Electron Density Measurements in the National Spherical Torus Experiment Detached Divertor Region Using Stark Broadening of Deuterium Infrared Paschen Emission Lines (open access)

Electron Density Measurements in the National Spherical Torus Experiment Detached Divertor Region Using Stark Broadening of Deuterium Infrared Paschen Emission Lines

Spatially resolved measurements of deuterium Balmer and Paschen line emission have been performed in the divertor region of the National Spherical Torus Experiment using a commercial 0.5 m Czerny-Turner spectrometer. While the Balmer emission lines, Balmer and Paschen continua in the ultraviolet and visible regions have been extensively used for tokamak divertor plasma temperature and density measurements, the diagnostic potential of infrared Paschen lines has been largely overlooked. We analyze Stark broadening of the lines corresponding to 2-n and 3-m transitions with principle quantum numbers n = 7-12 and m = 10-12 using recent Model Microfield Method calculations (C. Stehle and R. Hutcheon, Astron. Astrophys. Supl. Ser. 140, 93 (1999)). Densities in the range (5-50) x 10{sup 19} m{sup -3} are obtained in the recombining inner divertor plasma in 2-6 MW NBI H-mode discharges. The measured Paschen line profiles show good sensitivity to Stark effects, and low sensitivity to instrumental and Doppler broadening. The lines are situated in the near-infrared wavelength domain, where optical signal extraction schemes for harsh nuclear environments are practically realizable, and where a recombining divertor plasma is optically thin. These properties make them an attractive recombining divertor density diagnostic for a burning plasma experiment.
Date: April 27, 2007
Creator: Soukhanovskii, V A; Johnson, D W; Kaita, R & Roquemore, A L
Object Type: Article
System: The UNT Digital Library
Local Three-Nucleon Interaction from Chiral Effective Field Theory (open access)

Local Three-Nucleon Interaction from Chiral Effective Field Theory

None
Date: April 27, 2007
Creator: Navratil, P
Object Type: Article
System: The UNT Digital Library
A Radiocarbon Chronology of Hunter-Gatherer Occupation from Bodega Bay, California, USA (open access)

A Radiocarbon Chronology of Hunter-Gatherer Occupation from Bodega Bay, California, USA

The evolution of hunter-gatherer maritime adaptations in western North America has been a prominent topic of discussion among archaeologists in recent years (e.g. Arnold 1992; Erlandson and Colten 1991; Erlandson and Glassow 1997; Lightfoot 1993). Although vast coastal regions of the northeastern Pacific (for example, southern California) have been investigated in detail, our understanding of hunter-gatherer developments along the coast of northern California is limited. Previous research indicates that humans have exploited marine mammals, fish and shellfish along the northern California shoreline since the early Holocene (Schwaderer 1992). By the end of the late Holocene, some groups remained year-round on the coast subsisting primarily on marine resources (e.g. Gould 1975; Hildebrandt and Levulett 2002). However, a paucity of well-dated cultural deposits has hindered our understanding of these developments, particularly during the early and middle Holocene. The lack of a long and reliable chronological sequence has restricted our interpretations of behavioral change, including the adaptive strategies (such as foraging, mobility and settlement) used by human foragers to colonize and inhabit the coastal areas of this region. These shortcomings have also hindered comparative interpretations with other coastal and inland regions in western North America. Here we present a Holocene radiocarbon chronology of …
Date: April 27, 2005
Creator: Kennedy, M. A.; Russell, A. D. & Guilderson, T. P.
Object Type: Article
System: The UNT Digital Library
Metals Processing Laboratory Users (MPLUS) Facility Annual Report FY 2002 (October 1, 2001-September 30, 2002) (open access)

Metals Processing Laboratory Users (MPLUS) Facility Annual Report FY 2002 (October 1, 2001-September 30, 2002)

