Isochoric Implosions for Fast Ignition (open access)

Isochoric Implosions for Fast Ignition

Various gain models have shown the potentially great advantages of Fast Ignition (FI) Inertial Confinement Fusion (ICF) over its conventional hot spot ignition counterpart [e.g., S. Atzeni, Phys. Plasmas 6, 3316 (1999); M. Tabak et al., Fusion Sci. & Technology 49, 254 (2006)]. These gain models, however, all assume nearly uniform-density fuel assemblies. In contrast, conventional ICF implosions yield hollowed fuel assemblies with a high-density shell of fuel surrounding a low-density, high-pressure hot spot. Hence, to realize fully the advantages of FI, an alternative implosion design must be found which yields nearly isochoric fuel assemblies without substantial hot spots. Here, it is shown that a self-similar spherical implosion of the type originally studied by Guderley [Luftfahrtforschung 19, 302 (1942)] may be employed to yield precisely such quasi-isochoric imploded states. The difficulty remains, however, of accessing these self-similarly imploding configurations from initial conditions representing an actual ICF target, namely a uniform, solid-density shell at rest. Furthermore, these specialized implosions must be realized for practicable drive parameters and at the scales and energies of interest in ICF. A direct-drive implosion scheme is presented which meets all of these requirements and reaches a nearly isochoric assembled density of 300 g=cm{sup 3} and areal …
Date: April 4, 2007
Creator: Clark, D S & Tabak, M
Object Type: Article
System: The UNT Digital Library
USING WET AIR OXIDATION TECHNOLOGY TO DESTROY TETRAPHENYLBORATE (open access)

USING WET AIR OXIDATION TECHNOLOGY TO DESTROY TETRAPHENYLBORATE

A bench-scale feasibility study on the use of a Wet Air Oxidation (WAO) process to destroy a slurry laden with tetraphenylborate (TPB) compounds has been undertaken. WAO is an aqueous phase process in which soluble and/or insoluble waste constituents are oxidized using oxygen or oxygen in air at elevated temperatures and pressures ranging from 150 C and 1 MPa to 320 C and 22 MPa. The products of the reaction are CO{sub 2}, H{sub 2}O, and low molecular weight oxygenated organics (e.g. acetate, oxalate). Test results indicate WAO is a feasible process for destroying TPB, its primary daughter products [triphenylborane (3PB), diphenylborinic acid (2PB), and phenylboronic acid (1PB)], phenol, and most of the biphenyl byproduct. The required conditions are a temperature of 300 C, a reaction time of 3 hours, 1:1 feed slurry dilution with 2M NaOH solution, the addition of CuSO{sub 4}.5H{sub 2}O solution (500 mg/L Cu) as catalyst, and the addition of 2000 mL/L of antifoam. However, for the destruction of TPB, its daughter compounds (3PB, 2PB, and 1PB), and phenol without consideration for biphenyl destruction, less severe conditions (280 C and 1-hour reaction time with similar remaining above conditions) are adequate.
Date: April 4, 2007
Creator: Adu-Wusu, K; Daniel McCabe, D & Bill Wilmarth, B
Object Type: Article
System: The UNT Digital Library
Scientific Computing Kernels on the Cell Processor (open access)

Scientific Computing Kernels on the Cell Processor

The slowing pace of commodity microprocessor performance improvements combined with ever-increasing chip power demands has become of utmost concern to computational scientists. As a result, the high performance computing community is examining alternative architectures that address the limitations of modern cache-based designs. In this work, we examine the potential of using the recently-released STI Cell processor as a building block for future high-end computing systems. Our work contains several novel contributions. First, we introduce a performance model for Cell and apply it to several key scientific computing kernels: dense matrix multiply, sparse matrix vector multiply, stencil computations, and 1D/2D FFTs. The difficulty of programming Cell, which requires assembly level intrinsics for the best performance, makes this model useful as an initial step in algorithm design and evaluation. Next, we validate the accuracy of our model by comparing results against published hardware results, as well as our own implementations on a 3.2GHz Cell blade. Additionally, we compare Cell performance to benchmarks run on leading superscalar (AMD Opteron), VLIW (Intel Itanium2), and vector (Cray X1E) architectures. Our work also explores several different mappings of the kernels and demonstrates a simple and effective programming model for Cell's unique architecture. Finally, we propose modest …
Date: April 4, 2007
Creator: Williams, Samuel W.; Shalf, John; Oliker, Leonid; Kamil, Shoaib; Husbands, Parry & Yelick, Katherine
Object Type: Article
System: The UNT Digital Library
Basic Research Needs for Electrical Energy Storage. Report of the Basic Energy Sciences Workshop on Electrical Energy Storage, April 2-4, 2007 (open access)

