Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 57, Number 11
Friday–Saturday, October 26–27, 2012; Socorro, New Mexico
Session D1: Poster Session (3:00-4:30PM) |
Hide Abstracts |
Chair: Stipo Sentic, New Mexico Institute of Mining and Technology Room: Macey Center Lobbies |
|
D1.00001: Earth's field NMR; a surface moisture detector? Eiichi Fukushima, Stephen Altobelli, Andrew McDowell, Tongsheng Zhang Earth's field NMR (EFNMR), being free of magnets, would be an ideal teaching medium as well as a mobile NMR technique except for its weak S/N. The common EFNMR apparatus uses a powerful prepolarization field to enhance the spin magnetization before the experiment. We introduce a coil design geared to larger but manageable samples with sufficient sensitivity without prepolarization to move EFNMR closer to routine use and to provide an inexpensive teaching tool. Our coil consists of parallel wires spread out on a plywood to form a current sheet with the current return wires separated so they will not influence the main part of the coil assembly. The sensitive region is a relatively thin region parallel to the coil and close to it. A single turn of the coil is wound to be topologically equivalent to a figure-8. The two crossing segments in the center of a figure-8 form two of the parallel wires of the flat coil. Thus, a two-turn figure-8 has four crossing wires so its topologically equivalent coil will have four parallel wires with currents in phase. Together with the excellent sensitivity, this coil offers outstanding interference rejection because of the figure-8 geometry. An example of such a coil has 328 parallel wires covering a $\sim $1 meter square plywood which yields a good NMR signal from 26 liters of water spread out roughly over the area of the coil in less than one minute in a nearby park. [Preview Abstract] |
|
D1.00002: Software to Eliminate Algebraic Errors from Homework David Ludlow I will demonstrate a unique program which allows students to solve equations interactively by dragging the variables around the equation. The intended purpose is to help students eliminate algebraic errors from their homework and tests and boost students' workflow and attitude. I describe how the program is being incorporated into an algebra-based electromagnetism class. [Preview Abstract] |
|
D1.00003: Complex Time Propagation to Smooth the Quantum Leap John Russell, Paul Arendt, Jr. As is often noted, the propagator of quantum mechanics has much in common with the partition function of thermodynamics: $\exp(-it\hat{H})$ looks like $\exp(-\beta \hat{H})$, where $\beta$ is inverse temperature, when $t \to -i \beta$. It seems natural to combine these to form a ``complex time'' propagator, but this is commonly done only for fixed $\beta$, to include thermal effects. We instead allow $\beta$ to vary with time, and apply the propagator to the density matrix of a two-state system undergoing measurement. Zurek and others have developed decoherence and environment-induced superselection to allow the measurement process of quantum mechanics to behave quantum mechanically. However, there remains a quantum ``jump'' or ``leap'' of the state when an observer finally consults the measurement apparatus. Here, we adapt decoherence models into complex time propagation of the reduced system when the pointer basis is also the energy eigenbasis. Within a many-worlds or conditional probability interpretation, the evolution to the measured state is then smooth, preserves entanglement with the measuring apparatus, and gives meaning to the energy-time uncertainty relation. This may prove useful as a tool in qubit manipulation. [Preview Abstract] |
|
D1.00004: N-Photon Wave Packets Interacting with an Arbitrary Quantum System Ben Baragiola, Robert Cook, Agata Branczyk, Joshua Combes Traveling nonclassical states of light are important resources for quantum metrology, secure communication, and quantum networks. Motivated by this, we derive master equations for an arbitrary quantum system (e.g. a quantum harmonic oscillator or a multi-level atom) interacting with a wavepacket of light prepared in a multimode Fock state. We then generalize this to N-photon states with arbitrary spectral distribution functions and wavepackets in two polarization (or spatial) modes. Our method also allows the calculation of output field quantities. As an illustration of our formalism, we explore the strong coupling regime for an atom in free space and investigate the scattering of multimode Fock states from a two-level atom. [Preview Abstract] |
|
D1.00005: Macroscopic coherent rectification in Andreev interferometers Jonathan Meair, Philippe Jacquod We investigate nonlinear transport through quantum coherent metallic conductors contacted to superconducting components. We find that in certain geometries, the presence of superconductivity generates a large, finite-average rectification effect. Specializing to Andreev interferometers, we show that the direction and magnitude of rectification can be controlled by a magnetic flux tuning the superconducting phase difference at two contacts. The rectification current is macroscopic in that it scales with the linear conductance, and we find that it exceeds 5\% of the linear current at sub-gap biases of few tens of $\mu eV$'s. [Preview Abstract] |
|
D1.00006: The Optimal Cloner for Mixed States as a Quantum Operation John G. Gardiner, Jean-Francois S. Van Huele The no-cloning theorem in quantum information says that it is impossible to produce two copies of an arbitrary quantum state. This precludes the possibility of a perfect universal quantum cloner, a process that could copy any quantum state perfectly. It is possible, however, to find optimal approximations of such a cloner. Using the formalism of quantum operations we obtain the optimal quantum cloner for arbitrary mixed states of a given purity and find that it is equivalent to the Bu\v{z}ek-Hillery optimal cloner for pure states. We also find the fidelity of this cloner as a function of the chosen purity. [Preview Abstract] |
|
D1.00007: Lie algebras for time evolution with applications from chaos studies to spintronics Tim G. Wendler, Manuel Berrondo, Ty Beus, Ryan T. Sayer, Jean-Francois S. Van Huele We illustrate the power of Lie algebras in computing the time evolution of quantum systems with time-dependent physical parameters. By factorizing the quantum mechanical time evolution operator and using the linear independence of the Lie algebra generators, we reduce the operator equations to systems of coupled ordinary differential equations of scalar functions applicable to a variety of dynamical systems. We use the results to explore the possibility of detecting chaos in quantum nonlinear oscillators based on criteria from classical chaos studies and to follow spin currents in time-dependent spin-orbit coupled media. [Preview Abstract] |
