Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session D1: Welcome Reception and Poster Session I (5:30pm - 7:00pm)Poster Undergraduate
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Room: South Foyer |
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D1.00001: UNDERGRADUATE EDUCATION |
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D1.00002: Social network analysis of a project-based introductory physics course Christopher Oakley Research suggests that students benefit from peer interaction and active engagement in the classroom. The quality, nature, effect of these interactions is currently being explored by Physics Education Researchers. Spelman College offers an introductory physics sequence that addresses content and research skills by engaging students in open-ended research projects, a form of Project-Based Learning. Students have been surveyed at regular intervals during the second semester of trigonometry-based course to determine the frequency of interactions in and out of class. These interactions can be with current or past students, tutors, and instructors. This line of inquiry focuses on metrics of Social Network analysis, such as centrality of participants as well as segmentation of groups. Further research will refine and highlight deeper questions regarding student performance in this pedagogy and course sequence. [Preview Abstract] |
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D1.00003: UNDERGRADUATE RESEARCH (INCLUDING SPS) |
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D1.00004: Measuring the angular and seasonal dependence of the cosmic ray flux at the Earth's surface Amanda Depoian, Matthew Bellis The angular dependence of cosmic rays hitting the Earth's surface is affected by solar winds, the Earth's magnetic field, attenuation factors, and other effects. The overall flux can be affected by the height and density of the atmosphere, which can vary seasonally. This seasonal modulation can affect the analyses of dark matter direct detection experiments, which also look for a modulation in dark matter recoils. We have constructed a standard cosmic ray telescope, consisting of two scintillating paddles, the associate photomultiplier tubes, and some older electronics. We will be pushing the sensitivity and stability of this detector to measure angular and temporal rates over the winter and spring and look for any seasonal variations that can be correlated with environmental conditions. While the location at the Earth's surface in Albany, NY is quite different than the underground laboratories where many dark matter experiments take place, we run this experiment as a proof-of-principle to see what seasonal effects can be measured with the basic equipment available in some undergraduate labs. [Preview Abstract] |
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D1.00005: Thermal Stabilization in a High Vacuum Cryogenic Optical System Rosa Wallace, Jonathan Cripe, Thomas Corbitt The existing technology for gravitational wave detection is limited in part by quantum noise. In our tabletop experiments, we are attempting to lower the noise floor to the quantum limit through the use of a seismically isolated cryogenic high vacuum environment, with the intention of exploring different methods to reduce quantum noise. In the development phase of this environment, we have implemented a customized strategy of ultraviolet irradiation combined with cryogenically cooled radiation shielding to reduce the impact of water vapor and blackbody radiation on the thermal stability of the cryogenic micro-components. [Preview Abstract] |
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D1.00006: Examining Rotational Ground Motion Induced by Tornados Elijah Kessler, Robert Dunn Ring lasers are well known for their ability to detect rotation and to serve as replacements for mechanical gyroscopes. The sensitivity of large ring lasers to various forms of ground motion is less familiar. Since ring lasers preferentially measure rotational ground motion and a standard seismograph is designed to measure translational and vertical ground motion, each device responds to different aspects of ground movement. Therefore, the two instruments will be used to explore responses to microseisms, earthquake generated shear waves, and in particular tornado generated ground movement. On April 27, 2014 an EF4 tornado devastated Vilonia, AR a small town \textasciitilde 21 km from the Hendrix College ring laser. The proximity of the tornado's path to the ring laser interferometer and to a seismograph located in Vilonia provided the opportunity to examine the response of these instruments to tornadic generated ground motion. Our measurements suggest tornadic weather systems can produce both rotational and lateral ground motion. This contention is supported by an after the fact damage survey which found that the tornado flattened a forest in which trees were uprooted and laid down in a pair of converging arcs with the centerline pointed in the direction of the tornado's path. [Preview Abstract] |