Basic Research Needs for Electrical Energy Storage. Report of the Basic Energy Sciences Workshop on Electrical Energy Storage, April 2-4, 2007

To identify research areas in geosciences, such as behavior of multiphase fluid-solid systems on a variety of scales, chemical migration processes in geologic media, characterization of geologic systems, and modeling and simulation of geologic systems, needed for improved energy systems.
Date: April 4, 2007
Creator: Goodenough, J. B.; Abruna, H. D. & Buchanan, M. V.
Object Type: Report
System: The UNT Digital Library
Greensheet (Houston, Tex.), Vol. 38, No. 102, Ed. 1 Wednesday, April 4, 2007 (open access)

Greensheet (Houston, Tex.), Vol. 38, No. 102, Ed. 1 Wednesday, April 4, 2007

Free weekly newspaper that includes business and classified advertising.
Date: April 4, 2007
Creator: unknown
Object Type: Newspaper
System: The Portal to Texas History
Cherokeean Herald (Rusk, Tex.), Vol. 158, No. 6, Ed. 1 Wednesday, April 4, 2007 (open access)

Cherokeean Herald (Rusk, Tex.), Vol. 158, No. 6, Ed. 1 Wednesday, April 4, 2007

Weekly newspaper from Rusk, Texas that includes local, state and national news along with extensive advertising.
Date: April 4, 2007
Creator: Whitehead, Marie
Object Type: Newspaper
System: The Portal to Texas History
North Texas Daily (Denton, Tex.), Vol. 91, No. 73, Ed. 1 Wednesday, April 4, 2007 (open access)

North Texas Daily (Denton, Tex.), Vol. 91, No. 73, Ed. 1 Wednesday, April 4, 2007

Daily student newspaper from the University of North Texas in Denton, Texas that includes local, state and campus news along with advertising.
Date: April 4, 2007
Creator: unknown
Object Type: Newspaper
System: The Portal to Texas History
The University News (Irving, Tex.), Vol. 37, No. 15, Ed. 1 Wednesday, April 4, 2007 (open access)

The University News (Irving, Tex.), Vol. 37, No. 15, Ed. 1 Wednesday, April 4, 2007

Weekly student newspaper from the University of Dallas in Irving, Texas that includes campus news and commentaries along with advertising.
Date: April 4, 2007
Creator: unknown
Object Type: Newspaper
System: The Portal to Texas History
The Rambler (Fort Worth, Tex.), Vol. 98, No. 9, Ed. 1 Wednesday, April 4, 2007 (open access)

The Rambler (Fort Worth, Tex.), Vol. 98, No. 9, Ed. 1 Wednesday, April 4, 2007

Weekly student newspaper from Texas Wesleyan University in Fort Worth, Texas that includes campus and local news along with advertising.
Date: April 4, 2007
Creator: Wylie, Chad
Object Type: Newspaper
System: The Portal to Texas History
Texas Attorney General Opinion: GA-0535 (open access)

Texas Attorney General Opinion: GA-0535

Document issued by the Office of the Attorney General of Texas in Austin, Texas, providing an interpretation of Texas law. It provides the opinion of the Texas Attorney General, Greg Abbott, regarding a legal question submitted for clarification: Whether the trustees of an independent school district must change the terms of office of trustees from three to four years to comply with a statute requiring school districts to conduct joint elections with other political subdivisions (RQ-0538-GA)
Date: April 4, 2007
Creator: Texas. Attorney-General's Office.
Object Type: Text
System: The Portal to Texas History
Nuclear Warheads: The Reliable Replacement Warhead Program and the Life Extension Program (open access)

Nuclear Warheads: The Reliable Replacement Warhead Program and the Life Extension Program

None
Date: April 4, 2007
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Congressional Commissions, Committees, Boards, and Groups: Appointment Authority and Membership (open access)

Congressional Commissions, Committees, Boards, and Groups: Appointment Authority and Membership

This report was intended to inform Members of Congress of their specific appointment responsibilities and to make them aware of their opportunities to serve as members on Congressional Commissions, Committees, Boards, and Groups.
Date: April 4, 2007
Creator: Glassman, Matthew E.
Object Type: Report
System: The UNT Digital Library
Nuclear Weapons: Comprehensive Test Ban Treaty (open access)

