Bulletin of the American Physical Society
Annual Meeting of the APS Four Corners Section
Volume 62, Number 17
Friday–Saturday, October 20–21, 2017; Fort Collins, CO
Session G1: Poster Session |
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Chair: Jean-Francois VanHuele, Brigham Young University Room: Lory Student Center Ballroom A/B |
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G1.00001: Speckle Interferometric Observation of WDS 14564$+$8503 Stephen White, Paige Benson, Sepehr Fard, Gezal Bahmani, Alexander Beltzer-Sweeney, Irena Stojimirovic, Richard Harshaw, Grady Boyce, Pat Boyce Speckle interferometric observations of the tertiary system WDS 14564$+$8503 were made in order to measure the position angle (theta) and separation (rho) of the AB component, and were found to be 291.516\textdegree \textpm 0.098\textordmasculine and 3.433'' \textpm 0.010'', respectively. The measurements showed a continuation of the linear motion trend, but were inconclusive in confirming whether or not the AB component is gravitationally bound. [Preview Abstract] |
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G1.00002: Effects of Sparse Data on the Inversion of Lightcurves for the 3D Modeling of Asteroids Sebastian Hendrickx-Rodriguez, Daniel Klinglesmith III The asteroid belt is estimated to contain over one million asteroids, but only a few hundred have a 3D model. Prior research has shown that the inversion of lightcurves is an effective method to obtain these models. However, it is time consuming to collect `dense' lightcurve observations where the time between data points is much less than the rotation period of the asteroid; especially because reliable shape models are only produced by observing an asteroid at several different solar bisector angles, a process that could take years and span several different geographical locations. Therefore, the use of `sparse' in time data, where data points are collected at a rate much slower than the rotation period of the asteroid, is becoming increasingly popular for the modeling of asteroids. Asteroid 1293 Sonja was modeled with purely dense data, and then with a mix of dense and sparse data. The latter approach appears to create a model whose lightcurves resemble the original data more accurately, lending credence to the idea that sparse data can be used to fill in the gaps left by a purely dense lightcurve model. This study shows how the powerful inversion process can be even further refined, creating accurate models that could be used for asteroid mining and collision prevention. [Preview Abstract] |
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G1.00003: The coincident coherence of extreme Doppler velocity events with P-mode patches in the solar photosphere. Rachel McClure, Mark Rast, Valentin Pillet Observations of the solar photosphere show many spatially compact Doppler velocity events with short life spans and extreme values. The striking flashes in the intergranule lanes and the complementary outstanding values in the centers of granules are evident in the spectropolarimetric inversions of SUNRISE IMaX data from the first flight of the SUNRISE balloons in 2009. Using the Fast Fourier Transform, I produce the power spectrum of the spatial wave frequencies and their corresponding frequency in time to create a k-omega diagram which allows distinction of the P-Modes from the granulation. Subsequently, I set a filter velocity and separate the P-Modes from the granulation in each image and test for correlation between the P-Mode Doppler velocities and the granulation velocities at previously identified events. This shows a significant statistical shift in number of events demonstrating some crucial correlation between the granules and the P-Modes. [Preview Abstract] |
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G1.00004: Studying the Polarization of Astrophysical Bow Shocks Austin A. Lin, Manisha Shrestha, Tristan Wolfe, Robert E. Stencel, Jennifer L. Hoffman When a star with stellar wind moves through the interstellar medium (ISM) at a relative supersonic velocity, an arch like structure known as a stellar wind bow shock is formed. These structures can further our understanding of evolved stars and the ISM through observational and computational study. Observations of these structures have been performed for some time, but the recent discovery of many bow shock structures have opened more ways to study them. These stellar wind bow shocks display an aspherical structure, which can polarize the light scattering through the dense shock material. We selected HD 230561 for observation using a catalog compiled from previous studies and observed it in polarized light using the Denver University Small Telescope Polarimeter (DUSTPol). Along with observation, we have simulated the polarization behavior using the Monte Carlo radiative transfer code SLIP. We will present the data from our observations and comparisons between the observational data and the simulation. [Preview Abstract] |
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G1.00005: Comparison of Neutral Planetary Atmospheres with Space Weather Events Bo Johnson, Jan Sojka The purpose of this study was to understand the effects of space weather events on neutral planetary atmospheres. We began with neutral species profiles for Venus through Saturn (involving the three or four most abundant species). We assumed that incoming sunlight was from a blackbody and is the heat source for the atmospheres. Our analysis focused on solar noon, while assuming upper atmospheres were in hydrostatic equilibrium and the neutral temperature at given altitudes was approximately constant. The solar irradiance in the extreme ultraviolet (EUV) and x-ray spectra were assumed to create the dayside ionosphere of the planets by ionizing the atmospheres. After gathering the absorption and ionization cross sections of the atmospheric species in the EUV and x-ray wavelengths, we computed the photon absorption rate from the tops of the atmospheres and the local photon energy deposition rates. In all our planetary atmospheres, the lower atmosphere is protected from space weather solar flares by upper atmospheric absorption of the x-ray photons. This barrier is at a well-defined altitude region called the Sun-atmosphere-interaction-region (SAIR). The local neutral thermal energy content was also calculated. These results were compared with conditions occurring during a hypothetical space weather solar flare event in which the smallest x-ray wavelengths used were increased by a factor of 1000. Future study will develop an understanding of ionization in creating E-regions in planetary ionospheres. [Preview Abstract] |
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G1.00006: VLF monitoring of the ionospheric D-region during the August 2017 solar eclipse Jonh Carlos Mojica Decena, Jan Sojka, Donald Rice The use of VLF signals to monitor the changes that occur in the ionosphere resulting from solar variability, has helped to understand how different ionospheric layers depend upon the Sun. These different ionospheric layers responses play a significant role in determine space weather impacts, and the total solar eclipse of August 21st, 2017 provided a unique opportunity to observe the D-region ionospheric impact on the low altitude waveguide. Our experiment involved monitoring VLF transmissions from the NML 25 KHz in La Moure, North Dakota with receivers located at both Utah State University, Logan, Utah as well as at Riverton, Utah. The path of the eclipse, especially that of totality, passes over the central section of the VLF waveguide of our experiment. We monitored several ``undisturbed'' days to obtain a calibration baseline for the VLF signal. We observed the total eclipse impact on the VLF strength relative to this baseline Our two receiver stations observed a well-defined signal reduction where maximum effect appeared at the time of totality. Also, a small X-ray flare during the eclipse was observed. We will present the detailed description of our experiment set up and the D-regions response to the solar eclipse as observed in the VLF signal strength. [Preview Abstract] |
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G1.00007: Constraining Mantle Discontinuity Structure Beneath North America Andrew Eagon The Earth's mantle consists of discontinuities arising from abrupt changes in mantle mineralogy, a common example of which is a mineral phase change; there are two notable mineral phase changes that occur near the depths of 410 km ($\alpha $-olivine to $\beta $-spinel) and 660 km ($\gamma $-spinel to perovskite$+$magnesiowustite). The variable depth of these discontinuities is tied to thermal properties of the mantle as well as compositional variations. Therefore, it is possible to use depths of observed discontinuities to infer temperature using the Clapeyron slope of the phase change. Thanks to EarthScope's continent-wide coverage, it is feasible to use array methods, such as vespagrams, to detect specific seismic phases that have interacted with discontinuities. The ScS reverberative family -- a group of S waves reverberating between the surface and the core-mantle boundary and interacting with mantle discontinuities along the way -- offers some of the strongest constraints on Earth's deep interior. In this study, we analyze ScS reverberations from events located near or within the continental US and recorded by EarthScope arrays, to calculate the depths of upper and mid-mantle discontinuities. We discuss the depths of the discontinuities in the context of temperature variations and their relationship to other constraints on the structure of the sub-continental mantle beneath North America. [Preview Abstract] |
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G1.00008: Investigating Characteristics of Mesospheric Gravity Waves Over Antarctica Vanessa Chambers, Michael Taylor, Yucheng Zhao, P.D. Pautet As part of the international ANtarctic Gravity Wave Instrument Network (ANGWIN) program, the Utah State University all sky IR imager has been operated at the British Antarctic Survey (BAS) Halley Station (75\textdegree 36$\prime $ S,~26\textdegree 12$\prime $ W) since 2012, obtaining valuable gravity wave information in the higher mesosphere and lower thermosphere region (MLT). In this study, we have utilized a new 3D spectral analysis technique (Matsuda, et al., 2014) to quantify the horizontal phase velocity distributions of gravity waves over Antarctica. This new tool enables us to analyze extensive amounts of airglow imaging data in a relatively short time frame. Additionally, it eliminates the bias present in analyses performed by individuals with varying wave event identification experience. Using this new method, forty nights (total \textasciitilde 500 hours) throughout the 2012 winter season have been analyzed. This study will provide insight into variabilities of the gravity wave energy and propagation characteristics during the 2012 winter season. [Preview Abstract] |
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G1.00009: Phase-shifting Digital Holography for Measuring the Complete Phase Structure of Twisted Light Andrew Voitiv, William Holtzmann, Jasmine Knudsen, Samuel Alperin, Mark Siemens Light that has orbital angular momentum (OAM) is characterized by a helical phase front, which can be thought of as twisting around the axis of propagation. Allen et al showed that these twisted light beams carry an OAM of l$\hbar$ per photon, where l represents the helical mode as an integer. Light with OAM can be fully characterized by measuring its helical phase and amplitude. By utilizing a co-propagating reference beam and applying phase-shifting digital holography, we can measure the complete phase structure and amplitude of a vortex beam, with the advantages of high resolution, high fidelity, and low cost. In addition, these measurements allow for an effortless full modal decomposition. This is a direct and easily-accessible technique for the characterization of OAM. [Preview Abstract] |
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G1.00010: Measuring Quantum Uncertainties using IBM's 5-qubit Quantum Computer AJ Rasmusson, Jean-Francois Van Huele From the original Heisenberg uncertainty relation to modern error-disturbance relations, quantum uncertainty relations describe the limitations of joint quantum measurements. Currently, the relations' range of validity is under experimental test. In May, 2016, IBM launched the IBM Q Experience---a free, programmable web interface directly connected to a 5-qubit quantum computer. I verify specific spin uncertainty relations using the quantum nature of the device. Overall, the 5-qubit device can show no violation of Heisenberg uncertainty and error-disturbance relations. However, violation can occur due to various sources of error and a low number of samples per experiment. [Preview Abstract] |
