in physics: investigating student writing
Doctor of Philosophy, The Ohio State University, 2006, Physics
It is received wisdom that writing in a discipline helps students learn the discipline. We show that evidence for effectiveness is anecdotal, and that little data-based material informs these prejudices. This thesis begins the process of scientific study of writing in the discipline, in specific, in physics, and creates means to judge whether such writing is effective. The studies culminating in this thesis are an aggressive start to addressing these complex questions. This thesis presents several studies aimed at understanding the correlation of writing and content, and tracking and characterizing student writing behaviors to see how they are impacted by writing in physics courses. It consists of four parts: summer and autumn 2005 focus on writing in introductory physics labs with and without explicit instruction, while winter and spring 2006 focus on tracking and analyzing student writing and revising behavior in Physics by Inquiry (PbI). In Summer and autumn we found little connection between writing activities and displayed content knowledge, though writing instruction seemed to positively impact students’ ability to explain the physics concepts. In winter and spring we found some writing behaviors exhibited by students were consistent with the literature, but the behaviors were not consistent through the quarter and there was no evidence that practice in writing impacted these behaviors. In spring quarter we used a novel tracking program developed at the Ohio State University allowing us to obtain much more data in a more ideal fashion than existing programs. With these related projects, we establish three main results. First, there is a need for quantitative studies of Writing to Learn, and in specific of Writing to Learn within physics. Second, we have also made progress in characterizing student behaviors in an effort to quantify the study of writing: the link between writing and learning content is not obvious, and we have shown that students may not even be learning to write through practice in the context of physics. Third, we have developed a valuable new tool, a novel program to track and analyze student writing, that supplies quantitative information about student writing.

Committee:

Gordon Aubrecht (Advisor)

Subjects:

Physics, General

Keywords:

physics education; physics education research; writing to learn; writing across the curriculum

Fabby, CarolReforming the introductory laboratory to impact scientific reasoning abilities
MS, University of Cincinnati, 2012, Arts and Sciences: Physics
Research indicates that students enter college with wide variations in scientific reasoning abilities, and it also suggests that students with formal reasoning patterns are more proficient learners. Unfortunately, these abilities are not impacted in the typical college course. In an effort to better target the development of scientific reasoning abilities of students in our introductory physics lab courses, we have revised the structure of the lab activities while maintaining the same topics and equipment we have been using for years in a more traditional lab setting. The changes enable students to become more involved in the actual design of the experiments and place more emphasis on student use of evidence-based reasoning. The challenges in implementing these curricular adjustments have been evaluated to understand the impact the changes have had on student development of scientific reasoning abilities.

Committee:

Kathleen Koenig, PhD (Committee Chair); Robert Endorf, PhD (Committee Member); Richard Gass, PhD (Committee Member); James Sullivan, MS (Committee Member)

Subjects:

Physics

Keywords:

introductory physics labs;scientific reasoning abilities;evidence-based reasoning;college physics labs;;;

Wells, Randall CAzimuthal Dependence of Pion Interferometry in Au+Au Collisions at a Center of Mass Energy of 130AGeV
Doctor of Philosophy, The Ohio State University, 2002, Physics

The study of two-pion Bose-Einstein correlations provides a tool to extract both spatial and dynamic information regarding the freeze-out configuration of the emission region created in heavy ion collisions. Noncentral heavy ion collisions are inherently spatially and dynamically anisotropic. The study of such collisions through the φ dependence of the HBT radii, Rij2 , relative to the event plane allows one to observe the source from all angles, leading to a richer description of the interplay between geometry and dynamics.

The initial heavy ion running of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory provided Au + Au collisions at 130GeV. The focus of the heavy ion program at RHIC is the search for a new state of strongly interacting matter, the quark gluon plasma (QGP). STAR is a large acceptance detector at RHIC with azimuthal symmetry, allowing the study of a large variety of observables on an event-by-event basis to provide a better characterization of the freeze-out conditions. The detector geometry for the first year’s data consisted of a time projection chamber (TPC) immersed in a 0.25T magnetic field oriented along the symmetry axis to provide identification of particles with transverse momenta pT ≥100MeV/c.

