Bulletin of the American Physical Society
81st Annual Meeting of the APS Southeastern Section
Volume 59, Number 18
Wednesday–Saturday, November 12–15, 2014; Columbia, South Carolina
Session JP: Poster Session |
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Room: Poster Hall |
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JP.00001: Monte Carlo Simulation of a Micro-Nuclear Battery Benjamin Guthrie, Phillip Womble, Keith Andrew Betavoltaics are beta decay-powered batteries that could potentially last for decades, but direct radiation damages the semiconductors of a battery long before its potential lifetime is over. Photon Assisted Radioisotopic Energy Source (PARES) batteries use a phosphorescent scintillator to convert radiation to photons which then impinge on a photovoltaic, which, in essence, shields the photovoltaic from the ionizing radiation. As part of an on-going research project, we plan to perform a survey of optimal fuel/scintillator/photovoltaic combinations. A Monte Carlo simulation code was developed to simulate the radioactive decay of the fuel, its subsequent interaction with the scintillator, the emission and absorption of photons from scintillation and the resulting potential differences in the photovoltaic. Two radioisotopes, Ni-63 and Sm-151, were selected as potential fuels and subsequently modeled. The calculations indicate that Ni-63 would deposit 1.23 $+$/- 0.2 times as much energy in the scintillator as Sm-151 did. The simulation was then benchmarked against the Monte Carlo N-Particle (MCNP) transport code. Our initial results indicate that our code can serve as a reliable platform for simulating the photovoltaic cells of the PARES battery in future research. [Preview Abstract] |
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JP.00002: A Wave Equation Cyber Model for Tracking Ebola from Data Mining African Tweets Armin Smailhodzic, Keith Andrew, Eric Steinfelds, Lance Hahn, Phil Womble, Cathleen Webb We are tracking the spread of Ebola in Africa via data mining of active Twitter accounts. Using a meme based n-gram semantic usage model we search the Twitter database for indications of illness, flight and death from the spread of Ebola in Africa, principally from Guinea, Sierra Leone and Liberia. Memes of interest relate disease to location and severity and are coupled to the density of Tweets and re-Tweets. The meme spreads through the community of social users in a fashion similar to nonlinear wave propagation- like a shock wave, visualized as a spike in Tweet activity. We model the spreading as a system isomorphic to a modified SIR (Susceptible, Infected, Removed disease model) system of three coupled nonlinear differential equations using Twitter variables. The nonlinear terms in this model lead to feedback mechanisms that result in unusual behavior that does not always reduce the spread of the disease. The resulting geographic Tweet densities are coupled to geographic maps of the region. These maps have specific threat levels that are ported to an App and can be used by travelers to assess the relative safety of the region they will be in. [Preview Abstract] |
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JP.00003: Surface Microstructure Evolution of Metallic Specimens Using the Large Chamber Scanning Electron Microscope Grace Egbujor, Edward Kintzel An initial study into the use of the large chamber scanning electron microscope (LC-SEM) to interrogate the surface microstructure evolution of metallic specimens has been carried out. The LC-SEM located at Western Kentucky University is the largest instrument of its type at any university in the world. As such, unique measurements can be performed due to the size of its chamber and extended view of its optic system. Strain was varied for each individual specimen, and imaged using Backscattered Electrons within the gauge length as well as near the grip position. Results will show the relationship between time to failure and nickel content of metallic specimens. Additionally, results will demonstrate the capability of the LC-SEM to carry out these types of measurements. Future measurements will include the incorporation of a in-situ uniaxial load frame for dynamic studies. [Preview Abstract] |
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JP.00004: Semi-analytical and Compactable Results for Cylindrically Symmetrical Capsules and ``Diconoids'' and their Corresponding Number Crunched Simulations Eric Steinfelds, Keith Andrew Our poster demonstrates the success of a Hybrid Algorithm of Greens functions and FEM computations in calculating the $\gamma$,n-currents and scalar fluxes of X-rays or n's which come from isotopes which are located either on or inside of the exotic shapes of cigars and ``diconoids.'' This Hybrid Algorithm also can predict the electric fields from ions or e's stored in such shapes. In ``Classical Electrodynamics'' by JD Jackson, treatment is given to electric fields which emanate from nonrandomly distributed charges within or on spheres and cylinders. However, little attention is given to determining the electric field which results from the distribution of electric charges within shapes such as the cyl-symmetrical cigar or the ``diconoid.'' The diconoid is defined as 2 opposing cones which are intersected by the common disk/edge. To a reasonable approximation, a diconoid shape or 3-D surface can be enclosed by a square dipyramid or to even better approximation by an octagonal dipyramid. See wolfram.com/SquareDipyramid.html for a fitting image. This poster shows advanced analytical calculations and semianalytical computations assisted by an FEM algorithmic modules with applications in shielding calculations, dosimetry, and micro-scale electrostatics. [Preview Abstract] |
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JP.00005: Monochromatic Micro-X-Ray Fluorescence to Measure Accumulations of Iron in the Spleens of Methamphetamine-Doped Mice Amanda Kennell, Anela Camdzic, Hayley Adams, Sarah Formica A monochromatic, micro-X-ray Fluorescence Spectroscopy (M$\mu $XRF) system is used to measure iron concentrations in spleens of methamphetamine-doped mice to quantify the physiological phenomenon that methamphetamine overexposure causes an accumulation of iron in the spleen. Qualitative measurements have already confirmed this phenomenon, however the XRF results will quantify these measurements quickly, inexpensively, and without destroying the spleen samples. This technique of heavy metal detection will be used in future experiments to determine iron and other metal concentrations in various biological tissues, such as brain tissue. The XRF system comprises a low-power (50 W), Rh-target sealed tube source, a Doubly-Curved Crystal (DCC) optic, and a Si-PiN diode detector. The coupling of the DCC optic with the low-power source allows for an intense, monochromatic, 200-$\mu $m-diameter focal spot without the need for water-cooling or a rotating anode source. [Preview Abstract] |
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JP.00006: Monochromatic Micro-X-Ray Fluorescence to Detect Heavy Metal Particulates on Spider Webs as a Measure of Air Quality Anela Camdzic, Amanda Kennell, Hayley Adams, Michael Bodri, Sarah Formica A monochromatic, micro-X-ray Fluorescence Spectroscopy (M$\mu $XRF) system is used to analyze spider webs to detect metal particulates that are commonly found in polluted air and automobile exhaust. Spider webs are collected from areas of varying air quality with those from the most-polluted regions showing higher concentrations of heavy metals, which include Fe, Zn, Co, Mg, Pt, and Pb. The XRF system comprises a low-power (50 W), Rh-target sealed tube source, a Doubly-Curved Crystal (DCC) optic, and a Si-PiN diode detector. The coupling of the DCC optic with the low-power source allows for an intense, monochromatic, 200-$\mu $m-diameter focal spot without the need for water-cooling or a rotating anode source. [Preview Abstract] |
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JP.00007: Towards a Robust Model of Eastern U.S. Crustal Structure and Composition for Applications in Seismic Hazard Analysis Pranav Arrepu, Cemal Biryol While large-scale studies to obtain crustal parameters and structure have been performed on various regions within North America, detailed receiver function (RF) studies to resolve the structure above the Moho have only been recently performed for the Eastern U.S. Our work retrieves various crustal parameters and receiver-side structure as results of RF analysis for a data two selected stations in North Carolina. Results from 52 RFs indicate a crustal thickness of $\sim$ 36.2 km and a V$_{\mathrm{p}}$/V$_{\mathrm{s}}$ ratio of $\sim$ 1.51 for the receiver structure beneath TA.V57A as well as a crustal thickness of $\sim$ 27.7 km and a V$_{\mathrm{p}}$/V$_{\mathrm{s}}$ ratio of $\sim$ 1.68 for the receiver structure beneath TA.V58A. These parameters are used to create crustal models that are perturbed via 1D inversion. A parameter space search method is developed as means for obtaining robust results in a computationally inexpensive manner. Initial forward modeling and inversion results suggest a shallow depth layer of high velocity above the Moho and may support the eastward extent of basement rocks associated with Grenville Orogeny. We use a shear wave velocity model obtained from our study to determine ground shaking parameters for the Eastern U.S. Along with demonstration of robust results for crustal structure and ground shaking, we propose strategies to expand our data set for the Eastern U.S and assessment of ground shaking for a wider region. [Preview Abstract] |
