Bulletin of the American Physical Society
2006 Texas Section of the APS Joint Fall Meeting
Thursday–Saturday, October 5–7, 2006; Arlington, Texas
Session P1: Posters and Coffee Break |
Hide Abstracts |
Chair: Robert Ramsey, Pete Williams, Marcus Hawkins, Heather Brown, University of Texas at Arlington Room: UT Arlington, University Center Rio Grande, 3:30pm-5:30pm |
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P1.00001: Photo and Thermo Responsive Poly-N-isopropylacrylamide Gel J'Nae Zwaschka, Tong Cai, Antonio Garcia, Manuel Marquez, Devens Gust, Sean Vail, Zhibing Hu Hydrogels composed with poly (N-isopropylacrylamide)-co-Spiropyran acrylamide (PNIPAM-co-SP) were studied for their photo and thermal responsive properties. A mixture of a certain amount of N-isopropylacrylamide monomers, spiropyran acrylamide, crosslinker N, N$'$-methylene-bis-acrylamide, and photo initiator in acetone/ water solvent was irradiated by UV light to synthesize this PNIPAM-co-SP hydrogel. PNIPAM-co-SP hydrogel was then balanced in water for two days and its property measured by using UV-visible spectroscopy. It is found that the gel's size and charge may be altered using stimuli including light of different wavelengths and temperature. [Preview Abstract] |
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P1.00002: Supergranules -- The True Nature of Solar Rossby Hills? Peter Williams, Manfred Cuntz, David Hathaway Supergranulation is a well established component of solar convection and visible on the solar surface as cellular structures. The convective upflow within a supergranule cell overshoots the equilibrium solar surface creating a corrugated surface. The hills associated with these upflows have been detected as they pass over the solar limb. Their discovery was initially attributed to Rossby waves, arising from r-mode oscillations in the Sun where the Coriolis force acts as a restoring force on internal gravity waves. We analyze these hills by producing an artificial height map derived from the radial component of supergranule Doppler velocity data constructed from the spectral components of a synthetic photospheric convection spectrum. We are able to show that the observed signals leading to the detection of these solar hills can be modeled by applying the same methods that lead to the Rossby wave `discovery', prompting the conclusion that the corrugation has its origins in supergranulation. [Preview Abstract] |
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P1.00003: Spectroscopic Study of Nuclear Processing in the Crab Nebula Gordon MacAlpine, Tait Ecklund, William Lester, Steven Vanderveer We present correlations for optical and near-infrared line intensity measurements at many positions in the Crab Nebula supernova remnant. These correlations suggest the existence of gas produced by a range of nuclear processing, from material in which synthesis ended with the CNO-cycle, to some helium-burning and nitrogen depletion, to regions containing enriched products of oxygen-burning. The latter exhibit a gradual, linear rise of [Ni II] emission with increasing argon enrichment, whereas gas with less nuclear processing shows markedly different [Ni II] emission characteristics, including the highest derived abundances. This suggests two origins for stable, neutron-rich nickel in the nebula: a type of ``alpha-rich freezeout'' in the most highly processed material, and perhaps removal of ions from the neutron star in other regions. In addition, the data indicate that anomalously strong observed [C I] emission comes from extensive, warm, low-ionization zones. Although the strongest He I emission could also be enhanced in similar low-ionization gas, correlations between relevant line ratios argue against that explanation, strengthening the case for an exceptionally high helium mass fraction in some locations. [Preview Abstract] |
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P1.00004: Primordial Black Holes and Structure Formation Adam Drake Primordial Black Holes (PBHs) were first proposed by Zel`dovich \& Novikov (1967) and Hawking (1971) as a consequence of the extremely high densities that occur in the Big Bang model. They differ from other black holes in our universe in that they do not have stellar progenitors and have a wide range of possible masses $M_{\rm PBH} \sim 10^{-5}g$ and $M_{\rm PBH} \ge 10^{15}g$. It is well-established that supermassive black holes (SMBHs) with masses in the range of $10^6 - 10^{9.5}M_{\odot}$ reside in most galactic centers. These SMBHs have grown largely through accretion but it is still unclear how they formed. We examine the possibility that PBHs are the seeds from which SMBHs grow and attempt to determine the viability of PBHs as a dark matter candidate. [Preview Abstract] |
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P1.00005: Case Studies of the Restricted Three Body Problem Jason Eberle, Manfred Cuntz, Zdzislaw Musielak Are we alone in the universe? Nobody can give an answer yet. However, one step on the way to find out is to inquire how many planets in the universe could harbor life. An important feature a planet should have for life to exist is that the planet shouldn't crash into the star or fly off into interstellar space. In regard to our own solar system this is a non-issue as all planets are known to have orbited the Sun for billons of years. The unfortunate truth is that most planets don't have it as nice as Earth does. In fact, about half of all known stellar systems harbor two or more stars, thus affecting orbital stability of any planets in the systems. It is found that when a system harbors two stars, the planet may orbit one or both stars, depending on the physical conditions, or may even be kicked out of the neighborhood of the stars completely, and lost in space forever. In this poster, we provide detailed case studies for planets in binary systems. [Preview Abstract] |
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P1.00006: THz Time-Domain Spectroscopy of D2O Jenelyn Ramos, Jojit Torcedo, Harry Tom To better understand the properties of water, the dielectric spectrum of water is measured using Terahertz Time-Domain Spectroscopy where data is collected between 20 GHz to 2 THz. We use the reduced polarization formula to obtain the microscopic dipole correlation function from the macroscopic dielectric function. The microscopic dipole correlation function is fit by 2 Debye relaxations and nine Lorentzians where four of the Lorentzians are known and the five remaining are of both positive and negative amplitude which is the first evidence of anticorrelated effects of bulk water. The data of water at 4 $^{\circ}$C shows an extra tenth low frequency oscillation at 21 GHz that isn’t found at 0.5 or 8 $^{\circ}$C. This feature is significantly larger in amplitude than the others. The appearance and disappearance of a new peak at 21 GHz may be fundamentally related to the density anomaly of water. We test this possibility by searching for a similar anomalous feature in D2O around its 11.2 $^{\circ}$C density anomaly. [Preview Abstract] |
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P1.00007: A Compact Detection System for High Sensitivity Hydrogen Profiling of Materials by Nuclear Reaction Analysis Jose Pacheco, Ben Urban, Daniel Marble Hydrogen is a ubiquitous contaminant that is known to have dramatic effects on the electrical, chemical, and mechanical properties of many types of materials in even minute quantities. Thus, the detection of hydrogen in materials is of major importance. Nuclear reaction analysis (NRA) is an ion beam technique capable of non-destructively profiling hydrogen in a wide range of materials from semiconductors to metals with high depth resolution (5 to 10 nm). It can also be used to standardize other techniques like SIMS. However, traditional NRA has found only limited application in the semiconductor industry even to quantify SIMS because of poor sensitivity due to cosmic ray background. Most attempts to eliminate this background to achieve ppm detection levels using higher energy nuclear reactions or tons of passive shielding are not compatible with commercial ion beam analysis space and equipment requirements. We have developed an NRA coincidence detection system that eliminates CSRB and offers state-of-the-art hydrogen detection capability while being compatible with existing IBA space and hardware requirements. A discussion of the detector system, its' design, and our background and efficiency measurements will be presented. [Preview Abstract] |