The focus of this dissertation is the study of the φ dependence of the transverse HBT radii from ππ and π+π+ correlations in non-central collisions. 2nd order oscillations are observed in all transverse radii (Ro2 (φ), Rs2 (φ), and Ros2 (φ)). The oscillations are found to be consistent in phase and magnitude to both RQMD and hydrodynamic predictions, yet both models (over)underpredict (Ro2)Rs2 whose relative size indicates a short emission time-scale. A modified blast wave prameterization is successful at reproducing a variety of observables at RHIC (i.e. particle spectra, v2 (pT), Rij2 (pT), and Ro,s,os2 (φ)) with a univeral set of freeze-out parmeters. The results describe a freeze-out geometry extended out-of-plane indicative of a short source life-time.

Committee:

Michael Lisa (Advisor)

Subjects:

Physics, Nuclear

Keywords:

Nuclear Physics; Azimuthal Pion Interferometry; Relativistic Heavy Ion Physics

Adair, Aaron MStudent Misconceptions about Newtonian Mechanics: Origins and Solutions through Changes to Instruction
Doctor of Philosophy, The Ohio State University, 2013, Physics
In order for Physics Education Research (PER) to achieve its goals of significant learning gains with efficient methods, it is necessary to figure out what are the sorts of pre-existing issues that students have prior to instruction and then to create teaching methods that are best able to overcome those problems. This makes it necessary to figure out what is the nature of student physics misconceptions—prior beliefs that are both at variance to Newtonian mechanics and also prevent a student from properly cognizing Newtonian concepts. To understand the prior beliefs of students, it is necessary to uncover their origins, which may allow instructors to take into account the sources for ideas of physics that are contrary to Newtonian mechanics understanding. That form of instruction must also induce the sorts of metacognitive processes that allow students to transition from their previous conceptions to Newtonian ones, let alone towards those of modern physics. In this paper, the notions of basic dynamics that are common among first-year college students are studied and compared with previous literature. In particular, an analysis of historical documents from antiquity up to the early modern period shows that these conceptions were rather widespread and consistent over thousands of years and in numerous cultural contexts. This is one of the only analyses in PER that considers the original languages of some of these texts, along with appropriate historical scholarship. Based on the consistent appearance of these misconceptions, a test and interview module was devised to help elucidate the feelings students have that may relate to fictitious forces. The test looked at one-dimensional motion and forces. The first part of the interview asked each student about their answers to the test questions, while the second part asked how students felt when undergoing three cases of constant acceleration in a car. We determined that students confabulated relative motion with the experience of force; students claim to feel a force in the direction of relative motion even when the actual force is in the opposite direction. The interview process also showed how students had both their intuitive sense of physics as well as Newtonian concepts from instruction, and how each model was activated could be influenced by questions from the interviewer. In order to investigate how changes to instructional method and pedagogy may affect students’ ability to overcome their non-Newtonian intuitions, an experimental lecturing series was devised that used individual voting machines (“clickers”) to increase class participation and dialog in a fashion that was more student-centered. The experimental section also had video recordings of the lectures as well as concept-based video homework solutions. The initial availability of the videos hindered early use, and overall students rarely used these additions. The clicker system also had technical issues due to the volume of students and an interface that was not streamlined. Nonetheless, the results showed the experimental section to have significantly greater learning gains (d > 0.5, p ~ 0.01), and we determined that this was most likely due to the clicker system.

Committee:

Lei Bao (Advisor); Andrew Heckler (Committee Member); Gordon Aubrecht (Committee Member); Samir Matuhr (Committee Member)

Subjects:

Education; Physics; Science Education; Science History

Keywords:

Physics Education Research; history of science; misconceptions; Newtonian physics; education; constructivism

