Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 55, Number 9
Friday–Saturday, October 15–16, 2010; Ogden, Utah
Session E1: Poster Session (16:30-18:30) |
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Room: Atrium |
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E1.00001: A Systematic Study of Techniques to Directly Measure the Saturable Absorption of Graphene Jonah Miller, Chien-Chung Lee, Thomas Schibli Recent interest in the optical properties of graphene and in the development of new saturable absorbers merits a fresh look at the balanced detection technique of characterizing a saturable absorber. Balanced detection is a technique that allows us to directly measure the nonlinear optical absorption of a material---i.e., the absorption in terms of incident intensity on that material. This allows for feedback on the quality of a material as a saturable absorber and allows methods of production to be optimized for ideal optical qualities. Because the total absorption of many materials, most notably graphene, is small, nonlinear absorption is very difficult to detect---a change on the order of 10$^{-3}$ of the total transmitted/reflected light over a dynamic range of three to four orders of magnitude. We constructed a balanced detection system and performed an analysis on the sources of error in the system and how to avoid them. Major sources of error were thermal dependence from neutral density filters and silver-coated mirrors, polarization dependence from optical components that rely on Fresnel effects, and nonlinear effects in photodiodes and electronics. [Preview Abstract] |
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E1.00002: Laser Cooling of Silicon Jeffrey Lyons, Heith Kippenhan As the world moves toward faster processors and computers, the need for more sophisticated technology grows. Quantum computers show great potential for reducing computing time and increasing internet security. The main complexity in building a quantum computer arises in finding a reliable technique for producing the qubits that are the fundamental units of quantum computing. Because much of the computer manufacturing today is done using silicon, we use a silicon-based quantum computing approach. This solid-state approach is scalable to many qubits and is a unique solution for fabricating a quantum computer. The challenge is that in order to produce these qubits a single atom has to be trapped and implanted into a silicon substrate with nanometer precision. This level of deterministic deposition is not achievable with conventional ion beam techniques. To achieve this precision, the single atom source must have small spatial extent and low kinetic energy. We are using laser cooling techniques to trap a single atom, followed by resonance ionization, to achieve these low energies. Using a tunable single frequency deep ultra-violet laser, we plan to demonstrate laser cooling of silicon. This will be the first step in making a single atom cold ion source. [Preview Abstract] |
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E1.00003: Busting Up Binaries: Stellar Interactions With Galactic Supermassive Black Holes Eric Addison, Shane Larson Gravitational wave astronomy is a new observational tool that will further our understanding of the Cosmos. Virtually everything we know about the Cosmos has been learned through observations of light; gravitational waves are a fundamentally different spectrum that can be used to learn about distant astrophysical systems. Einstein's theory of General Relativity predicts the existence of gravitational waves, and it is well known that stellar-mass compact object binaries will be among the most abundant and easily detectable sources. Gravitational waves from binary systems have not yet been directly detected, however the Laser Interferometer Space Antenna (LISA) mission is expected to detect such systems with ease. Previous analytic studies of stellar mass binaries interacting with a supermassive black hole have predicted a population of stars that spiral into the black hole along nearly circular orbits by the time they enter the LISA detection band. This research explores the three body interaction of a supermassive black hole with a stellar mass binary though numerical simulations. Using direct integration of the gravitational interactions, we are Monte Carlo simulating the black hole - binary interaction to statistically characterize the end state given arbitrary initial conditions. [Preview Abstract] |
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E1.00004: Linking Type IIn Supernovae with Massive Progenitors Leah Huk, Charee Peters, Jennifer Hoffman Within the two major supernovae types, types I and II, several subcategories have arisen in recent years that mainly differ from each other in their spectral characteristics. However, it is unclear which types of massive stars give rise to each particular subcategory of supernovae. Studying the circumstellar material (CSM) surrounding IIn supernovae, the result of mass loss episodes prior to core collapse, allows us to constrain the properties of the progenitor stars. We use a three-dimensional Monte Carlo radiative transfer code called SLIP to model hydrogen-alpha emission line profiles of IIn supernovae. The code allows us to vary several parameters of the CSM including geometry, temperature, optical depth, and initial photon distribution. We present initial comparisons of our model results with observations of SN 1997eg from the Keck Telescope using chi-squared analysis to identify the best fit from a grid of 108 models. Future comparisons of additional IIn supernovae with our models will provide overall insight into common trends amongst CSM characteristics and thus properties of IIn progenitors. This research is supported by the National Science Foundation, the University of Denver, and Vanderbilt University. [Preview Abstract] |
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E1.00005: Commisioning and ``First-Light" of the Willard L. Eccles Observatory at Frisco Peak Wayne Springer, Kyle Dawson, Paul Ricketts, Nicolas Ramsrud, Upul Samarasingha The University of Utah completed construction of the Willard L. Eccles Observatory located on Frisco Peak near Milford, Utah in October 2009. The observatory site is located on a prominent peak at an altitude of approximately 9600 feet in a region with minimal light pollution. The Frisco Peak site was chosen after careful consideration of many factors including climate, light pollution and available infrastructure. The facility houses a 32" Schmidt-Cassegrain telescope manufactured by DFM Engineering of Longmont, CO. Commissioning and development of remote operation capabilities is currently being undertaken. Monitoring of the weather and seeing conditions are being performed and confirm the excellent nature of the site for astronomical observations. The observatory facilities will be used for educational and public outreach activities as well as research projects. A description of the facility and its planned use will be provided. Measurements of the ``seeing'' and night sky background from images obtained with the telescope will also be presented. [Preview Abstract] |
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E1.00006: Galactic Dust-Busting: Mapping Dust Clouds in the Central Milky Way with Star Clusters Jennifer Simmerer, Sofia Feltzing, Francesca Primas, Rebecca Johnson Astronomical observations of galaxies are complicated by the presence of interstellar dust and gas. Large clouds of gas and dust often accumulate in the centers and disks of galaxies like the Milky Way, obscuring and altering the starlight that passes through them. We present a small-scale, high spatial resolution map of the cloud complex between us and the globular star cluster NGC 5927. We infer the presence of interstellar matter by matching stellar temperatures derived from broad-band photometry of cluster stars to stellar temperatures calculated from the spectra of those same stars. Our map makes it possible to combat the obscuration effects and extend our studies to stars that are intrinsically faint. [Preview Abstract] |