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G1.00011: Exploring the Challenges of Long-distance Entanglement Distribution Matthew Lawyer, Benjamin Szamosfalvi, Jean-Francois Van Huele Quantum networks promise totally secure communications, but are limited to distances of \textasciitilde 100km. Proposed solutions include a space-based satellite distribution system and a network of quantum repeaters based on entanglement swapping. We review the current status of quantum communication as well as explore the restrictions and challenges that impede the implementation of quantum information tools. [Preview Abstract] |
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G1.00012: F\"{o}rester Resonance Energy Transfer Studies on a Tryptophan-less Green Fluorescent Protein Sean Chi, Tristan Naranjo, Kimberly De La Harpe, Barry Hicks, Latisha Jefferies F\"{o}rester resonance energy transfer (FRET) between tryptophan amino acid residues and a neighboring chromophore has been well studied in green fluorescent proteins. This study investigates the FRET process in a modified green fluorescent protein, pWless, which lacks tryptophan residues, leading instead to FRET between tyrosine and the chromophore. This study compares the photophysical properties of the green fluorescent protein, ecGP123, and the tryptophan-less pWless, and investigates quenching of FRET by TNT derivatives. These findings have the potential to be useful in military, civilian, and private sectors for security and defense against explosive compounds. [Preview Abstract] |
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G1.00013: Radial mode filtering of vortex and vector beams with capillary waveguides David Schmidt, Chloe Keefer, Charles Durfee Vortex and vector beams have been receiving attention in numerous areas of research. Vortex modes are being investigated as channels for carrying information and for their orbital angular momentum properties. Vector beams, with radial or azimuthal polarization, can give pure longitudinal electric or magnetic fields on axis when focused. At the center of the mode, the field goes to zero owing to a singularity in either phase (vortex beams) or polarization (vector beams). These beams are natural modes in free space (Laguerre-Gauss) and circular cross-section waveguides. Optical elements have been developed to produce these beams by applying a spiral phase or polarization rotation to an initial Gaussian beam. The resulting beam has the desired phase or polarization property, but is a superposition of radial modes. In our research, we are interested in mode-specific nonlinear interactions with these beams. In this presentation, we show analytically and experimentally that hollow core waveguides can be used to filter unwanted high-order radial modes of the beam. We describe optimization of the coupling to waveguide and the lossy propagation to predict the ideal filtering properties. We also discuss applications of these beams to third-order mixing and high-order harmonic generation. [Preview Abstract] |
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G1.00014: Progress on developing an MRI analog lensless imaging technique using laser interference patterns. Dionicio Sauer, Jarom Jackson, Dallin Durfee A proof of principle experiment was developed and tested for the development of an MRI inspired lensless imaging technique employing laser interference patterns. One dimensional reflectivity profiles of illuminated samples were generated using the preliminary technique. Principles of the method and the following results will be discussed. [Preview Abstract] |
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G1.00015: Titanium Nitride Nanoparticles as Plasmonic Materials Michael Boergert, Charles Bruce, Michael Granado, Heinz Nakotte In recent years, nanoparticles of Titanium Nitride (TiN) have often been investigated as plasmonic materials for visible and near-infrared wavelengths. In these wavelengths, some TiN nanoparticles have been shown to have optical absorption efficiency to similar-sized particles of silver and gold. One reason for these interesting behaviors in TiN is the stoichiometric mismatch leaving conduction bands open. Using normal valence properties of Titanium and Nitrogen, the formula should be Ti3N4. However, the actual empirical formula is TiN, or depending on preparation conditions, could be TiNX, with X varying from about 0.6 to 1.2. Possible applications due to these unusual properties include sunlight absorbers for more efficient solar power generation, as well as metamaterials and other optoelectronic devices. Our research group investigated the absorption efficiencies for varying size distributions and found that, for certain size distributions, high absorption efficiencies could be achieved. [Preview Abstract] |
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G1.00016: Molecules interacting with intense laser pulses. Andres Mora, Agnieszka Jaron-Becker, Tennesse Joyce, Yuqing Xia Ultrashort high intensity laser pulses have allowed for the observation of ultrafast dynamics in atoms and molecules. Due to the complexity, these multielectron systems interacting with ultrashort intense laser fields are often theoretically studied using the single active electron approximation (SAE). We present here results of simulations within Time Dependent Density Functional Theory which addresses the multielectron nature of the studied systems. Results for ionization of several molecules, High Harmonic Generation (HHG) properties and dynamic localization are discussed. In particular, we show how the resonance effects can modify properties of these processes and how Mollow sidebands can be observed for HHG spectra. [Preview Abstract] |
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G1.00017: Open quantum transport phenomena in nanowires Nathanael C. Smith, Daniel Jaschke, In\'es de Vega, Lincoln D. Carr The analysis of many-body dynamics in open quantum systems has important applications for the development of quantum technologies. In the context of nanoelectronics, we investigate transport through multi-site nanostructures coupled to thermal reservoirs. Using a single channel Lindblad master equation, we simulate the steady state dynamics of local and global observables of these systems via the diagonalization of the Liouville operator. We measure the dependence of transport on the temperatures and chemical potentials of the reservoirs, representing the sites of the structure using established many-body models. For example, we study spin transport along a 5-site nanowire within the ferromagnetic and paramagnetic limits of the quantum Ising model, observing induced current due to biased reservoir chemical potential and transport damping at increased reservoir temperatures. [Preview Abstract] |
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G1.00018: Quantum Dot Localization with Time Resolved Super-Resolution Tracking Microscopy Megan Dunlap, Duncan Ryan, Martin Gelfand, Peter Goodwin, James Werner, Alan Van Orden A novel setup provides simultaneous measurement of the photoluminescence decay time and local position of single emitters with 100 ps time resolution. For the method, a pulsed laser excites a fluorophore positioned in the confocal optical probe region. The subsequent photons are collected with a high numerical aperture microscope objective and imaged onto a 2x2 array of optical fibers in the image plane. Each fiber is connected to one of four single photon counting detectors. To regulate the emitter position, a piezoelectric stage actively adjusts its location with proportional-based feedback from the four detector intensities, so the emitter remains in the center of the probe region. The time-dependent emission observed on the four detectors is used to monitor the spatial position of the emitter with approximately 10 nm precision. This study provides a foundation for later work that will investigate the structural basis of energy transfer among nanoparticles in higher order configurations. [Preview Abstract] |
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G1.00019: Rapid turn-on time for an electromagnet for use in cold atom and ultracold plasma experiments Puchang Jiang, John Guthrie, Jacob Roberts In many experiments with cold atoms or ultracold plasmas, it is desirable to produce magnetic fields using current-carrying coils so that the field can be precisely tuned and can easily be adjusted in magnitude. Production of larger fields often requires several-turn coils given practical considerations, but the resulting inductance of the coils can lead to limitations on how quickly the magnetic field can be changed. We have developed a technique that allows for a rapid turn-on of the current in such a coil using a large external inductor to produce very large emfs to rapidly change the current in the magnetic-field producing coil. We present measurements of our implementation of this technique and discuss its utility in the context of our planned ultracold plasma experiments. [Preview Abstract] |
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G1.00020: An RF 3-D Magneto-Optical Trap for YO Alejandra Collopy, Yewei Wu, Shiqian Ding, Ian Finneran, Loic Anderegg, Benjamin Augenbraun, John Doyle, Jun Ye We implement a laser cycling transition in the molecule yttrium monoxide that allows us to cycle on the order of $10^6$ photons. We utilize this transition to effect slowing from a cryogenic buffer gas cell to trappable velocities. We then load molecules in our 3D RF ($\sim$5 MHz) magneto-optical trap. Looking forward, we plan to utilize a narrower ($\sim$150 kHz) transition to enact further cooling to the 10 $\mu$K regime. [Preview Abstract] |
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G1.00021: Using Spectra and Amplitude to Stabilize an Injection Locked Laser. Ethan Welch, Dallin Durfee, Jarom Jackson An unstable laser can be stabilized by being injection locked by a more stable laser. However, this method is limited because the injection lock only functions when the natural frequencies of both lasers are close together. When the unstable laser drifts too far, it ceases to be stabilized. By analyzing the spectral output of the laser, or by analyzing the overall power output, we can provide active feedback to stabilize the injection lock. [Preview Abstract] |
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G1.00022: Fluctuation Analysis of Evanescent Field Scattering from Nanoparticles Christian Roberts, James Thomas Interactions of nanoparticles and molecules with surfaces is an important application to soft-matter and biological physics. We have developed a variable-angle TIRF illumination microscope for aqueous samples suitable for both scattering and fluorescence fluctuation experiments. The microscope and preliminary results with using gold nanoparticles are presented. [Preview Abstract] |
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G1.00023: Design of Two-Axis Helmholtz Coils Microscope Insert Will Thompson, Meghan Smith, Kathrin Spendier Two pairs of Helmholtz coils were designed to generate an oscillation magnetic field (B-Field) over a volume of 1.0 cm$^{\mathrm{3\thinspace }}$to rotate magnetic particles. The maximum B-field amplitude is approximately 10 mT. The B-field oscillation frequency ranges from 0 -- 1000 Hz. The two coil pairs are designed to fit in Leica's DMI6000 and DMI3000 inverted microscopes. This insert allows us to image rotating magnetic nanoparticles with high spatial and temporal resolution. This poster will show details of the prototype's coil design. The insert was designed in SOLIDWORKS and parts were 3D printed. A manual wire winder was used to wind the magnetic wire on the coils. We are currently testing the performance of this prototype. Our goal is to redesign our current insert to eventually achieve B-field amplitudes of up to 50 mT. We also plan to make the coil design available to other researchers in the future. [Preview Abstract] |
