49 Matching Results

Search Results

Results: 1 - 24 next
open access

MODELING OF NI-CR-MO BASED ALLOYS: PART II - KINETICS

Description: The CALPHAD approach is applied to kinetic studies of phase transformations and aging of prototypes of Ni-Cr-Mo-based alloys selected for waste disposal canisters in the Yucca Mountain Project (YMP). Based on a previous study on alloy stability for several candidate alloys, the thermodynamic driving forces together with a newly developed mobility database have been used to analyze diffusion-controlled transformations in these Ni-based alloys. Results on precipitation of the Ni{sub 2}Cr-ordered … more
Date: July 7, 2006
Creator: Turchi, P A; Kaufman, L & Liu, Z
Partner: UNT Libraries Government Documents Department
open access

High Pressure Materials Research using Advanced Third-Generation Synchrotron X-ray

Description: The recent discoveries of nonmolecular phases of simple molecular solids [1,2] demonstrate the proof-of-the-principles for producing exotic phases by application of high pressure. Modern advances in theoretical and computational methodologies now make possible to explain or even predict novel structures and properties in a relatively wide range of length scales on the basis of thermodynamic stability [3]. Equally important in materials research is the recent developments in advanced x-ray and l… more
Date: July 7, 2006
Creator: Yoo, C. S.; Iota, V.; Park, J.; Lee, G.; Evans, W.; Jenei, Z. et al.
Partner: UNT Libraries Government Documents Department
open access

Wakefield and RF Kicks Due to Coupler Asymmetry in TESLA-Type Accelerating Cavities

Description: In a future linear collider, such as the International Linear Collider (ILC), trains of high current, low emittance bunches will be accelerated in a linac before colliding at the interaction point. Asymmetries in the accelerating cavities of the linac will generate fields that will kick the beam transversely and degrade the beam emittance and thus the collider performance. In the main linac of the ILC, which is filled with TESLA-type superconducting cavities, it is the fundamental (FM) and high… more
Date: July 7, 2008
Creator: Bane, K. L. F.; Adolphsen, C.; Li, Z.; Dohlus, M.; Zagorodnov, I.; Gonin, I. et al.
Partner: UNT Libraries Government Documents Department
open access

Probing QCD with Rare Charmless $B$ Decays

Description: Rare charmless hadronic B decays are a good testing ground for QCD. In this paper we describe a selection of new measurements made by the BABAR and BELLE collaborations.
Date: July 7, 2006
Creator: Gradl, Wolfgang
Partner: UNT Libraries Government Documents Department
open access

The powers of deconfinement

Description: The trace anomaly of gluodynamics encodes the breakdown of classical scale invariance due to interactions around the deconfinement phase transition. While it is expected that at high temperatures perturbation theory becomes applicable we show that current lattice calculations are far from the perturbative regime and are dominated instead by inverse even power corrections in the temperature, while the total perturbative contribution is estimated to be extremely small and compatible with zero wit… more
Date: July 7, 2008
Creator: Megias,E.; Ruiz Arriola, E.; Megias, E. & Salcedo, L.L.
Partner: UNT Libraries Government Documents Department
open access

SABER Optical Design

Description: SABER, the South Arc Beam Experimental Region, is a proposed new beam line facility designed to replace the Final Focus Test Beam at SLAC. In this paper, we outline the optical design features and beam parameters now envisioned for SABER. A magnetic chicane to compress positron bunches for SABER and a bypass line that could transport electrons or positrons from the two-thirds point of the linac to SABER, bypassing the LCLS systems, are also discussed.
Date: July 7, 2006
Creator: Erickson, R.; Bane, K.; Emma, P. & Nosochkov, Y.
Partner: UNT Libraries Government Documents Department
open access

SNAP Satellite Focal Plane Development

Description: The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to a… more
Date: July 7, 2003
Creator: Bebek, C.; Akerlof, C.; Aldering, G.; Amanullah, R.; Astier, P.; Baltay, C. et al.
Partner: UNT Libraries Government Documents Department
open access

Measurements and Analysis of Longitudinal HOM Driven Coupled Bunch Modes in PEP-II Rings

Description: The growth rates of the longitudinal higher-order impedance-driven beam modes have greatly increased since the initial PEP-II design and commissioning. This increase is attributed to the addition of 6 1.2MW RF stations with 8 accelerating cavities in the HER and 2 1.2MW RF stations with 4 accelerating cavities in the LER, which allowed operations at twice the design current and almost four times the luminosity. As a result, the damping requirements for the longitudinal feedback have greatly inc… more
Date: July 7, 2008
Creator: Mastorides, T; Rivetta, C.; Fox, J. D. & Winkle, D. Van
Partner: UNT Libraries Government Documents Department
open access

