Study Of Morphological Changes In Mgh2 Destabilized Libh4 Systems Using Computed X-Ray Microtomography,
2012
Rowan University
Study Of Morphological Changes In Mgh2 Destabilized Libh4 Systems Using Computed X-Ray Microtomography, Tabbetha A. Dobbins, Shathabish Narasegowda, Leslie G. Butler
Faculty Scholarship for the College of Science & Mathematics
The objective of this study was to apply three-dimensional x-ray microtomographic imaging to understanding morphologies in the diphasic destabilized hydride system: MgH2 and LiBH4. Each of the single phase hydrides as well as two-phase mixtures at LiBH4:MgH2 ratios of 1:3, 1:1, and 2:1 were prepared by high energy ball milling for 5 minutes (with and without 4 mol % TiCl3 catalyst additions). Samples were imaged using computed microtomography in order to (i) establish measurement conditions leading to maximum absorption contrast between the two phases and (ii) determine interfacial volume. The optimal energy for measurement was determined to be 15 keV …
Degenerate Parallel Conducting Layer And Conductivity Type Conversion Observed From P-Ge1 - YSnY (Y = 0.06%) Grown On N-Si Substrate,
2012
Kangwon National University
Degenerate Parallel Conducting Layer And Conductivity Type Conversion Observed From P-Ge1 - YSnY (Y = 0.06%) Grown On N-Si Substrate, Mee-Yi Ryu, Yung Kee Yeo, M. Ahoujja, Thomas R. Harris, Richard T. Beeler, John Kouvetakis
Faculty Publications
Electrical properties of p-Ge1−ySny (y = 0.06%) grown on n-Si substrate were investigated through temperature-dependent Hall-effect measurements. It was found that there exists a degenerate parallel conducting layer in Ge1−ySny/Si and a second, deeper acceptor in addition to a shallow acceptor. This parallel conducting layer dominates the electrical properties of the Ge1−ySny layer below 50 K and also significantly affects those properties at higher temperatures. Additionally, a conductivity type conversion from p to n was observed around 370 K for this sample. A two-layer conducting model was used …
Equilibrium Magnetic States In Individual Hemispherical Permalloy Caps,
2012
Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden
Equilibrium Magnetic States In Individual Hemispherical Permalloy Caps, Robert Streubel, Volodymyr P. Kravchuk, Denis D. Sheka, Denys Makarov, Florian Kronast, Oliver G. Schmidt, Yuri Gaididei
Robert Streubel Papers
The magnetization distributions in individual soft magnetic permalloy caps on non-magnetic spherical particles with sizes ranging from 50 to 800nm are investigated. We experimentally visualize the magnetic structures at the resolution limit of the x-ray magnetic circular dichroism photoelectron emission microscopy (XMCD-PEEM). By analyzing the so-called tail contrast in XMCD-PEEM, the spatial resolution is significantly enhanced, which allowed us to explore magnetic vortices and their displacement on curved surfaces. Furthermore, cap nanostructures are modeled as extruded hemispheres to determine theoretically the phase diagram of equilibrium magnetic states. The calculated phase diagram agrees well with the experimental observations. © 2012 American …
Precision Measurement Of The 6he Half-Life And The Weak Axial Current In Nuclei,
2012
University of Washington
Precision Measurement Of The 6he Half-Life And The Weak Axial Current In Nuclei, A. Knecht, R. Hong, D. W. Zumwalt, B. G. Delbridge, A. García, P. Müller, H. E. Swanson, I. S. Towner, S. Utsuno, William Williams, C. Wrede
Physics: Faculty Publications
Background: The β decays of 3H and 6He can play an important role in testing nuclear wave-function calculations and fixing low-energy constants in effective-field theory approaches. However, there exists a large discrepancy between previous measurements of the 6He half-life. Purpose: Our measurement aims at resolving this long-standing discrepancy in the 6He half-life and providing a reliable ft value and Gamow-Teller matrix element for comparison with theoretical ab initio calculations. Method: We measured the 6He half-life by counting the β-decay electrons with two scintillator detectors operating in coincidence. Results: The measured 6He half-life is 806.89±0.11 stat-0.19+0.23syst ms corresponding to a relative …
Open Structure Zno/Cdse Core/Shell Nanoneedle Arrays For Solar Cells,
2012
Portland State University
Open Structure Zno/Cdse Core/Shell Nanoneedle Arrays For Solar Cells, Yanxue Chen, Lin Wei, Guanghua Zhang, Jun Jiao
Physics Faculty Publications and Presentations
Open structure ZnO/CdSe core/shell nanoneedle arrays were prepared on a conducting glass (SnO2:F) substrate by solution deposition and electrochemical techniques. A uniform CdSe shell layer with a grain size of approximately several tens of nanometers was formed on the surface of ZnO nanoneedle cores after annealing at 400°C for 1.5 h. Fabricated solar cells based on these nanostructures exhibited a high short-circuit current density of about 10.5 mA/cm2 and an overall power conversion efficiency of 1.07% with solar illumination of 100 mW/cm2. Incident photo-to-current conversion efficiencies higher than 75% were also obtained.
