Bulletin of the American Physical Society
Joint Fall 2010 Meeting of the Texas Sections of the APS, AAPT, Zone 13 of SPS and the National Society of Hispanic Physicists
Volume 55, Number 11
Thursday–Saturday, October 21–23, 2010; San Antonio, Texas
Session FP1: Poster Session (5:00-7:00PM) |
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Room: University Center III Ballroom II, 1st floor |
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FP1.00001: Estimating Ultraviolet Solar Irradiance from Total Solar Irradiance: A Nine City Comparison Eugene Clark This paper presents new empirical equations that estimate hourly solar ultraviolet irradiance from the measured total solar irradiance and the solar zenith angle. These equations are based on data taken in 4 US cities (San Antonio, TX, Atlanta, GA, Albany, NY and Fairbanks, AK). Data taken in all 4 of these US cities utilized Eppley model PSP and TUVR radiometers. The response of the TUVR is dominated by UVA, but also includes some of the UVB region of the spectrum. The empirical equations based on the US data are compared with previously published equations based on data measured in 4 cities in Spain and one city in northern China. In all nine cities, the UV fraction of the total solar irradiance increases from about 4{\%} under cloud free conditions to about 8{\%} under heavily overcast conditions. [Preview Abstract] |
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FP1.00002: Generalized Quaternion Quantum Electrodynamics from Ginzburg-Landau-Schrodinger type Equation V. Christianto, Florentin Smarandache Despite incomparable achievement of Quantum Electrodynamics and its subsequent theories, there are some known limitations and unsolved theoretical problems until this time, including ``renormalization'' condition and its generalization to larger systems. While renormalization problem has been declared as ``settled,'' yet it is known for their own founding fathers (Feynman {\&} Dirac, for instance) this question remains unsolved satisfactorily. Other known problems include limitation to explain anti-hydrogen phenomena, and confinement problem in quantum chromodynamics theory. [Preview Abstract] |
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FP1.00003: Quantum diffusion in optical lattices Taylor Bailey, Carlos Bertulani, Eddy Timmermans We study quantum diffusion in optical lattices. After an initial transient, atoms diffuse thought the lattice with a non-linear dependence on the lattice parameters. We demonstrate these results through numerical work on one-dimensional and three-dimensional solution of the time-dependent wave equation. We provide an analytical insight of the diffusion time on the lattice parameters. Furthermore, we present a applications to experimental results. [Preview Abstract] |
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FP1.00004: Modeling Laser-Tissue Interactions: Implementing Thermal Models and the Wave Equation to Simulate Photon Transport in Tissues Frederick Barrera, Dhiraj Sardar The tracking of photons through turbid media (e.g. tissues) has been studied extensively from an experimental vantage point. In addition, myriad computational techniques have also been developed to simulate the interaction of light with tissues. These tissues are difficult to characterize- since their components are exceedingly variegated- and thus present many challenges to clinicians who require models which precisely predict the location and time evolution of energy deposition. Furthermore, the interaction of the turbid media sample with the source of radiation typically involves many dynamic mechanisms (e.g. mechanical, photochemical etc.) Indeed, under certain dynamic conditions, optical properties (e.g. index of refraction, absorption coefficient etc.) are not constant. Using models of thermal distribution, and accounting for an incident source of electromagnetic radiation an analysis may be performed. The differential equations describing these processes may be solved numerically using a finite element technique. [Preview Abstract] |
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FP1.00005: Photophysical Study of Novel Perylene Analogues for Biophysical Applications Jorge Palos-Chavez, Mark Penick, Rolando Valdez, George Negrete, Lorenzo Brancaleon Perylene and perylene derivatives have been shown to be useful in a variety of photoinitiated applications, such as molecular dyes, organic solar cells, etc. Recently we started the characterization of novel 3,9-perylene analogues which could potentially lead to the synthesis of novel molecules with improved ability to separate charges. We have characterized the basic photophysical properties of these molecules, and we are currently investigating the photochemistry that leads to photoproducts in chlorinated compounds. Spectroscopic measurements show the substantial changes in photophysical parameters consistent with the conversion of the original compounds into photoproducts. SEM and AFM imaging show that these photoproducts form ordered particles. Mass spectrometry studies have confirmed the presence of these photoproducts as well. [Preview Abstract] |
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FP1.00006: Characterization of Rare Earth Oxide/Gold Composites Synthesized by Control of Surface Composition Zannatul Yasmin, Robert Dennis, Dhiraj Sardar, Maogen Zhang, Waldemar Gorski, Kelly Nash The need for novel nanosized biosensors has resulted in increase interest in nanocomposites. The challenge in development of materials is that they should offer robust and tunable characteristics (fluorescence, magnetic, thermal behaviors, etc.) while remaining biocompatible. In this study, we use small molecules to attach transition metal nanostructures (gold spheres) to select rare earth oxide (Er$^{3+}$:Y$_{2}$O$_{3})$ particles synthesized by a urea precipitation method. The goal is to enhance the fluorescence of the rare earth materials through surface plasmons resonance generated by the gold structure while achieving dispersibility of the particles. The attachment of gold nanoparticles (Au NPs, $\sim $20 nm) to the surface of rare earth nanoparticles (RENPs, $\sim $100 nm) is achieved by the surface modification with (3-Mercaptopropyl) trimethoxy-silane (MPTS); the average numbers of Au NPs per RENP is controlled by the composition of MPTS and Propyltrimethoxysilane (PTMS, without functional groups). Characterization of the physical properties is performed by Fourier transform infrared spectroscopy and scanning electron microscopy. Fluorescence spectroscopy is used to compare the radiative decay rates of nanocomposites to unmodified particles. The resulting structures will be used in studies of bulk and particle polymer composites for potential biosensing and drug delivery applications. [Preview Abstract] |
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FP1.00007: Ultra fast response of arrayed waveguide gratings: a phenomenological quantum approach Daniel Dominguez, John Sandy, Luis Grave de Peralta Using~a phenomenological~quantum description of the ultra fast response of arrayed waveguide gratings (AWG) illuminated with relatively intense short pulses of light, we show that integrated-optics pulse shapers based on AWGs can be used to produce interference between femtosecond pulses of light in conditions where the which-path information is available. We discuss the implications of this result for the Heisenberg uncertainty principle. [Preview Abstract] |
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FP1.00008: Optical losses and wave-front distortions in the reflection of light from a photonic-crystal mirror Travis Miller, Sergio Cantu, Volker Quetschke, Malik Rakhmanov, Yi-Chen Shuai, Deyin Zhao, Weidong Zhou The photonic crystal mirror, based on patterned silicon nanomembrane technology, promises many applications because of its very high reflectivity at 1550 nm wavelength. We determine the reflectivity and optical losses of a such a mirror using resonant Fabry-P\'{e}rot cavity and measuring its line width. We also investigate the wavefront distortions caused by the photonic crystal pattern on the mirror with a Michelson interferometer by interfering the beam reflected from the mirror with a reference beam with an ideal wavefront. In both experiments we incorporate rotational degree of freedom to determine polarization dependence of these phenomena. [Preview Abstract] |
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FP1.00009: Experimental Investigation of the Possibility for Negative Refraction in Si Opals Liliana Ruiz-Diaz, Malik Rakhmanov, Volker Quetschke, Anvar Zakhidov Synthetic opals are photonic crystals made of silica nano-spheres arranged in a FCC crystalline structure. Such opals are believed to possess negative refraction for certain wavelength of light. We propagate two laser beams (405 nm and 705 nm) through opal prisms and measure their angles of refraction. We also use a broadband light source to select several frequencies in the visible range with a diffraction grating. In addition, we study the photonic band gaps in this material. For certain directions of the incident light the opal samples exhibit total reflection due to the existence of the photonic band gap. [Preview Abstract] |
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FP1.00010: Analyses of the Ultraviolet Spectra of Er$^{3+}$ in Er$_{2}$O$_{3}$ and Er$^{3+}$ in Y$_{2}$O$_{3}$ Sreerenjini Chandra, John B. Gruber, Gary W. Burdick, Dhiraj K. Sardar The ultraviolet (uv) absorption spectra of trivalent erbium (Er$^{3+})$, representing transitions to all energy levels below 44500 cm$^{-1}$, have been analyzed for the crystal-field splitting of the multiplet manifolds of Er$^{3+}$(4$f^{11})$ in C$_{2}$ symmetry cation sites in single-crystal Er$_{2}$O$_{3}$ and Er$^{3+}$:Y$_{2}$O$_{3}$. A solid solution exists between the two compounds without altering the local symmetry, which allows us to identify the weaker transitions in Er$^{3+}$:Y$_{2}$O$_{3}$ from the stronger transitions observed in the uv spectrum of Er$_{2}$O$_{3}$. A total of 134 Stark levels representing 30 multiplets have been modeled using a parametrized Hamiltonian defined to operate within the Er$^{3+}$(4$f^{11})$ configuration. The crystal-field parameters were determined through use of a Monte Carlo method in which 14 independent crystal-field parameters were given random starting values and optimized using standard least-squares fitting between calculated and experimental levels. The consistent agreement between the experimental and calculated Stark levels in both crystals can be very useful for the ongoing research in intensity analyses and magneto-optical studies on these crystals. [Preview Abstract] |