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JP.00008: Integrated Flight Computer for a High Altitude Balloon Dominic Critchlow, Bryan Gaither, Justin Oelgoetz Integrating a number of pieces of scientific equipment for in flight use on a stratospheric balloon requires a common flight computer. This is especially important if one wants to tie data from sensors such as an accelerometer, magnetometer, and GPS to a piece of equipment such as a Geiger counter. We are designing and building an integrated flight computer that combines flight sensors, and can be used to collect data from other systems based around the Arduino microcontroller. The system logs data for altitude, pressure, and temperature as well as a 3 axis magnetometer and a 3 axis accelerometer to record forces on the payload. GPS data is also being recorded to match the data that is acquired to a specific location. The system is expandable to record data from other devices (such as a Geiger counters) and to control external hardware (such as a camera or sample collector). Results from system testing will be presented. [Preview Abstract] |
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JP.00009: A System of coupled ODEs as a Cyber Model for Analyzing Wavelike Information Transmission from Data Mining Tweets Morgan Taylor, Armin Smailhodzic, Keith Andrew, Lance Hahn, Phil Womble, Cathleen Webb, Blair Thompson We are tracking social events such as the spread of Chikungunya, the activity of a school related shooting or an active crowd surge similar to the Hong-Kong political unrest via data mining of active Twitter accounts. Using selected word memes we search the Twitter database for indications of activity, illness, and travel as indicators of possible life altering events such as the spread of a virus. Memes of interest relate activity to location and spreading which are coupled to the density of Tweets and re-Tweets. The meme spreads through the community of social users in a fashion similar to nonlinear wave propagation- like a soliton, visualized as a moving spike in Tweet activity. We model the spreading of the virus as a system of ODEs isomorphic to a modified Tweet-Erase-Retweet (TER) system of three coupled nonlinear differential equations using Twitter variables. Numerical methods are used in Mathematica to generate solutions to the system for regions of interest. The nonlinear terms in this model lead to feedback mechanisms that result in unusual behavior that can lead to Retweet growth. [Preview Abstract] |
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JP.00010: Temperatures and Densities of Planetary Nebulae from Optical Spectra Benjamin Riley, Ting-Hui Lee, Richard Shaw, Letizia Stanghellini We present preliminary results from an optical spectroscopic survey of compact planetary nebulae (PNe) in the Galactic disk. PNe are the envelopes ejected by Sun-like stars near the end of their lives. This is an ongoing optical$+$infrared spectral survey of 150 compact PNe to build a complete database of PN chemical abundances in the Galactic disk. We obtained optical spectra of 12 PNe with the Southern Astrophysical Research (SOAR) Telescope in February 2013. The flux intensities of the emission lines H-alpha, H-beta, [OIII], [NII], [SII], and [ArIV] are measured and reddening corrected. Here we present the physical diagnostics such as electron temperature and density for each PN derived from the reddening-corrected line intensities. We will use these diagnostics to derive the elemental abundance of He, N, O Ne, S and Ar in subsequent analyses. [Preview Abstract] |
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JP.00011: Topological Deformations and the Homotopic Analysis Method Applied to a NLPDE Blazar Jet Model Mitchell Harmon, Keith Andrew, Eric Steinfelds, Michael Carini We use a method of topological deformation to explore solving nonlinear partial differential equations as developed by Liao. In general the tools of algebraic topology, such as homotopic mapping, can be used to study topological spaces that can be continuously deformed into each other while keeping all topological quantities invariant such as continuity, dimension, connectedness and orientation. By introducing a homotopic deformation parameter one can use homotpic maps to solve a large class nonlinear differential equations. As a result of the mapping a single nonlinear partial differential equation can be converted into an infinite system of linear ordinary differential equations of higher order in the deformation parameter, thereby producing ODEs of different deformation order. These equations are then solved using a Maclaurin deformation series method. Here we apply this technique, the Homotopy Analysis Method, to a NLPDE that appears in certain Blazar jet models and explore the convergence properties of the solutions. [Preview Abstract] |
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JP.00012: Synthetic Photometry of White Dwarf Candidates for Calibration of the Dark Energy Survey Mees Fix, Allyn Smith, Douglas Tucker, William Wester, Pier-Emmanuel Tremblay, Severin Charbonnier The Dark Energy Survey (DES) is a current project in Fermilab's Cosmic Frontier program. It is a 5000-square-degree optical/near infrared imaging survey conducted over five years (2013-2018) for purposes of constraining the properties of dark energy. Photometric calibration of the DES is approached as a two part process. First is the Global Relative photometry effort to tie the survey in a seamless manner across the footprint. The second part of the effort is the Absolute photometry program which will set the zeropoints for each of the survey filters ($grizY$). Synthetic photometry of pure-hydrogen-atmosphere ``DA'' white dwarfs is currently the preferred technique for absolute zeropoint calibration of large sky surveys. For absolute calibration of the DES we are developing a ``Golden Sample'' of 30-100 DA white dwarfs, drawn from an initial sample of nearly 1000 candidate white dwarfs in the DES footprint. First, a spectroscopic observational campaign is needed to begin this process to verify spectral types and obtain synthetic magnitudes. The synthetic magnitudes will then be used to determine the filter zeropoints. [Preview Abstract] |
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JP.00013: ARISE Sydney Toney, Jeffery Secrest A supernova is one of the most catastrophic events to occur in our universe. When a core collapse supernova occurs, an enormous burst of neutrinos of all flavors is released. A number of neutrino experiments (such as the Helium And Lead Observatory (HALO) and the next generation Sudbury Neutrino Observatory (SNO+)) are capable of detecting these supernova neutrinos generated within our galactic neighborhood. The observation of supernova neutrinos may provide insight into the mechanisms for a core collapse supernovae and properties of neutrinos. This poster will focus on the development of a supernova Monte Carlo that can be used to study the supernova neutrino signal in a neutrino detector. [Preview Abstract] |
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JP.00014: Numerical Simulations of Granular Asteroid Growth Benjamin Beaumont It is believed that planetesimals and asteroids are created by the accumulation of interstellar dust. However, the processes that govern the collision, agglomeration, and fragmentation of clusters of grains are not well understood. Prior research in the topic has established regimes for the results of conservative collisions of particle clusters held together by contact forces, but neglects gravity, a critical component once particles are no longer touching. We run simulations of clusters of particles modeled as hard frictionless spheres that take into account gravity and dissipation of energy. We obtain outcomes of collisions of two clusters with variable masses, particle counts, velocities, and impact parameters. We then compare our results to other models and simulations, and find that conservative collisions can take place at higher energies than classically predicted. [Preview Abstract] |
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JP.00015: Replicating Stellar Transit Phenomena Dorothy Dickson-Vandervelde, Ryan Brown, Jeannette Myers Exoplanet discovery by the method of observing transit events is one primary method used by astronomers today. The challenge of explaining the phenomena to young people by means of a physical system that can be modified by the user was the goal of this project. An Orrery was constructed using only materials readily available. Variations in planet size, light source, and observing annulus size were explored and transit light curves were obtained. Results of stability analysis and comparison to stellar transit data are presented. This work was supported by NASA Grant NNX13AD05G. [Preview Abstract] |
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JP.00016: Searching for Variable Stars in the DES Tertiary Standard Star Fields Samuel Wyatt, Douglas Tucker The Dark Energy Survey (DES) is a 5000 deg$^{2}$ grizY imaging survey to be conducted using a proposed 3 deg$^{2}$ wide-field mosaic camera on the CTIO Blanco 4-m telescope. The primary scientific goal of the DES is to constrain dark energy cosmological parameters via four complementary methods: Galaxy Cluster Counting, Weak Gravitational Lensing, Baryon Acoustic Oscillations, and Type Ia Supernovae, supported by precision photometric redshifts. We present background on the DES and Tertiary Standard star fields used in the survey, methods for searching for Variable Stars, and the results received from the search. [Preview Abstract] |