Slaunwhite, Jason M.Search for the Higgs Boson Produced in Association with a W Boson at CDF Run II
Doctor of Philosophy, The Ohio State University, 2009, Physics
We present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions (pp̄W±Hℓνbb̄) at a center of mass energy of 1.96 TeV. WH candidate events have a signature of a single lepton (e±/µ±), missing transverse energy, and two jets. The search looks for candidate events in approximately 2.7 fb-1 of data recorded with the CDF II detector. The high transverse momentum (high-pT) lepton (electron or muon) in the events provides a distinct signature for triggering and most of the events in the dataset come from high-pT lepton triggers. Our analysis improves on prior searches by including events recorded on the Missing Transverse Energy (MET) plus 2 jets trigger with a lepton reconstructed as an isolated high-pT charged particle. We increase the sample purity by identifying (“tagging”) long-lived b-hadrons in jets. A neural network combines distinguishing kinematic information into a function optimized for WH sensitivity. The neural network output distributions are consistent with the standard model background expectations and we set limits upper limits on the rate of Higgs production. We set 95% confidence level upper limits on the WH production cross section times branching ratio for Higgs masses from 100 to 150 GeV/c2 and express our results as a ratio of the experimental limit to the theoretical Standard Model production rate. Our limits range from 3.6 (4.3 expected) to 61.1 (43.2 expected) for Higgs masses from 100 to 150 GeV/c2, respectively.

Committee:

Richard Hughes, PhD (Advisor); Brian Winer, PhD (Committee Member); Junko Shigemitsu, PhD (Committee Member); Johnston-Halperin Ezekeil, PhD (Committee Member)

Subjects:

Physics

Keywords:

higgs boson; w-higgs associated production; cdf; high-energy physics; high transverse momentum physics;

Qiu, LeiExploring 2D Metal-Insulator Transition in p-GaAs Quantum Well with High rs
Doctor of Philosophy, Case Western Reserve University, 2014, Physics
This thesis consists of four main parts. The first part introduces the history of the concept of a Wigner crystal and recent theoretical developments based on this concept, which mainly raises the idea of having intermediate phases near the boundary of the Wigner crystal-liquid transition. It also briefly introduces another long standing puzzle: 2D zero field metal-insulator transition. The second part studies the solid phase known as the “Wigner crystal” (WC) of two-dimensional holes observed in weak perpendicular magnetic field. Magnetoresistivity and thermodynamic compressibility in several densities and temperatures are measured and discussed. It strongly suggests that the metal-insulator transition should be closely related to the WC-liquid transition since the experimental phase diagram coins with theoretical phase diagram. The third part investigates the phase transition between observed the solid phase and liquid state. A new intermediate phase called a micro-emulsion phase is discovered. Its isotropic feature and response to disorder level are discussed. Finally, the fourth part introduces a new perspective, which is derived from the conclusions of the second and third part, towards the two-decade puzzle named the two dimensional metal-insulator transition (2D MIT). Scaling behavior of resistivity of dilute holes in GaAs quantum well on the insulating side of 2D MIT is found for the first time. Overall, our studies indicate the observation of a new WC phase at low magnetic field. Through studying its transition to liquid state, a new intermediate phase is identified. By applying the new perspective gained, the scaling of resistivity is observed and strongly suggests that the 2D MIT is a quantum phase transition of WC and micro-emulsion phases.

Committee:

Xuan Gao (Advisor); Jesse Berezovsky (Committee Member); Jie Shan (Committee Member); Harsh Mathur (Committee Member); Philip Feng (Committee Member)

Subjects:

Condensed Matter Physics; Experiments; Low Temperature Physics; Physics

Keywords:

Condensed matter physics; Low temperature physics; Strongly correlated electrons; GaAs quantum well; 2DHG; Wigner solid; Fermi liquid; Integer quantum Hall effect; Fractional quantum Hall effect; Micro-emulsion phases; 2D metal-insulator transition

