Bulletin of the American Physical Society
2018 Annual Meeting of the APS Four Corners Section
Volume 63, Number 16
Friday–Saturday, October 12–13, 2018; University of Utah, Salt Lake City, Utah
Session G01: Poster Session |
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Chair: David Kieda, University of Utah Room: CSC 205/206 |
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G01.00001: Analyzing Stellar Spectra From Camera Images Cole McKay Miller, Jonathan Price The goal of this project is to develop an attachment between cameras and telescopes which can easily and effectively produce spectral data from images. Rather than using a fiber optic cable, which captures light, but not full images, our design can acquire high resolution images and then extract the image’s spectrum. The design consists of a transmission grating, a 3D printed attachment and housing, python script, and a Sony A7 camera. When looking at an image with our camera and design, the light from the image will pass through the transmission grating and break apart into its constituent spectrum. The camera’s CCD will collect this information and pass it through the python script. The script will measure the intensity of the captured spectrum and plot it as a wavelength vs. intensity graph. Once the image’s spectrum is produced, it can be used in a variety of ways such as studying black body temperatures, determining stellar composition, and studying red shift of astronomical objects. |
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G01.00002: Constraints on the number of X-ray Pulsars in IC 10 from a deep XMM-Newton Observation Jun Yang We report the most sensitive search yet for X-ray pulsars in the dwarf starburst galaxy IC 10, which is known to contain a population of young high mass X-ray binaries. A total of 207 point-like X-ray sources were detected in the direction of IC 10 by a 2012 XMM-Newton observation with a total exposure time of 134.5 ks. We analyzed separately the PN and MOS data. For the most conservative parameters, 5 point sources produced significant peaks in the Lomb-Scargle periodogram (99\% significance). A $\sim$4100 s period seen in all 3 instruments for the black hole (BH) + Wolf-Rayet (WR) binary IC 10 X-1 is probably due to red noise of astrophysical origin. Considering the periods, luminosities, and spatial distribution of the pulsar candidates in the direction of IC 10, they do not belong to the same distribution as the ones in the Magellanic Clouds and Milky Way. This result holds even if the candidates are spurious, since if the Small Magellanic Cloud were placed at the distance of IC 10, we would expect to see $\sim$5 pulsars at $L_x>10^{36}$ \lx ~inside the $D_{25}$ contour, and their periods would be of order 100 seconds, rather than the mostly $\sim$1 s periods for the candidates reported here, which lie outside the main body of the galaxy. |
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G01.00003: Studying the Effects of Masking and Deconvolution Algorithms in Imaging Dilys Ruan, Takahiro Tsutsumi, Kumar Golap Usually when observers get their data from a radio interferometer, they synthesize an image using a deconvolution algorithm they know from experience. Instead, we would like to formally quantify which algorithms might be preferable in certain circumstances, and specifically when masking might be necessary. With four datasets, we have many trials in which we change specific parameters such as: deconvolution algorithm, iterations, number of visibilities (interferometer responses), number of sources, masking, and threshold. Masking helps in situations where the algorithm doesn't have enough information to find a solution image. In this case, if a mask isn't specified, divergence is likely. However, ultimately on a systematic level, it matters more with which deconvolution algorithm one uses. While there are many different types of deconvolution algorithms, we've focused on Hogbom, Multi-scale, and Maximum Entropy Method (MEM). |
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G01.00004: Near Infrared Robotic Observation of Double Star System WDS 13513-3928 Stephen L White, James Gallegos, Grady Boyce, Pat Boyce, Carson Barnett A near infrared robotic observation of the double star system WDS 13513-3928 was performed at the Siding Spring Observatory in New South Wales, Australia—part of the Las Cumbres Observatory Network. The mean position angle (θ) and separation (ρ) were measured to be 51.79° +/- 0.002° and 28.32" +/- 0.001", respectively, and were calculated from a series of twenty images. The mean values obtained, along with historical measurements from the United States Naval Observatory (USNO) and astrometric data collected by the European Space Agency’s (ESA) Gaia satellite, substantiate the claim that the system is likely an optical double system. |
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G01.00005: Measuring the Unresolved Cosmic X-ray Background with NuSTAR Steven Rossland, Daniel Wik The extragalactic cosmic X-ray background (CXB) in the hard band (~3-300keV) encodes the accretion history over all cosmic time of the super massive black holes found in the centers of active galactic nuclei (AGN). Measurements of the flux and detailed spectrum above 7keV from previous missions disagree at the 10-40% level, while the AGN population production at the peak emission (20-30keV) is poorly understood. The X-ray telescope NuSTAR can measure the CXB through its unique design and sensitivity in the band pass of 3-40keV. In order to reliably measure this emission with NuSTAR, certain challenges must be overcome: contamination from local sources, environmental conditions in the satellite’s orbit including activation/fluorescent lines from hard X-rays and soft cosmic rays, and a solar component. This solar component has features of uncertain origin, can dominate the CXB at energies below 7keV, and can vary over time, making it difficult to model. Stacking data when NuSTAR is pointed at both the day and night side of Earth isolates the effective solar spectrum, allowing us to derive an empirical model and keeps it from biasing our future measurement of the CXB. |
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G01.00006: Variations in Elemental Abundance Between Planet Hosting and Non-Planet Hosting Stellar Twins. Devan Peter Anderson, Inese Ivans This research aims to identify potential variations in the elemental abundance of two groups of stellar twins. These stars are considered twins based on their identical temperature and overall metallicities, but are distinguished from one another by either the presence or the lack of planets. The stars selected for this research fit the criteria for twins, and were further related by their spectral lines of Fe I&II. Using Keck Observatory HIRES Archive data we measured the spectral lines in the interactive spectrum analysis code SPECTRE and we measured the abundances with the line analysis and spectrum synthesis code MOOG. By using stellar twins this study has constrained all variables in the abundances of the stars to the single variable of planetary formation. In my presentation I will discuss the results of this research concentrating on the differences in planet hosting stars. The results could shed light on previously unrecognized factors that influence planetary formation. |
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G01.00007: A motion-based search of the outer solar system and beyond with WISE and NEOWISE Teddy Anderson, Benjamin Bromley, Aaron Meisner, Scott Kenyon NASA's WISE satellite has opened up the infrared sky, mapping the cosmos at 3-5 microns over a period of more than eight years. We use time-resolved, coadded W2-band images from WISE, and the follow-on NEOWISE mission to explore an approximately 40x40 square-degree area of the sky. The coadds allow us to probe to a W2-band magnitude around 16 Vega, significantly fainter than in previous work, while retaining the long time baseline needed for motion detection of faint sources. Here we report the (re)discovery of cold brown dwarfs with proper motion above 2 arcseconds per year, and the results of a preliminary search for 'Planet Nine', a hypothesized giant planet in the outer regions of the solar system.