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JP.00017: Minimizing Residual Pressure within a Windowless Gas Target System - JENSA Orlando Gomez, Justin Browne, Fernando Montes, Kontos Antonios, Hendrik Schatz Nuclear reactions between light gases and radioactive isotope beams are essential to address open questions in nuclear structure and astrophysics. Pure light gas targets are critical for the measurements of proton- and alpha-induced reactions. \underline {J}et \underline {E}xperiments in \underline {N}uclear \underline {S}tructure and \underline {A}strophysics (JENSA) is the world's most dense ($\sim$10$^{19}$ atoms/cm$^{2}$) windowless gas target system. Most of the gas flow is localized; however, escaping gas creates a pressure gradient which degrades experimental measurements and contaminates the beam line. JENSA contains a differential pumping system to maintain a vacuum. The previous design configuration was not optimized for experiments (pressure measurements 70 cm downstream from the jet were $\sim$10$^{-3}$ torr; optimal is less than 10$^{-4}$ torr). We have altered the current differential pumping system to minimize the residual pressure profile. Several configurations of two gas-receiving catchers were tested, and the most efficient ones identified using Enhanced Pirani and Cold Cathode gauges. We have determined the 30 mm outer and 20 mm inner gas-receiving cones minimize JENSA central chamber pressure to 200 millitorr at 16,000 torr of discharge pressure. Altering the tubing configuration has additionally lowered the pressure 70 cm downstream to 10$^{-5}$ torr. The new residual pressure allows operation of JENSA with planned expansion of a recoil mass separator SECAR. [Preview Abstract] |
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JP.00018: Low Temperature Chemistry with Trapped Ions Kevin Ferri, Ed Bell, Joan Marler At temperatures 5 orders of magnitude less than room temperature individual ions and ensembles of ions can be studied and manipulated with an unprecedented level of control. To achieve these temperatures ions are isolated in an rf-trap and laser-cooled to temperatures in which their internal states can be measured, set and switched at the individual ion level. Since the earliest days of ion trapping, scientists have appropriated these traps to perform experiments in fields as diverse as fundamental particle physics, anti-matter science, quantum information science, condensed matter, and chemistry. At Clemson near term experiments include following state to state chemical reactions, studying chemistry relevant to astrophysical systems and performing highly accurate measurements of carbon containing organic systems. Additional experiments will explore beyond the standard model physics using Highly Charged Ions (HCIs) from the Clemson EBIT which have been subsequently trapped in an ion trap. [Preview Abstract] |
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JP.00019: Electric-Field-Induced Second-Harmonic Generation in Serrated Nanogap Arrays Anna Yanchenko, Roderick Davidson II, Jed Ziegler, Robert Marvel, Sergey Avanesyan, Richard Haglund Jr. Asymmetric plasmonic nanoparticles can be used to generate and control the spatial distribution of electric fields at the nanoscale in order to efficiently generate second-harmonic light and control its polarization response. Electric-field-induced second-harmonic generation (EFISH) allows for the optical modulation of second-harmonic light using an external, applied electric field. In our experiments, we fabricated novel asymmetric gold nanogaps and demonstrated that they produced second-harmonic light with a conversion efficiency on the order of 10$^{-11}$. Three plasmonic geometries were fabricated to create unique electric field gradients on a length scale of the order of 100nm. Finite-difference time-domain (FDTD) simulations and experimental extinction spectra of the nanogaps were performed, and the nanogaps were found to have broad plasmonic resonances at 800nm. The plasmons were excited with a horizontally polarized ultrafast Ti:Sapphire laser at 800nm. PMMA was then deposited into the nanogaps, and we found that the PMMA red-shifted the plasmon resonance and reduced the SHG conversion efficiency due to absorption by the PMMA. Future experiments are planned with additional centrosymmetric, non-centrosymmetric and ferroelectric materials. [Preview Abstract] |
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JP.00020: Spectroscopy of Vibrational States in Diatomic Nitrogen Molecules Mary Mulholland, Charles Harrill, Sethfield Smith This project is focused on understanding the vibrational structure of nitrogen, which is a homonuclear diatomic molecule. A 5000V AC discharge will be used to selectively excite neutral nitrogen molecules to a particular electronic state. By performing spectroscopy on the electronic transitions from this state to a lower electronic state, the data should only show those vibrational bands which connect the two electronic states. Assuming that a number of vibrational levels are populated in the higher energy electronic state, the electronic transitions to all of the allowed vibrational levels in the lower energy electronic state should provide sufficient data to determine the vibrational structure of both states. Emission spectra will be collected with a Thorlabs CCS200 Compact Spectrometer. The spectrometer has a range of 200-1000 nm with a resolution of less than 2 nm and is sensitive enough to resolve the vibrational states in diatomic nitrogen molecules. The results will be compared to a simple harmonic oscillator model. [Preview Abstract] |
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JP.00021: Using Quantum Optics to Prove the Existence of Photons Preston Alexander, Scott Baldwin, S. Blane McCracken, R. Seth Smith During the past two years, a Quantum Optics Laboratory was constructed and tested at Francis Marion University. A spontaneous parametric downconversion source was used to create pairs of correlated photons for use in single photon tests of quantum mechanics. In this experiment, the existence of photons was proven by using a spontaneous parametric downconversion source and a three-detector measurement setup. The two beams emanating from the downconversion crystal are referred to as the signal and idler beams. Detector A was placed in front the idler beam. The signal beam was sent to a 50/50 beam splitter, in which the reflected beam was sent to detector B and the transmitted beam was sent to detector B$'$. If photons exist, then these quanta of light energy are indivisible and can only be reflected or transmitted by the beam splitter, but not both. In other words, a photon cannot be divided into two equal halves by the beam splitter. If a simultaneous pair of downconverted photons can only be detected by detector A and either detector B or detector B$'$, but not both, this means that the photon could not be divided. The details of the experimental setup and the results will be presented. [Preview Abstract] |
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JP.00022: Modeling the black intermediate formed in the cathode of Vanadium redox flow batteries Laura Judy, Justin Oelgoetz There has been much research done into creating a battery that can hold charge indefinitely with little waste and scale to large industrial and even electric grid installations. One particular battery that has proven to be a viable candidate for low-waste, high-energy storage is the vanadium redox flow battery. As the battery discharges, VO$^{\mathrm{2+\thinspace }}$is reduced to VO$_{\mathrm{2}}^{\mathrm{+}}$ at the positive electrode and V$^{\mathrm{2+}}$ is oxidized to V$^{\mathrm{3+}}$ at the negative electrode. The process is reversed as the battery is charged. During this process, the reactions cause the solutions to change colors -- turning from yellow to blue at the cathode and violet to green at the anode. In addition to the color change of the solutions, there is a black intermediate that forms during partial discharge at the cathode that has been hypothesized to be V$_{\mathrm{2}}$O$_{\mathrm{3}}^{\mathrm{3+}}$. This poster presents results of semi-empirical methods (PM6 and PM7) models which aim to identify the black intermediate. We will present not only thermo-chemical results but also the predicted vibrational structure and the RAMAN lines. [Preview Abstract] |
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JP.00023: Atomic Masses of Tritium and Helium-3 Bridget Wesson, Anke Wagner, Holger Kracke, Edmund Myers By measuring the cyclotron frequency ratios of $^{3}$He$^{+}$ to HD$^{+}$ and T$^{+}$ to HD$^{+}$, and using HD$^{+}$ as a mass reference, we obtain new atomic masses for $^{3}$He and T. Our results are M[$^{3}$He] $=$ 3.016 029 322 43(19) u and M[T] $=$ 3.016 049 281 78(19) u, where the uncertainty includes an uncertainty of 0.12 nu in the mass reference. Allowing for cancellation of common systematic errors, we find the Q-value for tritium beta-decay to be (M[T] -- M[$^{3}$He])$c^{2} = $ 18 592.01(7) eV. This allows an improved test of systematics in measurements of tritium beta-decay that set limits on neutrino mass. [Preview Abstract] |
