States

Essence of the Vacuum Quark Condensate (open access)

Essence of the Vacuum Quark Condensate

We show that the chiral-limit vacuum quark condensate is qualitatively equivalent to the pseudoscalar meson leptonic decay constant in the sense that they are both obtained as the chiral-limit value of well-defined gauge-invariant hadron-to-vacuum transition amplitudes that possess a spectral representation in terms of the current-quark mass. Thus, whereas it might sometimes be convenient to imagine otherwise, neither is essentially a constant mass-scale that fills all spacetime. This means, in particular, that the quark condensate can be understood as a property of hadrons themselves, which is expressed, for example, in their Bethe-Salpeter or light-front wavefunctions.
Date: August 25, 2010
Creator: Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; Roberts, Craig D.; /Argonne, PHY /Peking U.; Shrock, Robert; /YITP, Stony Brook et al.
Object Type: Article
System: The UNT Digital Library
The AdS/QCD Correspondence and Exclusive Processes (open access)

The AdS/QCD Correspondence and Exclusive Processes

The AdS/CFT correspondence between theories in AdS space and conformal field theories in physical space-time provides an analytic, semi-classical, color-confining model for strongly-coupled QCD. The soft-wall AdS/QCD model modified by a positive-sign dilaton metric leads to a remarkable one-parameter description of nonperturbative hadron dynamics at zero quark mass, including a zero-mass pion and a Regge spectrum of linear trajectories with the same slope in orbital angular momentum L and radial quantum number n for both mesons and baryons. One also predicts the form of the non-perturbative effective coupling {alpha}{sub s}{sup AdS}(q) and its {beta}-function which agrees with the effective coupling {alpha}{sub ga} extracted from the Bjorken sum rule. Light-front holography, which connects the fifth-dimensional coordinate of AdS space z to an invariant impact separation variable {zeta}, allows one to compute the analytic form of the frame-independent light-front wavefunctions, the fundamental entities which encode hadron properties as well as decay constants, form factors, deeply virtual Compton scattering, exclusive heavy hadron decays and other exclusive scattering amplitudes. One thus obtains a relativistic description of hadrons in QCD at the amplitude level with dimensional counting for hard exclusive reactions at high momentum transfer. As specific examples we discuss the behavior of the pion …
Date: August 25, 2010
Creator: Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.; U., /Costa Rica; Deur, Alexandre & Lab, /Jefferson
Object Type: Article
System: The UNT Digital Library
Evaluation of Simple Causal Message Logging for Large-Scale Fault Tolerant HPC Systems (open access)

Evaluation of Simple Causal Message Logging for Large-Scale Fault Tolerant HPC Systems

The era of petascale computing brought machines with hundreds of thousands of processors. The next generation of exascale supercomputers will make available clusters with millions of processors. In those machines, mean time between failures will range from a few minutes to few tens of minutes, making the crash of a processor the common case, instead of a rarity. Parallel applications running on those large machines will need to simultaneously survive crashes and maintain high productivity. To achieve that, fault tolerance techniques will have to go beyond checkpoint/restart, which requires all processors to roll back in case of a failure. Incorporating some form of message logging will provide a framework where only a subset of processors are rolled back after a crash. In this paper, we discuss why a simple causal message logging protocol seems a promising alternative to provide fault tolerance in large supercomputers. As opposed to pessimistic message logging, it has low latency overhead, especially in collective communication operations. Besides, it saves messages when more than one thread is running per processor. Finally, we demonstrate that a simple causal message logging protocol has a faster recovery and a low performance penalty when compared to checkpoint/restart. Running NAS Parallel Benchmarks …
Date: February 25, 2011
Creator: Bronevetsky, G.; Meneses, E. & Kale, L. V.
Object Type: Article
System: The UNT Digital Library
Improved Superconducting Wire for Wind Generators (open access)

Improved Superconducting Wire for Wind Generators

Advanced Research Projects Agency-Energy project sheet summarizing general information about the Rare Earth Alternatives in Critical Technologies (REACT) program including critical needs, innovation and advantages, impacts, and contact information. This sheet discusses a new superconducting wire as part of the "Superconducting Wires for Direct-Drive Wind Generators" project.
Date: May 25, 2012
Creator: Brookhaven National Laboratory
Object Type: Text
System: The UNT Digital Library
MPO B593110 - Final Report (open access)

