Bulletin of the American Physical Society
APS April Meeting 2012
Volume 57, Number 3
Saturday–Tuesday, March 31–April 3 2012; Atlanta, Georgia
Session C15: SPS Undergraduate Research, Education, and Outreach II |
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Sponsoring Units: FEd Chair: Gary White, Society of Physics Students, American Institute of Physics Room: Grand Hall East D |
Saturday, March 31, 2012 1:30PM - 1:42PM |
C15.00001: Rutherford's Nuclear World Fidele Bingwa The goals of the Center for History of Physics at the American Institute of Physics (AIP) are to preserve and make known the historical record of modern physics and allied science. 2011 marked the 100th anniversary of the discovery of the atomic Nucleus by Lord Rutherford which is why Center for History of Physics decided to create the ``Rutherford's Nuclear World'' web exhibit. Lord Rutherford was a great scientist and he is considered the father of Nuclear Physics. My research for the web exhibit focused on Lord Rutherford's early life and his time as director of the Cavendish Laboratory. For most scientific breakthroughs, only the scientists' names and the time of the breakthroughs seem to matter. The goal of my research was to put stories behind Rutherford's scientific discoveries, to know what was the atmosphere in his lab, what was going on in his personal life before and after the discovery, and also to understand the man he was by looking back at his early life, and the journey that made him one of the elites. All the information found during the research came from the resources of the Niels Bohr Library which include microfilms of Lord Rutherford's correspondence, oral history interviews of his closest collaborators, books written by his students and biographers, and pictures from the visual archives. The exhibit will highlight the importance of education in Rutherford's upbringing, his passion and enthusiasm for research, his scientific insight, his warm personality that made him a great educator, friend, and mentor. In addition, the exhibit, through Rutherford's interactions with fellow scientists, offers a unique perspective of the early 20$^{th}$ century scientific community. [Preview Abstract] |
Saturday, March 31, 2012 1:42PM - 1:54PM |
C15.00002: Making Time for Spacetime: The Story of a National Science Cafe Effort Kendra Redmond, Anish Chakrabarti Science Cafes are live and lively events that take place in casual settings such as coffeehouses or bars, are open to everyone, and feature an engaging conversation with a scientist about a compelling scientific topic. The Science Cafe movement in the United States is a grassroots effort to really engage the public in discussions about science and its relevance to society, inspired by the United Kingdom Cafe Scientifique organization. With support from NOVA and the related website sciencecafes.org, a number of Society of Physics Students chapters hosted local Cosmic Cafes (cosmic themed science cafes) in late 2011 and early 2012. This presentation will discuss the goals and models of the Science Cafe movement, the Cosmic Cafe effort, lessons learned, and how you can get involved. [Preview Abstract] |
Saturday, March 31, 2012 1:54PM - 2:06PM |
C15.00003: Shaping the Brown Dwarf Desert: Predicting the Primordial Brown Dwarf Binary Distributions from Turbulent Fragmentation Peter Jumper, Robert Fisher Brown dwarfs are failed stars, with masses too low to undergo hydrogen nuclear burning. While the first incontrovertible brown dwarf was detected observationally in 1995, their formation mechanism and the origin of many of their physical properties remain open questions. The absence of brown dwarf companions in close orbits (less than several AU) to solar-type primary stars in binary systems poses a major problem. Astronomers have termed this sparsity of nearby brown dwarf companions in binary systems the brown dwarf desert. We demonstrate that direct fragmentation of the parent gaseous turbulent giant molecular cloud cores naturally gives rise to widely-separated stellar-brown dwarf binary systems. We also show that this fragmentation produces narrowly-separated brown dwarf - brown dwarf binary systems. Additionally, these results support the observation that the minimum binding energy of systems increases with decreasing system mass. [Preview Abstract] |
Saturday, March 31, 2012 2:06PM - 2:18PM |
C15.00004: A Semi-Analytic Model of a Buoyant Flame Bubble Propagation During the Deflagration Phase of a Type Ia Supernova Kevin Jumper, Robert Fisher Type Ia supernovae are astronomical events in which a white dwarf, the cold remnant of a star that has exhausted its hydrogen fuel, detonates and briefly produces an explosion brighter than most galaxies. Many researchers think that they could occur as the white dwarf approaches a critical mass of 1.4 solar masses by accreting matter from a companion main sequence star, a scenario that is referred to as the single-degenerate channel. Assuming such a progenitor, we construct a semi-analytic model of the propagation of a flame bubble ignited at a single off-center point within the white dwarf. The bubble then rises under the influences of buoyancy and drag, burning the surrounding fuel material in a process called deflagration. We contrast the behavior of the deflagration phase in the presence of a physically high Reynolds number regime with the low Reynolds number regimes inherent to three-dimensional simulations, which are a consequence of numerical viscosity. Our work may help validate three-dimensional deflagration results over a range of initial conditions. [Preview Abstract] |
Saturday, March 31, 2012 2:18PM - 2:30PM |
