Bulletin of the American Physical Society
82nd Annual Meeting of the APS Southeastern Section
Volume 60, Number 18
Wednesday–Saturday, November 18–21, 2015; Mobile, Alabama
Session J1: SESAPS Poster Session |
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Chair: Mark Spraker, University of North Georgia Room: Riverview Plaza Hotel Preconvene II |
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J1.00001: Filtering out pesky air pollutants with XRF Amanda Kennell, Thomas Norris, Sarah Formica A monochromatic, micro-X-ray Fluorescence Spectroscopy ($\mu$XRF) system is used to analyze spider webs to detect metal particulates that are commonly found in polluted air and automobile exhaust. In order to quantify the amount of Fe particulates in the environment, a calibration curve is being constructed by contaminating the spider webs with a known amount of Fe particulates, which is then varied in each web to compare concentration of Fe to X-ray counts from the detector. This calibration curve will be utilized to determine the Fe concentration in different spider webs from different locations outside which will quantify the amount of Fe in their surrounding environment. Later, calibration curves will be built for other heavy metals that have been found in the environment such as Zn, Co, Mg, Pt, and Pb. The spider webs that are in higher traffic regions show higher amounts of heavy metals in them compared to lower traffic webs. To show that spider webs are an efficient method for determining air pollutants, government standard air filters, used for detecting pollutants, are being compared to a spider web to see which filter is able to collect the most particulates in the environment in a set amount of time. [Preview Abstract] |
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J1.00002: Geant4 Simulations for Radiation-Induced Atmospheric Effects Tyler Reese, Chris Winstead Computational methods are being employed to model the effects of radiation energy deposition in the atmosphere in conjunction with ongoing validation experiments. The computational approach is based on Geant4, an open source C$++$ toolkit that incorporates a large selection of models for simulating particle transport for a variety of particle types, materials, and processes in addition to handling the geometry and visualization of the simulation. One of the first tasks explored with Geant4 was using it to aid in the selection of radiation sources for laboratory experimentation. While simple calculation methods using stopping powers and CSDA ranges can be used to determine expected energy deposition and range for various radiation sources, Geant4 simulations of these values provided confirmation that the simulations were well constructed and yielded a much more comprehensive picture of these effects within the experimental setup. Examples and corresponding results will be presented for an alpha source, two beta sources, and a gamma source. These provide a useful perspective when considering the selection of laboratory radiation sources and also demonstrate why alpha and low energy beta sources are the initial choices for experimentation. Subsequent work will extend the capability of the simulations for low energy interactions (e.g. molecular processes) and include the use of these results in chemical kinetics calculations. [Preview Abstract] |
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J1.00003: CRDS Measurements of Radiation-Induced Atmospheric Products Sidney Gautrau, Tyler Reese, Patrick Ables, Chris Winstead The purpose of this project is to validate computational models under development for radiation-induced atmospheric effects. Cavity Ringdown Spectroscopy (CRDS) is used to measure the concentration of chemical products generated as a result of radiation interactions in a controlled atmosphere. Experiments are conducted in a vacuum chamber interfaced with a gas introduction system used for control of the initial atmospheric composition, which in turn is confirmed using a quadrupole mass spectrometer. A tunable dye laser provides wavelength flexibility for detection of a variety of chemical products generated by radiation sources mounted at the center of the vacuum chamber. CRDS measurements are to be performed under a variety of atmospheric and radiation conditions for validation of modelling results. This poster briefly explains the advantages of using CRDS for these measurements and includes a description of the modifications required to enable the use of an existing vacuum system with the mass spectrometer and the dye laser systems. Experiments conducted for calibration of the CRDS system are outlined and alpha radiation-induced ozone measurements are presented for an N$_{2}$/O$_{2}$ mixture with different initial O$_{2}$ concentrations and radiation source activities. Future work will include measurements of other anticipated species such as NO, NO$_{2}$, and HNO$_{3}$. [Preview Abstract] |
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J1.00004: Developing CubeSats for Remote Earth Sensing Michael Phillips, Michael Fogle, Jean-Marie Wersinger, Luke Marzen, Michael Briggs, Peter Jenke There are two Auburn University Student Space Program (AUSSP) missions in which CubeSats are being used for cutting edge scientific research. The Terrestrial Rays Analysis and Detection (TRYAD) mission will utilize two student built nanosatellites to detect terrestrial gamma ray flashes (TGFs). The satellites will be able to determine TGFs beam profile and tilt characteristics while using differential drag for separation control. TRYAD data will be correlated with TGF data collected by very low frequency (VLF) radio receivers on Earth. The Hyperspectral Instrument for Cubesats (HYSPIC) will cover a spectral range of 350 to 1000 nm with 7 nm resolution along with having a RGB spatial imager. The ground sampling distance (GSD) of HYSPIC will be approximately 30 m in the hyperspectral bands and 3 to 5 m for the RGB imager at a 500 km altitude. The data cubes in which hyperspectral data is traditionally stored can be very large. HYSPIC will be using micro mirror array technology to implement compressive sensing techniques. Data reconstruction will be performed on the ground to minimize satellite data handling. [Preview Abstract] |
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J1.00005: Nonlinear Dynamical Control for Passively Q-switched Lasers Marcos Nve-Nsi, Zechariah Rice, Makhin Thitsa Q switched lasers are high energy laser pulses of short duration which are prevalent in applications ranging from medical field to optical communication. Passively Q switched lasers do not require external switches for Q-switching since the saturable absorbers doped in the laser material function as the internal switches. One of the main challenges in developing laser material for passive Q-switching is customizing the pulse shape and energy since there are few parameters in passively Q switched laser dynamics that can be influenced externally. In this paper theoretical tools from the field of nonlinear dynamical control systems are applied to design a feedback controller circuit, which can produce a Q-switched pulse with customized characteristics by varying the pump rate, which can be influenced by the pump power. Cr:YSO Q-switched Cr:LiSAF laser is used as an example to demonstrate our method. Both theoretical analysis of the method and the numerical simulation results will be presented. [Preview Abstract] |
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J1.00006: Ion-momentum imaging of dissociative electron attachment dynamics in N${_2}$0 and HCCH James Edmond, Dylan Reedy, Ali Moradmand, Daniel Haxton, Ann Orel, Thomas Rescigno, Allen Landers, Michael Fogle We have studied the low-energy dissociative electron attachment (DEA) interactions for nitrous oxide and acetylene at 2.3 eV and 3 eV shape resonances, respectively. We observed dissociation using an ion-momentum imaging apparatus based on the Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS) method in which a molecular beam produced by a gas jet is crossed by a pulsed electron beam. The DEA reaction involving nitrous oxide resulted in oxygen anions whose angular distributions implied the dominant interaction state at its energy was ${^2}\Pi$ and suggested a dissociation via a near linear configuration, contradicting previous work stating that a significant $\Sigma$ contribution resulted in a bending dynamic upon attachment. For acetylene, the DEA reaction produced C${_2}$H anions at a ${^2}\Pi{_g}$ resonance whose measured angular distributions were indicative of a bending dynamic in the dissociation process. While this bending mechanism has been hinted at by previous experimental observations, direct observations never occurred. Changes to our theoretical predictions have led to good agreement with our experimental fragment distribution, and our observed Kinetic Energy Release for the anions showed low energy fragments alongside internal excitation of said fragments. [Preview Abstract] |