MPO B593110 - Final Report

National Security Technologies, LLC (NSTec) shall provide one (1) Mechanical Engineer to support the Linear Collider Subsystem Development Program at Lawrence Livermore National Security, LLC (LLNS). The NSTec Mechanical Engineer's efforts will include engineering, design, and drawing support for the Vacuum Seal Test. NSTec will also provide a final report of the setup and input to LLNL's project management on project status. The NSTec Mechanical Engineer's efforts will also include engineering, design, and drawing support to the conceptual design for manufacturing of the Flux Concentrator Magnet. NSTec will also contribute to LLNS's final report on the Flux Concentrator Magnet. The deliverables are drawings, sketches, engineering documents, and final reports delivered to the LLNS Technical Representative.
Date: July 25, 2011
Creator: Brooksby, C
Object Type: Report
System: The UNT Digital Library
Overview of the 2009 Release of the Evaluated Nuclear Data Library (endl2009) (open access)

Overview of the 2009 Release of the Evaluated Nuclear Data Library (endl2009)

The Lawrence Livermore National Laboratory (LLNL) Physics Division has produced the next iteration of LLNL's evaluated nuclear database, ENDL2009. ENDL2009 is the second in a series of major ENDL library releases designed to support LLNL's current and future nuclear data needs. This library includes 585 distinct transport-ready evaluations in the neutron sub-library and many physics improvements for stockpile stewardship, attribution signatures, key radiochemical diagnostics and performance of conventional and hybrid fission/fusion reactors. In building this library, we adopted the best of the world's nuclear data efforts: 46% of the library is from the ENDF/B-VII.0 library, 10% is from the JENDL libraries and 8% from other libraries. The remaining 36% of the neutron sub-library and all of the charged-particle sub-libraries consist of new evaluations developed at LLNL for the ENDL2009 library. In addition, ENDL2009 supports new features such as energy-dependent Q values from fission, support for unresolved resonances and average momentum deposition. Finally, this release is our most highly tested release as we have strengthened our already rigorous testing regime by adding tests against LANL Activation Ratio Measurements and more than 1200 new critical assemblies. Our testing is now being incorporated into our development process and is serving to guide database …
Date: April 25, 2010
Creator: Brown, D. A.; Beck, B.; Descalle, M.; Hoffman, R.; Ormand, E.; Navratil, P. et al.
Object Type: Article
System: The UNT Digital Library
Economic Impacts of Wind Turbine Development in U.S. Counties (open access)

Economic Impacts of Wind Turbine Development in U.S. Counties

The objective is to address the research question using post-project construction, county-level data, and econometric evaluation methods. Wind energy is expanding rapidly in the United States: Over the last 4 years, wind power has contributed approximately 35 percent of all new electric power capacity. Wind power plants are often developed in rural areas where local economic development impacts from the installation are projected, including land lease and property tax payments and employment growth during plant construction and operation. Wind energy represented 2.3 percent of the U.S. electricity supply in 2010, but studies show that penetrations of at least 20 percent are feasible. Several studies have used input-output models to predict direct, indirect, and induced economic development impacts. These analyses have often been completed prior to project construction. Available studies have not yet investigated the economic development impacts of wind development at the county level using post-construction econometric evaluation methods. Analysis of county-level impacts is limited. However, previous county-level analyses have estimated operation-period employment at 0.2 to 0.6 jobs per megawatt (MW) of power installed and earnings at $9,000/MW to $50,000/MW. We find statistically significant evidence of positive impacts of wind development on county-level per capita income from the OLS and …
Date: July 25, 2011
Creator: Brown, J.; Hoen, B.; Lantz, E.; Pender, J. & Wiser, R.
Object Type: Article
System: The UNT Digital Library
Progress in Developing the STFNSF Configuration (open access)

Progress in Developing the STFNSF Configuration

The design features developed for the Spherical Tokamak (ST) in the PPPL pilot plant study was used as the starting point in developing designs to meet the mission of a Fusion Nuclear Science Facility (FNSF) considering a range of machine sizes based on the influence of tritium consumption and maintenance strategies. The compact nature of a steady state operated ST device for this mission pushes operating conditions and places challenges in the design of components, device maintenance and the integration of supports and services. This paper reviews the general arrangement, design details and maintenance strategy of the ST-FNSF device core for a 1.6-m and 1.0-m device; operating points which bracket the region between purchasing and breeding tritium.
Date: June 25, 2013
Creator: Brown, Thomas
Object Type: Article
System: The UNT Digital Library
TP66-MicroCT Small Volume Comparison (open access)

