Bulletin of the American Physical Society
76th Annual Meeting of the Southeastern Section of APS
Volume 54, Number 16
Wednesday–Saturday, November 11–14, 2009; Atlanta, Georgia
Session LA: Poster Session (5:00PM-6:45PM) |
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Room: Ballroom Foyer |
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LA.00001: No correlation discerned between the periods of rise and dominance of simulated species in a model of biological evolution Alan Kuhnle In [1], Liow et al. discern a general feature of the occurrence trajectories of biological species: the periods of rise and fall of a typical species are about as long as the period of dominance. In this work, an individual-based model of biological evolution that was developed by Rikvold and Zia in [2] is investigated, but no analogous feature is observed in the simulated species populations. Instead, the periods of rise and fall of a simulated species cannot always be sensibly defined; when it does make sense to define these quantities, they are quite short and independent of the period of dominance. \\[4pt] [1] Liow, L. H., Skaug, H. J., Ergon, T., Schweder, T.: Global occurence trajectories of microfossils: Is the rise and persistence of species influenced by environmental volatility? Manuscript for Paleobiology, 5 Dec 2008 \\[0pt] [2] Rikvold, P.A., Zia, R.K.P.: Punctuated equilibria and 1/$f$ noise in a biological coevolution model with individual-based dynamics. Physical Review E \textbf{68}, 031913 (2003) [Preview Abstract] |
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LA.00002: Performance of 5000 students in introductory mechanics Marcos Caballero, Keith Bujak, Matthew Kohlmyer, Richard Catrambone, M. Jackson Marr, Michael Schatz We present the performance of nearly 5000 students on a standardized assessment of force and motion (Force Concept Inventory) for two fundamentally different physics curricula; a traditional course based on the Knight text and a reform course based on the text of Chabay and Sherwood, Matter and Interactions (M\&I). The traditional course is a standard physics curriculum with particular emphasis on constant force motion. The M\&I course is a modern approach to physics instruction with computer modeling and an emphasis on the generality and dynamics of Newton's Second Law. We find poorer performance for students who have taken the M\&I course as compared to students taking the standard course. This under-performance is consistent despite the superior performance by M\&I students on common exam problems in other areas of mechanics. We offer explanations for this consistent under-performance in the realm of force and motion as well as some results from recent work to combat these misconceptions in the M\&I course. [Preview Abstract] |
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LA.00003: The Use of Clicker Questions in Modern Physics R. Seth Smith Turning Point software was used to create new classroom presentations for FMU's modern physics class during the spring of 2009. Turning Point is essentially Power Point, but it provides one with the ability to embed interactive questions within a presentation. Every student in the class responds to these questions by using radio frequency devices known as ``clickers''. This gives the professor immediate feedback on the level of understanding for an entire class. An analysis of the effectiveness of this approach in modern physics will be presented, including examples of the clicker questions that were used for various modern physics topics. [Preview Abstract] |
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LA.00004: Developing a cross over curriculum about topics that affect all members of our world Donald Franklin Our educational system needs a cross over curriculum program which helps students to evaluate observations that allow for energy solutions in our world. Energy Solutions Foundations has developed three DVD teacher kits which contain materials for the classroom teacher to have profession contact with Engineers to help make the lessons much more believable. As this method is explored during multiple semesters, we should see a major change in the students as they will be learning to apply academic knowledge into a career choice. Classes are no longer about books of facts and skills, but the depth persons and populations were able to agree to develop energy for their community, based on a set of values. All attendees will be given the three DVD's from Energy Solutions Foundations. The DVD's are titled: Alphas, Betas, Gammas, Oh My! Nuclear Energy and the Use of Nuclear Materials, Nuclear is Hot! Everything you wanted to know about Nuclear Science But Were Afraid to Ask. [Preview Abstract] |
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LA.00005: Fighting for physics and Earth science in Florida's high schools Paul Cottle During its Spring 2009 session, the Florida Legislature considered a bill that would have suspended its comprehensive standardized test in high school science and substituted an end-of-course test in biology to satisfy the requirements of the No Child Left Behind (NCLB) Act. By doing so, the bill would have further deemphasized high school physics and Earth science in a state where physics courses are sometimes not available in high schools (even in International Baccalaureate programs) and where the state's own statistics say that only 16\% of high school graduates have taken a physics course. A group of about one hundred science faculty from thirteen colleges and universities in Florida responded with a letter to Governor Crist and visits to legislators asking that the biology-only provisions be defeated (and they were). The group has now produced a white paper on high school science requirements that has been distributed to government and business leaders and been publicized via op-ed pieces and news items in several media outlets statewide. This poster will describe the situation in Florida and the faculty group's efforts. It will also compare Florida's high school requirements in science with those in the other SESAPS states. [Preview Abstract] |
