Bulletin of the American Physical Society
Joint Fall 2012 Meeting of the Texas Sections of the APS, AAPT, and Zone 13 of the SPS
Volume 57, Number 10
Thursday–Saturday, October 25–27, 2012; Lubbock, Texas
Session B2: SPS and Undergraduate Research |
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Chair: David W. Donnelly, Texas State University Room: Holiday Inn Towers University B |
Friday, October 26, 2012 10:30AM - 10:42AM |
B2.00001: The Utilization of HOPG based Graphene for a less costly and efficient replacement of platinum in Dye-Sensitized Solar Cells (DSC's) Matthew P. Pusko Dye-Sensitized Solar Cells (DSC) are also known as Graetzel cells after their inventor, Michael Graetzel, who invented them in 1991. DSCs are potential alternatives to the more conventional and expensive semiconductor p-n junction solar cells like silicon solar cells. In a Graetzel cell, light is absorbed by a sensitizing dye which is coupled to a wide band gap semiconductor (TiO2). Electric charges are liberated by the photon induced electron injection from the dye molecules into the conduction band of the semiconductor. The use of sensitizers in conjunction with the semiconductor oxide permits the absorption of a large portion of the terrestrial solar spectrum with near 10\% conversion efficiency. In the ``traditional'' DSC, platinum metal is used as one of the counter electrode materials. In our research, graphene of various forms (from HOPG in specific) is utilized instead of costly platinum to replace the counter-electrode in the DSC's. HOPG also known as Higly Oriented Pyrolitic Graphite is being used to dry deposit graphene layers onto glass or FTO. [Preview Abstract] |
Friday, October 26, 2012 10:42AM - 10:54AM |
B2.00002: Solution Processed Graphene for Utilization in Thin Films Jonathan Belew Solution processing of graphene offers a method for increasing the purity and uniformity of the deposited thin films. Solubility parameters are useful in preparing dispersions and have been employed successfully with CNTs. Applying solubility parameters and solution processing techniques to graphene provides an avenue for both higher purity samples and more uniform thin films. The various families of solvents have different solubility parameters and careful selection of these parameters will help the quality of dispersions. Vacuum filtration and density centrifugation allow for filtering of the material, while annealing films is known to fix defects and improve structure. Through filtration, film deposition, and thermal annealing, graphene thin films of higher purity and uniformity will lead to graphene thin films that have the theoretical properties closer to ideal single crystal graphene. These properties have major applications in the fields of solar power and organic light emitting diodes as transparent electrodes and electron donor material. [Preview Abstract] |
Friday, October 26, 2012 10:54AM - 11:06AM |
B2.00003: Programming Mathematica to find normal mode frequencies for a system with a large number of degrees of freedom Gregory Beuhler, Chris Murrell, Brett Caswell, Hunter Close Imagine a system of N masses alternating with N+1 springs in a line between two walls, with all motion constrained to the line. This system has N normal modes, each with its own frequency. Using only basic knowledge of programming principles, we developed a program in Mathematica that allowed us to generate the frequencies of these normal modes for any value of N, including large N. In this talk we present the specific strategy, structure, and products of the program. In particular, we defined a function for filling matrices and used nested loops to extract relevant data. In a companion talk, we present physical arguments for patterns we observed in the sets of frequencies. [Preview Abstract] |
Friday, October 26, 2012 11:06AM - 11:18AM |
B2.00004: Graphene Anode Organic Light Emitting Diode Collin Timmons The mechanical and electrical properties of graphene make it a preferred replacement for the rare metal Indium in transparent electrodes. Research into replacing indium tin oxide with graphene is being conducted at Stephen F. Austin State University. This talk will be an overview of the graphene anode OLED and the challenges of starting OLED research at SFA. [Preview Abstract] |
Friday, October 26, 2012 11:18AM - 11:30AM |
B2.00005: Using new graphics and physical arguments to make sense of frequencies of large-N normal mode systems Chris Murrell, Brett Caswell, Gregory Beuhler, Hunter Close Imagine a system of N masses alternating with N+1 springs in a line between two walls, with all motion constrained to the line. This system has N normal modes, each with its own frequency. In a companion talk, we present how we used Mathematica to generate the frequencies of these normal modes, no matter how large N is. In this talk, we describe patterns we found in the frequencies, we explain physically why these patterns should be expected, and we generalize our physical arguments to further abstract our understanding of symmetry. [Preview Abstract] |