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E1.00007: Method For Identifying Cosmic Ray Events In Radar Data Jon Paul Lundquist Detection of ultra-high energy cosmic rays using radar is an idea being developed in a recent addition to the Telescope Array (TA) Project at the University of Utah. A 54 MHz transmitter illuminates the skies above the TA, and we search for radar echoes in coincidence with cosmic ray airshowers detected by conventional means. The resulting data presents several interesting difficulties. The expectation is that the radar echoes will happen on time scales of tens of microseconds, and therefore the data must be recorded at very high sample rates. Data must be sifted in real time, and accurate timing information must be preserved so as to correlate with TA data. I present two methods, using Discrete Fourier Transforms and Discrete Wavelet Analysis. [Preview Abstract] |
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E1.00008: Origins of the Elements -- An Educational Web Site Upul Samarasingha, Inese I. Ivans This poster will introduce our new and unique web site to the physics community. The main objective of our site is to provide a useful reference guide on the origins of the elements for both educators and students. Although various reference sources are available to learn about nucleosynthesis, it's a challenging task to uncover appropriate study materials and references. In this single site, we present both data and recent research results in a concise and attractive manner. Using tables and charts, the material is presented in a multi-level style. The elements were originated by different nucleosynthetic processes. This site provides a basic introduction of Big Bang nucleosynthesis, stellar nucleosynthesis and explosive nucleosynthesis. For each of the elements in the periodic table, the site gives a clear visualization of their corresponding nucleosynthetic origins. Another important feature is that the users have the direct access to the tabulated results of the abundances (both theoretical and observed) of the stars and meteorites through this educational web site. [Preview Abstract] |
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E1.00009: The Calculation of H$\beta $ Color Indices for $\delta $ Scuti Variable Stars Kelsey Jorgenson, Eric Hintz, D.K. Shreeve As part of research astronomers gather and analyze information about stars' fundamental properties. One such piece of information lies in the hydrogen beta index, gathered through spectral observations. The H-$\beta $ index is commonly used to measure surface temperature of stars as well as the age of stars or clusters. As such, it is a valuable piece of information for astronomical objects. In this study we present several hundred previously unpublished or updated H- $\beta $ index values of $\delta $ Scuti variable stars. The values were calculated from a calibration using spectroscopic observations obtained at the Dominion Astrophysical Observatory of 190 $\delta $ Scuti stars north of --1\r{ } declination and brighter than 13th magnitude. [Preview Abstract] |
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E1.00010: High Resolution Stellar Spectroscopy of Globular Cluster NGC 1261 Dan Filler, Inese I. Ivans, Jennifer Simmerer We have studied three stars in the globular cluster NGC 1261. A globular cluster is just what it sounds like, a spherical cluster of millions of stars. Their spectra contain elemental absorption lines. By determining the size (EW's) of the lines, we are able to ascertain stellar characteristics: the overall chemical enrichment from which they formed, how hot, and how dense they are. We combined our EWs with model stellar atmospheres (parameterized by specific values of temperature, density, turbulence, and chemical enrichment) and radiative transfer calculations to derive elemental abundances and stellar parameters. We then employed the derived abundances to determine the accuracy of the parameters in the following way. We minimized the trend between derived abundance and excitation potential (i.e. the atomic physics) to derive the temperatures. We adjusted the value of turbulence to minimize trends due to the broadening of absorption lines. And, we refined the value of density to equate derived enrichments for multiple ionization states of a given element. The result is that we have derived the temperatures, densities, and chemical composition of 15 elements in these objects 50,000 light years away. [Preview Abstract] |
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E1.00011: Genesis of Radio Astronomy at BYU Daniel Blakley We are beginning a new program in state-of-the-art radio astronomy at BYU. Our first effort consists of a 4-meter radio antenna designed to image hydrogen spin-flip and maser lines within our galaxy where frequencies of interest include 1.4GHz -- 1.6GHz. We employ a unique spectrometer/correllator that may be used both independently as well as in conjunction with a 5-antenna array for imaging. Our correlator/spectrometer is based upon CASPER hardware/firmware, as used at leading edge radio astronomy sites at JPL, Harvard, Deep Space Network, et al. This instrument system, to be followed by others, establishes a foundation for physics and astronomy research and teaching using state-of-the-art methods. [Preview Abstract] |
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E1.00012: Study of Geoeffective ICMES and Magnetic Clouds Simranjit Kaur Highly variable conditions prevail in the geospace environment due to variations in solar activity. The geosphere is highly affected by the solar eruptions which are responsible for some large and small geomagnetic storms. I statistically study the role interplanetary coronal mass ejections (ICMEs) and magnetic clouds (MCs) play in determining the nature and strength of the geomagnetic storms and the modulation of cosmic ray intensity observed during 1996-2009. [Preview Abstract] |
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E1.00013: Detecting Cosmic Rays at the Highest Energies with the Pierre Auger Observatory David Packard Ultra-High Energy Cosmic Rays(UHECR) are the most energetic particles in the Universe. They are constantly bombarding the earth, creating ``air-showers'' in the atmosphere yielding billions of secondary particles that can reach the ground. Where these particles come from, what their composition is, and how they achieve such large energies is still an ongoing investigation. For this investigation it is important to distinguish the real UHECR events from laser shots that are used for detector calibration. In this poster I explain my research project focus on the correct selection of laser shots minimizing the rejection of real (and very valuable!) UHECR events. [Preview Abstract] |
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E1.00014: Radioisotope-Powered Hopper Design for Europan Mission Justin Dekany, Melissa Guzman, Karthikeyan Jagadevan, Jonathan McCulley, Kevin Shipley, Steven Howe NASA and ESA have prioritized an outer planet flagship mission to Jupiter and its four largest moons. The constant cycling of material from Europa's surface to the global ocean below allows the potential for organic life similar to the eco-systems surrounding geothermal vents on Earth. The Europa Hopper model utilizes a radioisotope core, in-situ materials and a subsurface ice probe in order to minimize mass and power needs. A hopping distance of 10km was chosen to maximize the surface area coverage of Europa and increasing the potential for organic sampling and geological imaging of Europa's surface. The hopper design has mid-range power and mass needs while maintaining a substantial instrumentation package in comparison to smaller, low-power competitive designs. This mission could provide vital information both on early solar system formation and the potential existence of organic life in the Jovian system. [Preview Abstract] |