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FP1.00011: Mapping the double-slit diffraction pattern Richard Selvaggi, Charles Rogers, Clay Richardson A red laser, movable double-slit, movable micrometer mounted single-slit light block, and CCD were utilized to map out the single and double-slit diffraction patterns between 0 and 30 millimeters. The three dimensional mapping results demonstrate that the double-slit troughs similarly redirect the electromagnetic energy and light particles. The measured alternating path of the electromagnetic energy and light particles in the double-slit diffraction pattern is different than the theoretic path of light waves defined by destructive interference and indicates that theoretical light waves do not always have electromagnetic energy. George Monk's 1937 and Richard Feynman's 1964 finding of conservation of electromagnetic energy in the double-slit light experiment present the following questions: 1) What are the mass-less and energy-less destructive interference light waves found in the double-slit troughs? 2) What force is applied to and what energy is consumed by the work of redistributing the electromagnetic energy and light particles in the double-slit diffraction pattern? 3) Is this unknown force and unknown energy the result of dark matter found in the double-slit troughs? [Preview Abstract] |
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FP1.00012: A Chandra ACIS Observation of the Pulsar-Wind Remnant RCW 103 Estela Jordan, Eric M. Schlegel We describe spatially-resolved, CCD-resolution spectroscopy of the supernova remnant (SNR) RCW 103 as observed by the Chandra X-ray Observatory during a 19.1 ksec exposure. The outstanding spatial resolution of the Chandra ACIS images resolve diffuse filaments across the remnant, as well as what appear to be explosion fragments, or ``bullets,'' extending beyond the x-ray bright region in the southwestern part of the SNR. Observed features are soft (E $<$ 3 keV) and we detect evidence of line emissions at several energies. The x-ray bright regions in the southwestern and northeastern part of RCW 103 are consistent with enhancements of optical, infrared, and radio emissions. [Preview Abstract] |
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FP1.00013: Observations of the 2010 January Outburst of the Recurrent Nova U Scoprius using NASA's Swift Marilyn Moore, Sabrina Engelhardt, Laura Vega, Laura McMaster, Eric Schlegel, Ashley Pagnotta We report on X-ray observations of the recurrent nova U Scorpius (U Sco) obtained with NASA's Swift during the 2010 Jan outburst. X-ray spectra were obtained in the 0.1-10 keV band at least once per day throughout the outburst which commenced on 2010 Jan 28 and lasted $\sim$70 days. We fit the spectra with an absorbed, low-order continuum component; the fits yield an integrated X-ray luminosity, the interstellar absorption column, and a pseudo-temperature derived from the continuum parameter. We describe the overall evolution of the X-ray flux as well as the absorption and temperature across the burst. [Preview Abstract] |
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FP1.00014: Analytical models for the sun John Fuqua, Carlos Bertulani We investigate analytical models for the sun by fitting the parameters of the models to reproduce the numerical solutions of the hydrostatic equations governing the properties of the sun. The advantage of the analytical models is that they allows a simple description of derived properties such as the neutrino flux. [Preview Abstract] |
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FP1.00015: Numerical Methods for Modeling Cosmic Ray Propagation in the Galaxy Hugo Espejel, Edmund Bertschinger This work seeks to investigate the trajectories of cosmic ray (CR) particles traveling from a source, like a pulsar or supernova, to Earth. Galactic CRs of moderate energy travel in tightly wound helices around the Galactic magnetic field lines.~ To better understand how this propagation is affected by errors from numerical integration, a model of the trajectory of a simple harmonic oscillator (SHO) in 2-dimensional phase space is calculated using three algorithms (Euler, Euler-Cromer, and Leapfrog methods). The errors associated with these algorithms are explained using techniques of numerical analysis. Results show that the Leapfrog method converges to the analytic solution of the equations of motion of the SHO the fastest. This method will be used to calculate the trajectory of the Galactic CRs. [Preview Abstract] |
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FP1.00016: Preliminary Results For the Distribution of Observable Pulsars Within the Galaxy Frank Ceballos, Matthew Benacquista We present preliminary results from an attempt to predict the distribution of observable pulsars within the Galaxy. This work is intended to provide some indication of the likelihood of finding a pulsar outside of the Galactic plane. We model the population of pulsars by considering the birth of stars within the disk of the Galaxy and evolving them to the present time. We include a model of the spatial distribution of stars in the disk, the star formation rate, the initial mass function, and the kick velocities given to the neutron star during the supernova event. Following the supernova event, we propagate the neutron star through a model of the Galactic potential to obtain the present-day distribution of pulsars. [Preview Abstract] |
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FP1.00017: Mapping of the Moon in the Ultraviolet: the Lyman Alpha Mapping Project D.G. Horvath, K.D. Retherford, G.R. Gladstone, S.A. Stern, A.F. Egan, P.F. Miles, J. Wm. Parker, T.K. Greathouse, M.W. Davis, D.C. Slater, D.E. Kaufmann, M.H. Versteeg, P.D. Feldman, D.M. Hurley, W.R. Pryor, A.R. Hendrix The Lyman Alpha Mapping Project (LAMP) is an ultraviolet (UV) spectrograph on the Lunar Reconnaissance Orbiter (LRO) that is designed to map the lunar albedo at far-UV wavelengths. LAMP primarily measures interplanetary HI Lyman-alpha sky-glow and FUV starlight reflected from the night-side lunar surface, including permanently shadowed regions (PSRs) near the poles. Dayside observations are also obtained. Calibration data, collected monthly, will monitor instrument functionality. Brightness maps sorted by wavelength (including the Lyman-alpha wavelength of 121.6 nm) are reported for the polar regions, with a few regions of interest reported in more detail. LAMP's spectral range of 58 nm to 196 nm includes a water ice spectral feature near 160 nm, which provides a diagnostic tool for detecting water on the lunar surface that is complementary to recent discoveries using infrared and radio frequency techniques. Progress towards producing far-UV albedo maps and searching for water ice signatures will be reported. We'll discuss how LAMP data may address questions regarding how water is formed on the moon, transported through the lunar atmosphere, and deposited in the PSRs. [Preview Abstract] |
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FP1.00018: Low-Energy electrons in Saturn's Magnetosphere Anna DeJong, James Burch Electron data from the Cassini Electron Spectrometer (CAPS-ELS) are examined from July 14, 2004 to April 30, 2010. When Cassini is within $\pm10^o$ latitude of the equator a peak in the low energy electrons ($\sim100 eV$) is observed to extend from approximately 7 to 8.5 R$_S$. We find this low energy peak, which has been reported in total density by Wahlund et al. [2005], to be associated with localized plasma injections. When the electrons are separated by pitch angle there is difference in the longitudinal and local time dependences. This result indicates that there is a large source of interchange instability at 330$^{\circ}$ SLS3 and in the nightside of the Saturnian magnetosphere. [Preview Abstract] |
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FP1.00019: X-ray Eclipses in the 2010 January Outburst of the Recurrent Nova U Scorpii? Laura Vega, Laura McMaster, Marilyn Moore, Sabrina Engelhardt, Eric Schlegel, Ashley Pagnotta The recurrent nova U Scorpius (U Sco) is an eclipsing system with an orbit inclination of 80-83 degrees and for which the secondary blocks the light from the primary for $\sim$0.1 of the orbit in the optical. A clean test of the origin of the X-ray flux in the burst is made possible by U Sco: if X-rays arise from the proximity of the white dwarf, then we must detect X-ray eclipses and the exact shape of the eclipse determines the nature of the distribution of emitting matter. We describe the comparison of X-ray spectra obtained in and out of eclipse. [Preview Abstract] |
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FP1.00020: ABSTRACT WITHDRAWN |
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FP1.00021: Empirical Model for Ion Flows Around Jupiter During the Galileo Mission Austin Egert, Jared Bell, Hunter Waite Jupiter's intense magnetic field is second only to the solar magnetic field. This intense field surrounds and permeates a robust magnetospheric plasma that co-rotates with the planet out to several Jovian (radii), R$_{J}$, until a multitude of processes cause the co-rotating plasma to lag (Hill [1979]). The complex plasma dynamics produce a system of field aligned currents and electric fields that map down into Jupiter's upper atmosphere. It is currently believed that this mapping of these convection electric fields play a dominant role (if not the dominant role) in determining the energy balance for Jupiter's entire upper atmosphere. For this poster, we present an empirically based model of the Jovian plasma motion, focused on reproducing in qualitative and quantitative terms the measured ion flows from Galileo (Krupp et al. [2007]). Using this empirical ion flow model, we plan to construct a semi-empirical model for the mapping of convection electric fields into Jupiter's upper atmosphere. This electric field model will be used to drive ion dynamics and thermal balance calculations in a newly developed Jovian Global thermosphere-ionosphere model (J-GITM), which will be used to support the upcoming Juno mission. [Preview Abstract] |
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FP1.00022: Three Dimensional Structure of CIRs at 1 AU Thomas Broiles We have studied CIRs at 1 AU over two solar cycles, by identifying 153 CIRs from the start of 1995 to the end of 2008 using ACE and Wind bulk plasma and magnetic field data. We used this list to study the bulk properties and the three dimensional structure of CIRs using minimum variance analysis. The planar magnetic structure of CIRs form along the Parker spiral and with an approximate, mean tilt out of the ecliptic of 20\r{ }. They also have a mean minimum width of 0.25 AU. At the ecliptic, CIRs do not always form with tilt out of the ecliptic opposing the hemisphere that their coronal hole originated in. We have also compared Lee's prediction of solar wind deflection to observations and found a relationship does exist, but not as expected by theory. [Preview Abstract] |
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FP1.00023: Photometry of Standard Stars and Open Star Clusters Amanda Jefferies, Peter Frinchaboy Photometric CCD observations of open star clusters and standard stars were carried out at the McDonald Observatory in Fort Davis, Texas. This data was analyzed using aperture photometry algorithms (DAOPHOT II and ALLSTAR) and the IRAF software package. Color-magnitude diagrams of these clusters were produced, showing the evolution of each cluster along the main sequence. [Preview Abstract] |