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J1.00007: Highlighting Coronary Vasculature of Perfusion-fixed Hearts using Magnetic Resonance Imaging Jason Kelly Magnetic resonance imaging, or MRI, of perfusion-fixed hearts is highly effective at obtaining high quality images of soft tissue and fat. Computed tomography, or CT, scans are preferred for imaging vasculature of the perfusion-fixed hearts. CT scans, however, have a much lower resolution than MRI, which can show details as small as 0.1mm. Gadolinium-based contrast agents can be used in MRI to brighten images at the location of delivery. A method for obtaining a model of both the tissue and vasculature of ex-situ perfusion-fixed human hearts using a single imaging method, MRI, is needed. Balloon catheters were inserted into the coronary sinus and coronary arteries to fill the vasculature with various solutions. The gadolinium-based contrast resulted in an image that fluoresced well, but the contrast leaked from the vasculature into the tissue, thus the delivery method needed to be improved. After the vasculature was properly occluded, solutions including fish oil, graphite microspheres, and mineral oil were explored with varying success. More agents are being explored in an attempt to optimize the imaging of coronary vasculature, myocardium, and adipose tissue using a single imaging modality. [Preview Abstract] |
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J1.00008: Void Detection in Friction Stir Welding Using the Spindle Motor Current Brandon Osborne, Isaac Wilbur, William Longhurst, Bryan Gaither Friction Stir Welding (FSW) is a solid-state process that uses downward forging pressure and frictional heat from a rotating tool to soften and join two metals. FSW`s ability to join metals with low melting points and to reduce the probability of imperfections found historically in traditional fusion welding makes it a preferred method for a variety of materials. Despite its advantages, however, voids can still form under improper welding conditions. Because voids reduce the structural integrity of the weld, the ability to detect them in situ would provide insight into how to minimize their formation. Welding torque has been shown to be a useful parameter for detecting the presence of voids. To indirectly monitor welding torque, a clamp-on current sensor was attached to the mill spindle motor and the current signal was recorded. The signal was then Fourier transformed to determine its constituent frequencies. During normal welding conditions the frequency content showed a component around 14 Hz; however, when the tool encountered a void in the workpiece the 14 Hz component disappeared and the component in the 1-4 Hz range increased. [Preview Abstract] |
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J1.00009: Nucleosynthesis in Type II Supernova Carrie Elliott, William R Hix, Amos Manneschmidt, Austin Harris Type II Supernovae are the most common class of the ``core collapse'' supernovae. These dramatic events involve the violent destruction of a high mass star (greater than approximately 8 solar masses). Their death is a result of an immense self-gravitational force becoming unbalanced as nuclear fusion ceases in the stellar core, leading to the collapse of the core to form a neutron star. The development of the explosion launches a shockwave that causes fusion into heavier elements as it progress through the star. This results in the production of most of the heavy elements in the universe. The complex nature of the explosion (its hydrodynamics, transport of energy, and the created isotopes) have recently been studied with increasing physical fidelity and spatial dimensionality. Detailed nucleosynthesis from models of these supernovae is calculated in a post-processing step, using the thermodynamic trajectories of tracer particles evolved within the models. My work on the project has been to develop the tools to visualize the results of post-processing calculations on the multi-dimensional grid of the original model. I have improved upon a simple nearest-neighbor method of interpolation of density in-between elements to account for the issues with initial particle alignment and boundaries, to develop a smooth interpolation free of gaps or bands. This smooth interpolation can also be applied the re-mapping of isotope abundance to provide a visual presentation of the distribution of isotopes in the exploding star through a program called SPLASH. Once the 2-D method is satisfactory, we will consider ways in which to move to 3-D. [Preview Abstract] |
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J1.00010: A Singular Value Decomposition of 15MProgenitor Chimera Entropy Data Jesse Buffaloe, Brandon Barker, Eirik Endeve, Anthony Mezzacappa, Eric Lentz Core collapse supernovae are characterized by muti-dimensional dynamics. Studies have shown that the shock formed at core bounce always stalls. Until the development of axisymmetric (2D) simulations, little progress towards reviving the shock had been made. Modern simulations have given rise to the idea that both neutrino driven convection and the standing accretion shock instability (SASI) play pivotal roles in reviving the stalled shock. These mechanisms can increase the time material spends in the gain layer. The gain layer, the region near the stalled shock where net neutrino heating occurs, is dominated by turbulent flow. The turbulence in this region is necessary for maximizing the efficiency of the neutrino heating mechanism. Much of modern supernova theory is concerned with which of these two mechanisms plays a larger role in the revival of the stalled shock. We attempt to employ a singular value decomposition (SVD) in order to explore the relative contributions of the neutrino driven convection and SASI mechanisms. [Preview Abstract] |
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J1.00011: Image Reduction and Aperture Photometry of SN2011fe Phillip Rouse, Ginger Bryngelson The ultimate goal of this research was to calculate and plot data points along a light curve for type Ia supernova 2011fe, located 21 million miles away in the Pinwheel Galaxy. This was achieved through a two-step process of image reduction and aperture photometry. Image reduction is used to process the object images taken of the supernova over a certain time interval (usually over a single night) in order to correct for imaging errors. These corrections include fixing bad pixels, filtering out background noise, and correcting readout errors. Our images were taken with the MOSAIC Instrument on the 4-meter Mayall Telescope at the Kitt Peak National Observatory near Tucson, AZ using observing time granted by the National Optical Astronomy Observatory. Photometry is used to measure the luminosity output or ``flux'' of supernovae and stars over an interval of time. This is done for multiple bands of optical light, and the data is used to plot points on a light curve, which shows the luminosity of the star as a function of time. Though we are typically focused on later times, my data focuses on earlier periods in the supernova's luminous progression. [Preview Abstract] |
