Search Results

open access

Black ring deconstruction

Description: We present a sample microstate for a black ring in four and five dimensional language. The microstate consists of a black string microstate with an additional D6-brane. We show that with an appropriate choice of parameters the piece involving the black string microstate falls down a long AdS throat, whose M-theory lift is AdS_3 x S2. We wrap a spinning dipole M2-brane on the S2 in the probe approximation. In IIA, this corresponds to a dielectric D2-brane carrying only D0-charge. We conjecture t… more
Date: June 22, 2007
Creator: Gimon, Eric; Gimon, Eric G. & Levi, Thomas S.
Partner: UNT Libraries Government Documents Department
open access

Galaxy Mergers with Adaptive Mesh Refinement: Star Formation and Hot Gas Outflow

Description: In hierarchical structure formation, merging of galaxies is frequent and known to dramatically affect their properties. To comprehend these interactions high-resolution simulations are indispensable because of the nonlinear coupling between pc and Mpc scales. To this end, we present the first adaptive mesh refinement (AMR) simulation of two merging, low mass, initially gas-rich galaxies (1.8 x 10{sup 10} M{sub {circle_dot}} each), including star formation and feedback. With galaxies resolved by… more
Date: June 22, 2011
Creator: Kim, Ji-hoon; /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Wise, John H.; /NASA, Goddard; Abel, Tom & /KIPAC, Menlo Park /Stanford U., Phys. Dept.
Partner: UNT Libraries Government Documents Department
open access

ABSOLUTE BUNCH LENGTH MEASUREMENTS AT THE ALS BY INCOHERENTSYNCHROTRON RADIATION FLUCTUATION ANALYSIS

Description: By analysing the pulse to pulse intensity fluctuations ofthe radiation emitted by a charge particle in the incoherent part of thespectrum, it is possible to extract information about the spatialdistribution of the beam. At the Advanced Light Source (ALS) of theLawrence Berkeley National Laboratory, we have developed and tested asimple scheme based on this principle that allows for the absolutemeasurement of the bunch length. A description of the method and theexperimental results are presented.
Date: June 22, 2007
Creator: Sannibale, Fernando; Zolotorev, Max S.; Filippetto, Daniele & Stupakov, Gennady V.
Partner: UNT Libraries Government Documents Department
open access

ALE3D Simulations of Gap Closure and Surface Ignition for Cookoff Modeling

Description: We are developing ALE3D models to describe the thermal, chemical and mechanical behavior during the heating, ignition and explosive phases of various cookoff phenomena. The candidate models and numerical strategies are being evaluated using benchmark cookoff experiments. ALE3D is a three-dimensional computer code capable of solving the model equations in a coupled fashion through all the phases of the cookoff in a single calculation. For the cookoff experiments, we are interested in representin… more
Date: June 22, 2006
Creator: Howard, W. M.; McClelland, M. A. & Nichols, A. L.
Partner: UNT Libraries Government Documents Department
open access

Progress on Modeling of Ultrafast X-Ray Streak Cameras

Description: Streak cameras continue to be useful tools for studying phenomena on the picoseconds time scale. We have employed accelerator modeling tools to understand and possibly improve the time resolution of present and future streak cameras. This effort has resulted in an end-to-end model of the camera. This model has contributed to the recent measurement of 230 fsec (FWHM) resolution measured at 266 nm in the Advanced Light Source Streak Camera Laboratory. We describe results from this model that show… more
Date: June 22, 2007
Creator: Huang, G.; Byrd, J.M.; Feng, J.; Qiang, J. & Wang, W.
Partner: UNT Libraries Government Documents Department
open access

Progress on H5Part: A Portable High Performance Parallel DataInterface for Electromagnetics Simulations