Modeling and Simulation of the Longitudinal Beam Dynamics - RF Station Interaction in the LHC Rings

Description: A non-linear time-domain simulation has been developed to study the interaction between longitudinal beam dynamics and RF stations in the LHC rings. The motivation for this tool is to determine optimal LLRF configurations, to study system sensitivity on various parameters, and to define the operational and technology limits. It will be also used to study the effect of RF station noise, impedance, and perturbations on the beam life time and longitudinal emittance. It allows the study of alternat… more
Date: July 7, 2008
Creator: Mastorides, T; Rivetta, C.; Fox, J. D.; Winkle, D.Van; Baudrenghien, P. & Tuckmantel, J.
Partner: UNT Libraries Government Documents Department
open access

Design of a combinatorial dna microarray for protein-dnainteraction studies

Description: Background: Discovery of precise specificity oftranscription factors is an important step on the way to understandingthe complex mechanisms of gene regulation in eukaryotes. Recently,doublestranded protein-binding microarrays were developed as apotentially scalable approach to tackle transcription factor binding siteidentification. Results: Here we present an algorithmic approach toexperimental design of a microarray that allows for testing fullspecificity of a transcription factor binding to a… more
Date: July 7, 2006
Creator: Mintseris, Julian & Eisen, Michael B.
Partner: UNT Libraries Government Documents Department
open access

Analysis of Longitudinal Beam Dynamics Behavior and RF System Operative Limits at High Beam Currents in Storage Rings

Description: A dynamics simulation model is used to estimate limits of performance of the Positron-Electron Project (PEP-II). The simulation captures the dynamics and technical limitations of the Low Level Radio Frequency (LLRF) system, the high-power RF components and the low-order mode coupled bunch longitudinal beam dynamics. Simulation results showing the effect of non-linearities on the LLRF loops, and studies of the effectiveness of technical component upgrades are reported, as well as a comparison of… more
Date: July 7, 2008
Creator: Mastorides, T; Rivetta, C.; Fox, J. D.; Winkle, D. Van & Tytelman, D.
Partner: UNT Libraries Government Documents Department
open access

Sunfall: a collaborative visual analytics system for astrophysics

Description: Computational and experimental sciences produce and collect ever-larger and complex datasets, often in large-scale, multi-institution projects. The inability to gain insight into complex scientific phenomena using current software tools is a bottleneck facing virtually all endeavors of science. In this paper, we introduce Sunfall, a collaborative visual analytics system developed for the Nearby Supernova Factory, an international astrophysics experiment and the largest data volume supernova sea… more
Date: July 7, 2008
Creator: Aragon, Cecilia R.; Aragon, Cecilia R.; Bailey, Stephen J.; Poon, Sarah; Runge, Karl & Thomas, Rollin C.
Partner: UNT Libraries Government Documents Department
open access

5000 groove/mm multilayer-coated blazed grating with 33percent efficiency in the 3rd order in the EUV wavelength range

Description: We report on recent progress in developing diffraction gratings which can potentially provide extremely high spectral resolution of 105-106 in the EUV and soft x-ray photon energy ranges. Such a grating was fabricated by deposition of a multilayer on a substrate which consists ofa 6-degree blazed grating with a high groove density. The fabrication of the substrate gratings was based on scanning interference lithography and anisotropic wet etch of silicon single crystals. The optimized fabricati… more
Date: July 7, 2009
Creator: Lawrence Berkeley National Laboratory. Advanced Light Source.
Partner: UNT Libraries Government Documents Department
open access

High resolution angle-resolved photoemission study of hightemperature superconductors: charge-ordering, bilayer splitting andelectron-phonon coupling

Description: The latest development of angle-resolved photoemission spectroscopy (ARPES) technique has seen extremely high energy resolution and momentum resolution, as well as multiple angle detection. These advancements have led to new findings through efficient Fermi surface mapping, fine electronic structure resolving, and direct determination of electron self-energy. In this paper, we will highlight some recent high resolution ARPES work on high temperature superconductors. These include: (1) charge-or… more
Date: July 7, 2003
Creator: Zhou, Xingjiang; Hussain, Zahid & Shen, Zhi-xun
Partner: UNT Libraries Government Documents Department
open access