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LA.00006: Assessing the Effectiveness of Studio Physics in Introductory-Level Courses at Georgia State University Brianna Upton, John Evans, Cherilynn Morrow, Brian Thoms Previous studies have shown that many students have misconceptions about basic concepts in physics. Moreover, it has been concluded that one of the challenges lies in the teaching methodology. To address this, Georgia State University has begun teaching studio algebra-based physics. Although many institutions have implemented studio physics, most have done so in calculus-based sequences. The effectiveness of the studio approach in an algebra-based introductory physics course needs further investigation. A 3-semester study assessing the effectiveness of studio physics in an algebra-based physics sequence has been performed. This study compares the results of student pre- and post-tests using the Force Concept Inventory. Using the results from this assessment tool, we will discuss the effectiveness of the studio approach to teaching physics at GSU. [Preview Abstract] |
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LA.00007: ABSTRACT WITHDRAWN |
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LA.00008: Radical Rearrangement Catalysis in an Enzyme at 190-207 K: Mechanistic Features Revealed by Substrate $^{1}$H/$^{2}$H Isotope Effects Chen Zhu, Kurt Warncke The decay kinetics of both the natural abundance and [1,1,2,2-$^{2}$H$_{4}$]-aminoethanol generated Co$^{II}$-substrate radical pair catalytic intermediate in ethanolamine ammonia-lyase (EAL) from \textit{Salmonella typhimrium} have been measured by using time-resolved, full-spectrum X-band continuous-wave electron paramagnetic resonance (EPR) spectroscopy in frozen aqueous solution from 190 to 207 K. The decay reaction proceeds through sequential radical covalent rearrangement and hydrogen atom transfer (HT) steps. In the temperature range from 190 to 207 K, the decay is biexponential, and the two phases correspond to distinct populations [1]. The $^{1}$H/$^{2}$H isotope effects (IE) on the fast phase and slow phase are 1.3 and 0.8, respectively. These IE are not caused by a primary kinetic IE. Therefore, HT is rapid, relative to rearrangement. We propose that the fast phase is rate-determined by the rearrangement step, and that the slow phase is rate-determined by a step after rearrangement that is associated with protein guidance of the reactions. The results reveal microscopic features of the core reaction chemistry and protein dynamics participation in the reaction, which are not accessible at ambient temperatures.\\[4pt] [1] Zhu, C., Warncke, K. \textit{Biophys. J. 95}, 5890 (2008). Supported by grant DK54514 from NIDDK/NIH. [Preview Abstract] |
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LA.00009: A Bio-Inspired Catalyst for CO$_{2}$ Reduction Adonis Bovell, Kurt Warncke Efficient storage of solar energy is critical for the next generation of solar energy conversion systems. Herein is described a catalytic module, using the robust TIM barrel fold of the EutB subunit of ethanolamine-ammonia lyase (EAL), for high specificity recognition and light-driven reduction of CO$_{2}$ to energy rich biofuels. EAL catalyzes the deamination of ethanolamine via a free radical mechanism, by using an adenosylcobalamin (AdoCbl) cofactor. Our aim is to use the reducing power of the cobalt(I) form of the cofactor to drive the reduction of CO$_{2}$. Molecular biology techniques have been used to generate histidine-tagged EutB subunits of EAL for high throughput protein purification. The binding of cobalamins to EutB was probed by using tryptophan fluorescence quenching. The Hill constant ($K_{H})$ and coefficient ($n_{H})$ for AdoCbl-EutB binding were determined as 33 $\mu $M and 1.3, respectively. The results show that cob(III)alamin binds to isolated EutB, and suggest that Co(II) and Co(I) states will also bind. Rational active site modifications of EutB will be made to facilitate specific CO$_{2}$-Co(I) binding and to introduce a proton delivery network. The results will give insight into the challenging task of rational enzyme design. [Preview Abstract] |
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LA.00010: Developing a Biologically-Inspired Molecular Solar Energy Conversion Device: Reaction of Solution and Protein-Bound Cobalamins with Carbon Dioxide and Halo-Organic Compounds Wesley D. Robertson, Nathan M. Ennist, Kurt Warncke Our aim is to design and construct protein-based artificial photosynthetic systems that reduce carbon dioxide (CO$_{2})$ and toxic halo-organic compounds within the robust and adaptable ($\beta \alpha )_{8}$ TIM-barrel protein structure. The EutB subunit of the adenosylcobalamin-dependent enzyme, ethanolamine ammonia-lyase (EAL), from \textit{Salmonella typhimurium}, was selected as the protein template. The Co$^{I}$ forms of the native cobalamin (Cbl) cofactor and a derivative, cobinamide (Cbi), possess relatively low redox potentials that are commensurate with reduction of CO$_{2}$ and halo-organic compounds. Titanium$^{III}$ citrate and pulsed laser-excited 5'-deazariboflavin (5'-DRF) were used to reduce Cbl or Cbi. UV/visible absorption spectroscopy was used to monitor the reaction kinetics of reduced Cbl and Cbi with CO$_{2}$ and halo-organics, and 13C-NMR was used for product analysis. The results provide fundamental information for development of an organocobalt-based protein-catalytic device for stable fuels generation and toxic chemical remediation. [Preview Abstract] |