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G1.00024: Imagining of rotating surfactant-coated barium hexaferrite particles in high viscosity fluids Austin Routt, Kathrin Spendier, Meghan Smith, Philippe Jones, Will Thompson Magnetically anisotropic barium hexaferrite (BaFe$_{\mathrm{12}}$O$_{\mathrm{19}})$ nanoparticles were coated through various techniques and with various substances. Primary coatings used were dextran sulfate (DXS), as used on iron oxide, and carboxymethyldextran (CMD). Coatings were done on particles ranging from \textasciitilde 50nm to \textasciitilde 500nm. The coated BaFe$_{\mathrm{12}}$O$_{\mathrm{19}}$ particles were tested for their ability to penetrate high viscosity hydroxyethylcellulose (HEC) gels when subject to an oscillating magnetic field, with and without the influence of a static magnetic field superimposed onto the oscillating field. The oscillating magnetic field amplitudes ranged from 1.0 - 4.0 mT and frequencies ranged from 0 - 100 Hz. The data were analyzed to identify an ideal frequency and field strength for particle penetration time through about 1.0 cm of HEC in a cuvette. Using the frequency and field strength selected, two pairs of Helmholtz coils were designed to fit in an inverted light microscope to image rotating magnetic particles at a high spatial and temporal resolution of 300 nm and 5 ms, respectively. In this presentation, we will show our preliminary data on the imaging of rotating (BaFe$_{\mathrm{12}}$O$_{\mathrm{19}})$ nanoparticles in 1-10{\%} HEC gels and water. [Preview Abstract] |
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G1.00025: All-atom simulations reveal protein charge decoration in the folded and unfolded ensemble is key in thermophilic adaptation Jonathan Huihui, Lucas Sawle, Kingshuk Ghosh Proteins from thermophilic organisms usually melt (unfold from folded) at a much higher temperature compared to their counterparts extracted from mesophilic organisms, despite having very similar structures and sequences. This is a long standing puzzle in protein science with the key question: Is there a general principle that evolution may have used to achieve such high thermal tolerance? However the quest for a general principle has been hampered due to the limits of experimental and computational studies that focus only on a few proteins. We tackle this by studying twelve pairs of homologous proteins from thermophilic and mesophilic pairs using detailed all-atom simulation methods. Our study reveals thermophilic proteins in the folded state have more favorable electrostatics interaction and, contrary to previous studies, we also find more favorable interaction in their unfolded state. This destabilizing effect, however, does not outweigh the favorable effect of the folded state, but highlights the importance of considering the unfolded state. Although electrostatics seems to be primary driving forces behind enhanced stability, we also notice there are secondary strategies (4 out of 12) at play where charge regulation may not be possible for functional reasons. [Preview Abstract] |
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G1.00026: Quantifying randomness of cellular distributions using light sheet microscopy. Warren Colomb, Matthew Osmond, Charles Durfee, Melissa Krebs, Susanta Sarkar The absence of quantitative in vitro cell-extracellular matrix models represents an important bottleneck for basic research and human health. Randomness of cellular distributions provides an opportunity for the development of a quantitative in vitro model. However, quantification of the randomness and deviations from perfectly random cell distributions due to underlying interactions is still lacking. In this paper, we have imaged cellular distributions in an alginate matrix using a multiview light-sheet microscope and quantified the randomness by modeling it as a Poisson process, a process that has constant probability of occurring in space or time. Our light-sheet microscope can image more than 5 mm thick optically clear samples with depth-resolution. We applied our method to image fluorescently labeled human mesenchymal stem cells (hMSCs) embedded in an alginate matrix. Simulated randomness agrees well with the experiments. Quantification of distributions and validation by simulations will enable quantitative study of cell-matrix interactions in tissue models. [Preview Abstract] |
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G1.00027: Size dependence of crowding effect and small molecule crowding Hsuan-Lei Sung, Abhigyan Sengupta, David Nesbitt Cells are exceedingly crowded with 20-40{\%} of the mass taken up by solutes, much different from the dilute buffers where most biological studies are traditionally performed. It's been recognized, for more than a decade, such steric constraint may influence the biomolecule conformations. Previously, macromolecules have been widely used to mimic the crowded environments in cells and shown to greatly promote the biomolecular folding primarily through steric repulsion. Nevertheless, the crowder size dependence has not yet been fully investigated as the role of small molecules in intracellular crowding remains unclear. Cells contain not only macromolecules but also the small solutes like inorganic ions, amino acids and various metabolites. The latter, despite small in individual size, are undoubtedly more abundant and thus they potentially contribute greatly to intracellular crowding. In this work, the crowder size dependence of crowding effect on RNA tertiary structure has been studied by single molecule FRET spectroscopy. The distinct variations in folding/unfolding rate constants along with the predominantly entropic origin revealed in the temperature dependence indicate the crowding effect as major contribution of structure stabilization by both polymer and small molecule crowders. Furthermore, the crowder size dependence is quantitatively described by the physical model where osmotic pressure and excluded volume are considered. Our study provides both experimental and theoretical evidence for small molecule crowding and suggests even stronger crowding effect for small molecule at constant concentration. [Preview Abstract] |
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G1.00028: Visualizing the cytoskeleton architechture of mammalian sperm flagella Terrance Bishop, Xinran Xu, Maria Gervasi, Diego Krapf, Pablo Visconti The mammalian sperm is composed of a head that stores the DNA and a flagellum that propels the cell and which is composed of three compartments: midpiece, principal piece, and end piece. Radially, a central axoneme is surrounded by the outer dense fibers (ODFs). In the midpiece the ODFs are wrapped by a mitochondrial sheath where mitochondria are localized in a unique helical structure, critical for sperm function. As in other cell types, the organization of the cell and its mechanical properties is likely dictated by the cytoskeleton architecture. However, the structure of the sperm cytoskeleton remains unknown. In order to~investigate the actin cytoskeleton in the sperm flagellum, we have employed super-resolution imaging in three dimensions and atomic force microscopy (AFM). We succeeded in visualizing the structure of actin and actin-binding proteins in the sperm tail. Additionally, utilization of AFM assists to resolve the surface topology of the tail. We found that the mid-piece of murine sperm develops a cytoskeleton with a sinistral double-helix pattern. Also, actin-associated proteins spectrin and adducin are also found in these structures. Our findings illustrate a novel structure of actin filaments in a mammalian cell. [Preview Abstract] |
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G1.00029: Magnetic Field between a Pair of Solenoid: Experiments vs. Theory Philippe Jones, Kathrin Spendier, Austin Routt, Will Thompson These experiments compare experimental and theoretical values of the strength of an oscillating magnetic field (B-field) on axis in between two solenoids. The solenoids are made of 24 gauge copper wire, contain different numbers of layers of wire each containing 98 winds that are placed at different (d) apart. The radius of the first layer is 8.55mm. These experiments are important for designing a pair of solenoids that can produce an oscillating magnetic field strong enough for application of magnetic nanoparticle rotation in a highly viscous fluid. A 1-D model was made by using the Biot-Savart Law. The number of layers of wire and winds per layer were taken into account along with the radius of each loop. Measurements of the B-field were taken at d/2 for 1, 5, 9, and 12 layers of 98 winds per layer. The distance between coils was changed from 10mm to 90mm. The measured B-field ranged from 2.00\textpm 5mT to 25.74\textpm 0.05mT depending on the number of layers and distance apart. The results show that experimental B-field values are lower by factors of 1.1 to 1.6 compared to the model for increasing distances. The observed difference is likely due to the limited control and precision of the coil winder used to wind the coils. [Preview Abstract] |
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G1.00030: Nucleus dynamics in budding yeast Carsten Dietvorst, Grzegorz Sikora, Steven Markus, Diego Krapf Timely nuclear movements are essential during many cellular processes such as during brain development in animals, and for proper chromosome inheritance during growth and development of various fungal species. A complete understanding of the process of nuclear migration requires an understanding of the physical properties of the nucleus and the cytoplasm. The budding yeast \textit{Saccharomyces cerevisiae} makes an ideal platform for research due to their genetic tractability, and ease of imaging. We have imaged the nuclei of yeast cells using confocal microscopy, and analyzed the nuclear motion. Our data show that the nuclei experience periods of subdiffusive confinement with occasional periods of superdiffusive directed motion that are attributed to the effect of molecular motors. Future studies will permit us to develop a quantitative description of the viscous and elastic components of the nucleus and cytoplasm that are responsible for the subdiffusive confinement and the properties of external forces required to induce superdiffusive movement. [Preview Abstract] |
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G1.00031: Inferring Details of a Genetic Toggle Switch Network Using Maximum Caliber Stephen Wedekind, Taylor Firman, Kingshuk Ghosh Genetic networks are difficult to characterize, since typical experiments monitor only a few proteins, much less than the actual number of actors involved in the process of gene expression. We aim to learn about the details of the underlying network and the intermediate/hidden species by utilizing crucial information encoded in the stochastic protein expression trajectories recorded over long time. We will exploit this idea using the detailed noise statistics in both protein species of a genetic toggle switch network to successfully infer relevant details of the underlying network -- even when unaware of mRNA levels -- using the principle of Maximum Caliber (the equivalent of Maximum Entropy for dynamics). Using only the simple constraints of protein production, degradation, and mutual repression, the minimal model can reproduce the qualitative features of a switch, as well as quantitative estimates such as protein number and dwell time distributions and reaction rate parameters. [Preview Abstract] |
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G1.00032: Ab Initio Study of Electronic and Magnetic Properties of Co-doped AlAs. Viviana Dovale-Farelo, William Lopez-Perez, Alvaro Gonzalez-Garcia, Rafael Gonzalez-Hernandez First principles calculations were performed to study the electronic and magnetic properties of cobalt doped AlAs within Density Functional Theory formalism. The study was done using a 6.25{\%} Co concentration with a 2\texttimes 2\texttimes 2 supercell. Substitutions of Al or As by Co atoms were done, preferring to replace Al atoms. Total energy calculations for non-magnetic (NM), ferromagnetic (FM) and antiferromagnetic (AFM) states were performed. In the supercell two Al atoms were replaced by two Co atoms at different distances (4.051 {\AA}, 5.729 {\AA}, 7.016 {\AA}, 8.102 {\AA} and 9.922 {\AA}) for five different possible configurations: C0-1, C0-2, C0-3, C0-4 and C0-5. C0-n indicates the configuration corresponding to one Co atom placed in the origin and another one placed in n position. For 6.25{\%} Co-doped AlAs, configuration C0-1 results to be more stable in a FM state with a total magnetization of 4 $\mu $B. In this configuration, the impurities are separated by a distance of 3.960 {\AA}, and the smallest distance between Co-As was of 2.356 {\AA}. The dilute magnetic semiconductor prefers the FM state over the AFM by an energy difference of 25 meV. [Preview Abstract] |