Advanced 0.3-NA EUV lithography capabilities at the ALS

Description: For volume nanoelectronics production using Extreme ultraviolet (EUV) lithography [1] to become a reality around the year 2011, advanced EUV research tools are required today. Microfield exposure tools have played a vital role in the early development of EUV lithography [2-4] concentrating on numerical apertures (NA) of 0.2 and smaller. Expected to enter production at the 32-nm node with NAs of 0.25, EUV can no longer rely on these early research tools to provide relevant learning. To overcome … more
Date: July 7, 2005
Creator: Naulleau, Patrick; Anderson, Erik; Dean, Kim; Denham, Paul; Goldberg, Kenneth A.; Hoef, Brian et al.
Partner: UNT Libraries Government Documents Department
open access

REGIONAL SEISMIC CHEMICAL AND NUCLEAR EXPLOSION DISCRIMINATION: WESTERN U.S. EXAMPLES

Description: We continue exploring methodologies to improve regional explosion discrimination using the western U.S. as a natural laboratory. The western U.S. has abundant natural seismicity, historic nuclear explosion data, and widespread mine blasts, making it a good testing ground to study the performance of regional explosion discrimination techniques. We have assembled and measured a large set of these events to systematically explore how to best optimize discrimination performance. Nuclear explosions … more
Date: July 7, 2006
Creator: Walter, W R; Taylor, S R; Matzel, E; Gok, R; Heller, S & Johnson, V
Partner: UNT Libraries Government Documents Department
open access

Berkeley Accelerator Space Effects (BASE) Light Ion FacilityUpgrade

Description: The BASE Light Ion Facility upgrades have been completed. All proton beams are now delivered to Cave 4A. New control software, a larger diameter beam window, and improved quality assurance measures have been added.
Date: July 7, 2006
Creator: Johnson, Michael B.; McMahan, Margaret A.; Gimpel, Thomas L. & Tiffany, William S.
Partner: UNT Libraries Government Documents Department
open access

Design and Operation of a tunable MeV-level Compton-scattering-based (gamma-ray) source

Description: A mono-energetic gamma-ray (MEGa-ray) source based on Compton-scattering, targeting nuclear physics applications such as nuclear resonance fluorescence, has been constructed and commissioned at Lawrence Livermore National Laboratory. In this paper, the overall architecture of the system, as well as some of the critical design decisions made in the development of the source, are discussed. The performances of the two laser systems (one for electron production, one for scattering), the electron p… more
Date: July 7, 2009
Creator: Gibson, D. J.; Albert, F.; Anderson, S. G.; Betts, S. M.; Messerly, M. J.; Phan, H. H. et al.
Partner: UNT Libraries Government Documents Department
open access

Binary pseudo-random gratings and arrays for calibration of the modulation transfer function of surface profilometers: recent developments

Description: The major problem of measurement of a power spectral density (PSD) distribution of the surface heights with surface profilometers arises due to the unknown Modulation Transfer Function (MTF) of the instruments. The MTF tends to distort the PSD at higher spatial frequencies. It has been suggested [Proc. SPIE 7077-7, (2007), Opt. Eng. 47 (7), 073602-1-5 (2008)] that the instrumental MTF of a surface profiler can be precisely measured using standard test surfaces based on binary pseudo-random (BPR… more
Date: July 7, 2009
Creator: Barber, Samuel K.; Soldate, Paul; Anderson, Erik H.; Cambie, Rossana; Marchesini, Stefano; McKinney, Wanye R. et al.
Partner: UNT Libraries Government Documents Department
open access

Thermal Instability of Olivine-Type LiMnP04 Cathodes

Description: The remarkable thermal stability of LiFePO{sub 4} and its charged counterpart, FePO{sub 4}, have been instrumental in its commercialization as a lithium ion battery cathode material. Despite the similarity in composition and structure, and despite the high thermal stability of the parent compound, LiMnPO{sub 4}, we find that the delithiated phase Li{sub y}MnPO{sub 4}, (which contains a small amount of residual lithium), is relatively unstable and reactive toward a lithium ion electrolyte. The o… more
Date: July 7, 2009
Creator: Chen, Guoying & Richardson, Thomas J.
Partner: UNT Libraries Government Documents Department
open access

High pressure phase transformation in iron under fast compression

Description: We present experimental results on the solid-solid, {alpha} to {epsilon} phase transformation kinetics of iron under high pressure dynamic compression. We observe kinetic features - velocity loops - similar with the ones recently reported to occur when water is frozen into its ice VII phase under comparable experimental conditions. We analyze this behavior in terms of general ideas coupling the steady sample compression with phase nucleation and growth with a pressure dependent phase interface … more
Date: July 7, 2009
Creator: Bastea, M; Bastea, S & Becker, R
Partner: UNT Libraries Government Documents Department
Back to Top of Screen