Description: Significant problems facing all experimental andcomputationalsciences arise from growing data size and complexity. Commonto allthese problems is the need to perform efficient data I/O ondiversecomputer architectures. In our scientific application, thelargestparallel particle simulations generate vast quantitiesofsix-dimensional data. Such a simulation run produces data foranaggregate data size up to several TB per run. Motived by the needtoaddress data I/O and access challenges, we have impleme… more
Date: June 22, 2007
Creator: Adelmann, Andreas; Gsell, Achim; Oswald, Benedikt; Schietinger,Thomas; Bethel, Wes; Shalf, John et al.
Partner: UNT Libraries Government Documents Department
open access

New Results From the LASS (Large Aperture Superconducting Solenoid) Spectrometer

Description: New results are presented from analyses of several mesonic and baryonic states containing one or more strange quarks. The data are taken from a high statistics (4 events/nb) study of K p interactions at 11 GeV/c carried out in the LASS Spectrometer at SLAC. New information is reported on the underlying K* states and also evidence for selective coupling of K eta to the K*'s; on the strangeonium members of the axial vector nonets in the K anti K channel; and on evidence for an * state.
Date: June 22, 1987
Creator: Aston, D.; Awaji, N.; Bienz, T.; Bird, F.; D'Amore, J.; Dunwoodie, W. et al.
Partner: UNT Libraries Government Documents Department
open access

Use of ORACLE in a scientific environment

Description: This paper discusses the use of ORACLE at the Fusion Experiments Analysis Facility (FEAF) for the laser program of the Lawrence Livermore National Laboratory. The mission of this VAX based computing facility is to aid laser program scientists and engineers develop their understanding of inertial confinement fusion target behavior. We have incorporated the ORACLE DBMS as a major part of an integrated data management and analysis environment for accomplishing this task. We discuss our use of ORAC… more
Date: June 22, 1983
Creator: Carey, R. W.; Auerbach, J. M.; Lerche, R. A. & Demartini, B. J.
Partner: UNT Libraries Government Documents Department
open access

Transport of intense particle beams with application to heavy ion fusion

Description: An attractive feature of the high energy (> GeV) heavy ion beam approach to inertial fusion, as compared with other particle beam systems, is the relative simplicity involved in the transport and focusing of energy on the target inside a reactor chamber. While this focusing could be done in vacuum by conventional methods with multiple beams, there are significant advantages in reactor design if one can operate at gas pressures around one torr. In this paper we summarize the results of our studi… more
Date: June 22, 1979
Creator: Buchanan, H. L.; Chambers, F. W.; Lee, E. P.; Yu, S. S.; Briggs, R. J. & Rosenbluth, M. N.
Partner: UNT Libraries Government Documents Department
open access

Applications of intelligent-measurement systems in controlled-fusion research

Description: The paper describes the control and instrumentation for the Mirror Fusion Test Facility at the Lawrence Livermore National Laboratory, California, USA. This large-scale scientific experiment in controlled thermonuclear fusion, which is currently being expanded, originally had 3000 devices to control and 7000 sensors to monitor. A hierarchical computer control system, is used with nine minicomputers forming the supervisory system. There are approximately 55 local control and instrumentation micr… more
Date: June 22, 1981
Creator: Owen, E. W.; Shimer, D. W.; Lindquist, W. B.; Peterson, R. L. & Wyman, R. H.
Partner: UNT Libraries Government Documents Department
open access

Cooperative bi-exponential decay of dye emission coupled via plasmons

Description: This article demonstrates that the relaxation in the sub-radiant system leads to the population of the sub-radiant states by dephasing the super-radiant Dicke states giving rise to the bi-exponential decay in agreement with the experiments.
Date: June 22, 2018
Creator: Lyvers, David P.; Moazzezi, Mojtaba; de Silva, Vashista C.; Brown, Dean P.; Urbas, Augustine M.; Rostovtsev, Yuri V. et al.
Partner: UNT College of Science
open access

Contrasts in One- and Two-Dimensional Hydrocode Calculations of Laser-Generated Shockwaves in Disk Targets