The Metals Processing Laboratory Users Facility (MPLUS) is a Department of Energy (DOE), Energy Efficiency and Renewable Energy, Industrial Technologies Program, user facility designated to assist researchers in key industries, universities, and federal laboratories in improving energy efficiency, improving environmental aspects, and increasing competitiveness. The goal of MPLUS is to provide access to the specialized technical expertise and equipment needed to solve metals processing issues that limit the development and implementation of emerging metals processing technologies. The scope of work can also extend to other types of materials. MPLUS has four primary user centers: (1) Processing--casting, powder metallurgy, deformation processing (including extrusion, forging, rolling), melting, thermomechanical processing, and high-density infrared processing; (2) Joining--welding, monitoring and control, solidification, brazing, and bonding; (3) Characterization--corrosion, mechanical properties, fracture mechanics, microstructure, nondestructive examination, computer-controlled dilatometry, and emissivity; and (4) Materials/Process Modeling--mathematical design and analyses, high-performance computing, process modeling, solidification/deformation, microstructure evolution, thermodynamic and kinetic, and materials databases A fully integrated approach provides researchers with unique opportunities to address technologically related issues to solve metals processing problems and probe new technologies. Access is also available to 16 additional Oak Ridge National Laboratory (ORNL) user facilities ranging from state-of-the-art materials characterization capabilities, and high-performance computing to …
Date: April 27, 2004
Creator: Angelini, P
Object Type: Report
System: The UNT Digital Library
Extracellular Proteins Limit the Dispersal of BiogenicNanoparticles (open access)

Extracellular Proteins Limit the Dispersal of BiogenicNanoparticles

High spatial-resolution secondaryion microprobespectrometry, synchrotron radiation Fourier-transform infraredspectroscopy and polyacrylamide gel analysis demonstrate the intimateassociation of proteins with spheroidal aggregates of biogenic zincsulfide nanocrystals, an example of extracellular biomineralization.Experiments involving synthetic ZnS nanoparticles and representativeamino acids indicate a driving role for cysteine in rapid nanoparticleaggregation. These findings suggest that microbially-derivedextracellular proteins can limit dispersal of nanoparticulatemetal-bearing phases, such as the mineral products of bioremediation,that may otherwise be transported away from their source by subsurfacefluid flow.
Date: April 27, 2007
Creator: Moreau, John W.; Weber, Peter K.; Martin, Michael C.; Gilbert,Benjamin; Hutcheon, Ian D. & Banfield, Jillian F.
Object Type: Article
System: The UNT Digital Library
Biomolecular Modification of Inorganic Crystal Growth (open access)

Biomolecular Modification of Inorganic Crystal Growth

The fascinating shapes and hierarchical designs of biomineralized structures are an inspiration to materials scientists because of the potential they suggest for biomolecular control over materials synthesis. Conversely, the failure to prevent or limit tissue mineralization in the vascular, skeletal, and urinary systems is a common source of disease. Understanding the mechanisms by which organisms direct or limit crystallization has long been a central challenge to the biomineralization community. One prevailing view is that mineral-associated macromolecules are responsible for either inhibiting crystallization or initiating and stabilizing non-equilibrium crystal polymorphs and morphologies through interactions between anionic moieties and cations in solution or at mineralizing surfaces. In particular, biomolecules that present carboxyl groups to the growing crystal have been implicated as primary modulators of growth. Here we review the results from a combination of in situ atomic force microscopy (AFM) and molecular modeling (MM) studies to investigate the effect of specific interactions between carboxylate-rich biomolecules and atomic steps on crystal surfaces during the growth of carbonates, oxalates and phosphates of calcium. Specifically, we how the growth kinetics and morphology depend on the concentration of additives that include citrate, simple amino acids, synthetic Asp-rich polypeptides, and naturally occurring Asp-rich proteins found in both …
Date: April 27, 2007
Creator: De Yoreo, J. J.
Object Type: Book
System: The UNT Digital Library
A velocity map imaging spectrometer for electron?ion and ion?ion coincidence experiments with synchrotron radiation (open access)

A velocity map imaging spectrometer for electron?ion and ion?ion coincidence experiments with synchrotron radiation

We have built a velocity imaging (VMI) spectrometer optimized for angle-resolved photoionization experiments with synchrotron radiation (SR) in the VUV and soft X-tay range. The spectrometer is equiped with four electrostatic lenses that focus the charged photoionization products onto a position-sensitive multi-hit delay-line anode. The use of two additional electrostatic lens elements as compared to the standard design of Eppink and Parker [T.J.B. Eppink and D.H. Parker, Rev. Sci. Instrum. 68 (1997) 3477]provides better focusing of an extended interaction region, which is crucial for most SR applications. Furthermore, the apparatus is equipped with a second micro-channel plate detector opposite to the VMI spectrometer, enabling electron-ion coincidence experiments and thereby mass-resolved ion spectroscopy independent of the time structure of the synchrotron radiation. First results for the photofragmentation of CO2 molecules are presented.
Date: April 27, 2007
Creator: Lawrence Berkeley National Laboratory. Advanced Light Source.
Object Type: Article
System: The UNT Digital Library
Measuring the Repassivation Potential of Alloy 22 Using the Potentiodynamic - Galvanostatic - Potentiostatic Method (open access)