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FP1.00024: Warning times for potentially hazardous long-period comets Susan Martinez, Dan Boice, Walter Huebner Southwest Research Institute and Los Alamos National Laboratory are developing a program to avert collisions of potentially hazardous objects with Earth. Aggressive methods and continuous alertness will be needed to defend against objects with short warning times. In this study we discuss the threat posed by long-period comets. Although relatively rare but large and fast moving, their detection cannot be predicted because of their long orbital periods. For example, Comet C/1983 H1 was discovered on 27 April 1983, and passed Earth at a distance of 0.0312 AU on 11 May 1983. It has an orbital period of 963.22 years. We have developed a database of long-period comets over the last decade that includes dates of discovery, perihelion passage, perigee passage, and the associated distances. We summarize results of anticipated warning times for long-period comets to present nominal and worst-case scenarios for these potentially hazardous objects, given advances in modern telescopic facilities searching for such objects. [Preview Abstract] |
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FP1.00025: Super Storm Dependence upon Solar-Wind-Magnetosphere Coupling George Clark, Jerry Goldstein, Joerg-Micha Jahn Statistical relationships were explored between super geomagnetic storms (Dst $<$ -200 nT) and solar wind parameters. We consider coupling parameters such as the Akasofu epsilon parameter, total energy input into the magnetosphere, Kan and Lee electric field, solar wind electric field, and the IMF components. Correlations between super storms and the solar wind help us understand how energy is transferred into the magnetosphere. Data was obtained using the OMNIWeb data center. OMNIWeb complies magnetic field and plasma measurements from a suite of spacecraft (ACE, Geotail, Wind, IMP-8, ISEE3) and Dst measurements from the NOAA and Kyoto data hubs. Results show a strong correlation (r $>$ 0.8) between the solar wind electric field and IMF components as a function of Dst. Moderate correlations (r $>$ 0.6) exist upon the Akasofu epsilon parameter, total energy input, and Kan and Lee electric field with Dst. The total energy input during a super storm is about a factor of two greater than a normal storm and about a factor of six greater in comparison to the solar wind electric field. Results also suggest a natural separation between normal storms and super storms, which suggest different energization mechanisms. Practical applications of this study relate to radiation belt dynamics which threaten our spacecraft and astronauts. [Preview Abstract] |
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FP1.00026: Levenberg-Marquardt Algorithm Applied to Cassini-CAPS Corotational Data Roberto Livi, Jerry Goldstein, Jim Burch, Anna DeJong, Frank Crary, Dave Young, Fran Bagenal Plasma corotation flow around Saturn is analyzed using a non-linear, least squares fitting routine based on the Levenberg-Marquardt algorithm, tailored specifically for data from the Cassini Plasma Spectrometer (CAPS). The program assumes the plasma to consist of two species, a light group ($H^+$) and a water group ($W^+$) corotating at the same velocity. It is therefore designed to automatically model a one-dimensional Maxwell- Boltzmann distribution (one for each species) to a large data set and derive the corresponding densities, velocities, and temperatures using minimal computer resources for faster computation. Preliminary results derived by the algorithm are presented for six years of CAPS data, from all longitudes, between 3-10 Saturn radii ($R_S$) and $\pm$10$^{\circ}$ latitude. [Preview Abstract] |
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FP1.00027: Mapping the Galaxy with LISA Jose Mckinnon, Matthew Benacquista We have developed a Matlab Fisher MAtrix code in order to study how LISA observations of Galactic compact object binaries can be used to better understand Galactic structure. The code simulates the results of data analysis and estimates the variance and covariance of recovered parameters. We will use the recovered parameters to estimate Galactic structure. Here we present first results applied to a standard Galaxy model. [Preview Abstract] |
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FP1.00028: Effect of Porphyrins Bound to Tubulin Dimers Brady McMicken Photosensitizers are photoactive molecules that when irradiated with UV or visble light initiate photochemical or photophysical reactions that may affect the environment surrounding them, including proteins to which they are attached. Our photosensitizers of interest are the anionic porphyrin, mesotetrakis (sulfonatophenyl) porphyrin (TPPS), which bind noncovalently to Tubulin dimers. This is significant since we can then irradiate the porphyrin and cause a change in the geometry of the protein to specifically affect its function. What has yet to be fully understood is the mechanism of the photochemical reaction and unfolding of the protein after irradiation. A combination of various spectroscopic methods can give us insight into the structural changes of the photosensitizer and the protein and characterize the conformational changes produced in the protein. The study is completed by computational simulations of the docking as well as the unfolding of the protein. [Preview Abstract] |
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FP1.00029: Chaos Theory and Protein Dynamics James Bui, James Clarage Chaos theory, commonly known as the butterfly effect, states that a small change in a complex system may cause large changes in the system as time moves forward. This phenomenon was first discovered by Henri Poincare in the 1880's. The computer programs NAMD, VMD (Visual Molecular Dynamics) and Mathematica were used to calculate the movements and graphically analyze the trajectories of the protein ubiquitin. A small change was applied to a single atom's initial position in the x-coordinate to see how it would affect the future dynamics and trajectory of the protein. Our findings indicate an exponential divergence from the controlled trajectory with a Lyapunov exponent = 10.5 [1/ps]. In other words after less than a picosecond (trillionth of a second) the dynamics of a small biophysical system is no longer predictable, even though the underlying Newtonian physical laws are completely deterministic. [Preview Abstract] |
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FP1.00030: Near Infrared Optical Properties of Whole Human Blood and Blood Containing Nanoparticulates Lawrence C. Mimun, Brian Yust, Kelly L. Nash, Dhiraj K. Sardar Whole human blood is optically characterized in the near infrared (NIR) with and without the addition of nanocrystals. The optical properties were obtained using the double-integrating sphere technique at the Nd excitation wavelength of 808 nm. Y$_{2}$O$_{3}$ and Nd$^{3+}$:Y$_{2}$O$_{3}$ nanoparticles were added in predetermined amounts to water, blood plasma, and whole blood samples, from which a computational analysis was conducted using the Kubelka-Munk calculational method, the Inverse Adding Doubling Method, and the Magic Light Monte Carlo Method to characterized the optical properties such as the absorption ($\mu _{a})$ and scattering coefficients ($\mu _{s})$ and the scattering anisotropy (g). Through comparison with control samples, the optical properties of each component (blood, plasma, and nanoparticles) can be determined individually, thus illuminating any changes due to the biological environment. The emission from the Nd$^{3+}$:Y$_{2}$O$_{3}$ particles through the blood is also detected thus exhibiting their usefulness as real world biological markers. [Preview Abstract] |
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FP1.00031: How Do Single Point Mutations Impact Protein Folding in Parkinson's Disease Olivia Wise-Scira, Andrew Roque, Liang Xu, Orkid Coskuner Although the structures of the wild type (WT) and mutants (A53T, A30P, E46K) of $\alpha $-synuclein ($\alpha $-syn) proteins related to Parkinson's disease have been studied extensively using both experimental and theoretical tools, the relationships between the structural properties and thermodynamic preferences at a molecular level with dynamics are unknown. Such an understanding is required for accessing detailed knowledge regarding to the ``early aggregation and monomer'' hypothesis in Parkinson's disease. We investigated the impact of these single point mutations on the structures and conformational preferences of $\alpha $-syn monomers in aqueous solution as well as the impact of the aqueous solution environment on the proteins. Obtained qualitative and quantitative results provide new insights into the structure-function relationships of these proteins and help us to understand the molecular mechanism hidden behind the ``early aggregation and monomer'' hypothesis. Our results show that the tertiary structure of the $\alpha $-syn proteins varies significantly with dynamics, however, this variability is not easily reflected in the changes of the relative amounts of the secondary structural components. The obtained structures also demonstrate that a single point mutation can have a significant effect on protein folding. The structures of each of the WT, A53T, A30P, and E46K $\alpha $-syn monomers differ from each other throughout and the presence of aqueous solution significantly impacts the $\alpha $-syn protein structures. [Preview Abstract] |
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FP1.00032: The Maximum Solubility of Cholesterol in POPC/POPE Lipid Mixtures Serkan Balyimez, Juyang Huang Cholesterol is a major constituent of cell membranes and has many important cell functions. The maximum solubility of cholesterol in a lipid bilayer is the highest mole fraction of cholesterol that can be incorporated into a lipid bilayer before cholesterol crystals precipitate. The maximum solubility can provide valuable information about cholesterol-phospholipid interaction. In this study, the maximum solubility of cholesterol in mixtures of POPE/POPC lipid bilayer has been investigated systematically using a cholesterol oxidase (COD) reaction rate assay. The maximum solubility of cholesterol was determined to be 67 mol\% in POPC bilayers and 50 mol\% in POPE bilayers. In mixtures of POPE/POPC, the maximum solubility of cholesterol increases linearly as a function of the ratio POPC/(POPE+POPC). The data indicates that cholesterol prefers the large headgroup lipid (POPC) over the small headgroup lipid (POPE) and the maximum solubility increases with the population of large headgroup lipid (POPC), which are consistent with the Umbrella Model. Previously, it has been suggested that cholesterol may form a ``hexagonal'' regular distribution pattern at the maximum solubility limit in POPE bilayers and a ``maze'' pattern at the maximum solubility in POPC bilayers. It is still unclear whether domains of these patterns exist at the maximum solubility limit in POPE/POPC mixtures, and more investigation is needed. [Preview Abstract] |