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P1.00008: Structure Refinement of a Sol-gel Derived Pyrochlore Bi$_{2}$Ti$_{2}$O$_{7}$ Using a Neutron Scatterings Won-Jeong Kim, Sang Su Kim, Jong Kuk Kim, Jun Ki Chung, Mun Heum Park, Tae Gon Ha, Eun Jin Choi, Jin Won Kim, Hyun Kyeong Cho Structure of the sol-gel derived pyrochlore Bi$_{2}$Ti$_{2}$O$_{7}$ has been refined by a Rietveld analysis method using neutron and x-ray scattering data. The structure of Bi2Ti2O7 was assumed as Fd-3m (space group number 227). The calculated lattice constant was 10.3735(3) nm. The sample contains a majority Bi$_{2}$Ti$_{2}$O$_{7}$ phase and minor Bi$_{4}$Ti$_{3}$O$_{12}$, Bi$_{12}$TiO$_{20}$, and TiO$_{2}$ phases. After subtracting the secondary phases effect, the total goodness of fit using both scatterings was conversed to $\chi ^{2}$ = 2.6, Rp = 6.5 {\%}, and wRp = 8.6 {\%}, which suggesting that the refined structure of Bi$_{2}$Ti$_{2}$O$_{7}$ is reasonable. Bi atom occupies 96 g site with probability of 0.158(1), while O occupies 8 a site by 0.884(16). Furthermore, Bi$_{2}$Ti$_{2}$O$_{7}$ thin film has been fabricated by a sol-gel method. After depositing electrodes, electrical properties of the thin film have been measured. Interestingly, a ferroelectric characteristics has been observed; electric field dependent dielectric constant. The refined structure information of Bi$_{2}$Ti$_{2}$O$_{7}$ may explain the observed ferroelectricity of the thin films. Details of the structural and electrical properties of Bi$_{2}$Ti$_{2}$O$_{7}$ will be discussed. [Preview Abstract] |
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P1.00009: Observation of the high sensitivity of Positron Annihilation induced Auger electron spectroscopy to thermally induced changes in the oxidation state of Cu atoms at the surface of previously oxidized Cu(100) M.P. Nadesalingam, S. Mukherjee, N. Fazleev, B.R. Davis, J. Zhu, A.H. Weiss Changes in the surface of an oxidized Cu(100) single crystal resulting from vacuum annealing over a temperature range from 20 $^{\circ}$C to 800 $^{\circ}$C has been investigated using Positron annihilation induced Auger electron spectroscopy (PAES). The PAES measurements show a large monotonic increase in the intensity of the annihilation induced Cu (M$_{2,3 }$VV) Auger peak as the sample is subjected to a series of isochronal anneals in vacuum up to annealing temperature 300 $^{\circ}$C. The intensity then decreases monotonically as the annealing temperature is increase to $\sim $600 $^{\circ}$C. The Ps fraction, f$_{PS}$ of these surfaces was found to have the opposite trend going from f$_{PS}$ = 0.79 for the surface before any annealing to f$_{PS}$ =0.51 after annealing at 300 $^{\circ}$C. These results provide a clear demonstration of the thermal reduction of the copper oxide surface after annealing at 300 $^{\circ}$C followed by re-oxidation of the copper surface at the higher annealing temperatures presumably due to the diffusion of subsurface oxygen to the surface. [Preview Abstract] |
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P1.00010: The effects of vacuum annealing on the surface of 6H- SiC studied using Positron Annihilation induced Auger Electron Spectroscopy Saurabh Mukherjee, Manori Nadesalingam, Brian Davis, Gerhard Brauer, Alexander Weiss The effects of vacuum annealing on the surface of 6H- SiC surface has been studied by Time of Flight --Positron Annihilation induced Auger Electron Spectroscopy (TOF-PAES). Meas urements were performed using a time of flight PAES spectrometer that was capable of moni toring the top layer surface concentrations of C, O and Si. The results indicate that the SiC surface was initially covered with a layer containing oxygen but largely devoid of Si which was subsequently removed as a result of vacuum annealing to expose Si and C in the top layer. The study was the first application of a TOF-PAES spectrometer to the SiC surface and clearly demonstrated the utility of PAES in the study of the surface modification of SiC. [Preview Abstract] |
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P1.00011: FTIR investigation into Degradation of Natural Rubber Ryan Rich, T. Waldek Zerda The aging of tires is of the highest concerns to the automotive industry, due to its implications in fuel economy and automobile safety. Previously, the high absorption rate of carbon black filled polymers has hindered the use of Fourier Transform Infrared Spectroscopy (FTIR) in studying this occurrence. However, recent developments in attenuated total reflection (ATR) techniques have provided a means for spectroscopically monitoring the composition changes induced in rubber blends by heat, exposure to ultra-violet radiation, and mechanical strain. The ATR apparatus, employing a germanium crystal, collected high quality infrared spectra at a reduced penetration depth of less than one micron. This research analyzed natural polymer blends with varied aggregate size and concentration of carbon black. The samples were analyzed as a function of exposure time to 70\r{ }C heat and UV radiation, as well elongation by mechanical strain. In these spectra, growth of the 1740cm$^{-1}$ peak is assigned to increase populations of the C=O band. Carbon black filler rubber is shown to slow the rate of oxidation in pure natural rubber. Crystallization of rubber composites under strain is characterized by changes in the shapes of the CH stretch bands. [Preview Abstract] |
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P1.00012: FTIR Studies on Cyclic ($c$-C$_{n}$, $n \le $ 8) and Linear ($\ell $-C$_{n}$, n $\ge $ 7) Carbon Clusters Rafael Cardenas, C.M.L. Rittby, W.R.M. Graham Carbon clusters are formed in the laboratory by trapping the products from the Nd-YAG laser evaporation of graphite in argon and neon matrices. Linear and cyclic C$_{n}$ have been the subjects of extensive theoretical and experimental studies for many years and are important in several areas. Carbon chains are backbones for many molecules detected in the interstellar and circumstellar media. Carbon clusters are important in fullerene chemistry and fuel combustion. FTIR measurements of vibrational fundamentals and carbon-13 isotopic shifts, coupled with the predictions of theoretical calculations, have been successfully employed to identify and characterize the vibrational spectra of a variety of cyclic and linear chains of carbon atoms. For longer C$_{n}$ ($n \ge $ 6) chains, identifications are made easier if both the isotopic pattern for single $^{13}$C-substituted $^{12}$C$^{13}$C$_{n-1}$ isotopomers and the ``mirror'' isotopic pattern for single $^{12}$C-substituted $^{13}$C$^{12}$C$_{n-1}$ isotopomers can be observed. Once we established a process to produce highly enriched carbon rods ($\sim $85{\%},$^{13}$C), well-resolved isotopic spectra for cyclic $^{13}$C$_{n}$ ($n $=6,8) and linear $^{13}$C$_{n}$ carbon clusters ($n $=3-12) are now obtained routinely. Recent results for cyclic C$_{8}$, linear C$_{7}$, and longer linear C$_{n}$ ($n \ge $ 10) chains are discussed. [Preview Abstract] |
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P1.00013: FTIR Isotopic Study of the $\nu_1$($\sigma$) Stretching Mode of Linear CrC$_3$ Condensed in Solid Ar S.A. Bates, C.M.L. Rittby, W.R.M. Graham Earlier gas phase investigations of chromium-carbon species using photoelectron spectroscopy (PES) and density functional theory (DFT) calculations have shown the existence of both the \textit{C}$_{2v}$ (fan-shaped) and linear isomers of CrC$_3 $.\footnote{H.~-J.~Zhai, L.~-S.~Wang, P.~Jena, G.~L.~ Gustev, and C.~W.~Bauschlicher, Jr., \textit{J. Chem. Phys.} \underline {\textbf{120}}, 8996 (2004).} We report the first results from Fourier transform infrared (FTIR) spectroscopic studies on CrC$_3 $, produced by Nd:YAG laser ablation of carbon and chromium rods and trapping the products in solid Ar at $\sim$10 K.\footnote {S.~A.~Bates, C.~M.~L.~Rittby, and W.~R.~M.~Graham, \textit{J. Chem. Phys.} \underline{\textbf{125}}, 074506 (2006).} Extensive $^{13}$C isotopic shift measurements and predictions from DFT calculations at the B3LYP/6-311G+(3\textit{df}) level show that linear CrC$_3$ is the ground state isomer and enables the assignment of its $\nu_1$($\sigma$) fundamental at 1789.5 cm$^{- 1}$. [Preview Abstract] |