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E1.00015: The \textit{Ex-Vivo} Detection of Human Breast Cancer through High-Frequency Ultrasound Scott Jensen, Timothy Doyle, Vern Hart, Jeffrey Goodrich, Leigh Neumayer, Rachel Factor \textit{Ex-vivo} studies of human mammary surgical tissues were performed at the Huntsman Cancer Institute in order to develop an ultrasonic method to detect microscopic cancer in surgical margins during breast conservation surgery. Both pitch-catch and pulse-echo measurements were acquired using a high-frequency ultrasound system operating at 50 MHz. The ultrasonic tissue signatures were categorized into three groups: Malignant tumors, fibroadenomas, and normal tissues. An analysis in the frequency domain was performed to detect frequency dependencies and unique signatures for each of these groups. Signatures were then used in a final analysis to determine future possibilities in systematic cancer detection using this approach. Results of this study and spectral comparisons are reported. [Preview Abstract] |
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E1.00016: Spectrophotometric Analysis of Bacterial Contamination in Water Sarah Spence Bacterial contamination in water is a hazard everywhere from wells in third world countries to reclaimed water on the International Space Station. Traditional lab techniques detect bacteria in approximately 48 hours, while optical techniques can detect bacteria in as little as six hours. The Beer-Lambert Law states that absorption of light is directly correlated to the concentration of a solute in a solution. By passing light through a sample of contaminated broth, the transmittance and in turn the absorption of the solution can be observed. The transmittance data alone follows the inverse of the bacterial growth curve. A sharp drop in transmittance represents the exponential growth phase of bacteria. This drop is observed between six and eight hours following the inoculation of the laboratory samples with Escherichia coli, using both a standard lab monochrometer as well as a device designed for this study. The Optical Bacteria Detection (OBD) was designed to be effective and inexpensive, with a limited use of consumables and minimum waste generation. The OBD device uses a phototransistor as a sensor and an LED with wavelength of approximately 500 nm. Data from the monochrometer shows the sudden decrease in transmittance is most pronounced at this wavelength. The OBD can be tuned to test for other bacteria, such as Salmonella and Vibrio fisheri by changing the wavelength of the LED light source. [Preview Abstract] |
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E1.00017: Microscopy and Chemical Inversing Techniques to Determine the Photonic Crystal Structure of Iridescent Beetle Scales in the Cerambycidae Family Lauren Richey, John Gardner, Michael Standing, Matthew Jorgensen, Michael Bartl Photonic crystals (PCs) are periodic structures that manipulate electromagnetic waves by defining allowed and forbidden frequency bands known as photonic band gaps. Despite production of PC structures operating at infrared wavelengths, visible counterparts are difficult to fabricate because periodicities must satisfy the diffraction criteria. As part of an ongoing search for naturally occurring PCs [1], a three-dimensional array of nanoscopic spheres in the iridescent scales of the Cerambycidae insects \textit{A. elegans} and \textit{G. celestis} has been found. Such arrays are similar to opal gemstones and self-assembled colloidal spheres which can be chemically inverted to create a lattice-like PC. Through a chemical replication process [2], scanning electron microscopy analysis, sequential focused ion beam slicing and three-dimensional modeling, we analyzed the structural arrangement of the nanoscopic spheres. The study of naturally occurring structures and their inversing techniques into PCs allows for diversity in optical PC fabrication. [1] J.W. Galusha et al., \textit{Phys. Rev. E }77 (2008) 050904. [2] J.W. Galusha et al., J. Mater. Chem. 20 (2010) 1277. [Preview Abstract] |
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E1.00018: Solid-State Nanopore Recognition and Measurement using Shannon Entropy Tyler Wojcik, Diego Krapf Solid state nanopores are structures defined in silicon based membranes that can be fabricated using the electron beam of a transmission electron microscope. These structures can be used to electrically detect individual DNA molecules and they may potentially be used for rapid genomic sequencing. Current nanofabrication methods are manual and time-consuming and thus they do not allow for the fabrication of large scale nanopore arrays. One of the requirements in the development of an automated fabrication process is the electron microscope image processing to recognize and measure nanopore dimension in real time. Unfortunately image segmentation using pixel intensities does not yield good results due to the similar intensities inside and outside nanopore structures. Here we present a method for nanopore edge detection that uses Shannon entropy to overcome these difficulties. Texture-defined edges are determined by first calculating the Shannon entropy using a two-dimensional kernel. The image is then contrast-enhanced and a single Gaussian filter is applied to eliminate edge noise and produce a more pronounced feature. At last we segment the image and the texture-defined original edges are determined. The dimensions of nanopores as small as 2 nm are then directly measured. [Preview Abstract] |
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E1.00019: ECG Preferred Segment Enhancement using Correlation Methods Daniel Blakley Clinical quality electrocardiograms are comprised using up to 12 differential leads, placed at predefined locations on the human body. From these, a clinician chooses the best lead set to view preferred segments of the cardiac waveforms from the possible options. A new approach is proposed for better clarity using correlation methods from computed orthogonal lead sets to enable a virtual orthogonal lead set and its transformation to a preferred waveform which maximizes the preferred segment amplitude using its virtual leads. [Preview Abstract] |
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E1.00020: Non-Invasive Glucose Measurement Daniel Blakley There are two little words, when taken together have great implications: ``What IF'' In the US alone, there are millions who are burdened with diabetes and who must maintain their glucose levels by taking blood samples and having it analyzed. Even though this procedure has improved over time, still it is very intrusive and is a burden to many that must live with it. What if it were not necessary? Although it is current practice to measure glucose levels invasively (using blood samples), it may be possible to measure glucose non-invasively. Although several companies around the world have invested millions of dollars to address this problem, none have been successful thus far. However, there are many methods that hold a potential and many approaches that have not yet been explored. We are working on a review of what has been approached thus far and are entertaining proposals for a combined interdisciplinary approach which combines expertise from bioengineering, physics, and biology. We hope to learn from the unsuccessful attempts of others whilst employing innovative new approaches to this problem. [Preview Abstract] |