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FP1.00033: Mining X-ray diffuse scattering images for evidence of protein dynamics Mary Faltaous, James Clarage For years biologists and biochemists have used images obtained from X-ray diffraction to determine the most probable tertiary structure of a protein. However the data typically analyzed represent only about 0.1\% of the total photons collected in one image. This project focuses on the 99.9\% of potential information that is usually discarded in experiments. Researchers usually focus on the strongest part of the X-ray signal, the so-called ``Bragg Peaks.'' The remaining negative space around the peaks may have evidence about the movement and dynamics of the protein in the cell. One hopes that this can aid in the complete knowledge of the form of the protein and that can, in return, clarify its function. [Preview Abstract] |
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FP1.00034: Dynamics of Small Peptides: Comparison of NMR Relaxation Experiments with Molecular Dynamics Simulations David Torres, Elizabeth Gonzalez, Michelle Steiger, James Clarage Understanding biological molecules from differing perspectives and obtaining results which concur with one another has been a goal of researchers for years. We applied both theoretical and experimental approaches to study the biophysics and dynamics of a small biological molecule, the dipeptide Alaninephenylalanine (Ala-Phe). For our theoretical approach we used the computer programs NAMD and VMD to place the dipeptide in a box of water and simulate atomic motions for every atom in the system for 100 nanoseconds. From these simulations we can predict correlation times for the atomic movements. Experimentally, relaxation times (T1, T2) were collected using Nuclear Magnetic Resonance (NMR). Comparing theory with experiment, we found similarities in the trends of correlation times for various atoms in the molecule. [Preview Abstract] |
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FP1.00035: Light Scattering as an Indicator of Protein Aggregate Size Jeremiah Babcock, Rolando Valdez, Lorenzo Brancaleon Biophysical studies have shown that solutes like proteins undergo aggregation through specific pathways that often lead to long polymeric structures called fibrils. The knowledge of the size of early-stage protein aggregates (oligomers) has an important bearing on the elucidation of the dynamics of the process of protein unit combinations. In this study, bovine serum albumin, a well-characterized model protein known to polymerize in alkaline conditions in the normal (N) to basic (B) was incubated at pH 9.0 for longer than eight days. Particle growth in solution was monitored by resonance and non-resonance light scattering in absorption spectroscopy, and concurrently measured by tapping mode atomic force microscopy (AFM) methods to yield BSA oligomer size distributions through the growth lag phase of elongated fibrils. Results show that BSA concentrated to one mg/mL rapidly forms spherical aggregates, which preferentially come together to form flexible polymers with periodic structures. [Preview Abstract] |
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FP1.00036: Automated Microorganism Detector Pelham Keahey, Will Hardy, Mason Cradit, Steven Solis, Andrea Holland, Gerry Wade The detection and identification of bacteria in blood samples is crucial for treating patients suspected of having a blood infection. Current hospital methods for pathogen detection are time-consuming processes with multiple steps. This project's goal was to develop an efficient biomedical device to detect bacterial growth in blood samples, based on Gerald J. Wade's 1979 invention (US patents 4250266 and 4267276). Detection was accomplished using a system of electronics to examine the change in the electrochemical properties of a sample in response to bacterial growth, by measuring the sample's electrical charging and charge dispersion characteristics. After initial trials, it was found that a sample yielded consistent voltage measurements of approximately 200 millivolts prior to any detectable microbial growth. The first species tested, \textit{Escherichia coli} (\textit{E. coli}), was detected 11.7 hours after its inoculation in a culture bottle at a concentration of approximately 5-10 organisms per milliliter. In future tests, it is expected that detection times will vary in proportion to the growth rate of each species. [Preview Abstract] |
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FP1.00037: A Study of the Accuracy and Precision Among XRF, ICP-MS, and PIXE on Trace Element Analyses of Small Water Samples Sahil Naik, Ritish Patnaik, Venkata Kummari, Lucas Phinney, Mangal Dhoubhadel, Aaron Jesseph, William Hoffmann, Guido Verbeck, Bibhudutta Rout The study aimed to compare the viability, precision, and accuracy among three popular instruments - X-ray Fluorescence (XRF), Inductively Coupled Plasma Mass Spectrometer (ICP-MS), and Particle-Induced X-ray Emission (PIXE) - used to analyze the trace elemental composition of small water samples. Ten-milliliter water samples from public tap water sources in seven different localities in India (Bangalore, Kochi, Bhubaneswar, Cuttack, Puri, Hospet, and Pipili) were prepared through filtration and dilution for proper analysis. The project speculates that the ICP-MS will give the most accurate and precise trace elemental analysis, followed by PIXE and XRF. XRF will be seen as a portable and affordable instrument that can analyze samples on-site while ICP-MS is extremely accurate, and expensive option for off-site analyses. PIXE will be deemed to be too expensive and cumbersome for on-site analysis; however, laboratories with a PIXE accelerator can use the instrument to get accurate analyses. [Preview Abstract] |
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FP1.00038: Structural and Thermodynamic Properties of Amyloid-$\beta $ Peptides: Impact of Fragment Size T. Kitahara, O. Wise-Scira, O. Coskuner Alzheimer's disease is a progressive neurodegenerative disease whose physiological characteristics include the accumulation of amyloid-containing deposits in the brain and consequent synapse and neuron loss. Unfortunately, most widely used drugs for the treatment can palliate the outer symptoms but cannot cure the disease itself. Hence, developing a new drug that can cure it. Most recently, the ``early aggregation and monomer'' hypothesis has become popular and a few drugs have been developed based on this hypothesis. Detailed understanding of the amyloid-$\beta $ peptide structure can better help us to determine more effective treatment strategies; indeed, the structure of Amyloid has been studied extensively employing experimental and theoretical tools. Nevertheless, those studies have employed different fragment sizes of Amyloid and characterized its conformational nature in different media. Thus, the structural properties might be different from each other and provide a reason for the existing debates in the literature. Here, we performed all-atom MD simulations and present the structural and thermodynamic properties of A$\beta _{1-16}$, A$\beta _{1-28}$, and A$\beta _{1-42}$ in the gas phase and in aqueous solution. Our studies show that the overall structures, secondary structures, and the calculated thermodynamic properties change with increasing peptide size. In addition, we find that the structural properties of those peptides are different from each other in the gas phase and in aqueous solution. [Preview Abstract] |
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FP1.00039: Structure, function and folding of phosphoglycerate kinase are strongly perturbed by macromolecular crowding. Antonios Samiotakis, Apratim Dhar, Simon Ebbinghaus, Lea Nienhaus, Dirar Homouz, Martin Gruebele, Margaret Cheung We combine experiment and computer simulation to show how macromolecular crowding dramatically affects the structure, function and folding landscape of phosphoglycerate kinase (PGK). Fluorescence labeling shows that compact states of yeast PGK are populated as the amount of crowding agents (Ficoll 70) increases. Coarse-grained molecular simulations reveal three compact ensembles: C (crystal structure), CC (collapsed crystal) and Sph (spherical compact). With an adjustment for viscosity, crowded wild type PGK and fluorescent PGK are about 15 times or more active in 200 mg/ml Ficoll than in aqueous solution. Our results suggest a new solution to the classic problem of how the ADP and diphosphoglycerate binding sites of PGK come together to make ATP: rather than undergoing a hinge motion, the ADP and substrate sites are already located in proximity under crowded conditions that mimic the in vivo conditions under which the enzyme actually operates. [Preview Abstract] |
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FP1.00040: An approach for detecting low frequency non-stationarity present in LIGO science data Robert Stone, Soma Mukherjee One of the important detector characterization issues in gravitational wave (GW) searches is the seismic background. ``NoiseFloorMon'' is a data monitoring tool (DMT) that has been developed to help characterize the effect of seismic activity on the gravitational wave channels at both Laser Interferometer Gravitational-wave Observatory (LIGO) sites, and to identify instances of low-frequency non-stationarity. Cross-correlation measurements between the GW channel and seismic sensors that exceed a median-based threshold serve as pointers to time intervals of non-stationarity. Highest threshold crossings are recorded on a daily basis and the events are followed-up using time-frequency visualization methods of both the GW channel as well as the environmental channels involved. These events are also compared with existing figures of merit and data quality flags to find further correlations with other possible sources across the detector and in the environment. The method is illustrated with data from the fourth LIGO science run. [Preview Abstract] |
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FP1.00041: Surface chemistry of functionalized carbon nanotubes and their nanocomposites Z.P. Luo, L. Carson, A. Oki, L. Adams, N. Soboyejo, E.G.C. Regisford, A. Holzenburg Carbon nanotubes (CNTs) have been well recognized as a promising material due to their extraordinary mechanical, thermal and electrical properties for diverse applications. However, their behavior of hydrophobicity and chemical inertness, which cause tangling or poor dispersion, limits their commercial applications. In order to overcome the problem of tangling caused by CNT intrinsic van der Waals forces during the composite fabrication, a chemical functionalization process was introduced to achieve a better degree of dispersion, which is a critical factor determining the composite performance. This work is on the characterization the functionalized CNTs and their nano composites using advanced analytical transmission electron microscopy (TEM), including scanning TEM and energy dispersive spectroscopy for chemical compositional analysis using nanometer sized electron beam, electron energy-loss spectroscopic elemental mapping, and electron tomography for 3D reconstruction. It was found the functionalized CNTs showed better chemical bonding with matrices in the nanocomposites. [Preview Abstract] |