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J1.00012: Investigation of radio signals from Sun and Jupiter using radio JOVE antenna. Rajeeb Sharma, Suyogya Karki, Nicholas Lemoine, Sanichiro Yoshida A Radio JOVE Antenna has been setup to monitor the radio signals received from the Sun and Jupiter. The setup uses a dual-dipole, phased arrangement of the antenna and has been configured to operate at a frequency of 20.1 MHz. The antenna is connected to the receiver with 133.68 ft (3.5 $\lambda $ of the radio signal) of RG-6 coaxial cable resulting in 1.12 dB attenuation of the signal received. The incoming radio waves generate a voltage in the antenna which is configured as change in temperature from the cosmic background temperature. This change in temperature is recorded and archived using the Radio-Skypipe software in Coordinated Universal Time (UTC). Data collected by the software is converted into frequency domain using Fourier transform functions and analyzed using MATLAB. Analyzing the peaks observed in frequency domain makes it easier to separate the required signals from other background interferences. Although no major signals from the Sun or Jupiter have been observed, various natural and man-made interferences have been successfully identified and recorded. [Preview Abstract] |
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J1.00013: Five Open Astrophysical Questions Florentin Smarandache \textbf{\textit{1.}} As a generalization of the Pure Gravitational Field, is it possible to have a Pure Magnetic Field, or Pure Electric Field, or Pure Electromagnetic Field, etc. without matter in its proximity? \textbf{\textit{2.}} If a star explodes or is destroyed or dies, what happens to the planets that orbit it? Will they continue to orbit by inertia the point where the star used to be? For how long time? \textbf{\textit{3.}} Is there a beginning and ending of time? Or is the time an entity without ending or beginning? We dough the Big Bang Theory that asserts a \textit{creatio ex nihilo} of the Universe. If it was a point in the Big Bang that exploded, where did this point come from? What was before that point? \textbf{\textit{4.}} Massive cosmic bodies create gravity. Is there a bound for such cosmic bodies (depending on mass, volume, density, and may be position) starting from which cosmic bodies create gravity, while below that bound they don't create gravity? \textbf{\textit{5.}} We do not agree with the Lorentz Relativity and the Lorentz Ether Relativity that support superluminal speeds up to a limit of \textit{2c}, although the absolute velocities are added using normal arithmetic in these two Relativities. We think there can be constructed speeds that overpass \textit{2c} as well. [Preview Abstract] |
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J1.00014: Cosmological Renormalization Group Equation and the Scale Dependence of Cosmic Voids Eric Steinfelds, Keith Andrew, Thad Roberts, Curtis Poland The large scale structure of the galaxy distribution in the cosmic web is often characterized by the two point correlation function. Recently general two point correlation analysis has been extended from galaxies to quasars, clusters, halos and voids. However, the two point function is just the first in an infinite series of the full n-point correlators needed to understand the details of large scale cosmological structure. It has been found that for a certain range of scales the distribution of matter and of voids exhibits a self-similar pattern. As noted by Peebles, the Renormalization Group Equation (RGE) can be used to study large scale structure from a different perspective involving self-similar patterns. The RGE can be effective for identifying patterns that appear at multiple length scales such as those in a multifractal structure. Here we apply the multifractal method to SDSS, CfA, 6dFGRS, WiggleZ and n body hierarchical numerical simulations from Gadget II. We find the singularity spectrum for a dual mulitfractal void structure that has an asymptotic RGE homogeneity scale on the order of 390h$^{\mathrm{-1}}$ indicating there can be a very large nearly uniform matter distribution similar to the Cosmological Principle used in FRLW cosmological models. [Preview Abstract] |
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J1.00015: Quantum Field Vacuum Effects on Causality, Focusing and the Penrose-Hawking Singularity Theorem to One Loop Eric Steinfelds, Keith Andrew, Thad Roberts Quantum field interactions alter the structure of spacetime through vacuum polarization effects in such a way that the changes can often be modeled with an effective spacetime index of refraction. This index couples directly to the scalar and Ricci curvatures of the manifold and will alter the null geodesic structure of the spacetime manifold and thereby the causal structure of events. This is manifested through the action of conjugate points and the energy conditions resulting in changes in the focusing of null rays and the formation of closed trapped surfaces. However, the underlying focusing structure is a critical ingredient in order for the Penrose-Hawking singularity theorems to apply. Here we use the results of Hollowood and Shore with the Drummond-Hathell action applied to a scalar field coupled to gravity to examine the ingredients of the singularity theorems including the vacuum effects at the one loop level within the context of a static elliptical Reissner-Nordstrom electric and magnetic monopole charged black hole metric. We find the expression for the change in null ray paths for a closed trapped surface for this metric and express this as changes in the causal structure as it impacts the event horizon and Cauchy horizon for this metric. [Preview Abstract] |
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J1.00016: How to Compute the Mass of a Singularity Point? Florentin Smarandache Considering the Black Hole's singularity that occurs for r $=$ 0, representing, according to the relativists, an infinitely dense point-mass that is at the center of the Black Hole. It is not clear how to compute the mass of this singularity, since Mass $=$ Volume x Density $=$ 0 x $\infty $ $=$ 0, $\infty $, or another value? Another uncertainty arises when calculating particular cases of what relativists considers as Schwarzschild radius of a Black Hole, or the radius of the event horizon. What about a cosmic body whose escape speed would be greater than the speed of sound (instead of the speed of light)? Therefore, no sound would come out from that body, so it would be labeled as ``mute body''! [Preview Abstract] |
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J1.00017: Spectroscopy with Cold, Trapped Ions Kevin Ferri, Jeremy Glick, Jaclyn Schmitt, Joshua Hanson, 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. Two apparatuses optimized for the study of single charged and highly charged ions are being developed. Singly charged atomic and molecular ions in rf traps will be used to study the dynamics of state to state chemical reactions and chemistry relevant to astrophysical systems. Highly charged ions from the Clemson University EBIT (Electron Beam Ion Trap) will be used to probe atomic systems under the conditions of extreme electric fields. This poster will present an update on the experimental progress on these two apparatuses. [Preview Abstract] |
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J1.00018: Design and Construction of Anti-Helmholtz Coils for Laser Cooling and Trapping Gd Upendra Adhikari, Clayton Simien Lanthanide elements are of interest because of their potential for investigating next generation optical clock transitions, novel non-S ground state ultracold collisions, and the physics of quantum degenerate dipolar gases. We present the design and construction of Anti-Helmholtz coils for the laser cooling and trapping of atomic Gadolinium (Gd). The design, construction, and performance of the apparatus will be presented. [Preview Abstract] |
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J1.00019: Measuring the Polarization State of a Beam of Individual Photons Cody McKenzie, Preston Alexander, R. Seth Smith During the past three 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 project, coincidences were detected between pairs of single photons and this data was used to determine the polarization state of a beam of individual photons, including all of the coefficients that describe the quantum state of the photons. This experiment was performed for linear, circular, and elliptical polarization states. The theory, experimental setup, procedure, and results will be presented. [Preview Abstract] |