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G01.00008: NuSTAR Observations of ABELL 2163: Constraining Non-Thermal Emission Randall Rojas Bolivar, Daniel Wik Since the first non-thermal detections of Inverse Compton (IC) emission in galaxy clusters at hard X-ray energies, we have yet to unambiguously confirm IC in follow-up observations. Claims of large IC fluxes from the 10' extent of Abell 2163, a massive merging cluster at z = 0.2, make it the next best chance of confirming a previous IC detection with NuSTAR. Additionally, recently available deep XMM data indicate extreme temperature variations (10-20 keV), the hottest of which are likely due to shocks. However, the XMM spectra suffer from variable Galactic absorption across the cluster, which can be avoided with NuSTAR's harder energy band. We find that the global NuSTAR spectrum is consistent with pure thermal emission, with a global temperature of 11.77 keV +/- 0.14 keV |
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G01.00009: Stellar Intensity Interferometry at the StarBase Observatory Orville Oliver Clarke III, Nolan Matthews, David B Kieda Stellar intensity interferometry (SII), combined with modern digital electronics, can be used to perform high angular resolution measurements of hot stars at optical wavelengths. Such measurements can be made using Imaging Air Cherenkov Telescopes (IACT), which are built for the purpose of gamma-ray astronomy. Over the Spring of 2018, a series of observations conducted at StarBase Observatory, located in Grantsville, UT, have shown the feasibility of SII on telescopes similar in design to IACTs. In this poster, I will cover our observation methodology, including the tracking of stars, polarization modulation, and difficulties associated with making accurate correlation measurements. These observations resulted in a marginal detection of the spatial coherence associated with the target sources. |
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G01.00010: The Search for a Shock in the Merging Galaxy Cluster PLCKSZ G200.9-28.2 Daniel Wik, Sarina Etheridge Galaxy clusters are the largest virialized structures in the universe, consisting of hundreds to thousands of galaxies bound together by gravity, with the bulk of baryonic matter contained within the hot plasma diffused between the galaxies, known as the Intra-cluster Medium. These enormous structures are able to grow in size by merging together via violent collisions, arguably the most energetic events since the Big Bang. Mergers heat the tenuous gas by turbulence and shock fronts driven by the dark matter. Shocks are difficult to study directly due to their intrinsically low Mach numbers, and as such are rare events to observe. However, key features such as radio relics produced by synchrotron-emitting relativistic electrons, temperature variations, and surface brightness discontinuities often coincide with their location. PLCKSZ G200.9-28.2 is a merging cluster, discovered by the Planck satellite with the Sunyaev-Ze'ldovich effect, and seen to have a radio relic in the outskirts. We present new, deep observations of this cluster with the Chandra X-ray observatory, including temperature maps and surface brightness profiles to better understand the nature of the merger and the presence of a shock front. |
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G01.00011: Evidence for a High Altitude Haze on Brown Dwarf Melania Pena, Caitlin Murphy, Jacqueline Radigan, Timothy Doyle Brown dwarfs are celestial objects with masses between those of large planets and small stars, that emit primarily infrared radiation. Unlike main sequence stars, brown dwarfs cannot reach high enough temperatures to conduct nuclear fusion within their cores. As a result, brown dwarfs have surface temperatures below 2200 K, at which point silicate clouds can form in their atmospheres. We present overlapping Hubble Space Telescope (HST; Wide Field Camera 3) and Spitzer Space Telescope observations of a variable brown dwarf with patchy silicate clouds in its atmosphere. The brown dwarf varies in brightness as it rotates, with an amplitude of ~5% from 1.1-1.7 microns (HST), and ~2.5% at 3.6-microns (Spitzer). Using a Mie-scattering model we determined that a lognormal distribution of sub-micron size grains at a high altitude in the atmosphere can approximately reproduce the observed variations at all wavelengths. |
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G01.00012: Using AdaBoost Tree to Improve the Efficiency of the Background Rejection Algorithm of HAWC Observatory Sage Yeager The High Altitude Water Cherenkov (HAWC) observatory is a gamma-ray observatory located on the flanks of the Sierra Negra volcano near Puebla, Mexico. The primary goal of HAWC is to measure gamma-rays in the energy range between few hundreds GeV and tens of TeV. However, the HAWC observatory is also sensitive to cosmic-rays, which create a strong background signal for the gamma-ray signal. Removing this background signal is paramount to detect gamma-ray sources. As such, we are investigating the possibilities of using machine learning algorithms to improve the efficiency of the HAWC background rejection algorithm. I will present our progress implementing an AdaBoost decision tree algorithm to simulated HAWC data and ongoing work to test this algorithm on the HAWC real data set. |
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G01.00013: Constraining Cosmological Parameters through the kSZ effect Jonathan David Davis, Rachel Bean This project seeks to improve upon previous FORTRAN 90 software used to model the measurements and statistics of large scale galaxy clusters. It implements the python wrapper for the Core Cosmology Library (LSST DESC, in preparation) for several core calculations. It then implements a custom python script to model the measurements and statistics of the mean pairwise velocity of large galaxy clusters as outlined in Mueller et. al 2015. Care has been taken to ensure maintainability and reusability of the code by using an object oriented structure. Computing performance was also taken into account through code optimization and parallelization, moderately improving single thread calculations while drastically improving performance on larger multi-core processors. |
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G01.00014: Investigating Winter-time Mesospheric Gravity Waves Variations Observed at ALOMAR (69°), Norway David Soward, Michael J Taylor, Yucheng Zhao, Dominique Pautet Atmospheric gravity waves generated in the lower atmosphere propagate upwards and carry energy and momentum into the upper atmosphere strongly affecting the mesospheric temperature structure. The Advanced Mesospheric Temperature Mapper (AMTM), developed at Utah State University (USU), is designed to study high latitude mesospheric dynamics by measuring the OH (3,1) band intensity and temperatures even with the presence of Aurora. In 2010, the AMTM was deployed at Arctic Lidar Observatory For Middle Atmosphere Research (ALOMAR) in northern Norway, (69° N) and has operated automatically during the winter season (September through April) until 2017. High quality winter-time mesospheric temperature and OH band intensity data were obtained from this high latitude site. In this study, we will utilize the 7 seasons of zenith temperature measurements from ALOMAR to investigate the intra-seasonal and inter-annual variations of gravity waves during the winter season. |