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FP1.00042: Enhancing Optical Anisotropy and Thermal Stability of Liquid Crystals by Nanoparticles Karen Vardanyan, Robert Walton, Richard Jimenez The proper electro-optical performance of devices utilizing Liquid Crystal materials require high optical/dielectric anisotropy, low threshold voltage, fast switching, and high thermal stability. Among these devises are liquid crystal displays, guided-wave switches for wavelength division multiplexing, etc. One can tailor LC material parameters for a particular application by using chemical synthesis or mixing several LC materials. However, in the most cases, enhancing one parameter can cause the other parameters to change as well and mostly in undesirable direction. For instance, increase of dielectric anisotropy of the materials usually causes increase in the threshold voltage and switching times. Moreover, in many cases the enhancement process accompanies with decrease in the thermal stability of the materials. We obtained novel binary mixtures of certain type nematic LC with gold nanoparticles. We found that at certain concentrations of gold the dielectric anisotropy, i.e. birefringence, of LC materials increase twice, while the threshold voltage and switching time remain low. More importantly, at the same concentrations of gold the thermal stability of the materials increases in about 15 degrees of Celsius. [Preview Abstract] |
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FP1.00043: Apparatus for the analysis of surfaces in gas environments using Positron Spectroscopy Suman Satyal, Lawrence Lim, Vibek Joglekar, Sushant Kalaskar, Karthik Shastry, Alex Weiss Positron spectroscopy performed with low energy beams can provide highly surface specific information due to the trapping of positrons in an image potential surface state at the time of annihilation. Here we describe a spectrometer that will employ differential pumping to enable us to transport the positrons most of the way from the source to the sample under high vacuum and then to traverse a thin gas layer surrounding the sample. The positrons will be implanted into the sample at energies less than $\sim $10 keV ensuring that a large fraction will diffuse back to the surface before annihilation. The Elemental content of the surface interacting with the gas environment will then be determined from the Doppler broadened gamma spectra. This system will include a time of flight positron annihilation induced Auger spectrometer (TOF-PAES) which correlates with the Doppler measurements at lower pressures. [Preview Abstract] |
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FP1.00044: Sharma and Fulde-Farrell-Larkin-Ovchinnikov states in an optical lattice Zlatko Koinov, Rafael Perez, Mauricio Fortes We study an imbalance mixture of atomic Fermi gas of two hyperfine states loaded into an optical lattice. We solve the self- consistent equations for the filling factors and the gap equation to investigate the existence of Sharma and Fulde-Farrell-Larkin-Ovchinnikov (FFLO) superfluid states assuming a contact interaction between the atoms (Hubard model). The order parameter in the case of Fulde-Farrell-Larkin-Ovchinnikov (FFLO) superfluid is chosen to be $Delta_{\textbf{q}}=\Delta_0 \exp\left(\imath \textbf{q.r}\right)$, where $2\textbf{q}$ is the pair momentum in a single plane wave FFLO state. [Preview Abstract] |
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FP1.00045: A first principles study of noble metal-doped silicon nanocrystals Si$_{n-1}$M (n = 75 and 150 and M = Cu, Ag, Au) Cedric Mayfield, Muhammad Huda Silicon nano-structures can have important roles in many useful applications, such as in nano-scale energy conversion materials, as nano-detectors of gas particles or as thermoelectric materials. To achieve efficient performance of these nano-devices, electronically tailored nano-materials are needed. For this a thorough understanding of both doped and undoped nano-structures is essential. Here we will present results of our first principles spin polarized electronic structure calculations of noble metal atom doped silicon nanocrystals using a hybrid density functional theory method (B3LYP-DFT) and a LanL2DZ basis set. The nanocrystals are used here as a test group, and are based on three different isomers of bulk silicon: diamond, wurtzite, and BC8. Geometry optimizations of the pure Si$_{n}$ nanocrystals were performed for spin magnetic moments of s=0 \textit{$\mu $}$_{B}$ and s=2 \textit{$\mu $}$_{B}$ for each isomer. Then the substitutional doping of M atom was done separately at the inside and at the surface of the nanocrystals. The doped nanocrystals' geometries were also optimized for spin magnetic moments s=1 \textit{$\mu $}$_{B}$ and s=3 \textit{$\mu $}$_{B}$. For the bigger nanocrystals, the energy differences between the two spin states are very small. Binding energies and HOMO-LUMO gaps were calculated and a comparative analysis of the pure and doped silicon nanocrystals will be presented. [Preview Abstract] |
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FP1.00046: Photocatalytic Decomposition of Water: Next Generation Fuel Source Keegan Hanks Photocatalysis of hydrogen from water has been vastly concerned with using a Pt/Ru co-catalyst for the generation of hydrogen from water and molecular co-catalysts with hydrocarbon precursors. This process contains separate nucleation sites and proves to have a limited efficency. Molecular and nanoparticle co-catalysts have also been considered showing an improvement in the applicability of this water-splitting process to produce a clean and renewable fuel from a simple and green reaction process. Recent research has vastly improved the feasibility of the nanoparticle co-catalyst based process as a clean and reliable resource for fuel. I present herein a theoretical application of composite nanoparticles using transition metal semiconductors. I propose the composite nanostructures as the catalylst and the co-catalyst in one nanoparticle rather than an expensive Pt co-catalyst and molecular catalyst combo. With this approach, our goal is to develop a single beaker synthesis of these nanoparticles and place them in water under artificial sunlight in our newly developed laboratories here on campus to characterize the nanoparticles and analyze the efficency of hydrogen generation. [Preview Abstract] |
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FP1.00047: Study of Bulk Modulus in Zincblende Nitrogen doped Gallium Phosphide Alloys Using Density Functional Theory Brandon Butler, Muhammad Huda Solar energy is seemingly the most attractive prospect in renewable energy technology. The problem arises in the ability to convert and store this source of energy into usable electrical energy. Development of solar cell materials has become an object of focus among scientists. In this work, a theoretical analysis will be employed to a study investigating elastic properties, namely bulk modulus, and electronic properties of GaP alloys doped with varying concentrations of nitrogen. The total energy calculation for each periodic system has utilized the principles of density functional theory (DFT) and its' generalized gradient approximation (GGA). Once the total energy calculation was performed, we obtained the bulk modulus, B$_{0}$, and its first pressure derivative, B$_{0}$', by fitting the Birch-Murnaghan equation of state. The bulk modulus was calculated for a few extensively studied materials, namely GaN and un-doped GaP. The results of these prototype calculations compared well with the published experimental values as well as other GGA calculated values. Our computational method of determining the bulk modulus was then used for the GaP$_{1-x}$N$_{x}$ alloy with varying concentrations of nitrogen. The bulk modulus for these alloys was found to be notably higher than un-doped GaP and further increases with higher concentrations of nitrogen. [Preview Abstract] |
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FP1.00048: Study of novel configuration of columnar defects in the high temperature superconductor YBa$_{2}$Cu$_{3}$O$_{7}$ Lauren Dorsett, Andra Troncalli, Lisa Paulius, Wai -K Kwok, Austin Howard, Nicholas Cornell, Anvar Zakhidov Columnar defects have proven to be highly effective at pinning vortices in high temperature superconductors. However, most studies have been performed with the defects oriented either \textit{perpendicular} or at large angles relative to the superconducting Cu-O planes. Our study is novel due to the introduction of defects \textit{parallel} to the superconducting planes. We will discuss the effect of the defects on the vortex pinning anisotropy of the YBa$_{2}$Cu$_{3}$O$_{7-\delta }$ single crystals. [Preview Abstract] |
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FP1.00049: Temperature Dependencies of Linewidths, Positions, and Line Shifts of Spectral Transitions of Trivalent Neodymium Ions in Ceramic Nd3+:Y2O3 Francisco Pedraza, Edward Khachatryan, Robert Dennis, Kelly Nash, Dhiraj Sardar Effects of temperature on widths and shifts of the spectral lines of Nd$^{3+}$ in Y$_{2}$O$_{3}$ polycrystalline ceramic have been investigated. The spectral lines corresponding to the inter-Stark transitions R$_{1} \quad \to $ Y$_{1}$ (1074 nm) and R$_{1}\to $ X$_{3}$ (914 nm) within the $^{4}$F$_{3/2} \quad \to \quad ^{4}$I$_{11/2}$ and $^{4}$F$_{3/2} \quad \to $ $^{4}$I$_{9/2}$ transitions, respectively, have been studied. The widths of these lines and their shifts have been measured as a function of temperature in 10K- 300K range. The spectral linewidths of both transitions are found to increase with increasing temperature. This research was supported by the National Science Foundation Grant No. DMR-0934218. [Preview Abstract] |
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FP1.00050: Ferroelectric BaTiO$_{3}$ thin film synthesis on Ni substrates by pulsed laser deposition with varying oxygen atmosphere conditions E. Silva, J. Liu, M. Liu, G. Collins, C.L. Chen A KrF excimer laser of 248nm wavelength was used to fabricate ferroelectric Barium Titanate (BaTiO$_{3}$) on nickel substrates. A high vacuum chamber base pressure of $\sim$3.0x10$^{-7}$ Torr was obtained for each sample and a laser repetition rate of 10Hz with an energy of 600mJ was used. The first film was synthesized by depositing BTO for 60min at 850 $^{\circ}$C under HV; prior to annealing the oxygen atmosphere was set to 250mTorr. The second film was deposited at 850$^ {\circ}$C under HV for 1 min followed by an increase in oxygen atmosphere to 250mTorr, resuming deposition for 59min. The third film was deposited under HV at 200$^{\circ}$C for 1min, the oxygen atmosphere and temperature were then set to 250mTorr and 850$^{\circ}$C followed by film deposition for an additional 59min. All three samples were annealed at 840$^{\circ}$C for 15 min and lowered to 20$^{\circ}$C at a rate of 3$^{\circ}$C per min. Hysteresis measurements were obtained for the samples with a Radiant Technologies inc. RT6000HVS system. It was observed that both the first and second films had a hysteresis loop in close resemblance to paraelectric materials while the third film showed an improved square shape hysteresis loop, indicative of ferroelectric properties. [Preview Abstract] |