Measuring the Repassivation Potential of Alloy 22 Using the Potentiodynamic - Galvanostatic - Potentiostatic Method

Traditionally, the susceptibility of Alloy 22 (N06022) to suffer crevice corrosion has been measured using the Cyclic Potentiodynamic Polarization (CPP) technique (ASTM G 61). When the alloy is not very susceptible to crevice corrosion, the values of repassivation potential obtained using the CPP technique are not highly reproducible. To circumvent the large uncertainty in the values of the repassivation potential by the CPP method, the repassivation potential of Alloy 22 may be measured using a slower method that combines sequentially potentiodynamic, galvanostatic and potentiostatic treatments (this method is called the Tsujikawa-Hisamatsu Electrochemical or THE method). In the THE method the anodic charge is applied to the specimen in a more controlled manner, which avoids driving the alloy to transpassivity and therefore results in more reproducible repassivation potential values. Results using THE method under various testing conditions are presented. A new standard has been prepared for ASTM balloting for the THE method. The round robin matrix results are also discussed.
Date: April 27, 2007
Creator: Evans, K J & Rebak, R B
Object Type: Article
System: The UNT Digital Library
QCD FACTORIZATION FOR SEMI-INCLUSIVE DEEP INELASTIC SCATTERING. (open access)

QCD FACTORIZATION FOR SEMI-INCLUSIVE DEEP INELASTIC SCATTERING.

In this talk, we will present a QCD factorization theorem for the semi-inclusive deep-inelastic scattering with hadrons in the current fragmentation region detected at low transverse momentum.
Date: April 27, 2005
Creator: YUAN, F.
Object Type: Article
System: The UNT Digital Library
California Wintertime Precipitation in Regional and Global Climate Models (open access)

California Wintertime Precipitation in Regional and Global Climate Models

In this paper, wintertime precipitation from a variety of observational datasets, regional climate models (RCMs), and general circulation models (GCMs) is averaged over the state of California (CA) and compared. Several averaging methodologies are considered and all are found to give similar values when model grid spacing is less than 3{sup o}. This suggests that CA is a reasonable size for regional intercomparisons using modern GCMs. Results show that reanalysis-forced RCMs tend to significantly overpredict CA precipitation. This appears to be due mainly to overprediction of extreme events; RCM precipitation frequency is generally underpredicted. Overprediction is also reflected in wintertime precipitation variability, which tends to be too high for RCMs on both daily and interannual scales. Wintertime precipitation in most (but not all) GCMs is underestimated. This is in contrast to previous studies based on global blended gauge/satellite observations which are shown here to underestimate precipitation relative to higher-resolution gauge-only datasets. Several GCMs provide reasonable daily precipitation distributions, a trait which doesn't seem tied to model resolution. GCM daily and interannual variability is generally underpredicted.
Date: April 27, 2009
Creator: Caldwell, P M
Object Type: Article
System: The UNT Digital Library
Summary Report on Information Technology Integration Activities For project to Enhance NASA Tools for Coastal Managers in the Gulf of Mexico and Support Technology Transfer to Mexico (open access)

Summary Report on Information Technology Integration Activities For project to Enhance NASA Tools for Coastal Managers in the Gulf of Mexico and Support Technology Transfer to Mexico

Deliverable to NASA Stennis Space Center summarizing summarizes accomplishments made by Battelle and its subcontractors to integrate NASA's COAST visualization tool with the Noesis search tool developed under the Gulf of Mexico Regional Collaborative project.
Date: April 27, 2009
Creator: Gulbransen, Thomas C.
Object Type: Report
System: The UNT Digital Library

Reliability Challenges for Solar Energy (Presentation)

PV industry can benefit from reliability testing experience of microelectronics industry . Si modules perform well in field; CdTe/CIGS must be sealed to moisture; CPV in product development stage.
Date: April 27, 2009
Creator: Kurtz, S.
Object Type: Presentation
System: The UNT Digital Library
Suzaku Observations of PSR B1259-63: A New Manifestation of Relativistic Pulsar Wind (open access)

Suzaku Observations of PSR B1259-63: A New Manifestation of Relativistic Pulsar Wind