TP66-MicroCT Small Volume Comparison

None
Date: January 25, 2013
Creator: Brown, W D & Martz, H E
Object Type: Report
System: The UNT Digital Library
TP75-MicroCT Test Bed Data Acquisition for Multi-Energy Zeff and Rho-e Decomposition Analysis (open access)

TP75-MicroCT Test Bed Data Acquisition for Multi-Energy Zeff and Rho-e Decomposition Analysis

None
Date: January 25, 2013
Creator: Brown, W. D. & Smith, J. A.
Object Type: Report
System: The UNT Digital Library
Radiocarbon Dating (open access)

Radiocarbon Dating

Abstract: Radiocarbon dating can be used to determine the age of objects that contain components that were once alive. In the case of human remains, a radiocarbon date can distinguish between a crime scene and an archaeological site. Documents, museum artifacts and art objects can be dated to determine if their age is correct for the historical context. A radiocarbon date does not confirm authenticity, but it can help identify a forgery.
Date: May 25, 2012
Creator: Buchholz, Bruce A.
Object Type: Book Chapter
System: The UNT Digital Library
Simulation of radio emission from air showers in atmospheric electric fields (open access)

Simulation of radio emission from air showers in atmospheric electric fields

We study the effect of atmospheric electric fields on the radio pulse emitted by cos- mic ray air showers. Under fair weather conditions the dominant part of the radio emission is driven by the geomagnetic field. When the shower charges are accelerated and deflected in an electric field additional radiation is emitted. We simulate this effect with the Monte Carlo code REAS2, using CORSIKA-simulated showers as input. In both codes a routine has been implemented that treats the effect of the electric field on the shower particles. We find that the radio pulse is significantly altered in background fields of the order of ~100 V/cm and higher. Practically, this means that air showers passing through thunderstorms emit radio pulses that are not a reliable measure for the shower energy. Under other weather circumstances significant electric field effects are expected to occur rarely, but nimbostratus clouds can harbor fields that are large enough. In general, the contribution of the electric field to the radio pulse has polarization properties that are different from the geomagnetic pulse. In order to filter out radio pulses that have been affected by electric field effects, radio air shower experiments should keep weatherinformation and perform full polarization …
Date: February 25, 2010
Creator: Buitink, S.; Huege, T.; Falcke, H & Kuijpers, J.
Object Type: Article
System: The UNT Digital Library
What Coexists with the Ferromagnetic Metallic Phase in Manganites? (open access)

What Coexists with the Ferromagnetic Metallic Phase in Manganites?

Colossal magnetoresistance, whereby the application of a magnetic field reduces the resistivity of a manganite by orders of magnitude, is generally believed to occur because of coexisting phases. Development of a complete theory to explain the phenomenon requires that the exact nature of these phases be known. We used resonant elastic soft x-ray scattering to examine the superlattice order that exists in La{sub 0.35}Pr{sub 0.275}Ca{sub 0.375}MnO{sub 3} above and below the Curie temperature. By measuring the resonance profile of the scattered x-rays at different values of q, we disentangle the contributions of orbital order and antiferromagnetism to the scattering signal above the Curie temperature. Below the Curie temperature, we see no signal from orbital order, and only antiferromagnetism coexists with the dominant ferromagnetic metallic phase.
Date: July 25, 2012
Creator: Burkhardt, Mark H.; Hossain, M.A.; Sarkar, S.; Achkar, A.J.; Hawthorn, D.G.; Sutarto, R. et al.
Object Type: Article
System: The UNT Digital Library
ILC Marx Modulator Development Program Status (open access)

