Experimental astrophysics with high power lasers and Z pinches (open access)

Experimental astrophysics with high power lasers and Z pinches

With the advent of high energy density (HED) experimental facilities, such as high-energy lasers and fast Z-pinch, pulsed-power facilities, mm-scale quantities of matter can be placed in extreme states of density, temperature, and/or velocity. This has enabled the emergence of a new class of experimental science, HED laboratory astrophysics, wherein the properties of matter and the processes that occur under extreme astrophysical conditions can be examined in the laboratory. Areas particularly suitable to this class of experimental astrophysics include the study of opacities relevant to stellar interiors; equations of state relevant to planetary interiors; strong shock driven nonlinear hydrodynamics and radiative dynamics, relevant to supernova explosions and subsequent evolution; protostellar jets and high Mach-number flows; radiatively driven molecular clouds and nonlinear photoevaporation front dynamics; and photoionized plasmas relevant to accretion disks around compact objects, such as black holes and neutron stars.
Date: December 10, 2004
Creator: Remington, B. A.; Drake, R. P. & Ryutov, D. D.
Object Type: Article
System: The UNT Digital Library
Effects of polar solvents on the fracture resistance of dentin: Role of water hydration (open access)

Effects of polar solvents on the fracture resistance of dentin: Role of water hydration

Although healthy dentin is invariably hydrated in vivo, from a perspective of examining the mechanisms of fracture in dentin, it is interesting to consider the role of water hydration. Furthermore, it is feasible that exposure to certain polar solvents, e.g., those found in clinical adhesives, can induce dehydration. In the present study, in vitro deformation and fracture experiments, the latter involving a resistance-curve (R-curve) approach (i.e., toughness evolution with crack extension), were conducted in order to assess changes in the constitutive and fracture behavior induced by three common solvents - acetone, ethanol and methanol. In addition, nanoindentation-based experiments to evaluate the deformation behavior at the level of individual collagen fibers and ultraviolet Raman spectroscopy to evaluate changes in bonding were performed. The results indicate a reversible effect of chemical dehydration, with increased fracture resistance, strength, and stiffness associated with lower hydrogen bonding ability of the solvent. These results are analyzed both in terms of intrinsic and extrinsic toughening phenomena to further understand the micromechanisms of fracture in dentin and the specific role of water hydration.
Date: December 10, 2004
Creator: Ritchie, R. O.; Nalla, R. K.; Balooch, M.; Ager, J. W., III; Kruzic, J. J. & Kinney, J. H.
Object Type: Article
System: The UNT Digital Library
First tests of a Micromegas TPC in a magnetic field (open access)

First tests of a Micromegas TPC in a magnetic field

Since the summer of 2003, a large Micromegas TPC prototype (1000 channels, 50 cm drift, 50 cm diameter) has been operated in a 2T superconducting magnet at Saclay. A description of this apparatus and first results from cosmic ray tests are presented. Additional measurements using simpler detectors with a laser source, an X-ray gun and radio-active sources are discussed. Drift velocity and gain measurements, electron attachment and aging studies for a Micromegas TPC are presented. In particular, using simulations and measurements, it is shown that an $Argon-CF_4$ mixture is optimal for operation at a future Linear Collider.
Date: December 10, 2004
Creator: Colas, P.; Giomataris, I.; Lepeltier, V. & Ronan, M.
Object Type: Article
System: The UNT Digital Library
GEOGRAPHIC INFORMATION SYSTEM APPROACH FOR PLAY PORTFOLIOS TO IMPROVE OIL PRODUCTION IN THE ILLINOIS BASIN (open access)

GEOGRAPHIC INFORMATION SYSTEM APPROACH FOR PLAY PORTFOLIOS TO IMPROVE OIL PRODUCTION IN THE ILLINOIS BASIN

Oil and gas have been commercially produced in Illinois for over 100 years. Existing commercial production is from more than fifty-two named pay horizons in Paleozoic rocks ranging in age from Middle Ordovician to Pennsylvanian. Over 3.2 billion barrels of oil have been produced. Recent calculations indicate that remaining mobile resources in the Illinois Basin may be on the order of several billion barrels. Thus, large quantities of oil, potentially recoverable using current technology, remain in Illinois oil fields despite a century of development. Many opportunities for increased production may have been missed due to complex development histories, multiple stacked pays, and commingled production which makes thorough exploitation of pays and the application of secondary or improved/enhanced recovery strategies difficult. Access to data, and the techniques required to evaluate and manage large amounts of diverse data are major barriers to increased production of critical reserves in the Illinois Basin. These constraints are being alleviated by the development of a database access system using a Geographic Information System (GIS) approach for evaluation and identification of underdeveloped pays. The Illinois State Geological Survey has developed a methodology that is being used by industry to identify underdeveloped areas (UDAs) in and around petroleum …
Date: December 10, 2004
Creator: Seyler, Beverly & Grube, John
Object Type: Report
System: The UNT Digital Library
Identification of Non-Pertechnetate Species In Hanford Tank Waste, Their Synthesis, Characterization, And Fundamental Chemistry (open access)