|
D1.00008: Photoemission by Large Electron Wave Packets in a Relativistic Laser Focus Caleb Coburn, Eric Cunningham, Michael Ware, Justin Peatross We measure the radiation emitted from an electron whose wave packet has a size comparable to the wavelength of a driving laser. Such electrons are naturally produced during the ionization process in a high-intensity laser focus, where the sharp field gradients force portions of the wave packet over a large area. Using semi-classical quantum theory it is predicted that photoemission will be strongly suppressed as the wave packet size increases. However, fully quantized quantum theory predicts that radiation should be independent of the wave packet size. In this experimental work, we seek to confirm this fully quantized prediction by direct observation. We present our experimental design and noise floor results. [Preview Abstract] |
|
D1.00009: Determination of RGB Color Coordinates from Spectroscopic Reflectance Measurements Cesar Rodriguez, Cayla Nelson, Lina Abdallah, Stefan Zollner A numerical value (RGB coordinate) for a certain color, based on a color model, can be determined from a spectroscopic reflectance measurement. To obtain this measurement, an ellipsometer was used with a wavelength ranging from 380 nm to 780 nm to cover the visible light spectrum. The peaks seen in the reflectance versus wavelength graph represent the color of the sample used. Our paper samples were round and coated with a metallic paint. The data was then analyzed using ASTM Standard E308-99 (adopted in 1999) for ``computing the colors of objects by using the CIE system.'' Once a color is in the CIE color model, it can be transformed into an RGB color model and then compared to the RGB color displayed in many consumer electronics. [Preview Abstract] |
|
D1.00010: Investigating the Effects of Charge Asymmetry on the Early Structure of the Universe Cynthia Knight, Leanne Duffy, Bruce Carlsten The standard model of cosmology describes a charge neutral universe. It does not, however, completely rule out a small net charge. Currently, the best limit on this small charge is less than 10$^{-26}$e per baryon (where e is the charge of an electron) from the anisotropies of the Cosmic Microwave Background Radiation. We investigate the effect of a net charge on the early structure formation in the universe. A Friedmann-Roberston-Walker universe with uniform charge will have no observable electric or magnetic fields. Using a toy model of a spherical charge distribution, we demonstrate that charge in the universe can have interesting effects. We discuss our approach to investigating the effects of charge on structure formation, using linear cosmological perturbation theory. This work, paired with observation, will give new information on charge in the universe. [Preview Abstract] |
|
D1.00011: Modeling Spiral Galaxy Luminosity Profiles Jordan Rozum, Shane Larson, Matt Garlock, Bradley Carroll The distribution of spiral and bar galaxy inclination angles is expected to be uniform. However, analysis of several major galaxy catalogs shows this is not the case; galaxies oriented near edge-on are significantly more common in these catalogs. In an attempt to explain this discrepancy, we have developed a galaxy simulation code to compute the appearance of a spiral type galaxy as a function of its morphological parameters. We examine the dependence of observed brightness upon inclination angle by using smooth luminous mass density and interstellar medium (ISM) density distributions. The luminous mass component is integrated along a particular line of sight, thus producing a mass distribution, from which a surface luminosity profile is derived. The ISM component is integrated alongside the luminous mass component to account for light extinction. If the dependence of the total surface brightness on inclination strongly corresponds to the observed distribution of inclination angles, we can attribute much of the discrepancy to a geometrical selection effect. [Preview Abstract] |
|
D1.00012: Resolving the Chemistry of Molecular Gas that Fuels Luminous Starburst Galaxies David Meier, Jean Turner, Crystal Anderson Energy input from massive stars profoundly impact on how starburst galaxies evolve. Both the triggers of and feedback from star formation manifest themselves in the gas chemistry. We use millimeter interferometry to obtain high spatial resolution maps of CO, HCO$^{+}$, CCH, NNH$^{+}$, HNCO, CH$_{3}$OH and SiO, toward the starbursts, Maffei 2, M 82, IRAS 04296+2923 and Arp 220. Dramatic variations in gas chemistry are observed both within the individual galaxies and from galaxy to galaxy. These variations correlate with star formation and gas dynamics. CO isotopologues are used to constrain the evolutionary history of star formation. Species preferentially formed (CCH) and destroyed (NNH$^{+}$) in the presence of strong UV radiation map out where energy input from the massive stars dominate. CCH abundances are correlated with star formation rate, except in the most extreme starburst, Arp 220, whereas NNH$^{+}$ abundances drop, except for Arp 220. The abundance anomalies in Arp 220 hint that the molecular medium in the most extreme starbursts is different. HNCO, CH$_{3}$OH and SiO locate shocks due to bars and galaxy-galaxy mergers in these systems. Comparisons between these species suggest shock strength does not change across bars, but does for merger remnants. [Preview Abstract] |
|