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P1.00014: Raman Mapping of Stress Distribution in Diamond Composites M. Wieligor, T.W. Zerda Mapping of residual stress in diamond-SiC composites, sintered by liquid silicon infiltration, was obtained by analyzing splitting of Raman peak of diamond. Under biaxial strain this peak splits and its components shift toward higher (compressive) or lower frequencies (tensile strain). The magnitudes of the shifts can be used to estimate residual stress. Using a confocal Raman microscope we obtained spectra from areas less than 1 micron in diameter and thus acquired information on stress distribution within diamond crystals. Only shifts corresponding to compressive strains were detected. For the samples sintered at 10 GPa stress increased with increasing sintering temperature reaching a maximum value of 3.2 GPa. Largest concentrations of strains were found on diamond surfaces in direct contact with other diamonds. We explain these results in terms of different thermal expansion coefficients of silicon and diamond phases. Although during the early stages of the infiltration diamonds were under hydrostatic conditions, later after SiC was formed and the system cooled down, due to different thermal expansion coefficients SiC contracted more than diamond and thus exerted compressive forces. [Preview Abstract] |
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P1.00015: FTIR Matrix Study of Transition-Metal Carbon Clusters and Potential Circumstellar Molecules: TiC$_{3}$ R.E. Kinzer, Jr., C.M.L. Rittby, W.R.M. Graham Results will be presented of recently initiated studies on the structures and infrared spectra of transition metal-carbon clusters that may be of interest in circumstellar shells or other astrophysical environments. Such clusters are also of interest as fundamental building blocks for larger metal-carbon structures, such as metallocarbohedrenes. The FTIR (Fourier transform infrared) spectrum of TiC$_{3}$ was observed by trapping the vapors produced during dual Nd:YAG laser ablation of Ti and C rods in solid Ar at $\sim $10 K. Measurements of frequencies and $^{13}$C isotopic shifts have enabled the identification of the fan-like ($C_{2v})$ isomer of TiC$_{3}$ with vibrational fundamentals \textit{$\nu $}$_{3}(a_{1})$ = 624.3 and \textit{$\nu $}$_{5}(b_{2})$ = 1484.2 cm$^{-1}$. The results are in good agreement with the predictions of DFT calculations at the B3LYP/6-311G(3\textit{df}, 3\textit{pd}) level. The observed $C_{2v}$ structure is also consistent with the results from an earlier photoelectron spectroscopy study. [Preview Abstract] |
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P1.00016: Electric-pulse-induced resistive memory effect of PZT buffered perovskite thin film Zhongwen Xing, Naijuan Wu, Alex Ignatiev A large electric-pulse-induced resistance (EPIR) switching effect has been observed in the lead zirconate titanate (PZT) buffered perovskite thin films, such as Pr$_{0.7}$Ca$_{0.3}$MnO$_{3 }$(PCMO). Such a resistive memory device is comprised of a PCMO epitaxial layer on a c-oriented YBCO bottom electrode layer and a thin PZT buffer layer grown on top of the PCMO layer. A silver top electrode was deposited on the PZT/PCMO/YBCO heterostructure to complete the resistive device fabrication. There are two advantages for the memory properties comparing the PZT buffered device with a non-buffered thin film device. First, the EPIR resistance ratio [defined as (R$_{max}$-R$_{Min})$/ R$_{Min}$] is significantly increased. The other is that the pulse voltage needed to switch the resistive device is reduced from $\pm $10 V to $\pm $3 V in magnitude. These results suggest that PZT-buffered perovskite thin film resistive devices are very promising for memory applications. In addition, an effective tunneling model is developed to explain the EPIR effect. It is found that the tunneling at interfaces plays an important role in the charge transport, which is in good agreement with existing experiments. [Preview Abstract] |
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P1.00017: X-ray Diffraction and Polarized X-ray Absorption Study of Single Crystal LiFePO$_{4}$ Gan Liang, Ron Benson, Jiying Li, David Vaknin, Mark Croft Large size LiFePO$_{4}$ single crystals have been grown by standard flux growth technique with the LiCl as the flux. Single crystal x-ray diffraction (XRD) and synchrotron polarized x-ray absorption spectroscopy (XAS) measurements have been performed on the crystals. The XRD measurements were performed at T = 293 K using Mo $K_{\alpha }$ radiation ($\lambda $ = 0.7107{\AA}) to a resolution corresponding to sin$\theta $/$\lambda $ = 0.6486 {\AA}$^{-1}$, with 2$\theta _{max}$ = 54.9\r{ }. A total number of 1330 reflections were processed with 350 unique data. The obtained crystal structure data were the following: lithium iron (II) phosphate, LiFePO$_{4}$, orthorhombic, space group \textit{Pnma}, lattice constants: $a$ = 10.3172 (11) {\AA}, $b$ = 6.0096(8) {\AA}, $c$ = 4.6775 (4) {\AA}, Z = 4, formula weight: 157.76, density: 3.613, $\mu $ = 55.562 cm$^{-1}$. The bond lengths between Fe and O and between P and O were obtained. The polarized XAS was performed at the Fe $K$-edge with the x-ray \textbf{E}-vector along the a-, b-, and c-axis. The XAS results show that the Fe ions in the LiFePO$_{4}$ single crystals are divalent. We also observed a big shift in both the energies of the pre-edge 1$s \quad \to $ 3$d$ transition feature and the main edge when the polarization direction of the \textbf{\textit{E}}-vector changes from along $a$-axis to along $c$-axis. [Preview Abstract] |
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P1.00018: 10 MeV Electron Beam Test Using Gas Electron Multiplier (GEM) Detectors C.H. Hahn, I.G. Kim, S.T. Park, W.J. Kim, D.S. Yoo, B.S. Moon, S.Y. Ha, B.J. Ahn, Y.J. Ha, C.Y. Jung, S.H. Jung, B.H. Cho, B.C. Lee, Y.H. Han, C.E. Chung, J. Li, A.P. White, J. Yu 10 MeV electron beam has been tested using a single channel double gas electron multiplier (GEM) detector constructed by Changwon National University and a multi-channel double GEM chamber by the University of Texas at Arlington. It has been demonstrated that both detectors are able to detect signals generated by high energy electrons as well as x-rays. By analyzing the chamber output signals captured by oscilloscope, it is believed that the x-ray was produced by bremsstrahlung while electrons were decelerating in a 2 mm lead plate. The time profile of the KAERI's 10 MeV electron beam bunches was determined based on the calculated angular distribution of electrons by multiple scattering in the lead plate. Furthermore, the spatial electron density distribution has been extrapolated by using the time profile. The effective gain of the GEM chamber has been estimated by analyzing the measured output currents of the chamber. It is important that the time and spatial profiles of the high energy electron beam could be determined using GEM detectors, which suggests that GEM might have an application as a calorimeter for a large scale accelerator. Details of experimental procedure will be discussed. [Preview Abstract] |
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P1.00019: An Ultra-fast Time-of-flight Counter Pedro Duarte, Andrew Brandt Preliminary studies of a fast time-of-flight counter will be presented. This counter makes use of the Cerenkov effect to provide precise timing with a goal of 30 psec resolution. [Preview Abstract] |
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P1.00020: A Study of the Impact of the GEM Foil Leakage Current to Gains Heather Brown, Changhie Hahn, Wonjeong Kim, Jia Li, Carlos Medina, Akihiro Nozawa, Jacob Smith, Andy White, Jaehoon Yu Many factors affect the amplification factor or gain and performance of the GEM chambers. GEM foil is one of the core component technologies of the conceptual digital hadronic calorimeter (DHCal). The GEM chamber amplifies electric signal from traversing charged particles using high electric field applied across the foil and a mixture of gas as the medium to provide ionization electrons. This study focuses specifically on the reduction in gain of the chamber due to the leakage current in GEM foils under the high voltage, since understanding the relationship between these two parameters is essential for optimal performance of the chamber. We will be highlighting the chain of relationships leading to the final correlation between leakage current and the gain. Ultimately, we present what the impact of a few nano-amperes of leakage current to the total gain of the GEM chamber. We will present how the findings from this study results in improvement of the chamber design. [Preview Abstract] |
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P1.00021: UTA Large Cloud Chamber Research Project Kenneth Crawford, Jacob Smith, James Creel, Shane Spivey, Priya Mydur, Pedro Duarte, Jay Purhee, Carlos Medina, Randi Gbur, Heather Brown, Jaehoon Yu A cloud chamber is a particle detector that shows the traces of charged particles using super-cooled vapor. The UTA Large Cloud Chamber group and the UTA SPS have jointly submitted a proposal to construct a $1m\times 2m\times 30cm$ cloud chamber which will be in display next to the newly constructed planetarium. The chamber will not only be used for K -- 12 education for demonstrating the existence of cosmic particles but also be used in higher level classes experiments, such as cosmic ray angular distributions. In this talk, we present the research done for the design of the UTA large cloud chamber. We will present the improvements in technologies of the detector parts and the optimal design considerations, along with our plans with the final design. [Preview Abstract] |
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P1.00022: Dependence of isoscaling on the nuclear equations of state R. Gamboa, C.O. Dorso, C.R. Escudero, J.A. Lopez The dependence of nuclear isoscaling on the stiffness of the equation of state (EOS) was studied using molecular dynamics simulations.~ Reactions of ${ }^{40}Ca+{ }^{40}Ca$,${ }^{48}Ca+{ }^{48}Ca$~and ${ }^{52}Ca+{ }^{52}Ca$~at beam energies ranging from 20 MeV/A to 85 MeV/A were simulated using the Pandharipande EOS of 535 MeV and compared to previous results obtained with the EOS of 250 MeV. ~The analysis included a study of the time evolution of this effect and the estimation of the isoscaling parameters $\alpha ,\beta $. ~Preliminary results indicate that isoscaling exists at all energies and at all times starting from the early primary isotope distributions all the way to 5000${fm} \mathord{\left/ {\vphantom {{fm} c}} \right. \kern-\nulldelimiterspace} c$. ~The $\alpha ,\beta $~were found to vary substantially from values obtained with the soft EOS. [Preview Abstract] |
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P1.00023: Determination of Acceptance for the $\pi^{-}$ p -$>$ ${\rm K}\Lambda$ Reaction Dolapo Soboyede ACU fairly recently became involved in an experiment proposed by the Institute for Theoretical and Experimental Physics (ITEP) and the Petersburg Nuclear Physics Institute (PNPI). In this experiment, our aim is to gain a better understanding of the second and third resonance regions in pion-nucleon scattering. In $\pi ^{-}$ p -$> \quad \pi ^{-}$ p scattering, the P$_{11}$ (1710) resonance is poorly seen, but in the $\pi ^{-}$ p -$>$ ${\rm K}\Lambda $ reaction the resonance is more clearly defined. In addition, previous experiments have been insensitive to narrow pion-nucleon resonances, but this experiment will be sensitive to such excited states of bound quarks. This research focuses on a GEANT4 simulation of the experiment and an analysis of the data using ROOT in order to determine the acceptance for the $\pi ^{-}$ p -$> \quad {\rm K}\Lambda $ reaction. Our experimental setup is designed to detect only charged particles, thus this research concentrates on charged decay modes. [Preview Abstract] |
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P1.00024: Properties of SmCo nanoparticles prepared by surfactant-assisted ball milling Yiping Wang, Yang Li, Chuanbing Rong, J. Ping Liu SmCo series nanoparticles were successfully prepared by surfactant-assisted ball milling process. After ball milling with surfactant, these nanoparticles were nicely dispersed in the solution. The phases of these nanoparticles were determined by XRD. By controlling the settling down time, SmCo nanoparticles with different sizes could be obtained. The magnetization measurement shows that the magnetic properties of SmCo nanoparticles intensively depend on the particle size. The larger nanoparticles present a good coercivity of 5 kOe, however, these small size nanoparticles of about 7nm only show a coercivity of several tens Oersteds. [Preview Abstract] |
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P1.00025: Synthesis and properties of bimagnetic core-shell nanoparticles Vikas Nandwana, Girija Chaubey, Kazuaki Yano, Ping Liu Bimagnetic core-shell nanoparticles are synthesized from high-temperature solution phase coating of FePt core with tunable Fe$_{3}$O$_{4, }$CoFe$_{2}$O$_{4}$ or FeCo shell. Magnetic properties of the as-synthesized core-shell particles are dependent on shell material and its thickness due to the exchange coupling between core and shell. Upon reductive annealing, an assembly of the core/shell nanoparticles is transformed into a hard magnetic nanocomposite with enhanced energy product which is 30{\%} higher than single FePt phase. With proper choice of materials and dimension tuning of both core and shell, these core-shell nanoparticles may be used as building blocks for creation of novel functional nanomaterials for various magnetic applications. [Preview Abstract] |
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P1.00026: High density FePt-based nanocomposite bulk magnets prepared by warm compaction Chuan-bing Rong, Vikas Nandwana, Narayan Poudyal, J. Ping Liu, Mikhail E. Kozlov, Ray H. Baughman, Yong Ding, Zhonglin Wang Bulk FePt/Fe$_{3}$Pt nanocomposite magnets have been prepared by high-pressure warm compaction of chemically synthesized nanoparticles. Density of the bulk samples up to 95{\%} theoretical value has been obtained while the nanostructured morphology is retained. The grain size and size distribution of the bulk samples are quite small compared to those for materials fabricated by traditional techniques. It is found that the density is a function of the compaction pressure and temperature and is also strongly affected by the phase transition of the FePt compound from face-centered cubic structure to face-centered tetragonal structure. The compaction leads to strong interparticle exchange coupling in the compacts. Post-annealing of the compacts results in improved interface condition and a further enhancement of magnetic performance. Energy products up to 16.3 MGOe of the isotropic bulk nanocomposite magnets have been achieved. [Preview Abstract] |
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P1.00027: Novel Approaches for the Synthesis of FeCo Nanoparticles Narayan Poudyal, Girija S. Chaubey, Chuanbing Rong, J. Ping Liu FeCo alloys are an important soft magnetic material because of their unique magnetic properties including large permeability and very high saturation magnetization. FeCo nanoparticles have attracted great interests recently because of their potential applications as building blocks of advanced nanomagnets and applications in biomedical technologies. However, preparation of monodisperse FeCo nanoparticles remains a challenge due to the poor chemical stability of the nanoparticles. In this poster, we report two novel routes of preparation of monodisperse FeCo nanoparticles with controllable particle size and size distribution. First method involves the synthesis of FeCo nanoparticles by high temperature solution phase method. In our second approach, FeCo nanoparticles were prepared by salt matrix annealing of the CoFe$_{2}$O$_{4}$ nanoparticles in forming gas (7{\%} H$_{2}$ + 93{\%} Ar). The formation of the alloy nanoparticles were confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM).It is also found that the bcc FeCo nanoparticles are stable under ambient condition. The magnetization of the FeCo nanoparticles is found to be size dependent. [Preview Abstract] |