Identification of Non-Pertechnetate Species In Hanford Tank Waste, Their Synthesis, Characterization, And Fundamental Chemistry

This proposal had three major goals: (1) develop capillary electrophoresis mass spectrometry as a characterization technique, (2) separate a non-pertechnetate fraction from a waste sample and identify the non-pertechnetate species in it by CEMS, and (3) synthesize and characterize bulk quantities of the identified non-pertechnetate species and study their ligand substitution and redox chemistry.
Date: December 10, 2004
Creator: Ashely, Kenneth R.; Schroeder, Norman; Olivares, Jose A. & Scott, Brian
Object Type: Report
System: The UNT Digital Library
81891 - A New Class of Solvents for TRU Dissolution and Separation: Ionic Liquids (open access)

81891 - A New Class of Solvents for TRU Dissolution and Separation: Ionic Liquids

Through the current EMSP funding, solvent extraction technologies based on liquid-liquid partitioning of TRU to an Ionic Liquid phase containing conventional complexants has been shown to be viable. The growing understanding of the role that the different components of an ionic liquid can have on the partitioning mechanism, and on the nature of the subsequent dissolved species indicates strongly that ionic liquids are not necessarily direct replacements for volatile or otherwise hazardous organic solvents. Separations and partitioning can be exceptionally complex with competing solvent extraction, cation, anion and sacrificial ion exchange mechanisms are all important, depending on the selection of components for formation of the ionic liquid phase, and that control of these competing mechanisms can be utilized to provide new, alternative separations schemes.
Date: December 10, 2004
Creator: Rogers, Robin D.
Object Type: Report
System: The UNT Digital Library
Managing Tight Binding Receptors for New Spearations Technologies (open access)

Managing Tight Binding Receptors for New Spearations Technologies

Much of the earth's pollution involves compounds of the metallic elements, including actinides, strontium, cesium, technetium, and RCRA metals. Metal ions bind to molecules called ligands, which are the molecular tools that can manipulate the metal ions under most conditions. This DOE-EMSP sponsored program strives (1) to provide the foundations for using the most powerful ligands in transformational separations technologies and (2) to produce seminal examples of their applications to separations appropriate to the DOE EM mission. These ultra tight-binding ligands can capture metal ions in the most competitive of circumstances (from mineralized sites, lesser ligands, and even extremely dilute solutions), but they react so slowly that they are useless in traditional separations methodologies. Two attacks on this problem are underway. The first accommodates to the challenging molecular lethargy by developing a seminal slow separations methodology termed the soil poultice. The second designs ligands that are only tight-binding while wrapped around the targeted metal ion, but can be put in place by switch-binding and removed by switch-release. We envision a kind of molecular switching process to accelerate the union between metal ion and tight-binding ligand. Molecular switching processes are suggested for overcoming the slow natural equilibration rate with which ultra …
Date: December 10, 2004
Creator: Busch, Daryle H.
Object Type: Report
System: The UNT Digital Library
YUMMY: The Yucca Mountain MCNP-Library (open access)

YUMMY: The Yucca Mountain MCNP-Library

Point-wise libraries provided with the MCNP code contain neutron data for a limited number of temperatures. However, it is important to have the option of using data from a wide range of temperatures for transport calculations. For this purpose, a multi-temperature, ACE-format neutron library was generated for 134 nuclides, as requested by Yucca Mountain Project (YMP) staff. The library is referred to as YUMMY (YUcca Mountain MCNP-librarY). The neutron cross section data are based on ENDF/B-V or ENDF/B-VI evaluations that were requested by YMP staff. This document provides the details of the new library and its use in criticality safety benchmark problems, a Pressurized Water Reactor design and waste package models in MCNP4C.
Date: December 10, 2004
Creator: Alpan, FA
Object Type: Report
System: The UNT Digital Library
Final Technical Report EMSP 70045 Investigation of Pore Scale Processes That Affect Soil Vapor Extraction (open access)