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LA.00011: Photoionization of Ce$^{3+}$ and Ce$^{3+}$@C$_{60}$ Zhifan Chen, Alfred Z. Msezane Photoionization of the Ce$^{3+}$ and Ce$^{3+}$@C$_{60}$ in the energy region 100-150 eV has been studied using our recently developed random phase approximation with exchange method and model potential for the C$_{60}$ fullerene. Comparison of the ressults of the Ce$^{3+}$ photoionization with a recent measurement confirms the value of the measured cross section for Ce$^{3+}$ and indirectly supports the observed suppression effect of the carbon cage in the endohedral fullerene Ce@C$^+_ {82}$ photoionization. Our calculation of the Ce$^{3+}$@C$_{60}$ photoionization process demonstrates both the suppression and the resonance effect of the C$_{60}$ shell. [Preview Abstract] |
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LA.00012: Nonlinear Optical Characterizations of Phosphonite-substituted Bithiophenes Yuanli Zhang, Jianwei Wang, Christopher Lawson, Jason Freeman, Gary Gray An optical power limiter (OPL) is a device used to protect human eyes and optical sensors from damage from high intensity light sources. Researchers have studied OPL's in the various spectral regions, but there are little or no published reports of OPL in the blue spectral region. Phosphonite-substituted bithiophenes, which show little linear absorption at blue spectral region, have potential applications as OPL's due to their strong nonlinear optical (NLO) absorption in the blue spectral region. We study of a number of new phosphonite-substituted bithiophenes complexes for blue OPL applications. The NLO properties are characterized by direct transmission and Z-scan measurements. [Preview Abstract] |
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LA.00013: Pyroelectric and Electrical Transport Properties of Silver Nanoparticles Doped LiTaO$_{3}$:P(VDF-TrFE) Films John Corda, Ashok Batra, Padmaja Guggilla, Mohan Aggarwal, Tatiana Kukhtareva, Matthew Edwards Ferroelectric ceramic and polymer composites are a well-established alternative to conventional ferroelectrics for sensors and actuator applications because they combine the mechanical compliance and flexibility of polymer with the high piezoelectric and pyroelectric activities of electro-ceramic. Lithium tantalite (LiTaO$_{3})$ ceramic particles and silver nanoparticles have been incorporated into a polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE) 70/30 mol{\%}] copolymer matrix to form composite films via solution casting technique. Both of these materials have excellent ferroelectric and pyroelectric properties. Electrical properties such as the dielectric constant, dielectric loss, conductivity and pyroelectric coefficient have been measured as a function of temperature. Their results obtained shall be presented including composite films' usefulness in infrared detection devices. [Preview Abstract] |
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LA.00014: Structural studies on the phase stability of In$_{1-x}$ Ga $_{x}$N layers Goksel Durkaya, Ramazan Atalay, Max Buegler, Mustafa Alevli, Muhammad Jamil, Ian Ferguson, Nikolaus Dietz The In$_{1-x}$ Ga $_{x}$N ternary alloy system has potential for development of high efficiency solar energy conversion and advanced optoelectronic device applications. Ga$_{1-x}$ In $_{x}$N / In$_{1-x}$ Ga $_{x}$N hetero-structures of various compositions can be engineered to the responsive from UV to IR wavelength regime. However, the growth of such ternary In1-xGaxN alloys is challenging due to high lattice mismatch, interfacial fields and phase segregation. This contribution focuses on the phase stability of In$_{1-x}$ Ga $_{x}$N layers grown by `high-pressure chemical vapor deposition (HPCVD). We present the results of the structural and optical studies on the phase stability of In$_{1-x}$ Ga $_{x}$N layers using Raman spectroscopy (RS), X-Ray Diffraction (XRD), Optical Transmission Spectroscopy (OTS) and Atomic Force Microscopy (AFM). The effect of growth parameters and conditions; V/III ratio, growth temperature and precursor injection scheme, on phase segregation of In$_{1-x}$ Ga $_{x}$N layers and on metallic Indium adlayer formation on surfaces are presented. The effects of phase segregation on the surface topography are studied by AFM. [Preview Abstract] |