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J1.00020: Construction of a Progressive Lens with an aspheric carrier using a Freeform Lens generator Mario Carcamo Progressive lenses are a very commonly used multifocal lens in which the lens power transitions between two values while keeping the transition area on the surface smooth. The final surface design of a progressive lens is typically solved for using numerical methods. An aspheric lens is another type of lens that aims to make a slimmer design than their perfectly spherical counterpart and usually used to make high powered lenses. I present an algorithm in which you can take an existing progressive surface and add to it an aspheric treatment to make a progressive that is slimmer than its non-aspheric counterpart while still achieving high quality optics. The software that was made that employs the algorithm was designed to produce a surface to be made by a Freeform lens generator. The quality of the optics was determined by its deviation from its spherical counterpart ensuring no more than a 0.12 diopter difference inside a given optical zone. [Preview Abstract] |
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J1.00021: Synthesis of Novel Bi/Sb Modified Chalcogenide Glasses Travis Hodge Chalcogenide glasses (ChG) are considered as the most convenient and inexpensive media for applications in modern photonics, combining high IR transparency, excellent fiber drawing capability and largest optical nonlinearities reported to date. The Bi$_x$(GeSe4)$_{33.3 - x/3}$(GeTe4)$_{33.3 -x/3}$ \\ (GeS4)$_{33.3 - x/3}$ (x=0,1,5), Bi$_x$(GeSe4)$_{60 - x/3}$(GeTe4)$_{20 -x/3}$(GeS4)$_{20 - x/3}$ (x=0,1,5) and Bi$_x$Ge$_{20}$Sb$_{20 – x}$Se$_{20}$S$_{20}$Te$_{20}$ (x=0,1,5) chalcogenide systems were examined in order to form bulk glasses by conventional melt-quench method. The optimal conditions for the obtaining amorphous samples have been worked out. Obtained glasses were characterized by X-ray Diffraction (XRD) and thermal analysis techniques. [Preview Abstract] |
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J1.00022: Accessible Hong-Ou-Mandel Measurements of Frequency-Entangled Light Amos Manneschmidt A technology for reliably generating entangled photon pairs would greatly help other emerging technologies, such as quantum key distribution and optical computing. We sought to analyze the entanglement of photons correlated across their frequency degree of freedom. This avenue of research is warranted because traditional means of creating joint spectral probability distributions require continuous time tagging superconducting nanowire single photon detectors (SNSPDs), in conjunction with low-jitter time-of-arrival electronics. This method instead uses standard InGaAs avalanche photodetectors (APDs) to create a joint spectral probability distribution from photon pairs generated via downconversion processes in a non-linear media waveguide. In this setup, the sum of two entangled photon energies will exactly equal the energy of the incident pump photon. By launching the downconverted photons into a Hong-Ou-Mandel interference setup consisting of hundreds of meters of fiber optic cable, pair separation is achieved; individual photon arrival times are correlated to energy. By selecting the proper length of cable, g$^{2}$, can be measured to indicate downconversion efficiency. [Preview Abstract] |
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J1.00023: Thermally-induced optical bistability and temperature broadening of spectroscopic bands in Cr:ZnSe and Fe:ZnSe mid-IR laser materials. Chandler Bernard, Rick Watkins, Ozarfar Gafarov, Vladimir Fedorov, Sergey Mirov Cr:ZnSe and Fe:ZnSe chalcogenides are well established materials for mid-IR laser applications in the 2-6 $\mu $m spectral range. We report on the characterization of the absorption cross sections at $^{\mathrm{5}}$T$_{\mathrm{2}}\leftrightarrow^{\mathrm{5}}$E laser transition in the 77K-389K temperature range for these crystals. The obtained results allowed us to model thermally-induced optical bistability under pump radiation. For Cr:ZnSe, it was found that the position of the peak of the absorption coefficient shifted from 1770 to 1750 nm and its value decreased to 88{\%} of the RT value when the crystal's temperature was increased from RT to 389 K. At wavelengths of 2040 nm and 1650 nm, it was observed that the increase in temperature from RT to 389 K did not induce change in absorption. The maximum change of the absorption cross-sections of $\sigma^{\mathrm{-1}}$d$\sigma $/dT $=$ -1.6 X 10$^{\mathrm{-3}}$ K$^{\mathrm{-1}}$ and $\sigma^{\mathrm{-1}}$d$\sigma $/dT $=$ 2.9 X 10$^{\mathrm{-3}}$ K$^{\mathrm{-1}}$ were measured at 1830 nm and 1530 nm respectively. The developed model predicts thermally-induced optical bistability under absorbed pump power \textgreater 20W in the 3 mm long gain elements. This effect should be considered in the development of a high power laser system. It could also be used for temperature control of lasing parameters. [Preview Abstract] |
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J1.00024: Atomic Physics Uncertainties on Plasma Spectral Diagnostics Zechun Yang, Michael Pindzola, Randall Smith, Adam Foster, Connor Ballance, Robert Sutherland, Stuart Loch Spectral diagnostics of astrophysical plasmas represents one of the main sources of information on those object. These diagnostics, such as using a line intensity ratio to determine plasma electron temperature, usually do not allow for the effect of uncertainties in the atomic rate coefficients. We present methods to assign baseline uncertainties on the electron-impact excitation, ionization, and recombination rate coefficients. These are propagated through a collisional-radiative model to produce uncertainties on the well know G and R-ratios for a He-like system. In this way, a range of values can be placed on the diagnosed temperature and density of a plasma. [Preview Abstract] |
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J1.00025: Creating a C$++$ Package to Build and Solve Electron Population Evolution Equations of Rubidium and its Isotopes in the Context of Laser-Atom Interactions. Daniel Keylon, Brett Depaola In Atomic, Molecular, and Optical Physics, researchers often study light-matter interactions. Lasers are used to probe the energy structure of atoms to determine relative electron populations. However, experiments can be time consuming to set up with parameters that are difficult to vary during runtime. The goal of this project is to build a software package to autonomously build and solve the theoretical equations that predict population evolution. This software can be used to quickly test different experimental setups and identify experimental parameters that could produce interesting results. The initial version of this program focuses on solving the population evolutions of Rubidium and Rubidium isotopes. [Preview Abstract] |
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J1.00026: Colorimetric Flocculation and SERS of Molecule-Linked Gold Nanoparticles Anderson Hayes, Quinton Rice, Bagher Tabibi, Jaetae Seo The colorimetric flocculation and surface-enhanced Raman scattering (SERS) of molecule-linked plasmonic nanoparticles have recently brought great attentions in the biomedical application. In biomedical application, the early detection of diseases or unhealthy cells through molecule identification with significant low limit-of-detection is considered as an essential component of successful medical treatment. The common optical techniques for biomedical applications include the fluorescence with single- or two-photon excitation, and Raman scattering. The molecule fluorescence with either single photon or two photon excitation has been widely used for biomedical sensing and molecule identification because of the large fluorescence cross-section of molecules. The Raman scattering provides the molecule finger-prints that allow to identifying the molecules related to the diseases and unhealthy cells. This presentation will include: the colorimetric flocculation of synthetic urine-linked plasmonic nanoparticles; the vibration frequency shift of molecule, and the selective enhancement or quenching of Raman scattering under the localized-plasmonic field; and the coherency between plasmonic mode and vibration mode of the molecule-linked colloidal nanoparticles. [Preview Abstract] |