Warnakulasooriya, RasilStudents' models in some topics of electricity & magnetism
Doctor of Philosophy, The Ohio State University, 2003, Physics
Model-based learning have been emphasized by many researchers. Furthermore, many theories have been put forward by researchers on how students reason. However, how the theories of reasoning are manifested within the context of electricity and magnetism and how to implement a model-based learning environment within such a context has not been the object of research. In this dissertation, we address the above two concerns. We probe students' reasoning through a model-based diagnostic instrument. The instrument consists of a set of related multiple-choice questions that can be categorized as belonging to the same conceptual domain. The contextual features of a set are also kept to a minimum. We find that students' responses are tied to the models they have constructed or construct on the spot when faced with novel situations. We find that the concepts such as electric fields and electric potentials exist as mere “definitions” and do not contribute to forming a set of working models, and as such the need for the use of such concepts cannot be easily recognized. We also find that students function within a set of procedural rules. Whether these rules are extended directly from familiar situations through analogies or lead to constructing a set of new rules is constrained by the underlying models and the context of the questions. Models also either exist or are constructed in ways that lead students to overlook the common sense reality of physical phenomena. We also find that the way questions are perceived and interpreted are dependent on the underlying models and that different models exist without conflicting with each other. Based on the above findings, we argue that students' reasoning is context specific and is sensitive to the way the learning has taken place. Thus, we suggest a recontexualization process as a specific model-based learning environment to help students learn electricity and magnetism. The step-by-step guidance through a series of such related questions would then elucidate the context within which concepts are introduced, the limitations of particular representations and the ontological demands required by the subject.

Committee:

Lei Bao (Advisor)

Keywords:

Physics Learning; Electricity and Magnetism; Physics Education

Mills, Mary ElizabethThe Effects of Single-Sex Education on the Self-Efficacy of College Students Taking Introductory Physics
Master of Science, Miami University, 2011, Physics
Previous research has shown that young women can benefit from taking their science classes in single-sex classrooms. Further, women's colleges produce a disproportionate number of female scientists. There is less research on the effect of single-sex education on young men. We investigated the effects of single-sex education on the self-efficacy of college physics students by surveying students at four colleges about their experience in their college physics class. The schools included two women's colleges, one men's college, and one coeducational college. Interviews were also conducted at three of the schools to get a better understanding and more personal view of the students at these schools. Results from the surveys show on average, women at women's colleges and men at coeducational colleges have the same self-efficacy, while men at men's colleges have a lower self-efficacy and women at coeducational colleges have the lowest self-efficacy. Data from the interviews support these results.

Committee:

Jennifer Blue, PhD (Advisor); Stephen Alexander, PhD (Committee Member); Beverley Taylor, PhD (Committee Member); Janet Hurn, MAT (Committee Member)

Subjects:

Education; Gender; Physics; Science Education

Keywords:

physics; single-sex education; women's colleges; men's colleges; single-sex colleges; physics education research; self-efficacy; coeducation

Wendt, Kyle AndrewAdvances in the Application of the Similarity Renormalization Group to Strongly Interacting Systems
Doctor of Philosophy, The Ohio State University, 2013, Physics
The Similarity Renormalization Group (SRG) as applied in nuclear physics is a tool to soften and decouple inter-nucleon interactions. The necessity for such a tool is generated by the strong coupling of high- and low-momentum degrees of freedom in modern precision interactions. In recent years the SRG have been used with great success in enhancing few (2-12) nucleon calculations, but there are still many open questions about the nature of the SRG, and how it affects chiral forces. This thesis focuses on three topics within the study of the SRG as it applies to nuclear few-body interactions, with a focus on nuclear forces from chiral effective field theory . The typical SRG applied to nuclear physics is the Trel-SRG, which uses the relative kinetic energy to generate a renormalizing flow. However, this generator explicitly violates criteria that ensure the SRG will decouple the interaction. Previous study of this generator found for a simple model that as the resolution is lowered past the momentum scales associated with a bound state, the Trel-SRG enhances coupling near the bound state whereas the classical Wegner generator completely decouples the bound state. In practice, this has not been an issue because the only two-body bound state is very shallow, and therefore well below the SRG softening scales. This study is extended to use leading order chiral effective field theory with large cutoffs to explore this decoupling. This builds in the same low energy physics while including spurious high energy details, including high energy bound states. The evolutions with Trel-SRG are compared to the evolution with Wegner's generator. During the decoupling process, the SRG can induce new non-local contributions to the interactions, which inhibits its application using Quantum Monte Carlo (QMC) methods. Separating out the non-local terms is numerically difficult. Instead an approximate separation is applied to Trel-SRG evolved interactions and the nature of the induced non-locality is studied in detail. In order to do this, a generalization of the Weinberg Eigenvalue analysis is developed and applied to test this separation in order to study how perturbative the non-local terms are relative to a non-perturbative treatment of the local terms. Further perturbative corrections to the local solutions are studied. Nucleons are composite objects and as such three-nucleon, four-nucleon, and many-nucleon irreducible forces are necessary. These few-body forces are inherent to chiral effective field where they are formed in a natural hierarchy where the two nucleon force is dominant, with the three-nucleon next in the hierarchy and so forth. Within the SRG framework, it is necessary to evolve these few body forces in a consistent manner. During this process, new many-body forces will be induced even if there were only two-body forces initially. The details of these few-body evolutions are sensitive to the manner in which the SRG flow equation is solved and a new method for solving the momentum space SRG flow equation is developed and applied to study N2LO chiral effective field theory forces in the triton system.