Description: A comparison is made between 1D and 2D hydrocode calculations and some recent experimental results on laser-driven planar shockwaves in disk targets. A simple model is described which accounts for the trends seen in the calculations and which gives insight into the regime of laser intensity and pulse duration where two-dimensional effects become significant in these experiments.
Date: June 22, 1981
Creator: Harrach, R. J.; Lee, Y. T.; Trainor, R. J.; Holmes, N. C.; Rosen, M. D.; Banner, D. L. et al.
Partner: UNT Libraries Government Documents Department
open access

High- and low-temperature bonding techniques for microstructures

Description: The ability to bond together two or more silicon wafers greatly expands the variety and complexity of silicon microstructures that can be designed and fabricated. At LLNL, microstructures have been used for many years as hardware in scientific experiments. The activity has recently been expanded into other areas to include microinstruments for biomedical applications and for chemical analysis. Both high temperature (1100{degrees}C) bonding techniques have been used, depending on the application… more
Date: June 22, 1993
Creator: Ciarlo, D. R.
Partner: UNT Libraries Government Documents Department
open access

Some considerations for geothermal district heating

Description: The distribution of geothermal resources in relation to the location of population centers in the U.S. is considered. Capital aspects of district heating systems are discussed. Estimates are given of distribution network capital investment as a function of population in service area. Swedish and Icelandic cost experience is taken into consideration. The need for more specific assessment of the potential for direct use of geothermal energy is cited. (JGB)
Date: June 22, 1977
Creator: Karkheck, J.
Partner: UNT Libraries Government Documents Department
open access

Generic Model Host System Design

Description: There are many simulation codes for accelerator modelling; each one has some strength but not all. A platform which can host multiple modelling tools would be ideal for various purposes. The model platform along with infrastructure support can be used not only for online applications but also for offline purposes. Collaboration is formed for the effort of providing such a platform. In order to achieve such a platform, a set of common physics data structure has to be set. Application Programming… more
Date: June 22, 2012
Creator: Chu, Chungming; Wu, Juhao; Qiang, Ji & Shen, Guobao
Partner: UNT Libraries Government Documents Department
open access

Studies of Space Charge Effects in the Proposed CERN PS2

Description: A new proton synchrotron, the PS2, is under design study to replace the current proton synchrotron at CERN for the LHC upgrade. Nonlinear space charge effects could cause significant beam emittance growth and particle losses and limit the performance of the PS2. In this paper, we report on studies of the potential space-charge effects at the PS2 using three-dimensional self-consistent macroparticle tracking codes, IMPACT, MaryLie/IMPACT, and Synergia. We will present initial benchmark results a… more
Date: June 22, 2012
Creator: Qiang, Ji; Ryne, Robert; De Maria, Riccardo; Macridin, Alexandru; Spentzouris, Panagiotis; Papaphilippou, Yannis et al.
Partner: UNT Libraries Government Documents Department
open access

CHARACTERIZATION OF PD IMPURITIES AND TWIN BOUNDARY DEFECTS IN DETECTOR GRADE CDZNTE CRYSTALS

Description: Synthetic CdZnTe or ''CZT'' crystals are highly suitable for {gamma}-spectrometers operating at the room temperature. Secondary phases (SP) in CZT are known to inhibit detector performance, particularly when they are present in large numbers or dimensions. These SP may exist as voids or composites of non-cubic phase metallic Te layers with bodies of polycrystalline and amorphous CZT material and voids. Defects associated with crystal twining may also influence detector performance in CZT. Using… more
Date: June 22, 2011
Creator: Duff, M.
Partner: UNT Libraries Government Documents Department
open access

Simulating Complex Window Systems using BSDF Data

Description: Nowadays, virtual models are commonly used to evaluate the performance of conventional window systems. Complex fenestration systems can be difficult to simulate accurately not only because of their geometry but also because of their optical properties that scatter light in an unpredictable manner. Bi-directional Scattering Distribution Functions (BSDF) have recently been developed based on a mixture of measurements and modelling to characterize the optics of such systems. This paper describes t… more
Date: June 22, 2009
Creator: Konstantoglou, Maria; Jonsson, Jacob & Lee, Eleanor
Partner: UNT Libraries Government Documents Department
open access