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LA.00015: Nonthermal Laser Assisted Ge Quantum Dot Formation on Si(100)-2x1 by Pulsed Laser Deposition Ali Er, Hani Elsayed-Ali The effect of laser-induced electronic excitations on the self-assembly of Ge quantum dots (QDs) on Si(100)-2x1 grown by pulsed laser deposition is studied. The samples were first cleaned by using modified Shiraki method and then transferred into the deposition chamber. The vacuum system was then pumped down, baked for at least 24 hours, and the sample was then flashed to 1200 \r{ }C in order for the 2x1 reconstruction to form. The experiment was conducted under a pressure $\sim $1x10$^{-10}$~Torr. A Q-switched Nd:YAG laser was used to ablate a Ge target. In-situ RHEED and STM and ex-situ AFM were used to study the morphology of the grown QD. The dependence of the QD morphology on substrate temperature and ablation and excitation laser energy density was studied. Electronic excitation is shown to affect the surface morphology. Laser irradiation of the Si substrate is shown to decrease the roughness of films grown at a substrate temperature of $\sim $400 $^{o}$C. Electronic excitation also affected the surface coverage, cluster density, uniformity and decreased the temperature required to form 3-dimensional QDs to $\sim $250 \r{ }C at which no crystalline film formation is possible without excitation laser. Possible mechanisms such as two hole localization following the phonon kick will be discussed. [Preview Abstract] |
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LA.00016: First-principles study of the photorefractive material KNbO$_{3}$ Mohua Bhattacharya, Steven P. Lewis, William M. Dennis, Gary Cook, Dean R. Evans The perovskite based material KNbO$_{3}$ has been studied extensively for its photorefractive properties, where the electro-optic effect combined with photoconductivity changes the local refractive index of the material in response to the incident intensities. The presence of a transition metal impurity like Fe is required for efficient photorefractive performance of this material. Recent experiments suggest that Ag co-doping enhances the photorefractive properties significantly. To shed light on the physical mechanism of this behavior, we perform first-principles calculations within the density functional theory framework. In this poster, we present the structural relaxation results for the different crystal forms that the pure host KNbO$_{3}$ can exist in at room temperature and higher. Preliminary calculations about the role of Fe on the geometric and electronic structures of KNbO$_{3}$ will also be presented. [Preview Abstract] |
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LA.00017: Composition and Structure of HPCVD-grown InGaN Ananta Acharya, Max Buegler, Goksel Durkaya, Brian Thoms, Nikolaus Dietz Group III-nitride semiconductors InN and GaN, along with their alloy InGaN, have been widely investigated due to their promising potential for light emitting diodes and lasers covering a wide spectral range from 0.7 eV to 3.4 eV. High pressure chemical vapor deposition (HPCVD) has been developed to allow the growth of heterostructures with a wide range of alloy compositions. In this work, compositional analysis of indium-rich InGaN films by Auger electron spectroscopy (AES) are presented. The similarity in energy of the nitrogen and indium AES peaks results in difficulty in determining the nitrogen to indium ratios using peak-to-peak heights in differentiated spectra. Using non-differentiated Auger electron spectra of InN and GaN for calibration, accurate determinations of composition for InGaN alloy films have been performed. Correlation of this compositional information with structural characterization by Raman spectroscopy and x-ray diffraction will be presented. [Preview Abstract] |
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LA.00018: All-optical control of surface plasmon polaritons using the MIT phase transition in a VO2 substrate Peng Xu, Irina Novikova, Kaida Yang, Cesar Clavero, Rosa A. Lukaszew We are interested in the possibility of achieving all-optical control over the properties of surface plasmon polaritons excited in an Au thin film by changing the properties of the substrate material. In particular, we are studying the effect of the metal-insulator transition in a VO${}_2$ film, that can be induced either by temperature variations or by the presence of an optical field on the surface plasmon resonance of Au overlayers. [Preview Abstract] |
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LA.00019: Investigating Anomalous Diffusion Using Fluorescence Correlation Spectroscopy Neil Anthony, Keith Berland Models used in fluorescence correlation spectroscopy (FCS) generally assume diffusion of a standard Fickian nature such that the mean square displacement (MSD,$\left\langle {\Delta r^2} \right\rangle )$ of the molecular diffusion is linearly proportional to time, i.e. $\left\langle {\Delta r^2} \right\rangle \propto t$. In complex systems the diffusion can be anomalous, which is commonly described \textit{via} a power law dependence of the MSD, i.e. $\left\langle {\Delta r^2} \right\rangle \propto t^\alpha $. When measuring anomalous dynamics using FCS, the correlation functions are typically measured over a single lengthscale and the anomalous exponent, $\alpha $, is recovered through curve fitting. The anomalous exponent accurately describes the time dependence of the diffusion over the measurement lengthscale, yet for the majority of experimental systems it has not yet been tested whether the dynamics predicted by the fit are actually observed over different lengthscales -- i.e. whether or not the assumed power law dynamics truly describe the system dynamics. We investigate using scanning FCS methods that simultaneously measure correlation functions over a range of lengthscales in order to determine how accurately the physical models describe the dynamics. We use simulations to test these methods and discuss their application for measuring drug delivery rates in biomedical hydrogels. [Preview Abstract] |
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LA.00020: Imaging waveguides using optical diffraction tomography Melissa Meister, Amy Sullivan Optical Diffraction Tomography measures changes in the index of refraction of a material rather than its light absorption. Therefore, this method can be used to quantitatively characterize objects that do not absorb light, such as waveguides. Better characterization of these objects and the materials from which they are created is necessary for the development of integrated optical systems. Unlike traditional imaging techniques, our system allows for imaging of micron-scale, low index contrast 3-dimensional structures that are deeply embedded in a polymer. The 3-dimensional target object is replicated at equal intervals to create a diffraction grating. A laser beam interacts with the grating to form a 2-dimensional diffraction pattern which we measure in the far field. This scattered electric field is directly related to the Fourier transform of the object's index profile. Taking data for a range of incident beam angles allows for the recreation of the 3-dimensional object. We demonstrate images of waveguides embedded in photopolymers with micron-scale resolution and a high signal-to-noise ratio. [Preview Abstract] |
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LA.00021: Hi-Q whispering gallery mode resonators in nonlinear crystals Matthew Simons, Eugeniy Mikhailov, Irina Novikova We report on the progress of developing nonlinear crystal-based whispering gallery mode resonators, which are circular cavities that support long-lived optical modes along their inside surface via total internal reflection. We have been refining our optical polishing techniques to produce lithium niobate ($LiNbO_3$) disks of $<1cm$ in diameter and $1mm$ in height. We have also been optimizing the process of coupling light into whispering gallery modes using frustrated total internal reflection from a rutile prism. In a $LiNbO_3$ disk with free spectral range of 5.1 $GHz$ coupled to a frequency-scanned diode laser centered around $\lambda = 795nm$, we achieved a quality factor on the order of $Q = 10^7$. This Q-factor is limited by the quality of polish on the surface, which we estimate to be $20$/$5$ scratch/dig. However, this is sufficiently high to support our goal of low-threshold non-critically phase-matched frequency conversion at near-infrared wavelengths. [Preview Abstract] |
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LA.00022: Electron Attachment in Low-Energy Electron Elastic Collisions with Au and Pt Atoms: Identification of Excited Anions A.Z. Msezane, A. Eure, Z. Felfli, D. Sokolovski The recent Regge-pole methodology has been benchmarked [1] on the accurately measured binding energies of the excited Ge\={ } and Sn\={ } anions [2] through the binding energies (BEs) extracted from the Regge-pole calculated elastic total cross sections (TCSs). Here the methodology is applied together with a Thomas-Fermi type potential that incorporates the vital core polarization interaction to investigate the possibility of forming excited Au\={ } and Pt\={ } anions in low-energy electron elastic collisions with Au and Pt atoms. From the positions of the characteristic extremely narrow resonances in the total cross sections, we extract the binding energies of the excited Au\={ } and Pt\={ } anions formed as Regge resonances during the collisions. The angular life of the complexes thus formed is used to differentiate the stable excited bound states of the anions from the shape resonances [3]. The BEs for the excited Au\={ } and Pt\={ } anions are found to be 0.475eVand 0.543eV, respectively, challenging both theory and experiment to verify. [1] A. Msezane \textit{et al}, Phys. Rev. A, Submitted (2009) [2] M. Scheer \textit{et al}, Phys. Rev. A \textbf{58}, 2844 (1998) [3] Z. Felfli \textit{et al}, Phys. Rev. A \textbf{79}, 012714 (2009) [Preview Abstract] |
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LA.00023: Charge transfer collisions of Si$^{3+}$ with H at low energies D.C. Joseph, J.P. Gu, B.C. Saha Charge transfer of positively charged ions with atomic hydrogen is important not only in magnetically confined plasmas between impurity ions and H atoms from the chamber walls influences the overall ionization balance and effects the plasma cooling but also in astrophysics, where it plays a key role in determining the properties of the observed gas. It also provides a recombination mechanism for multiply charged ions in X-ray ionized astronomical environments. We report an investigation using the molecular-orbital close-coupling (MOCC) method, both quantum mechanically and semi-classically, in the adiabatic representation. \textit{Ab} \textit{initio} adiabatic potentials and coupling matrix elements--radial and angular--are calculated using the MRD-CI method. Comparison of our results with other theoretical as well as experimental findings will be discussed. [Preview Abstract] |
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LA.00024: Calibration of Hypernuclear Missing Mass Spectra: Analysis of Various Target Effects Casey Neville, Joerg Reinhold Jefferson Lab Experiment E05-115 aims to accurately measure the absolute mass of lambda hypernuclei for ground as well as excited states. This will be accomplished in missing mass analysis in (e,e'K$^+$) reaction spectroscopy on various targets. This requires precise measurement of momenta as well as masses of all particles involved in the reaction. Measured momenta need to be corrected for energy loss in the target. Energy loss calculations and Monte Carlo studies have been performed to evaluate radiative and ionization energy loss in the various targets. Further, it has been noted that the currently listed value for the $\Lambda$-hyperon mass, used for spectrometer calibration, should be adjusted. The published measurement of this mass relied on outdated values for the proton, pion, and kaon masses. We have reevaluated this and arrive at a $\Lambda$-mass differing by about 10 keV from published values. [Preview Abstract] |