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D1.00007: Geophysical Measurements Using a Ring Laser Angela Lamb Low frequency infrasound from weather related events has been studied for a number of years. In this poster, the results from using a large active ring laser as an infrasound detector are presented. A slightly modified cavity design enhances the interferometer’s sensitivity to infrasound. Our results qualitatively agree with several findings from a long term study of weather generated infrasound by NOAA. On April 27, 2014, the 66 km track of an EF-4 tornado passed within 21 km of the ring laser interferometer. An FFT of the ring laser interferometer output revealed a steady tornado generated frequency of 0.94 Hz. The track also passed close to the US Array Transportable Station W41B. This provided the opportunity to examine both the infrasound and ground motion generated by the tornado. Infrasound from three other tornadoes is also included. In all cases the infrasound was detected approximately 30 minutes before the tornado funnel was observed. [Preview Abstract] |
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D1.00008: Dark Energy: Anatomy of a Paradigm Shift in Cosmology Hannah Hocutt Science is defined by its ability to shift its paradigm on the basis of observation and data. Throughout history, the worldviews of the scientific community have been drastically changed to fit that which was scientifically determined to be fact. One of the latest paradigm shifts happened over the shape and fate of the universe. This research details the progression from the early paradigm of a decelerating expanding universe to the discovery of dark energy and the movement to the current paradigm of a universe that is not only expanding but is also accelerating. [Preview Abstract] |
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D1.00009: Low Temperature Deposition of PECVD Polycrystalline Silicon Thin Films using SiF4 / SiH4 mixture Moniruzzaman Syed, Takao Inokuma, Yoshihiro Kurata, Seiichi Hasegawa Polycrystalline silicon films with a strong (110) texture were prepared at 400\textdegree C by a plasma-enhanced chemical vapor deposition using different SiF4 flow rates ([SiF4] $=$ 0--0.5 sccm) under a fixed SiH4 flow rate ( [SiH4] $=$ 1 or 0.15 sccm). The effects of the addition of SiF4 to SiH4 on the structural properties of the films were studied by Raman scattering, X-ray diffraction (XRD), Atomic force microscopy and stress measurements. For [SiH4] $=$ 1 sccm, the crystallinity and the (110) XRD grain size monotonically increased with increasing [SiF4] and their respective maxima reach 90{\%} and 900 {\AA}. However, for [SiH4] $=$ 0.15 sccm, both the crystallinity and the grain size decreased with [SiF4]. Mechanisms causing the change in crystallinity are discussed, and it was suggested that an improvement in the crystallinity, due to the addition of SiF4, is likely to be caused by the effect of a change in the surface morphology of the substrates along with the effect of in situ chemical cleaning. [Preview Abstract] |
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D1.00010: Computational Model for DNA Organization Mediated by Protein Interaction in Prokaryotes Karthik Garimella, Savan Kharel In Escherichia Coli, there are several mechanisms that drive chromosomal organization. We know through experiments that the E. Coli chromosome is condensed into highly structured regions known as macrodomains (MDs). ~One of the regions known as the Terminus undergoes DNA-bridging condensation that form loops between distant DNA sites and it is known to be mediated by a Terminus specific protein, which binds to specific markers within the Terminus region. ~In the absence of Terminus specific protein, however, the Terminus region is known to not condense nearly as much, which will likely impede several biological processes including DNA replication. In order to understand the molecular basis of protein mediation in vivo several models of Terminus specific segregation have been constructed in silico which model DNA as polymer chains. [Preview Abstract] |
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D1.00011: Physical Model of Segregation of E.coli Chromosomes using Molecular Dynamics. Faisal Alnahhas, Savan Kharel Chromosome segregation is one of the most interesting physical processes during a bacterial cell cycle. We will use molecular dynamics simulations which will help us understand how strongly confined polymer segregates. In the presentation, we will discuss how segregation of initially overlapping circular chromosome occurs during a cell cycle. In particular, we will describe the role played by entropic mechanism in the demixing of overlapping circular polymer confined in a cylindrical boundary. We discuss how our polymer chains modeled as an E-coli chromosome experiences an effective repulsion, which ultimately leads to partition driven by the entropic forces. Also, we will also discuss how the segregation of circular chromosome in cylindrical confinement differs from a spherical confinement. Finally, we will discuss the role played by proteins and supercoiling in during the segregation process. [Preview Abstract] |