Breaking the Attosecond, Angstrom and TV/M Field Barriers with Ultra-Fast Electron Beams

Description: Recent initiatives at UCLA concerning ultra-short, GeV electron beam generation have been aimed at achieving sub-fs pulses capable of driving X-ray free-electron lasers (FELs) in single-spike mode. This use of very low Q beams may allow existing FEL injectors to produce few-100 attosecond pulses, with very high brightness. Towards this end, recent experiments at the LCLS have produced {approx}2 fs, 20 pC electron pulses. We discuss here extensions of this work, in which we seek to exploit the b… more
Date: June 22, 2012
Creator: Rosenzweig, James; Andonian, Gerard; Fukasawa, Atsushi; Hemsing, Erik; Marcus, Gabriel; Marinelli, Agostino et al.
Partner: UNT Libraries Government Documents Department
open access

CSR Fields: Direct Numerical Solution of the Maxwell___s Equation

Description: We discuss the properties of the coherent electromagnetic fields of a very short, ultra-relativistic bunch in a rectangular vacuum chamber inside a bending magnet. The analysis is based on the results of a direct numerical solution of Maxwell's equations together with Newton's equations. We use a new dispersion-free time-domain algorithm which employs a more efficient use of finite element mesh techniques and hence produces self-consistent and stable solutions for very short bunches. We investi… more
Date: June 22, 2011
Creator: Novokhatski, A.
Partner: UNT Libraries Government Documents Department
open access

Driving Missing Data at Next-to-Leading Order

Description: The prediction of backgrounds to new physics signals in topologies with large missing transverse energy and jets is important to new physics searches at the LHC. Following a CMS study, we investigate theoretical issues in using measurements of {gamma} + 2-jet production to predict the irreducible background to searches for missing energy plus two jets that originates from Z + 2-jet production where the Z boson decays to neutrinos. We compute ratios of {gamma} + 2-jet to Z + 2-jet production cro… more
Date: June 22, 2011
Creator: Bern, Z.; Diana, G.; Dixon, L. J.; Febres Cordero, F.; Hoeche, S.; Ita, H. et al.
Partner: UNT Libraries Government Documents Department
open access

Degradation of Bimetallic Model Electrocatalysts ___ an in situ XAS Study

Description: One of the major challenges in the development of clean energy fuel cells is the performance degradation of the electrocatalyst, which, apart from poisoning effects, can suffer from corrosion due to its exposure to a harsh environment under high potentials. In this communication, we demonstrate how interactions of Pt with a transition metal support affect not only, as commonly intended, the catalytic activity, but also the reactivity of Pt towards oxide formation or dissolution. We use two well… more
Date: June 22, 2011
Creator: Friebel, Daniel
Partner: UNT Libraries Government Documents Department
open access

Novel QCD Phenomena at the LHeC

Description: The proposed electron-proton/ion collider at CERN, the LHeC, can test fundamental and novel aspects of QCD and electroweak interactions as well as explore physics beyond the standard model over an exceptionally large kinematic range.
Date: June 22, 2011
Creator: Brodsky, Stanley J. & /SLAC /Southern Denmark U., CP3-Origins
Partner: UNT Libraries Government Documents Department
open access

Meson Transition Form Factors in Light-Front Holographic QCD

Description: We study the photon-to-meson transition form factors (TFFs) F{sub M{gamma}}(Q{sup 2}) for {gamma}{gamma}* {yields} M using light-front holographic methods. The Chern-Simons action, which is a natural form in 5-dimensional anti-de Sitter (AdS) space, leads directly to an expression for the photon-to-pion TFF for a class of confining models. Remarkably, the predicted pion TFF is identical to the leading order QCD result where the distribution amplitude has asymptotic form. The Chern-Simons form i… more
Date: June 22, 2011
Creator: Brodsky, Stanley J.; Cao, Fu-Guang & de Teramond, Guy F.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen