EM-31 RETRIEVAL KNOWLEDGE CENTER MEETING REPORT: MOBILIZE AND DISLODGE TANK WASTE HEELS (open access)

EM-31 RETRIEVAL KNOWLEDGE CENTER MEETING REPORT: MOBILIZE AND DISLODGE TANK WASTE HEELS

The Retrieval Knowledge Center sponsored a meeting in June 2009 to review challenges and gaps to retrieval of tank waste heels. The facilitated meeting was held at the Savannah River Research Campus with personnel broadly representing tank waste retrieval knowledge at Hanford, Savannah River, Idaho, and Oak Ridge. This document captures the results of this meeting. In summary, it was agreed that the challenges to retrieval of tank waste heels fell into two broad categories: (1) mechanical heel waste retrieval methodologies and equipment and (2) understanding and manipulating the heel waste (physical, radiological, and chemical characteristics) to support retrieval options and subsequent processing. Recent successes and lessons from deployments of the Sand and Salt Mantis vehicles as well as retrieval of C-Area tanks at Hanford were reviewed. Suggestions to address existing retrieval approaches that utilize a limited set of tools and techniques are included in this report. The meeting found that there had been very little effort to improve or integrate the multiple proven or new techniques and tools available into a menu of available methods for rapid insertion into baselines. It is recommended that focused developmental efforts continue in the two areas underway (low-level mixing evaluation and pumping slurries …
Date: February 16, 2010
Creator: Fellinger, A.
Object Type: Report
System: The UNT Digital Library
EVALUATION OF TROQUE VS CLOSURE BOLT PRELOAD FOR A TYPICAL CONTAINMENT VESSEL UNDER SERVICE CONDITIONS (open access)

EVALUATION OF TROQUE VS CLOSURE BOLT PRELOAD FOR A TYPICAL CONTAINMENT VESSEL UNDER SERVICE CONDITIONS

Radioactive material package containment vessels typically employ bolted closures of various configurations. Closure bolts must retain the lid of a package and must maintain required seal loads, while subjected to internal pressure, impact loads and vibration. The need for insuring that the specified preload is achieved in closure bolts for radioactive materials packagings has been a continual subject of concern for both designers and regulatory reviewers. The extensive literature on threaded fasteners provides sound guidance on design and torque specification for closure bolts. The literature also shows the uncertainty associated with use of torque to establish preload is typically between 10 and 35%. These studies have been performed under controlled, laboratory conditions. The ability to insure required preload in normal service is, consequently, an important question. The study described here investigated the relationship between indicated torque and resulting bolt load for a typical radioactive materials package closure using methods available under normal service conditions.
Date: February 16, 2010
Creator: Smith, A.
Object Type: Article
System: The UNT Digital Library
Counts-in-Cylinders in the Sloan Digital Sky Survey with Comparisons to N-Body (open access)

Counts-in-Cylinders in the Sloan Digital Sky Survey with Comparisons to N-Body

Environmental statistics provide a necessary means of comparing the properties of galaxies in different environments and a vital test of models of galaxy formation within the prevailing, hierarchical cosmological model. We explore counts-in-cylinders, a common statistic defined as the number of companions of a particular galaxy found within a given projected radius and redshift interval. Galaxy distributions with the same two-point correlation functions do not necessarily have the same companion count distributions. We use this statistic to examine the environments of galaxies in the Sloan Digital Sky Survey, Data Release 4. We also make preliminary comparisons to four models for the spatial distributions of galaxies, based on N-body simulations, and data from SDSS DR4 to study the utility of the counts-in-cylinders statistic. There is a very large scatter between the number of companions a galaxy has and the mass of its parent dark matter halo and the halo occupation, limiting the utility of this statistic for certain kinds of environmental studies. We also show that prevalent, empirical models of galaxy clustering that match observed two- and three-point clustering statistics well fail to reproduce some aspects of the observed distribution of counts-in-cylinders on 1, 3 and 6-h{sup -1}Mpc scales. All models …
Date: December 16, 2010
Creator: Berrier, Heather D.; Barton, Elizabeth J.; /UC, Irvine; Berrier, Joel C.; U., /Arkansas; Bullock, James S. et al.
Object Type: Article
System: The UNT Digital Library
Experimental Design for a Sponge-Wipe Study to Relate the Recovery Efficiency and False Negative Rate to the Concentration of a Bacillus anthracis Surrogate for Six Surface Materials (open access)