D1.00013: Physical and Chemical Conditions in Centaurus A Mark McCoy, Juergen Ott, David Meier We present high-resolution maps of rotational transitions of the molecules $^{12}$C$^{16}$O, $^{13}$C$^{16}$O, $^{12}$C$^{18}$O, HCN, and HCO$^{+}$ toward the nuclear region of the nearby active galaxy, Centaurus A (Cen A). At $\sim $3.8 Mpc away, Cen A is the closest radio galaxy, so it serves as the best laboratory for determining how accretion onto a supermassive black hole affects the structure and evolution of a galaxy. The data were obtained with the Atacama Large Millimeter Array interferometer during Early Science commissioning. The CO isotopologue data reveals the morphology of Cen A. Two arm-like features were found along with a $\sim $200 pc disk-like feature associated with the supermassive black hole. The CO isotopologues preferentially trace the arms, while HCN and HCO$^{+}$, tracers of high density gas, dominate the disk feature. Large velocity gradient radiative transfer models of the CO line ratios constrain the gas in the arms to be warm (T$>$50 K) and modestly dense (n$_{H2}\sim $10$^{3}$ cm$^{-3})$. The enhanced emission from HCN and HCO$^{+}$, suggest the disk-like feature is much denser, or influenced by anomalous chemical processes from the black hole radiation field. [Preview Abstract] |
|
D1.00014: Light Curves of Supernovae Michelle Spencer, Michael Joner, David Laney, Emily Stoker Photometric Data were secured for the supernovae 2010hh, 2011dh, 2011fe and 2012aw before the dates which each individual maxima occur. The data for all supernovae were secured using the 0.9-meter telescope at the BYU West Mountain Observatory in Utah. 2010hh data were secured during the summer 2010 over the months of August to October. 2011dh and 2011fe data were secured during the summer of 2011. 2012aw data were secured during the summer of 2012. The data exposures from 2010 were secured using standard B,V and R filters. The frames for 2011 were secured using B,V, R and I filters. The 2012 supernova frames were secured in B,V and R filters. Using the data I will compare and contrast these four different supernovae and discuss their possible uses for distance determinations for the host galaxies. [Preview Abstract] |
|
D1.00015: Polarimetry of the Massive Eclipsing Binary Star V356 Sagittarri Mike Malatesta, Jennifer Hoffman, Jamie Lomax A supernova is the explosion of a massive star. Some supernovae are characterized by unique, non-spherical, ionized gas clouds that were expelled by the progenitor star before it exploded. In a binary system the process of forming the gas clouds and the supernova becomes more complex. In these binary systems, matter can be transferred from one star to another, creating a mass stream and a disk-like gas cloud surrounding the receiving star. Because most stars occur in binary systems, it is important that we understand the effects of this mass transfer on the subsequent stellar ejection and explosions. Using a process called polarimetry, I study the effects that circumstellar material has on passing light. Through polarimetry we can determine the chemical make-up of gas clouds, describe their shapes and densities, and detect other features such as jets that may affect the behavior of the eventual supernova. I have compiled four years of data on the massive eclipsing binary star V356 Sagittarii, which is a likely supernova progenitor. The polarimetric variations we observe as the stars orbit each other yield detailed information about the circumstellar environment of the two stars and allow us to predict the properties of the future supernova explosion. [Preview Abstract] |
|
D1.00016: AKARI MLHES Data Set Processing with FAST Rachael Tomasino, Toshiya Ueta, Issei Yamamura The AKARI MLHES (excavating Mass Loss History in Extended dust shells of Evolved Stars) data set is the largest collection of the most sensitive far-infrared images of the cold extended circumstellar dust shells of evolved stars and it is the key to understanding the dusty mass loss phase of stellar evolution. This data will be processed with a new imaging tool kit FAST (FIS-AKARI Slow-scan Tools). This program allows for an interactive assessment of the data quality and on-the-fly corrections to the time-series data on pixel-by-pixel bases in order to manually correct glitches that would have been missed in the automated process. These corrections include: eliminate bad on-sky calibration sequences, flag out cosmic-rays and their after-effect affected time-series readings from the data stream and remove real sources from local sky-flat frames, among other options. These extra processes result in better-calibrated noise reduced images and would be by far the best detection limit among all existing far-infrared data of extended evolved star dust-shells. Suggestions to improve to the GUI interface and problems with the data visualization were recorded and plan to be implemented in subsequent versions. [Preview Abstract] |
|
D1.00017: From Gas to Stars in Energetic Environments: Dense Gas Clumps in the 30 Doradus Region Crystal Anderson, David S. Meier, Juergen Ott, Annie Hughes, Tony Wong We present interferometric mapping of dense molecular gas tracers toward the giant molecular clouds (GMCs) of the star forming region 30Dor10, located in the Large Magellanic Cloud (LMC) conducted with the Australia Telescope Compact Array (ATCA). The LMC is the nearest major galaxy to the Milky Way and it contains the most intense star forming region in the Local Group. The large number of OB stars in 30 Doradus create a very intense ionizing photon field, that in combination with the sub-solar metallicity of the LMC, may mimic the conditions present in young starburst galaxies of the early Universe. HCN(1-0) and HCO$^{+}$(1-0) transitions, tracers for dense, ultimately star forming molecular clumps are mapped at parsec scale resolution. We show the first detection of several resolved clumps in 30Dor10, with some of these clumps possibly tracing a molecular filament. We present detailed comparisons of clump structure (masses, linewidths, sizes) in 30Dor10 to those in other star forming regions of the LMC. These observations also reveal low HCN/HCO$^{+}$line ratios in 30Dor10 compared to some of the other LMC GMCs. [Preview Abstract] |
|
D1.00018: Studies in Stellar Spectroscopy using the Sommers-Bausch Observatory 24" Telescope David Simmons, Brandon Bell, Raymon Furth, Guy Stringfellow Sommers-Bausch Observatory (SBO) was founded in 1953 and is located near downtown Boulder on the University of Colorado campus. In recent years, the telescope has been used largely as an undergraduate teaching facility. During the summer of 2012, we set out to investigate the current scientific capabilities of SBO by taking part in an international campaign monitoring the variable stars HD 168607 \&\/ HD 168625. The monitoring campaign, led by Dr. Stringfellow, involved six space and ground-based telescopes taking a combination of spectra and photometry. We also obtained spectra of a nova (Sgr. 2012 No.4) and a symbiotic star. The quality of these spectra indicate that the SBO 24" can still be used to contribute important scientific results to various topics in stellar spectroscopy, particularly regarding variable stars. Spectra of emission line stars can be obtained down to a limiting magnitude of V$\sim$11 covering a wavelength range of 4705\AA-6820\AA\/ with a resolving power of R$\sim$3600. We will continue to use the SBO 24" to spectrally monitor novae, symbiotic stars, LBVs, and other variable stars. [Preview Abstract] |
|
D1.00019: Searching for M Dwarf Flares in Raptor-Q All-sky Photometric Data Tristan Wolfe, P.R. Wozniak, Tom Vestrand Stellar flares are releases of magnetic energy that cause emissions of a wide range across the electromagnetic spectrum. Flares of M dwarf stars are characterized by a large increase in blue and near-UV emissions, causing an increase in several magnitudes within minutes (Hilton et al, AJ, 2010). Exoplanets of several Earth masses have been discovered orbiting M dwarfs, so the search for M dwarf flares is very important, as the planets' atmospheres and habitability may be affected by these bursts in energy. Using data from Los Alamos National Labs' Raptor-Q telescope at Fenton Hill, NM, we are developing an automated method of detecting M dwarf flares. Raptor-Q operates robotically and, with five cameras, collects over 10,000 images of 90\% of the sky above 12 degrees elevation in a given night, with a sensitivity up to magnitude R=10 (Wren et al, Proc SPIE, 2010), and automatically provides photometric and astrometric reductions of its images. A prototype pipeline has been developed using Python that looks for transient light curves (quick changes in magnitude over time) in Raptor-Q's data. These light curves will then be analyzed for characteristics of stellar flares, and cross-correlated with published catalogs to determine stellar type and any previous observations of flares. [Preview Abstract] |
|
D1.00020: Characterizing Sky Variability for Multi-Messenger Astronomy Rachel Nydegger, Shane L. Larson Multi-messenger astronomy employs both electromagnetic and gravitational -wave detectors to paint a richer picture of celestial objects, providing more depth and information. The interferometers utilized for gravitational-wave observations receive input from very broad fields of view on the sky, typically a few square degrees. To have simultaneous electromagnetic observations (typically less than one square degree) requires innovative techniques for the telescopes to find the origin of radiation. One idea is to ``tile'' the view of the interferometer, using multiple telescopes to simultaneously point at different areas of the field to observe the source. One problematic aspect of this observing paradigm is distinguishing random electromagnetic variable sources from a gravitational-wave counterpart. To better understand this problem, this project repeatedly observes a single field on the sky. Each observation is analyzed to count the number of sources that appear in the field as a function of brightness. Repeating this process over time will yield the frequency of random optical transients, as well as characterize the population and brightness distribution of variables in the field. Future work will extend this observation campaign to cover different galactic latitudes. [Preview Abstract] |
|
D1.00021: Closing the loop on MROI Tyler McCracken, Alisa Shtromberg, Michelle Creech-Eakman, John Young, David Buscher, Chris Haniff To produce a high quality science product, optical and near infrared interferometers must battle the shakes, bumps, and rattles of the environment while correcting for the constantly changing atmosphere. The planned Magdalena Ridge Observatory Interferometer (MROI) will have baselines up to 347 meters requiring beam transport of the same scale. Thus alignment of the beam transport system is crucial and can pose a significant reduction in time available for observations due to both the standard beginning of night alignment and how misalignments arising overnight are detected and corrected. For high contrast fringes to be continuously observed, the turbulent atmosphere must also be tracked and its effects minimized. This poster overviews some subsystems of the MROI responsible for minimizing the effort needed for alignment and correcting atmospheric effects with focus on the laboratory demonstration of the systems. [Preview Abstract] |
|
D1.00022: Ground-based Characterization of Exoplanet Atmospheres H. Bloemhard Of the many confirmed exoplanets, we know the detailed chemical composition and temperature structure of only a handful. Transiting exoplanets present us with the interesting opportunity to characterize their atmospheres. Until 2009, only space-based platforms had been successful at this type of characterization. Since then, ground-based spectroscopy has made significant contributions to exoplanet characterization. The IRTF/SpeX instrument combination has been used to reliably reproduce space-based results while obtaining new and unexpected information. Our team has been applying lessons learned at IRTF/SpeX to the design of a new ground-based spectrometer, the New Mexico Tech Exoplanet Spectroscopic Survey Instrument (NESSI). NESSI, a collaborative effort between researchers at NMT, MRO, and NASA JPL, is purpose built to characterize exoplanet atmospheres. In anticipation of first light in a few months, I will present an update on NESSI progress, including a summary of NESSI's unique features. [Preview Abstract] |
|
D1.00023: Observations of Oscillatory Behavior in the Corona Brandon Calabro, R.T. James McAteer, Shaun Bloomfield The solar corona is millions of degrees hotter than that of the surface of the Sun and we do not know why. We attempt to resolve this long standing coronal heating problem by looking at how waves transport energy to the corona. In each region studied the 3-minute periodicity is more frequent than the 5- minute periodicity. The number of pixels exhibiting the 3- minute periodicity is between 10\% - 20\% and those pixels exhibiting 5- minute periodicity is between 3\% - 7\% of the total number of pixels observed. Our results show 3- minute oscillations along coronal loop structures but do not show 5- minute oscillations along these same loop structures. The variation in the number of pixels exhibit- ing 3- and 5- minute periodicity is roughly the same across all regions observed leading us to infer that the 3- and 5- minute oscillation is the result of a global mechanism. [Preview Abstract] |