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G01.00015: Investigation of Two Anomalous Thin Layers Descending Through the Lower Mesosphere and Upper Stratosphere Houston Dale Bentley, Vincent B Wickwar On the night of February 19-20, 2004 at Logan, Utah (41.74 N, 111.81 W), LIDAR observations with a Rayleigh scatter LIDAR revealed two anomalous thin layers. These layer are roughly 1.5 km thick. The first layer was detected at 11 pm local time and descended from approximately 55 km to 30 km in a span of 7 hours. The second layer was detected around 6 am and descended from roughly 55 km to 41 km over a span of 24 minutes. Approximations were made about the rate of descent of the layers to be nearly linear. Though the densities and radii of these layers are not known, estimates for these quantities are made by comparing the layers’ rates of descent to the rates of known aerosol layers. The source of these layers is speculated to originate from an object entering high in the atmosphere and breaking up lower in the atmosphere. |
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G01.00016: Exploring inner core structure beneath the Pacific Ocean using US Array data Rashni T Anandawansha, Lauren Waszek Inner core plays an important role in governing Earth's dynamics. As Earth cools, the inner core grows slowly over time,releasing latent heat and lighter elements which drive convection in the outer core, and thus help power the Earth’s geodynamo. Seismically, the inner core is characterized by complex features; the dominant structures being an east-west asymmetry in seismic velocity and attenuation, and cylindrical anisotropy. The anisotropy appears weak at the inner core boundary, but stronger at depths; it is unclear how the shallow anisotropic structure relates to the deeper inner core. Linking these layers is important to understand the evolution of the anisotropy over time.The structure of the inner core is not well constrained at depths of 100-200 km beneath the inner core boundary, which is an important layer to understand the changes in the processes influencing anisotropy. We use a combination of array stacking techniques and synthetic seismogram modeling to separate and identify the phases. We initially focus on the region in the vicinity of the hemisphere boundary beneath the Pacific Ocean. By mapping the structure in this region, our results will allow us to better constrain the evolution of the hemispheres and anisotropy with depth and hence over time. |
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G01.00017: Comparison of Mesospheric Densities and Temperatures from the SABER Instrument on NASA’s TIMED Satellite and USU’s ALO Rayleigh-Scatter Lidar Andrew Curtis, Jonathan L. Price, Vincent B. Wickwar The Atmospheric Lidar Observatory (ALO) at USU has a Rayleigh Scatter Lidar (RSL) that operated from 1993 – 2004. It took data on the mesosphere, from 45 km to about 95 km, which was used to deduce absolute temperature and the relative neutral density. Recently, the analysis was modified to convert these relative neutral densities to absolute neutral densities. This used reanalysis models to provide absolute densities at 45 km to which the relative profiles could be normalized. With that, composite climatologies of densities and temperatures have been made using the lidar data. Similar climatologies can be made using data from the SABER instrument, on NASA’s TIMED satellite, which was launched in 2001 and has been operational from 2002 to the present. TIMED data from a 5x5 degree grid centered on Logan, UT, has been used to compare to nighttime temperatures and densities from the lidar. The similarities and differences are presented. |
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G01.00018: Correlating All Sky Images with Weather Data at the Magdalena Ridge Observatory E. Garcia, M. J. Creech-Eakman, D. Klinglesmith The Magdalena Ridge Observatory takes nightly pictures with an all-sky camera for cloud coverage. An automated approach was developed to analyze the images and gather data from them. A multi-program system first located all images in the archive, analyzed average photon counts per pixel, and categorized them into either a “moon” or “no moon” folder depending on the counts. Next, images in each of the folders had different threshold counts to determine the presence of clouds in the image by analyzing standard deviation. In the “moon” files this is accomplished by masking out the moon. Finally, images are examined along with the numeric statistics. Results to date show that the analysis agrees with visual inspection ~70% of the time for images with the moon, and ~88% of the time when the moon is absent. The next steps will be to correlate the cloud coverage statistics with other measurements to determine how many nights per year are viable for astronomical research. |
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G01.00019: Building Payloads for the Colorado Space Grant Consortium (CSGC) Demosat, High Altitude Student Platform (HASP), and a High-Powered Rocket. Paloma Juarros, Nathaniel Todd, Ryan Ford, Jodi James, Charles Hakes Three payloads were designed, built, and flown on three different platforms. Each payload was mounted to a sled inside a cylindrical tube, allowing the payload to be removed, serviced, and replaced with minimal effort. Primary components included an experiment to measure sky polarization, a power monitoring system, a thermal control system, and a Mobius camera. The first platform was for the Colorado Space Grant Consortium (COSGC) DemoSat high-altitude balloon flight. This lightweight payload had a mass of 804 gm and rose to 32 km before the balloon burst. The second platform was a high-powered rocket powered by an Aerotech J401FJ-L solid propellant motor. It reached an altitude of 1.4 km and exceeded 10 Gs of acceleration. Redundant electronics to control drogue and main parachute deployment were included. The third platform was the High Altitude Student Platform (HASP), supported by the Louisiana Space Grant Consortium (LaSPACE), and launched from the Columbia Scientific Balloon Facility (CSBF) in New Mexico. This flight was at an altitude of 37 km for 9 hrs. This version of the payload used an external power source and included telemetry capability. Data from the Power, Thermal, Polarization, and Camera systems are presented and discussed. |
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G01.00020: Instability Index and Saturation Fraction in Mid-Latitudes Sooraj Bhatia, Stipo Sentic, Zeljka Fuchs A correlation has been observed in the tropics between the instability index and the saturation fraction. The authors look to see if this correlation holds at mid latitudes in convective systems. Atmospheric sounding data from all 66 stations in the U.S. between the latitudes of 30 and 60 degrees from the years of 2007 to 2017 are utilized for this analysis. This is a preliminary analysis to determine if a full study of 30 years of past sounding data is warranted. If this correlation is found to exist in mid latitudes, the findings of this study could be used to improve climate models leading to more accurate predictions of both weather and climate change. |