Experimental Design for a Sponge-Wipe Study to Relate the Recovery Efficiency and False Negative Rate to the Concentration of a Bacillus anthracis Surrogate for Six Surface Materials

Two concerns were raised by the Government Accountability Office following the 2001 building contaminations via letters containing Bacillus anthracis (BA). These included the: 1) lack of validated sampling methods, and 2) need to use statistical sampling to quantify the confidence of no contamination when all samples have negative results. Critical to addressing these concerns is quantifying the probability of correct detection (PCD) (or equivalently the false negative rate FNR = 1 − PCD). The PCD/FNR may depend on the 1) method of contaminant deposition, 2) surface concentration of the contaminant, 3) surface material being sampled, 4) sample collection method, 5) sample storage/transportation conditions, 6) sample processing method, and 7) sample analytical method. A review of the literature found 17 laboratory studies that focused on swab, wipe, or vacuum samples collected from a variety of surface materials contaminated by BA or a surrogate, and used culture methods to determine the surface contaminant concentration. These studies quantified performance of the sampling and analysis methods in terms of recovery efficiency (RE) and not PCD/FNR (which left a major gap in available information). Quantifying the PCD/FNR under a variety of conditions is a key aspect of validating sample and analysis methods, and also for …
Date: December 16, 2010
Creator: Piepel, Gregory F.; Amidan, Brett G.; Krauter, Paula & Einfeld, Wayne
Object Type: Report
System: The UNT Digital Library
Fabrication of a 238Pu target (open access)

Fabrication of a 238Pu target

Precision neutron-induced reaction data are important for modeling the network of isotope production and destruction within a given diagnostic chain. This network modeling has many applications such as the design of advanced fuel cycle for reactors and the interpretation of radiochemical data related to the stockpile stewardship and nuclear forensics projects. Our current funded effort is to improve the neutron-induced reaction data on the short-lived actinides and the specific goal is to improve the neutron capture data on {sup 238}Pu with a half-life of 87.7 years. In this report, the fabrication of a {sup 238}Pu target for the proposed measurement using the DANCE array at LANL is described. The {sup 238}Pu target was fabricated from a sample enriched to 99.35%, acquired from ORNL. A total of 395 {micro}g was electroplated onto both sides of a 3 {micro}m thick Ti foil using a custom-made plating cell, shown in Fig 1. The target-material loaded Ti foil is sandwiched between two double-side aluminized mylar foils with a thickness of 1.4 {micro}m. The mylar foil is glued to a polyimide ring. This arrangement is shown partially in Fig. 2. The assembled target is then inserted into an aluminum container with a wall thickness of …
Date: November 16, 2010
Creator: Wu, C Y; Chyzh, A; Kwan, E; Henderson, R; Gostic, J & Carter, D
Object Type: Report
System: The UNT Digital Library
Surface current reduction of (211) oriented Cd0.46Zn0.04Te0.50 crystals by Ar bombardment (open access)

Surface current reduction of (211) oriented Cd0.46Zn0.04Te0.50 crystals by Ar bombardment