|
D1.00024: X-Flare Analysis of Solar Cycle 23 Using Solar and Heliospheric Observatory (SoHO) Data Fernando Delgado, Aleksandra Andic, R.T. James McAteer We identify trends and patterns that may be used in automated flare detection algorithms with real-time data from the Solar Dynamics Observatory (SDO). We analyzed the magnetic field intensities and areal dimensions of active regions that produced the 30 strongest X-class flares during solar cycle 23 (1996-2007). The data were obtained through SoHO's Michelson Doppler Imager (MDI). The magnetograms underwent thresholds to identify positive and negative polarities, 1000 and -1000 Gauss respectively. Each active region was observed several days before and up to a few hours after the flare occurred. Based on preliminary results, about one third of the flares show a similar linear growth pattern in which the flare occurs near or at the peak of growth. [Preview Abstract] |
|
D1.00025: RHESSI Results Analyzed in Seasonal Quadrants Carolynn Conley, Samina Masood The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) Small Explorer Mission was launched on Feb. 5, 2002. For over a decade, in addition to collecting the intended solar flare and coronal mass ejection data, RHESSI has also observed lightening generated energetic eruptive events. These Terrestrial Gamma rays Flashes (TGFs) have been observed since 2002. TGFs have an apparent random spread in occurrences of the latitudes and longitudes observed. We investigate the seasonal variation in the RHESSI data. The TGFs since the start of 2002 to 2012 suggest that a distribution of activity may be observed. We compare the TGF weekly rates at the four seasons, spring, summer, fall, and winter, in the northern and southern hemispheres. The data suggests that the TGF rate varies according to the relative position of the earth to the sun and the earth's geographic and magnetic poles. [Preview Abstract] |
|
D1.00026: Nucleosynthesis of the elements and the liquid metallic hydrogen model of the Sun Pierre-Marie Robitaille Modern nucleosynthesis theory stems from the anticipated life cycle of stellar objects. Within this framework, the Sun, as a relatively young and light main sequence star, is unable to synthesize any element beyond helium. All metallic elements in our solar system have consequently been hypothesized to arise from the explosion of early stars which previously populated this region of the galaxy. Much of nucleosynthesis theory currently rests on gaseous stellar models and has developed in a direction consistent which such objects. In this presentation, the problem of nucleosynthesis is briefly reconsidered within the context of a condensed Sun. Such an object, built from liquid metallic hydrogen provides a new avenue for nucleosynthesis. Nuclei and protons contained within a metallic hydrogen lattice, will be subjected to vibrational modes which should be conducive to promoting internuclear reaction. The pressures within the Sun should make the synthesis of all the elements possible based on the combination of lighter elements. In stark contrast to current theory, it is advanced that all elements, beyond hydrogen, can be made within such a thermonuclear furnace. [Preview Abstract] |
|
D1.00027: Simulations of the Jovian Stratosphere with diabatic heating and mechanical forcing Richard Cosentino, Raul Morales-Juberias The coupling of dynamical and chemical processes in the middle atmosphere of Jupiter determines the structure of mean temperatures and mean zonal winds. The Cassini flyby of Jupiter in December 2000 provided detailed information about the mean temperatures and atmospheric abundances of methane, acetylene and ethane in the Jovian atmosphere. We incorporate a two dimensional net heating rate derived from these hydrocarbons into a general circulation model (GCM) to explore the impact on the evolution of stratospheric temperatures. This thermal forcing alone does not produce agreement between the observations and model outputs, so we also investigate mechanical forcing by waves. Atmospheric waves are known to directly impact the upper troposphere and lower stratospheres of Earth and Jupiter. Since there is not enough observational evidence to completely characterize the source spectrum in Jupiter, we implement a gravity wave drag parameterization in the GCM following Friedson (1999). This consists of a flat source spectrum of waves and dissipation mechanism like that by Lindzen and Holton (1968). We present the results obtained by using both a heating forcing derived from remote sensing observations and a mechanical forcing by waves on the Jovian stratosphere. [Preview Abstract] |
|
D1.00028: Short period gravity waves in the Arctic atmosphere over Alaska Michael Negale, Kim Nielsen, Mike Taylor, Brita Irving, Richard Collins The propagation nature and sources of short-period gravity waves have been studied extensively at low and mid-latitudes, while their extent and nature at the polar regions are less known. During the last decade, observations from select sites on the Antarctic continent have revealed a significant presence of these waves over the southern Polar Region as well as shown unexpected dynamical behavior. In contrast, observations over the Arctic region are few and the dynamical behavior is unknown. A recent project was initiated in January 2011 to investigate the presence and dynamics of these waves over interior Alaska. This site provides an exceptional opportunity to establish a long-term climatology of short-period gravity waves in the Arctic, including their dominant source regions, influences of large-scale tidal and planetary wave motion, as well as impact of dominant weather systems such as the polar vortex and Aleutian low. Here we present initial measurements of short-period gravity waves in the Arctic atmosphere over Alaska. [Preview Abstract] |
|
D1.00029: Polar Vortex and Temperature Diagnostics for Intercomparisons and MLS Data Inspection: Update on Antarctic 2012 Meteorology in Relation to MLS Data Zachary Lawrence, Gloria Manney, Ken Minschwaner Stratospheric temperature diagnostics are important indicators for evaluating the severity of polar winters and the susceptibility to conditions that lead to ozone loss at the poles. The availability of many meteorological datasets with temperature products that span multiple years allows for direct comparisons between satellite measurements (the Aura Microwave Limb Sounder, MLS), operational data assimilation systems, and reanalysis data sets produced by meteorological forecast centers. We focus on two diagnostics: first, the area where temperatures are less than the threshold temperatures for the formation of Polar Stratospheric Clouds (PSCs), and second, the minimum daily temperatures over the course of the polar winters. Both diagnostics have a long history of use for monitoring the wintertime polar stratosphere, and we will present a comparison of results based on updated data products and analysis techniques, along with an update on meteorological conditions and ozone for the 2012 Antarctic winter. [Preview Abstract] |