Sequential Ionization And Energy Gain Of Bound Electrons In Classical Modeling Of Atoms In Strong Laser Fields,
2012
Calvin University
Sequential Ionization And Energy Gain Of Bound Electrons In Classical Modeling Of Atoms In Strong Laser Fields, Stanley L. Haan, K. N. Shomsky, N. A. Danks
University Faculty Publications and Creative Works
Classical mechanics and classical ensembles have provided numerous insights into the dynamics of strong-field double ionization. In this paper, we show that in classical multidimensional modeling, the laser intensity at which sequential ionization begins to dominate depends on the softening of the interaction between the electron and nucleus. We show that an unsoftened interaction in two or three dimensions can lead to classical orbits in which an electron can start deep in the nuclear potential-energy well, gain energy from the oscillating laser field, and ionize over the barrier without any recollision. We discuss how this energy gain occurs, with the …
Performances And Future Plans Of The Lhc Rf,
2012
CERN
Performances And Future Plans Of The Lhc Rf, P. Baudrenghien, T. Mastoridis
Physics
The ramp-up of the LHC operation has been exceptionally fast: from the first acceleration of a single bunch at nominal intensity (1.1E11 p) to 3.5 TeV/c on May 2010, to the accumulation of 11 fb-1 integrated luminosity two years later (June 2012). On the RF side this was made possible by a few key design choices and several developments, that allow reliable LHC operation with 0.35 A DC beam at 4 TeV/c (1380 bunches at 50 ns spacing, 1.5E11 p per bunch). This paper reviews the RF design and presents its performance. Plans are also outlined that would allow operation …
Lhc Impedance Model: Experience With High Intensity Operation In The Lhc,
2012
CERN
Lhc Impedance Model: Experience With High Intensity Operation In The Lhc, B. Salvant, O. Aberle, G. Arduini, R. Assmann, V. Baglin, M.J. Barnes, P. Baudrenghien, A. Bertarelli, C. Bracco, R. Bruce, X. Buffat, F. Carra, G. Cattenoz, F. Caspers, S. Claudet, H. Day, J. Esteban Mueller, M. Garlasché, L. Gentini, B. Goddard, A. Grudiev, B. Henrist, W. Herr, S. Jakobsen, R. Jones, G. Lanza, L. Lari, T. Mastoridis, E. Métral, N. Mounet, A. Nosych, J.L Nougaret, S. Persichelli, T. Pieloni, A.M. Piguiet, S. Redaelli, F. Roncarolo, G. Rumolo, B. Salvachua, M. Sapinski, E. Shaposhnikova, L. Tavian, M. Timmins, J. Uythoven, A. Vidal, R. Wasef, D. Wollman, A. Burov, S. White
Physics
The CERN Large Hadron Collider (LHC) is now in luminosity production mode and has been pushing its performance in the past months by increasing the proton beam brightness, the collision energy and the machine availability. As a consequence, collective effects have started to become more and more visible and have effectively slowed down the performance increase of the machine. Among these collective effects, the interaction of brighter LHC bunches with the longitudinal and transverse impedance of the machine has been observed to generate beam induced heating, as well as longitudinal and transverse instabilities since 2010. This contribution reviews the current …
Measurements Of The Lhc Longitudinal Resistive Impedance With Beam,
2012
CERN
Measurements Of The Lhc Longitudinal Resistive Impedance With Beam, J.F. Esteban Muller, T. Argyropoulos, T. Bohl, T. Mastoridis, N. Mounet, G. Papotti, B. Salvant, E. Shaposhnikova, D. Valuch
Physics
The resistive part of the longitudinal impedance contributes to the heat deposition on different elements in the LHC ring including the beam screens, where it has to be absorbed by the cryogenic system and can be a practical limitation for the maximum beam intensity. In this paper, we present the first measurements of the LHC longitudinal resistive impedance with beam, done through synchronous phase shift measurements duringMachine Development sessions in 2012. Synchronous phase shift is measured for different bunch intensities and lengths using the high-precision LHC Beam Phase Module and then data are post-processed to further increase the accuracy. The …
Influence Of Quantum Dot Structure On The Optical Properties Of Group Iv Materials Fabricated By Ion Implantation,
2012
The University of Western Ontario
Influence Of Quantum Dot Structure On The Optical Properties Of Group Iv Materials Fabricated By Ion Implantation, Eric G. Barbagiovanni
Electronic Thesis and Dissertation Repository