Cd{sub 0.46}Zn{sub 0.04}Te{sub .50} crystals have been exposed to high density Ar plasmas in order to modify the surface chemistry and control the surface conductivity. X-ray photoelectron spectroscopy (XPS) reveals that this bombardment results in a modified surface atomic ratio, with Cd being preferentially removed compared to Te. In addition, the native oxide is removed and suppressed for an extended period of time. Current-voltage data is analyzed in order to determine the effect on surface leakage current after exposure. It is found that surface leakage current can be decreased by approximately 2.5 orders of magnitude following Ar{sup +} bombardment.
Date: March 16, 2010
Creator: Voss, L F; Beck, P R; Conway, A M; Graff, R T; Nikolic, R J; Nelson, A J et al.
Object Type: Article
System: The UNT Digital Library
Broadband Infrared Heterodyne Spectrometer: Final Report (open access)

Broadband Infrared Heterodyne Spectrometer: Final Report

This report summarizes the most important results of our effort to develop a new class of infrared spectrometers based on a novel broadband heterodyne design. Our results indicate that this approach could lead to a near-room temperature operation with performance limited only by quantum noise carried by the incoming signal. Using a model quantum-well infrared photodetector (QWIP), we demonstrated key performance features of our approach. For example, we directly measured the beat frequency signal generated by superimposing local oscillator (LO) light of one frequency and signal light of another through a spectrograph, by injecting the LO light at a laterally displaced input location. In parallel with the development of this novel spectrometer, we modeled a new approach to reducing detector volume though plasmonic resonance effects. Since dark current scales directly with detector volume, this ''photon compression'' can directly lead to lower currents. Our calculations indicate that dark current can be reduced by up to two orders of magnitude in an optimized ''superlens'' structure. Taken together, our spectrometer and dark current reduction strategies provide a promising path toward room temperature operation of a mid-wave and possibly long-wave infrared spectrometer.
Date: December 16, 2010
Creator: Stevens, C G; Cunningham, C T & Tringe, J W
Object Type: Report
System: The UNT Digital Library
Fermi Liquid Instabilities in the Spin Channel (open access)

Fermi Liquid Instabilities in the Spin Channel

We study the Fermi surface instabilities of the Pomeranchuk type in the spin triplet channel with high orbital partial waves (F{sub l}{sup a} (l > 0)). The ordered phases are classified into two classes, dubbed the {alpha} and {beta}-phases by analogy to the superfluid {sup 3}He-A and B-phases. The Fermi surfaces in the {alpha}-phases exhibit spontaneous anisotropic distortions, while those in the {beta}-phases remain circular or spherical with topologically non-trivial spin configurations in momentum space. In the {alpha}-phase, the Goldstone modes in the density channel exhibit anisotropic overdamping. The Goldstone modes in the spin channel have nearly isotropic underdamped dispersion relation at small propagating wavevectors. Due to the coupling to the Goldstone modes, the spin wave spectrum develops resonance peaks in both the {alpha} and {beta}-phases, which can be detected in inelastic neutron scattering experiments. In the p-wave channel {beta}-phase, a chiral ground state inhomogeneity is spontaneously generated due to a Lifshitz-like instability in the originally nonchiral systems. Possible experiments to detect these phases are discussed.
Date: March 16, 2010
Creator: Wu, Congjun; /Santa Barbara, KITP; Sun, Kai; Fradkin, Eduardo; /Illinois U., Urbana; Zhang, Shou-Cheng et al.
Object Type: Article
System: The UNT Digital Library
Assessment of the Proposed INTEC CPP 666 Stack Monitoring Site for Compliance with ANSI/HPS N13.1 1999 (open access)

Assessment of the Proposed INTEC CPP 666 Stack Monitoring Site for Compliance with ANSI/HPS N13.1 1999

This document reports on a series of tests to determine whether the proposed new location for air sampling probes in the CPP-666 heating, ventilation and air conditioning (HVAC) exhaust duct would meet the applicable regulatory criteria regarding the placement of an air sampling probe. Federal regulations( ) require that a sampling probe be located in the exhaust stack according to the criteria of the American National Standards Institute/Health Physical Society (ANSI/HPS) N13.1-1999, Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stack and Ducts of Nuclear Facilities. These criteria address the capability of the sampling probe to extract a sample that is representative of the effluent stream.
Date: February 16, 2010
Creator: Glissmeyer, John A. & Flaherty, Julia E.
Object Type: Report
System: The UNT Digital Library
Shape Selective Nano-Catalysts: Toward Direct Methanol Fuel Cells Applications (open access)