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G01.00021: Cascaded second-order nonlinearity for ultrashort pulses control and characterization Ning Hsu, Luke Horstman, Jean-Claude Diels Crystals with second-order nonlinearity are commonly used for wavelength conversion. Cascaded second-order nonlinearity, which involves placing two nonlinear crystals in sequence, provides wavelength conversion over a more flexible range. In this paper, two different applications of cascaded second-order nonlinearity are established. First, a novel ultrashort pulses diagnostic technique, Cascaded nonlinearity inside a spectrometer (CaNIS), is proposed, demonstrated experimentally and verified by simulation. Second, a new remote spectroscopy laser system using passive negative feedback, and three cascaded second-order nonlinear crystals is proposed. The cascaded nonlinearity is used to create a broad spectrum which is essential for the ability to temporally focus the pulse beyond 10km. This laser is expected to deliver 100mJ, 1ps, UV pulses. |
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G01.00022: Measuring the Frequency-dependency of the Critical Field of Carrier Multiplication in GaAs Benjamin Ray Heiner, Jeremy A. Johnson For several years, the clock speed of silicon-based computer processors (and other electronics) has plateaued at single-digit gigahertz frequencies, leaving room for other materials to be explored as replacements and improvements. Diodes and transistors function due to field-induced carrier multiplication in the semiconductor material, and silicon devices appear to have reached their speed limit. Material properties, such as the critical field for carrier multiplication, are frequency dependent. Testing the possibility of improvement in diode switching times using light in the terahertz (THz) frequency range can offer a solution. Intense THz radiation can be used to excite carriers in semiconductors, testing if the switching times can be orders of magnitude faster. Currently, the electric fields we generate are not strong enough to excite carriers into the conduction band, so we use arrays of micron sized meta-structures deposited on the surface, locally enhancing the THz electromagnetic radiation, making the field strong enough to excite electrons in GaAs. Our goal is to help develop materials and understand properties central to realizing high-speed electronics. Here we show THz frequency-dependent measurements of the critical field of carrier multiplication in GaAs. |
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G01.00023: Wavelength Metrology with Webcams Jason N Porter, Jonathan Treter, Jarom S. Jackson, Dallin S. Durfee A precise wavelength meter is crucial to many experiments but can cost upwards of $20,000. We are developing a method of using a CCD camera to measure the wavelength of a laser. Our proposed device is robust, inexpensive, and projected to yield picometer-level precision. As collimated light passes through the color filters over each pixel, it undergoes a measurable etaloning effect. By creating a precise spectral response model for many pixels, we can use a least squares error method to calculate the wavelength of the laser. |
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G01.00024: A dual-species hybrid MOT/Paul trap Tyler Bennett, Sarah Hill, Robert Sprenkle, Scott Douglas Bergeson We report on progress to create a hybrid dual-species calcium and ytterbium magneto-optical trap (MOT) superimposed onto a linear Paul trap. This configuration will allow us to trap neutral atoms in the MOT, ionize them using ns-duration pulsed lasers, and then trap the resulting plasma in the Paul trap. By driving the trap at two frequencies we will eliminate centrifugal separation inherent in simultaneous trapping of different mass ions. The primary goal of this experiment is to measure collisional momentum transfer between the Yb+ and Ca+ ions as a means of determining the Coulomb logarithm in a strongly coupled plasma environment. Using carefully aligned probe laser beams and by spatially imaging ion fluorescence, we anticipate being able to distinguish between the coherent ion micromotion and the thermal ion motion in the plasma. |
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G01.00025: Optical Precursor Polarization Rotation in a Magnetic Field Mark Watkins, Jonathan R. Gilbert, Jacob Roberts We apply a magnetic field to an ultracold gas and by applying light turned on faster than the atomic dipole response time, we observe the time development of polarization rotation through the Faraday effect. The details of the time development depend on the atomic dipole lifetime, the optical thickness of the gas, the spin polarization of the gas, and the strength of the applied magnetic field. Experimental and theory results are presented. |
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G01.00026: Microbial communities in Anaerobic Digestion at different temperature regimes: Mesophilic and Thermophilic Dominique Madrid Anaerobic digestion (AD) is described as a series of biological processes where microorganisms break down to biodegradable material in the absence of oxygen. There are three temperature regimes which the microbe bacteria can inhibit at psychrophilic (<25°C) low, mesophilic (25°C - 40°C) moderate, and thermophilic (50°C - 60°C) warm environments. This study will focus only on the mesophilic and thermophilic regimes where it is the most likely we find methane production. The conversion process of organic matter to biogas (methane) during AD is most effective when a consortium of microbial activity mineralizes organic matter. Degradation of organic material is a crucial and often limiting factor of AD and the role of diverse microorganism populations responsible need to be analyzed. This discussion will focus on the reactions at each phase and which microbes are present during the conversion process. Anaerobic digestion acquires different limiting factors under mesophilic or thermophilic temperature regime. The reaction rates during each phase transformation and their temperature regimes are analyzed in terms of thermodynamic energy transfer. |
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G01.00027: Microtubule stability and mechanical rigidity at high temperatures Abhimanyu Sharma Microtubules (MT) are polymers of α and β tubulin and constitute a significant part of eukaryotic cell’s cytoskeleton. They are tubules, ~25nm in diameter and can extend up to several tens of microns in length. They can be crudely modeled mechanically as rigid rods but many finer details linked to their structural anisotropy remain controversial. Understanding these finer mechanical properties is important biologically as well as for bio-nano engineering applications. The effect of temperature variation on mechanical properties of MT is yet to be fully understood. We will discuss the flexural rigidity of taxol-stabilized MTs as a function of temperature and the implications of our results for how MT structure impacts their temperature stability. We’ve also tested the limits of MT stability at high temperatures and different factors that contribute to it.