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P1.00028: The Field Emission Properties of Gallium Nitride Nanoribbons Morgan Lynch, Yudong Mo, Jose Perez The study of field emission (FE) properties of many nanostructures has been of importance lately in the fields of applied physics as an electron source. We focused on a sample of GaN Nanoribbons deposited on a silicon substrate. Using Ultrahigh Vacuum (UHV) techniques (on the order of a nanotorr), we study the FE properties of our GaN with a Piezotube (PZ). Fitted with a platinum tip, our PZ is moved within a distance on the order of a micron from the sample. At such a distance, we apply a voltage (typically between 60V -- 600V) across the vacuum, effectively shrinking the potential barrier to a value that allows the surface electrons to ``tunnel'' out. These electrons are registered as a current that varies from a picoamp to a microamp exponentially. After obtaining a reasonable plot of our data, we compare it to that predicted by the Fowler-Nordheim equation. We studied the effects of Residual Gas Exposure on the FE of our sample. We used such gases as O2, CO2, H2O vapor, and N2. We also studied the effects of Cesiating our GaN sample. In addition to FE, we also studied the GaN sample using Raman Spectroscopy and Atomic Force Microscopy (AFM) techniques to better characterize our sample. [Preview Abstract] |
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P1.00029: Influence of sintering temperature on the microstructure of diamond-SiC nanocomposites Levente Balogh, Stephen Nauyoks, Waldek Zerda Composites with nanosize diamond crystals and nanosize SiC matrix are obtained by sintering ultrasonically mixed nano-diamond and nano-Si powder at 8 GPa and temperatures between 1820 and 2320 $^{\circ}$C. The eCMWP (Extended Convolutional Multiple Whole Profile) fitting method is applied to the X-ray diffractograms of the sintered samples to determine the parameters of the microstructure. Crystallite size distribution, dislocation and twin density are determined and discussed. As sintering temperature increases crystallite size increases and defect densities decrease slightly in both phases. At sintering temperatures higher than 2000 $^{\circ}$C the microstructure of SiC shows a substantial change compared to lower sintering temperatures, crystallite size increases, dislocation and twin density decreases dramatically. Porosity measurements are also performed in order to see the relationship of these measured results with the microstructure of composites. [Preview Abstract] |
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P1.00030: Dislocations and Planar Defects in Silicon Carbide after High Pressure and High Temperature Sintering Stephen Nauyoks, Levente Balogh, Jeno Gubicza, Waldek Zerda Nanocrystalline SiC powder is sintered at temperatures of 1400, 1600, and 1800\r{ }$^{ }$C and pressures of 2, 4, and 5.5 GPa. The microstructure of the sintered SiC is studied with X-ray diffraction line profile analysis. After sintering there is an increase in the average SiC crystallite size indicating a coalescence of the powder particles. Stacking faults are the main lattice defect in sintered SiC with a smaller crystallite size, less then 20 nm, while dislocations are the main defect in sintered SiC with larger crystallite sizes. For the sample sintered at 8 GPa and 1800\r{ }$^{ }$C there is a decrease in crystallite size, most likely due to subdivision of the grains at the dislocation boundaries. [Preview Abstract] |
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P1.00031: Spectroscopic Studies of Azul Maya: Novel Organic/Inorganic Complexes Layra Reza, Felicia Manciu, Brenda Torres, Lori Polette, Russell Chianelli Maya pigments are novel organic/inorganic hybrid materials with multiple technological applications. The materials are surface compounds formed by heating an organic molecule such as indigo with an inorganic compound such as palygorskite, which is a common clay. The organic molecule upon heating forms a strong interaction with the clay surface stabilizing both entities. This strong interaction is exhibited through a color change from deep blue to the well-known Maya Blue indicating an exchange of electron density at the surface. Analysis by infrared absorption and Raman spectroscopy demonstrate the disappearance of nitrogen-hydrogen (N-H) bonding, as the indigo molecule incorporates into the inorganic palygorskite material. Infrared data confirm the loss of zeolitic water and a partial removal of structural water after the heating process. Carbon and oxygen studies at Stanford Synchrotron Radiation Laboratory by X-Ray photoemission spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS), respectively, suggest possible cationic (Al$^{+3})$ bonding of the organic molecule to palygorskite compound. [Preview Abstract] |
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P1.00032: Measuring the Size Dependence of the Magnetic Properties of Alkanethiol-coated Gold Nanocrystals Sarah C. Hernandez, Brian A. Korgel, Andrew Heitsch Bulk gold is diamagnetic but 2 nanometer dodecanethiol capped gold nanoparticles have been reported to exhibit ferromagnetic properties.[1] Ferromagnetism is believed to result from spin-orbit coupling between the surface-bound thiol molecules and the gold surface atoms.[2] Therefore, as the gold nanoparticles size decreases and the surface area to volume ration increases, ferromagnetism is expected to increase. The size dependence of the magnetic properties of thiol-capped gold nanocrystals was studied. Thiol-capped gold nanocrystals were synthesized using Brust's method[3] with diameters that ranged from 2 to 6 nm. The magnetic susceptibility of the nanocrystals were measured using a superconducting quantum interference device at room temperature and 5 Kelvin.[1] Contrary to two published reports,[1,2] but consistent with another study,[4] the thiol-coated gold nanocrystals did not exhibit ferromagnetism, and were in fact diamagnetic, even down to diameters of 1.8 nm. [1] Crespo, P., \textit{et al.} \textit{Phys. Rev. Lett.} \textbf{93} (2004) 087204. [2] Hernando, A., \textit{et al. Phys. Rev. Lett.} \textbf{96} (2006) 057206. [3] Brust, Mathias, \textit{el al.} \textit{J. Chem. Soc., Chem. Commun.,} (1994) 801. [4] Yamamoto, Y.; Hori, H., \textit{Re. Adv. Mater. Sci. }\textbf{12} (2006) 23-32. [Preview Abstract] |
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P1.00033: Characterization of Dye Laser Materials Pumped by a TEA Nitrogen Laser Alan Martinez, James Espinosa, James Espinosa TEA (Transverse Electrical excitation at Atmospheric pressure) Nitrogen lasers are relatively easy to produce and can be constructed from items that can be found in the lab. Because it is so readily accessible and cost effective, we constructed a working model to be used as a test bed for a number of materials to test their use as dye lasers. The TEA laser emission is optimized to be used as a pump source to excite potential dye materials in order to achieve lasing. We measure the output of the dyes and report our preliminary results. [Preview Abstract] |
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P1.00034: Nonlinear Optics: Efficient Second Harmonic Generation and Difference Frequency Generation David Marvin, Ali Khademian, David Shiner Second Harmonic Generation is a well-known phenomenon caused by polarized light passing through a crystal with nonlinear optical properties. The crystal's nonlinear polarizability will cause the formation of a second wave of light that has a frequency which is double that of the incident light. This effect also leads to frequency mixing, in which for instance two lasers of different frequencies can combine to create a sum or difference frequency, which is useful, for example, in the creation of more broadly tunable laser sources. However, with the power levels commonly available in continuous wave laser sources ($\sim $ 1 W), the nonlinear polarizability produces a small effect; only a small amount of the source light is converted into second harmonic light. Several techniques can be used to amplify the effect in order to obtain a useful amount of frequency converted light. We are using a commercially available Periodically Poled Lithium Niobate (PPLN) crystal in a waveguide configuration, along with efficient mode matching, in an effort to produce a potentially efficient, tunable frequency mixing system. Current results (60{\%} mode coupling and 300{\%}/W/cm) and future directions will be presented. [Preview Abstract] |