We observed PSR B1259-63, a young non-accreting pulsar orbiting around a Be star SS 2883, eight times with the Suzaku satellite from July to September 2007, to characterize the X-ray emission arising from the interaction between a pulsar relativistic wind and Be star outflows. The X-ray spectra showed a featureless continuum in 0.6-10 keV, modeled by a power law with a wide range of photon index 1.3-1.8. When combined with the Suzaku PIN detector which allowed spectral analysis in the hard 15-50 keV band, X-ray spectra do show a break at {approx} 5 keV in a certain epoch. Regarding the PSR B1259-63 system as a compactified pulsar wind nebula, in which e{sup {+-}} pairs are assumed to be accelerated at the inner shock front of the pulsar wind, we attribute the X-ray spectral break to the low-energy cutoff of the synchrotron radiation associated with the Lorentz factor of the relativistic pulsar wind {gamma}{sub 1} {approx} 4 x 10{sup 5}. Our result indicates that Comptonization of stellar photons by the unshocked pulsar wind will be accessible (or tightly constrained) by observations with the Fermi Gamma-ray Space Telescope during the next periastron passage. The PSR B1259-63 system allows us to probe the …
Date: April 27, 2009
Creator: Uchiyama, Yasunobu; Tanaka, Takaaki; Takahashi, Tadayuki; Mori, Koji & Nakazawa, Kazuhiro
Object Type: Article
System: The UNT Digital Library
Sampling and Characterization of 618-2 Anomalous Material (open access)

Sampling and Characterization of 618-2 Anomalous Material

Excavation of the 618-2 Burial Ground has produced many items of anomalous waste. Prior to temporary packaging and/or storage, these items have been characterized in the field to identify radiological and industrial safety conditions.
Date: April 27, 2006
Creator: Zacharias, A.E.
Object Type: Report
System: The UNT Digital Library
LITERATURE SURVEY OF GASEOUS HYDROGEN EFFECTS ON THE MECHANICAL PROPERTIES OF CARBON AND LOW ALLOY STEELS (open access)

LITERATURE SURVEY OF GASEOUS HYDROGEN EFFECTS ON THE MECHANICAL PROPERTIES OF CARBON AND LOW ALLOY STEELS

Literature survey has been performed for a compendium of mechanical properties of carbon and low alloy steels following hydrogen exposure. The property sets include yield strength, ultimate tensile strength, uniform elongation, reduction of area, threshold stress intensity factor, fracture toughness, and fatigue crack growth. These properties are drawn from literature sources under a variety of test methods and conditions. However, the collection of literature data is by no means complete, but the diversity of data and dependency of results in test method is sufficient to warrant a design and implementation of a thorough test program. The program would be needed to enable a defensible demonstration of structural integrity of a pressurized hydrogen system. It is essential that the environmental variables be well-defined (e.g., the applicable hydrogen gas pressure range and the test strain rate) and the specimen preparation be realistically consistent (such as the techniques to charge hydrogen and to maintain the hydrogen concentration in the specimens).
Date: April 27, 2009
Creator: Lam, P; Andrew Duncan, A; Robert Sindelar, R & Thad Adams, T
Object Type: Article
System: The UNT Digital Library
THERMAL EVALUATION OF DRUM TYPE RADIOACTIVE MATERIAL PACKAGING ARRAYS IN STORAGE (open access)

THERMAL EVALUATION OF DRUM TYPE RADIOACTIVE MATERIAL PACKAGING ARRAYS IN STORAGE

Drum type packages are routinely used to transport radioactive material (RAM) in the U.S. Department of Energy (DOE) complex. These packages are designed to meet the federal regulations described in 10 CFR 71.[1] In recent years, there has been a greater need to use these packagings to store the excess fissile material, especially plutonium for long term storage. While the design requirements for safe transportation of these packagings are well defined, the requirements for safe long term storage are not well established. Since the RAM contents in the packagings produce decay heat, it is important that they are stored carefully to prevent overheating of the containment vessel (CV) seals to prevent any leakage and the impact limiter to maintain the package structural integrity. This paper analyzes different storage arrays for a typical 9977 packaging for thermal considerations and makes recommendations for their safe storage under normal operating conditions.
Date: April 27, 2009
Creator: Gupta, N
Object Type: Article
System: The UNT Digital Library
Identification and Assessment of Material Models for Age-Related Degradation of Structures and Passive Components in Nuclear Power Plants (open access)

Identification and Assessment of Material Models for Age-Related Degradation of Structures and Passive Components in Nuclear Power Plants