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FP1.00051: Capturing the Potential of Dye-Sensitized Solar Cells James Benson Dye-sensitized solar cells are a continually developing type of low-cost solar cells that have commercial efficiency around 6-10\%. The proposed research here will be focusing on the photo-bleaching and improving techniques for electron transport. Nature has given us a goal to reach towards with proven techniques for converting light into energy with around 30-40\% efficiency, however, chlorophyll, the light absorber in plants, is expensive and it is not practical to make solar cells with only chlorophyll as the absorber. One such alternative to chlorophyll is phthalocyanines which is a common industrial dye used in many applications. This dye has a common similar ring without the long phytol chain that chlorophyll has. Previous research has shown that encapsulating organic dyes can magnify the properties of dye from the increased concentration with a possible benefit of stabilizing the dye allowing it to slow down the photo bleaching significantly. Likewise, such encapsulation may help with thermal stability since many dye-sensitized solar cells require a liquid or gel solution that is sensitive to thermal expansion. Many researchers are also finding new ways to encapsulate the dyes or dope the p-n layers with nano and meso tubes to help with electron transport or build the p-n layers right in the tubes. This allows for countless layers and an overall more efficient design. [Preview Abstract] |
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FP1.00052: Study of Narrowband Noise in Gravitational Wave Interferometers Thilina Shihan Weerathunga Narrowband noise in LIGO (Laser Interferometer Gravitational Wave (GW) Observatory) restricts usability of GW data for astrophysical searches and reduces sensitivity of the searches. Attempts to remove these narrowband noise features in GW data have been in the works for a long time. All the line removing algorithms require a complete list of lines and line information such as central frequency and width of lines, present in the data. The problem with preparation of such a database is the fact that the lines are non-stationary and the non-stationarity of the lines is unpredictable depending on the operating conditions of the instrument and can occur both on a short time-scale as well as on a long time-scale. This work presents a new technique for dynamically identifying and cataloguing the narrow band line features present in GW data. [Preview Abstract] |
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FP1.00053: Modeling signals in gravitational wave interferometric data Gamage Dannangoda The current generation of gravitational wave detectors e.g. LIGO (www.ligo.caltech.edu) are taking data in the ``science'' mode. The data received at the output is a mixture of many different kinds of signals of instrumental and environmental origin (the detector ``noise''). This study focuses on how to model these spurious signals so that they can later be subjected to further analysis to classify them into groups. Signals from different instrumental and environmental sources bear different signatures and thus have different waveforms. A low order ARMA can model these signals. The method is demonstrated by application on real data. [Preview Abstract] |
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FP1.00054: Smarandache's Minimum Theorem in the Einstein Relativistic Velocity Model of Hyperbolic Geometry Catalin Barbu We present a proof to the Smarandache's Minimum Theorem in the Einstein Relativistic Velocity Model of Hyperbolic Geometry. [Preview Abstract] |
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FP1.00055: Applications of the diffraction and interference of light and electronic waves Cristian Bahrim, Robert Lanning As part of a NSF sponsored program, called STAIRSTEP, at Lamar University we work on improving the basic knowledge of our physics majors in topics with broader impact in various areas of science and engineering [1]. The purpose is to facilitate a deeper understanding of some fundamental concepts in the field of optics through hands-on experience [2]. We choose to study the interference/diffraction of light and matter waves, because of its fundamental importance in physics with many applications. We target multiple goals in our field of study such as to understand the formation of electronic waves (wave packets) and their interaction with atoms in crystals (electron diffraction); the Fourier analysis of light with applications in spectroscopy, etc. We can show that a crystal lattice Fourier transforms the sinusoidal waves associated to free electrons fired toward the crystal. Our studies led to a simple and instructive recipe for discovering the arrangement of atoms in crystals from the analysis of the diffraction patterns produced by radiation or by electrons transmitted through crystals. [1] Doerschuk P. \textit{et al.}, \textbf{39th ASEE/IEEE Frontiers in Education Conference}, San Antonio 2009, M3F-1. \textbf{[2] }Bahrim C, \textbf{Innovation 2006 -- World Innovations in Engineering Education and Research}, Chapter 17, \textit{iNEER Innovation Series}, ISBN 0-9741252-5-3. [Preview Abstract] |
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FP1.00056: Comparison of GEANT4 Physics Models with Measured Beta Particle Data in Aluminum using a Strontium-90 Source Samantha Everett A transmission curve experiment was carried out to measure the range of beta particles in aluminum in the health physics laboratory located on the campus of Texas Southern University. The transmission count rate through aluminum for varying radiation lengths was measured using beta particles emitted from a low activity ($\sim $1 $\mu $Ci) Sr-90 source. The count rate intensity was recorded using a Geiger Mueller tube (SGC N210/BNC) with an active volume of 61 cm$^{3}$ within a systematic detection accuracy of a few percent. We compared these data with a realistic simulation of the experimental setup using the Geant4 Monte Carlo toolkit (version 9.3). The purpose of this study was to benchmark our Monte Carlo for future experiments as part of a more comprehensive research program. Transmission curves were simulated based on the standard and low-energy electromagnetic physics models, and using the radioactive decay module for the electrons primary energy distribution. To ensure the validity of our measurements, linear extrapolation techniques were employed to determine the in-medium beta particle range from the measured data and was found to be 1.87 g/cm$^{2}$ ($\sim $0.693 cm), in agreement with literature values. We found that the general shape of the measured data and simulated curves were comparable; however, a discrepancy in the relative count rates was observed. The origin of this disagreement is still under investigation. [Preview Abstract] |
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FP1.00057: Shape-Controllable Synthesis of Gold Nanostructure and Their Application in Surface-Enhanced Raman Scattering (SERS) Jianhui Yang, Dhiraj Sardar Noble metal nanostructures have attracted considerable attentions because of their various applications such as imaging, catalysis, sensing, SERS, diagnosis, and therapy. Shape-control provides an important strategy for designing metallic nanostructures to tailor their physical and chemical properties. Ethylenediaminetetraacetic acid (EDTA), a chelating agent, was used for the controllable synthesis of coral-shaped gold nanostructures in aqueous solution. EDTA serves not only as a reducing agent but also as a particle capping agent in the formation of coral-shaped Au nanostructures. It is found that the concentration and reaction temperature play significant effects on the formation and growth of these novel nanostructures. Moreover, these Au nanostructures show excellent SERS enhancement ability, which could serve as highly sensitive and reproductive SERS substrates for chemical and biological detection. [Preview Abstract] |
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FP1.00058: Er$^{3+}$:Y$_{2}$O$_{3}$ Fluorescence Enhancement through Energy Transfer to Plasmonic Nanoparticles Nathan Ray Rare earth (RE) and noble metal (NM) hetero-nanostructures hold promise for many unique and robust applications. The overlap of the Er$^{3+}$ $^{4}$H$_{5/2}$ fluorescence manifold with the extinction spectra of the Au surface plasmons can give rise to energy transfer between Er$^{3+}$ (donor) and plasmonic Au (acceptor). In the limit of high efficiency energy transfer, the intensity of emission from the Er$^{3+}$/Au hetero-nanostructure becomes significantly more intense than the emission of Er$^{3+}$ alone. The quantum efficiency of the combined system, in the limit of high energy transfer, is dependent on only the scattering quantum efficiency of the Au nanoparticles. Additionally, this enhancement is a function of the quantity of gold attached. Here, we report and discuss the synthesis and spectroscopic properties of colloidal hetero-nanostructures based on a radiating plasmon model of surface plasmon coupled emission. This research was supported by the National Science Foundation PREM Grant No. DMR-0934218. [Preview Abstract] |
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FP1.00059: Comparative study of Nd$^{3+}$ in various nanocrystalline sesquioxide hosts (Nd$^{3+}$:RE$_{2}$O$_{3}$ where RE = Y, Gd, La, Yb, and Sc) Jesse Salas, Robert Dennis, Kelly Nash, Dhiraj Sardar Rare earth sesquioxides have obtained much attention for their unique optical properties. Their strong and sharp electronic transitions coupled with their long excited state lifetimes make them favorable candidates for biophotonic applications such as fluorescent biological markers. Neodymium was chosen as the fluorophore for its efficient fluorescence from 860-1200nm. This emission is ideal for deep tissue imaging and sensing as it lies within a wavelength region of minimal attenuation from biotissues. Here we report the synthesis of nanocrystalline Nd3+ doped oxides and consider their phase dependent optical properties. Room temperature absorption of Nd$^{3+}$:RE$_{2}$O$_{3}$ are reported and analyzed through the Judd-Ofelt (J-O) theoretical model to reconstruct the fluorescence linestrengths and branching ratios of the Nd$^{3+}$ (4$f^{3})$ transitions $^{4}$F$_{3/2} \rightarrow ^{4}$I$_{J}$ (J = 9/2, 11/2, 13/2, and 15/2) . Additionally, we report room temperature and 8K fluorescence, excited state lifetimes, and X-ray diffraction as a function of crystal phase. [Preview Abstract] |