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D1.00012: Novel Tests of Gravity Below Fifty Microns Gabriela Martinez, Jeremy Johnson, Ian Guerrero, C.D. Hoyle Due to inconsistencies between General Relativity and the Standard Model, tests of gravity remain at the forefront of experimental physics. At Humboldt State University, undergraduates and faculty are designing an experiment sensitive enough to detect gravitational interactions below the 50 micron scale. The experiment measures the twist of a torsion pendulum as an attractor mass is oscillated nearby in a parallel plate configuration, providing time varying gravitational torque on the pendulum. The size and distance dependence of the torque variation will provide a means to determine any deviation from current models of gravity on untested scales. [Preview Abstract] |
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D1.00013: Building the BICEP3 Test Cryostat Samantha Walker, Chao-Lin Kuo, Keith L. Thompson, James Grayson, Ethan Karpel, Val Monticue BICEP3, a ground-based telescope stationed in the South Pole, currently employs a cryostat to observe the polarization of the Cosmic Microwave Background, the earliest light in the Universe, by using devices that take advantage of the superconductivity transition of titanium. The cryostat consists of staggered temperature stages at 300 K, 50 K, 4 K, 2 K, 350 mK, and 250 mK that are maintained by both a pulse tube and three stage helium (He$^{\mathrm{4}}$-He$^{\mathrm{3}}$-He$^{\mathrm{3}})$ sorption refrigerator. However, currently the helium refrigerator is experiencing unanticipated heat loading which is decreasing the fridge cycle hold time and thus the number of hours that BICEP3 can observe for in a given period of time. To address this issue, this past summer I worked at Stanford University to construct a thermally-similar cryostat that will be used to test the thermal conductivities of its various internal components at subKelvin temperatures and determine the source of this heat loading. [Preview Abstract] |
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D1.00014: Computational Techniques in Radio Neutrino Event Reconstruction M. Beydler The Askaryan Radio Array (ARA) is a high-energy cosmic neutrino detector constructed with stations of radio antennas buried in the ice at the South Pole. Event reconstruction relies on the analysis of the arrival times of the transient radio signals generated by neutrinos interacting within a few kilometers of the detector. Because of its depth dependence, the index of refraction in the ice complicates the interferometric directional reconstruction of possible neutrino events. Currently, there is an ongoing endeavor to enhance the programs used for the time-consuming computations of the curved paths of the transient wave signals in the ice as well as the interferometric beamforming. We have implemented a fast, multi-dimensional spline table lookup of the wave arrival times in order to enable raytrace-based directional reconstructions. Additionally, we have applied parallel computing across multiple Graphics Processing Units (GPUs) in order to perform the beamforming calculations quickly. [Preview Abstract] |
(Author Not Attending)
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D1.00015: Classical and Quantum Mechanical Motion in Magnetic Fields K. Cole Newton, Joel Franklin We study the motion of a particle in a particular magnetic field configuration both classically and quantum mechanically. For flux-free radially symmetric magnetic fields defined on circular regions, we establish that particle escape speeds depend, classically, on a gauge-fixed magnetic vector potential, and demonstrate some trajectories associated with this special type of magnetic field. Then we show that some of the geometric features of the classical trajectory (perpendicular exit from the field region, trapped and escape behavior) are reproduced quantum mechanically using a numerical method that extends the norm-preserving Crank-Nicolson method to problems involving magnetic fields. While there are similarities between the classical trajectory and the position expectation value of the quantum mechanical solution, there are also differences, and we demonstrate some of these. [Preview Abstract] |
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D1.00016: Recursive Techniques for Computing Gluon Scattering in Anti-de-Sitter Space Claude Shyaka, Savan Kharel The anti-de Sitter/conformal field theory correspondence is a relationship between two kinds of physical theories. On one side of the duality are special type of quantum (conformal) field theories known as the Yang-Mills theory. These quantum field theories are known to be equivalent to theories of gravity in Anti-de Sitter (AdS) space. The physical observables in the theory are the correlation functions that live in the boundary of AdS space. In general correlation functions are computed using configuration space and the expressions are extremely complicated. Using momentum basis and recursive techniques developed by Raju, we extend tree level correlation functions for four and five-point correlation functions in Yang-Mills theory in Anti-de Sitter space. In addition, we show that for certain external helicity, the correlation functions have simple analytic structure. Finally, we discuss how one can generalize these results to n-point functions. [Preview Abstract] |