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G1.00033: Hybrid Neutrosophic Triplet Ring in Physical Structures Florentin Smarandache \textbf{~}The Hybrid Neutrosophic Triplet Ring (\textit{HNTR}) is a set M endowed with two binary laws (M, *, {\#}), such that: a) (M, *) is a commutative neutrosophic triplet group; which means that: - $M $is a set of neutrosophic triplets with respect to the law * (i.e. if $x $belongs to $M$, then \textit{neut(x) }and \textit{anti(x)}, defined with respect to the law *, also belong to $M)$; - the law * is well-defined, associative, and commutative on $M $(as in the classical sense); b) (M, {\#}) is a neutrosophic triplet set with respect to the law {\#} (i.e. if $x $belongs to $M$, then \textit{neut(x) }and \textit{anti(x)}, defined with respect to the law {\#}, also belong to $M)$; - the law {\#} is well-defined and non-associative on $M $(as in the classical sense); c) the law {\#} is distributive with respect to the law * (as in the classical sense). [Preview Abstract] |
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G1.00034: Characterizing quantum properties of coupled harmonic oscillators with Husimi visualization Tyler Thompson, Jean-Francois VanHuele ~We examine the dynamics of systems of coupled quantum harmonic oscillators using Lie algebra techniques. The features of the system are then visualized using a time-dependent Husimi function. From these visualizations, we can classify the effects of different couplings and initial conditions on the dynamics of the system to facilitate quantum control. [Preview Abstract] |
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G1.00035: Investigating Causes of The Optical Rogue Wave John Keeney We are investigating two possible causes of the optical rogue wave, the correlation of the refractive index of the propagation medium, and the wavelength of light propagating though that medium. We have determined that there is a direct relationship between the correlation of the medium and the probability of a rogue wave occurring, and an inverse relationship between the wavelength of the propagating light and the probability of a rogue wave occurring. [Preview Abstract] |
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G1.00036: Nontrivial Topological Surface States in SmB$_{\mathrm{6}}$ Thin Films Tao Liu, Yufan Li, Lei Gu, Junjia Ding, Houchen Chang, P. A. Praveen Janantha, Boris Kalinikos, Valentyn Novosad, Axel Hoffmann, Ruqian Wu, Chia-Ling Chien, Mingzhong Wu Being identified as the first rare earth mixed valence system and the first Kondo insulator, SmB$_{\mathrm{6}}$ may very likely be the first topological Kondo insulator as well. Recent studies, theoretical and experimental, have suggested the existence of metallic surface states in single-crystal SmB$_{\mathrm{6}}$ bulk materials, but the presumed topologically nontrivial nature and spatial scale of the surface states, as well as many other aspects, remain outstanding. This work demonstrates the nontrivial topological nature of the surface states in SmB$_{\mathrm{6}}$ thin films via a spin pumping technique with samples of SmB$_{\mathrm{6}}$ thin films grown on Y$_{\mathrm{3}}$Fe$_{\mathrm{5}}$O$_{\mathrm{12}}$ (YIG) slabs. In samples where the SmB$_{\mathrm{6}}$ film thickness ($d)$ is 80 nm or larger, the spin-pumping voltage signal becomes much stronger as the temperature ($T)$ decreases from 150 K to 10 K. Such an enhancement originates from spin-momentum locking of the metallic surface states, thereby providing strong evidence for the nontrivial topological nature of the surface states. The results also suggest a thickness of about 32 nm for the topological surface state, which was confirmed by $T$-dependent transport measurements and theoretical analysis using the tight binding model. [Preview Abstract] |
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G1.00037: Parallel pumping of a ferromagetic nanostripe: confinement quantization and off-resonance driving Patrick Yarbrough, Karen Livesey The parametric excitation of spin waves in a rectangular, ferromagnetic nanowire in the parallel pump configuration and with applied field along the long axis of the wire is studied theoretically, using a semi-classical and semi-analytic Hamiltonian approach. We find that as a function of static applied field strength, there are jumps in the pump power needed to excite thermal spin waves. At these jumps, there is the possibility to non-resonantly excite spin waves near $k_z=0$. Spin waves with negative or positive group velocity and with different standing wave structure across the wire width can be excited by tuning the applied field. By using a magnetostatic Green's function that depends on both the nanowire's width and thickness -- rather than just its aspect ratio -- we also find that the threshold field strength varies considerably for nanowires with the same aspect ratio but of different sizes, in contrast to previous work. [Preview Abstract] |
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G1.00038: Optical Properties of Vanadium Dioxide Films Dana Rampini, Logan Suttin, Joshua Lauzier, Jose de la Venta The temperature dependence of reflectivity, transmission, and absorption of vanadium dioxide films were studied. Vanadium dioxide (VO$_{\mathrm{2}}$ ) undergoes a temperature induced metal to insulator transition (MIT) at 340K, from a monoclinic insulator to a rutile metal. In this work, different thicknesses of vanadium dioxide deposited on Au and Al$_{\mathrm{2}}$ O$_{\mathrm{3}}$ substrates were studied; the optical properties of the films were measured at three different wavelengths in the visible to near-infrared range. The thickness of the vanadium dioxide layer and type of substrate used were the main parameters shown to tune the behavior of the optical properties and the change across the phase transition. For certain wavelengths, the change in measured intensity through the VO$_{\mathrm{2}}$ transition is reversed. These findings suggest that the optical properties of vanadium dioxide films can be tuned with substrate choice and the thickness of the film. [Preview Abstract] |
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G1.00039: Magnetic Domain Morphology in multi-layered [4 {\AA} Co/ 7 {\AA} Pt] thin film Jeremy Metzner A [Co (4 {\AA}) /Pt(7 {\AA})]$_{\mathrm{50}}$ thin film was studied to determine the morphological behavior of the magnetic domains as a function of the magnetic history. This thin film exhibits perpendicular magnetic anisotropy allowing for magnetic imaging using an MFM. A remanent study was performed to find the maximum domain density by analyzing the number of domains as a function of the previously applied magnetic field. These results were compared to those of a descending magnitude magnetic series. From these results a study was performed to determine if the domain density could be further increased. This was done by reapplying the optimal field to enhance the maximum domain density. An in-situ magnetic field was also used to determine the evolution of the magnetic morphology along a few magnetic loops that were applied. Domain periodicity was studied taking a 2-D Fourier transform of the domains pattern. Domain period was determined as a function of the previously applied field. The results of this study were compiled to give a comprehensive understanding of this thin film. Domain density was compared to that of an ascending magnitude magnetic series to determine a biased behavior given by the direction of the applied magnetic series. [Preview Abstract] |
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G1.00040: J-V Distortion in MZO/CdTe Solar Cells Ramesh Pandey, Andrew Moore, James Sites In recent times, sputtered Mg$_{x}$Zn$_{1−x}$O (MZO) has emerged as a better alternative emitter layer for CdTe thin film solar cells(TFSC).The wider band gap and higher transmission of blue photons in MZO helps to mitigate absorption losses typical of traditional CdS buffer layer. Distortion in J−V curve has been observed in CdTe devices with MZO as emitter at various illumination conditions. Previously such distortions have been reported in Zn(S,O)/CuInGaSe$_{2}$, CdS/CuInSe$_{2}$ and CdS/CuIn(SSe)$_{2}$ devices. These distortions are primarily attributed to the presence of secondary barrier formed at the interface between the absorber and emitter layer. The photo-conductivity of the emitter layer at various illumination conditions modifies the barrier due to change in the trap occupancy in the emitter/absorber interface giving rise to such J-V charactersitics. in this work, we have tried to quantify the reason for such distortion in MZO/CdTe devices along with the impact of Cu doping and migration of Cu related impurities in CdTe by putting devices under various stress conditions. The results suggest that the J-V distortion is related to the movement of Cu related trap states in the region of cdTe/MZO interface. [Preview Abstract] |
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G1.00041: The effect of interfacial DMI on the amplitudes of dynamic modes in patterned structures Brayden Johnson, Christopher Ard, Kristen Buchanan Recent work has shown that Dzyaloshinskii Moriya interactions (DMIs) can have a significant effect on spin wave dynamics in extended thin films. Since the effects of DMIs on dynamics are most pronounced for spin waves with short wavelengths, they should be an important consideration for patterned magnetic structures with nanoscale dimensions. Here, we have studied the effect of DMI on the time evolution of the first three dynamic modes in nanoscale circular disks using micromagnetic simulations. We performed cell-by-cell Fourier transforms on the simulation output files to extract resonant frequencies and build mode profiles. The constructed mode profiles show spatial differences with increasing DMIs. In the absence of DMI, the mode is a standing spin wave excitation with a maximum amplitude approximately midway between the vortex core and the disk edge, whereas when DMIs are included, the modes propagate out from the center for a counterclockwise vortex, and involve a larger amplitude near the core and at the edges of the disk. For the higher order modes, the amplitudes of these modes generally increase with increasing DMIs. Modes with even quantization are excited when the DMIs are present. These results show that DMIs can lead to unusual effects in confined geometries. [Preview Abstract] |
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G1.00042: Analysis of Diffusion of a Rhodium Adatom on a Tungsten (111) Surface Dilys Ruan, Eric Putney, Ben Cochran, Matt Koppa, David Dunlap, Paul Schwoebel Information about the transition rate R governing the movement of an adatom between interstitial sites can be determined by examining field-emission microscope images showing the location of the atom at successive times. Once deposited, an adatom won't stay on a surface for long; it might be stripped off under high fields, or it might migrate out of viewing range, so the data is often limited to a few snapshots. In this case, we examine 6 images taken at 10 second intervals showing the location of a rhodium adatom on a tungsten (111) lattice plane consisting of several hundred tungsten atoms. Assuming reflecting boundary conditions at the step edge, we calculate the likelihood distribution of R, and determine the most probable value along with the uncertainty (full-width at half-max). We compare this outcome to the case where the boundary is absorbing, and quantify the differences. Two different computational methods are employed: (i) a direct time-integration of the master equation using 4$^{\mathrm{th}}$ order Runge Kutta, and (ii) a fast diagrammatic method in which the computer is used to enumerate all possible paths. [Preview Abstract] |
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G1.00043: Measuring the Interfacial Dzyaloshinskii-Moriya Interaction in Layered GdCo Samples Katherine Nygren, Robert Streubel, Kristen Buchanan In this poster I will discuss our plans to measure the spin wave frequencies in magnetic GdCo samples capped with platinum (Pt) using Brillouin light scattering (BLS). As a result of the large spin-orbit interactions due to the platinum, these thin films are expected to possess a large interfacial Dzyaloshinskii-Moriya interaction (DMI), which in turn, results in a frequency shift between surface spin waves that propagate in opposing directions. I will discuss how this frequency shift comes about and how it can be detected by BLS as a small difference in the photon frequency from that of the probe laser. We can select different wave vectors k for our spin waves by changing the angle of our sample with respect to the BLS probe laser. Measurements of the surface wave frequencies as a function of k, currently ongoing in our lab, will allow us to obtain a quantitative measurement of the interfacial DMI for these samples. [Preview Abstract] |