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E1.00021: \textit{Ab Initio} Molecular Metadynamics Study of the Base-Catalyzed Hydrolysis of N-Methylacetamide Sufian Alnemrat, Igor Vasiliev, Haobin Wang We apply the first principles metadynamics simulation technique implemented in the Car-Parrinello molecular dynamics package to study the base-catalyzed hydrolysis of N-methylacetamide in aqueous solution. Our calculations are carried out in the framework of density functional theory combined with the hybrid BLYP exchange-correlation functional The free energy surfaces and hydrolysis reaction pathways for N-methylacetamide are examined in the presence of a hydroxide ion, and 4, 16, 32, and 64 water molecules. We find that at least 32 water molecules must be explicitly included in metadynamics simulations to accurately describe the mechanism of the hydrolysis reaction of N-Methylacetamide Our theoretical estimate for the dissociation energy of N-Methylacetamide is in good agreement with the results of previous experimental and theoretical studies. [Preview Abstract] |
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E1.00022: Upper Atmospheric Particulate Monitoring and Sample Return Alan Liddell, John E. Sohl H.A.R.B.O.R. (High Altitude Reconnaissance Balloon for Outreach and Research) is a student-run program in which high-altitude balloon systems are designed, constructed, and flown by students conducting individual or group research projects. One area of interest is in the sampling of particles in the upper atmosphere. Collecting airborne particulates and studying them under an SEM can answer questions on the origins of airborne particulate matter. We could find explanations for climate change or directly measure pollution caused by smokestacks. The SEM has the capacity to capture images of particulates and determine their composition. I am building a system capable of sampling air up to 30km (100,000 ft). The system will contain a servo-controlled filter system for sampling air captured by the ascent of the balloon. Currently, filter types are being evaluated for capture rate and air flow resistance. A circuit has been built to test the mass throughput of the airflow as the balloon travels its course. A vacuum chamber is being built to simulate the nearspace environment. Testing and simulation should be complete in time to fly a finalized sample return mission in spring 2011. [Preview Abstract] |
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E1.00023: Investigations into High Altitude Particulate Monitoring Charla Boom, Spencer Hatch The High Altitude Reconnaissance Balloon for Outreach and Research (HARBOR) is a high-altitude ballooning system that takes scientific data from ground level to heights around 100,000 feet. During the 2010 summer flight season, WSU's HARBOR team launched multiple flights from Duchesne, UT. Particle diameter measurements were taken of the troposphere and lower stratosphere using a MetOne GT-526 particle counter. Tests during the pre-flight season were conducted in low-temperature and low-pressure environments to ensure functionality and accuracy of the particle counter in conditions typical of the lower stratosphere. Data from previous flight seasons suggest formation of particle layers due to wildfires. Atmospheric data collected during the 2010 flight season on August [day], 2010 showed evidence of dust layers around 30,000 feet elevation on flight HAR100819. Investigation is under way to corroborate tentative conclusions from past flights. Post-flight tests were conducted on the performance of the particle counter to determine the effects of stratospheric conditions and impact. [Preview Abstract] |
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E1.00024: Object Oriented Approach to the Algebraic Theory of Molecules Tim Wendler, Jean-Francois Van Huele Lie algebra is used to generate the quantum states of a molecule. A molecular Hamiltonian class is constructed by u(2) algebra class instances. Then a general total molecular state class is built with the Hamiltonian instances. Methods are used in the construction of normal and local modes of a given molecule with direct products of single algebra instances. Other methods are then used to raise and lower the stretching, rotational and bending quantum states of molecular instances. A clear example is then calculated for a tetrahedral molecule from the ground state gaining quanta in different forms. [Preview Abstract] |
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E1.00025: Use of Cameras in High Altitude Ballooning as a Data Integration Tool Sharon Gatrell, Murielle Parkinson, John Armstrong Integrating data from multiple sensor systems can be a challenge, especially in high altitude ballooning, where violent motion, high humidity and low temperatures can cause system failures. Camera intervalometers can be used to correlate and corroborate data from multiple systems, and relate data on board to real time. Cameras are good candidates because they are more compact than other sensor arrays, can be insulated without interfering with their operation, and can be used to independently verify multiple sensor reading simultaneously (atmosphere quality, altitude, acceleration, orientation, etc.) while providing a record of elapsed time. Inexpensive, off-the-shelf cameras can be easily modified to work unattended in hostile environments. We will present information on changing the camera's metafile (data header) to include 3-D location and other details not normally included. We will also show image correlation with other sensors such as aerosols, real time clocks and motion. [Preview Abstract] |
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E1.00026: Quantum Many-Body Tunneling of Solitons in Bose-Einstein Condensates Joseph Glick, Lincoln Carr The macroscopic quantum tunneling of ultracold bosons is studied in one-dimensional optical lattice systems. A bright soliton confined by a potential barrier is allowed to tunnel out of confinement by reducing the barrier width or by tuning the strength of the attractive two-particle interactions. We predict the escape time for the soliton, that is, when the norm remaining behind the barrier drops to 1/e. Time-Evolving Block Decimation (TEBD), a time-adaptive matrix product state method, is used to accurately model the many-body physics. Using mean-field calculations as a comparison, we independently check our results near the weakly interacting limit. We examine how the interaction strength, the number of particles, the system size, and the barrier area affect the soliton escape time. Our findings show the regimes in which the mean-field theory is widely inadequate, and the appreciable differences between a mean-field and a full quantum many-body approach. We then use TEBD to model the dynamics far beyond the mean-field limit. We calculate the entropy of entanglement between the soliton body behind the barrier and the escaped soliton tail past the barrier over time. Using two-particle correlation functions we also examine how particles in different regions of the many-body system (behind, under, or past the barrier) are entangled to one another. [Preview Abstract] |