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JP.00024: Laser Photodetachment Spectroscopy of the S$_{2}^{-}$ Anion Colin Tyznik, John Yukich In this experiment, low-resolution photodetachment spectroscopy of the S$_{2}^{-}$ anion was conducted over photon energies in the range of the S$_{2}$ electron affinity. The S$_{2}^{-}$ anions are created by a dissociative attachment process. These ions are then stored in a Penning ion trap, and are bombarded by photons of varying energies generated by a tunable, titanium sapphire laser. This results in photodetachment. The ions are counted before and after bombardment, allowing the effect of different photon energies to be observed on the overall detachment probability. The results show structure that could be due to vibrational energy levels, and that may indicate the electron affinity of the molecule. Future experiments will examine more closely the vibrational structure in the photodetachment caused by the different photon energies. [Preview Abstract] |
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JP.00025: Modeling Amorphous Materials via Randomly Generated Networks Samuel Cupp, Justin Oelgoetz Materials research today relies heavily on experimental research to drive the discovery of new materials. Theoretical work is used to explain properties and interpret experimental data but is far less commonly used as a predictive tool. In covalent glass/amorphous materials research, the input to these calculations is often an initial structure formed based off experimental data. The major hindrance to performing theoretical calculations is the time-consuming task of manually adjusting the amorphous network, which is used as initial starting points for geometric optimizations. For purely computational approaches to make predictions, the process of producing amorphous networks must be automated. We previously implemented a Monte Carlo approach to create amorphous networks from constituent atoms and used the Metropolis algorithm to determine characterizations of these networks. We use MOPAC to calculate energies and physical properties. We are currently enhancing our program to use the Cation-Interlinking Network Cluster Approach and have implemented a method for randomly generating a glassy network built from base fragments. We calculate the pairwise distribution functions and average energy for these networks by averaging over MOPAC-optimized random networks. Our next steps are to fully implement the Metropolis method for CINCA and investigate differences in runtime and accuracy between the old and new methods. [Preview Abstract] |
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JP.00026: A Theoretical Study of The Coupling Between Chemical Equilibrium and Physical Interactions That Determine Self-Organization in End-Grafted Polyelectrolytes for Tissue-Material Applications Ebtisam Aldaais, Mark Uline Understanding the competition of interactions in highly inhomogeneous environments such as those relevant in tissue engineering nanotechnology, and those responsible for biological cell function is critical to the further development of design platforms for such systems. We use a three dimensional mean-field theory to study the competition between electrostatic, van der Waals and steric interactions in determining the molecular organization of end-grafted polyacids. The polyelectrolyte layers spontaneously form self-assembled aggregates whose morphologies are manipulated by the composition of the solution in contact with the film. These theoretical calculations show that chemical equilibrium and the relevant physical interactions present in responsive polymer layers couple in a highly non-additive manner. We find that charge regulation stabilizes micellar domains over a wide range of pH by reducing the local charge in the aggregate at the cost of chemical free energy and gaining in the van der Waals attractive interactions. The balance of interactions in this highly inhomogeneous environment determines the boundaries between different aggregate morphologies. We predict the formation of domains based on the proper choice of solution pH and salt concentration, and one can use these predictions to provide design guidelines for the creation of responsive polymer layers presenting self-organized patterns with the desired functional properties. [Preview Abstract] |
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JP.00027: Interaction of BSA proteins with 45S5 bioactive glass surface Zachary Pigott, Joe Harms, Roman Golovchak, Himanshu Jain Recent advances in bioscaffold engineering reveal a significant role of intermediate proteins layer adsorbed at the surface of bioscaffoldsintroduced into the body fluid. The adsorbed protein layer modifies host responses, such as platelet activation, coagulation and immune responses as well asother interactions between cells and biomaterial. In the present studies we report the first results on the X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy studies of bovine serum albumin (BSA) attachment to the surface of 45S5 bioglass prepared by different fabrication steps. It is shown by XPS that the amount of BSA attached to the surface depends strongly on Ca and P concentration. Thus Ca$^{+}$ and PO$^{-}$ could be identified as main protein binding sites on 45S5 bioglass surface. Conformations of BSA proteins adsorbed on the surface of 45S5 bioglass were studied by Raman microscopy. The Raman shift ofBSA protein layer attached to the surfaces of 45S5 bioglass is found to be different for the glasses ofdifferent structures(e.g. type and degree of phase separation) and from the Raman shift of BSA-attached bioinert surfaces. The observed difference is considered as a signature of different conformation of protein molecules related to the bioactivity of a particular surface. [Preview Abstract] |
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JP.00028: Effect of fullerenol surface chemistry on nanoparticle binding-induced protein misfolding Slaven Radic, Praveen Nedumpully-Govindan, Ran Chen, Emppu Salonen, Jared Brown, Pu Chun Ke, Feng Ding Fullerene and its derivatives with different surface chemistry have great potential in biomedical applications. In this study we focus on the effect of hydroxylation - a common strategy for solubilizing and functionalizing these carbon-based nanoparticles - on protein-nanoparticle interactions using a model protein, ubiquitin. We used set of complimentary modeling methods, including docking and molecular dynamics simulations. We found that all derivatives bound to the model protein, but the more hydrophilic nanoparticles with higher number of OH groups bind to the protein surface, stabilizing it, while more hydrophobic ones induced large conformational changes, causing protein denaturation. [Preview Abstract] |
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JP.00029: Critical current density and ferromagnetic loss in Ni-W substrates based coated conductors S.B. Harris, A.O. Ijaduola, C.L.H. Thieme, M.W. Rupich, A. Goyal One of the main challenges in the use of high temperature superconducting wires, the YBa$_{2}$Cu$_{3}$O$_{7-\delta}$(YBCO) coated conductors (CC) in electric power applications is the amount of dissipation or loss. Ni-W alloys are used as substrates for rolling assisted biaxially textured substrate (RABiTS) tapes because of their comparably low loss and ease of manufacturing. In this work, we have determined the amount of ferromagnetic loss in a series of biaxially textured Ni$_{\mathrm{1-x}}$W$_{\mathrm{x}}$ materials with compositions x $=$ 5 and 9 at.{\%} W. We also measured the critical current density $J_{c}$ in two different samples of coated conductor; one fabricated with the Ni-5at.{\%}W substrate and the other with the Ni-9at.{\%}W substrate. The aim is to determine if the type of substrate used will influence the amount and the property of $J_{c}$ measured. While the Ni-5at.{\%}W shows a higher ferromagnetism (and loss), the $J_{c}$ measured in both CC is fairly similar. The field and temperature dependence of the $J_{c} $ in the two samples is also analyzed. [Preview Abstract] |
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JP.00030: $T_{c}$ and Upper Critical Field Slopes of Nb/Cr Bilayers Amy Davis, Phillip Broussard We studied various superconducting properties of SC/AF bilayer films using Nb and Cr, observing the changes as the thicknesses of each metal was varied (Nb was held at 51 nm as Cr ranged from 5 to 100 nm, Cr was held at 50 nm as Nb was varied from 5 to 125 nm). These were grown by DC magnetron sputtering onto (100) oriented Si substrates. The samples were then attached to wires and cooled in a different vacuum chamber to $\approx$ 6 K, where we measured their critical temperatures ($T_c$) and perpendicular critical fields ($B_{c2}$) at low field strenghs ranging from 0 to $\approx$ 450 mT. We will compare our findings to the proximity effect theory for the $T_c$ and $B_{c2}$ of thin film bilayers. [Preview Abstract] |
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JP.00031: Crystallization kinetics of novel multifunctional glasses for IR photonics Leo Saturday, Roman Holovchak, Cameron Johnson, Yaroslav Shpotyuk Chalcogenide glasses (ChG) are an efficient medium for applications in modern photonics: combining high IR transparency, excellent fiber-drawing capability, and the largest optical nonlinearities reported to date. Nanomodifications of ChG could open the possibility of designing hybrid-materials, combining two or more useful properties in one functional medium. In this regard, several elements are found to modify ChG at the nanoscale. Rare-earth dopants are able to enhance the properties of ChG, allowing for applications as an active medium for optical sensors, lasers, optical amplifiers, and broad band sources in the mid-IR spectral range. In this work, we report thermal stability and crystallization kinetics studies for glasses of the Bi$_{\mathrm{x}}$Ga$_{\mathrm{y}}$(GeSe$_{4})_{\mathrm{50-(x+y)/2}}$(GeTe$_{4})_{\mathrm{50-(x+y)/2}}$ family, which are anticipated to be used as a host matrix with the potential to combine multiple features in one medium. Crystallization of at least three different phases is identified using differential scanning calorimetry (DSC). The Dietzel criterion of glass stability is determined, and the activation energies for each crystallization process are calculated. The applicability of the Johnson-Mehl-Avrami (JMA) relation to describe the crystallization kinetics is verified using J. Malek's approach. [Preview Abstract] |