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G1.00044: An EAM Model Comparison of the Alkali Metals in BCC, FCC, and HCP Lattice Structures Jake Christensen, Marcus Jackman, Mark Riffe The alkali metals (Li, Na, K, Rb, and Cs) form in body-centered cubic (BCC) lattice structure at room temperature. As temperature is lowered, both sodium and lithium undergo a phase transition to a close-packed structure. Previously, we have developed an Embedded-Atom-Method (EAM) model that accurately describes the vibrational properties of the alkali metals in the BCC structure. Here, we use the same model to calculate the vibrational properties of alkalis arranged in the close-packed face-centered cubic (FCC) and hexagonal close-packed (HCP) lattice structures. The goal is to see if the model can account for the fact that, at higher temperatures, BCC is the preferred structure. This will be done by comparing the free energies of the metals in the three different structures. [Preview Abstract] |
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G1.00045: Template-based electrodeposition of niobium nanowires Kirsten Blagg, Tamara Greymountian, Wolfgang Kern, Meenakshi Singh One dimensional superconducting nanowires have been studied widely for their unique properties and potential applications. In particular, the high critical temperature, high critical magnetic field, resistance to oxidation, and high stability of niobium makes it popular in both arenas. Niobium nanowires have been fabricated through the use of sputtering, molecular beam epitaxy (MBE), lithography and etching techniques. However, these methods are difficult to control, limit nanowire manipulation, and require costly equipment. In this work, we develop a technique for template-based electrodeposition of superconducting niobium nanowires as a simple low cost method to fabricate free standing nanowires. Optimal growth conditions for nanowires are determined using cyclic voltometery. X-ray diffraction and scanning electron microscopy are used to structurally characterize the nanowires. Low temperature resistivity measurements are made in template to determine the superconducting properties of the nanowires. [Preview Abstract] |
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G1.00046: Implementation of the two time-constant model for extracting heat capacity Muadh AL Nadabi, Kate A. Ross Heat capacity is the heat required to change the temperature of a material. The heat capacity of solids can provide substantial information about the lattice and magnetic properties of materials. As part of their commercially available Physical Properties Measurement System (PPMS), Quantum Design Inc. created a program that measures thermal relaxation curves and extracts the heat capacity via a “two-time constant” model. This model consists of two coupled differential equations that describe the temperature of the sample and the temperature of the measurement platform as a function of time. However, the commercial program does not provide the ability to re-fit the raw data with restricted variable ranges to improve the fits, and we have observed poor fits for some curves. We are creating a program using the two-time constant model that will allow the user more control over the fitting of the raw thermal relaxation data. We will present the model and outline our approach. [Preview Abstract] |
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G1.00047: Exploring the Effects of Interfacial Dzyaloshinskii-Moriya Interactions on Patterned Nanomagnets Christopher Ard, Brayden Johnson, Kristen Buchanan The Dzyaloshinskii-Moriya interactions (DMIs) that lead to the stabilization of skyrmion spin textures also have a strong effect on dynamic excitations in magnetic materials. Recent work has shown that when one includes the DMI energy term, spin waves propagating in opposite directions along an extended thin film will have different frequencies. Here we have explored the effects of the DMIs on spin wave excitations in nanoscale magnetic disks and rings using micromagnetic simulations and we find that the effects are considerable. We chose a magnetic vortex state for this study since the vortex radial modes should be maximally affected by the introduction of DMIs. Simulations were conducted for nano-sized disks with realistic DMI values for ferromagnetic/heavy metal layers. The results show that the mode frequencies are quantized with or without the DMIs as expected for a nanoscale disk, but when we introduce DMIs we find that not only are the mode frequencies shifted, the modes patterns are also affected. The modes now propagate radially inward or outward depending on the vortex chirality. The mode frequencies generally increase with increasing DMIs and increase as a function of 1/radius. [Preview Abstract] |
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G1.00048: Searching for Indirect Optical Transitions in Semicon- ductor Quantum Ring Nanostructures using Light with Orbital Angular Momentum Andrew Johnson, Mark Siemens, Guillermo Quinteiro, Stefano Sanguinetti, Sergio Bietti We present the results of micro-photoluminescence ($\mu$-PL) experiments on GaAs quantum ring nanostructures (QR) when pumping with light having Orbital Angular Momentum (OAM). Excitons in QRs excited by twisted light (TL) have been predicted to absorb the OAM from the light, resulting in "indirect" optical transitions. Photoluminescence from several $(\sim20)$ QRs is collected using a $\mu$-PL apparatus. Preliminary results when pumping with $\ell=1$ showed no noticeable change in the PL spectrum, though the significant number of QRs imaged onto the spectrometer likely obscured any change in the spectrum resulting from OAM-transfer. [Preview Abstract] |
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G1.00049: Optical Floating Zone Growth of Yb$_2$Si$_2$O$_7$ Antony Sikorski, Harikrisnan S. Nair, Kate A. Ross We report the successful growth of single crystals of Ytterbium Silicate (Yb$_2$Si$_2$O$_7$) using the Optical Floating Zone (OFZ) technique. This compound is a strongly spin orbit coupled Quantum Dimer Magnet, as evidenced by the temperature dependence of its magnetic heat capacity, and may exhibit novel magnetic field induced phases of matter. Large single crystals of Yb$_2$Si$_2$O$_7$ are needed in order to study its anisotropic properties via neutron scattering. Typical OFZ-grown crystals of Yb$_2$Si$_2$O$_7$ are 0.5 cm x 0.5 cm x 0.3 cm pieces which break off from the as-grown boule. The tendency to form a multi-domain boule suggests an unreported structural transition near the melting temperature, which is consistent with other members of the rare earth $R_2$Si$_2$O$_7$ series. [Preview Abstract] |
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G1.00050: Coherent Data Acquisition Expedited by Collection in Arbitrary Time Directions Geoffrey Diederich, Mark Siemens MultiDimensional Coherent Optical Photocurrent Spectroscopy ($MDCOPS$) is an experiment that allows for the acquisition of one-dimensional spectra in any arbitrary time direction in the $t$-$\tau$ plane. According to the Projection Slice Theorem of Fourier Transforms, a projection of a MultiDimensional Coherent Spectroscopy ($MDCS$) spectrum onto any arbitrary axis in the $\omega_t$-$\omega_{\tau}$ plane can be acquired by simply taking a one-dimensional spectrum of the four-wave mixing signal while moving both the $t$ and $\tau$ stages concurrently. Conventional $MDCS$ experiments are limited, by their signal detection, to collecting an entire spectrum and taking slices of the resulting data to look at resonance lineshapes. Using the $MDCOPS$ experiment, with smart choice of the direction of data collection, allows direct observation of material properties such as the homogeneous and inhomogeneous linewidths of a resonance, off-diagonal coherence peaks, and population decay peaks with far fewer data points necessary than an entire $MDCS$ spectrum. [Preview Abstract] |
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G1.00051: FMR at High Temperature Sidney Katz, Daniel Richardson, Mingzhong Wu We take Ferromagnetic Resonance (FMR) Measurements and study thin films. I work with the high temperature system studying the effects of HAMR media samples at high temperature. The HAMR media sample we are testing is iron platinum. The iron platinum is on glass substrate and is only 10nm thick. Some of the samples will have a soft magnetic layer deposited on top of FePt layer, which is around 2-4nm thick. The soft layers deposited on the FePt are iron cobalt alloys. To know the data is accurate with the high temperature system we test it with Yttrium Iron Garnet (YIG). YIG has very low damping, thus power absorption is higher. Also, the properties of YIG have been studied before at high temperature many times before. The purpose of this research is data storage. The closer these grains get to each other the data storage increases and the more likely the exchange field from one of the grains will flip the other. The purpose of this study is to know the damping of the grain at high temperature, so hardware developers know how the damping changes with temperature so that the optimum temperature for hard drive performance can be selected. [Preview Abstract] |
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G1.00052: Luttinger-Tisza method applied to frustrated magnetic systems Ethan Coldren, Martin Gelfand, Kate Ross A frustrated magnetic system is one in which a spin `wants' to align with some of its neighbors, but `wants' to anti-align with others, and a long range ordered state that completely satisfies all interactions is not possible. This can lead to many interesting spin structures, including helical phases with incommensurate ordering wavevectors. In order to determine the magnetic structure of a given frustrated Hamiltonian, we developed a program that uses the Luttinger-Tisza method to predict the ground state spin configuration. This is used to compare to neutron scattering data on materials thought to embody the frustrated spin models. The program has been tested for the $J_1-J_2-J_3$ Heisenberg model on a honeycomb lattice, for which the exact results are known. The method was then applied to a $J_1-J_2$ Heisenberg model for the three dimensional lattice appropriate to the higly frustrated material Fe$_3$PO$_7$. The result for the relevant parameter regime for Fe$_3$PO$_7 (\frac{J_2}{J_1}=1.9)$ is a quasi-degenerate ring of $\vec k$-vectors, in excellent agreement with observations from neutron scattering. Our result for Fe$_3$PO$_7$ gives insight as to why this material does not form a fully long range ordered state, but instead forms nanosized domains of partial helical order. [Preview Abstract] |
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G1.00053: Solving the Bogoliubov-de Gennes Hamiltonian for a $p$-wave superconductor on a triangular lattice Aidan Winblad, Hua Chen The Bogoliubov-de Gennes (BdG) Hamiltonian is commonly used for describing quasiparticle excitations in superconductors. We want to solve the BdG equation for a $p_x+ip_y$ superconductor on an equilateral triangle of finite lattice sites. An equilateral is chosen because it is topologically equivalent to a 1-D T-junction, and we want to determine how the physics maps from an equilateral triangle to the T-junction geometry. We diagonalized the lattice version of the BdG Hamiltonian, using a simple python script, to find the energy eigenvalues and the corresponding eigenstates of the system, first for a 1D $p$-wave superconducting wire and then for an equilateral triangle. Alternatively, we also solved the continuum BdG equation analytically in both momentum space and real space with proper boundary conditions for a given geometry. Understanding the mapping from an equilateral triangle to a T-junction would have significance in building practical logic units for topological quantum computation. [Preview Abstract] |
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G1.00054: Polarization Sensitive Coherent Diffraction Imaging for Insect Structures Hannah Rich, Dmitry Karpov, Edwin Fohtung Anisotropy in dielectric and multiferroic materials as well as in optically transparent oxides are being actively pursued by researchers due to their broad potential application as elements in photonics and sensor devices, and as template materials in energy storage and conversion devices. It is therefore vital to be able to probe the structure-property relationship in such materials. We report on an experimental setup to study the optical and functional properties of a bio-inspired multilayer structure. We use the concept of bio-mimetic of an insect wing that serves as a possible template material for photonic applications. We develop an experimental imaging technique that utilizes the interaction of polarized visible light with the insect wing. By mapping the response function of the complex polarized beam with the insect wings, we provide images of the changes of the complex index of refraction as a function of beam polarization. [Preview Abstract] |