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E1.00027: Femtosecond pump-probe reflectivity study of InGaAs/GaAs quantum dots carrier dynamics K.N. Chauhan, D.M. Riffe Ultrafast carrier dynamics have been studied on a single layer of self-assembled In$_{0.4}$Ga$_{0.6}$As/GaAs quantum dots (QDs) using femtosecond degenerate pump-probe differential reflectivity. The measurements were done with an 800 nm, 28 fs Ti-sapphire oscillator. The growth process of QDs consists of two steps, low temperature growth and high temperature annealing. Specifically, the InGaAs QD structures are fabricated on n-type GaAs(001) using molecular beam epitaxy (MBE). The In$_{0.4}$Ga$_{0.6}$As layer is deposited at 390-400 $^{\circ}$C followed by QDs self assembly at 450-540 $^{\circ}$C. Finally, these QDs are caped with a 10 nm or 100 nm layer of GaAs. Measured width and height of these QDs are typically 33 nm and 6 nm respectively. Dots annealed at higher temperature have larger base area (width and length) and reduced height as compared to those annealed at lower temperature. We have developed a rate equation model to describe the carrier dynamics and fit the reflectivity data. Dynamics depends on the size of the quantum dots: larger QDs have faster dynamics as compared to smaller dots. Additionally, dynamics are slower at higher excitation levels. [Preview Abstract] |
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E1.00028: Scanning Field Emission Microscopy Samuel Tobler, Peter Bennett We describe a ``new'' scanning probe method that is useful for imaging rough or insulating surfaces in vacuum. A conventional STM is operated in feedback mode with high bias voltage (up to 100V) and field-emission current (few nA). The large tip-sample distance (up to 50nm) makes imaging more robust than for tunneling, while retaining good lateral and vertical resolution (a few nm). This is demonstrated with images of atomic steps on Si(111) under a native oxide film. A simple electrostatic model for the imaging is presented. [Preview Abstract] |
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E1.00029: Vertical Photovoltaics Amy Balls, Cary Tippets We are exploring low cost approaches for fabricating three dimensional nanoscale structures. These vertical structures could significantly improve the efficiency of devices made from low cost photovoltaic materials. The nanoscale vertical structure provides a way to increase optical absorption in thin photovoltaic films without increasing the electronic carrier separation distance. The structure is a high temperature transparent template with a dense array of holes on a 400 -600 nm pitch fabricated by a combination of e-beam lithography and nanoembossing. First a master was fabricated using e-beam lithography and the pattern was transferred into PDMS. The contacts and p-i-n layers were then deposited onto the structure and the optical properties were tested. [Preview Abstract] |
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E1.00030: Temperature and Endurance Time of Electrostatic Field Strengths of Polymeric Spacecraft Insulators Charles Sim, Alec Sim, J.R. Dennison The electrostatic breakdown of polymeric materials is important in the design and lifetimes of power line, spacecraft, computational systems, and electronic military components. The key parameters in determining material lifetime include the applied temperature and electric field and the material parameters (Gibbs free energy and density of states). This study measures the endurance time to breakdown under an applied static electric field for low density polyethylene (LDPE) as a function of field strength and temperature. Using a custom high vacuum chamber, well characterized ramping procedures and temperature control, the time to breakdown is accurately determined for endurance times ranging from 10$^{0}$ s to 10$^{5}$ s. The measured endurance time data for LDPE has been fit with a new theoretical formalism that describes a transition between two established theories based on recoverable and irrecoverable defect formation. [Preview Abstract] |
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E1.00031: Exchange bias in [Co/Pd]/IrMn multilayers Young Byun, Karine Chesnel, Matt Carey, Eric Fullerton Exchange bias occurs when a Ferromagnetic (F) layer is placed at the vicinity of an antiferromagnetic (AF) layer. The bias effect is induced in the F layer by uncompensated spins at the interface with the AF layer, and results in a shift in the magnetization loop. We study here [Co/Pd]IrMn multilayers with perpendicular magnetization, where Co/Pd is F, and IrMn is AF. I will present magnetometry results obtained by Vibrating Sample Magnetometry (VSM) and Extraordinary Hall Effect (EHE). While EHE can be used at room temperature, VSM allows varying the temperature down 5K under up to 9T. I will show magnetization loops measured on [Co/Pd]IrMn multilayers at different temperatures from 20K up to 400K after Field cooling and after Zero Field Cooling. The magnetization loops are used to quantify the saturation field, coercive and nucleation points, and possible bias field at each temperature and cooling condition. We observe a bias when the sample is cooled in the presence of a field. We have studied the amount of bias as function of temperature and of the magnitude of the field applied during the cooling process. [Preview Abstract] |
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E1.00032: Electron Induced Luminescence of Insulating Polymeric Materials Doug Ball, J.R. Dennison The study of luminescence and electron transport in disordered insulating materials provides detailed information about the material structure and interaction of incident electrons within a material. Electron induced luminescence of insulating polymeric materials has been observed in tests by the USU Materials Physics group. Conduction electrons can transition between extended states in the valence and conduction band and a distribution of localized trapped states within the band gap. Electron transport and luminescence is governed by the distribution of states and transition rates between them. This study investigates the exponentially decaying signatures of both luminescence and sample current under electron bombardment and relates their origins and relative intensities to proposed theories based on quantum band structure models. [Preview Abstract] |
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E1.00033: Effects of Surface Treatment and Anneal Temperature on Poly(3-hexylthiophene) Infiltration in Zinc Oxide Nanorod Arrays Taylor Wood, Darick Baker, Dana Olson, Reuben Collins, Thomas Furtak The performance of a hybrid inorganic/organic photovoltaic cell is crucially dependent on the contact between the inorganic electron acceptor and the organic electron donor. In this study, we seek to optimize the infiltration and local polymer ordering of poly(3-hexylthiophene) (P3HT) into ZnO nanorod arrays through thermal annealing and chemical surface treatment. ZnO nanorods were grown on glass substrates and subsequently spin-coated with P3HT. Some of the nanorod arrays were chemically treated with ocadecyltriethoxysilane (OTES), phenyltriethoxysilane (PTES), and octadecanethiol (ODT) to form organic molecular layers on the rod surfaces. Samples were then thermally annealed at 150 and 220 \r{ }C and characterized using UV-Vis spectrophotometry and electron microscopy. Our results revealed that while high-temperature annealing increases the amount of P3HT infiltration, it also destroys local polymer ordering and thus charge carrier mobility. Results from chemically-treated samples were largely inconclusive and merit further research. This material is based upon work supported by the National Science Foundation through Grant Nos. DMR-0820518 and DMR-0907409. [Preview Abstract] |
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E1.00034: The Effects of Surface Modification on Spacecraft Charging Parameters Amberly Evans, J.R. Dennison Charging of materials by incident radiation is affected by both environmental and physical conditions. Modifying a material's physical surface will change its reflection, transmission and absorption of the incident radiation which are integrally related to the accumulation of charge and energy deposition in the material. An optical analysis of the effect of surface modification on spacecraft charging parameters on prototypical Cu samples is presented. Samples were roughened with abrasive compounds ranging from 0.5 to 10 microns in size. Using a UV/VIS/NIR light source and a diffraction grating spectrometer, measurements were performed on pristine and modified materials. The index of refraction and absorption coefficient were determined using the Fresnel Equations. The resulting absorption coefficient and Tauc plot were used to determine the energy of the band gap. The measured spectra confirmed that surface modification does induce changes in optical reflection, transmission, and absorption. The increased absorption observed results in increased photon energy deposited in the material, leading to increased charge emission through the photoelectric effect. [Preview Abstract] |