Nuclear Weapons: Comprehensive Test Ban Treaty

This report discusses a comprehensive test ban treaty (CTBT). Congress addresses nuclear weapon issues in the annual National Defense Authorization Act and the Energy and Water Development Appropriations Act.
Date: April 4, 2007
Creator: Medalia, Jonathan
Object Type: Report
System: The UNT Digital Library
Ecosystem Restoration in the Great Lakes: The Great Lakes Regional Collaboration Strategy (open access)

Ecosystem Restoration in the Great Lakes: The Great Lakes Regional Collaboration Strategy

This report summarizes the Strategy, analyzes issues related to the Strategy and its implementation, and discusses federal legislation related to restoration in the Great Lake.
Date: April 4, 2007
Creator: Sheikh, Pervaze A.
Object Type: Report
System: The UNT Digital Library
U.S. Trade Policy and the Caribbean: From Trade Preferences to Free Trade Agreements (open access)

U.S. Trade Policy and the Caribbean: From Trade Preferences to Free Trade Agreements

None
Date: April 4, 2007
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Greensheet (Houston, Tex.), Vol. 38, No. 101, Ed. 1 Wednesday, April 4, 2007 (open access)

Greensheet (Houston, Tex.), Vol. 38, No. 101, Ed. 1 Wednesday, April 4, 2007

Free weekly newspaper that includes business and classified advertising.
Date: April 4, 2007
Creator: unknown
Object Type: Newspaper
System: The Portal to Texas History
The Greensheet (Dallas, Tex.), Vol. 30, No. 358, Ed. 1 Wednesday, April 4, 2007 (open access)

The Greensheet (Dallas, Tex.), Vol. 30, No. 358, Ed. 1 Wednesday, April 4, 2007

Free weekly newspaper that includes business and classified advertising.
Date: April 4, 2007
Creator: unknown
Object Type: Newspaper
System: The Portal to Texas History
The importance of EBIT data for Z-pinch plasma diagnostics (open access)

The importance of EBIT data for Z-pinch plasma diagnostics

The results from the last six years of x-ray spectroscopy and spectropolarimetry of high energy density Z-pinch plasmas complemented by experiments with the electron beam ion trap (EBIT) at the Lawrence Livermore National Laboratory (LLNL) are presented. The two topics discussed are the development of M-shell x-ray W spectroscopic diagnostics and K-shell Ti spectropolarimetry of Z-pinch plasmas. The main focus is on radiation from a specific load configuration called an 'X-pinch'. X-pinches are excellent sources for testing new spectral diagnostics and for atomic modelling because of the high density and temperature of the pinch plasmas, which scale from a few {micro}m to several mm in size. They offer a variety of load configurations, which differ in wire connections, number of wires, and wire materials. In this work the study of X-pinches with tungsten wires combined with wires from other, lower-Z materials is reported. Utilizing data produced with the LLNL EBIT at different energies of the electron beam the theoretical prediction of line positions and intensity of M-shell W spectra were tested and calibrated. Polarization-sensitive X-pinch experiments at the University of Nevada, Reno (UNR) provide experimental evidence for the existence of strong electron beams in Ti and Mo X-pinch plasmas and …
Date: April 4, 2007
Creator: Safronova, A S; Kantsyrev, V L; Neill, P; Safronova, U I; Fedin, D A; Ouart, N D et al.
Object Type: Article
System: The UNT Digital Library
ATLAS Metadata Task Force (open access)

ATLAS Metadata Task Force

This document provides an overview of the metadata, which are needed to characterizeATLAS event data at different levels (a complete run, data streams within a run, luminosity blocks within a run, individual events).
Date: April 4, 2007
Creator: Collaboration, ATLAS; Costanzo, D.; Cranshaw, J.; Gadomski, S.; Jezequel, S.; Klimentov, A. et al.
Object Type: Article
System: The UNT Digital Library
Metastable Vacua and D-branes at the Conifold (open access)