Final Technical Report EMSP 70045 Investigation of Pore Scale Processes That Affect Soil Vapor Extraction

Dense nonaqueous phase liquid (DNAPL) contamination in the vadose zone is a significant problem at Department of Energy sites. Soil vapor extraction (SVE) is commonly used to remediate DNAPLs from the vadose zone. In most cases, a period of high recovery has been followed by a sustained period of low recovery. This behavior has been attributed to multiple processes including slow interphase mass transfer, retarded vapor phase transport, and diffusion from unswept zones of low permeability. This research project used a combination of laboratory experimentation and mathematical modeling to determine how these various processes interact to limit the removal of DNAPL components in heterogeneous porous media during SVE. Our results were applied to scenarios typical of the carbon tetrachloride spill zone at the Hanford Site. Our results indicate that: (a) the initial distribution of the spilled DNAPL (i.e., the spill-zone architecture) has a major influence upon the performance of any subsequent SVE operations; (b) while the pattern of higher and lower conductivity soil zones has an important impact upon spill zone architecture, soil moisture distribution plays an even larger role when there are large quantities of co-disposed waste-water (as in the Hanford scenario); (c) depending upon soil moisture dynamics, liquid …
Date: December 10, 2004
Creator: Valocchi, Albert J.; Werth, Charles W. & Webb, Andrew W.
Object Type: Report
System: The UNT Digital Library
Direct observation of surface ethyl to ethane interconversion uponC2H4 hydrogenation over Pt/Al2O3 catalyst by time-resolved FT-IRspectroscopy (open access)

Direct observation of surface ethyl to ethane interconversion uponC2H4 hydrogenation over Pt/Al2O3 catalyst by time-resolved FT-IRspectroscopy

Time-resolved FT-IR spectra of ethylene hydrogenation over alumina-supported Pt catalyst were recorded at 25 ms resolution in the temperature range 323 to 473 K using various H2 flow rates (1 atm total gas pressure). Surface ethyl species (2870 and 1200 cm-1) were detected at all temperatures along with the gas phase ethane product (2954 and 2893 cm-1). The CH3CH2Pt growth was instantaneous on the time scale of 25ms under all experimental conditions. At 323 K, the decay time of surface ethyl (122 + 10 ms) coincides with the rise time of C2H6 (144 + 14 ms).This establishes direct kinetic evidence for surface ethyl as the kinetically relevant intermediate. Such a direct link between the temporal behavior of an observed intermediate and the final product growth in a heterogeneous catalytic system has not been demonstrated before to our knowledge. A fraction (10 percent) of the asymptotic ethane growth at 323 K is prompt, indicating that there are surface ethyl species that react much faster than the majority of the CH3CH2Pt intermediates. The dispersive kinetics is attributed to the varying strength of interaction of the ethyl species with the Pt surface caused by heterogeneity of the surface environment. At 473 K, the …
Date: December 10, 2004
Creator: Wasylenko, Walter & Frei, Heinz
Object Type: Article
System: The UNT Digital Library
Guiding of relativistic laser pulses by preformed plasmachannels (open access)

Guiding of relativistic laser pulses by preformed plasmachannels

Guiding of relativistically intense (>1018 W/cm2) laser pulses over more than 10 diffraction lengths has been demonstrated using plasma channels formed by hydrodynamic shock. Pulses up to twice the self guiding threshold power were guided without aberration by tuning the guide profile. Transmitted spectra and mode images showed the pulse remained in the channel over the entire length. Experiments varying guided mode power and simulations show a large plasma wave was driven.Operating just below the trapping threshold produces a dark current free structure suitable for controlled injection.
Date: December 10, 2004
Creator: Geddes, C. G. R.; Toth, Cs.; van Tilborg, J.; Esarey, E.; Schroeder, C. B.; Cary, J. et al.
Object Type: Article
System: The UNT Digital Library
Verification and Validation using DAKOTA via the DakTools scripts (open access)

Verification and Validation using DAKOTA via the DakTools scripts

Several of the intermediate capabilities which are being developed by the AX V&V program may be helpful in other ways. This paper describes a new PYTHON interface to one such tool, DAKOTA (a parallel optimizing controller from Sandia National Laboratory) and the subsequent simpler set of operations required to run and analyze sets of calculations using any LCC computational platform.
Date: December 10, 2004
Creator: Brandon, S & Tipton, P
Object Type: Article
System: The UNT Digital Library
Performance Evaluation of Industrial Hygiene Air Monitoring Sensors (open access)