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D1.00017: The Scintillator-Layered Imaging Microscope for Environmental Research Emily Buchanan, M. F. Kidd, S. R. Elliott, K. Rielage In microbial ecosystems, a high-throughput analysis can match microorganisms with the compounds they metabolize. This is a vital process, but the current tools are limited in both time and resolution. A new tool, SLIMER (the Scintillator-Layered Imaging Microscope for Environmental Research), will incorporate a thin-film microcolumnar scintillator in a standard fluorescent microscope, to allow measurement of both fluorescence and radioactivity in a single step and to improve by a factor of 10 the resolution of current tools. In order to study the properties of SLIMER, a simulation to illustrate the topology of events was developed from the ground up with the GEANT4 toolkit. The simulation consists of CsI tubes, 1 um in diameter, in a 1 cm by 1 cm array, with a C-14 source. The GEANT4 package for radioactive decay was used to model the decay of C-14, and the package for optical photon processes was used to realistically model the optics of scintillation. The HepRApp Visualization Browser was used to provide a visual model of the scintillator, source, and particle tracks. The developed simulation provides useful information about the capabilities and properties of SLIMER, which in turn will impact the way microbial ecosystems and their impact on the environment are studied. [Preview Abstract] |
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D1.00018: Structural Colors of Birds Cecilia Hall, Natalia Dushkina Structural colors create iridescent colors in bird feathers. ~The goal is to understand why structural colors act the way they do in certain situations. ~The research conducted over the course of the fall semester was to understand the optical phenomenon producing colors in individual barbules. ~Through the use of a polarizing optical microscope, certain hypotheses were built to explain certain phenomenon. ~Using a dark field illumination involving light acting at wide angles in microscopy, the barbules were not affected by polarization. ~So it can be suggested that the barbules have certain characteristics, possibly internal, which prevents wide-angle polarization. More recently, it was found that the barbules, when stacked upon one another, create a discoloration at the cross over point. ~It can be suggested that the barbules act as thin films and create a situation of thin film interference. ~More data will be taken using the Scanning Electron Microscope as well as getting cross sectional data to help understand the internal characteristics of the barbules. ~ [Preview Abstract] |
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D1.00019: Quantitative Determination of the Breakdown Field of Air from Van de Graaff Generator Discharge John Beach, Bridget Chartrand, Hugh Gallagher The Van de Graaff generator (VG) is ubiquitous in electrostatic demonstrations because of the large static charge and dramatic sparks produced. We have developed a novel technique for determining the breakdown field of air using the VG. When a spark occurs, the force of attraction between the VG and a discharge sphere suspended above it is measured by a Pasco force sensor. At this time the charge is not symmetric but pulled towards the near side of the spheres by mutual attraction. In order to interpret the measured force in terms of the breakdown field, an accurate model of the charge distribution is needed. Using the method of images for a spherical conductor in an iterative fashion we can provide this model. The electric field in the vicinity of the spheres is then calculated from the charge distribution and its maximum value is the breakdown field. In preliminary work, we determined the breakdown field to be 3.1x10$^{\mathrm{6}}$ N/C at 24.9 C and 18{\%} relative humidity. We will report our most recent determination of the breakdown field using this method and discuss the validity of the results in terms of accepted values, experimental limitations and sensitivity to the charge distribution model. [Preview Abstract] |
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D1.00020: Sillicon Photomultiplier and Scintillator Bar Systems Mark Shelor, Leonardo Elizondo, Stefan Ritt To analyze extraterrestrial cosmic rays via precise measurements of airshower axes directions of penetrating particles such as muons, we constructed a model detector consisting of two 1-meter long scintillator bars. Each bar is fitted with green wavelength shifting fibers to modulate input for two silicon photomultiplier (SiPM) light detectors to record light produced by cosmic rays via scintillation. The purpose of the experiment is to determine the performance of these devices. Two makes of SiPMs were evaluated -- from AdvanSiD and Hamamatsu. In order to filter out noise, timing measurements of the apparatus were performed under several trigger conditions such as coincidence trigger with 2 photomultiplier detectors, as well as SiPM detector arrays in self-triggered mode. The DRS4 Digitizer 4-channel fast waveform sampler digitized SiPM detector waveforms. Signals were analyzed with the CERN PAW package. The speed of light in the scintillator using the SiPM modules was found to be approximately 66{\%} of the speed of light in a vacuum which is in accordance with the index of refraction for the fibers given by the manufacturer's specifications. The results of our timing measurements would be presented. [Preview Abstract] |