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JP.00032: Recombination modeling for GaAs solar cells Keyuan Zhou, Tim Gfroerer, Yong Zhang Solar cells convert sunlight into electricity, but defects in the device can inhibit the conversion efficiency. Defects allow for the recombination of charge carriers, so they fail to contribute to the electrical output. Prior measurements and preliminary analysis reveal illumination and temperature-dependent trends in GaAs that help clarify the role of defects in this material. The aim of this project is to develop a more complete and self-consistent way to analyze the data. In particular, we seek to improve the physical model describing the recombination process in the presence of defects in GaAs. [Preview Abstract] |
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JP.00033: Photoexcitation energy transfer enhancement through atomic ligand exchange in a novel graphene-colloidal quantum dot interface Alexander Li The photonic applications of graphene are limited by its optical transparency and short exciton lifetime. To address this, colloidal quantum dots (CQDs) have been employed as light sensitizers from which photoexcited electrons can be transferred to graphene. Thus, recent research has been conducted on graphene-CQD interfaces (GCIs), which consist of CQD layers deposited on monolayer or few-layer graphene. However, the efficiency of photoinduced energy transfer at GCIs requires improvement. Using a theoretical model, we predicted that decreased CQD-graphene separation distance and lower CQD emission energies would result in unprecedented energy transfer rates. We therefore fabricated a novel PbS-based GCI employing atomic ligand passivation. PbS was chosen as the CQD material because we expected it to allow for faster energy transfer and more solar light absorption than current CdSe-based GCIs. The ligand exchange was performed to facilitate energy transfer by reducing CQD-graphene separation distance and improving CQD-graphene adhesion. Following the exchange, we observed an up to fivefold increase in energy transfer rate, thus verifying our theoretical predictions. Our findings are an important step in the development of GCIs for applications in optoelectronics. [Preview Abstract] |
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JP.00034: Treatment of electronic photomobilities at a Si(111) nanostructured surface with adsorbed Ag clusters using electronic band structure Robert Hembree, Tijo Vazhappilly, David Micha We report on a new treatment for computing the mobilities of photoexcited particles at Si(111) surfaces both with and without adsorbed Ag clusters. Building on previous work we develop a treatment for the mobility of photoexcited electrons and holes based on \textit{ab initio} electronic band structure generated from generalized gradient functionals (PBE and PW91) in a plane wave basis involving large atomic supercells. Populations of photoexcited states are found using steady state solutions to the reduced density matrix in a rotating wave frame approximation. Our previous work found that the addition of Ag nanocluster creates long lived localized electronic excitations that increase the overall absorbance of the system by preventing charge carrier recombination. We explore the effects of the adsorption of the Ag cluster on the photomobility of the system due to increasing hole mobility. [Preview Abstract] |
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JP.00035: Fluorescence spectroscopy and structure of erbium doped tin fluorophosphate glass Jeremy Trimble, Roman Holovchak, Justin Oelgoetz, Carrie Brennan, Andriy Kovalskiy Fluorescence, Raman and EXAFS spectroscopy were used to study glasses of Sn-F-P-O composition doped with different amounts of erbium. Increasing intensity of fluorescence with Er concentration in the range 390-600 nm is observed for 340 nm excitation. Raman spectroscopy measurements show that Er$_{2}$O$_{3}$ modifies the glass spectrum with P-F bonds being replaced by Er principally bonding with F. ErF$_{3}$ and SnF$_{2}$ bands are also identified in the Raman spectra of the doped glasses. EXAFS data give a coordination of Sn to O of 1.5 in an undoped sample, while Er coordination is determined to be 9, indicating that ErF3 is the most likely environment for the rare-earth atoms. Glass transition temperature T$_{\mathrm{g}}$ of 80$^{\circ}$C is determined for undoped glass increasing to 87$^{\circ}$C for the samples doped with 0.25 mol. {\%} of Er. [Preview Abstract] |
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JP.00036: Photostructural Response of Spin Coated and Thermally Evaporated Chalcogenide Thin Films Justin Cook, Stanislav Slang, Miroslav Vlcek, Himanshu Jain, Andriy Kovalskiy The structures of spin coated thin films are investigated and compared to thermally evaporated samples using Raman microscopy and high resolution X-ray Photoelectron Spectroscopy (XPS) methods. It is found that spin coated films are far less photosensitive under illumination of UV and visible light than thermally deposited layers. This combination of IR transparency and low photosensitivity to visible light is especially useful for nonlinear IR optical applications. To quantify this photosensitivity, thin films were exposed to various bandgap and super-bandgap wavelengths of light and the structures of as deposited and exposed thin films are investigated. We have found that arsenic-amine complexes form in solution and some organics remain in the glass even after annealing. Results also show saturation of solvent evaporation during annealing after only a short annealing period. [Preview Abstract] |
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JP.00037: Bioactive Sol-Gel glasses composed of nanometer sized particles Christian Nguyen The glasses of SiO$_{2}$-CaO-P$_{2}$O$_{5}$ family are known by their high bioactivity, which makes them a strong candidates for the application in bone tissue engineering. It was shown recently, that bioactivity of these materials can be further enhanced through the nanoscale design of the scaffolds. The focus of this work was to obtain nanometer sized particles of SiO$_{2}$-CaO-P$_{2}$O$_{5}$ bioglasses by sol-gel method. The sol-gel glass corresponded to 60:36:4 molar ratio of SiO$_{2}$:CaO:P$_{2}$O$_{5}$ was prepared by the mixing acidic and basic solutions, followed by appropriate drying and sintering procedures. Size of the nanoparticles was estimated using XRD patterns. The analysis confirmed the presence of 53-59 nm size particles in our sol-gel derived glass, which then was used to fabricate scaffolds and bioactivity tests. [Preview Abstract] |
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JP.00038: Optimization of a Neutron Detector to Measure (a,n) Reaction Cross-Section Jesus Perello, Fernando Montes, Tony Ahn, Zachary Meisel Nucleosynthesis, the origin of elements, is one of the greatest mysteries in physics. A recent particular nucleosynthesis process of interest is the charge-particle process (cpp). In the cpp, elements form by nuclear fusion reactions during supernovae. At the moment, this fusion process is not well understood and has been proposed to be studied. This process of nuclear fusion, (a,n), will be studied by colliding beam elements produced and accelerated at the National Superconducting Cyclotron Laboratory (NSCL) to a helium-filled cell target. The elements will fuse with a (helium nuclei) and emit a neutron during the reaction. The neutrons will be detected for a count of fused-elements, thus providing us the probability of such reactions. By knowing the probability, we can then calculate how much of a certain element will be created in the cpp, which tells us its abundance. The neutrons will be detected using the Neutron Emission Ratio Observer (NERO). Currently, NERO's efficiency varies for neutrons at the expected energy range (0-12MeV). To study (a,n), NERO's efficiency must be near-constant at these energies. Monte-Carlo N-Particle Transport Code (MCNP6), a software package that simulates nuclear processes, was used to optimize NERO configuration for the experiment. [Preview Abstract] |
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JP.00039: New Levels of \textsuperscript{157}Pm J. Ranger, E.H. Wang, J.H. Hamilton, A.V. Ramayya, J.K. Hwang, A. Navin, M. Rejmund, A. Lemasson, S. Bhattacharyya, Y.X. Luo, J.O. Rasmussen, S.J. Zhu, G.M. Ter-Akopian, Yu. Oganessian Gamma rays in coincidence with isotopically-identified fission fragments using VAMOS++ and EXOGAM, produced using \textsuperscript{238}U on a \textsuperscript{9}Be target, at an energy near the Coulomb barrier have been observed [1,2]. In the present work, we have combined data from the in-beam mass- and Z-gated spectra with the $\gamma$-$\gamma$-$\gamma$-$\gamma$ data from \textsuperscript{252}Cf (SF) to assign transitions and levels in \textsuperscript{157}Pm. In contrast to [3], the transitions previously assigned to \textsuperscript{156}Pm are all seen in the M-Z gated spectra of \textsuperscript{157}Pm and are not seen in the M-Z gated spectra of \textsuperscript{156}Pm. The new expanded levels of \textsuperscript{157}Pm are remarkably similar to those of the levels in \textsuperscript{155}Pm, which have been assigned as a well-deformed rotational band built on $\pi$ 5/2 [532], as in \textsuperscript{155}Pm. [Preview Abstract] |