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E1.00035: The Effect of Long Term Space Environment Exposure on Optical Properties of Spacecraft Materials Danielle Fullmer, Amberly Evans, J.R. Dennison, Joshua L. Hodges The Utah State University Material Physics Group took part in the State of Utah Space Environment {\&} Contamination Study by flying samples on the International Space Station aboard the Materials International Space Station Experiment 6 payload. Pre-flight and post-flight analysis include density measurements to determine mass loss, optical microscopy, diffuse and specular reflectivity/absorptivity/transmissivity, and thermal emissivty/absorptivity. Post-flight measurements also include FTIR, SEM and STM. A primary objective of this project was to study the effects of prolonged exposure to the low earth space environment on the optical and thermal properties of the materials. Exposing these potential spacecraft materials allows us to characterize their performance in the space environment. The optical photographs show the physical damage inflicted on the materials by space. The reflection, absorption, and transmission measurements give insight to how the material interacts with the intense light of space and how it will accumulate charge, thus contributing to spacecraft charging. Emissivity determines equilibrium temperature in space. [Preview Abstract] |
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E1.00036: Measuring and Controlling Spatial Fluctuations in Organic Photovoltaic Devices Alex Dixon, Sean Shaheen, Jan-Carlos Kuhlmann, J.C. Hummelen The power conversion efficiency of organic photovoltaic (OPV) devices is controlled by processes and structures at many length scales. The nanoscale morphology of a blend of electron-donating and electron-accepting molecules plays a critical role in determining exciton dissociation and charge transport properties. On a larger length scale of tens of nanometers to several microns, there can exist spatial fluctuations in the photocurrent of the devices that act to degrade the overall diode properties and efficiency. In this work, we investigated fluctuations in photoconductivity of the poly(phenylene vinylene) derivative MDMO-PPV blended with a fluorene-derivatized fullerene, FCBM, with alkyl side-chains of various lengths. Measurements of the local photocurrent in the polymer-fullerene blends performed with conductive tip Atomic Force Microscopy showed fluctuations on the scale of $\sim $100 nm. In all cases the fluctuations were large enough (10{\%}-30{\%}) to likely cause decreased macroscopic performance in OPV devices, but the size and structure of the fluctuations depended on the length of the alkyl tail on the fluorene group, with the shortest tail giving the largest lateral features and the smoothest films. Here we present analysis of the topology of the fluctuations and the role of molecular structure and material processing conditions leading to their formation. [Preview Abstract] |
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E1.00037: Systematic Neutron Scattering Investigation of Structural Evolution in Pyrochlores at Low and High Temperatures Adrian Losko, Sven Vogel, Maulik Patel, James Ryne Pyrochlore structures R$_{2}$Ti$_{2}$O$_{7}$ (with R being a rare earth element) belong to the Fd-3m space group and the family of rare earth titanates. Recently, pyrochlores have attracted great attention as nuclear waste form and possible high temperature solid oxide fuel cell (SOFC) materials. Furthermore, Dy$_{2}$Ti$_{2}$O$_{7}$ was reported by several authors to be the first structure in which magnetic monopoles were observed. This latter observation is related to the existence of spin ice in these structures, a phenomenon referring to a geometrical frustrated magnetic system, whereby ``frustration'' describes the effects that occur when interactions of similar strength compete and prevent a system from settling into a unique ground state. In spin ices, like Dy$_{2}$Ti$_{2}$O$_{7}$, only the rare-earth atoms have a magnetic moment and these cations reside in a network of corner sharing tetrahedra forming the pyrochlore lattice. Here we present structural parameters such as cation ordering, bond lengths and bond angles to quantify the geometrical frustration and characterize the crystal structure over a temperature range from $\sim $5K to 1300K. [Preview Abstract] |
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E1.00038: Investigating short-period gravity wave characteristics over Rothera, Antartica (68$^{\circ}$S) Thomas Martin, Jon Pugmire, Mike Taylor, M.J. Jarvis, Kim Nielsen, Dominique Pautet As part of a collaborative program between British Antarctic Survey and Utah State University, we present an intra-annual study of short-period, mesospheric gravity wave events observed over Antarctica in the near infrared OH emission. The measurements were made using an all-sky airglow imager operated at Rothera Station (68$^{\circ}$S, 68$^{\circ}$W), situated on the Antarctic Peninsular. A total of 5 austral winter seasons have been analyzed (2002-2009). Distributions of their observed wave parameters were found to be similar to previous findings using imaging instrumentation at other latitudes in the Northern and Southern Hemispheres. However, the observed wave headings exhibited strong anisotropy that was also found to be remarkably consistent from year to year, establishing a predominance for westward wave propagation over the Antarctic peninsula. In this poster we present data from each year summarizing the seasonal wave properties focusing on wave anisotropy and the strong year to year consistency. [Preview Abstract] |
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E1.00039: Quantifying entanglement in composite systems by Stern-Gerlach--like interactions Suzanne Flaten, Jean-Francois Van Huele Entropy is an accepted measure to quantify entanglement for bi- partite systems in pure states. We review the formulation of pure and mixed composite states and study the challenge of quantifying entanglement for multipartite systems states. Traditional Stern-Gerlach (SG) devices, evolve a non-entangled product state of spin and space into a maximally-entangled superposition. I will consider combinations of SG-like devices to quantify entanglement for the composite system, as a function of the incompatibility of the individual devices on the subsystems. [Preview Abstract] |
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E1.00040: Probing Atmospheric Dynamics with High Altitude Balloons Linsey Johnson, Shane L. Larson HARBOR is a high altitude balloon capable of carrying scientific experiments to altitudes of 100,000 feet or more, providing access to the troposphere, tropopause and lower stratosphere. We report on atmospheric profiling using a high resolution data logger capable of recording temperature and pressure at regular intervals during a HARBOR flight. This data is used for understanding dynamic variability of the lower atmosphere and is required for interpreting essential secondary data from other experiments on a given flight (such as HiSAM dust monitor, balloon dynamics, and flight reconstruction). [Preview Abstract] |