Committee:

Richard Furnstahl (Advisor); Robert Perry (Committee Member); Michael Lisa (Committee Member); Nandini Trivedi (Committee Member)

Subjects:

Nuclear Physics; Physics

Keywords:

Nuclear Physics; Similarity Renormalization Group; Renormalization Group; Many-Body; Few-Body; Physics; Nuclear Interactions

Bishara, FadyProspecting for New Physics in the Higgs and Flavor Sectors
PhD, University of Cincinnati, 2015, Arts and Sciences: Physics
We explore two directions in beyond the standard model physics: dark matter model building and probing new sources of CP violation. In dark matter model building, we consider two scenarios where the stability of dark matter derives from the flavor symmetries of the standard model. The first model contains a flavor singlet dark matter candidate whose couplings to the visible sector are proportional to the flavor breaking parameters. This leads to a metastable dark matter with TeV scale mediators. In the second model, we consider a fully gauged SU(3)3 flavor model with a flavor triplet dark matter. Consequently, the dark matter multiplet is charged while the standard model fields are neutral under a remnant Z3 which ensures dark matter stability. We show that a Dirac fermion dark matter with radiative splitting in the multiplet must have a mass in the range [0.5,5] TeV in order to satisfy all experimental constraints. We then turn our attention to Higgs portal dark matter and investigate the possibility of obtaining bounds on the up, down, and strange quark Yukawa couplings. If Higgs portal dark matter is discovered, we find that direct detection rates are insensitive to vanishing light quark Yukawa couplings. We then review flavor models and give the expected enhancement or suppression of the Yukawa couplings in those models. Finally, in the last two chapters, we develop techniques for probing CP violation in the Higgs coupling to photons and in rare radiative decays of B mesons. While theoretically clean, we find that these methods are not practical with current and planned detectors. However, these techniques can be useful with a dedicated detector (e.g., a gaseous TPC). In the case of radiative B meson decay B0

Committee:

Jure Zupan, Ph.D. (Committee Chair); Alexander Kagan, Ph.D. (Committee Member); Michael Ma, Ph.D. (Committee Member); Alan Schwartz, Ph.D. (Committee Member)

Subjects:

Theoretical Physics

Keywords:

Beyond the standard model;CP violation;Dark matter;Higgs physics;Flavor physics;Collider phenomenology

Regensburger, Joseph JamesSearch For Radiative Decays Of D0 Mesons At The Babar Detector
Doctor of Philosophy, The Ohio State University, 2008, Physics

I detail my work searching for the radiative decays of D0 mesons, e.g. D0 → φγ, within 381.7fb-1 of e+e data collected by the BABAR detector at the PEP-II asymmetric-energy e+e collider at SLAC from 1999-2006. Such decays are not well described under perturbative techniques typically used to estimate the frequency of decays under the Standard Model of Particle Physics (SM), and as such are valuable laboratories to investigate quantum chromodyanmics calculations (QCD). I specifically examine the Cabibbo-suppressed (CS) D0 → φγ decay as well as search for the yet unobserved Cabibbo-favored (CF) decay, D0 → K̅*0γ. I measure the branching fractions of each mode relative to the decay D0 → Kπ+ and find:

B(D0 → φγ) = (2.73 ± 0.30 ± 0.26) × 10-5

and

B(D0 → K̅*0γ) = (3.22 ± 0.20 ± 0.27) × 10-4

These results are preliminary and currently under review by the BABAR collaboration ahead of publication. In these expressions the first error is due to statistical sources and the second is due to systematic sources.