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G1.00055: Characterizing Large-Pore Protein Crystals for Advanced Material Applications Luke F. Hartje, Brian E. Munsky, Christopher D. Snow With rapidly growing interest in therapeutic macromolecules, high-density information storage, and advanced biofunctional fabrics comes the need for new materials capable of guest macromolecular storage and metered release on the nanoscale level. One novel possibility for such materials are engineered large-pore protein crystals (LPCs). Composed of numerous chiral constituents, LPCs are ordered biologically derived nanoporous materials exhibiting hexagonal close-packed pores greater than 8 nm. These substantial pores distinguish LPCs from typical nanoporous scaffolds, enabling engineered LPC materials to readily uptake, immobilize, and controllably release macromolecular guests. The chemical diversity and functional versatility of LPCs make them promising targets for use as nanostructured scaffolds with potential applications in drug delivery, biosensing, enantiomer separations, and multifunctional textiles. This work highlights our efforts to experimentally and computationally investigate macromolecular transport and interaction energies within an LPC environment using time-lapse confocal microscopy, bulk equilibrium adsorption, and hindered diffusion simulation. [Preview Abstract] |
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G1.00056: Simulation of Amorphous Silicon Thin Film Transistors William Schenken, Idemudia Airuoyo, Reuben Collins Amorphous and crystalline silicon are some of the most commonly used materials in modern solar cells and microelectronic devices due to silicon's abundance, low cost, and device performance. Thin film transistors (TFTs) using amorphous silicon and related materials represent an important class of silicon-based devices. Accurate modeling and simulation of amorphous silicon TFTs allows for more effective and efficient ways of optimizing adjustable parameters and extracting useful information not easily obtainable through experimentation. Using material parameters previously developed to accurately simulate amorphous silicon solar cells, this study presents finite element analysis of amorphous silicon TFTs and a comparison to experimental results. The simulations are used to guide understanding of the effect of defect structure on device metrics. The intensity dependent photoresponse of the TFTs is also explored to assist in extracting defect structure from experimental results. The use of simulation in interpreting experimental results is found to improve understanding and minimize the time required to optimize devices. [Preview Abstract] |
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G1.00057: Broad-Area Surface Nano-Patterning by Ion Beam Sputtering Emmett Randel, Carmen Menoni, R. Mark Bradley, Matt P. Harrison Self organized nano-patterning by low energy ion beam sputtering (IBS) is a promising technique for producing nanostructures. Uniform structures in a variety of materials can be patterned quickly over large areas. Nano-ripples were produced by sputtering Si (100) substrates with Ar$^+$ ions at near normal incidence during the co-deposition of Ta and Mo impurities. The Ta was introduced using a separate target and source, allowing for control of impurity flux and energy. The Mo was introduced by sputtering an Si substrate surrounded by Mo plate. It is shown that the orientation of ripples can be controlled with the impurity flux. The patterning of ripples and terraces in the absence of impurities was also explored. Si (100) substrates were sputtered at high angles of incidence by Ar$^+$, Kr$^+$, and Xe$^+$ ions. It is shown that short wavelength ripples appear early in the pattern formation, and over time the pattern coarsens, leading to long wavelength structures dominating. This work was performed in tandem with theory in an effort to refine models. [Preview Abstract] |
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G1.00058: Temperature Dependence of Electrostatic Discharge in Highly Disordered Polymers Tyler Kippen, Allen Andersen, JR Dennison The study of electrostatic discharge (ESD) has direct applications to spacecraft charging, along with many high voltage DC power applications, making it critical to understand how ESD varies due to changing environmental conditions, including temperature. Standard step-up to electrostatic discharge tests were performed on several polymers, including low density polyethylene (LDPE), polyetheretherketone (PEEK), and Kapton at temperatures ranging from 260 K to 360 K. Preliminary analysis suggests that temperature affects the breakdown field strength, but that the effects are strongly material dependent. These results are compared to a proposed atomic scale model of how defect sites trap charge carriers, leading to charge build up and eventual breakdown. Our dual-defect theory for ESD incorporates both lower energy recoverable defect modes that can be generated and annihilated through thermal annealing and higher energy irrecoverable defect modes such as those created by radiation damage. The model suggests that at lower electric field strengths, an annealing process occurs due to higher temperatures which limits the density of low energy defects in the material. [Preview Abstract] |
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G1.00059: Resistivity of Nickel Thin Films Michael Maynard, Jameson Curtis, Samuel Tobler As metal films get thinner, their resistivity increases. We study this phenomenon using nickel films. The nickel films are made in a vacuum system with pressures below 10\textasciicircum -7 Torr. A nickel filament is heated to 1200\textdegree C to sublimate the nickel onto our glass substrate. A four-point measuring probe was used to measure voltage drops across the film at known currents. This gave a sheet resistance. Thickness of the thin films was verified by images on a scanning electron microscope. Thicknesses varied from 40 nm -- 255 nm. Resistivity of films were calculated to be between 22 - 147 $\Omega $ nm. A graph of resistivity vs thickness will be presented and discussed on this poster. [Preview Abstract] |
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G1.00060: Electron Yield of a Carbon-composite Nanodielectric Matthew Robertson, JR Dennison, Justin Christensen Electron irradiation experiments were conducted to investigate the electron transport, charging, discharging, and emission properties epoxy/carbon-fiber composite material. We discuss how these results are influenced by the nanoscale structure of the conducting carbon fibers embedded in the dielectric epoxy matrix. Electron yield measurements were made in an ultrahigh vacuum electron emission test chamber, with electron beam energies ranging from 15 eV to 5000 eV. Related structural and charging priorities have also been measured by scanning electron microscopy, energy dispersive x-ray analysis, cathodoluminescence, electron-induced arcing, and conductivity. The emission properties of the composite material are considered, in regard to models which combined the two component base material emission properties. [Preview Abstract] |
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G1.00061: Diamond Detectors for uses in a Proton Therapy Beam Holly Johnson, Anna Zaniewski, Ricardo Alarcon, Jason Holmes, Trevor Van Engelhoven, Robert Nemanich Proton beam therapy is a form of cancer treatment that allows us to target and treat cancerous cells. High-energy protons deposit most of their energy immediately before they come to rest, forming a peak of energy deposition called a “Bragg Peak”. Thus, beams of protons can be tuned to pass through skin and healthy tissue to release their energy inside the tumor, leaving the healthier cells around it unaffected. However, precise knowledge of the beam’s position and energy is required for this targeting. Yet, current detectors, based on silicon, wear down and need to be replaced often, need frequent calibration and are susceptible to noise, having a band gap of 1.14 eV. A diamond’s band gap of 5.45 eV means that it is not susceptible to thermal noise, and its structure is more robust to radiation damage than silicon. In this project we present a diamond-based proton detector. This detector is made with an optical-grade diamond sample cleaned thoroughly with Piranha (70% sulfuric acid and 30% hydrogen peroxide), ozone, and plasma before having metal electrode layers of titanium, platinum, and gold deposited on either side of it using an E-beam evaporator. The sample is then cleaned again with plasma and ozone, and then tested with radioactive sources. [Preview Abstract] |
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G1.00062: Fabrication of Linear Nanostructures Via Laser Interference Lithography Amanda Matheson III-V compounds are desirable semiconductor materials for tandem photovoltaic cells, with many alloys having a direct band gap and appropriate band gap values; however, III-V substrates are much more expensive than silicon to produce, which makes them undesirable for commercial terrestrial solar applications. III-Vs can be grown epitaxially on a v-grooved silicon substrate with (111) planes exposed, which prevents the development of anti-phase domains (APDs). APDs can result in reduced device efficiency and must be avoided. We use laser interference lithography (LIL) capable of patterning linear nanostructures with pitches below 300 nm. LIL is faster and less expensive than conventional methods of patterning at these length scales (such as electron-beam lithography), and can be performed on rough surfaces. We have successfully patterned linear nanostructures with different pitches across a silicon substrate area of 1 cm x 1cm. Future work includes developing LIL and v-groove etch process parameters on silicon typical of that used in commercial photovoltaics. [Preview Abstract] |
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G1.00063: Fabrication of Omniphobic and Superomniphobic Surfaces with Inexpensive Lasers Sanli Movafaghi, Anudeep Pendurthi, Wei Wang, Soran Shadman, Azer Yalin, Arun Kota Super-repellent surfaces can be broadly classified as superhydrophobic surfaces (i.e. surfaces that are extremely repellent to high surface tension liquids like water) and superomniphobic surfaces (i.e. surfaces that are extremely repellent to both high surface tension liquids like water and low surface tension liquid like oils and alcohols). Super-repellent surfaces can be fabricated by combining a surface chemistry that imparts low solid surface energy with an appropriate surface texture. Recently, fabrication of superhydrophobic surfaces via surface texturing with lasers has received significant attention because laser texturing is scalable, solvent-free, and can produce a monolithic texture (i.e. texture which is an integral part of the surface unlike a coating that is deposited on the underlying substrate) on virtually any material. However, to the best of our knowledge, there are no reports of superomniphobic surfaces fabricated via laser texturing. Further, most reports of superhydrophobic surfaces fabricated via laser texturing have employed expensive nanosecond or femtosecond lasers. In this work, we present laser textured superomniphobic surfaces fabricated with an inexpensive CO2 laser engraver. We demonstrate that our simple, inexpensive, scalable and solvent-free laser texturing technique allows fabrication of superomniphobic (or omniphobic) surfaces, gradient wettability surfaces, and droplet manipulation tracks with a wide variety of materials. \newline [Preview Abstract] |
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G1.00064: Fabrication of Super-repellent Films for Effective Chemical Shielding. Hamed Vahabi, Wei Wang, Sanli Movafaghi, Arun Kota Chemical shielding has known as a potential application of superomniphobic coatings due to their capability in repelling virtually all liquids from the solid surfaces. However, fabrication of most superomniphobic surfaces requires complex process conditions or specialized and expensive equipment or skilled personnel. In order to circumvent these issues and make them end-user-friendly, we developed the free-standing, flexible, superomniphobic films. These films can be stored and delivered to the end-users, who can readily attach them to virtually any surface (even irregular shapes) and impart superomniphobicity. The hierarchical structure, the re-entrant texture, and the low solid surface energy render our films superomniphobic for a wide variety of liquids. We demonstrate that our free-standing, flexible superomniphobic films are well-suited for chemical resistance applications because of the excellent chemical stability of the F-SiO2 particles used in fabrication of the films. [http://dx.doi.org/10.1063/1.4989577] [Preview Abstract] |