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LA.00025: Commissioning and Calibrating Bucking Coil System for HKS Water Cerenkov Detector Victor Maxwell, Joerg Reinhold Jefferson Lab Experiment E05-115 will perform a spectroscopic study of lambda hypernuclei for a wide mass region using the (e,e'K$^+$) reaction. Accurate detection of coincident kaons and electrons guarantees that a lambda hyperon has been produced within the nucleus. The High Resolution Kaon Spectrometer, whose instrumentation is composed of, among other devices, a water Cerenkov detector (WC), will be employed towards this end. The detector uses a series of photomultiplier tubes (PMT) to generate signals associated with particular events. In the fringe magnetic field of the spectrometer magnet, the PMTs' detection efficiency degrades significantly. Magnetic fields of equal strength and opposite orientation to the external field are created by applying current to bucking coils (BC) placed around the individual PMT. Data indicates a relationship between SPE emission rates, and collection efficiency distributions. Upon being placed in Hall C, this relationship has been used to set the appropriate current for each BC. [Preview Abstract] |
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LA.00026: Calibration Procedure of the HKS Time-Of-Flight System Rafael Badui, Joerg Reinhold Experiment E05-115 at Thomas Jefferson National Accelerator Facility is a spectroscopic study that will measure the excitation spectra of hypernuclei in the (e,e'K$^+$) reaction on light-to-medium mass targets. A time-of-flight system consisting of three scintillator planes (ToF) is part of the particle identification. To achieve the required accuracy, raw time measurements, TDC values, need to be corrected for cable offsets, pulseheight effects (slewing correction) and speed of propagation in the scintillator material. We developed a calibration procedure that analyzes covariances between different detectors to extract a system of linear equation. The latter is then solved by a matrix solver. The mathematical procedure and results achieved with this method will be presented. [Preview Abstract] |
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LA.00027: An active magnetic field compensation system for the HKS aerogel Cherenkov detectors Angel Nunez, Joerg Reinhold Three segmented aerogel Cerenkov detectors are employed in the Jefferson Lab High Resolution Kaon Spectrometer (HKS). Cerenkov light is detected with 5" PMTs. At the detector location a stray field from the magnet of $\sim$5 gauss significantly reduces the photoelectron collection efficiency of the PMTs, despite the use of magnetic shielding. Therefore, we propose to compensate the stray field with bucking coils. In a test setup, a Helmholtz Coil was used to generate external magnetic fields up to 15 gauss. In order to counteract this B field 20 turns of bucking coil (gauge: 12 AWG) were mounted around the cathode sides of the PMT. A recovery of roughly 87.5\% was determined for an external B field of 5 Gauss. The experimental procedure and results of both this and new studies on the installed detector will be presented in detail. [Preview Abstract] |
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LA.00028: The Jefferson Lab E05-115 Hypernuclear Spectroscopy Experiment Jason Bono, Joerg Reinhold Jefferson Lab experiment E05-115 will study hypernuclear excitation spectra in the reaction spectroscopy employing the (e,e'K$^+$) reaction. The goal is to improve the current accuracy for medium mass hypernuclei from $\approx$1-2 MeV to roughly 400 keV. This will improve the knowledge of the hyperon-nucleon interaction. The experiment employs a new spectrometer system consisting of high-resolution kaon and electron spectrometers (HKS \& HES) and the associated focal plane instrumentation. The experiment will run August through October 2009. The experimental apparatus and technique will be presented in detail, as well as any preliminary results. [Preview Abstract] |
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LA.00029: Intranight Optical Variability of 1418+546 H.G. Marine, H.R. Miller, J. Eggen, J. Maune, K. Marshall The object 1418+546 is a BL Lacertae object which is a member of a class of Active Galactic Nuclei (AGN) called blazers. Photometric observations of 1418+546 have been made in through an R-filter using the 16-inch Meade telescope at Hard Labor Creek Observatory (HLCO) and the 31-inch telescope at Lowell Observatory. Significant night-to-night variations have been observed with intranight optical variability superposed on these longer term variations. Preliminary analyses show the time scale of variability for this object is one of the shortest in its class. The timescale of the variations will place an upper limit on the size of the emitting region. This data set will also be investigated to determine if a there exists a characteristic timescale or periodicity in these variations. [Preview Abstract] |