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JP.00040: Design of a Beam-Monitor Detector for the MUSE Experiment at PSI Mary Mulholland, Steffen Strauch This project focuses on the model of the detector placed downstream of the beam in the Muon Scattering Experiment (MUSE). The beam-monitor is a collection of scintillator bars connected to photomultiplier tubes. Its primary function is to monitor the RF timing of the beam particles, which include electrons, m{\o}ller electrons, muons, and pions of three momenta. Geant4 software is used to run simulations to test a rectangular and a circular design of the monitor. The task is to determine the most efficient design of the scintillator while meeting the requirements of the photomultiplier tubes. The simulations will reveal which design should be manufactured for conducting the physical experiment. [Preview Abstract] |
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JP.00041: Polarization observables in the double pion photo-production with circularly polarized photons off transversely polarized protons Lelia Net The double pion photo-production represents one of the strongest contribution to the total cross-section at high energies and thus it plays an important role in probing the nucleon resonance spectrum. The polarization observables provide additional sensitivity in unraveling the reaction dynamics. The goal of this analysis is to extract the specific polarization observables $ I^{\bigodot}, P^{\bigodot}_{x}, P^{\bigodot}_{y}, P_{x}, P_{y}$ for the $ \gamma p \rightarrow p \pi^{+} \pi^{-} $ reaction. The data were taken as a part of the CLAS g9b ( FROST ) experiment at Jefferson Laboratory, which used a transversely polarized target and a circularly polarized photon beam with energies up to 3 GeV. This work presents an overview of the experiment, the analysis methods and the raw yield asymmetries. [Preview Abstract] |
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JP.00042: Determination of Polarization Transfer Coefficients for Quasi-Free Hyperon Photoproduction off the Bound Neutron Colin Gleason Measurement of the spectrum of the excited nucleon (N*) states provides key information on the relevant degrees of freedom within the nucleon. The determination of the N* spectrum requires an extensive set of high-quality experimental observables, cross sections and polarizations, for a large number of nuclear reactions and over a broad kinematic range. In particular, measurements of polarization observables of strangeness photoproduction are of high importance as many of the resonances that are predicted by quark models, but not observed in pion-nucleon channels, are expected to couple strongly to kaon-hyperon (KY) channels. While in the last decade a large body of polarization and cross section data has been published for strangeness photoproduction off the proton, data off the neutron are very scarce. Our goal is to determine the polarization observables C$_{\mathrm{x}}$ and C$_{\mathrm{z}}$ in the reaction $\gamma $d-\textgreater K$^{\mathrm{0}}\Lambda $p, where the deuteron is used as a neutron target. The data was collected in experiment E06-103 with the CLAS detector at Thomas Jefferson National Accelerator Facility (Jlab) using a circularly polarized photon beam and an unpolarized LD$_{\mathrm{2}}$ target. In this presentation we will discuss our analysis technique and show preliminary results of C$_{\mathrm{x}}$ and C$_{\mathrm{z}}$ for the quasi-free photoproduction of K$^{\mathrm{0}}\Lambda $ off the bound neutron. Our study is part of a larger program carried out at JLab to provide a complete set of observables for strangeness photoproduction off the nucleon. [Preview Abstract] |
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JP.00043: Methods for Scattering and Reactions in Ab Initio Calculations Justin Yang, Dean Lee We develop a method for calculating scattering parameters and phase shifts from the energy spectra of inelastic scattering problems. Scattering in multi-particle systems can be reduced to effective two-cluster scattering using the adiabatic projection method. Our method for phase shift analysis then extracts quantities of interest such as cross sections and amplitudes from the adiabatic Hamiltonian. As a detailed example we apply this method to an exactly solvable coupled-channel test model. Our results show that this method is particularly suited for lattice calculations, and that it holds promise for direct application in lattice effective field theory simulations. [Preview Abstract] |
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JP.00044: Family Structure of Nucleons Rasulkhozha S. Sharafiddinov Any of currents responsible for interactions of leptons and hadrons with virtual gauge bosons can symbolically be expressed in the form of a sum of vector and axial-vector parts of the same charge or dipole moment. This does not imply of course that the same neutron or proton must be simultaneously both a C-even and a C-odd nucleon. We have, thus, a full analogy to the fact that a classification of elementary particles with respect to C-operation admits the existence of the two types of Dirac fermions of the vector and axial-vector nature. If such objects are the neutrons and protons, they will constitute the nucleonic families of a different C-invariance. One group consists of C-even nucleons of vector currents. The second class includes the truly neutral C-odd nucleons of axial-vector currents. The family structure of both types of nucleons and leptons testifies that vector neutron and neutrino possess the same CP-odd electric charge. In contrast to this, truly neutral neutron and neutrino do not distinguish from one another by the availability in them of an equal CP-even electric charge. [Preview Abstract] |
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JP.00045: From the Flavour Symmetry to the Leptonic String Rasulkhozha S. Sharafiddinov In any process of $\beta$-decay originates the birth of a dilepton by the same reason. Such a reason can, for example, be existence in all leptonic families of a unified flavour symmetrical force between the two left (right)-handed fermions of each type. It establishes those connections, at which there exist the left (right)-handed leptons in difermions comparatively for a long time without converting into the right (left)-handed ones, although this is not forbidden. In other words, a flavour symmetrical force relates the two left (right)-handed leptons in flavourless dileptons. They are conserved in the form of leptonic strings until an external action is able to separate their by parts in the particle type dependence. Therefore, a single or a double $\beta$-decay is carried out in nuclei without neutrinos as well as without electrons. In direct experiments, left (right)-handed dileptons are observed instead of electrons. Thus, all properties of electrons fixed in single or double $\beta$-decay one must consider as the characteristic features which refer doubtless only to a leptonic string uniting the electron and its antineutrino. [Preview Abstract] |
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JP.00046: C-invariance Criterion for the Gauge Field Rasulkhozha S. Sharafiddinov To each type of gauge boson corresponds a kind of current. Therefore, the photon and other boson leptonic currents include both vector C-even and axial-vector C-odd components. In these circumstances, it seems possible to separate all gauge bosons into the two classes. The first of them consists of C-invariant vector bosons. They are of course the mediate bosons of vector $(V)$ types of interactions. We include in this class the vector photons $\gamma^{V}$ and weak $W^{\pm}$-bosons. A new example of the first group may be weak vector $Z^{\pm}$-bosons. To the second class apply the axial-vector C-noninvariant bosons. They come forward as the mediate bosons of axial-vector $(A)$ types of interactions. A beautiful example is weak $Z^{0}(W^{0})$-bosons and new axial-vector photons $(\gamma^{A})$ having the Coulomb nature. Recognizing this behavior of the mediate bosons and accepting its ideas about that a classification of elementary particles and currents with respect to C-operation [1] is compatible with gauge invariance, we would change our presentations about matter fields. Without such a changing, the unified field theory construction of elementary particles still remains not quite in line with nature.\\[4pt] [1] R.S. Sharafiddinov, Bull. Am. Phys. Soc. 57, KA.00069 (2012). [Preview Abstract] |