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J1.00027: \textbf{Roco4 kinase crystal structures fail to capture expected dynamical behavior of LRRK2, a protein implicated in Parkinson's disease} Sirui Ma, Hector Velazquez Leucine-rich repeat kinase 2 (LRRK2) is a multi-domain protein implicated in Parkinson's disease (PD). Understanding LRRK's contribution to pathogenesis requires study of the kinase domain. Unfortunately, such studies are complicated by the unavailability of LRRK2 crystal structures. Previous studies have shown that humanized Roco4 kinase may be a suitable surrogate for LRRK2 in chemical investigations. Our study assesses the dynamical behavior of humanized Roco4, compared to that of a homology model, by molecular dynamics simulations. We attempt to capture conformational changes of the activation loop from active to inactive forms, a key feature in the regulation of LRRK2 kinase activity. Our results indicate that simulations of humanized Roco4 fail to capture these conformational changes. Such a finding suggests that Roco4 may not be a suitable model for computational LRRK2 studies. We intend to conduct additional studies to further elucidate Roco4's performance as a LRRK2 mimic, though our initial results call into question its viability. A validated LRRK2 model is crucial for the development of drugs that can treat or even cure PD, and predictions of increasing disease frequency further compound the importance of LRRK2 research. [Preview Abstract] |
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J1.00028: Characterization of Simulated Martian Nanocomposites with Alkali Perchlorate Salts Calrissa Roe, Brittany Broder, Ed Kintzel, Keith Andrew, Shane Palmquest, Melinda Thomas As NASA is preparing for a manned mission to Mars in the 2030's, there is intense interest in the development of simulated Martian materials. Our team has synthesized novel simulated Martian cementitious materials, which incorporated carbon nanomaterials as well as alkaliearth and alkali-metallic salts. These chlorate and perchlorate salts are consistent with those found in the geologic recurring slope linnae on Horowitz crater identified as a source of Martian water. The synthesized cements have the potential to be stronger, lighter weight, and more durable, which is of keen interest to manned Mars mission specialists. Sample characterization has used a combination of real space surface imaging at the NOVA Center using the Large Chamber Scanning Electron Microscope, elemental analysis using Energy Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), and Tip Enhanced Raman Spectroscopy (TERS). In combination with imaging, \textit{in-situ} load frame measurements are carried out to compare the relative strengths of these prepared materials. A NASA goal is the development of the correct nanocomposites mixture that can subsequently be made by a surface robot sent to Mars several months prior to a manned landing for fabricating surface construction materials. [Preview Abstract] |
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J1.00029: Effect of pulsed laser deposition parameters on nanocrystalline grain orientation in barium zirconate for fuel cell applications. Eric Remington, Alex Skinner, Patrick Kung, Renato Camata Solid oxide fuel cells rely on thermally activated conduction of ions through an electrolyte material. Barium zirconate doped with various group III transition metals is predicted to offer improved ionic conductivity at intermediate temperatures (500-700$^{\circ}$C) than conventional yttria-stabilized zirconia-based electrolyte materials. We have synthesized thin films of barium zirconate doped with gadolinium by means of pulsed laser deposition. Films were deposited using a KrF excimer laser on Pt substrates at 850$^{\circ}$C in a background pressure of 50 mtorr of oxygen from targets prepared in-house by mixing barium zirconate and gadolinium oxide powders. X-ray diffraction studies suggest that preferential crystallographic orientation increases by decreasing target to substrate distance and laser fluence. Preferential crystallographic orientation may lead to improvement in conductivity as measured by impedance spectroscopy. [Preview Abstract] |
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J1.00030: Improve the 4H-SiC/SiO2 interface quality through plasma annealing treatment Maurice McGee, Zengjun Chen Silicon Carbide (SiC) is a wide band-gap semiconductor material with broad applications in the technological realm. Its high thermal conductivity, high breakdown field, and high electron mobility make it beneficial for use in electronic devices that operate at high temperatures and high voltages. However, SiC does have limitations. One can be found at its interface with silicon dioxide (SiO2), where many defects are present. The higher the defects density, the more resistance there is for the electrons to flow freely. Consequently, the flow of electrons of the SiC-based devices has become greatly restricted. As a result of this, much effort has been done on reducing the defects density at the interface. In the present work, the plasma annealing allows us to incorporate nitrogen at the SiC/SiO2 interface. It is still not fully understood how nitrogen improves the interface, but the experiments have shown that the plasma annealing treatment significantly decreases the defects density. It is also shown in our results that the amount of incorporated nitrogen is positively related to the reduction of the defects density. Further experiments will be carried out to study the relationship between the plasma annealing and channel mobility enhancement in MOSFETs. [Preview Abstract] |
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J1.00031: Wide PL spectra of plasmon-coupled CdSe QDs for hybrid white LEDs Quinton Rice, Anderson Hayes, Sangram Raut, Rahul Chib, Zygmunt Gryczynski, Ignacy Gryczynski, Andew Wang, Bagher Tabibi, Jaetae Seo Plasmonic coupling of CdSe quantum dots (QDs) has been extensively studied due to their many benefits to the field of optoelectronics including wide optical tunability, high color purity, and large PL enhancement in the vicinity of plasmonic nanoparticles. The fluorescence of CdSe QDs originates from exciton carrier recombination, whereas discrete energy states and blue-shift from the bulk bandgap (\textasciitilde 718 nm) arises from quantum confined carriers when the QDs are near the exciton Bohr radius (\textasciitilde 5.8 nm) in bulk. Inclusive analysis of the major emission sites revealed the band-egde and surface-trapped state transitions to be the principal contributors to the PL while the studies of plasmon-exciton coupling elucidated the reduction of nonradiative transition and PL enhancement with the strong local field. The time-resolved spectroscopy revealed the decay rates of bandedge and surface-trapped states, and the temperature-dependent PL studies explained the thermal quenching of QDs with/without plasmon coupling. The hybrid white LED is realized with the spectral combination of blue LED excitation, intermediate spectrum from bandedge transition, and broad spectral distribution of surface trapped state in addition to the large PL enhancement through plasmon-exciton coupling. [Preview Abstract] |
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J1.00032: Size Independent Glass Transition of Polystyrene Nanospheres Nicole Sikes The effect of confinement on the glass transition temperature (T$_{\mathrm{g}})$ has been studied in thin films, nanocomposites, and nanoparticles. Keddie et al studied T$_{\mathrm{g}}$ as a function of film thickness and found that while T$_{\mathrm{g}}$ decreased with decreasing film thickness when the film was on a gold substrate, there was an increase in T$_{\mathrm{g}}$ with decreasing film thickness when the film was on silicon substrate. Thin films are a popular system to study; however understanding other systems is crucial to understanding the fundamental effects of confinement. Polymer nanoparticles are an attractive system due to their potential as drug delivery agents, however the studies on them are limited and the results are in poor agreement. However most researchers have claimed to find that Tg is dependent on the size of the nanoparticles. Here temperature-varied fluorescence spectroscopy was used to study the glass transition temperature of polystyrene nanospheres of varying sizes (including sizes far below what has been actively investigated in the literature) and anomalous size independent T$_{\mathrm{g}}$ for particles below a certain size was found. [Preview Abstract] |