Performance Evaluation of Industrial Hygiene Air Monitoring Sensors

Tests were performed to evaluate the accuracy, precision and response time of certain commercially available handheld toxic gas monitors. The tests were conducted by PNNL in the Chemical Chamber Test Facility for CH2MHill Hanford Company. The instruments were tested with a set of dilute test gases including ammonia, nitrous oxide, and a mixture of organic vapors (acetone, benzene, ethanol, hexane, toluene and xylene). The certified gases were diluted to concentrations that may be encountered in the outdoor environment above the underground tank farms containing radioactive waste at the U.S. Department of Energy's Hanford site, near Richland, Washington. The challenge concentrations are near the lower limits of instrument sensitivity and response time. The performance test simulations were designed to look at how the instruments respond to changes in test gas concentrations that are similar to field conditions.
Date: December 10, 2004
Creator: Maughan, A D.; Glissmeyer, John A. & Birnbaum, Jerome C.
Object Type: Report
System: The UNT Digital Library
Comparing Shape and Texture Features for Pattern Recognition in Simulation Data (open access)

Comparing Shape and Texture Features for Pattern Recognition in Simulation Data

Shape and texture features have been used for some time for pattern recognition in datasets such as remote sensed imagery, medical imagery, photographs, etc. In this paper, we investigate shape and texture features for pattern recognition in simulation data. In particular, we explore which features are suitable for characterizing regions of interest in images resulting from fluid mixing simulations. Three texture features--gray level co-occurrence matrices, wavelets, and Gabor filters--and two shape features--geometric moments and the angular radial transform--are compared. The features are evaluated using a similarity retrieval framework. Our preliminary results indicate that Gabor filters perform the best among the texture features and the angular radial transform performs the best among the shape features. The feature which performs the best overall is dependent on how the groundtruth dataset is created.
Date: December 10, 2004
Creator: Newsam, S & Kamath, C
Object Type: Article
System: The UNT Digital Library
Effect of Multi-Shot X-Ray Exposures in IFE Armor Materials (open access)

Effect of Multi-Shot X-Ray Exposures in IFE Armor Materials

As part of the High Average Power Laser (HAPL) program the performance of tungsten as an armor material is being studied. While the armor would be exposed to neutrons, x-rays and ions within an inertial fusion energy (IFE) power plant, the thermomechanical effects are believed to dominate. Using a pulsed x-ray source, long-term exposures of tungsten have been completed at fluences that are of interest for the IFE application. Modeling is used in conjunction with experiments on the XAPPER x-ray damage facility in an effort to recreate the effects that would be expected in an operating IFE power plant. X-ray exposures have been completed for a variety of x-ray fluences and number of shots. Analysis of the samples suggests that surface roughening has a threshold that is very close to the fluences that reproduce the peak temperatures expected in an IFE armor material.
Date: December 10, 2004
Creator: Latkowski, J. F.; Abbott, R. P.; Schmitt, R. C. & Bell, B. K.
Object Type: Article
System: The UNT Digital Library
Real-Time Water Quality Management in the Grassland Water District (open access)

Real-Time Water Quality Management in the Grassland Water District

The purpose of the research project was to advance the concept of real-time water quality management in the San Joaquin Basin by developing an application to drainage of seasonal wetlands in the Grassland Water District. Real-time water quality management is defined as the coordination of reservoir releases, return flows and river diversions to improve water quality conditions in the San Joaquin River and ensure compliance with State water quality objectives. Real-time water quality management is achieved through information exchange and cooperation between shakeholders who contribute or withdraw flow and salt load to or from the San Joaquin River. This project complements a larger scale project that was undertaken by members of the Water Quality Subcommittee of the San Joaquin River Management Program (SJRMP) and which produced forecasts of flow, salt load and San Joaquin River assimilative capacity between 1999 and 2003. These forecasts can help those entities exporting salt load to the River to develop salt load targets as a mechanism for improving compliance with salinity objectives. The mass balance model developed by this project is the decision support tool that helps to establish these salt load targets. A second important outcome of this project was the development and application …
Date: December 10, 2004
Creator: Quinn, Nigel W.T.; Hanna, W. Mark; Hanlon, Jeremy S.; Burns, Josphine R.; Taylor, Christophe M.; Marciochi, Don et al.
Object Type: Report
System: The UNT Digital Library