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G01.00028: Using a Deformable Mirror to Enhance Super Resolution Fluorescence Microscopy for Biological Imaging Sanduni Fernando, Jason Martineau, Jordan M Gerton Super resolution fluorescence microscopy is a possible candidate for simultaneous multicolor live-cell imaging of proteins through wavelength sensitive point spread functions (PSF). Deformable Mirrors (DM) are used in Astronomical telescopes to correct for wave front aberrations, which seems to be an interesting approach to be burrowed in order to increase the sensitivity of PSFs. DM will allow us to optimize differences in the PSFs across narrow ranges of wavelengths. Then proteins tagged by similar type of dyes could even be distinguished. The DM will be characterized using a Twyman Green Interferometer with polarizing optics in which an interferogram corresponding to the surface of the DM is obtained. Then it will be attached to the current fluorescence microscope to introduce a correction to the fluorescence light beam from the protein sample. High sensitivity of interferograms is expected to minimize errors that would consequently enhance color recognition. The DM helps to engineer PSFs that are information-optimal in terms of space and wavelength dimensions. |
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G01.00029: Matrix and Grid-Based Methods for Quantum Bound States Kevin John Randles, Daniel V. Schroeder We investigate matrix and grid-based methods for finding the bound states of multidimensional quantum systems. In the matrix method, we expand the wave functions in terms of products of sine-wave basis functions, then diagonalize the resulting Hamiltonian matrix. In the grid-based method, we solve a discretized version of the Schr\"{o}dinger equation using a relaxation algorithm based on the variational principle. We find that the matrix method is preferred if high accuracy is needed, while the grid method is easier to code. Although these methods can be used for arbitrary trapping potentials, we focus on a system consisting of a particle in a two-dimensional double triangular well. This potential models a pair of vertically coupled quantum dots embedded within an AlGaAs barrier material. Quantum dots are of current research interest because their optoelectronic properties can be precisely tuned through the modification of their composition and geometry. |
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G01.00030: Chemical Reactions Modeled Using Classical Molecular Dynamics Jeremy Walker, Daniel V. Schroeder We have created a two-dimensional molecular dynamics simulation to model the formation and dissociation of diatomic molecules using classical mechanics. This simulation is designed to be an educational tool used in lower-division physics or chemistry classes. The atoms interact via Lennard-Jones potential energies, while the chemical bonding is controlled by an additional short-range potential between active sites near the atoms' edges. Each active site is free to rotate around the atom, so bonding requires that atoms be in the proper orientations. As expected, most atoms form bonded pairs at sufficiently low temperatures. Somewhat counterintuitively, however, molecules in the gas phase tend to dissociate at temperatures well below the characteristic temperature determined by the bonding potential depth. |
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G01.00031: Numerical investigation of entangled two-particle quantum systems Peter Isaac McFarland, Daniel V. Schroeder Using a grid-based relaxation algorithm, we find numerical solutions to the time-independent Schrödinger equation for some interacting two-particle systems. The first system is two particles trapped in an infinite square well with a contact interaction that varies in strength. The results show the ‘fermionization’ effect, in which the two particles are in a symmetric state but as they interact more strongly the energies become closer to those of an antisymmetric state. The second system is the helium atom, where we focus on states with spherical symmetry and neglect angular correlations. We obtain the helium ground-state energy to an accuracy of less than one percent, and obtain the 1s2s excited-state energies to even higher accuracy. This numerical method is easy to understand and is accessible to undergraduate physics students. It provides a useful tool for developing intuition in quantum mechanics and for investigating non-separable multidimensional systems. |
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G01.00032: High Precision Numerically Assisted Diagrammatic Calculation of Transport on Lattices. Benjamin Cochran, David Dunlap In diffusion on a lattice with equal rates between sites, the solution can be modeled by a random walker by taking the number of ways the hopper can go to each site divided by the total different ways it can go in n hops and summing that over n from 0 to infinity, with each term weighted by the probability to make n hops. By introducing self-hops, where the walker returns to its initial site, this method can be applied to heterogeneous lattices having different rates between sites, as well as lattices with unusual boundary conditions. Due to the similar structure of the differential equations for diffusion and masses attached by springs in the Laplace domain, this method can also be applied to the latter situation. |
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G01.00033: Fabrication and Testing of BN-Graphene Mechanical Resonators Deric Session, Rohit Kumar, Harrison Paas, Vikram V Deshpande* Mechanical resonators are promising for many applications such as frequency filters as well as for studies of fundamental physics. We report on the fabrication process for BN-graphene mechanical resonators, this process employs the capillary force assisted clean-stamp transfer method. We also discuss the testing of our mechanical resonators which involves the measurement of resistance by gate voltage and radio frequency readout using a vector network analyzer to detect resonance. |
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G01.00034: Comparison of spin and charge transport in organic semiconductors Matthew Groesbeck, Haoliang Liu, Evan Lafalce, Dali Sun, Hans Malissa, Marzieh Kavand, Christoph Boehme, Zeev Valy Vardeny We have investigated spin and charge transport processes in organic semiconductors (OSECs) in order to compare spin-transport and charge-transport in these materials. For the spin transport we measured the spin diffusion length, λs via the inverse spin Hall effect (ISHE) in NiFe/OSEC/Pt trilayer devices, whereby a pure spin-current is generated in the polymer by spin-pumping from the ferromagnetic layer (NiFe), then diffuses to the Pt layer where it is converted into an electrical signal due to the strong spin-orbit coupling of Pt. For the charge transport we measured the carrier mobility of photogenerated charges via the time of flight technique. We also determined the (longitudinal) spin relaxation time, T2 by pulsed EPR method, which allows us to calculate the spin diffusion coefficient Ds from λs. Finally we relate Ds to the charge diffusion coefficient Dc, which is determined from the charge mobility measurements via the time-of-flight method. |
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G01.00035: Ab Initio Studies of the Electrochemical Properties of β, R, and 𝛾-MnO2 Polymorphs Birendra Ale Magar, Igor Vasiliev, Jonathon Duay, Timothy N Lambert At a low depth of discharge, the performance of rechargeable alkaline Zn/MnO2 batteries is governed by the concomitant processes of hydrogen ion insertion and electro-reduction in the solid phase of 𝛾-MnO2. Ab initio computational methods based on density functional theory were applied to study the mechanism of hydrogen ion insertion into the pyrolusite (𝛽), ramsdellite (R), and nsutite (𝛾) MnO2 polymorphs. It was found that the hydrogen ions inserted into 𝛾-MnO2 initially occupied the 2x1 ramsdellite tunnels. The study showed that the insertion of hydrogen ions into the 1x1 pyrolusite tunnels of 𝛾-MnO2 created instability leading to the breakdown of the crystal structure of 𝛾-MnO2. |