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E1.00041: Smarandache's Cevians Triangle Theorem in the Einstein Relativistic Velocity Model of Hyperbolic Geometry Catalin Barbu We present a proof of Smarandache's cevian triangle hyperbolic theorem in the Einstein relativistic velocity model of hyperbolic geometry. [Preview Abstract] |
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E1.00042: The First Ten Months of Investigation of Gravity Waves and Temperature Variability Over the Andes Jonathan Pugmire, Neal Criddle, Michael Taylor, Dominique Pautet, Yucheng Zhao The Andes region is an excellent natural laboratory for investigating gravity wave influences on the Upper Mesospheric and Lower Thermospheric (MLT) dynamics. The instrument suite that comprised the very successful Maui-MALT program was recently re-located to a new Andes Lidar Observatory (ALO) located at Cerro Pachon, Chile to obtain in-depth seasonal measurements of MLT dynamics over the Andes mountains. As part of the instrument set the Utah State University CEDAR Mesospheric Temperature Mapper (MTM) has operated continuously since August 2009 measuring the near infrared OH(6,2) band and the O2(0,1) Atmospheric band intensity and temperature perturbations. This poster focuses on an analysis of nightly OH temperatures and the observed variability, as well as selected gravity wave events illustrating the high wave activity and its diversity. [Preview Abstract] |
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E1.00043: Iron Nanoparticles for Environmental Applications Studied by Magnetic Force Microscopy Trevor Bowman, Colin Inglefield, Marek Matyjasik Iron nanoparticles have been widely used in environmental applications due to the ability of the iron to extract harmful chemicals from solution. Because of this trait, zero-valent, iron nanoparticles are currently being used in many water reclamation processes. Using Atomic Force Microscopy (AFM), and Magnetic Force Microscopy (MFM) with CrCo magnetic tips, we were able to obtain images of various materials with the hope to track nanoparticulate iron through different chemical reactions commonly used in water reclamation. We used standard MFM techniques in our investigation, with the magnetic information coming from a measure of the change of phase of the tip's resonant oscillation. Preliminary results of the study using commercial grade nanoparticle solutions evaporated on flat glass surfaces and plans for future experiments will be presented. [Preview Abstract] |
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E1.00044: A study of substrate factor on carbon nanotube forest growth Carlos Read, Robert Call, T.C. Shen Carbon Nanotube Forests (CNFs) are vertically grown carbon nanotubes. They can be as tall as millimeters with radii from less than one nm (single-walled) to more than a hundred nm (multi-walled). Their high surface to volume ratio provides a unique material system for EM radiation absorption, dry adhesive and biosensor applications. There have been numerous, but not all consistent reports on successful CNF growth. We find that the optimal growth conditions depend critically on the substrate, at least by the spray pyrolysis method we have adopted. To determine the substrate factor, we have investigated two grades of copper, stainless steel, silicon and quartz as substrates on which the catalytic particles and carbon source are delivered simultaneously by a ferrocine-xylene solution. We find that the interplay of lateral and in-diffusion of the iron atoms and interactions with existing gas molecules such as H2, O2, H2O on the substrates dictate the CNF growth. [Preview Abstract] |
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E1.00045: Flight Dynamics of High Altitude Research Balloons Ian Sohl Dramatic motions have been observed by instrumentation loaded in payloads attached to high altitude weather balloons. Several HARBOR flights have been completed with six-axis attitude sensors and a high definition video camera that allowed us to analyze the balloon's motion. Turbulence in the atmosphere, especially near the jet stream, results in dramatic oscillations---sometimes swinging the payload above the balloon. Other unexpected motions include rapid spinning (as in a barrel roll) of the entire package. We are correlating these motions with observed atmospheric conditions and addressing issues related to payload safety, mission tracking, and recovery. Also of interest are the dynamics of balloon rupture at low atmospheric pressure and the response of the parachute recovery system to that environment. HARBOR (High Altitude Reconnaissance Balloon for Outreach and Research) is a program in which scientific payloads are designed, constructed, and flown by students using weather balloons to reach the edge of space. These flights are similar to the hundreds of weather balloons launched twice a day by the National Oceanic and Atmospheric Administration for which very little is actually known about the flight dynamics. [Preview Abstract] |
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E1.00046: Recovery and control system for near-spacecraft Scott Rollins, John E. Sohl Weber State University's High Altitude Reconnaissance Balloon for Outreach and Research (HARBOR) is a platform for student scientific experiments in low temperature, low pressure environments at the edge of space. Future instrumentation plans for HARBOR flights will make it impossible to fly less than twelve pound payloads (this changes the flight category under FAA regulations) and these payloads will be more sensitive to impact damage. This will require larger parachutes. Under a larger parachute the HARBOR near space craft can drift for many kilometers while descending through the jet stream from the stratosphere. Thus, it has become mission critical to find a way to exercise more control over descent rate and landing zone. A parachute ejection system will allow the HARBOR team to virtually pick their landing zone, open a parachute below the jet stream or release a second chute to further slow the descent in order to protect fragile instrumentation. The system will monitor the craft's position in 3 dimensions and will have radio telemetry as a backup to the onboard processor. [Preview Abstract] |
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E1.00047: Linewidth measurement of table-top EUV laser Lukasz Urbanski, Mario Marconi, Jorge Rocca, Limin Meng, Annie Klisnick We report on linewidth measurement of a capillary discharge EUV laser. The measurement principle was based on the wavefront division interference. The wavefront of a neon-like argon, $\lambda $=46.9nm, EUV laser was split and brought to interference in a Fresnel bi-mirror interferometer setup. The optical path difference was varied in order to obtain interference fringes visibility curves. From these curves it is possible to evaluate the linewidth of the laser amplifier. No line rebroadening due to Doppler effect was observed when the laser medium length was changed. Different plasma conditions were applied by varying the discharge conditions. [Preview Abstract] |
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E1.00048: An Introduction to Biquaternion Number, Schrodinger Equation, and Fractal Graph Victor Christianto, Florentin Smarandache It is known that quaternion number has wide application in theoretical physics and engineering fields alike, in particular to describe Maxwell electrodynamics. In the meantime, recently this quaternion number has also been used to draw fractal graph. The present note is intended as an introduction to this very interesting study, i.e. to find linkage between quaternion/biquaternion number, quantum mechanical equation (Schr\"{o}dinger equation), and fractal graph. Hopefully this note will be found useful for subsequent study. [Preview Abstract] |