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J1.00033: An Analysis of Structural Changes of Glassy Arsenic Selenides due to Ga and Te Incorporation Caithleann Thomas, Roman Golovchak, Himanshu Jain, Yaroslav Shpotyuk Structural changes of As2Se3 due to the incorporation of Ga and Te are studied using X-ray photo-electron spectroscopy(XPS), extended X-ray absorption fine structure (EXAFS) and Raman techniques. Mostof the As, Se and Te atoms build a covalent network according to their main valences. Three-fold coordinated As atoms form pyramidal structural units, which are connected via bridges of two-fold coordinated chalcogen atoms (Se, Te).On the other hand, coordination of Ga in glassy samples is found to be greater than three, as expected from its valence, increasing with Te content. Some of the As atoms appear to be converted into four-fold coordinated state at low Te concentration, while a fraction of Te and, possibly, Se atoms are thought to exist in a singly-coordinated (terminal) state in the vicinity of Ga in the samples with higher Te concentration. [Preview Abstract] |
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J1.00034: \textbf{Photoresponse of Thermally-Deposited and Spin-coated As}$_{\mathrm{\mathbf{2}}}$\textbf{S}$_{\mathrm{\mathbf{3}}}$\textbf{ Chalcogenide Glass Thin Films} Joshua Allen, Cameron Johnson, Leo Saturday, Cathleann Thomas, Justin Oelgoetz, Andriy Kovalskiy Chalcogenide glass thin films are known as promising materials for optical recording, photonics and other applications which require substantial photoinduced optical effects in UV-VIS region. However, some applications such as non-linear optical elements in the IR region of spectrum prefer thin film materials with stable optical properties in the visible range. Spin-coating technology for fabrication of As$_{\mathrm{2}}$S$_{\mathrm{3\thinspace }}$thin layers stable to the influence of visible light in wide intensity range was developed. The photoinduced effects in thermally deposited and spin-coated films were compared. It was shown that the position of the absorption edge of spin-coated samples does not change up to the intensities of LED light close to 160 mW/cm$^{\mathrm{2}}$. Raman studies of photoinduced structural transformations in both thermally deposited and spin-coated layer were studied. Structural stability of glass matrix for the spin-coated layers was confirmed. Computational model of the photostructural transformations is presented for the thermally deposited films. [Preview Abstract] |
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J1.00035: Study of bond length as a function of basis set and density functional for As$_x$S$_y$ glasses Laura Judy, Justin Oelgoetz As$_x$S$_y$ glasses are used in variety of applications ranging from optical fibers to optoelectronics. Thin films of these materials are known to undergo structural changes when exposed to above-bandgap light as well as $\gamma$-radiation. In order to model these effects, one must first establish a validated model which is based on a particular basis set and density functional. This poster presents the results of an ongoing numerical study on the effect of basis set and density functional choice on the bond lengths and angles of AsS clusters, much like what one might find in a As$_x$S$_y$ glass. Geometry optimization calculations carried out in NWChem using a variety of Pople type (6-311G, 6-311G*, etc.) and Dunning type (cc-pvdz, cc-pvtz, aug-cc-pvdz, aug-cc-pvtz, etc.) basis sets in combination with various density functionals (b3lyp, pbe0, becke88 perdew86, m06, m11, etc.) are being considered. Comparisons of the structural parameters across the calculations as well as comparisons to experimental results will be presented. [Preview Abstract] |
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J1.00036: Thermal Analysis of Bi/Ga Doped Germanium Chalcogenides Leo Saturday, Cameron Johnson, Roman Holovchak, Yaroslav Shpotyuk Bi and Ga doped chalcogenide glasses (ChG) have several potential applications in modern photonics and optoelectronics. In addition, ChG can be used in phase-change memory material, since they possess rapid phase change between amorphous and crystalline states. In this work, we have investigated the glasses of Bi$_{\mathrm{x}}$Ga$_{\mathrm{y}}$(GeSe$_{\mathrm{4}})_{\mathrm{50-(x+y)/2}}$(GeTe$_{\mathrm{4}})_{\mathrm{50-(x+y)/2}}$ family with thermal analysis techniques in order to determine crystallization kinetics and Index of Crystallization Rapidity (ICR) for major phases. These ICR rates suggest further potential uses for this glass family in phase change memory storage. The X-Ray Diffraction (XRD) Spectroscopy also gives a look at the specifics of this material's crystalline compounds. [Preview Abstract] |
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J1.00037: Spin-Coating and Characterization of Chalcogenide Glass Thin Films Cameron Johnson, Leo Saturday, Roman Golovchak, Andriy Kovalskiy Spin-coating is a method to produce thin films of materials that is quite simple and provides fairly high quality. In this work the process of spin-coating for different chalcogenide glasses such as As2S3, As2Se3, and GeS is investigated and discussed. The mechanism of spin-coating for As2S3 is relatively well understood. Our goal is to investigate the effects the different variables of spin-coating have on the final film quality and performance. At the same time, very little investigation has been done on the spin-coating or even the dissolution of As2Se3 and almost none on GeS2 and GeSe2 glasses. It was found that spin-coating As2Se3 is much more challenging than As2S3 due to a variety of factors and the usual methods applied for arsenic sulphides are not as effective for As2Se3. It is also seen that the quality of the films of GeS(Se)2 produced using our methods are very low, necessitating the use of a different approach. The thermal properties of As2S3 thin films produced by thermal evaporation and spin-coating were also investigated using a Differential Scanning Calorimetry method to find if annealing has any effect on the glass transition temperature and crystallization. [Preview Abstract] |
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J1.00038: Thickness dependence of critical current density in RABiTS coated conductors. A J Brady, J L Brownlee, R Feenstra, A O Ijaduola The critical current density $J_c$ flowing in thin $YBa_2Cu_3O_{7-\delta}$ (YBCO) films of various thicknesses $d$ has been studied magnetometrically, both as a function of applied field $H$ and temperature $T$. The films, grown by a BaF2 ex-situ process and deposited on buffered `RABiTS' substrates of Ni-5W, have thicknesses ranging from 28 nm to 1.5 $\mu$m. The $J_c$ increases with thickness at first, peaks at about d $\sim$ 120 nm, and decreases with thickness thereafter. In intermediate applied magnetic fields, we find a power law falloff $J_c \propto H^{-\beta}$ with $\beta$ $\sim$ (0.56 - 0.69) for all the samples. Temperature dependence of the $J_c$ is also studied. [Preview Abstract] |