Committee:

Klaus Honscheid, PhD (Advisor); Richard Kass, PhD (Committee Member); Richard Furnstahl, PhD (Committee Member); Thomas Humanic, PhD (Committee Member); Roberto Rojas-Teran, PhD (Committee Member)

Subjects:

Physics

Keywords:

radiative decay; charm physics; particle physics; babar; rare decays; D0 Mesons

Crawford, George WilliamGraduate preparation of physics instructors for liberal arts colleges /
Doctor of Philosophy, The Ohio State University, 1960, Graduate School

Committee:

Not Provided (Other)

Subjects:

Physics

Keywords:

Teachers;Physics;Physics teachers

Feister, ScottEfficient Acceleration of Electrons by an Intense Laser and its Reflection
Doctor of Philosophy, The Ohio State University, 2016, Physics
Here I present an experimental, theoretical, and computational exploration of an extremely efficient scheme for laser-based acceleration of electrons. A series of experiments were performed at the Air Force Research Laboratory in Dayton, OH, to show that a high-repetition-rate short-pulse laser (3 mJ, 40 fs, 1 kHz) normally incident on a continuous water stream can accelerate electrons in the back-reflection spray with >1% laser-to-electron efficiency for electrons >120 keV, and with >MeV electron energies present in large number. Characterization of the accelerated electrons was followed by explorations of appropriate focal conditions, pre-plasma conditions, and laser-intensity parameters. These experiments show clear signatures of plasma instabilities, with substantial 3ω/2 and ω/2 optical harmonics detected concurrently with efficient electron acceleration. Particle-in-cell (PIC) simulations of high-intensity laser interactions are able to reproduce the electron energies and acceleration efficiencies, as well as plasma instabilities. Analysis of the simulations suggest that electrons are accelerated by a standing wave established between incident and reflected light, coupled with direct laser acceleration by reflected light. Using hydrodynamic simulations of the laser pre-pulse interaction as initial conditions for PIC simulations of the main-pulse interaction clarifies mechanisms by which experimental manipulation of pre-pulse has effectively determined electron-acceleration efficiency in the laboratory.

Committee:

Richard R. Freeman (Advisor); Linn D. Van Woerkom (Committee Member); Junko Shigemitsu (Committee Member); Michael Lisa (Committee Member)

Subjects:

Physics

Keywords:

electron acceleration; high-intensity lasers; laser-plasma accelerator; high energy density physics; HEDP; standing wave; direct laser acceleration; electron spectrum; MeV; Particle-in-cell; PIC; FLASH; hydrodynamic; simulation; plasma physics

Hetel, Iulian NicolaeQuantum Critical Behavior In The Superfluid Density Of High-Temperature Superconducting Thin Films
Doctor of Philosophy, The Ohio State University, 2008, Physics

A central question in the physics of high-temperature superconductors is how superconductivity is lost at the extreme ends of the superconducting phase diagram, underdoping and overdoping. When mobile holes are removed from optimally doped cuprates, the transition temperature TC and superfluid density nS(0) decrease in a surprisingly correlated fashion. I succeeded in producing and measuring homogeneous underdoped high-temperature superconducting films by partially substituting Ca+2 for Y+3 in YBa2Cu3O7-d films with reduced oxygen concentrations in the CuO chains.