C15.00005: Variational symmetries and conservation laws of the coupled Maxwell-Dirac equations Jackson Fliss, Balraj Menon The role of symmetry groups has become increasing important in the study of modern physics. The theorems of Emmy Noether link conservation laws to symmetries of the action functional. Contact symmetries can be constructed from the invariance of the action under infinitesimal transformations that are dependent on the independent variables and the dependent variables. First-order generalized symmetries can be constructed by including the first derivatives of the dependent variables. In the case of the coupled Maxwell-Dirac equations, the independent variables and dependent variables are, respectively, the spacetime coordinates and the fields. In this talk I will review the familiar symmetries of field theory, as well as investigate the first-order generalized symmetries of the coupled Maxwell-Dirac equations. The local conservation laws associated with each of these, via the theorems of Noether, will be addressed as well. [Preview Abstract] |
Saturday, March 31, 2012 2:30PM - 2:42PM |
C15.00006: Molecular Dynamics Simulations to Explore the Effects of Si-C Chemistry in 20-keV C60 Bombardment of Si Clarissa Briner, Kristin Krantzman C$_{60}$ ion beams have been successful for high resolution sputter depth profiling of metallic multilayer structures. However, in experiments of C$_{60}^+$ bombardment of Si, unusual effects are observed, which are thought to be due to the strong covalent bonds that can be formed between C atoms from the projectile and Si atoms from the substrate. Similar effects have been observed in experiments on organic materials with C$_{60}^+$ projectile. We have adopted a recently developed scheme to model multi-impact bombardment of C$_{60}$ on a single Si surface. Recent experiments have shown that C atoms are primarily ejected in the form Si$_3$C$^+$, a result which has led the authors to conclude that C atoms from the projectile are incorporated into the substrate by bonding to three neighboring Si atoms. We present the results of molecular dynamics (MD) simulations to model cumulative effects of successive C$_{60}$ bombardment. Analysis has been done on composition of sputtered clusters, cluster ejection mechanisms, and surface composition by layer depth. [Preview Abstract] |
Saturday, March 31, 2012 2:42PM - 2:54PM |
C15.00007: AFM and SThM Characterization of Graphene Christopher Foy, Anton Sidorov, Xunchi Chen, Ming Ruan, Claire Berger, Walter de Heer, Zhigang Jiang We report on detailed characterization of epitaxial grown graphene on SiC and chemical vapor deposition grown graphene on Cu foil using atomic force microscopy (AFM) and scanning thermal microscopy (SThM). We focus on the electronic and thermal properties of graphene grain boundaries, and thus providing valuable feedback to materials growth. Specifically, we perform thermal conductivity contrast mapping and surface potential mapping of graphene, and compare with that obtained on the Au electrodes and the substrate. [Preview Abstract] |
Saturday, March 31, 2012 2:54PM - 3:06PM |
C15.00008: A Connection between Geometrical Optics and an Elementary Kinematics Experiment Nelson Zamorano, Luis Argomedo, Ricardo Henriquez Using an old device like the rail and a steel ball, we propose to show the students a connection between the kinematic of a ball with a constant speed and the trajectory of a light ray going between two points located at different media separated by a flat interface. Releasing the ball from two different heights, the students, using a free software, obtain two graphs of position vs. time. With this information, they have to set another graph. First they must draw five (for instance) different paths for going from the point in medium 1 to the other in medium 2. Next, they must compute the time it takes to cover the distance between the two points chosen at initio for the different paths, using only a ruler and the data from the kinematics graph. From this exercise the students learn that the straight line is the shortest in distance but not in travelling time. With elementary trigonometry they arrive to the rules for the geometrical optics. The experiment should end with a display a real light ray travelling along different media. There are other applications, in a different context, that can be used with this structure. This experiment is, in our opinion, a good practice for the use of graphs and the handling of information. They also learn about elementary path integrals. [Preview Abstract] |
Saturday, March 31, 2012 3:06PM - 3:18PM |
C15.00009: Teaching Online: An Integrated Approach Christian Thomas Teaching online is becoming more popular and many web-based tools are available for both traditional and online courses. Web applets, videos, hi-resolution images, \&c.\ are available to illustrate and reinforce content. Most are generally used as separate material in the classroom or from a separate web page, not tied directly to the course text. Web pages amalgamate resources based on topics, but are generally not directly linked to the material covered in a textbook. Some textbooks come with separate CDROMs containing extra materials, but these are an add-on. I will present an example of an integrated course text with materials linked directly into the text. This method allows students to look at the illustration at the appropriate time --- when it is relevant to the material they are reading. I will also discuss the benefits of using these materials in an introductory astronomy course. [Preview Abstract] |
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