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D1.00021: The Application of Forced Resonance in Conjunction with Standard Cryogenic Treatment of Metals Austin Evans, Kyle Leadlove, James Seyfert, Casey Watson, Peter Paulin We explore modifications to the basic cryogenic procedures utilized by 300 Below Inc. to strengthen metal components.~ We consider the effects of adding forced resonance in our efforts to further optimize the cryogenic treatment -- i.e., to augment the already improved tensile strength, shear strength, thermal and electrical conductivity, etc. resulting from 300 Below Inc.'s traditional cryogenic process.~ We report on the wear-test performance of resonance treated samples relative to standard cryogenically treated samples and control samples. [Preview Abstract] |
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D1.00022: The Effects of DC Electromagnetic Stimuli in Conjunction with Standard Cryogenic Treatment of Metals Kyle Leadlove Leadlove, Austin Evans, James Seyfert, Casey R. Watson, Peter Paulin We explore modifications to the basic cryogenic procedures utilized by 300 Below Inc. to strengthen metal components.~ We consider the effects of adding DC electromagnetic stimuli in our efforts to further optimize the cryogenic treatment -- i.e., to augment the already improved tensile strength, shear strength, thermal and electrical conductivity, etc. resulting from 300 Below Inc.'s traditional cryogenic process.~ We report on the wear-test performance of DC magneto-cryogenic treated samples relative to standard cryogenically treated samples and control samples. [Preview Abstract] |
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D1.00023: The Effects of AC Electromagnetic Stimuli in Conjunction with Standard Cryogenic Treatment of Metals James Seyfert, Austin Evans, Kyle Leadlove, Casey Watson, Peter Paulin We explore modifications to the basic cryogenic procedures utilized by 300 Below Inc. to strengthen metal components. We consider the effects of adding AC electromagnetic stimuli in our efforts to further optimize the cryogenic treatment -- i.e., to augment the already improved tensile strength, shear strength, thermal and electrical conductivity, etc. resulting from 300 Below Inc.'s traditional cryogenic process. We report on the wear-test performance of AC magneto-cryogenic treated samples relative to standard cryogenically treated samples and control samples. Replace this text with your abstract body. [Preview Abstract] |
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D1.00024: Phase Space Density Constraints on the Properties of the Dark Matter Particle Benjamin Woodall, Zech Miller, Hunter Somers, Casey Watson We show that there is a strong correlation between the pseudo-phase space density and half-light radii of Milky Way Dwarf Spheroidal galaxies. We explore the implications of this scaling for the properties of the dark matter particle. [Preview Abstract] |
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D1.00025: One-Dimensional Random Walks with One-Step Memory Kevin Piaskowski, Michael Nolan Formalized studies of random walks have been done dating back to the early 20$^{\mathrm{th}}$ century. Since then, well-defined conclusions have been drawn, specifically in the case of one and two-dimensional random walks. An important theorem was formulated by George Polya in 1912. He stated that for a one or two-dimensional lattice random walk with infinite number of steps, N, the probability that the walker will return to its point of origin is unity. The work done in this particular research explores Polya's theorem for one-dimensional random walks that are non-isotropic and have the property of one-step memory, i.e. the probability of moving in any direction is non-symmetric and dependent on the previous step. The key mathematical construct used in this research is that of a generating function. This helps compute the return probability for an infinite N. An explicit form of the generating function was devised and used to calculate return probabilities for finite N. Return probabilities for various memory parameters were explored analytically and via simulations. Currently, further analysis is being done to try and find a relationship between memory parameters and number of steps, N. [Preview Abstract] |
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D1.00026: Computational Analysis of Intermolecular Coulombic Decay Effects in~DNA nucleotide Photoionization E. L. Vargas, J. Robertson, V. M. Andrianarijaona Intermolecular Coulombic Decay (ICD) is the process of how electrons return to their original state after excitation and how this affects their immediate environment. In a previous research presentation$^{\, }$we had considered the hypothetical applications of Intermolecular Coulombic Decay on the adhesiveness of coding proteins within DNA molecules. This presentation is a continuation of the previous [1] in that the results of our DFT-based computational calculations of the ionization potentials of nucleotides and their excitation energies will be presented, as well as how they influence their surroundings. [1] E.L. Vargas, et al.: http://meetings.aps.org/Meeting/MAR15/Session/P1.109 [Preview Abstract] |