ILC Marx Modulator Development Program Status

A Marx-topology klystron modulator is under development for the International Linear Collider (ILC) project. It is envisioned as a lower cost, smaller footprint, and higher reliability alternative to the present, bouncer-topology, baseline design. The application requires 120 kV (+/-0.5%), 140 A, 1.6 ms pulses at a rate of 5 Hz. The Marx constructs the high voltage pulse by combining, in series, a number of lower voltage cells. The Marx employs solid state elements; IGBTs and diodes, to control the charge, discharge and disolation of the cells. Active compensation of the output is used to achieve the voltage regulation while minimizing the stored energy. The developmental testing of a first generation prototype, P1, has been completed. This modulator has been integrated into a test stand with a 10 MW L-band klystron, where each is undergoing life testing. Development of a second generation prototype, P2, is underway. The P2 is based on the P1 topology but incorporates an alternative cell configuration to increase redundancy and improve availability. Status updates for both prototypes are presented.
Date: August 25, 2010
Creator: Burkhart, Craig; Benwell, Andrew; Beukers, Tony; Kemp, Mark; Larsen, Raymond; MacNair, David et al.
Object Type: Article
System: The UNT Digital Library
EVALUATION OF ALTERNATIVE STRONIUM AND TRANSURANIC SEPARATION PROCESSES (open access)

EVALUATION OF ALTERNATIVE STRONIUM AND TRANSURANIC SEPARATION PROCESSES

In order to meet contract requirements on the concentrations of strontium-90 and transuranic isotopes in the immobilized low-activity waste, strontium-90 and transuranics must be removed from the supernate of tanks 241-AN-102 and 241-AN-107. The process currently proposed for this application is an in-tank precipitation process using strontium nitrate and sodium permanganate. Development work on the process has not proceeded since 2005. The purpose of the evaluation is to identify whether any promising alternative processes have been developed since this issue was last examined, evaluate the alternatives and the baseline process, and recommend which process should be carried forward.
Date: April 25, 2011
Creator: CS, SMALLEY
Object Type: Report
System: The UNT Digital Library
Clearwater and Wineskin Sub-CAU Flow and Transport Models (open access)

Clearwater and Wineskin Sub-CAU Flow and Transport Models

None
Date: July 25, 2012
Creator: Carle, S F
Object Type: Report
System: The UNT Digital Library
Rare Plant Monitoring and Restoration at the Lawrence Livermore National Laboratory Experimental Test Site, Site 300, Project Progress Report 2007 through 2011 (open access)

Rare Plant Monitoring and Restoration at the Lawrence Livermore National Laboratory Experimental Test Site, Site 300, Project Progress Report 2007 through 2011

None
Date: September 25, 2012
Creator: Carlsen, T M; Paterson, L E; Alfaro, T M & Gregory, S D
Object Type: Report
System: The UNT Digital Library
Optical System Case Studies for Speckle Imaging (open access)

Optical System Case Studies for Speckle Imaging

None
Date: October 25, 2013
Creator: Carrano, C J
Object Type: Report
System: The UNT Digital Library
A Comparison of "Total Dust" and Inhalable Personal Sampling for Beryllium Exposure. (open access)

A Comparison of "Total Dust" and Inhalable Personal Sampling for Beryllium Exposure.

In 2009, the American Conference of Governmental Industrial Hygienists (ACGIH) reduced the Beryllium (Be) 8-hr Time Weighted Average Threshold Limit Value (TLV-TWA) from 2.0 {micro}g/m{sup 3} to 0.05 {micro}g/m{sup 3} with an inhalable 'I' designation in accordance with ACGIH's particle size-selective criterion for inhalable mass. Currently, per the Department of Energy (DOE) requirements, the Lawrence Livermore National Laboratory (LLNL) is following the Occupational Health and Safety Administration (OSHA) Permissible Exposure Limit (PEL) of 2.0 {micro}g/m{sup 3} as an 8-hr TWA, which is also the 2005 ACGIH TLV-TWA, and an Action Level (AL) of 0.2 {micro}g/m{sup 3} and sampling is performed using the 37mm (total dust) sampling method. Since DOE is considering adopting the newer 2009 TLV guidelines, the goal of this study was to determine if the current method of sampling using the 37mm (total dust) sampler would produce results that are comparable to what would be measured using the IOM (inhalable) sampler specific to the application of high energy explosive work at LLNL's remote experimental test facility at Site 300. Side-by-side personal sampling using the two samplers was performed over an approximately two-week period during chamber re-entry and cleanup procedures following detonation of an explosive assembly containing Beryllium (Be). …
Date: April 25, 2012
Creator: Carter, C. M.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Iron-Nitride Alloy Magnets (open access)