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LA.00030: Photon diffraction John Hodge In current light models, a particle-like model of light is inconsistent with diffraction observations. A model of light is proposed wherein photon inferences are combined with the cosmological scalar potential model (SPM). That the photon is a surface with zero surface area in the travel direction is inferred from the Michelson-Morley experiment. That the photons in slits are mathematically treated as a linear antenna array (LAA) is inferred from the comparison of the transmission grating interference pattern and the single slit diffraction pattern. That photons induce a LAA wave into the plenum is inferred from the fractal model. Similarly, the component of the photon (the hod) is treated as a single antenna radiating a potential wave into the plenum. That photons are guided by action on the surface of the hod is inferred from the SPM. The plenum potential waves are a real field (not complex) that forms valleys, consistent with the pilot waves of the Bohm interpretation of quantum mechanics. Therefore, the Afshar experiment result is explained, supports Bohm, and falsifies Copenhagen. The papers may be viewed at http://web.citcom.net/$\sim$scjh/. [Preview Abstract] |
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LA.00031: The Proof of the ``Vortex Theory of Matter'' Konstantin Gridnev, Russell Moon, Victor Vasiliev According to the Vortex Theory, protons and electrons are three-dimensional holes connected by fourth-dimensional vortices. It was further theorized that when photons are absorbed then readmitted by atoms, the photon is absorbed into the proton, moves through the fourth-dimensional vortex, then reemerges back into three-dimensional space through the electron$^{2}$. To prove this hypothesis, an experiment was conducted using a hollow aluminum sphere containing a powerful permanent magnet suspended directly above a zinc plate. Ultraviolet light was then shined upon the zinc. The zinc emits electrons via the photoelectric effect that are attracted to the surface of the aluminum sphere. The sphere was removed from above the zinc plate and repositioned above a sensitive infrared digital camera in another room. The ball and camera were placed within a darkened box inside a Faraday cage. Light was shined upon the zinc plate and the picture taken by the camera was observed. When the light was turned on above the zinc plate in one room, the camera recorded increased light coming from the surface of the sphere within the other room; when the light was turned off, the intensity of the infrared light coming from the surface of the sphere was suddenly diminished. Five other tests were then performed to eliminate other possible explanations such as quantum-entangled electrons. [Preview Abstract] |
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LA.00032: Numerical Solution of Time-Dependent Gravitational Schr\"{o}dinger Equation Vic Christianto, Diego L. Rapoport, Florentin Smarandache In recent years, there are attempts to describe quantization of planetary distance based on time-independent gravitational Schr\"{o}dinger equation, including Rubcic {\&} Rubcic's method and also Nottale's Scale Relativity method. Nonetheless, there is no solution yet for time-dependent gravitational Schr\"{o}dinger equation (TDGSE). In the present paper, a numerical solution of time-dependent gravitational Schr\"{o}dinger equation is presented, apparently for the first time. This numerical solution leads to gravitational Bohr-radius, as expected. In the subsequent section, we also discuss plausible extension of this gravitational Schr\"{o}dinger equation to include the effect of phion condensate via Gross-Pitaevskii equation, as described recently by Moffat. Alternatively one can consider this condensate from the viewpoint of BogoliubovdeGennes theory, which can be approximated with coupled time-independent gravitational Schr\"{o}dinger equation. Further observation is of course recommended in order to refute or verify this proposition. [Preview Abstract] |
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LA.00033: Nuclear Transparency of Kaons F.N.U. Nuruzzaman Quantum Chromo Dynamics (QCD) is the fundamental theory of the strong force. The transition from nucleons and mesons to the quarks and gluons of QCD can be studied by looking for the onset of phenomena predicted by QCD, such as Color Transparency (CT). CT is the disappearance of final (initial) state interactions for hadrons produced in exclusive processes at high momentum transfers. An experiment to measure the transparency of pions, in search of CT was completed in Dec 2004 at JLab in Hall C. The same set of data also has a considerable sample of kaons that can be used to study the transparency of kaons. Kaon transparency via electro-production has not been studied before and will provide useful information regarding the nature of the transition from quarks to hadrons. In addition, this data will help us investigate the anomalous strangeness transparency reported for kaon nucleus scattering data. We will extract the kaon transparency by comparing the electro-production of kaons from various nuclear targets to electro-production from hydrogen which is similar to the technique used to measure pion transparency. [Preview Abstract] |