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E1.00049: CKM Matrix and CP Violation in B Mesons: Status and Future Outlook Zafar Yasin CP violation explains, some of the observed difference between matter and antimatter universe. The Standard Model prediction of CP violation can be represented by Cabibbo Kobayashi Maskawa (CKM) matrix. B-factories have provided the precision tests of CKM paradigm. A review, summary of the main results, and future prospects of B physics will be presented. [Preview Abstract] |
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E1.00050: Smartphones as Integrated Kinematic and Dynamic Sensors for Amusement Park Physics Applications Stephanie Peterson, J.R. Dennison USU has hosted Physics Day at Lagoon and has attracted more than 120,000 secondary educators and students over 21 years.~During this educational day, students explore basic physics concepts and apply their classroom content outdoors, in real world applications. As part of the event, USU's Physics Department provides curriculum to be used at Lagoon, in similar outside venues, and in the classroom. One such educational instrument, which is a primary focus of this work, is student workbooks filled with activities ranging from very simple to more advanced topics. Workbooks cover the properties of waves, relative velocity, and acceleration, topics which have historically challenged students and future topics include kinematics, energy, and forces. The topics were selected based on requests from teachers throughout the Intermountain Region and identified deficiencies in student performance on core curriculum assessments. An innovative approach is to identify physical application of iPhone and Android smartphone software technologies, which make use of dynamic and kinematic sensors. These technologies will allow students to realize their ability to do quantitative physics calculations anywhere, anytime; a smart device which is highly salable to today's teenage learners. This also provides an exciting approach to more fully engage students in learning physics concepts. [Preview Abstract] |
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E1.00051: Experimental Manipulation of a Non-Neutral Ion Plasma Using FT-ICR Techniques Chad Williams, Bryan Peterson The goal of our project is to experimentally determine the half life of beryllium-7. We plan to do this by singly ionizing beryllium atoms and containing them in a non-neutral plasma state as they decay. In order to correctly make this measurement, however, we need a clean plasma of high density containing solely Be-7 atoms. Due to the variable amounts of impurities in the Be-7 samples produced in our lab, it is necessary to implement the technique of Fourier Transform Ion Cyclotron Resonance (FT-ICR). By exciting the cyclotron radius of these particles trapped in a magnetic field we seek to expel these impurities from the plasma, leaving pure Be-7. Also, a technique has been developed for successfully stacking multiple pulses of plasma inside of our Malmberg-Penning trap. Recent changes in the internal structure of trap confinement rings will grant us greater efficiency in the use of these techniques. [Preview Abstract] |
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E1.00052: Novel Numerical Solution to the Plasma Kinetic Equation Joseph Spencer, Eric Held, Jeong-Young Ji One way to characterize plasmas is in terms of fluid moments such as density, flow velocity and temperature for each species. These moments can be computed simply from a single function defined over velocity space called the distribution function. Directly solving the plasma kinetic equation, which governs the time evolution of the distribution function, is a difficult task, however, even on massively parallel computers. One primary difficultly lies in developing an efficient treatment of the nonlinear Coulomb collision operator. Computer codes which use numerical methods to solve this kind of problem are called Fokker-Planck codes. In this poster, we describe preliminary development of a general Fokker-Planck code that uses a combination of finite-element(FE)/Fourier representation of velocity space. For magnetized plasmas, it is anticipated that the Fourier expansion in the gyro-angle coordinate will converge rapidly. This assumption, as well as the convergence properties of the FE representation will be discussed in relation to the simple problem of a beam of particles slowing down off a background, Maxwellian plasma. [Preview Abstract] |
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E1.00053: Parallel heat flow closure for toroidal plasmas Mukta Sharma, E.D. Held, J.Y. Ji Analytical and numerical work is done to understand controlled magnetic fusion experiments such as tokamaks, a doughnut-shaped magnetic confinement device that may form the basis of future fusion reactors. In such systems plasma can be described in terms of transport equations obtained from the kinetic equation. We close the density, momentum and energy conservation equations by solving the drift kinetic equation and deriving parallel heat fow closure. A Chapman-Enskog-like approach is adopted where the distribution function is written as the sum of a dynamic Maxwellian and a kinetic distortion, $F$,expanded in Legendre polynomials $P_l (v_\| /v)$. To lowest order, the magnetic moment and total energy of the particles are conserved. In contrast to previous derivations, this work does not bounceaverage when solving the lowest-order drift kinetic equation. In contrast, a Fast Fourier Transform algorithm is used to treat the one-dimensional spatial domain along the magnetic field. This approach allows for parallel acceleration as well as examination of the closures in all collisionality regimes. [Preview Abstract] |
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E1.00054: Symmetry Imprints and Singularity Structure in Nonlinear Dynamics Kelley Commeford We have analytically explored the effect of a discretely symmetric impulse on a vortex of definite winding number. The impulse imprints singularities on the vortex, which propagate outward in a peculiar pattern. An analytical description of this phenomenon was previously found for the constant potential. Here, we extend those results to the case of a harmonic potential using a Feynman propagator. We show that the vortex breaks into singularities, which then oscillate around the vertical axis. This analysis is valid for Bose-Einstein condensates in harmonic traps as well as pulses in GRIN mediums in fiber optics. [Preview Abstract] |
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E1.00055: The Farey series devil's staircase: Connection to dynamical-systems, statistical physics, music theory and music perception? Richard Krantz, Jack Douthett, Julyan Cartwright, Diego Gonzalez, Oreste Piro Some time ago two apparently dissimilar presentations were given at the 2007 Helmholtz Workshop in Berlin. One by J. Douthett and R. Krantz focused on the commonality between the mathematical descriptions of musical scales and the long-ranged, one-dimensional, anti-ferromagnetic Ising model of statistical physics. The other by J. Cartwright, D. Gonzalez, and O. Piro articulated a nonlinear dynamical model of pitch perception. Both approaches lead to a Farey series devil's staircase structure. In the first case, the ground state magnetic phase diagram of the Ising model is a Farey series devil's staircase. In the second case, the ear is modeled as a nonlinear system leading to a three-frequency resonant pitch perception model of the auditory system that exhibits a devil's staircase phase-locked structure. In this poster we present a summary of each of these works side-by-side to illuminate the link between these two seemingly disparate systems. Adapted from JMM Vol. 4, No. 1, 57, Mar. 2010. [Preview Abstract] |
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