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D1.00027: Software Development for Ring Imaging Detector Benjamin Torisky Jefferson Lab (Jlab) is performing a large-scale upgrade to their Continuous Electron Beam Accelerator Facility (CEBAF) up to 12GeV beam. The Large Acceptance Spectrometer (CLAS12) in Hall B is being upgraded and a new Ring Imaging Cherenkov (RICH) detector is being developed to provide better kaon -- pion separation throughout the 3 to 12 GeV range. With this addition, when the electron beam hits the target, the resulting pions, kaons, and other particles will pass through a wall of translucent aerogel tiles and create Cherenkov radiation. This light can then be accurately detected by a large array of Multi-Anode PhotoMultiplier Tubes (MA-PMT). I am presenting an update on my work on the implementation of Java based reconstruction programs for the RICH in the CLAS12 main analysis package. [Preview Abstract] |
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D1.00028: A low-latency Glitch Classification Algorithm Based in Waveform Morphology Hunter Gabbard, Soma Mukherjee, Robert Stone We present a novel and efficient algorithm for classification of signals that arise in gravitational wave channels of the Laser Interferometer Gravitational Wave Observatory (LIGO). Using data from LIGO’s sixth science run (S6), we developed a new glitch classification algorithm based mainly on the morphology of the waveform as well as several other parameters (signal-to-noise ratio (SNR), duration, bandwidth, etc.). This is done using two novel methods, Kohonen Self Organizing Feature Maps (SOMs), and discrete wavelet transform coefficients. This study shows the feasibility of utilizing unsupervised machine learning techniques (SOMs) in order to display a multidimensional trigger set in a low-latency two dimensional format. [Preview Abstract] |
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D1.00029: TESTS OF PHYSICS LAWS |
(Author Not Attending)
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D1.00030: On the Formal--Logical Analysis of the Foundations of Mathematics Applied to Problems in Physics Temur Z. Kalanov Analysis of the foundations of mathematics applied to problems in physics was proposed. The unity of formal logic and of rational dialectics is methodological basis of the analysis. It is shown that critical analysis of the concept of mathematical quantity -- central concept of mathematics -- leads to the following conclusion: (1) The concept of ``mathematical quantity'' is the result of the following mental operations: (a) abstraction of the ``quantitative determinacy of physical quantity'' from the ``physical quantity'' at that the ``quantitative determinacy of physical quantity'' is an independent object of thought; (b) abstraction of the ``amount (i.e., abstract number)'' from the ``quantitative determinacy of physical quantity'' at that the ``amount (i.e., abstract number)'' is an independent object of thought. In this case, unnamed, abstract numbers are the only sign of the ``mathematical quantity''. This sign is not an essential sign of the material objects. (2) The concept of mathematical quantity is meaningless, erroneous, and inadmissible concept in science because it represents the following formal-logical and dialectical-materialistic error: negation of the existence of the essential sign of the concept (i.e., negation of the existence of the essence of the concept) and negation of the existence of measure of material object. [Preview Abstract] |
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D1.00031: Measuring thorium, uranium and lead in the ancient r-process star HE1523-0901 Anna Frebel Some old metal-poor Galactic stars formed from material enriched in the hehaviest elements made in the r-process. Their measured neutron-capture abundances near-perfectly match the scaled solar r-process pattern for the elements above Ba. This universality enables age measurements of these rare r-process stars. In the case of star HE 1523-0901, an age of 13.2 Gyr was derived from multipe abundance ratios involving Th, U and other heavy stable elements. We now present new results on a Pb abundance measurement. Our Pb measurement of the total produced lead strongly constraints the various Pb production channels in the r-process that occur in addition to the decay component by the Th and U decay. We find good agreement with current "waiting point" models for the production of elements in the actinide region. This implicitly also improves the r-process model used for obtaining initial production ratios on which the stellar ages deteminations are based. With this good level of agreement, HE 1523-0901 is already a vital probe for observational ``near-field'' cosmology by providing an independent lower limit for the age of the Universe. [Preview Abstract] |
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D1.00032: ABSTRACT WITHDRAWN |