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J1.00039: Carrier Concentration Control for n-Type Conductivity in Mid-Infrared Active Cr2$+$:ZnSe Thin Film Structures Matthew Rhoades, Zachary Lindsey, Vladimir Fedorov, Sergey Mirov, Renato Camata Mid-infrared (IR) stimulated emission under optical excitation has been demonstrated in chromium doped zinc selenide (Cr2$+$:ZnSe) thin films. Achieving this in an electrically excited structure would have numerous applications. This goal requires careful control of carrier concentration (ND) in the n-type and p-type layers adjacent to the mid-IR optically active material, which is made difficult by the highly insulating characteristics of Cr2$+$:ZnSe. In this work thin films of chlorine doped zinc selenide (Cl:ZnSe) are fabricated with pulsed laser deposition (PLD) to function as n-type cladding layers in a heterostructure for mid-IR electroluminescence. An effective n-type doping of ZnSe is achieved by varying the mass ratio of zinc chloride (ZnCl2) to ZnSe precursors in the starting pressed powder targets. Appropriate stoichiometric mixtures allow for the control of the ND in the Cl:ZnSe targets that are used to produce thin films on gallium arsenide substrates by PLD. Impedance spectroscopy, specifically the Mott-Schottky measurement, is used to determine the ND of the fabricated thin film samples. We will discuss the observed correlation between ND determined from the stoichiometric mixtures of ZnCl2 to ZnSe and the measured ND in post-PLD thin films. This will allow for ND to be controlled in Cl:ZnSe thin films to be used as n-type layers in Cr2$+$:ZnSe structures capable of electrically pumped mid-IR stimulated emission. [Preview Abstract] |
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J1.00040: Gadolinium-doped Barium Zirconate Thin Films on Barium Zirconate/Nickel Cermets for Applications in Intermediate Temperature Solid Oxide Fuel Cells Alex Skinner, Kelly Dillon, Eric Remington, Renato Camata Solid oxide fuel cells (SOFCs) are electrochemical devices that convert chemical energy into electricity using ion-conducting oxide ceramics as electrolytes. Thin films of gadolinium-doped barium zirconate (BZG) have been developed in our lab, and have the potential to lower SOFC operating temperatures. A suitable substrate and anode material is needed for the deposition of these films. Barium zirconate/nickel cermets were fabricated from barium zirconate and nickel oxide powders. Samples were mechanically mixed, pressed into pellets and annealed at 1400\textdegree C. Reduction of these cermets was then carried out in a hydrogen-containing atmosphere at 650\textdegree C to reduce the nickel oxide to nickel metal, making them conductive. Pulsed laser deposition (KrF; 0.5-1 J/cm$^{\mathrm{2}})$ was used to deposit BZG as thin films on various cermets in a 20-100 mTorr oxygen environment and at a temperature of 850\textdegree C. Electrical measurements were taken of the samples using an electrochemical impedance spectroscopy (EIS) system and compared to the cermets prior to deposition. X-ray diffraction measurements are used to study the crystallinity of the films deposited on the cermets in comparison to results obtained on other conventional substrates such as MgO and platinum. [Preview Abstract] |
(Author Not Attending)
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J1.00041: The Effect of Impurities on the Superconductivity of BSCCO-2212 John Vastola BSCCO-2212 is a high-temperature cuprate superconductor whose electronic structure is currently poorly understood. In particular, it is unclear whether its order parameter is consistent with s-wave or d-wave behavior. Leggett has suggested that its order parameter might take a certain form that is consistent with d-wave behavior. While some experiments on the surface of BSCCO seem to support this conclusion, other experiments have suggested that its order parameter is instead s-wave in the bulk. We present some quantum field theoretic calculations in the spirit of Abrikosov and Gorkov's approach to the theory of superconductivity that suggest that such an order parameter cannot be correct. We will demonstrate that having such an order parameter would mean that BSCCO's critical temperature would go to zero if it is sufficiently impure, contradicting experimental evidence otherwise. These calculations lend support to the hypothesis that BSCCO is an s-wave rather than a d-wave superconductor. [Preview Abstract] |
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J1.00042: Full analytical Expressions of the Quantum Mechanical Energy Eigenstates of charged Particles confined in a Penning Trap at non-relativistic Energies. Eric Steinfelds, Keith Andrew The storage of a few charged particles at low kinetic energy and at higher energies can be estimated by finding and characterizing the trajectories of charged particles which are classically bound within a Penning trap. However, there is benefit to using quantum mechanics to predict the energy levels and to map out the probability distributions of a few charged particles such as e`s and protons which are `trapped' in a given Penning Trap with particular settings for Bo (magnetic field) and quadrupole `E'strength (Vzz$_{\mathrm{[qua]}})$. We are able to analytically solve the Schr\"{o}dinger equation which represents the Hamiltonian of a single charged particle confined in a Penning `device'. Presuming that the L$_{\mathrm{[orbit]}}$ and `longitudinal' kinetic energies are non-relativistic, then the eigenvalues of the possible energies of the single charged particle follows a formula for ``QM'' integers $N$ and $m$: E$_{\mathrm{(N,m)}} \quad =$ 2*$\hbar $/$_{\mathrm{M}}$*G*(N$+$1) -m*$\hbar $*q*Bo/$_{\mathrm{M}}$, where G$=$ sqrt(q$^{\mathrm{2}}$*Bo$^{\mathrm{2}}$/4 -M/$_{\mathrm{2}}$*q*Vzz$_{\mathrm{[qua]}})$ . This work matches the formulation the famous QM text [1]. On the other hand, ref[1] allows B$_{\mathrm{o}}$ but not Vzz$_{\mathrm{[qua]}}$. \\ \\ Bibliography:\\ $[1]$ L. Landau and E. Lifshitz, "Quantum Mechanics – Course of Theoretical Physics", Volume 3-Third Edition, Pergamon Press, © 1977. [Preview Abstract] |
(Author Not Attending)
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J1.00043: Determination of Target Cell Window Thickness Using X-Ray Attenuation. Mikhail Gaerlan, James Dunne, Ronald Unz This project aims to use x-rays produced from a radioactive Am-241 source to measure the thickness of the target cell window used in the recently completed Qweak experiment at the Thomas Jefferson National Facility Accelerator in Virginia. The aluminum windows that will be measured are very thin, on the scale of a tenth of a millimeter. The advantage of using x-rays to measure thickness is that the measurement requires minimal physical and mechanical interference with the material and should be capable of sub-1{\%} accuracy on the thickness measurement. Reducing this uncertainty on the window thickness is very important to the Jefferson Lab Qweak final result. In addition, one could consider this project as a seed program to building the capacity at MSU to potentially measure all future target windows for Jefferson Lab experiments. [Preview Abstract] |
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J1.00044: Test and Calibration of the Pair Spectrometer Detectors at the Jefferson Laboratory Gregory Terlecky, Christopher Dolan The pair spectrometer is a key instrument used to monitor the quality of the photon beam in Hall D at Jefferson Lab. We spent two months in summer 2015 working on the pair spectrometer with a focus in two areas: (1) to test high granularity hodoscopes, (2) to perform the timing calibration by analyzing experimental data collected in the spring 2015 from the commissioning runs. The results and our research experiences will be presented. [Preview Abstract] |
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J1.00045: Calibration of the HMS Scintillators in Hall C at Jefferson Lab. Maria Manrique, Simona Malace, Jonathan Castellanos, Mark Jones, Erik 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. 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 $^{\mathrm{60}}$Co source to insure 100{\%} detection efficiency for the particles of interest. [Preview Abstract] |
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J1.00046: To Understand the Mechanisms of Hadro Production in t-channel Dependence Daniel Puentes, Brian Raue, Lei Guo, Shankar Adhikari, Maria Manrique Studies of hadron photoproduction in the past few decades have yielded tremendous amounts of information. The wealth of data allows us to understand which exchange mechanisms result in production of specific hadrons. This can be investigated by studying how, at low momentum transfer, the t-dependence of the differential cross section changes with the photon beam energy. Studying the t-dependence allows us to probe into the nature of the different exchange particles at different energies. Multiple reactions are being studied to better understand how the t-dependence varies among different hadron production reactions. Some reactions being studied include $\gamma \text{p} \rightarrow \text{K}^{+} \Sigma^{0} $ and $\gamma \text{p} \rightarrow \text{p} \omega $ for a preliminary investigation. [Preview Abstract] |