Shape Selective Nano-Catalysts: Toward Direct Methanol Fuel Cells Applications

A series of bimetallic core-shell-alloy type Au-Pt nanomaterials with various morphologies, aspect ratios and compositions, were produced in a heterogenous epitaxial fashion. Gold nanoparticles with well-controlled particle size and shape, e.g. spheres, rods and cubes, were used as 'seeds' for platinum growth in the presence of a mild reducing agent, ascorbic acid and a cationic surfactant cethyltrimethyl ammonium bromide (CTAB). The reactions take place in air and water, and are quick, economical and amenable for scaling up. The synthesized nanocatalysts were characterized by electron microscopy techniques and energy dispersive X-ray analysis. Nafion membranes were embedded with the Au-Pt nanomaterials and analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM) for their potential in direct methanol fuel cells applications.
Date: June 16, 2010
Creator: Murph, S.
Object Type: Article
System: The UNT Digital Library
Final Work Plan : Phase II Investigation of Potential Contamination at the Former CCC/USDA Grain Storage Facility in Savannah, Missouri. (open access)

Final Work Plan : Phase II Investigation of Potential Contamination at the Former CCC/USDA Grain Storage Facility in Savannah, Missouri.

From approximately 1949 until 1970, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) operated a grain storage facility on federally owned property approximately 0.25 mi northwest of Savannah, Missouri (Figure 1.1). During this time, commercial grain fumigants containing carbon tetrachloride were commonly used by the CCC/USDA and the private grain storage industry to preserve grain in their facilities. In November 1998, carbon tetrachloride was detected in a private well (Morgan) roughly 50 ft south of the former CCC/USDA facility, as a result of statewide screening of private wells near former CCC/USDA facilities, conducted in Missouri by the U.S. Environmental Protection Agency (EPA 1999). The 1998 and subsequent investigations by the EPA and the Missouri Department of Natural Resources (MoDNR) confirmed the presence of carbon tetrachloride in the Morgan well, as well as in a second well (on property currently occupied by the Missouri Department of Transportation [MoDOT]) described as being approximately 400 ft east of the former CCC/USDA facility. The identified concentrations in these two wells were above the EPA maximum contaminant level (MCL) and the Missouri risk-based corrective action default target level (MRBCA DTL) values of 5.0 {micro}g/L for carbon tetrachloride in water used for domestic …
Date: August 16, 2010
Creator: LaFreniere, L. M. & Division, Environmental Science
Object Type: Report
System: The UNT Digital Library
Expansion of Michigan EOR Operations Using Advanced Amine Technology at a 600 MW Project Wolverine Carbon Capture and Storage Project (open access)

Expansion of Michigan EOR Operations Using Advanced Amine Technology at a 600 MW Project Wolverine Carbon Capture and Storage Project

Wolverine Power Supply Cooperative Inc, a member owned cooperative utility based in Cadillac Michigan, proposes to demonstrate the capture, beneficial utilization and storage of CO{sub 2} in the expansion of existing Enhanced Oil Recovery operations. This project is being proposed in response to the US Department of Energy Solicitation DE-FOA-0000015 Section III D, 'Large Scale Industrial CCS projects from Industrial Sources' Technology Area 1. The project will remove 1,000 metric tons per day of CO{sub 2} from the Wolverine Clean Energy Venture 600 MW CFB power plant owned and operated by WPC. CO{sub 2} from the flue gas will be captured using Hitachi's CO{sub 2} capture system and advanced amine technology. The capture system with the advanced amine-based solvent supplied by Hitachi is expected to significantly reduce the cost and energy requirements of CO{sub 2} capture compared to current technologies. The captured CO{sub 2} will be compressed and transported for Enhanced Oil Recovery and CO{sub 2} storage purposes. Enhanced Oil Recovery is a proven concept, widely used to recover otherwise inaccessible petroleum reserves. While post-combustion CO{sub 2} capture technologies have been tested at the pilot scale on coal power plant flue gas, they have not yet been demonstrated at a …
Date: June 16, 2010
Creator: Hoffman, H; kishinevsky, Y; Wu, S.; Pardini, R.; Tripp, E. & Barnes, D.
Object Type: Report
System: The UNT Digital Library
Background Radiation Survey of the Radiological/Nuclear Countermeasures Test and Evaluation Center (open access)