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P1.00035: Angular Dependency and Kinematics of Light Atom Nuclear Reactions with Positive Q Values Jose Pacheco, Fabian Naab, Daniel Marble, Jerome Duggan Einstein's relationship, E=mc\^{}2 implies that energy can be changed into mass and vice versa. Using nuclear reaction analysis, the interchange of mass into energy can be used to analyze trace elements in a material since each given element has a set of nuclear reactions that are unique to it. These nuclear reactions have positive Q values, which show up as excess energy in the emitted particle spectrum. However accurate interpretation of these spectra for materials analysis can be complicated as knowledge of both the angular dependency of the reaction and the geometry of the detection setup is required. The angular dependence is usually easily taken into account provided the reaction is well known and there are no nuclear interferences. In this experiment, a 1 MeV proton beam from a 2.5 MeV Van De Graff was applied to targets made up of light atoms, mainly 7Li, 6Li, and 19F. The results demonstrate the importance of accurately knowing the detection configuration, geometry, and the effect of detection system resolution when doing NRA. For instance, our system failed to give any information about the nuclear reaction for angles less than 30 degrees from the incoming beam due to its resolution. [Preview Abstract] |
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P1.00036: Infrared Spectroscopy of Germanium-Carbon Clusters: $\nu_4(\sigma_u)$ mode of GeC$_5$Ge Eric Gonzalez, C.M.L. Rittby, W.R.M. Graham Recent results will be presented from FTIR (Fourier transform infrared) and DFT (density functional theory) studies of the vibrational fundamentals and structures of germanium-carbon clusters trapped in solid Ar. The linear germanium-carbon cluster GeC$_5 $Ge has been detected using FTIR spectra generated when products from the dual laser evaporation of Ge and C rods are trapped in solid Ar matrices at $\sim$10 K. Comparison of frequencies and $^{13}$C isotopic shift measurements with the predictions of DFT calculations at the B3LYP/cc-pVDZ level confirms the identification of the $\nu_4(\sigma_u)$ mode of GeC$_5$Ge at 2158.0 cm$^{-1}$. [Preview Abstract] |
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P1.00037: Thin Film Analysis Using Rutherford Backscattering Spectrometry (RBS), and Particle Induced X-Ray Emission (PIXE) Jose Pacheco, Fabian Naab, Daniel Marble, Jerome Duggan The construction of a modern electronic device usually involves many deposition processes and materials. In addition to the controlling impurities and stoichiometry of the deposited film, the thickness of these films must also be carefully controlled to obtain device scaling, an essential requirement for obtaining faster, smaller, and more efficient electronic devices. We report on the suitability of RBS and PIXE to determine both film thickness and elemental composition on several materials of interest to the electronics industry. RBS and PIXE was used to determine film thickness of evaporated thin films (approx. 1000 angstroms) of Au, Cu, and Ge on silicon substrates samples as well as secondary standards of Rh, and Ge with known thicknesses. RBS was also used to analyze commercial infrared detectors of known composition sent to us by a semiconductor manufacturer. Our results show that our RBS and PIXE measurements are in close agreement for thickness and compositions of the known standards and to film thickness measurements for the deposited films obtained using a film deposition monitor. [Preview Abstract] |
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P1.00038: Wave particle diffusion of energetic ring current ions Samuel Jones, Mei-Ching Fok, Konstantin Gamayunov, George Khazanov Electromagnetic Ion Cyclotron (EMIC) waves are known to be generated in the ring current by pitch-angle anisotropy. These waves produce wave-particle interactions which can cause significant diffusion of ions with energies above the wave resonance. We incorporate pitch angle diffusion calculated from EMIC amplitude and plasmaspheric density into the Comprehensive Ring Current Model (CRCM). Using this model we study loss cone depletion of energetic ions during various magnetic storm events including the superstorm of 20 November 2003. We compare the simulated decay rates to those observed by IMAGE/HENA and other particle precipitation data. [Preview Abstract] |
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P1.00039: Alfv\'{e}nic Accelerated Electrons and Auroral Kilometric Radiation Observed by the FAST satellite Lun Ma, Yi-jiun Su, Samuel Jones, R.E. Ergun Evidence of the coexistence of Alfv\'{e}n waves and Auroral Kilometric Radiation (AKR) will be presented. Previous studies suggested two types of electron maser instabilities to be the generation mechanism of AKR: one is the loss cone maser; the other is the ``shell'' maser. The ratio of plasma frequency to electron cyclotron frequency should be small in order to trigger the instability predicted by the weakly relativistic electron cyclotron maser theory. One case has been found where narrow band emissions are associated with multiple shell electron distributions in a dynamic Alfv\'{e}nic acceleration region. More observational evidences will be presented. [Preview Abstract] |
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P1.00040: Simulation of the formation of O+ density troughs in the polar cap magnetosphere using the UT Arlington DyFK model Fajer Jaafari, James Horwitz, Wen Zeng Measurements of the O$^{+}$ densities in the polar cap near 5000 km altitude display normal and low density (trough) regions. In this presentation, we use the UTA Dynamic Fluid-Kinetic (DyFK) model to simulate such O$^{+}$ density profiles observed by the Thermal Ion Dynamics Experiment (TIDE) on the POLAR spacecraft. Using solar wind parameters and incorporating Cleft Ion Fountain effects for these events to drive a time-varying high-latitude convection model and auroral processes of soft electron precipitation, we simulate the evolving high-latitude ionospheric plasma transport and associated parameter profiles for several convecting flux tubes in the high-latitude ionosphere-magnetosphere system. For the convection patterns thus computed, these flux tubes nominally intersected the POLAR trajectory where the density measurements were made. It is found that, owing chiefly to F-region recombination processes during trajectory segments when the low altitude portions of such flux tubes in darkness, as well as incorporating CIF effects in the dayside auroral region, normal and low trough-like densities at higher altitudes developed along some of these flux tubes. The simulations of the density profiles for these flux tubes will be compared with measured POLAR/TIDE-measured O$^{+}$ densities for inside and outside of these regions. This work was completed under financial support by NASA grant NNG05GF67G and NSF grant ATM-0505918 to the University of Texas at Arlington. [Preview Abstract] |
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P1.00041: Development of Ti-sheathed MgB$_{2}$ Superconducting Wires with Very High Current-carrying Capability Hui Fang, Gan Liang, Cad Hoyt, Shelley Keith, M. Hanna, M. Alessandrini, F. Yen, B. Lv, Z. Tang, K. Salama Ti-sheathed MgB$_{2}$ wires with very high magnetic critical current density ($J_{c})$ have been fabricated with the \textit{in situ} powder-in-tube method. The wires were characterized by magnetization, electrical resisitivity, x-ray diffraction and scanning electron microscopy measurements. At 5 K, the magnetic $J_{c}$ measured in magnetic fields of 2 Tesla (T) and 5T are about 4.1 $\times $ 10$^{5}$ A/cm$^{2}$ and 7.8 $\times $ 10$^{4}$ A/cm$^{2}$, respectively. The $J_{c}$ value at 20 K and 0.5 T is 3.6 $\times $ 10$^{5}$ A/cm$^{2}$. The superconducting volume fraction for the core material of the MgB$_{2 }$wires is about 71{\%}. These results show that the magnetic $J_{c}$ for the present Ti-sheathed MgB$_{2}$ wires is substantially higher (40{\%}-300{\%} higher) than the best magnetic $J_{c}$ results available for the Fe-sheathed MgB$_{2}$ wires made by similar processes. Because of such excellent $J_{c}$, it is anticipated that the Ti-sheathed MgB$_{2}$ wires developed by the present technique are very promising for future lightweight superconducting magnet applications. [Preview Abstract] |