|
D1.00030: Large Eddy Simulations of Springtime Arctic Mixed-Phase Clouds Erika Roesler, Derek Posselt Observations and modeling results have shown the high latitudes' environment changing in a warmer climate. The research presented here focuses on understanding diifferences in the parameterizations made to simulate the Arctic mixed-phase stratocumulus (AMPS) clouds and the sensitivity of the AMPS to changing environmental conditions. The level of complexity needed to simulate this cloud is investigated with two microphysics routines and two subgrid scale turbulent closure models. It was found the both microphysics accurately produced macrophysical properties of the observed cloud, and that the less computationally expensive microphysics parameterization could be used to reproduce the AMPS. When the subgrid scale turbulent closure models were evaluated with the microphysics routines, it was found the choice of turbulent closure model had more of an effect on the cloud properties than the choice of microphysics. Knowledge of the parameterizations needed for representing the AMPS were applied to a paramter-space-filling uncertainty quantification technique in DAKOTA to understand the sensitivity of the AMPS to changes in its environment. It was found from the environmental sensitivity study that the AMPS did not form unconditionally, and that environmental thresholds exist. [Preview Abstract] |
|
D1.00031: Modeling Observations from EPIC 2001 in the Weak Temperature Gradient Approximation Andrew Arrasmith, Sharon Sessions The Weak Temperature Gradient (WTG) is a parameterization for convection by the large scale environment used for modeling convection in the tropics. We use WTG simulations to study the extent to which tropical convection is driven by different factors by comparing these simulations to observations. Specifically, we compare the output of these simulations to data taken during the EPIC (Eastern Pacific Investigations of Climate) 2001 field campaign. The data from the EPIC program are used to generate time dependent perturbations on the reference profile used by the simulation for the ambient thermodynamic conditions as well as the local surface wind speeds. We compare four simulations: one with no perturbations, one with thermodynamic perturbations, one with wind speed perturbations, and one with all of the perturbations. Here we report on the results by comparing the evolution of dynamical quantities from the simulations to the evolution of the same in the EPIC data. [Preview Abstract] |
|
D1.00032: The Diurnal Cycle of Precipitation Over Tropical Oceans and the Weak Temperature Gradient Approximation Leah Lindsey, Sharon Sessions Convection and circulation processes in the tropics have a significant impact on global climate. Understanding the mechanisms that force convection in the tropics will help to improve global circulation models. An important process that is still not fully understood is the diurnal rainfall variability. Here, we use the weak temperature gradient (WTG) approximation to determine the extent to which diurnal variability in precipitation is controlled by the thermodynamic environment. The basis for the WTG approximation is that the virtual temperature is nearly horizontally uniform and thus has a constant vertical profile in the tropics. Any change in the vertical temperature profile as a result of surface fluxes, latent heat release, or radiation is counteracted by gravity waves. In the model, a vertical velocity is generated to counteract diabatic heating. Using a cloud resolving model, we impose observed diurnal variations in the reference profiles of potential temperature and moisture. The perturbations are taken from the EPIC field program (East Pacific Investigation of Climate Processes in the Coupled Ocean-Atmosphere System, September -- October 2001), and the reference profiles represent the convective environment. We compare simulated diurnal cycles in precipitation to observations and find good agreement in timing of precipitation maximum. This suggests that thermodynamic control of diurnal rainfall is important. [Preview Abstract] |
|
D1.00033: Self-Organized Criticality, phase transition, and the moisture and rain rate in the tropics Satomi Sugaya, Joseph Galewsky, Sharon Sessions Self-Organized Criticality (SOC) has been proposed as a potential framework to describe the relationship between the moisture and rain rate in the tropics (Peters and Neelin 2006). The authors claimed that the relationship can be seen as a second order phase transition happening in nature. Hence the system was said to self-organize towards the critical phase transition. However, this view is an issue of debate (see Bretherton et al. 2004; Muller et al. 2009). Although SOC lacks a clear definition (Jensen 1998), it has come to known as a phenomenon that describes a certain set of dissipative dynamical systems which have two phases, stable and dissipative. The dissipative phase onsets when the threshold for stored energy of the stable phase is surpassed. The dissipative phase works to relax this excess energy and restores the system to its stable configuration. The interplay between the dissipative and the stable phases of a system produces a power-law distribution in the magnitude of the dissipative events. From this perspective, SOC does not involve a phase transition as observed in equilibrium systems. Therefore, although the suggested evidence for the SOC theory for tropical moisture dynamics may well qualify for second order phase transition, they do not qualify for SOC phenomenon. [Preview Abstract] |
|