Background Radiation Survey of the Radiological/Nuclear Countermeasures Test and Evaluation Center

In preparation for operations at the Radiological/Nuclear Countermeasures Test and Evaluation Complex (Rad/NucCTEC), the Department of Homeland Security Domestic Nuclear Detection Office (DHS/DNDO) requested that personnel from the Remote Sensing Laboratory (RSL) conduct a survey of the present radiological conditions at the facility. The measurements consist of the exposure rate from a high-pressure ion chamber (HPIC), high-resolution spectra from a high-purity germanium (HPGe) system in an in situ configuration, and low-resolution spectra from a sodium iodide (NaI) detector in a radiation detection backpack. Measurements with these systems were collected at discrete locations within the facility. Measurements were also collected by carrying the VECTOR backpack throughout the complex to generate a map of the entire area. The area was also to be surveyed with the Kiwi (an array of eight-2-inch x 4-inch x 16-inch NaI detectors) from the Aerial Measuring Systems; however, conflicts with test preparation activities at the site prevented this from being accomplished.
Date: September 16, 2010
Creator: Okada, Colin
Object Type: Report
System: The UNT Digital Library
A Comparison of Two Thermal Insulation and Structural Materials for Use in Type B Packagings (open access)

A Comparison of Two Thermal Insulation and Structural Materials for Use in Type B Packagings

This paper presents the summary of design features and test results of two Type B Shipping Package prototype configurations comprising different insulating materials developed by the Savannah River National Laboratory (SRNL) for the Department of Energy. The materials evaluated, a closed-cell polyurethane foam and a vacuformed ceramic fiber material, were selected to provide adequate structural protection to the package containment vessel during Normal Conditions of Transport (NCT) and Hypothetical Accident Condition (HAC) events and to provide thermal protection during the HAC fire. Polyurethane foam has been used in shipping package designs for many years because of the stiffness it provides to the structure and because of the thermal protection it provides during fire scenarios. This comparison describes how ceramic fiber material offers an alternative to the polyurethane foam in a specific overpack design. Because of the high operating temperature ({approx}2,300 F) of the ceramic material, it allows for contents with higher heat loads to be shipped than is possible with polyurethane foam. Methods of manufacturing and design considerations using the two materials will be addressed.
Date: July 16, 2010
Creator: Blanton, P. & Eberl, K.
Object Type: Article
System: The UNT Digital Library
Comparison of EXAFS Foil Spectra from Around the World (open access)

Comparison of EXAFS Foil Spectra from Around the World

The EXAFS spectra of Cu and Pd foil from many different beamlines and synchrotrons are compared to address the dependence of the amplitude reduction factor (S{sub 0}{sup 2}) on beamline specific parameters. Even though S{sub 0}{sup 2} is the same parameter as the EXAFS coordination number, the value for S{sub 0}{sup 2} is given little attention, and is often unreported. The S{sub 0}{sup 2} often differs for the same material due to beamline and sample attributes, such that no importance is given to S{sub 0}{sup 2}-values within a general range of 0.7 to 1.1. EXAFS beamlines have evolved such that it should now be feasible to use standard S{sub 0}{sup 2} values for all EXAFS measurements of a specific elemental environment. This would allow for the determination of the imaginary energy (Ei) to account for broadening of the EXAFS signal rather than folding these errors into an effective S{sub 0}{sup 2}-value. To test this concept, we model 11 Cu-foil and 6 Pd-foil EXAFS spectra from around the world to compare the difference in S{sub 0}{sup 2}- and Ei-values.
Date: July 16, 2010
Creator: Kelly, S. D.; Bare, S. R.; Greenlay, N.; Azevedo, G.; Balasubramanian, M.; Barton, D. et al.
Object Type: Article
System: The UNT Digital Library
Development of a new generation of optical slope measuring profiler (open access)