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LA.00034: A New Beam Modulation Strategy for Q$^{p}_{weak}$ Experiment F.N.U. Nuruzzaman A new, robust strategy is presented for beam modulation in the Q-weak experiment. The objective of the Q-weak experiment is to measure the weak charge of the proton by a measurement of the parity violating asymmetry ($<$ 1ppm) in elastic e-p scattering to determine the proton's weak charge with $\approx $ 4{\%} combined statistical and systematic errors. The e-p scattering rate depends on the five beam parameters: horizontal position (X), angle (X), vertical position (Y), angle (Y) and energy (E). Small changes in these parameters will create a change in rate which results as false asymmetry. We measure the detector sensitivities to correct remaining false asymmetry by keeping these parameters as small as possible. For detector sensitivity measurement, we will modulate X, X, Y, Y using four pairs of coils in the Hall-C (3C) beamline and energy using an SRF cavity. Two pairs of coils will be pulsed at a time to produce relatively pure position and angle changes at the target, for virtually any tune of the 3C line. We have determined the optimal positions for the coils that will be used to modulate the beam. These results and some preliminary tests of the coils and the associated control instrumentation are discussed. [Preview Abstract] |
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LA.00035: Effect of Weather Condition on the Muon Flux Distributions Olesya Sitnikova In recent years, many studies have been done regarding to the correlations between the Earth's climate conditions and the cosmic ray fluxes [1,2]. The Earth atmosphere is constantly bombarded by a rain of charged particles known as the primary cosmic rays. These primary cosmic rays will collide with the atmospheric molecules in the upper atmosphere and create extensive secondary particles which shower downward to the surface of the Earth. Most of the particles, which reach to the surface of the Earth, are muons ($>$80{\%}) together with a small percentage of electrons, gammas, neutrons, etc. The fluxes of these particles should be influenced by the weather conditions of the Earth's atmosphere, which can be regarded as particle radiation absorber. At Georgia State University (GSU), multiple cosmic ray particle detectors have been constructed to measure the fluxes and energy distributions of the secondary cosmic ray particles. In this presentation, I will describe the setup of one of the muon detectors at GSU. The detector has been recording data nonstop since July of 2009. The preliminary results of the correlation study of the muon flux with the atmospheric temperature, pressure and solar radiation will also be discussed in this presentation. Reference: 1) L.V. Egorova, V. Ya Vovk, O.A. Troshichev, Journal of Atmospheric and Terrestrial Physics 62, 955-966 (2000). 2) Henrik Svensmark, Phy. Rev. Lett. 81, 5027 (1998). [Preview Abstract] |
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LA.00036: Two-dimensional Yang-Mills on a single site lattice David Mayett, Ari Hietanen, Fajamani Narayanan In this work, we analyzed the chiral condensate in two dimensions for Yang-Mills theory coupled to adjoint fermions. We perform simulations on a single site lattice. Since the center symmetry is not broken, the theory is in the confined phase. Chiral symmetry is expected to be broken in the confined phase and we compute the value of the chiral condensate. [Preview Abstract] |
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LA.00037: Investigation of Biological Adhesives and Polyurea Crosslinked Silica-Based Aerogels Laura Lyons, Meagan Cauble, Judith Cole, Firouzeh Sabri One of the key steps towards developing new technology for nerve repair is to look at the interaction mechanism and strength of biological components with the material under investigation. The existing technology for peripheral nerve repair relies on suturing techniques for attaching and immobilization of the implant. It is also limited to connecting two nerve components only, through a cylindrical-shaped unit which we will refer to as 1-D. The focus of our work is to develop an aerogel-based printed circuit board (PCB) system for precise guidance of multiple (n-D) neuronal components, simultaneously. Here we report on the adhesion strength of sciatic nerve segments removed from cadaver Sprague Dawley rats and the surface of treated and untreated polyurea cross-linked silica-based aerogels. The adhesion strength of the nerve to the aerogel surface was studied under varying environmental conditions as well as surface coating types. The coatings tested were basement membrane extract (BME), Cell Tak, and the combination. Since the mechanism of adhesion to cells and other surfaces is different and non-competing for BME and Cell Tak it is expected that a stronger adhesion should be accomplished by combining these two adhesives. The effect of temperature, nerve elasticity, and ionic concentration on the strength of adhesion was investigated also and will be reported. [Preview Abstract] |
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LA.00038: Nero Zero Frequency Sounding in Layered Media Chastity Autry, Alexandru Tamasan, Johann Veras We consider the mathematical model of frequency sounding of a continuously layered media. By the means of frequency asymptotic expansion of the wave field, this problem is equivalent to an inverse boundary value problem for the Ricatti equation. We solve the inverse Ricatti problem via a Cauchy problem for a first order quadratic equation for sequence-valued maps. The quadratic equation contains no unknown coefficients. The information of the medium is encoded in the initial value. For specific data, the Cauchy problem has a unique solution. Based on the contraction mapping principle the method of proof provides a stable reconstruction algorithm. The computational feasibility of the proposed approach is demonstrated in a numerical experiment. [Preview Abstract] |
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