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D1.00033: Development of a Torsion Balance Experiment to Investigate Gravitation at the Sub-Millimeter Range Adam Archibald, Mike Abercrombie, Tsitsi Nousinov, Kasey Wagoner, Ramanath Cowsik This poster covers our efforts to investigate possible violations of the inverse-square law of gravity at ranges below 1 cm. An instrument of novel design, sensitive to such violations, has been constructed and being operated in the basement of Rudolph Hall, Washington University in Saint Louis. We discuss the main design features and calibration of the instrument to assess its sensitivity. We provide the first results from our study of possible violations for a range of several millimeters. We conclude with a discussion of prospects for the future. [Preview Abstract] |
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D1.00034: A search for WIMPs with the CoGeNT public dataset Matthew Bellis, Chris Kelso, Juan Collar Since December 2009, the CoGeNT experiment has recorded interactions in the detector with the goal of either detecting dark matter or setting stringent limits on the mass and cross-section of these particles, assuming that dark matter is a form of WIMP (Weakly Interacting Massive Particle). The collaboration has made public this dataset to the broader community and this analysis is based on that dataset. We perform an unbinned, maximum likelihood fit to the data, accounting for known backgrounds and systematic effects. \textbraceleft articlar care is paid to detector effects which can mimic the energy distribution of WIMP interactions. We model the WIMP signal, parametrized by energy deposition and time of year, mass, cross-section, and choice of local WIMP velocity distribution. Monte Carlo studies are performed to verify the stability and sensitivity of the fits and all code used in the analysis is made publicly available. The current status of this analysis will be presented. [Preview Abstract] |
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D1.00035: HIGH ENERGY PARTICLE ACCELERATORS AND COLLIDERS |
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D1.00036: Sensors for the CMS Forward Pixel Phase 1 Upgrade Kamuran Dilsiz The next incarnation of the CMS forward pixel detector, to be installed during the year end extended technical stop 2016-17, will need to survive an integrated luminosity of 300 $fb^{-1}$ with the inner radius of the active region of the disks decreasing from 6 to 4.5 cm. Based on the Run 1 experience and irradiation studies, the Phase 1 FPIX sensors will again be n-on-n DOFZ silicon, with parameters similar to those in the present run. We will review the design choices including a study during the prototyping phase to explore different p-stop layouts. Results from the quality assurance probing of the full production of sensor wafers will be described. The IV measurements are particularly impressive with current densities in range of 3-4 nA/$cm^{2}$ at the full depletion voltage. [Preview Abstract] |
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D1.00037: Generation and Characterization of Magnetized Bunched Electron Beam from a DC High Voltage Photogun Riad Suleiman, Matthew Poelker, Jay Benesch, Fay Hannon, Carlos Hernandez-Garcia, Yan Wang To maintain ion beam emittance and extend luminosity lifetime, the Jefferson Lab design of the Electron Ion Collider includes a bunched magnetized electron beam cooler as part of the Collider Ring. We are building a prototype magnetized gun using our newly commissioned 325 kV inverted-insulator DC high voltage photogun. This contribution describes planned measurements of beam magnetization as a function of bunch charge and average current, and laser beam size and magnetic field strength at the photocathode. Results will be compared to particle tracking code simulations. Photocathode lifetime at milli-ampere current will be compared to beam lifetime with no magnetization, to explore the impact of the magnetic field on photogun operation. Combined, these measurements and simulations will benchmark our design tools and provide insights on ways to optimize the electron cooler. [Preview Abstract] |
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D1.00038: BEAM PHYSICS |
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D1.00039: Generating a Reduced-energy Antiproton beam using Channeling Electrostatic elements (GRACE) Gerard Lawler, Nicola Pacifico A device was designed for Generating a Reduced-energy Antiproton-beam using Channeling Electrostatic elements (GRACE). A series of einzel lenses and electrodes are used to create a slow beam of antiprotons with tunable mean energy ($0$ to $16$ keV with root mean squared value below $20$\%) using antiprotons (mean energy of $5$ MeV) from the Antiproton Decelerator (AD) at CERN. Degrader foil is in place, so GRACE further deflects the beam bunches away from the annihilation products, focusing them on a $14$ mm x $14$ mm detector. Manufacturing parameters were found using simulations written in C++. The device is currently in use by the Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) collaboration at CERN, which seeks to measure the sign of the gravitational constant for antimatter by performing interferometry studies on an antihydrogen beam. GRACE delivers on the order of 10 events per beam bunch from the AD. Antiprotons will eventually be used together with a pulse of positronium atoms to make antihydrogen atoms with horizontal velocity. GRACE is being used to perform intermediary experiments concerning interferometry of antiprotons, an important stepping stone on the way to measuring the sign of gravity. [Preview Abstract] |