Development of a new generation of optical slope measuring profiler

A collaboration, including all DOE synchrotron labs, industrial vendors of x-ray optics, and with active participation of the HBZ-BESSY-II optics group has been established to work together on a new slope measuring profiler -- the optical slope measuring system (OSMS). The slope measurement accuracy of the instrument is expected to be<50 nrad for the current and future metrology of x-ray optics for the next generation of light sources. The goals were to solidify a design that meets the needs of mirror specifications and also be affordable; and to create a common specification for fabrication of a multi-functional translation/scanning (MFTS) system for the OSMS. This was accomplished by two collaborative meetings at the ALS (March 26, 2010) and at the APS (May 6, 2010).
Date: September 16, 2010
Creator: Yashchuk, Valeriy V.; Takacs, Peter Z.; McKinney, Wayne R.; Assoufid, Lahsen; Siewert, Frank & Zeschke, Thomas
Object Type: Article
System: The UNT Digital Library
Full Electromagnetic Fel Simulation via the Lorentz-Boosted Frame Transformation (open access)

Full Electromagnetic Fel Simulation via the Lorentz-Boosted Frame Transformation

Numerical electromagnetic simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz-boosted frame. A particularly good application for calculation in a boosted frame isthat of short wavelength free-electron lasers (FELs) where a high energy electron beam with small fractional energy spread interacts with a static magnetic undulator. In the optimal boost frame (i.e., the ponderomotive rest frame), the red-shifted FEL radiation and blue-shifted undulator field have identical wavelengths and the number of required longitudinal grid cells and time-steps for fully electromagnetic simulation (relative to the laboratory frame) decrease by factors of gamma^2 each. In theory, boosted frame EM codes permit direct study of FEL problems for which the eikonal approximation for propagation of the radiation field and wiggler-period-averaging for the particle-field interaction may be suspect. We have adapted the WARP code to apply this method to several electromagnetic FEL problems including spontaneous emission, strong exponential gain in a seeded, single pass amplifier configuration, and emission from e-beams in undulators with multiple harmonic components. WARP has a standard relativistic macroparticle mover and a fully 3-D electromagnetic field solver. We discuss our boosted frame results and …
Date: August 16, 2010
Creator: Fawley, William & Vay, Jean-Luc
Object Type: Article
System: The UNT Digital Library
Advanced Compton scattering light source R&D at LLNL (open access)

Advanced Compton scattering light source R&D at LLNL

We report the design and current status of a monoenergetic laser-based Compton scattering 0.5-2.5 MeV {gamma}-ray source. Previous nuclear resonance fluorescence results and future linac and laser developments for the source are presented. At MeV photon energies relevant for nuclear processes, Compton scattering light sources are attractive because of their relative compactness and improved brightness above 100 keV, compared to typical 4th generation synchrotrons. Recent progress in accelerator physics and laser technology have enabled the development of a new class of tunable Mono-Energetic Gamma-Ray (MEGa-Ray) light sources based on Compton scattering between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A new precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linac designed in collaboration with SLAC will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. Based on the success of the previous Thomson-Radiated Extreme X-rays (T-REX) Compton scattering source at LLNL, the source will be used to excite nuclear resonance fluorescence lines in various isotopes; applications include …
Date: February 16, 2010
Creator: Albert, F.; Anderson, S. G.; Anderson, G.; Betts, S. M.; Chu, T. S.; Gibson, D. J. et al.
Object Type: Article
System: The UNT Digital Library
Lithium and Zinc Sulfide Coated Plastic Neutron Detector Test (open access)