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G1.00065: A thermal sensitization approach toward the nano/microstructuring of binary alloy surfaces to tune their wettability. Hamed Vahabi, Wei Wang, Ketul Popat, Gibum Kown, Troy Holland, Arun Kota Superhydrophobic surfaces (i.e., surfaces extremely repellent to water) allow water droplets to bead up and easily roll off from the surface. While a few methods have been developed to fabricate metallic superhydrophobic surfaces, these methods typically involve expensive equipment, environmental hazards, or multi-step processes. In this work, we developed a universal, scalable, solvent-free, one-step methodology based on thermal sensitization to create appropriate surface texture and fabricate metallic superhydrophobic surfaces. To demonstrate the feasibility of our methodology and elucidate the underlying mechanism, we fabricated superhydrophobic surfaces using ferritic (430) and austenitic (316) stainless steels (representative alloys) with roll off angles as low as 4\textdegree and 7\textdegree , respectively. We envision that our approach will enable the fabrication of superhydrophobic metal alloys for a wide range of civilian and military applications. [http://dx.doi.org/10.1063/1.4989577] [Preview Abstract] |
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G1.00066: Device Architecture for Next Generation CdTe PV Alexandra Huss, Anna Wojtowicz, Jennifer Drayton, James Sites, Darius Kuciauskas Thin CdTe solar cells with absorber thickness of approximately 1.0 $\mu $m were fabricated with varied close-space sublimation (CSS) conditions to optimize the performance of the cells. A CdCl2 dose time of approximately 125 seconds is the optimal treatment for passivation of these devices, and the addition of an optimal CuCl treatment of 2 second dose time with a 50 second anneal produces a 1.0 $\mu $m cell that is approximately 14{\%} efficient. Single and two-photon TRPL measurements from both sides of the solar cell indicate that back interface recombination dominates recombination losses and a high diode quality factor is the main limitation on fill factor for thin CdTe cells. The optimized device structure produces devices that have repeatable \textasciitilde 14{\%} efficiency and cells show excellent crystal structure and continuous MgZnO and Te layers. [Preview Abstract] |
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G1.00067: Further constraints on the diffuse neutrino background from primordial black holes Dustin Nguyen Black holes are very interesting theoretically because their study brings together big theories and fields in science, namely: general relativity, quantum mechanics, and cosmology. It is theorized that primordial black holes (PBHs) with a wide range of masses could have been formed in the early universe as a result of the great compression associated with the Big Bang. For a PBH population with individual masses $M_*<10^{15}$ g, we expect an explosive burst, through the process of Hawking radiation, which marks the end of their life. We calculate the energy spectra and flux of all three neutrino flavors emitted during the final evaporation of PBHs with mass $M_*$. We investigate bounds that can be deduced from recent gamma-ray measurements and results from kilometer-scale detectors - an improvement on former work that used primarily only data from atmospheric and solar experiments. [Preview Abstract] |
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G1.00068: Python-Based Tool for Universal Nuclear Data Extraction William McDonald, Hayden Blair, Jesssica Berry, Peter Consalvi, Markus Garbiso, Yanina Liktenshteyn, Matthew Martin, Kyle Leach Over the past 70 years, nuclear physics experiments have provided a vast wealth of experimental data on both ground and excited state properties across the nuclear chart. In many cases, searching for and parsing the relevant nuclear structure data from previous work can be tedious and difficult. Although the compilation, evaluation, and digitization of this data by multiple groups around the world over the past several decades has helped dramatically in this respect, the process of performing systematic studies using this data can still be cumbersome and limited. We are in the process of creating a python-based program to extract, sort, and manipulate nuclear and atomic data efficiently. In its current state, the program is able to extract all atomic-shell ionization energies, excited- and ground-state nuclear properties, and all beta-decay rates and ratios. As a part of this ongoing project, we plan to use this tool to examine beta-decay rates in extreme astrophysical environments. [Preview Abstract] |
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G1.00069: Testing of New Chip Design for Atlas Inner Tracker at CERN Michael Kaemingk The ATLAS detector at the LHC will be undergoing its phase II upgrade. As part of this upgrade, a new pixel chip is being developed for the inner tracker part of the detector. The new pixel chip design must be tested to ensure that it copes with all the requirements for the upgraded ATLAS detector, which will include a 10-fold increase in the radiation dose that the pixels will be receiving. The work in conducting these tests includes building different testing set-ups, creating the software to run and monitor these set-ups, and storing and analyzing the data from the tests. [Preview Abstract] |
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G1.00070: Electron Collisions and Ionization of Argon Gas in the Inductively Coupled Plasma Mass Spectrometer Carson Evans, Ross Spencer The plasma torch of the Inductively Coupled Plasma Mass Spectrometer (ICP) is powered by a 3-turn coil attached to a radio-frequency generator running at 40 MHz. The discharge is started by a Tesla coil that briefly ionizes a small fraction of the argon gas flowing through the coil. After the initial ionization pulse, the RF field produces the electric field that gives the electrons enough energy to heat the argon gas. As the electrons gain energy from the RF field they reach an energy capable of either exciting or ionizing the argon atoms. We are modeling the effect of the RF field on the electrons as well as the effect of collisions between electrons with neutral, excited, and ionized argon and with other electrons. We are also including the possibility of de-excitation argon. Our goal is to see an electron avalanche, a chain reaction where electrons ionizing argon neutrals create more free electrons which in turn ionize more argon. [Preview Abstract] |
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G1.00071: Using laser ionization to design a plasma wakefield accelerator that preserves beam emmittance Christopher Doss, Michael Litos, Robert Ariniello Beam-driven plasma wakefield accelerators (PWFA) are a strong candidate for future high energy particle accelerators, particularly for electrons and positron. The PWFA has demonstrated multi-GeV/m acceleration in experiment, though a remaining concern is conserving the emmitance (spread of particles in phase-space) of a beam as traverses the plasma. One solution is to guide the beam into the PWFA using a precisely ionized plasma source generated with a high intensity laser pulse. We present simulations that show ionization of suitable plasma density profiles and plan on implementing these results in laboratory experiment. A tandem lens system propagates a laser pulse into $10^{16}\,\mathrm{cm}^{-3}$ density Argon gas and can ionize a plasma column on the order of 50 cm in length. We also explore implementation of thin plasma lenses to supplement the main plasma source as a secondary strong focusing element. We show generation of a suitable thin plasma lens by using an asymmetric Gaussian laser pulse to ionize a small, dense plasma between two Argon gas jets. [Preview Abstract] |
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G1.00072: VASIMR Fabrication Team at Utah Valley University Eli Atkin, Michael Burt, Mason Acree, Sam Otero, Phil Matheson, Raymond Perkins The Utah Valley University (UVU) Physics Department has formed an undergraduate research team to create a functioning VAriable Specific Impulse Magnetoplasma Rocket (VASIMR). We anticipate the equipment and expertise gained to further plasma physics research at UVU, and to also provide learning platforms in computation, theory and experimental techniques for our undergraduate students. Our plasma generation and containment system is made up of a quartz tube leading from a gas inlet to the expansion chamber. Waveguides will be constructed to focus the microwaves generated by a magnetron to produce an argon plasma in the tube. Four fabricated electromagnets surrounding the quartz tube will provide the VASIMR heating chamber. Our expansion chamber consists of a steel bell jar, obtained from an outside source. Parts have been machined by team members to fit the bell jar to our purposes. Other components include a turbo vacuum pump, roughing pump, gauges, and plexiglass viewport. Initial sensors for this project will include Langmuir probes, interferometers, and pressure monitors, with additional sensors added in the future. [Preview Abstract] |
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G1.00073: SEPh. Xitlally Salmon The Society for Engineering and Physics (SEPh) is a new organization working towards providing a professional society for Engineering Physics, as well as bridging the gap between the two fields both on a local level at NMSU and on a National level . To accomplish this goal, SEPh focuses on student projects, allowing students to design and create projects that show interesting physical principles, such as a Tesla Coil or a Telescope. Additionally, SEPh focuses its efforts on public outreach, using our projects to show Engineering Physics to the community. Through these efforts, we hope to provide a network for Engineering Physics students, faculty and industry partners as well as encourage children to explore Engineering and Physics. [Preview Abstract] |
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G1.00074: Neutrosophic Modal Logic and its Physical Applications Florentin Smarandache \textit{Neutrosophic Modal Logic }is a logic where some neutrosophic modalities have been included. Let P be a neutrosophic proposition. We have the following types of \textit{neutrosophic modalities}: \textit{I. Neutrosophic Alethic Modalities }(related to truth) has three neutrosophic operators: \textit{Neutrosophic Possibility}: It is neutrosophically possible that P. \textit{Neutrosophic Necessity}: It is neutrosophically necessary that P. \textit{Neutrosophic Impossibility}: It is neutrosophically impossible that P. II. \textit{Neutrosophic Temporal Modalities }(related to time) It was the neutrosophic case that P. It will neutrosophically be that P. And similarly: It has always neutrosophically been that P. It will always neutrosophically be that P. III. \textit{Neutrosophic Epistemic Modalities }(related to knowledge): It is neutrosophically known that P. IV. \textit{Neutrosophic Doxastic Modalities }(related to belief): It is neutrosophically believed that P. V. Neutrosophic Deontic Modalities: It is neutrosophically obligatory that P. It is neutrosophically permissible that P p.). [Preview Abstract] |
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G1.00075: What Can we Learn from the Solution to the Quantum Rabi Model? Tyler Kharazi The Rabi model is a fundamental model in the study of quantum optics introduced by Rabi in 1937, which was recently solved analytically (Braak 2011). We review different methods to solve dynamical problems in quantum optics, and we explore how they can be applied to specific quantum optical models. These solution methods leads us to consider symmetries and limiting cases of these models. [Preview Abstract] |