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D1.00040: GENERAL |
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D1.00041: Calibration of the HMS Scintillators in Hall C at Jefferson Lab. Maria Manrique, Simona Malace, Jonathan Castellanos, Mark Jones, Eric Kvenlog, Charles Miller Jefferson Laboratory has undergone a multi-year upgrade in order for the accelerator to provide an electron beam with a maximum energy of 12 GeV. To accommodate the high energy beam, a new experimental hall (Hall D) has been built, and the existing halls (A, B, and C) have been upgraded. In Hall C specifically, the Super High Momentum Spectrometer (SHMS) was added and the High Momentum Spectrometer (HMS) was upgraded to sustain the 12 GeV beam. This poster focuses on the re-calibration of the HMS scintillator detector in order for the HMS to be ready to take scientific data, Spring 2016. The detector is made of BC-404 plastic scintillator bars arranged in four planes, both vertically and horizontally, to maximize particle detection/localization. The light produced by the scintillators is detected by XP2262 Photomultiplier Tubes (PMTs) located at both ends of each bar. The detector re-calibration involved checking for and fixing light leaks and gain matching all of the PMTs using a $^{60}$Co source to ensure 100{\%} detection efficiency for the particles of interest. [Preview Abstract] |
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D1.00042: A New Computational Window into Fractal Morphology Aritra Ghosh, R. Batabyal, G. P. Das, B.N. Dev We have computationally investigated on-lattice diffusion limited aggregation (DLA) involving edge diffusion and compared the results with the standard DLA model. For both cases, we observe the existence of a crossover from the fractal to the compact regime as a function of sticking coefficient. However, our modified DLA model including edge diffusion shows an extended fractal growth regime like an earlier theoretical result using realistic growth models and physical parameters [Zhang et al., Phys. Rev. Lett. 73 (1994) 1829]. While the results of Zhang et al. showed the existence of the extended fractal growth regime only on triangular but not on square lattices, we find its existence on the square lattice. There is experimental evidence of this growth regime on a square lattice. The standard DLA model cannot characterize fractal morphology as the fractal dimension (Hausdorff dimension, DH) is insensitive to morphology. It also predicts DH $=$ DP (the perimeter dimension). For the usual fractal structures, observed in growth experiments on surfaces, the perimeter dimension can differ significantly (DH $\ne $ DP) depending on the morphology. Our modified DLA model shows minor sensitivity to this difference.\newline \\Reference:- Aritra Ghosh, R. Batabyal, G.P.Das and B.N.Dev ``An extended fractal growth regime in the diffusion limited aggregation including edge diffusion'' AIP Advances 6, 015301 (2016). Work done at: Presidency University, Kolkata [Preview Abstract] |
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D1.00043: Purging of hydrogen in spaceplane through liquid helium with analysis on interaction through smooth particle hydrodynamics Arpan Sharma The purging of liquid hydrogen in drain lines of spaceshuttle was carried out using helium but for the analysis through smooth particle hydrodynamics(SPH) liquid helium is used to purge the hydrogen fuel. The kernel function is developed for the particle based interaction. The analysis of interaction at different time t(0), t(1), t(2),.. is performed. The aim of the project is to develop computational environment for the purging by particle based interaction for simulation purpose. The particle based simulation is meshless method and mesh-free methods are more flexible than finite elements, because they do not depend on a fixed topological connectivity. [Preview Abstract] |
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D1.00044: Suppression of Turbulence using Electrified Granular Material Jansen Keith L. Domoguen, Joel Tiu Maquiling This research explores an understanding of the transition mechanism between laminar and turbulent regimes of fluid flow using a novel approach of coupling fluid flow with electric phenomena. This was done by electrifying granular material inside a simple capacitor-like electrification chamber using a DC power source. The granular material used was sawdust. The fluid introduced was plume from from burned mosquito coil and burned incense stick. The suppression of turbulence is quantified through a measurement of the extension of the maximum laminar flow length ($L_{max})$. Videos of the plume behavior were taken using a Sony Cybershot-WGC camera while image analysis of the plume behavior was done using ImageJ image analysis software. Results reveal significant increase in $L_{max}$ for the plumes exposed to electrified sawdust. Plots of $L_{max}$-versus-applied voltage and $L_{max}$-versus-mass-of-sawdust reveal nonlinear increasing trends. Coupling constants \quad $\kappa $ and $\varsigma $ were theoretically derived to explain the coupled states between the fluid flow and the electrified sawdust. [Preview Abstract] |
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