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P1.00042: Physical and Tribological properties of fluorine functional group containing epoxy resin cured with polyamine Wunpen Chonkaew, Witold Brostow, Kevin Menard A fluoro-epoxy monomer was synthesized and blended with commercial diglycidyl ether of bisphenol A in the ratio of 2.5 to 20 {\%}. The products obtained were cured with polyamine hardener at 25$^{o}$C. The dynamic mechanical and physical properties, such as curing behavior and thermal stabilities, were investigated and compared with pure commercial epoxy system. For the tribological behavior, the scratch depth and friction determination were performed. We have found that the friction of all blend systems is lower than for the pure commercial system. However, only blend systems with low percent of the fluoro-epoxy monomer show the improvement in scratch resistance. [Preview Abstract] |
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P1.00043: Mechanism of Arsenic Adsorption Using Wheat Biomass -- a spectroscopic study Oscar Calvo, Felicia Manciu, Josefina Maldonado, Jorge Gardea-Torresdey Arsenic is a trace element that is toxic to animals, humans included. Since the current Environmental Protection Agency guidelines regarding water quality standards indicate that arsenic concentrations in excess of 50 ppb are hazardous to welfare of humans, the search for new water remediation methods or improvements of previous methods have been a focus in environmental technology. Investigations of arsenic uptake have used wide range of sorbents including iron oxides and oxyhydroxides, for which it have been proved that arsenic shows high affinity. In this study, we used far-infrared spectroscopy to examine the arsenic reduction using biomaterials. pH dependence analysis by FTIR demonstrates the sorption of iron oxides and oxyhydroxides by the wheat biomass. The splitting of 350 cm$^{-1}$ amorphous iron oxide vibrations is a direct proof of the arsenic uptake. In addition, there is evidence of sorption of arsenic at sulfhydryl group of cysteine existent in wheat. [Preview Abstract] |
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P1.00044: UV curable hard coatings on polyesters Tea Datashvili, Witold Brostow, David Kao UV curable, hard and transparent hybrid inorganic-organic coatings with covalent links between the inorganic and the organic networks were prepared using organically crosslinked heteropolysiloxanes based on the sol-gel process. The materials were applied onto polyester sheets and UV cured. The deposition was followed by a thermal treatment to improve mechanical properties of the coatings. High light transmission and the resulting thermophysical properties indicate the presence of a nanoscale hybrid composition. The coatings show excellent adhesion to polyesters even without using primers. Further mechanical characterization shows that the coatings provide high hardness and good abrasion resistance. [Preview Abstract] |
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P1.00045: Characterization of the Polymorphic Composition of a Pharmaceutical: Chlorpropamide Elizabeth Stockton, Lauren Chudej, Bryan Bilyeu, Witold Brostow Chlorpropamide is polymorphic. It exhibits three principal crystal forms, depending on crystallization conditions, but can transform from one form to another under certain conditions. Since different crystal forms affect both industrial processing and pharmacological activity, characterization of the crystal form or forms is very important in dosing and storage. Since the melting points of the three crystal forms of chlorpropamide are very close, but the enthalpies are very different, differential scanning calorimetry (DSC) is an obvious choice to identify the melting peaks and quantify the energy associated with each. The three pure crystal forms were prepared and the melting points and enthalpies of fusion determined. Samples cooled from the melt were found to be semi-crystalline, with a large amorphous component. However, with annealing, the amorphous component reorganized into a crystal form. Mixtures of two crystal forms were prepared and scanned for melting points. The mixtures showed two distinct melting points for the two components, from which the melting points were determined for identification. The enthalpy of fusion was calculated to determine the relative amount of each crystal form. [Preview Abstract] |
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P1.00046: Extension of Barta's Bounding Theorem to Pseudo Hermitian Hamiltonians Carlos Handy We present some initial results in the extension of Barta's Bounding Theorem to Pseudo Hermitian Hamiltonians, which have attracted much attention in the recent literature. [Preview Abstract] |
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P1.00047: Future Application of Euclidean Triangles in Physics S. Kalimuthu In this work, we discuss the future application of Euclidean triangles in physics. [Preview Abstract] |
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P1.00048: Newton's Atom Andrea Chaney, James Espinosa, James Espinosa At the turn of the twentieth century, physicists and chemists were developing atomic models. Some of the phenomena that they had to explain were the periodic table, the stability of the atom, and the emission spectra. Niels Bohr is known as making the first modern picture that accounted for these. Unknown to much of the physics community is the work of Walter Ritz. His model explained more emission spectra and predates Bohr's work. We will fit several spectra using Ritz's magnetic model for the atom. The problems of stability and chemical periodicity will be shown to be challenges that this model has difficulty solving, but we will present some potentially useful adaptations to the Ritzian atom that can account for them. [Preview Abstract] |
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P1.00049: Is Hideki Yukawa's explanation of the strong force correct? Victor Vasiliev, Russell Moon Reexamining Hideki Yukawa's explanation of the strong force using the principles of the Quark Theory and the Vortex Theory, it was discovered that it is possible for a virtual particle to be passed back and forth between the proton and the neutron. This discovery creates a new and revolutionary explanation of the strong force of nature. The creation of the strong force appears to be the combination of four processes at work in the nucleus: virtual particles, intrinsic magnetism, ``nuclear gravity'', and gluons. 1. V.V. Vasiliev, R.G. Moon, The bases of the vortex theory, Book of abstracts The 53 International Meeting on Nuclear Spectroscopy and Nuclear structure St. Petersburg, Russia, 2003, p.251. 2. H. Yukawa, Tabibito, (World Scientific, Singapore, 1982), p. 190-202. 3. K. Gridnev, V.V. Vasiliev, R.G. Moon, The Photon Acceleration Effect, Book of abstracts, OMEGA 5 -- Symposium on Origin of Matter and Evolution of Galaxies, Nov 8-11, University of Tokyo, Tokyo Japan. 4. R.G. Moon, V.V. Vasiliev. Explanation of the Conservation of Lepton Number, Book of abstracts LV. National Conference on Nuclear Physics, Frontiers in the Physics of Nucleus, June 28-July 1, 2005, Saint-Petersburg, Russia, 2005, p. 347.5. . [Preview Abstract] |
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P1.00050: Application of the Hyperspherical Hidden Crossing Method to Near-Threshold Positron-Hydrogen Ionization Krista Jansen, S.J. Ward, J.H. Macek, J. Shertzer We have applied the hyperspherical hidden crossing method [1] to compute the S-wave cross section for near-threshold e$^+$-H ionization. We confirm the second order correction terms to the Wannier threshold law that were previously derived [2]. The small S-wave cross section is due to destructive interference between the two amplitudes that correspond to different paths leading to Ps formation. \newline \newline [1] J. H. Macek and S. Yu.Ovchinnikov, Phys. Rev. A {\bf 54}, 544 (1996). \newline [2] W. Ihra, J. H. Macek, F. Mota-Furtado and P. F. O'Mahony, Phys. Rev. Lett. {\bf 78}, 4027 (1997), James Sternberg, S. J. Ward, J. H. Macek and J. Shertzer, Bull. Am. Phys. Soc. {\bf 49}, no.3, p.52 (2004). [Preview Abstract] |