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G1.00076: Expressing fractional derivatives as integer derivative series: physical and numerical applications Anastasia Gladkina, Gavriil Shchedrin, Usama Al Khawaja, Lincoln D. Carr Fractional derivatives, by extending the local definition of integer order derivatives to derivatives of non-integer order, are successful at describing systems with nonlocality, fat-tailed distributions, and multiscale hierarchy. In this work we use the displacement operator to derive an infinite series of integer order derivatives for the Gr\"{u}nwald-Letnikov fractional derivative. By truncating the infinite series and retaining only the first few terms, we find that functions normally characterized by Taylor series with a finite radius of convergence have an infinite radius of convergence in the integer derivative expansion, as is the case for a physically relevant hyperbolic secant function that represents a bright soliton. We show utility of the truncated integer derivative expansion by solving a linear fractional differential equation with constant coefficients by replacing the fractional derivative with integer derivatives up to the second order. This generates only a 1 percent error in the numerical solution. Such a decomposition is useful for the characterization of classical multi-scale materials, such as materials with memory or porous media, and can be further generalized to include quantum materials that are described by the fractional Schr\"{o}dinger equation. [Preview Abstract] |
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G1.00077: Measuring Atmospheric Muon Flux during the 2017 Solar Eclipse Joshua Fender, John Ringler, Justin Morse For this project, we measured atmospheric muon flux as a function of altitude during the 2017 solar eclipse. This was done as a test of a detector we developed. We wanted to see if it could be used to resolve any difference between the flux measured during the eclipse and average conditions. The detector was part of a self-contained autonomous payload that was carried up to altitude aboard a weather balloon. The payload contained three Geiger counters connected to a coincidence circuit, making up the detection system. This system, along with various other sensors including an internal temperature sensor and altimeter, are controlled by an onboard Arduino Mega microcontroller. An internal frame was constructed to protect the payload components using 3D-printed parts. The payload was launched during the 2017 solar eclipse from Guernsey, Wyoming, very close to the path of totality. Initial data analysis suggests that line-of-sight blockage of the sun due to a total eclipse produces little to no difference in muon flux when compared to the results of previous daytime flights. [Preview Abstract] |
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G1.00078: Electroencephalography and the Mechanical Operation of an Exoskeletal Arm Cody Helms, Kourteney Zadina Great advancement in technology has opened the doors for research in the field of prosthetics, specifically prosthetics controlled by the mind. Every action we take within our daily lives requires our brains to produce electrical activity. This activity generates brain waves that can be observed and recorded using electroencephalography (EEG). Utilizing machine learning algorithms trained to determine which brain waves are associated with moving an arm, it is possible to control a pneumatic exoskeletal arm with nothing more than your thoughts. Our research focuses on measuring brain wave activity during particular movements of the body. We attempt to find brain waves corresponding to the movement of raising and lowering the arm by using EEG hardware. We hope this work could, someday, be applied in operating a prosthetic arm that amputees or physically disabled people could use. [Preview Abstract] |
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G1.00079: Postural Control: A Sample Entropy Approach to One-Legged Stance Taylor McMillan We became interested in knowing whether any notable differences could be discerned, during one-legged stance, between an individual's dominant and non-dominant foot via the sample entropy algorithm. Sample Entropy is a method by which one can gauge the complexity of system evolving with time. There were 5 participants for this study, all of whom had a dominant right foot. We used this algorithm to measure the complexity of the force and jerk generated by an individual during unipedal stance. Preliminary results suggest that sample entropy can resolve a difference in the dynamics of each leg while attempting to maintain balance. [Preview Abstract] |
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G1.00080: Biomimicry: Designing and Building a Multilegged Robot Arick Sweitzer I designed and built a robot we call the ``centipede''. As the name suggests, this is a multilegged device that competed in the 2017 Colorado Space Grant Consortium robot challenge in which robots are to make their way to a radio beacon while autonomously navigating an obstacle course designed to thwart their progress. I have built prototype legs (using a 3-D printer and some servo motors) driven by an algorithm which maintains the marching order of the legs and allows for steering control. The algorithm alone presents several interesting challenges such as getting the legs to move in a manner like a wave train and dealing with robot stability during motion. [Preview Abstract] |
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G1.00081: Superconducting Quantum Interference Devices on Tip Steven Kenney, Jessica Nelson An effective method to investigate the nature of fundamental physics is magnetic field imaging at the nanoscale. To measure a field at this scale necessitates the use of a highly sensitive sensor, the superconducting quantum interference device (SQUID) on tip (SOT), which operates with nanoscale resolution while maintaining operational capacity a similar distance from the system of interest. The SOT thus has the capacity to measure magnetic fields of a single electron. This experiment consists of assembling a vacuum-sealed probe, cooled to near absolutely zero, which will allow us to study and optimize properties of the SOT. Auxiliary aspects of the experiment include setting up a Data Acquisition (DAQ) system to automate our experimental procedure and data collection. Short-term goals include finalizing the assembly of the probe, instrumenting the superconducting amplifier, and confirming the functionality of the SOTs from collaborators in Israel. Long-term research will involve studying high-frequency properties of the SOT and using this information to optimize SOT sensitivity. [Preview Abstract] |
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G1.00082: Laser Deposition of Noble Metal Nanoparticles Nicholas Jenkins, Anatoliy Pinchuk The mechanism behind a novel technique in which lasers can be used as a “pen” that can “write” lines made of metals, such as silver or gold on a substrate is investigated through analytical and numerical methods. The substrate can be glass, plastic, or other suitable materials. These laser deposited metal nanostructures, which exhibit plasmonic behavior, can be used to substantially enhance inelastic scattering of light that can detect small amounts of chemicals and biologically relevant microorganisms. To fabricate plasmonic substrates that can enhance scattered light with the highest efficiency we need to understand the exact physical-chemical mechanism involved. The deposition consists of dropping a solution of silver nitrate on a glass slide and tracing a focused laser across the glass surface. Laser-induced deposition is most likely initiated by the photo reduction of silver ions to silver nanoparticles. Then, particle-surface interactions drive the nanoparticles to the substrate leading to a permanent attachment. To examine the large scale behavior of the depositing nanoparticles, a numerical method known as extended random sequential adsorption (XRSA) was utilized. From the results obtained through XRSA a clearer picture of the laser-induced deposition is developed. [Preview Abstract] |
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G1.00083: Dynamic Compression Science at Sandia's Z Machine Jean-Paul Davis The Z machine at Sandia National Laboratories, the world’s most powerful pulsed-power facility, has been used since 1999 to perform dynamic compression experiments on many different materials. These experiments use the high magnetic fields generated by Z to drive shockless ramp loading, impact shock loading, and, more recently, combined shock-ramp loading to investigate equations of state, phase transitions, and material strength under extreme pressure and temperature conditions. This poster will present the ramped magnetic-pressure drive concept as realized at Z, along with at least three different examples of recent results in dynamic compression science. [Preview Abstract] |
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G1.00084: Visualization of Changing Electromagnetic Backgrounds Melissa Montoya, Paul Arendt This poster presents results from animations which were made of the electromagnetic waves generated when a background magnetic field changes its configuration. The animations were created to accompany work which is being done to investigate the behavior of quantum fields evolving in these backgrounds. In particular, they help illustrate various features of the waves which can have important physical effects, such as those which contribute to particle creation, while the background is changing. [Preview Abstract] |
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G1.00085: Analysis-Based Calibration of a Manual Coil Hand Winding Machine Ava Spangler, Leland "Chip" Spangler, Kathrin Spendier Helmholtz coils are used to make precise magnetic fields, which have a variety of biomedical applications, such as drug delivery through airway mucus via oscillating magnetic nanoparticles. Nanoparticles are particles that are smaller than 100 nm in diameter. In this study, the U.S. Solid manual coil hand winding machine model number NZ-2 was used to develop precisely wound orthogonal coils. The exact calibration of the coil winder is imperative for designing a pair of Helmholtz coils that generates a specific magnetic field. The coil winder was functionalized and calibrated by a series of analysis-based tests. The functional and calibrated manual coil winder is used to design a set of two-axis Helmholtz coils that fits inside Leica’s DMI6000 and DMI3000 inverted microscopes. The coils are used to produce an oscillating magnetic field to rotate magnetic nanoparticles in high viscosity fluids. [Preview Abstract] |
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G1.00086: Exploring Interparticle Purity for Quantifying Entanglement in Binary Systems Jason Saunders Entanglement is a powerful tool in quantum information and quantum technology. Quantifying it can be tricky - different measures are used to capture specific aspects. Interparticle purity is presented as a useful measure of entanglement in binary pure-state systems. It quantifies how much of an entangled system's information is contained within its whole, rather than within its two parts, by computing the purity of the reduced density matrices. We find the maxima and minima of the interparticle purity for a two qubit system, and show that they correspond to separable states and Bell states, respectively. We explore the extension to two qu-nit systems and the relationship with Von Neumann entropy. [Preview Abstract] |
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G1.00087: A Study of Physical and Chemical Transformation of Mutated Gene Molecules Using Thermodynamic and Computational Analysis Yoonjeong Kwon, Andrew Kyung In this paper, a spontaneous DNA mutation was thermodynamically observed to determine whether the chemical or biological transformation can locally lower or increase the enthalpy of the system. An example of spontaneous DNA mutation is deamination of cytosine, in which cytosine turns into uracil through hydrolysis, mutating the DNA molecule while releasing ammonia under a certain condition. But in case of any endothermic reactions, in which heat energy becomes chemical potential energy, the reactions increase the chemical potential energy on the final products. Since the DNA does not exists in isolation but neatly packed together in tight coils, the study of physical stabilization of the DNA molecule after DNA mutation is not easy. In this paper, using computerized medicine and biomedical engineering, the possible methods to analyze and to study the stabilization and kinetics of the DNA mutation are shown. This research uses computational chemistry to calculate the thermodynamic stability of the gene molecules. To determine whether the DNA molecule is locally destabilized by a spontaneous DNA mutation, physical and chemical computational softwares is used to further display the optimized geometry energy levels and calculate each compound model’s theoretical values. [Preview Abstract] |
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