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G01.00036: Electrical and noise characterization of perovskite solar cells at different temperatures Logan Joseph Draper, Kevin Ray Davenport, Mark Hayward, Andrey Rogachev Organic perovskite solar cells are an important emerging technology with the capability to compete with Silicon and other solar cells. Here we perform I(V) and noise characterization of the solar cells with the composition (𝐶𝐻3𝑁𝐻3𝑃𝑏𝐼3) in the temperature range T=100-310 K and at different levels of light intensity. The studied solar cells display very strong memory effect, that is the current via devices depended strongly on the past history of the light exposure and voltage variation. The memory effect becomes progressively stronger at lower temperatures. To mediate this effect prolonged light exposure (30-60 min) was performed before the start of each I(V) run. We found that the I(V) characteristics display clear deviation from the classical exponential variations. Nevertheless, the gross characteristics were consistent with the “text-book” behavior: the open circuit voltage was roughly independent of light intensity and closed-circuit current was proportional to the light intensity. We will also present and discuss the noise spectra of the devices. |
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G01.00037: Effects of Rashba spin-orbit coupling on low energy magnetization dynamics of the Hubbard model Christopher Ard, Hua Chen Magnetization dynamics is conventionally studied using the Landau-Lifchitz-Gilbert (LLG) equation, which originates from quantum mechanics of electron spins, but can most of the time be used without referring to the electronic degrees of freedom that give rise to the magnetism. |
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G01.00038: Terahertz Waveform Considerations for Driving Lattice Vibrations into the Anharmonic Regime Brittany E. Knighton, R. Tanner Hardy, Courtney L. Johnson, Lauren M. Rawlings, Joel T. Wooley, Coraima Calderon, Alexa Urrea, Jeremy A. Johnson The potential energy surface (PES) is a manifestation of the forces that connect elements together and govern nearly all material properties, from thermal expansion to phase transitions to energy transport, making the PES central to condensed-matter physics and ultimately device design. The shape of the PES in solids has only recently begun to be determined experimentally. We extract the PES along the E phonon-polariton vibrational coordinate in LiNbO3 using high-field terahertz (THz) spectroscopy, and optimize the THz waveform to drive atomic motion to large amplitudes by comparing three different THz generation crystals. To maximize atomic displacement, we show that the spectral amplitude at the resonant mode frequency (3.8THz) is more important to consider than the THz peak electric-field strength. We confirm this with Z-scan and 2D THz pulse shaping measurements and provide important guidance for future experimental investigations of the anharmonic PES in solid materials. |
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G01.00039: Strain engineering of flat bands in trilayer graphene Jameson Berg, Chuankun Liu, Ryuichi Tsuchikawa, Vikram Deshpande This is the preliminary work into our study of strain effects on the flat bands present in aligned ABC stacked trilayer graphene (TLG)/Hexagonal boron nitride (hBN) heterostructures. The flat bands are a result of the Moiré patterns created between the TLG and hBN due to the small lattice constant mismatch and nearly 0 twist angle between the layers. Recent work has shown that these heterostructure have gate-tunable Mott insulating states at partial filling. We aim to expand on these results by applying stain to a ABC TLG/hBN heterostructure using a flexible substrate in place of the standard silicon substrate. The application of strain will modify the interlayer coupling between the TLG and hBN leading to a new platform to studying flat band physics. |
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G01.00040: Neuromorphic Computing with Superconducting Nicolas Franco A superconducting ferroelectric hybrid device was constructed for the purpose of demonstrating that said it could be realized as a "synapse" in the context of neuromorphic computing. The results of experiments performed at cryogenic temperatures show that switching the polarization of the ferroelectric material does in fact modulate the critical temperature of the niobium as a consequence of the ferroelectric field effect. What is to be done with these functioning hybrid devices, given the success of the experiments, is also discussed. |
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G01.00041: Search for Majorana zero modes in a triangulartopological superconductor island Aidan C Winblad, Hua Chen With the goal of designing a flexible platform for performing braiding oper- |
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G01.00042: Effects of Radiation on the Electrostatic Discharge of Polymers Kip Quilter, Megan Loveland, Alexandra Hughlett, JR Dennison Measurements have been made to determine if an increased density of localized defects generated by ionizing radiation affects the electrostatic breakdown of highly disordered insulating materials. Five highly disordered polymeric materials were chosen (Polyether ether ketone, Kapton, Fluorinated ethylene propylene, Polypropylene, Low-density polyethylene ) for their different tolerance to radiation. These polymers were exposed to 5kGy of penetrating beta radiation in vacuo to change the density of the localized defect states throughout polymer. Increasing density of localized states were known to enhance the hopping conductivity of polymers. Electrostatic discharge (ESD) field, strongly viewed as an extreme limit of conductivity, is therefore expected to be decreased by radiation induced defects. The breakdown of the polymers is measured under vacuum in a parallel plate geometry. In a standard ramp up test, the voltage is increased until a large jump in the current is observed. Measurements were made on unirradiated, irradiated, and irradiated samples that had been exposed to moist air for an extended time to determine the effects of radiation on ESD and if a sample is able to recover from radiation by being exposed to oxygen and water from the atmosphere. |
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G01.00043: Temperature dependence of plasmon-enhanced photocarrier generation and diffusion in single InGaAs/GaAs quantum well Chih-Feng Wang, Sadhvikas Addamane, Kevin Malloy, Terefe Getaneh Habteyes The optical plasmonic properties of metal nanoparticles have been used for enhancing the rate of photoabsorption and photoemission by molecules and semiconductors. In this work, we exploit the plasmonic effects for understanding the dynamics of photocarriers using single InGaAs quantum well (SQW) confined in GaAs barrier by placing plasmonic colloidal gold nanorods (AuNRs) on the GaAs capping layer. This coupling geometry creates enhanced near-field that is tightly localized at the AuNR-GaAs interfaces. As a result, the exciton generation is enhanced at the interface by the local field, and the carrier diffusion and recombination dynamics as a function of temperature can be studied by measuring the photoluminescence (PL) of the InGaAs that is embedded inside the GaAs. We compare the PL of the SQW with and without the AuNRs from 10 K to room temperature and observe that the PL enhancement factor and spectral linewidth peak at certain temperatures depending on incident excitation intensity. We use this trend to study the temperature dependence of carrier diffusion as well as the competition between radiative and nonradiative recombination rates with increasing temperature. |