Metastable Vacua and D-branes at the Conifold

We consider quiver gauge theories arising on D-branes at simple Calabi-Yau singularities (quotients of the conifold). These theories have metastable supersymmetry breaking vacua. The field theoretic mechanism is basically the one exhibited by the examples of Intriligator, Seiberg and Shih in SUSY QCD. In a dual description, the SUSY breaking is captured by the presence of anti-branes. In comparison to our earlier related work, the main improvements of the present construction are that we can reach the free magnetic range of the SUSY QCD theory where the existence of the metastable vacua is on firm footing, and we can see explicitly how the small masses for the quark flavors (necessary to the existence of the SUSY breaking vacua) are dynamically stabilized. One crucial mass term is generated by a stringy instanton. Finally, our models naturally incorporate R-symmetry breaking in the non-supersymmetric vacuum, in a way similar to the examples of Kitano, Ooguri and Ookouchi.
Date: April 4, 2007
Creator: Argurio, Riccardo; Bertolini, Matteo; Franco, Sebastian & Kachru, Shamit
Object Type: Article
System: The UNT Digital Library
AN OVERVIEW OF CESIUM-137 CONTAMINATION IN A SOUTHEASTERN SWAMP ENVIRONMENT (open access)

AN OVERVIEW OF CESIUM-137 CONTAMINATION IN A SOUTHEASTERN SWAMP ENVIRONMENT

In the early 1960s, an area of privately owned swamp adjacent to the Savannah River Site (SRS) was contaminated by site operations. Studies conducted in 1974 estimated that approximately 925 GBq of {sup 137}Cs and 37 GBq of {sup 60}Co were deposited in the swamp. Subsequently, a series of surveys was initiated to characterize the contaminated environment. These surveys--composed of 52 monitoring locations--allow for continued monitoring at a consistent set of locations. Initial survey results indicated maximum {sup 137}Cs concentrations of 19.5 Bq g{sup -1} in soil and 8.7 Bq g{sup -1} in vegetation. By the 2004-2005 surveys, maximum concentrations had declined to 1-2 Bq g{sup -1} in soil and 0.4 Bq g{sup -1} in vegetation.
Date: April 4, 2007
Creator: Fledderman, P; Tim Jannik, T & Michael Paller, M
Object Type: Article
System: The UNT Digital Library
Sequestering in String Theory (open access)

Sequestering in String Theory

We study sequestering, a prerequisite for flavor-blind supersymmetry breaking in several high-scale mediation mechanisms, in compactifications of type IIB string theory. We find that although sequestering is typically absent in unwarped backgrounds, strongly warped compactifications do readily sequester. The AdS/CFT dual description in terms of conformal sequestering plays an important role in our analysis, and we establish how sequestering works both on the gravity side and on the gauge theory side. We pay special attention to subtle compactification effects that can disrupt sequestering. Our result is a step toward realizing an appealing pattern of soft terms in a KKLT compactification.
Date: April 4, 2007
Creator: Kachru, Shamit; McAllister, Liam & Sundrum, Raman
Object Type: Article
System: The UNT Digital Library
Status of SM Calculations of b to s Transitions (open access)

Status of SM Calculations of b to s Transitions

We report recent progress in SM calculations of b {yields} s transitions. We discuss the first NNLL prediction of the {bar B} {yields} X{sub s}{gamma} branching ratio, including important additional subtleties due to non-perturbative corrections and logarithmically-enhanced cut effects, and also recent results on the inclusive mode {bar B} {yields} X{sub s}{ell}{sup +}{ell}{sup -}. Moreover, new results on the corresponding exclusive modes are reviewed. Finally, we comment on the present status of the so-called B {yields} K{pi} puzzle in hadronic b {yields} s transitions.
Date: April 4, 2007
Creator: Hurth, Tobias & /SLAC, /CERN
Object Type: Report
System: The UNT Digital Library
Storage Ring Optics Measurement, Model, and Correction (open access)

Storage Ring Optics Measurement, Model, and Correction

To improve the optics of a storage ring, it is very helpful if one has an accurate lattice model. Although the ideal lattice may serve such a purpose to some extent, in most cases, real accelerator optics improvement requires accurate measurement of optics parameters. In this section, we present precision measurements of a complete set of linear orbits from which we can form a linear optics model to match the linear optics of the real machine. We call such a model a virtual machine. We have used a model-independent analysis (MIA) for accurate orbit and phase advance measurement and then used an SVD-enhanced Least Square fitting for building accurate virtual models for PEP-II e+, e- storage rings. The MIA virtual machine matches very well the real-machine linear optics including dispersion. It has successfully improved PEP-II beta beats, linear couplings, half-integer working tunes, and dispersion.
Date: April 4, 2007
Creator: Yan, Yiton T.
Object Type: Article
System: The UNT Digital Library