Lithium and Zinc Sulfide Coated Plastic Neutron Detector Test

Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. There is a declining supply of 3He in the world, and thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Four technologies have been identified as being currently commercially available, potential alternative neutron detectors to replace the use of 3He in RPMs. In addition, a few other companies have detector technologies that might be competitive in the near term as an alternative technology. Reported here are the results of tests of 6Li/ZnS(Ag)-coated scintillator paddles. This testing measured the required performance for neutron detection efficiency and gamma ray rejection capabilities of a system manufactured by Symetrica.
Date: July 16, 2010
Creator: Kouzes, Richard T. & Ely, James H.
Object Type: Report
System: The UNT Digital Library
Untangling the Chemical Evolution of Titan's Atmosphere and Surface -- From Homogeneous to Heterogeneous Chemistry (open access)

Untangling the Chemical Evolution of Titan's Atmosphere and Surface -- From Homogeneous to Heterogeneous Chemistry

The arrival of the Cassini-Huygens probe at Saturn's moon Titan - the only Solar System body besides Earth and Venus with a solid surface and a thick atmosphere with a pressure of 1.4 atm at surface level - in 2004 opened up a new chapter in the history of Solar System exploration. The mission revealed Titan as a world with striking Earth-like landscapes involving hydrocarbon lakes and seas as well as sand dunes and lava-like features interspersed with craters and icy mountains of hitherto unknown chemical composition. The discovery of a dynamic atmosphere and active weather system illustrates further the similarities between Titan and Earth. The aerosol-based haze layers, which give Titan its orange-brownish color, are not only Titan's most prominent optically visible features, but also play a crucial role in determining Titan's thermal structure and chemistry. These smog-like haze layers are thought to be very similar to those that were present in Earth's atmosphere before life developed more than 3.8 billion years ago, absorbing the destructive ultraviolet radiation from the Sun, thus acting as 'prebiotic ozone' to preserve astrobiologically important molecules on Titan. Compared to Earth, Titan's low surface temperature of 94 K and the absence of liquid water …
Date: March 16, 2010
Creator: Kaiser, Ralf I.; Maksyutenko, Pavlo; Ennis, Courtney; Zhang, Fangtong; Gu, Xibin; Krishtal, Sergey P. et al.
Object Type: Article
System: The UNT Digital Library
Switching a magnetic vortex by interlayer coupling in epitaxially grown Co/Cu/Py/Cu(001) trilayer disks (open access)

Switching a magnetic vortex by interlayer coupling in epitaxially grown Co/Cu/Py/Cu(001) trilayer disks

Epitaxial Py/Cu/Co/Cu(001) trilayers were patterned into micron sized disks and imaged using element-specific photoemission electron microscopy. By varying the Cu spacer layer thickness, we study how the coupling between the two magnetic layers influences the formation of magnetic vortex states. We find that while the Py and Co disks form magnetic vortex domains when the interlayer coupling is ferromagnetic, the magnetic vortex domains of the Py and Co disks break into anti-parallel aligned multidomains when the interlayer coupling is antiferromagnetic. We explain this result in terms of magnetic flux closure between the Py and Co layers for the antiferromagnetic coupling case.
Date: July 16, 2010
Creator: Wu, J.; Carlton, D.; Oelker, E.; Park, J. S.; Jin, E.; Arenholz, E. et al.
Object Type: Article
System: The UNT Digital Library
Final Work Plan : Phase I Investigation of Potential Contamination at the Former CCC/USDA Grain Storage Facility in Montgomery City, Missouri. (open access)

Final Work Plan : Phase I Investigation of Potential Contamination at the Former CCC/USDA Grain Storage Facility in Montgomery City, Missouri.