In nanostructures (NSs), to acquire a fundamental understanding of the electronic states by studying the optical properties is inherently complicated. A widely used simplification to this problem comes about by developing a model for a small scale representation of types of NSs and applying it to a hierarchy of fabrication methods. However, this methodology fails to account for structural differences incurred by the fabrication method that lead to differences in the optical properties. Proper modelling is realized by first considering the proper range of experimental parameters individually as inputs to a theoretical model and applying the correct parameters to the …
Primordial Black Hole Evaporation And Spontaneous Dimensional Reduction,
2012
Loyola Marymount University
Primordial Black Hole Evaporation And Spontaneous Dimensional Reduction, Jonas R. Mureika
Physics Faculty Works
Several different approaches to quantum gravity suggest the effective dimension of spacetime reduces from four to two near the Planck scale. In light of such evidence, this Letter re-examines the thermodynamics of primordial black holes (PBHs) in specific lower-dimensional gravitational models. Unlike in four dimensions, (1 + 1)-D black holes radiate with power P ∼ M2BH, while it is known no (2+1)-D (BTZ) black holes can exist in a non-anti-de Sitter universe. This has important relevance to the PBH population size and distribution, and consequently on cosmological evolution scenarios. The number of PBHs that have evaporated to …
Serpentine Low Loss Trapezoidal Silica Waveguides On Silicon,
2012
University of Southern California
Serpentine Low Loss Trapezoidal Silica Waveguides On Silicon, Xiaomin Zhang, Mark Harrison, Audrey Harker, Andrea M. Armani
Engineering Faculty Articles and Research
We report the fabrication and characterization of straight and serpentine low loss trapezoidal silica waveguides integrated on a silicon substrate. The waveguide channel was defined using a dual photo-lithography and buffered HF etching and isolated from the silicon substrate using an isotropic silicon etchant. The waveguide is air-clad and thus has a core-cladding effective index contrast of approximately 25%. Measured at 658, 980 and 1550nm, the propagation loss was found to be 0.69, 0.59, and 0.41dB/cm respectively, with a critical bending radius less than 375μm. The waveguide’s polarization behavior was investigated both theoretically and experimentally. Additionally, the output power shows …
Experimental Study Of The P11(1440) And D13(1520) Resonances From The Clas Data On Ep→E′Π+Π−P′,
2012
University of Richmond
Experimental Study Of The P11(1440) And D13(1520) Resonances From The Clas Data On Ep→E′Π+Π−P′, V. I. Mokeev, Gerard P. Gilfoyle, Et. Al.
Physics Faculty Publications
The transition helicity amplitudes from the proton ground state to the P11(1440) and D13(1520) excited states (vγpN* electrocouplings) were determined from the analysis of nine independent one-fold differential π+π−p electroproduction cross sections off a proton target, taken with CLAS at photon virtualities of 0.25 < Q2 < 0.60 GeV2. The phenomenological reaction model was employed for separation of the resonant and nonresonant contributions to the final state. The P11(1440) and D13(1520) electrocouplings were obtained from the resonant amplitudes parametrized within the framework of a unitarized …
The Critical Coupling Likelihood Method: A New Approach For Seamless Integration Of Environmental And Operating Conditions Of Gravitational Wave Detectors Into Gravitational Wave Searches,
2012
The University of Texas Rio Grande Valley
The Critical Coupling Likelihood Method: A New Approach For Seamless Integration Of Environmental And Operating Conditions Of Gravitational Wave Detectors Into Gravitational Wave Searches, Cesar A. Costa, Cristina V. Torres
Physics and Astronomy Faculty Publications and Presentations
Any search effort for gravitational waves (GWs) using interferometric detectors like LIGO needs to be able to identify if and when noise couples into the detector’s output signal. The critical coupling likelihood (CCL) method has been developed to characterize potential noise coupling and in the future aid GW search efforts. By testing two hypotheses about pairs of channels, CCL is able to identify undesirable coupled instrumental noise from potential GW candidates. Our preliminary results show that CCL can associate up to ∼80% of observed artifacts with SNR ⩾ 8 with local noise sources, while reducing the duty cycle of the …
Energy Conservation In Large Buildings,
2012
University of California - Berkeley
Energy Conservation In Large Buildings, A. Rosenfeld, David W. Hafemeister
Anatoly Rozenfeld
As energy prices rise, newly energy aware designers use better tools and technology to create energy efficient buildings. Thus the U.S. office stock (average age 20 years) uses 250 kBTU/ft2 of resource energy, but the guzzler of 1972 uses 500 (up × 2), and the 1986 ASHRAE standards call for 100–125 (less than 25% of their 1972 ancestors). Surprisingly, the first real cost of these efficient buildings has not risen since 1972. Scaling laws are used to calculate heat gains and losses of buildings to obtain the ΔT(free) which can be as large as 15–30 °C (30–60 °F) for large …