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P1.00051: A Deperturbation Method to Aid in the Interpretation of Infrared Spectra Guillermo Garcia, Magnus Rittby Theoretical predictions of fundamental vibrational frequencies of molecules and their corresponding frequency shifts caused by isotopic substitutions are useful in identifying new molecular species. The application of this technique can break down when vibrational fundamentals are close in frequency. The predicted isotopic shifts can then become highly sensitive to the full force constant matrix. Such is for example the case in the study of the vibrational spectra of long carbon chains. The deperturbation method presented here is introduced in an attempt to shed more light on this problem as well as to provide a means to extend the original approach of using predicted isotopic shifts to interpret experimental spectra. Using perturbation theory we show that the second order contribution to the isotopic frequency shift can be completely eliminated when combining data from appropriately selected isotopomers, eliminating the lowest order (near) resonant contribution to the isotopic frequency shift. We present the derivation of the model as well as illustrative examples and comparison with existing experimental data. [Preview Abstract] |
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P1.00052: The Geomagnetic Spectrometer observed by POLAR/TIDE and simulated by the UT Arlington DyFK transport model Wen Zeng, James Horwitz, Heather Elliott, Thomas Moore Observations of characteristic streaming energies of outflowing ionospheric ions in the polar cap magnetosphere by approximately noon-midnight orbiting spacecraft frequently indicate a decline of the ion streaming energies from dayside to the night side. When multiple ion species are detected, generally an ion species separation is observed in which for similar energies, H$^{+}$ tends to be confined closer to the dayside ion source, followed by He$^{+}$ and O$^{+}$ toward the nightside. These effects can be viewed as resulting from a natural geomagnetic mass spectrometer. Here we compare ion streaming energy observations by the Thermal Ion Dynamics Experiment (TIDE) on POLAR with ionospheric plasma transport simulations using the UT Arlington Dynamic Fluid Kinetic (DyFK) model. Using realistic parameters for soft electron precipitation and wave-particle heating levels for the creation of the ionospheric cleft ion fountain (CIF) source region, as well as realistic convection values, the DyFK simulations show good agreement with measurements of the ion streaming energies along the POLAR orbit through the polar cap magnetosphere. The POLAR orbit in these cases typically covered an altitude range of 2 to 8 R$_{E}$ as the spacecraft traversed the polar cap magnetosphere. These and related results will be presented and discussed. This work was completed under financial support by NASA grant NNG05GF67G and NSF grant ATM-0505918 to the University of Texas at Arlington. [Preview Abstract] |
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P1.00053: Evaluation of a Novel Design for an Electrostatic Quadrupole Triplet Ion Beam Lens L.R. Burns, J.D. Bouas, S. Matteson, D.L. Weathers We describe the design and evaluation of an electrostatic quadrupole triplet lens constructed to focus ion beams of up to 200 keV in energy. The lens is very compact and incorporates a feature to induce octupole fields that can correct for spherical and other octupole-order aberrations. Two methods were used to evaluate the lens: observation of the focused beam spot on a specially fabricated target while systematically varying lens voltages, and the grid-shadow technique. The latter demonstrated that octupole-order aberrations were completely corrected in one direction when the lens quadrupoles were operated individually with appropriate octupole excitations. [Preview Abstract] |
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P1.00054: Modeling Guard Type LWD Tool with Comsol Multiphysics Gary Noe, Brian Oetiker Well logging is the process of determining the properties of rock after drilling a borehole into the ground in search of oil. Companies are developing sensors that are placed on the drill pipe so that the information is made available while drilling (Logging While Drilling or LWD). This allows for operational decisions to be made during the process of drilling. One type of sensor measures the resistivity of the surrounding material by injecting current into the rock. Comsol Multiphysics software is used to model the response of the sensor as it passes through rock layers of various resistivity. The information gained from this model is used to calibrate the device and improve its design. [Preview Abstract] |
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P1.00055: Understanding the N*(1710) Resonance by Scanning the $\pi ^{-}p$ System in the (1610-1770) MeV Region Temitope Omiwade Abilene Christian University in collaboration with Petersburg Nuclear Physics Institute (PNPI) and Institute for Theoretical and Experimental Physics (ITEP) have been working to improve the pion-nucleon resonance by scanning of the $\pi ^{-}p$ system invariant mass in the (1610-1770) MeV region with the detection of $\pi ^{-}p$ and ${\rm K}\Lambda$ decays. Previous experiments indicate inconsistencies in the P$_{11}$(1710) resonance in the reaction $\pi ^{-}p \rightarrow \pi ^{-}p$, however, using the reaction $\pi ^{-}p \rightarrow {\rm K}\Lambda$, the nucleon resonance can be understood better. Using a GEANT4 simulation, we were able to model the particles from the target and retrieve information on these particles from the hodoscope. Using ROOT, a detailed analysis was retrieved from the data to differentiate between the protons and pions at the hodoscope. The goal of my work is to provide criteria for discrimination of proton from pion tracks in the final state using the TOF system. [Preview Abstract] |
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P1.00056: Data Acquisition in Research and Development of Resistive Plate Chambers for the Trigger Upgrade for the PHENIX experiment at RHIC John Wood To study the contributions of different flavors of quarks to the total spin of the proton, the PHENIX experiment at RHIC is installing a trigger system employing resistive plate chambers (RPC's). The trigger will allow data to be taken for the decay bosons produced in the parity-violating interactions of quarks during polarized p-p collisions at a much higher rate than without the upgrade. Prototypes of RPC's are being built with different materials and tested at the University of Illinois to determine characteristics such as position resolution, timing resolution, and rate capability. The data acquisition system for the test stand is presented in this poster. The system uses a number of CAMAC modules including a Jorway 73A crate controller. [Preview Abstract] |
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P1.00057: Volume of a black hole event horizon Brandon DiNunno, R.A. Matzner We describe, in detail, methods of calculating the volume of a black hole event horizon in different coordinate systems. While the process is relatively straightforward, we notice that some interesting properties arise when the coordinate systems are time-dependent, as in the case of Novikov and Kruskal coordinates. [Preview Abstract] |
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P1.00058: Evolution of grain size and morphology of Si thin films fabricated on lunar regolith glass C. Gramajo, L. Williams, A. Feltrin, A. Alemu, A. Freundlich A critical requirement for space colonization and in particular for its lunar exploration component is the availability of large amounts of electric energy. Novel architectures which involve the in situ manufacture of solar cells on the Moon using indigenous lunar materials have been proposed to meet this need [1]. In support of this effort, this study delves on several aspects of interest starting from the fabrication of a glass substrate from lunar regolith, to the deposition of Si films and the effects of thermal processing induced changes on the properties of these films. The experiments were implemented using several types of commercially available glasses as well as in-house fabricated regolith glass. In particular, the study provides valuable information on the effect of temperature on the interactions between Si and the substrates, and also the interaction between metallic contact layers and Si, which could affect regions beyond their common interface. This insight sheds a light on the evolution of grain size and morphology of Si thin films grown on lunar regolith. [Preview Abstract] |
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