From September 1949 until September 1966, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) leased property at the southeastern end of Montgomery City, Missouri, for the operation of a grain storage facility. During this time, commercial grain fumigants containing carbon tetrachloride were commonly used by the CCC/USDA and the private grain storage industry to preserve grain in their facilities. In January 2000, carbon tetrachloride was detected in a soil sample (220 {micro}g/kg) and two soil gas samples (58 {micro}g/m{sup 3} and 550 {micro}g/m{sup 3}) collected at the former CCC/USDA facility, as a result of a pre-CERCLIS site screening investigation (SSI) performed by TN & Associates, Inc., on behalf of the U.S. Environmental Protection Agency (EPA), Region VII (MoDNR 2001). In June 2001, the Missouri Department of Natural Resources (MoDNR) conducted further sampling of the soils and groundwater at the former CCC/USDA facility as part of a preliminary assessment/site inspection (PA/SI). The MoDNR confirmed the presence of carbon tetrachloride (at a maximum identified concentration of 2,810 {micro}g/kg) and chloroform (maximum 82 {micro}g/kg) in the soils and also detected carbon tetrachloride and chloroform (42.2 {micro}g/L and 58.4 {micro}g/L, respectively) in a groundwater sample collected at the former facility (MoDNR …
Date: August 16, 2010
Creator: LaFreniere, L. M. & Division, Environmental Science
Object Type: Report
System: The UNT Digital Library
Exploration of Resource and Transmission Expansion Decisions in the Western Renewable Energy Zone Initiative (open access)

Exploration of Resource and Transmission Expansion Decisions in the Western Renewable Energy Zone Initiative

Building transmission to reach renewable energy (RE) goals requires coordination among renewable developers, utilities and transmission owners, resource and transmission planners, state and federal regulators, and environmental organizations. The Western Renewable Energy Zone (WREZ) initiative brings together a diverse set of voices to develop data, tools, and a unique forum for coordinating transmission expansion in the Western Interconnection. In this report we use a new tool developed in the WREZ initiative to evaluate possible renewable resource selection and transmission expansion decisions. We evaluate these decisions under a number of alternative future scenarios centered on meeting 33% of the annual load in the Western Interconnection with new renewable resources located within WREZ-identified resource hubs. Of the renewable resources in WREZ resource hubs, and under the assumptions described in this report, our analysis finds that wind energy is the largest source of renewable energy procured to meet the 33% RE target across nearly all scenarios analyzed (38-65%). Solar energy is almost always the second largest source (14-41%). Solar exceeds wind by a small margin only when solar thermal energy is assumed to experience cost reductions relative to all other technologies. Biomass, geothermal, and hydropower are found to represent a smaller portion of …
Date: February 16, 2010
Creator: Mills, Andrew; Phadke, Amol & Wiser, Ryan
Object Type: Report
System: The UNT Digital Library
New Isotope 263Hs (open access)

New Isotope 263Hs

A new isotope of Hs was produced in the reaction 208Pb(56Fe, n)263Hs at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. Six genetically correlated nuclear decay chains have been observed and assigned to the new isotope 263Hs. The measured cross section was 21+13-8.4 pb at 276.4 MeV lab-frame center-of-target beam energy. 263Hs decays with a half-life of 0.74 ms by alpha-decay and the measured alpha-particle energies are 10.57 +- 0.06, 10.72 +- 0.06, and 10.89 +- 0.06 MeV. The experimental cross section is compared to a theoretical prediction based on the Fusion by Diffusion model [W. J. Swiatecki et al., Phys. Rev. C 71, 014602 (2005)].
Date: March 16, 2010
Creator: Dragojevic, I.; Gregorich, K. E.; Dullmann, Ch. E.; Dvorak, J.; Ellison, P. A.; Gates, J. M. et al.
Object Type: Article
System: The UNT Digital Library