Iron-Nitride Alloy Magnets

Advanced Research Projects Agency-Energy project sheet summarizing general information about the Rare Earth Alternatives in Critical Technologies (REACT) program including critical needs, innovation and advantages, impacts, and contact information. This sheet discusses the development of a magnetic iron-nitride alloy as part of the "Transformation Enabled Nitride Magnets Absent Rare Earths (TEN Mare)" project.
Date: May 25, 2012
Creator: Case Western Reserve University
Object Type: Text
System: The UNT Digital Library
Shot Planning and Analysis Tools (open access)

Shot Planning and Analysis Tools

Shot planning and analysis tools (SPLAT) integrate components necessary to help achieve a high over-all operational efficiency of the National Ignition Facility (NIF) by combining near and long-term shot planning, final optics demand and supply loops, target diagnostics planning, and target fabrication requirements. Currently, the SPLAT project is comprised of two primary tool suites for shot planning and optics demand. The shot planning component provides a web-based interface to selecting and building a sequence of proposed shots for the NIF. These shot sequences, or 'lanes' as they are referred to by shot planners, provide for planning both near-term shots in the Facility and long-term 'campaigns' in the months and years to come. The shot planning capabilities integrate with the Configuration Management Tool (CMT) for experiment details and the NIF calendar for availability. Future enhancements will additionally integrate with target diagnostics planning and target fabrication requirements tools. The optics demand component is built upon predictive modelling of maintenance requirements on the final optics as a result of the proposed shots assembled during shot planning. The predictive models integrate energetics from a Laser Performance Operations Model (LPOM), the status of the deployed optics as provided by the online Final Optics Inspection system, …
Date: July 25, 2011
Creator: Casey, A.; Beeler, R.; Conder, A.; Fallejo, R.; Flegel, M.; Hutton, M. et al.
Object Type: Article
System: The UNT Digital Library
SRS SLUDGE BATCH QUALIFICATION AND PROCESSING; HISTORICAL PERSPECTIVE AND LESSONS LEARNED (open access)

SRS SLUDGE BATCH QUALIFICATION AND PROCESSING; HISTORICAL PERSPECTIVE AND LESSONS LEARNED

This report provides a historical overview and lessons learned associated with the SRS sludge batch (SB) qualification and processing programs. The report covers the framework of the requirements for waste form acceptance, the DWPF Glass Product Control Program (GPCP), waste feed acceptance, examples of how the program complies with the specifications, an overview of the Startup Program, and a summary of continuous improvements and lessons learned. The report includes a bibliography of previous reports and briefings on the topic.
Date: September 25, 2013
Creator: Cercy, M.; Peeler, D. & Stone, M.
Object Type: Report
System: The UNT Digital Library
Activation Energy of Tantalum-Tungsten Oxide Thermite Reaction (open access)

Activation Energy of Tantalum-Tungsten Oxide Thermite Reaction

The activation energy of a high melting temperature sol-gel (SG) derived tantalum-tungsten oxide thermite composite was determined using the Kissinger isoconversion method. The SG derived powder was consolidated using the High Pressure Spark Plasma Sintering (HPSPS) technique to 300 and 400 C to produce pellets with dimensions of 5 mm diameter by 1.5 mm height. A custom built ignition setup was developed to measure ignition temperatures at high heating rates (500-2000 C {center_dot} min{sup -1}). Such heating rates were required in order to ignite the thermite composite. Unlike the 400 C samples, results show that the samples consolidated to 300 C undergo an abrupt change in temperature response prior to ignition. This change in temperature response has been attributed to the crystallization of the amorphous WO{sub 3} in the SG derived Ta-WO{sub 3} thermite composite and not to a pre-ignition reaction between the constituents. Ignition temperatures for the Ta-WO{sub 3} thermite ranged from approximately 465-670 C. The activation energy of the SG derived Ta-WO{sup 3} thermite composite consolidated to 300 and 400 C were determined to be 37.787 {+-} 1.58 kJ {center_dot} mol{sup -1} and 57.381 {+-} 2.26 kJ {center_dot} mol{sup -1}, respectively.
Date: February 25, 2010
Creator: Cervantes, O.; Kuntz, J.; Gash, A. & Munir, Z.
Object Type: Article
System: The UNT Digital Library
TP76 -MicroCT Scatter Evaluation (open access)

TP76 -MicroCT Scatter Evaluation

None
Date: January 25, 2013
Creator: Champley, K
Object Type: Report
System: The UNT Digital Library