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G01.00044: Light-fueled High Energy Reactions Enabled by Diamond Tirzah Fougner, Jonathon Barkl, Franz Koeck, Anna M Zaniewski, Robert J Nemanich The enormous power available from the sun has the potential to not only supply electricity, but also fuel high energy chemical reactions that currently depend on fossil fuels to achieve the required high pressure and temperature. In this project, we utilize unique properties of diamond in conjunction with ultraviolet and visible sources of light to generate electrons solvated in water. Enabling this electron generating process is the negative electron affinity of the hydrogen-terminated diamond surface. These electrons are used to fuel the high energy reaction of breaking the nitrogen-nitrogen bond and reducing nitrogen to ammonia. This process could also be used to reverse combustion to make fuels from carbon dioxide. Our results confirm that ammonia is produced by this mechanism from nitrogen gas using both visible and ultraviolet light. |
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G01.00045: Real-time Video Processing of Arcing Events to Determine Coincidence JR Dennison, Gregory Wilson, Jonh c Mojica Decena, Brian D Wood A system has been developed and tested for real-time monitoring of environmentally-induced electrostatic discharge events to test spacecraft component and material survivability. Simultaneous detection by several parallel methods in coincidence, enhances event detection, minimizes false signals, and collects complementary information to determine arc location, intensity, and timing. This research focuses on four computer-interfaced video cameras which provide spatial and temporal detection of visual arcing from the surface of various elements. A real time processing solution was developed which can calculate integrated intensities, sensitively detect intensity threshold events, and store relevant video frames from these threshold events. Post processing of this data can generate activity maps and give detailed threshold event information. This selective approach not only saves vast amounts of disk space and post processing time, but it facilitates real-time monitoring of month long experiments. An experiment which induces arc on insulating dots on a conductive substrate using high-energy beta radiation from a Sr90 source in the Space Survivability Test vacuum chamber was performed to demonstrate the quality of captured data and the effectiveness of the analysis methods. |
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G01.00046: PIN Diamond Diode Detectors for Alpha Radiation Holly Johnson, Anna Zaniewski, Jason Holmes, Ricardo Alarcon, Manpuneet Benipal, Franz Koeck, Harshad Surdi, Robert J Nemanich Semiconductors have long been used as radiation detectors for detecting particles such as protons, neutrons, or alpha particles. Historically these semiconductor detectors have been made of silicon; however, silicon-based detectors are damaged over time by radiation and in some cases must be frequently replaced, require periodic calibration, and are susceptible to thermal noise due to its small bandgap. In this project we demonstrate a PIN diamond-based detector (PIN: p-doped, intrinsic, n-doped). Diamond is a wide bandgap semiconductor with a bandgap of 5.45 eV. PIN diamond has a built-in electric field, allowing it to detect particles without an external bias. The PIN structure has a number of advantages. Without an external bias, the signal will have less noise; also, the device can be forward biased to remove any charge build-up. Compared to silicon, diamond is less susceptible to thermal noise and is more robust to radiation damage, making it advantageous in energetic, high temperature environments. |
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G01.00047: Moving Magnet Pump for Transportation of Liquid Sodium Rachel Day A renewed interest in fast neutron reactors has opened a need for better understanding of pump design with hazardous fluids, such as liquid sodium. When these fluids are used as coolants in the reactors, moving magnet induction pumps have shown to be beneficial with their simplicity in design and repair, as well as their potential to perform at a higher efficiency than other electromagnetic (EM) pumps. The use of strong permanent magnets to produce a traveling magnetic field eliminates the need of windings in standard EM 3-phase induction pumps. A moving magnet pump has been designed, constructed and will be tested to move liquid sodium at Fort Lewis College in Durango, CO. Assessing efficiency of the Samarium Cobalt (SmCo) and Neodymium Iron Boron (NdFeB) magnets in the pump will be based upon measurements of pressure-flowrate characteristics while varying the type and amount of magnets, motor speed, and fluid flow through a test loop. |
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G01.00048: Creating a database of Yang-Mills Solutions for the Differential Geometry package in Maple Eli Atkin, Alan Parry, Ryan Bevan Yang-Mills theory seeks to describe the behavior of elementary particles using non-Abelian Lie groups and has successfully described the unification of the electromagnetic, and weak forces as well as form a good description of quantum chromodynamics. Because of this, it is vital for understanding the Standard Model of Particle Physics. The main goal of this project is to make these solutions accessible for anyone desiring to work with and use various SU(2) Yang-Mills solutions, by creating an easily accessible database of solutions and their properties. This database will be available as a free package for the sophisticated Computer Algebra System called “Maple”. Initially the database will have 32 solutions and there are plans to continually add to this database in the future. The solutions are first input into Maple so that the Connection One-Form for each solution can be found and added to the database. Various properties presented in the paper for each solution are then tested and catalogued alongside the Connection One-Form. This project provided an opportunity for the students involved to learn valuable skills such as experience with maple, and a early introduction into Differential Geometry which is rarely seen in a undergraduate education. |
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G01.00049: Multi-beam plasma generation of terahertz radiation: experiments and modeling Clayton D. Moss, Shayne A. Sorenson, Steven K. Kauwe, Jacob D. Bagley, Jeremy A. Johnson We demonstrate two experimental schemes for plasma-based terahertz (THz) generation using ultrafast laser pulses. In one scheme three laser pulses with incommensurate wavelengths and comparable relative powers are used. The three colors include 800 nm and a variable combination of the IR signal and idler outputs from an optical parametric amplifier. Stable THz is only generated when all three colors are present, with little power or spectral dependence on the selection of signal and idler IR wavelengths (range of 1300-2000 nm). In another experiment, we show that the THz emission of a plasma formed by a commensurate two-color pulse (containing a near IR frequency and its second harmonic) can be enhanced by the addition of an 800-nm pulse. We observed enhancements of the THz electric field by a factor of up to 30. The dependence of the THz electric field enhancement factor on the powers of the two-color and 800-nm beams is considered. Numerical calculations done using the well-known photocurrent model are in good agreement with both experimental results. These studies help suggest future avenues of improvement in practical table-top plasma generation of THz. |