Local Pt Invariance And Supersymmetric Parametric Oscillators,
2012
University of Toronto
Local Pt Invariance And Supersymmetric Parametric Oscillators, Ramy El-Ganainy, Konstantinos G. Makris, Demetrios N. Christodoulides
Ramy El-Ganainy
We introduce the concept of local parity-time symmetric (PT) invariance in optical waveguides (or cavity) structures. Starting from a Lagrangian formalism, we establish the connection between light dynamics in these configurations and the seemingly different physics of “supersymmetric” parametric oscillators. Using this powerful tool, we present analytical solutions for optical beam propagation in local PT-invariant coupled systems and we show that the intensity tunneling between the two channels critically depends on the initial conditions. For unbalanced inputs, symmetric as well as asymmetric power evolution can be observed depending on the excitation channel. On the other hand, under certain physical conditions, …
Progress On: “Coherent Terahertz Acoustic Phonon Scattering: Novel Diagnostic For Erosion In Plasma Thruster Discharge Chamber Walls",
2012
Marshall University
Progress On: “Coherent Terahertz Acoustic Phonon Scattering: Novel Diagnostic For Erosion In Plasma Thruster Discharge Chamber Walls", Thomas E. Wilson, Iain D. Boyd
Physics Faculty Research
The study is based on the success in obtaining the first experimental evidence for the direct excitation of coherent nanosecond-pulsed high-frequency acoustic phonons in semiconducting doping superstructures by electromagnetic fields of the same frequency. Acoustic phonons are detected by a superconducting bolometer, with nanosecond resolution, at the appropriate time-of-flight across a (100) silicon substrate for ballistic longitudinal phonons when a silicon delta-doped doping superlattice is illuminated with grating-coupled nanosecond-pulsed 246-GHz laser radiation with an approximate power density of 1 kW/mm2. The absorbed phonon power density in the bolometer detector is estimated to be 10 μW/mm2, in …
Topics In Field Theory,
2012
The University of Western Ontario
Topics In Field Theory, Alexander Patrushev
Electronic Thesis and Dissertation Repository
This thesis consists of different projects in classical and quantum field theory on a curved background which are connected by a common usage of theoretical ideas as well as cal- culation techniques. The introduction clarifies such connections. In the second chapter we apply the Dirac constraint formalism to the second and first order 1 + 1 dimensional gravitational action coupled to a scalar field. The third chapter is devoted to a calculation of the one loop effective action for a spinor field coupled to a constant background chiral vector field. In the fourth chapter we find a new expression for …
Mapping Nuclear Fallout Using The Weather Research & Forecasting (Wrf) Model,
2012
Air Force Institute of Technology
Mapping Nuclear Fallout Using The Weather Research & Forecasting (Wrf) Model, Joseph C. Schofield
Theses and Dissertations
There are many models that attempt to predict transport & dispersion (T&D) of particulate matter in the sensible atmosphere. The majority of these existing models are unable to incorporate atmospheric processes such wet deposition through scavenging and cloud condensation nuclei (CCN) formation. To this end, the numerical weather prediction (NWP) model known as the Weather Research & Forecasting with Chemistry (WRF/Chem) Model is studied to determine its suitability as a potential tool for predicting particulate T&D following an atmospheric nuclear detonation. This is done by modifying relevant modules, originally designed to predict the settling of volcanic ash, such that a …
Light Scattering Study Of Elongated Particles: From Inorganic Nanorice To Polypeptide Micelles,
2012
Cleveland State University
Light Scattering Study Of Elongated Particles: From Inorganic Nanorice To Polypeptide Micelles, Philip Dee
Undergraduate Research Posters 2012
Utilizing the powerful experimental technique of Dynamic Light Scattering (DLS) for size characterization of anisotropic particles can be extremely misleading. Unfortunately, this point is often not realized by researchers who strive for particle sizing of nanoparticles in suspensions. We present a consistent analysis of DDLS results on FeOOH nanorice and outline the potential difficulties and challenges of DDLS application for polypeptide micelles.