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FP1.00060: Synthesis and Optical Properties of Nd$^{3+}$ in Nanocrystalline Nd$^{3+}$:BaGd$_{2}$O$_{4}$ Kenneth Ramsey, Robert Dennis, Jianhui Yang, Maogen Zhang, Dhiraj Sardar Rare earth (RE) based spinel structures (BaRE$_{2}$O$_{4})$, when doped judiciously with trivalent RE ions, are not susceptible to photobleaching, offer many sharp electronic transitions (from the visible to the NIR wavelengths) with excited state lifetimes on the order of milliseconds, and are promising for many applications ranging from high efficiency lighting, solar cells, and biomedical devices. BaRE$_{2}$O$_{4}$ has hitherto been synthesized on the nanoscale and many of the spectroscopic properties are unknown. Divalent barium, in particular, has been known to sensitize rare earth elements when incorporated into amorphous glasses. Here we report the synthesis and comparative optical properties of nanocrystalline Nd$^{3+}$:Gd$_{2}$O$_{3}$ and Nd$^{3+}$:BaGd$_{2}$O$_{4}$. Structural characterization was accomplished by scanning transmission electron microscopy, energy dispersive spectroscopy, and x-ray diffraction. The optical properties of Gd$_{2}$O$_{3}$ and BaGd$_{2}$O$_{4}$ were recorded and compared to other well known systems, such as Nd$^{3+}$:Y$_{2}$O$_{3}$. [Preview Abstract] |
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FP1.00061: Silver (Ag) nanostructure assisted fluorescence imaging Kyung-Min Lee, Arup Neogi, Minjung Kim, Bongsoo Kim, Rafal Luchowski , Zygmunt Gryczynski, Nils Calander, Tae-Youl Choi We developed a novel cell imaging technique using nanoengineered plasmonic platform which consists of a combined structure of silver (Ag) nanowire (NW) and nanodot (ND) array (NW-NDA). This novel platform can be a promising utility for optical imaging and labeling of biological systems. Strongly enhanced fluourescence from fluorophore, mediated by optical resonant field, is attributed to surface plasmon (SP) coupling between Ag NW and NDs. We succeeded in obtaining the fairly enhanced fluorescence intensity and quenched lifetime from LDS798 dye (1-Ethyl-4-(4-(p-Dimethylaminophenyl)-1,3-butadienyl)-quinolinium Perchlorate) dissolved in 0.2{\%} poly(vinyl) alcohole (PVA). This novel nanoengineered plasmonic platform opens up a new horizon for a more efficient and direct way to image a cell and biological system. [Preview Abstract] |
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FP1.00062: Evidence for hexagonal diamond in CVD grown diamond thin films Rajarshi Chakraborty, Suresh Sharma Hexagonal diamond, an energetically unfavorable carbon structure, has been of interest, since the first report of its synthesis from crystalline graphite at high pressure and temperature ($\ge $130 kbar and 1000$^{\circ}$C)......$^{1}$ The physical properties of this allotrope of carbon are significantly different from those of the cubic diamond. Although, the C-C bonding in both cubic and hexagonal structures is \textit{sp}$^{3},$ the stacking sequences are different. Whereas it is ``ABCABC{\ldots}'' in the commonly observed cubic structure, it is ``ABAB{\ldots}'' in hexagonal diamond. These structures are further characterized by: (i) bond length a = 1.545 {\AA} for cubic diamond and a = 2.52 {\AA} and c = 4.12 {\AA} for hexagonal diamond, (ii) calculated band gaps of 5.6 and 4.5 eV for the cubic and hexagonal structures, respectively, and (iii) relative stability (hexagonal being less stable), hardness (hexagonal is harder than cubic diamond), and different vibrational spectra.....$^{2}$ Based on the SEM and Raman spectroscopy data, we present clear evidence for nanometer size (10-100 nm) hexagonal diamond particles in CVD-grown diamond thin films....$^{3, 4}$ $^{1}$F. P. Bundy and J. S. Kasper, J. Chem. Phys. \textbf{46}, 3437 (1967) $^{2}$M. R. Salehpour and S. Satpathy, Phys. Rev. B \textbf{41}, 3048 (1990) $^{3}$S. C. Sharma et al, J. Mater. Res.\textbf{5}, 2424 (1990) [Preview Abstract] |
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FP1.00063: Electronic Structure of Bimetallic Core/Shell Quantum-Dots Ruben Estrada-Salas, Hector Barron, Devraj Sandhu, Miguel Jose-Yacaman A quantum-dot (QD) is a nanoscale structure consisting of one or more semiconducting materials in which the motion of fundamental charge carriers is confined in all spatial dimensions. Core/shell quantum-dots (CSQDs) are a variety of QD consisting of two sections: An ellipsoidal core is manufactured from one material, and a shell of a second material is added around this. QDs have been the subject of great scientific and technological interest, with promising applications that include display devices, biological tagging materials, photovoltaics, and lasers. In this work, the electronic structure of bimetallic CSQDs (size $<$ 2 nm) is analyzed by using Density-Functional Theory (DFT), with the end of correlate their electronic properties with their potential applications. We select the Au/Ag, Au/Pd and Au/Pt systems because of the experimental studies reported on these systems. [Preview Abstract] |
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FP1.00064: Synthesis and characterization of monodispersed icosahedral Au using spherical aberration correction J. Jesus Velazquez-Salazar, Rodrigo Esparza, Miguel Jose Yacaman Monodisperse icosahedral Au nanoparticles were synthesized using one step protocol. The morphology and structural characteristics of the icosahedral Au nanoparticles with uniform size were studied in detail using ultra-high resolution scanning electron microscope (SEM) FEG Hitachi S-5500 (0.4 nm at 30 kV) with BF/DF Duo-STEM detector, high resolution transmission electron microscope (HRTEM) Jeol JEM-2010F with an accelerating voltage of 200 kV (resolution 0.19 nm point-to-point) and a scanning transmission electron microscope Jeol JEM-ARM200F (STEM) attachment with a spherical aberration corrector. The average size of the icosahedral Au nanoparticles was 10 nm. STEM Cs-corrected images showed the atomic structure of the nanoparticles, oriented mainly on the five and two fold exes. The nanoparticles were also characterized using UV/vis absorption spectrum. [Preview Abstract] |
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FP1.00065: Microwave-assisted synthesis and characterization of star-shaped zinc oxide micro and nanostructures Flor Esthela Palomar Perez, Idalia Gomez de la Fuente, Miguel Yacaman This work reports the synthesis of star-shaped ZnO nanostructures from Zn(NO$_{3}$)$_{2}$ and methenamine by microwave assisted method. The molar ratio of the precursors and microwave power irradiation were the main parameters for the synthesis. XRD shows ZnO in wurtzite structure. SEM images show the presence of star-shaped zinc oxide structures from 300 nm to 3 $\mu $m which grew from nanorods. The methenamine proportion in the solution acts as director for the rods production. In the 1:1 molar ratio only star shaped zinc oxide nanostructures were obtained. [Preview Abstract] |
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FP1.00066: Possible mechanism(s) behind recently observed effects of incorporating gold nanoparticles into a polymer-dispersed liquid crystal Alfonso Hinojosa, Suresh Sharma Recently we reported that addition of relatively small concentrations of about 14-nm diameter gold nanoparticles (Au NPs) to a polymer-dispersed liquid crystal (PDLC) produces rather large changes in the electro-optical properties of the PDLC. For example, addition of Au NPs to PDLC microstructure lowers its threshold voltage by almost 50{\%} and increases optical transmission in a manner that depends on NPs concentration and applied electric field.\footnote{A. Hinojosa and S. C. Sharma, Applied Physics Letters, \textbf{97}, 081114 (2010)} In order to understand these observations, we have carried out electro-optical measurements on several PDLCs as functions of the polarization of the incident laser beam and applied electric field. In this presentation, we will discuss the results obtained from these experiments and suggest mechanism(s), which might explain NPs-induced changes in the electro-optical properties of PDLCs. [Preview Abstract] |
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FP1.00067: Piezolectric Charging for Smart Fabric Applications Ross Hackworth, Julie Moriera, Ramakrishna Kotha, Robert Maxwell, Arturo Ayon We report on the feasibility of employing flexible poly(vinylidene fluoride), or pvdf, piezoelectric membranes to be used to generate an electrical charge for powering portable electronics. By converting a person's naturally expended mechanical energy into useful electrical energy, the batteries currently in use in portable electronic devices may be minimized, as well as made efficiently green. Our current research includes an innovative design and fabrication method that integrates a flexible piezoelectric onto clothing similar to previous works, our approach is to build the devices directly onto the fabric allowing for low temperature processes (less than 200 \r{ }C). The device will consist of a bottom electrode/wearable fabric, a piezoelectric layer and a top electrode to complete the power generating smart fabric. A membrane 6 $\mu$m thick of PVDF is combined with 100 nm sputtered gold electrodes on the outer surfaces to allow for electrode contacts. The contacts are connected to a data collection device, a rechargeable battery, or a capacitor as required for energy storage and evaluation. The electrodes are connected to a DAC system to determine the voltage output. The membrane generates a voltage of approximately 200 mV, with a background noise level of 40 mV. [Preview Abstract] |
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FP1.00068: Acceleration of H$^{-}$ ions for the Cyclotron Institute Upgrade Project Juan Olvera, Henry Clark The Cyclotron Institute at Texas A{\&}M University is undergoing an upgrade that will allow for the production of radioactive ions for nuclear physics experiments. These ions will be produced with one of two ion guides, then collected, charge boosted and reaccelerated in the K500 cyclotron. The first radioactive ion beam for the project will be $^{27}$Si (T$_{1/2}$=4.16s) at 15 MeV/u and will be produced through the reaction $^{27}$Al(p,n)$^{27}$Si with 30 MeV protons. The recently recommissioned K150 cyclotron will accelerate the proton beams to intensity as high as 20 $\mu $A in order to produce sufficient amounts of radioactive ions. Rather than using an electrostatic deflector to extract the proton beam from the cyclotron, H$^{-}$ ions will be introduced into the cyclotron, accelerated to 30 MeV and then stripped to protons with a thin carbon foil at extraction. First tests show the extraction efficiency to be nearly 100{\%} and that the technique greatly reduces interior activation of the cyclotron and problems from secondary radiation. The H$^{-}$ ion source, injection scheme and results from first tests will be presented. [Preview Abstract] |