Friday, October 26, 2012 11:30AM - 11:42AM |
B2.00006: Student Internships: a low-risk, high-yield learning experience Catherine Schiber Internships can be valuable in increasing confidence in learning new skills and techniques for real world research. I did a ten-week internship program at Oak Ridge National Laboratory (ORNL) for the Department of Energy (DOE) through the Science Undergrad Laboratory Internship (SULI) program. I was assigned to the Spallation Neutron Source (SNS) division, where I worked peripherally on an accelerator. Within SNS, I was in the Research Accelerator Division (RAD), which worked with the accelerator beam before it hit the target and spalled neutrons. The first part of my project involved collecting and managing a database of possible accelerator beam size changes by solving a pre-existing model. The second part was putting that database into an interpolation program. However, I had no programming experience, and therefore had to learn on the job. I learned Jython by reading books, doing online tutorials, and asking occasional questions. By the end of the project, I had written a program in both Jython and JRuby that included a graphic user interface (GUI) and customized error messages. Therefore, I encourage all students to partake in an internship, even if it is not in their field of expertise. [Preview Abstract] |
Friday, October 26, 2012 11:42AM - 11:54AM |
B2.00007: Investigations of High-energy Gamma Rays through Cherenkov Radiation in Atmosphere Jonathan Clark, John Sandy, Chris Cowden, Nural Akchurin High-energy gamma rays from various sources interact with the atmosphere resulting in electromagnetic showers. Relativistic charged particles from the core of electromagnetic showers emit Cherenkov radiation which is highly directional and polarized. The size, temporal properties, as well as polarization of the Cherenkov radiation incident on the earth's surface reveal some of the fundamental properties of an incident gamma ray. The GEANT4 simulation package is used to model the electromagnetic showers resultant from gamma rays interacting with the atmosphere. We later analyze the collected data to estimate the signal generated by Cherenkov photons by an array of photo-multiplier tubes (PMTs). Our goal is to explore the feasibility of using the Cherenkov polarization information to improve measurements of high-energy cosmic rays by optimizing the configuration of an array of PMTs. [Preview Abstract] |
Friday, October 26, 2012 11:54AM - 12:06PM |
B2.00008: Investigation of thermal transmission across AlN/Si boundaries Elizabeth Carlisle, Adam Simpson, Tim Head We investigate transmission of non-equilibrium ballistic phonons generated in a Cr absorption layer across 1 micron c-axis oriented AlN films and the interface with (111) oriented Si substrates. Using phonon imaging techniques we verified good thermal conductance across the AlN/Si interface. [Preview Abstract] |
Friday, October 26, 2012 12:06PM - 12:18PM |
B2.00009: Separating Cherenkov and Scintillation Pulse Signals in High Energy Electromagnetic Calorimeters John Sandy, Christopher Cowden, Jon Clark, Nural Akchurin We propose to adapt techniques from the field of signal processing to distinguish between Cherenkov and scintillation light present in high energy electromagnetic calorimeters, such as those employed at LHC detectors. Relativistic charged particles emit Cherenkov radiation when they traverse a medium with a velocity higher than the phase velocity of light in that medium. Some materials commonly employed in high energy physics calorimetry emit scintillation light when a charged particle passes through it. Presently in calorimeters which use these scintillating materials, one cannot always separate the Cherenkov light from the scintillation light in the measured signal even though some techniques exist. Separating the two light signals from a single material requires a large divergence in the time structure or in the wavelength spectra of Cherenkov and scintillation light. This study intends to move from the time domain of the signal into the frequency domain where we split the measured signal and return to the time domain with separate estimates of the Cherenkov and scintillation light signals. [Preview Abstract] |
Friday, October 26, 2012 12:18PM - 12:30PM |
B2.00010: Overview of the Use of Graphene in Electric Double Layer Capacitors Arthur Coleman Advances in the manufacture and optimization of Electric Double Layer Capacitors or ultra-capacitors may make them a good alternative to batteries. Using graphene in the EDLC layers seems to limit the high self-discharge and voltage loss on discharge that plagues ultra-capacitors. [Preview Abstract] |
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