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G01.00050: Predicting Student Success: Learner Type Characteristics and Self-Identification Sean Tierney, Michael DeAntonio In a previous study presented at the 2009 Frontiers in Education conference, “A New Set of Learner Classifications for CSET”, a new set of learning types were postulated and found to indicate a difference in the way those learner types handle concepts in physics. This poster will discuss a proposed research project designed to further examine these learner types, called “Connectors”, “Mavens”, and “Salespeople”. In the proposed study, interviews will be conducted with students in an introductory physics class to give insight into these learner types, elaborate upon the differences in learning characteristics of the types, illuminate upon the importance of self-identification from the previous study, and open new avenues of research in this area. |
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G01.00051: Imaging and Mapping of Quantum-Like Behavior in a Hydrodynamic System Clayton Orback, Tyler Onufrak, Hope Dannar, Maya M Davidson, Jan Chaloupka A pilot-wave hydrodynamic system consists of a small droplet of silicone oil that is self-propelled across a vibrating bath of the same liquid. Bouncing vertical motion and "walking" horizontal motion of the droplet can be achieved with careful control over the frequency and amplitude of the oil bath oscillation. The observed “walking” motion is due to the interaction of the droplet with the waves that it generates as it bounces off of the vibrating liquid surface. This system provides a compelling macroscopic analog to the Bohmian pilot-wave interpretation of quantum mechanics. We present results from our hydrodynamic system, including efforts to observe single-particle interference, diffraction, and wave-guide behavior. |
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G01.00052: Periodic Solutions to Two Magnetic Sphere Interactions Bo Johnson, Boyd Edwards The purpose of this research project is to solve the equations of motion for two |
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G01.00053: Which States Violate Bell’s Inequality? Matthew Lawyer, Jean-Francois Van Huele Bell’s inequality provides a theoretical test for local realism in nature. Experimental tests of this inequality have been carried out which show beyond reasonable doubt that local realism is incompatible with certain quantum states. What are the characteristics that set these states apart? I study the Clauser-Horne-Shimony-Holt (CHSH) inequality, a variation of Bell’s inequality, and outline my attempts to characterize the states which violate it. I discuss three methods and their associated difficulties: Symbolic manipulation using calculus, symbolic manipulation using linear algebra, and numerical solution using supercomputing resources. |
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G01.00054: The Future of Quantum Computing Benjamin B Szamosfalvi, Jean-Francois S VanHuele Quantum computers are hailed as the next major step in quantum technology in the general public’s view. Quantum computers can arguably solve certain problems that classical computers cannot. However, there are several difficulties with building and implementing a commercial level quantum computer. Such difficulties include decoherence, the limited number of algorithms, and the lack of computer framework. We will examine the future of quantum computers and the factors that currently limit their viability. |
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G01.00055: Carbon nanotube synthesis by feeding carbon and Fe precursor simultaneously T.-C. Shen From the perspective of hetero-epitaxy, the diameter, wall number, and chirality of carbon nanotubes (CNT) should be dictated by the dimensions and facets of the catalyst nanoparticles (e.g., Fe, Ni, Co). Even without being able to control the catalyst facets, practitioners can synthesize mm-long single-walled CNTs from a pre-deposited film of catalyst less than 1-nm thick on a flat substrate. However, this approach is not optimal for CNT synthesis on nanoparticles, which is desirable for gas-phase catalysis applications. Chemical vapor deposition of Fe simultaneously with carbon feedstock offers a solution to this challenge.[1] By correlating the input Fe/C ratio with the CNT ensemble morphology and individual CNT structures, new insight into CNT formation can be obtained.
[1] T.-C. Shen, et al. Diamond & Related Materials 88, 230-236 (2018). |
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G01.00056: BLS Backscattering Experimental Setup Designs and Magnetic Measurements of Thin Films Rachel Tenney, Grant Riley, David Marchfield, Katherine Nygren, Mitchell Swyt, Kristen S. Buchanan Magnetic thin films are important for a variety of applications that include digital storage and information technology. We are particularly interested in multilayered samples with a perpendicular (out-of-plane) anisotropy and an interfacial DMI (Dzyaloshinskii-Moriya interaction) that can promote the formation of topologically-protected spin textures called skyrmions. We are using Brillouin light scattering (BLS) to measure the DMI and vibrating sample magnetometry (VSM) to measure the coercivity, saturation magnetization, and saturation field of these thin films. During the summer 2018 CSU Chemistry REU program, I designed and machined a sample holder for a new BLS experiment setup and used VSM to collect magnetic hysteresis loops for a series of magnetic thin films. The magnet and the sample holder I machined will soon be incorporated into the new BLS setup. The magnetic hysteresis measurements from the thin films provide important information on the film material properties, and they also give us advanced knowledge of the applied field strengths that are needed for the BLS measurements. |
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G01.00057: Hybrid Nanoscale Systems for Room Temperature Magnetocaloric Refrigeration Kellen Malone, George Smith, Logan Sutton, Meenakshi Singh Magnetocaloric materials vaulted into the forefront of alternative cooling technologies once they were proven to operate at room temperatures. These materials are preferred over vapor compression technology for their higher energy efficiency and reduced environmental impact. Even after numerous breakthroughs in magnetocaloric materials research though, there are still challenges to be resolved in order for these materials to out-compete current refrigerators in academic and commercial settings. Hybrid thin film systems are proposed and evaluated as solutions to these challenges, specifically a Nickel and Vanadium Dioxide (VO2) hybrid system. |
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G01.00058: A Different Mathematical Perspective " On The Ponderomotive Forces Exerted On Bodies At Rest In The Electromagnetic Field" by A.Einstein and J.Laub(1908) Mohammad Khoshnevisan A.Einstein and J.Laub(1908) have stated that forces vanish at infinity. In this brief note, it is shown shown that forces do not have to vanish only at infinity. Indeed, they are annihilated because R=-1/c∫Ωy(Sx+∂Ωy/∂z) df+(1/c∫ SxΩydf) which implies R=-1/c∫Ωy(∂Ωy/∂z)df- 1/c∫(SxΩydf)+1/c∫(SxΩydf)=-1/c(∫ ∂Ωy/∂z)df. Note that -Ωy∂Ωz/∂y has been transformed to -1/cΩy{Sx+∂Ωy/∂z}, and divβ=0 |
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G01.00059: Improving Automated Spectral Classifications Through Visual Inspections of Outliers Alexandra N. Higley, Brad W. Lyke, Danielle P. Schurhammer, Adam D. Myers One of the best ways to improve our knowledge of the physical cosmology of our universe is through observation of quasar spectra and redshift classification. My work includes visually inspecting Sloan Digital Sky Survey (SDSS) quasar spectra in order to improve cosmological parameters, improve the precision in clustering measurements for Baryon Acoustic Oscillations (BAOs) and improve automated computer pipelines. This is achieved by manually classifying the object, redshift, and any notable features in the quasar spectra we inspect, noting any peculiar cases that might contribute to revising automated spectral classifications and cosmology research. This presentation will provide the methods I have taken in visual inspection and classifications, outliers that we have found significant or intriguing, and examples of defining features that can aid the pursuits of cosmology. |
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