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JP.00047: The One-loop Two Photon Stau -- Neutralino Feynman Diagram Contribution to Co-annihilation Keith Andrew, Eric Steinfelds, Armin Smailhodzic The neutralino is a dark matter candidate arising in the super symmetric extension of the standard model. For the Minimal Super Symmetric Standard Model, MSSM, extension the lightest non-decaying neutral particle can be the neutalino. As a relic particle from cosmic production in the early big bang it should be abundant in galactic halos contributing to anomalous rotation curves. A fraction of the interactions of the neutralinos should annihilate or co-annihilate producing gamma rays that are observable on Earth. The calculation of the branching fraction produces a series of Feynman diagrams that give the cross section and probability for the event to occur. Here we look at the diagram given by the Stau lepton interacting with a neutralino in terms of the Feynman integral at one loop producing a pair of gamma rays. This term should contribute to the galactic dark matter gamma ray flux from the halo. Here we find an analytic expression for one of the co-annihilation cross section terms. [Preview Abstract] |
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JP.00048: The Spin(p, q) Invariant Dirac Equation in n$+$1 dimensional Curved Spacetime Keith Andrew, Eric Steinfelds, Armin Smailhodzic The curved spacetime Dirac equation has a spin connection that in general requires an extra constraint to obey the strong equivalence principle. When the spacetime manifold (M,g) is the base space for a spin bundle and the spinors are representations of a Clifford algebra contained in Spin(p,q) the covariant derivative of the Dirac equation has a spin connection added to the partial derivative. In the vielbein formalism local tetrads are explicitly added to the covariant derivative to give the Dirac-Fock-Weyl spin 1/2 equation in curved spacetime. Alternatively by coupling to the gravitational field with scalar curvature R a variation to the Dirac equation with spin connection can be derived that obeys the strong equivalence principle with spacetime dependent Dirac matrices that fix the form of the spin connection. In both cases the product of the Dirac equation yields a curved spacetime version of the Klein-Gordon equation. Here we develop a procedure to identify the spin connection and examine separable solution constructions for spin 1/2 particles in a general curved spacetime for both types of spin connection in the Dirac equation. [Preview Abstract] |
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JP.00049: Estakhr variables and Flow- like Observables in Heavy Ion Collision Ahmad Reza Estakhr The Estakhr variables are numerical quantities that encode the density, Current density, and angles of Heavy ion in a scattering process in a Lorentz-invariant fashion. If the Minkowski Metric is chosen to be (+,-,-,-) , the Estakhr variables $c_1, c_2,c_3$ are then defined by: $c_1=(J_1+J_2)^2=(J_3+J_4)^2$, $c_2=(J_1-J_3)^2=(J_2-J_4)^2$, $c_3=(J_1-J_4)^2=(J_2-J_3)^2$, Where J$_1$ and J$_2$ are the four-Current density of the incoming heavy Ions and J$_3$ and J$_4$ are the four-Current density of the outgoing heavy Ions, and we are using Planck units (c=1). and then $\sum_{i=1}^{3}c_i=\sum_ {i=1}^{4}\rho_i^2$ [Preview Abstract] |
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JP.00050: Development of Techniques for a Dark Matter Search at the NOvA Far Detector Robert Mina A summary of efforts related to a Dark Matter search using upward going muons at the NOvA Far Detector in Ash River, MN is presented. WIMP annihilations conjectured to occur within the Sun are assumed and corresponding signal MC generation techniques developed for use within the NOvA framework. The properties of the annihilation-produced neutrino signal were studied for simulated WIMPs of various masses and with different annihilation channels. An improved algorithm for extracting timing information from the data was integrated within the Data Driven Trigger, and its performance studied. Special concern was given to trigger on low-energy (less than 20 GeV) muons so as to compete within this regime with similar searches at other neutrino detectors. This study aims to use the neutrino detector as a neutrino telescope by isolating muon events that likely correspond to ``interesting'' astrophysical events and/or physics beyond the standard model. [Preview Abstract] |
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JP.00051: Numerical Methods used in a Dark Matter search at the NOvA Far Detector Eric Fries The NuMI Off-Axis Neutrino Appearance (NOvA) far detector will be used in a search for decay products of weakly interacting massive particles (WIMPs) as indirect evidence for the existence of dark matter. Muons passing through the detector are identified, and each muon has a set of hits associated with its track. The muon is assumed to be travelling at the speed of light from within the Earth out into space (an upward-going muon), and based off of this assumption each hit is assigned an expected time (eT). Each hit also has a measured time (mT). To identify if the track is upward-going or downward-going, mT is plotted against eT, and a likelihood ratio is calculated by comparing a linear fit with slope +1 (upward-going) versus a linear fit with slope -1 (downward-going). To keep trigger rates at a reasonable level of 10 Hz, roughly 99.99 percent of all cosmic muons must be rejected. [Preview Abstract] |
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JP.00052: Development of Novel Methods for Monitoring Aging of the ATLAS TRT Straws Rohit Das, Miaoyuan Liu Straw wire aging damages long-term performance of the Transition Radiation Tracker (TRT), a gaseous straw detector in CERN's Large Hadron Collider (LHC). Formation of silicon-hydrocarbon deposits on the wires causes an aging effect that results in a drop in gas gain. Such polymerizing impurities can permanently alter the detector's geometry and electric field conditions, limiting both its accuracy and lifespan. Before LHC Run II in 2015, during which the LHC will ramp-up to 13 TeV, we seek to create and implement a tool that we can use to better understand the aging effect's consequences for detector performance. By measuring the reduction in gain of the TRT barrel and end-caps during Run I (2010-2012 at 7 TeV), we observe a clear and rising degradation effect present in all sectors of the TRT that may be a result of LHC run conditions. However, no obvious aging was observed in data with stable run conditions. Further studies are needed to isolate the effects caused solely by aging from observed degradation caused by these additional factors. Isolation and monitoring of aging will assist in more effectively understanding its effects on all gaseous straw detectors, commonly used for particle detection in several high energy physics experiments. [Preview Abstract] |
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JP.00053: The Study on Test Beam Data of Mu2e Cosmic-Ray-Veto Scintillation Counter Prototype Yongyi Wu Mu2e is an experiment studying flavor violation in charged lepton interactions through searching for neutrino-less muon to electron decay. In the experiment, cosmic ray muons are anticipated to be a major source of background. They can produce signals indistinguishable to the desired signals in the detector. To cut this background, a cosmic-ray-veto (CRV) system with a high vetoing effeciency has been designed. The veto consists of plastic scintillation counters, and a prototype counter was tested at Fermilab in 2013 using a pulsed beam of $120~\mathrm{GeV}$ protons. The data were analyzed to study the features of the counter including single-channel time resolution, transversal light attenuation, photoelectron yields and the saturation effect of the SiPMs. The better understandings of the prototype's performance will contribute to design improvements enabling the experiment to reach the desired detecting efficiency in a cost-effective manner. [Preview Abstract] |
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JP.00054: Using an Atomic Molecular Optics Laboratory for Undergraduate Research and Mentoring of Physics Students in Georgia Hauke Busch, Michelle Alber, Cristalei Polk, Dimitrius Denize An Atomic and Molecular Optical (AMO) Physics research lab is an excellent tool to train and mentor undergraduate students in advanced laboratory techniques. Students gain valuable basic experience in experimental designs, data acquisition techniques, working with high precision optical equipment, building electronics, and working in the machine shop. Current projects include machining a laser mount and constructing a current supply circuit and temperature controller for a slave laser. Completed projects involved milling the vacuum chamber mounts to support the chamber, and machining Helmholtz coils for the chamber, which is being used to trap the atoms in a Magneto Optical Trap (MOT). This included designing, building and baking out the vacuum chamber, constructing a Rb getter for the chamber, and building the lasers for a saturation-absorption system that is used to probe the 5$^{2}$S$_{1/2}\to $ 5$^{2}$P$_{3/2}$ hyperfine energy transitions of the Rb-85 atom. These energy transitions will be used to frequency-lock a diode laser to trap Rb-85 atoms and then cool them to ultra-low temperatures. The atom cooling will permit observation and measurement of the fundamental properties of atoms. This lab has mentored and supported over ten undergraduate students in the last four years, of which one became a High School Teacher, three joined Ph.D. programs, and one went to optometry school. [Preview Abstract] |