I test the idea that the physics of underdoped cuprates is dominated by phase fluctuations by measuring the temperature dependence of superfluid density nS(T) and by changing the dimensionality of the system from 3D thick samples to 2D ultrathin films. Thick Y1-xCaxBa2Cu3O7-d films are in agreement with previous measurements of pure YBa2Cu3O7-d samples and do not show any 2D or 3D-XY critical regimes in the temperature dependence of superfluid density. Moreover, the transition temperature has a square-root dependence on absolute superfluid density at zero temperature, rather than showing the predicted linear dependence in the case of strong thermal phase fluctuations. When superfluid density is measured in underdoped 2D Y1-xCaxBa2Cu3O7-d films as thin as only 2 unit cells for all doping levels, nS(T) has a dramatic downturn consistent with a 2D vortex-antivortex pair unbinding transition and, at severe underdoping, TC is linearly proportional to nS(0). This dimensionality-dependent scaling relation is the result of quantum phase fluctuations that suppress superconductivity near a Quantum Critical Point at zero temperature. Further measurements in an additional family of high-temperature superconductors, La2-xSrxCuO4, are consistent with my results in underdoped Y1-xCaxBa2Cu3O7-d.

La2-xSrxCuO4, also provided the opportunity to study the other extreme end of the superconducting phase diagram. In the overdoped region, as carrier density increases, supefluid density and the transition temperature are both suppressed. While it still remains uncertain what produces this suppression, a plausible interpretation is that only a small fraction of the hole carriers contribute to the superfluid density and the pair breaking effects are so important that they destroy superconductivity.

Committee:

R. Lemberger Thomas, Dr. (Advisor); Klaus Honscheid, Dr. (Committee Member); R Sooryakumar, Dr. (Committee Member); Nandini Trivedi, Dr. (Committee Member)

Subjects:

Physics

Keywords:

Superconductivity; Condensed Matter Physics; Low Temperature Physics

Kang, DaekyoungEfimov Physics in Fermionic Lithium atoms
Doctor of Philosophy, The Ohio State University, 2011, Physics
Efimov physics refers to universal phenomena that are characterized by discrete scaling behavior in three-body systems consisting of particles that interact with a large scattering length. The most well-known example is Efimov trimers, a sequence of universal bound states that in the case of infinite scattering length have a geometric spectrum with an accumulation point at the three-particle threshold. Efimov physics is also manifested in scattering processes through log-periodic dependence on the collision energy or on the scattering length. In experiments with trapped ultracold gases, the most dramatic features associated with Efimov physics are resonant enhancements of loss rates from an Efimov trimer near a scattering threshold. This thesis presents studies of Efimov physics in the three lowest hyperfine states of fermionic Lithium-6 atoms. We calculate the spectrum of the Efimov trimers as a function of the magnetic field. We calculate the three-body recombination rate at threshold, which exhibits loss resonances and interference minima associated with Efimov physics. We also calculate the relaxation rate of diatomic molecules due to inelastic collision with an atom, which also exhibit loss resonances and local minima. We compare our results with experimental measurements using trapped ultracold gases of Lithium-6 atoms.

Committee:

Eric Braaten, PhD (Advisor); Richard Furnstahl, PhD (Committee Member); Mohit Randeria, PhD (Committee Member); Gregory Lafyatis, PhD (Committee Member)

Subjects:

Physics

Keywords:

Efimov physics; Ultracold atoms; few-body physics; universality; strongly interacting system

May, David B.How Are Learning Physics And Student Beliefs About Learning Physics Connected? Measuring Epistemological Self-Reflection In An Introductory Course And Investigating Its Relationship To Conceptual Learning
Doctor of Philosophy, The Ohio State University, 2002, Physics
To explore students’ epistemological beliefs in a variety of conceptual domains in physics, and in a specific and novel context of measurement, this Dissertation makes use of Weekly Reports, a class assignment in which students reflect in writing on what they learn each week and how they learn it. Reports were assigned to students in the introductory physics course for honors engineering majors at The Ohio State University in two successive years. The Weekly Reports of several students from the first year were analyzed for the kinds of epistemological beliefs exhibited therein, called epistemological self-reflection, and a coding scheme was developed for categorizing and quantifying this reflection. The connection between epistemological self-reflection and conceptual learning in physics seen in a pilot study was replicated in a larger study, in which the coded reflections from the Weekly Reports of thirty students were correlated with their conceptual learning gains. Although the total amount of epistemological self-reflection was not found to be related to conceptual gain, different kinds of epistemological self-reflection were. Describing learning physics concepts in terms of logical reasoning and making personal connections were positively correlated with gains; describing learning from authority figures or by observing phenomena without making inferences were negatively correlated. Linear regression equations were determined in order to quantify the effects on conceptual gain of specific ways of describing learning. In an experimental test of this model, the regression equations and the Weekly Report coding scheme developed from the first year’s data were used to predict the conceptual gains of thirty students from the second year. The prediction was unsuccessful, possibly because these students were not given as much feedback on their reflections as were the first-year students. These results show that epistemological beliefs are important factors affecting the conceptual learning of physics students. Also, getting students to reflect meaningfully on their knowledge and learning is difficult and requires consistent feedback. Research into the epistemological beliefs of physics students in different contexts and from different populations can help us develop more complete models of epistemological beliefs, and ultimately improve the conceptual and epistemological knowledge of all students.