D1.00034: Examining Stratocumulus Properties over the Southeast Pacific Isabel McCoy, Andreas Muhlbauer, Robert Wood Variability in Stratocumulus (Sc) clouds is important to the planetary albedo and radiation budget because they reflect incoming shortwave radiation back to space thereby cooling the atmosphere. Understanding more of their micro and macro physical properties is essential to reduce uncertainty in global climate model prediction and add confidence in future climate predictions. In 2006, Robert Wood and Dennis Hartmann characterized Sc clouds into four main categories based on their morphology and level of mesoscale organization. In this poster, we focus on two of these categories, namely open and closed cells, because of their differing cloud coverage. We use satellite data (from NASA's CloudSat and Goes 10) in combination with the occurrence identifications to develop statistics on the microphysical characteristics for each type of cloud. The results compare successfully to the aircraft data from a recent campaign sampling the same region (the VOCALS Regional Experiment over the Southeast Pacific for Oct. and Nov. of 2008). We find that, when the two cases are contrasted, the open cells have both a higher drizzle rate (at cloud base) and a larger range of rates than the closed. Further, this method of characterizing satellite data to derive pertinent results about Sc clouds is successful. Whether these properties are specific to the Southeast Pacific Sc clouds, and if similar results can be found for expanded time and area, is the topic of future research. [Preview Abstract] |
|
D1.00035: Visualizing Air Around a Splashing Drop Kelly W. Mauser, Irmgard Bischofberger, Sidney R. Nagel It is well known that when a drop impacts a surface at a large enough velocity it will splash. ~However, it was recently discovered that removing the surrounding air from a drop can suppress splashing completely. ~This discovery still remains unexplained. ~Not only is it not understood why the air matters but it is also not even known where the liquid-air interaction is important: ~Is it beneath the drop, is it at the drop's edge or is it at the drops upper surface? ~~Using modified schlieren optics combined with high-speed video imaging, we were able to visualize vortices in the air~that were created when the drop~spread out rapidly after~hitting the substrate. ~~These vortices~varied with impact velocity and splash type. ~We are currently measuring the strength of forces created by the air on the upper surface of the drop in order to confirm our tentative conclusion that~it is the air above the spreading drop that plays the dominant role in creating a splash. [Preview Abstract] |
|
D1.00036: Single{\_}Shot Diffraction Limited Fourier Holography Scheme using a Table top Soft X-ray Laser Erik Malm, Nils Monserud, Chris Brown, Przemyslaw Wachulak, Ganesh Balakrishnan, Mario Marconi Single-shot Fourier transform holography has been demonstrated utilizing a 46.9~nm table-top plasma discharge laser. A zone plate illuminated by the laser light is used to form both the reference wave and the object waves. The object waves are formed from plane waves scattering off a non-transparent object. The interference pattern between the spherical reference wave and the object waves is recorded on a charge-coupled device. The resolution limit of 150~nm is determined by the focal spot size of the zone plate. A knife-edge scan of the resulting hologram obtains a single-shot spatial resolution of 163~nm. This setup has been designed for analyzing nano-pillar dynamics for the purpose of single-molecule mass detection. The nonlinear coupling between pillars allows for a higher sensitivity than single pillar detection schemes. [Preview Abstract] |
|
D1.00037: Infrared Lattice Dynamics of LaAlO3 Travis Willett-Gies, Eric Delong, Stefan Zollner, Lina Abdallah, Igal Brener Lanthanum aluminate (LaAlO$_3$) is a member of the group of ceramics known as perovskites which have many potential applications in the semiconductor industry. Lattice vibration energies of LaAlO$_3$ were determined using infrared ellipsometry. Scans were taken from 200 to 5000 cm$^{-1}$ in air at 300 K. The data was used to calculate the complex dielectric function of LaAlO$_3$ from which the energies and intensities of the long wavelength infrared-active lattice vibrations could be determined. An intense phonon mode with $\omega$=426.97$\pm$0.07 cm$^{-1}$ and $\Gamma$=4.05$\pm$0.11 cm$^{-1}$ as well as a secondary absorption peak with $\omega$=652.93$\pm$0.06 cm$^{-1}$ and $\Gamma$=21.42$\pm$0.18 cm$^{-1}$ were found. These results agree with phonon energies found in previous reflectance experiments. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Los Alamos National Laboratory (Contract DE-AC52-06NA25396) and Sandia National Laboratories (Contract DE-AC04-94AL85000). [Preview Abstract] |
|
D1.00038: Composition Dependence of the Optical Conductivity of NiPt Alloys Determined by Spectroscopic Ellipsometry Lina Abdallah, Tarek Tawalbeh, Igor Vasiliev, Stefan Zollner, Christian Lavoie, Ahmet Ozcan, Mark Raymond The complex dielectric function of different Ni-Pt alloys (0{\%} to 25{\%} Pt concentration, 10nm thickness) was determined using spectroscopic ellipsometry over a broad photon energy range from 0.6 to 6.6eV. Data were fitted using basis spline functions as well as Drude-Lorentz oscillators to describe free carrier absorption and interband transitions. We found absorption peaks at 1.5 and 4.7 eV due to interband transitions. Results showed a broadening in the absorption peak of Nickel with increasing the Platinum concentration in the alloy. The experimental results were compared with ab initio density functional theory band structure calculations which showed that adding Platinum enhances the density of states of Nickel especially at low energies. Annealing the metals at 500$^{\circ}$ C for 30 s increases the optical conductivity. [Preview Abstract] |
|