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JP.00055: An undergraduate view of a second year course in physics Farid Salazar, Josuan Calderon, Pedro Soto, Sruthi Narayanan The three authors of this poster who are undergraduate students at FIU worked on the contents of a book as part of an independent study. The fourth author, an undergraduate student at MIT, worked on it remotely. The book was written solely by undergraduate students in physics for undergraduates in physics. It assumes a good knowledge of basics calculus and physics. It covers special relativity starting from Maxwell's equations, black body radiation and the need for quantum mechanics, bound states in quantum mechanics including a model for conductors, insulators and semi-conductors. The book proceeds to discuss basics ideas in statistical mechanics. The problem of free fermi gas and free bose gas is completely worked out. The book ends with a discussion of quantum mechanics in higher dimensions and the need for symmetry operators. The poster shows a flow chart of the topics. [Preview Abstract] |
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JP.00056: ABSTRACT WITHDRAWN |
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JP.00057: Properties of Silicon Photomultipliers Jesse Finley, Richard Riedel Silicon Photomultipliers (SiPM) are an emerging type of photon detector that could potentially replace photomultiplier tubes (PMT). SiPMs are arrays of Avalanche Photodiodes (APD) that operate in Geiger Mode, meaning that the impact ionization from a photon can trigger an avalanche current on a silicon substrate. The advantages of SiPMs over PMTs are their ability to detect single photons, high durability, low operating voltages, low cost, and ability to function in strong magnetic fields. However, SiPMs have a characteristic noise generated from quantum effects which can affect performance when used in applications where a small number of photons are expected. In this study the market and properties of SiPMs (dark noise, afterpulsing, cross-talk) are analyzed in order to evaluate possible applications and feasibility of their use in various fields of research. Testing is done on a Hamamatsu SiPM array to measure the noise of the device and measure the variation of the noise level with temperature and operating voltage. In conclusion, SiPMs have demonstrated to be a low cost alternative to PMTs when the application is such that noise levels are acceptable. [Preview Abstract] |
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JP.00058: Specular Reflection as the Universal Formulation for N-dimensional Diffraction Gratings, N$=$1- 3 Ming Yin, Lei Wang, Michael Wescott, Timir Datta Textbooks in Optics introduce the subject by the familiar 1-d grating formula, a[$\alpha $ -- $\alpha_{\mathrm{i}}$\textbraceright $=$ n$_{\mathrm{x}}\lambda $ , here `a' is the grating constant and $\lambda $ is wavelength. Ever since the development of precession ruling engines by Rowland, 1- dimensional optical diffraction gratings have become ubiquitous, and workhorse in optical devices. Optical cross gratings (2-d) with lines ruled in both x {\&} y directions are treated \textit{mutatis mutandis} by a pair of 1-d grating formula. In 1912, Max von Laue, Nobel Physics for 1914, proposed his three fundamental equations for 3-d, x-ray grating as: a[$\alpha $ -- $\alpha _{\mathrm{i}}$\textbraceright $=$ n$_{\mathrm{x}}\lambda $; b[$\beta $ -- $\beta_{\mathrm{i}}$\textbraceright $=$ n$_{\mathrm{y}}\lambda $ and c[$\gamma $ -- $\gamma_{\mathrm{i}}$\textbraceright $=$ n$_{\mathrm{z}}\lambda$, here $\alpha $, $\beta $ {\&} $\gamma $ ($\alpha_{\mathrm{i}}$, $\beta_{\mathrm{i}}$ {\&} $\gamma _{\mathrm{i}}$ ) are the direction cosines of the outgoing (incoming) x-ray beam. Furthermore for simplicity an orthorhombic crystal structure with lattice constants a, b {\&} c, oriented along each Cartesian axis respectively, were assumed. However, Laue's grating theory was soon superseded by Lawrence Bragg's namesake formula 2dSin($\theta )=$ n$\lambda $. Peter Ewald's reciprocal lattice construction demonstrated that when certain conditions, 3-d diffraction process reduces to Bragg's reflection law. We show that reflection is a generic or universal treatment for one, two or three-dimensional gratings. [Preview Abstract] |
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JP.00059: ``Bullet Time'' Made Possible with Raspberry Pis Austin Freeman, Jonathan Heath, Talon Brown, Annie Dickson-Vandervelde Our SPS group at Francis Marion University has built a bullet-time camera apparatus using Raspberry Pi computer boards. After completion, we plan to use the apparatus for high school outreach. Bullet-time, made famous by ``The Matrix,'' seemingly freezes time and pans around a subject. In order to create this effect, Raspberry Pis are accessed remotely and sent commands to tell them when to begin taking images. The images are then sent back to one Raspberry Pi, where they are placed in a certain sequence to create a video. This process is described in more detail on PiFace Digital's website.\footnote{http://pifacedigital.wordpress.com/2013/12/06/bullet-time-effect-frozen-pi/} [Preview Abstract] |
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JP.00060: Single Photon diffraction and interference John Hodge A previous paper studied photon diffraction and interference required several photons in the experiment at the same time. Interference experiments with intensity of light low enough that only one photon was in the experiment at a time have also showed interference patterns. The previous paper that used the Bohm Interpretation, models of the screen and mask, and the Transaction Interpretation of Quantum Mechanics are combined. The Transaction Interpretation provides a reflected plenum wave that is much faster than the speed of light rather than a reverse time wave. The current investigation is testing the resulting model with toy computer experiments. The simulations include photons from a distance, in Young's experiment, and from a laser. ( http://myplace.frontier.com/$\sim$jchodge/ ) [Preview Abstract] |
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JP.00061: The Ancient Brachistochrone in Today's ``Star-Trek'' World Terry Palmer More than 300 years ago, Johann Bernoulli published one of the great puzzles in mathematics. In ``Acta Eruditorium'' he issued the challenge, ``Given two points A and B in a vertical plane, what is the curve traced out by a point acted on only by gravity which starts at A and reaches B in the shortest time?'' He called this curve, the ``Brachistochrone,'' and his solution was founded on ``Fermat's Principle'' and a uniform gravitational force. Bernoulli's puzzle, now known as the Brachistochrone Problem, stimulated a new field of mathematics called, ``The Calculus of Variations.'' Mathematicians and physicists still solve generalizations of the Brachistochrone Problem using the Calculus of Variations. This paper applies the disciplines of Classical Mechanics and the Calculus of Variations to find Brachistochrones for particles traveling in four speed regimes: Ordinary speeds, Relativistic speeds, Super-Luminal speeds (like a Tachyon traveling faster than light speed) and Ultra-Luminal speeds (Tachyons traveling at nearly infinite speeds). The author finds the Brachistochrones in these speed regimes for two separate forces: the uniform gravitational force (the same force assumed by Bernoulli) and the inverse-square force. [Preview Abstract] |
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JP.00062: Proposal for a More Efficient Acoustic Array Design to Calculate Flow Rate Through a Cylindrical Conduit Kathryn Ham, Quintorious Bivins, Arthur Shue A new design is proposed for the existing acoustic array, a device used to measure the flow rate through a cylindrical conduit via a series of transducers. The original acoustic array consists of a 2.000 inch diameter steel pipe with 128 transducers located along the top, spaced 2.000 inches apart along the length of the pipe. The total length of the original acoustic array in this configuration is over 21 feet long (254 inches). The analog acoustic information obtained from the array is sent through an amplifier, an analog digital converter, and then to a computer to be analyzed in order to determine rate of flow. The new design proposes a 3.000 inch diameter steel pipe with 128 transducers located along the equatorial axis of the pipe, spaced 0.287 inches apart. This new design leads to a more manageable apparatus, as the pipe length needed will be decreased from over 21 feet to less than 3.5 feet in length. [Preview Abstract] |
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JP.00063: Characterization of Multi-Component Bi-containing Chalcogenide Glasses with Raman and Fluorescence Spectroscopy Anthony Thai Bismuth is shown to be a unique dopant in chalcogenide glasses (ChG), leading to a number of interesting phenomena: conduction type reversal from p- to n-type, strong thermo-electric effect, topological insulating behaviour and more. In addition, strong the crystallization ability of Bi can be used to form quantum dots in the structure of amorphous ChG. In this work, we have investigated ChG of the Bi$_{x}$Ga$_{y}$(GeSe$_{4}$)$_{50 - \frac{x+y}{2}}$(GeTe$_{4}$)$_{50 - \frac{x+y}{2}}$ family by Raman and Fluorescence spectroscopy as potential host matrices for Bi-based quantum dots. No fluorescence signal was observed for any of the studied compositions in the 450-1800 nm spectral range under the 300-750 nm excitation. It was found, however, that Bi-based crystallites are formed even under the influence of the probe laser used in Raman spectroscopy. So, quantum dots can be induced in the studied materials by laser pulses, opening a broad range of possible applications. [Preview Abstract] |
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