Committee:

Gordon Aubrecht (Advisor)

Keywords:

epistemological beliefs; physics; conceptual understanding; reflection; Physics Education Research

Arms, Kregg E.Study of tau lepton decays to three charged hadrons and one neutral pion
Doctor of Philosophy, The Ohio State University, 2005, Physics
We report a study of τ lepton decays to three charged hadrons and a π0. We use (7.56 ± 0.15) fb-1 of data collected with the CLEO III detector at the Υ(4S) resonance, which corresponds to a total of (6.90 ± 0.14) × 106 τ-pairs. Using both a Ring Imaging Cherenkov (RICH) detector and measurement of specific ionization energy loss (dE/dx) for particle identification, we report the first observation of the decay τ-K-ωντ. We report the first statistically significant measurements of the branching fractions for τ-K- π+ π- π0 ντ (excluding K0), τ-K- K+ π- π0 ντ and the first published upper limit for τ-K- K+ K- π0 ντ. We also measure branching fractions for the decays, τ-h- ω ντ, τ- → π- ω ντ, τ-h- h+ h- π0 ντ, and τ- → π- π+ π- π0 ντ .

Committee:

K. Gan (Advisor)

Keywords:

particle physics; tau lepton; omega meson; high energy physics; cleo

Ng, Chun YuSeeking the Light in the Dark: Quests for Identifying Dark Matter
Doctor of Philosophy, The Ohio State University, 2016, Physics
The night sky is a beautiful display of stars and galaxies. We have come a long way to realize that they are made with substances that can be produced and studied on Earth. However, it has been discovered that those substances make up only 5% of the observable Universe, with the remaining 95% being mysterious substances called dark matter and dark energy, both of which have never been observed directly. Their nature is among the most profound questions in modern science, and unquestionably holds the key to the fundamentals of the Universe and laws of physics. In this dissertation, I discuss a series of papers related to studies of dark matter. I revisit the problem of dark matter annihilation in the extragalactic background radiation, and show that they are sensitive to the properties of the smallest dark matter halos. I show that the newly discovered high-energy astrophysical neutrinos can be used to test secret neutrino interactions through their propagation in the Cosmic Neutrino Background. I discuss how we use the Fermi-GBM to search for sterile neutrino dark matter in a region of parameter space that is not probed otherwise. I discuss a novel method for testing dark matter annihilation/decay signals with a line spectrum. Lastly, I discuss new and interesting results from gamma-ray observations of the Sun, and how this is related to future dark matter searches from the Sun.

Committee:

John Beacom, Professor (Advisor); Amy Connolly, Professor (Committee Member); Robert Perry, Professor (Committee Member); Todd Thompson, Professor (Committee Member)

Subjects:

Astronomy; Astrophysics; Physics

Keywords:

Dark matter, neutrinos, gamma rays, cosmic rays, astrophysics, particle physics, physics

Hughes, William RodneyA study of the use of computer simulated experiments in the physics classroom /
Doctor of Philosophy, The Ohio State University, 1973, Graduate School

Committee:

Not Provided (Other)

Subjects:

Education

Keywords:

Physics;Physics;Digital computer simulation

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