D1.00039: Photoexcitations of sexithiophene for use in all organic spin vlaves Cayla Nelson, Megan Harberts, Athur Epstein Spintronics is an emerging field in solid state devices that takes advantage of the angular spin momentum of the electron to transport and store information. Current spintronic technology is used in magnetic memory and sensor devices. Replacing metals with semiconductors in spintronic devices could provide new methods for electronic logic. Further, organic semiconductor materials are attractive due to their lightweight, long spin lifetime, mechanical flexibility, and low cost. Presently, we are reaching the limit of capabilities for modern electronics; spintronics shows the possibility for faster and smaller devices. One device used to detect spin injection is a spin valve, which sandwiches a non-magnetic conducting material between two different ferromagnetic conductors. The organic semiconductor, sexithiophene, is a candidate for the non-magnetic layer in a spin valve. Polaron and bipolaron defects, in the molecular chain of sexithiophene allow for conduction in the material. These defects sit at energies located within the bandgap, and can be created through photoexcitation. For this work sexithiophene thin films were measured using a spectrophotometer to obtain a linear absorption spectra. The project will continue by measuring the photoinduced absorption spectra of sexithiophene to locate the energy of the defects. Photoexcitation of the nonmagnetic conducting organic layer in a spin valve will allow for a multifunctional device. [Preview Abstract] |
|
D1.00040: Electrostatic Discharge Properties of Fused Silica Coatings Allen Andersen, Charles Sim, J.R. Dennison The electric field value at which electrostatic discharge (ESD) occurs was studied for thin coatings of fused silica (highly disordered SiO2/SiOx) on conductive substrates, such as those encountered as optical coatings and in Si microfabrication. The electrostatic breakdown field was determined using an increasing voltage, while monitoring the leakage current. A simple parallel-plate capacitor geometry was used, under medium vacuum and at temperatures down to $\sim $150 K using a liquid N2 reservoir. The breakdown field, pre-breakdown arcing and I-V curves for fused silica samples are compared for $\sim $60 nm and $\sim $80 $\mu $m thick, room and low temperature, and untreated and irradiated samples. Unlike typical I-V results for polymeric insulators, the thin film silica samples did not exhibit pre-breakdown arcing, displayed transitional resistivity after initial breakdown, and in many cases showed evidence of a second discontinuity in the I-V curves. This diversity of observed discharge phenomena is discussed in terms of breakdown modes and defect generation on a microscopic scale. [Preview Abstract] |
|
D1.00041: Neutron scattering studies of solid state lithium electrolyte materials Leo Zella Lithium electrolyte material research will dramatically impact the future of lithium-ion battery technology. We have investigated lithium electrolyte materials toward improving energy transfer rates in batteries. It has been shown by others that differences in conductivity are observed when materials have been heated. Our hypothesis is that the creation of crystalline subunits within our sample B occur during heating which decreases conductivity. To test this, we used neutron powder diffraction and triple axis spectroscopy to characterize these materials before and after heating. Increased crystallization was observed as inferred from the growth of specific Bragg diffraction peaks during the heating cycle from room temperature to 450K. In-situ diffraction measurements made during the heating cycle, also suggest solid state chemistry takes place that alters the material properties. This suggests that a thermal phase change occurs during heating. The triple axis spectroscopic data analysis of our unheated sample C provides information about energy transfer. From these measurements we can obtain information regarding the nature of the dynamic processes from the observed diffuse scattering in the materials. [Preview Abstract] |
|
D1.00042: Neutron Detection Research at BYU Nirdosh Chapagain, Alexander M. Corey, J. Bart Czirr, Brian James, Trevor M. Jex, Matthew S. McArthur, Lawrence B. Rees Neutron detectors are used in national security applications to detect potential radioactive materials. Since there is a shortage of Helium-3, a typical neutron detection material, BYU and associates have been pursuing technologies that may serve as an alternative to Helium-3 detectors. US Homeland Security requires that a replacement for Helium-3 detectors must have low gamma sensitivity and high neutron detection efficiency. Different techniques of neutron-gamma discrimination have be developed and tested at BYU. Presented will be an overview of Cadmium capture-gated neutron detection and Lithium-6 broken glass modulation techniques. [Preview Abstract] |
|
D1.00043: Comparing Theory and Experiment for Analyte Transport in the First Vacuum Stage of the ICP-MS Matthew Zachreson, Ross Spencer The Direct Simulation Monte Carlo algorithm as coded in FENIX has been used to model the transport of trace ions in the first vacuum stage of the inductively coupled plasma mass spectrometer. Haibin Ma collected two radial trace density profiles: one .5 mm upstream of the sampling cone and the other 10 mm downstream. We will compare the simulation results from FENIX with the experimental results. To better understand the simulation results, two fluid codes have been written. One uses ideal convection and the other uses both convection and diffusion. This enables us to compare convection, convection and diffusion, three body recombination, and full long-mean-free-path simulation with each other and with the experimental data in order to see the importance of each of these effects. Discharge quenching in the region upstream of the sampler has a significant effect on the trace density profile. This and other results will be presented. [Preview Abstract] |
|
D1.00044: Neoclassical study of temperature anisotropy in NSTX experiments using the GTC-NEO particle code David Perkins, Stephane Ethier, Weixing Wang Ion thermal transport in the National Spherical Torus eXperiment (NSTX) is often observed to be close to the neoclassical level. This makes self-consistent neoclassical simulations carried out with the GTC-NEO particle code highly relevant for studying transport-related issues in NSTX. GTC-NEO, which now treats multiple species of ion impurities[1], takes as input the experimental profiles from NSTX discharges and calculates fully non-local, self-consistent neoclassical fluxes and radial electric field. Given that the fraction of trapped particles is high in spherical tokamaks, one remarkable question is that of possible temperature anisotropy, which cannot be determined experimentally with the current diagnostics. Some experimental measurements assume the temperature anisotropy for the interpolation of raw data from diagnostics. This work describes new numerical diagnostics and computational improvements that were implemented in GTC-NEO to enable the study of temperature anisotropy. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700