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FP1.00069: Experimental Verification of Moseley's Law and the Measurement of Environmental, Pollution, and Biological Samples using X-Ray Fluorescence analysis Venkata Kummari, Sahil Naik, Ritish Patnaik, Jerome Duggan, Bibhudutta Rout X-rays are in general known to follow Moseley's Law. He provided the first concrete experimental evidence in favor of Bohr's theory of the atom. His major discovery was that there is a systematic mathematical relationship between the X-ray produced by the target and the atomic number of the target. This relationship became known as Moseley's Law and just think he was only 25 years old when he made this discovery. Moseley's Law states that the frequency of the K$_{\alpha }$ radiation is given by: f$_{ K\alpha } \quad =\frac{3cR}{4}(Z-1)^{2}$ where c is the velocity of light and R is the Rydberg constant. Therefore a plot of the square root of frequency of the K$_{\alpha }$line versus the atomic number of the element should be a straight line. A similar plot for the K$_{\beta 1}$ line also yields a straight line. In this poster we will show the X-ray fluorescence measurement of a variety of environmental, pollution and biological samples. The X-rays from these samples were excited with an X-ray tube and radioactive sources which gives experimental verification of Moseley's Law and X-ray fluorescence measurement. [Preview Abstract] |
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FP1.00070: Constructing the Hodoscope Arrays for the Fermilab E-906/SeaQuest Spectrometer Brianna Edlund SeaQuest is a fixed-target experiment designed to extract the light antiquark sea structure of the proton at high Bjorken-x. Using 120 GeV/c protons from the Fermilab Main Injector, the experiment will measure the cross section ratio of di-muon pairs produced by the Drell-Yan process with liquid hydrogen and deuterium targets. From this ratio the light antiquark ratio will be extracted. The trigger for the di-muon pairs uses a set of 8 hodoscope planes, the final four of which are the topic of this work. The final four hodoscope planes consist of 128 scintillator paddles and 224 photomultiplier tubes (PMTs). Due to their size, three planes require PMTs on each scintillator end to avoid timing jitter. SeaQuest uses the old PMTs and tube bases from E866/NuSea, plus other experiments, so it was critical to verify the performance of each PMT and base. These tests included operating voltages, noise rates, and rate capability. The methods used will be presented as well as how the results were used to optimize efficiency in the spectrometer's expected high-rate regions. [Preview Abstract] |
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FP1.00071: Development of a Gas Stopper for Fusion-Evaporation Products Jordan Sefcik, Charles Folden III, Marisa Alfonso New plans are needed in order to chemically study superheavy elements. According to a design from Michigan State University, implementing a gas stopper is the best way to do this. After being transferred through a Momentum Achromat Recoil Separator (MARS), produced ions of $^{158}$Hf eventually reach a variable angle mylar degrader, Reaction Transfer Chamber (RTC) window, which is followed by a gas stopper of helium. Inside the gas cell is a series of electrodes, followed by a funneled ``flower petal'' design. Using the simulating program SIMION, the electrodes have electric potentials applied to each of them in order to funnel the ions into a small opening at the end of the gas stopper. Here the ions will undergo certain chemistry experiments in order to learn more about them. The hafnium ions enter the gas stopper with an energy of $\sim $3 MeV. However, when they reach the end of the cell, they must have an energy on the order of 0.1 eV in order perform certain chemistry experiments on them. Using an optimized set of potentials, the survival rate for the simulated ions was 96{\%}. These results are agreeable in the sense that within error bars, there is no room for improvement in extraction efficiency. This set-up also gives desirable results for $^{257}$Rf, which is considered a superheavy element and is thought to have the same periodicity as hafnium. [Preview Abstract] |
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FP1.00072: Upsilon + Hadron correlations at the Relativistic Heavy-Ion Collider (RHIC) Matthew Cervantes STAR has the capability to reconstruct the heavy quarkonium states of both the J/Psi and Upsilon particles produced by the collisions at the Relativistic Heavy Ion Collider (RHIC). The systematics of prompt production of heavy quarkonium is not fully described by current models, e.g. the Color Singlet Model (CSM) and the Color Octet Model (COM). Hadronic activity directly around the heavy quarkonium has been proposed [1] as an experimental observable to measure the radiation emitted off the colored heavy quark pair during production. Possible insight into the prompt production mechanism of heavy quarkonium can be obtained from this measured activity. Using STAR data from pp collisions at $\sqrt{s}$= 200 GeV, the high S/B ratio found in Upsilon reconstruction can enable us to perform an analysis of Upsilon + Hadron correlations. We will present our initial investigation of such an analysis.\\[4pt] [1] Kraan, A. C., arXiv:0807.3123. [Preview Abstract] |
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FP1.00073: Development of a Low-Level Counting Station Omar Magana A low-level counting station was developed to determine the half-life of $^{60}$Fe. The iron source was selected among other products during the process of nuclear collision. Utilizing a K1900 fragment separator from the NSCL facility at MSU, the $^{60}$Fe was produced and implanted into Al Foils. The iron was later extracted by a chemical process and precipitated nucleus as at the Argon National Laboratory. Since, the $^{60}$Co serves as a contaminant; the Cobalt was removed in chemistry, to insure all measure $^{60}$Co is from the decay of $^{60}$Fe. In order to achieve successful results, a low-level counting station was developed to maximize the background suppression using lead bricks. The lead castle was engineered to reduce background radiation that interferes with the detector. By doing so, various calibrations and arrangement of lead bricks were done to add suppression into the counting station. Once the detector shielding was ready, a background run was made in order to compare the difference between the previous shielding that was built last year by other colleagues. In future experiments, the $^{60}$Fe sample will be inserted into the detector. The $^{60}$Co activity will be measure to determine the half-life of $^{60}$Fe. [Preview Abstract] |
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FP1.00074: CdSe-ZnS Core-Shell and Gold Quantum Dots and the Effects of Different Substrates Gilbert Bustamante, Mohsen Purahmad, Rade Kuljic, Mitra Dutta Over the past 20 years, all areas of nanotechnology have been advancing, whether in basic understanding of their complexity or their use is various applications. Quantum dots, nanowires, and nanoparticles are just a few nanostructures used for a wide variety of applications, ranging from electronics, optoelectronics, to diverse biomedical uses. Due to the size of these particles and devices scaling down, we can no longer use classical physics to determine their behavior rather we need to use quantum mechanics. The goal now is to understand these nanostructures in order to use them effectively. Our objective for this project was to view the properties and formations of the layer of Cadmium Selenide, Zinc Sulfide (CdSe-ZnS) core-shell quantum dots when placed on different substrates, Glass, Indium Tin Oxide (ITO), Silicon (Si), and Gallium Arsenide (GaAs) and how Gold quantum dots reacted to substrates at different temperature differences. The CdSe-ZnS quantum dots were prepared in water then dropped cast onto each of the four substrates. Once the solution evaporated, we used Photoluminescence and UV-Vis Absorption Spectroscopy, along with viewing the substrates under a microscope, to investigate if the properties of the quantum dots were different and if the quantum dots formed any particular patterns. The results of the measurements show that the substrates have no significant effects on the quantum dots' properties but the formation of the quantum dots were different. [Preview Abstract] |
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FP1.00075: Exploration of Traveling Waves in High Field Magnetic Resonance Imaging Zachary Hernandez MRI has been a remarkable means of medical imaging for the last three decades without exposure to ionizing radiation. The increase in MRI signal with the increase of magnetic field strength is the main motive in a move towards imaging at higher field strengths. However, the advent of higher field strength MRI has come with the challenge of maintaining homogeneous excitation fields (B1). One promising solution to this has been to transmit radio-frequency (RF) signals using a patch antenna instead of the usual RF coil. This technique exploits the theory of waveguides and traveling waves typically used in high frequency applications. In this particular study we have investigated this unique application by measuring B1 maps, geometric distortions, and signal-to-noise ratios (SNRs) in order to better quantify its potential in MRI. Using phantoms to match the similar physical features of the human head/torso region, we ran comparative scans using the traveling wave setup versus the conventional head volume coil setup on a Philips 7 Tesla MRI scanner. The goal of this experiment was to systematically measure B1 maps for flip angle efficiency and multi-planar rendering images for geometric distortion. Although the application of traveling wave in MRI does suffer from low excitation (small flip angles), there seems to be little to no correlation between traveling wave phase variability and frequency/phase encoding. Therefore, further experiments, if carried out, may enhance image quality such as RF shielding, the use of local receive coils, and/or the addition of a second patch antenna. [Preview Abstract] |
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FP1.00076: Nanostructures: Temperature Dependence of Optical Properties for Solar Applications Alvaro Aguilar Within solar cell technologies, thin-film cells have been proven to provide up to 20{\%} efficiency in the laboratory. Our research group focused on Cadmium Telluride thin-film cells for two reasons: it can be readily synthesized as nano particles and it is known to make efficient thin-film cells. The optical characteristics of the CdTe layer of the cell were investigated with relation to temperature using the HORIBA Jobin Yvon Variable Angle Spectroscopic Ellipsometer and the LinkAM TMS94 Temperature Controller. Our results show that sintering nano particles of CdTe decreases the film's thickness and shifts the Energy Gap toward lower energies. The method used can be applied to different nano structures and even new materials. [Preview Abstract] |
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