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J1.00047: Pulsed laser deposition of ZnS$_{x}$Se$_{1-x}$ and its integration into multilayered Cr$^{2+}$:ZnSe structures for mid-IR electroluminescence Z.R. Lindsey, M.W. Rhoades, V.V. Fedorov, S.B. Mirov, R.P. Camata Transition metal-doped II-VI semiconductor thin films have shown to be promising materials for mid-infrared (mid-IR) laser sources. When ZnSe is doped with transition metal ions such as Cr$^{2+}$, the resulting broad emission characteristics in the 2-3 micron spectral range indicate potential for tunable lasing in the mid-IR. However, the incorporation of Cr$^{2+}$ into the ZnSe lattice greatly decreases the conductivity of the material, which presents challenges for potential electroluminescence and device applications. A major goal of this work is to demonstrate electron flow through the optically active material by utilizing ultrathin Cr$^{2+}$:ZnSe sandwiched between conductive high-quality ZnSe-based layers. A p-n junction surrounding the Cr$^{2+}$:ZnSe layer is formed by pulsed laser deposition of the ternary alloy, ZnS$_{x}$Se$_{1-x}$, doped with appropriate n-type and p-type dopants, where the compositional parameter, x, is varied within the range x$=$0.02-0.10. Several films were deposited at varying growth temperatures and with various compositional parameters, and then analyzed via x-ray diffraction, scanning electron microscopy, and Raman spectroscopy to investigate and optimize the crystal quality of the alloy for device integration. An interesting growth regime is identified at a laser fluence of 1.8 J/cm$^{2}$ and substrate temperature of 425C where polycrystalline ZnS$_{0.06}$Se$_{0.94}$ grows on GaAs substrates with the (311) direction of the grains preferentially aligned along the direction normal to the substrate. [Preview Abstract] |
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J1.00048: Measurement of B Meson Decays to K*0 Gamma at the Belle II Experiment Steven Hinson, Romulus Godang We present a study of measurement of the exclusive branching fraction of B meson decays to K*0 Gamma at the Belle II Experiment. The K*0 Gamma meson decays to kaon and pion. The study is based on a simulated Monte Carlo data sample containing B meson pairs produced on the Upsilon(4S) resonance collected by the Belle II detector. The Belle II detector is located at the collision of electron-positron asymmetry-energy collider at the SuperKEKB storage ring facility in Tsukuba, Japan. [Preview Abstract] |
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J1.00049: Pion loop contribution to the nucleon self-energy interpolated between the instant form and the front form of relativistic dynamics Colton Bradley, Chueng Ji The equivalence of the light-front, equal-time and covariant formulations in meson-baryon interactions has been previously demonstrated. In particular, the self-energy of a nucleon dressed by pion loops with the pseudovector $\pi NN$ coupling has been discussed to show the universality of the leading nonanalytic behavior of the chiral dynamics consistent with QCD. In this poster, we present the link between the instant form dynamics and the light-front dynamics by interpolating them together with an interpolation variable. We confirm the universality of the leading nonanalytic behavior of the chiral dynamics by verifying the independence of this behavior from the interpolation variable. [Preview Abstract] |
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J1.00050: Preparations for upgrades to the level 1 track trigger at the Compact Muon Solenoid for the High Luminosity Large Hadron Collider Shaun Hogan, Eva Halkiadakis, Yuri Gershtein, Clare Shanahan Upgrades planned for the mid-2020's, designated the High Luminosity Large Hadron Collider (HL-LHC), aim to increase the luminosity (a measurement of how many proton-proton collisions occur in a given time) of the Large Hadron Collider by a factor of ten. With every event, data from the collision gets sent to a Level 1 (L1) Trigger within the Compact Muon Solenoid (CMS), which quickly analyzes whether the event contains useful information or not. With the implementation of the HL-LHC, the amount of data to be processed by the L1 Trigger will increase significantly, and new methods of processing information at this level will be required. Emulations of future L1 Track Trigger upgrades were tested with simulated data of pileup events to analyze the efficiency of detection algorithms. Furthermore, one particular search that will be conducted at the HL-LHC will be that of the Standard Model Higgs boson to light Higgs bosons. These light Higgs are predicted to decay into either of bottom quarks or tau leptons. Simulations of such events were generated, and subsequently analyzed in order to determine how these decays would appear within the detector, so that new detection algorithms may be created, and existing ones may be refined in order to look for signatures of new physical events. [Preview Abstract] |
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J1.00051: Colorblind-accessible, Sculptural Visual Aids For Math and Physics Caroline Bowen ~ ~ ~ ~ As a student, I am often frustrated by 3D mathematical objects presented through 2D means and the inherent loss of information about the object. To address this, I began designing physical visual aids of concepts in math and physics that are more mathematically explicit than traditional physics demos. This past summer I was inspired by examples in the online Mathematica documentation for the SliceContourPlot3D function to create the Plexiglass sculptures of different 3D functions that are the focus of this presentation. Two dimensional contour plots of 3D functions were generated in Mathematica, the contour lines were converted into paths, and the files were exported as .svg's to be processed in Adobe Illustrator for laser cutting the individual contour levels onto separate Plexiglass plates. The color schemes were created by analyzing a colorblind-accessible, continuous rainbow gradient in Adobe Illustrator to generate a set of ``base colors'' which were then entered into an online gradient generator to obtain a larger, banded gradient. Swatches were then printed and taken to a commercial house paint mixer to have custom paint colors mixed. After painting and drying drying, the plates were then mounted on rods with nylon spacers separating them. [Preview Abstract] |
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J1.00052: Pulsed laser deposition of ZnS$_{x}$Se$_{1-x}$ and its integration into multilayered Cr$^{2+}$:ZnSe structures for mid-IR electroluminescence Z.R. Lindsey, M.W. Rhoades, V.V. Fedorov, S.B. Mirov, R.P. Camata Transition metal-doped II-VI semiconductor thin films have shown to be promising materials for mid-infrared (mid-IR) laser sources. When ZnSe is doped with transition metal ions such as Cr$^{2+}$, the resulting broad emission characteristics in the 2-3 micron spectral range indicate potential for tunable lasing in the mid-IR. However, the incorporation of Cr$^{2+}$ into the ZnSe lattice greatly decreases the conductivity of the material, which presents challenges for potential electroluminescence and device applications. A major goal of this work is to demonstrate electron flow through the optically active material by utilizing ultrathin Cr$^{2+}$:ZnSe sandwiched between conductive high-quality ZnSe-based layers. A p-n junction surrounding the Cr$^{2+}$:ZnSe layer is formed by pulsed laser deposition of the ternary alloy, ZnS$_{x}$Se$_{1-x}$, doped with appropriate n-type and p-type dopants, where the compositional parameter, x, is varied within the range x$=$0.02-0.10. Several films were deposited at varying growth temperatures and with various compositional parameters, and then analyzed via x-ray diffraction, scanning electron microscopy, and Raman spectroscopy to investigate and optimize the crystal quality of the alloy for device integration. [Preview Abstract] |
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