When performing seismic safety assessments of nuclear power plants (NPPs), the potential effects of age-related degradation on structures, systems, and components (SSCs) should be considered. To address the issue of aging degradation, the Korea Atomic Energy Research Institute (KAERI) has embarked on a five-year research project to develop a realistic seismic risk evaluation system which will include the consideration of aging of structures and components in NPPs. Three specific areas that are included in the KAERI research project, related to seismic probabilistic risk assessment (PRA), are probabilistic seismic hazard analysis, seismic fragility analysis including the effects of aging, and a plant seismic risk analysis. To support the development of seismic capability evaluation technology for degraded structures and components, KAERI entered into a collaboration agreement with Brookhaven National Laboratory (BNL) in 2007. The collaborative research effort is intended to continue over a five year period with the goal of developing seismic fragility analysis methods that consider the potential effects of age-related degradation of SSCs, and using these results as input to seismic PRAs. In the Year 1 scope of work BNL collected and reviewed degradation occurrences in US NPPs and identified important aging characteristics needed for the seismic capability evaluations that …
Date: April 27, 2009
Creator: Nie,J.; Braverman, J.; Hofmayer, C.; Kim, M. K. & Choi, I-K.
Object Type: Report
System: The UNT Digital Library
Constraints and Superspin for SuperPoincare Algebras in Diverse Dimensions (open access)

Constraints and Superspin for SuperPoincare Algebras in Diverse Dimensions

We generalize to arbitrary dimension the construction of a covariant and supersymmetric constraint for the massless superPoincare algebra, which was given for the eleven-dimensional case in a previous work. We also contrast it with a similar construction appropriate to the massive case. Finally we show that the constraint uniquely fixes the representation of the algebra.
Date: April 27, 2004
Creator: Pasqua, Andrea & Zumino, Bruno
Object Type: Article
System: The UNT Digital Library
Resonant Kicker System Development at SLAC (open access)

Resonant Kicker System Development at SLAC

The design and installation of the Linear Coherent Light Source [1] at SLAC National Accelerator Laboratory has included the development of a kicker system for selective beam bunch dumping. The kicker is based on an LC resonant topology formed by the 50 uF energy storage capacitor and the 64 uH air core magnet load which has a sinusoidal pulse period of 400us. The maximum magnet current is 500 A. The circuit is weakly damped, allowing most of the magnet energy to be recovered in the energy storage capacitor. The kicker runs at a repetition rate of 120Hz. A PLC-based control system provides remote control and monitoring of the kicker via EPICS protocol. Fast timing and interlock signals are converted by discrete peak-detect and sample-hold circuits into DC signals that can be processed by the PLC. The design and experimental characterization of the system are presented.
Date: April 27, 2009
Creator: Beukers, Tony; Krzaszczak, John; Larrus, Marc & Lira, Antonio de
Object Type: Article
System: The UNT Digital Library
Potential bias of model projected greenhouse warming in irrigated regions (open access)

Potential bias of model projected greenhouse warming in irrigated regions

Atmospheric general circulation models (GCMs) used to project climate responses to increased CO{sub 2} generally omit irrigation of agricultural land. Using the NCAR CAM3 GCM coupled to a slab-ocean model, we find that inclusion of an extreme irrigation scenario has a small effect on the simulated temperature and precipitation response to doubled CO{sub 2} in most regions, but reduced warming by as much as 1 C in some agricultural regions, such as Europe and India. This interaction between CO{sub 2} and irrigation occurs in cases where agriculture is a major fraction of the land surface and where, in the absence of irrigation, soil moisture declines are projected to provide a positive feedback to temperature change. The reduction of warming is less than 25% of the temperature increase modeled for doubled CO{sub 2} in most regions; thus greenhouse warming will still be dominant. However, the results indicate that land use interactions may be an important component of climate change uncertainty in some agricultural regions. While irrigated lands comprise only {approx}2% of the land surface, they contribute over 40% of global food production. Climate changes in these regions are therefore particularly important to society despite their relatively small contribution to average global …
Date: April 27, 2006
Creator: Lobell, D.; Bala, G.; Bonfils, C. & Duffy, P.
Object Type: Article
System: The UNT Digital Library
Absolute Measurement of Electron Cloud Density in a Positively-Charged Particle Beam (open access)

Absolute Measurement of Electron Cloud Density in a Positively-Charged Particle Beam

Clouds of stray electrons are ubiquitous in particle accelerators and frequently limit the performance of storage rings. Earlier measurements of electron energy distribution and flux to the walls provided only a relative electron cloud density. We have measured electron accumulation using ions expelled by the beam. The ion energy distribution maps the depressed beam potential and gives the dynamic cloud density. Clearing electrode current reveals the static background cloud density, allowing the first absolute measurement of the time-dependent electron cloud density during the beam pulse.
Date: April 27, 2006
Creator: Kireeff Covo, Michel; Molvik, Arthur W.; Friedman, Alex; Vay, Jean-Luc; Seidl, Peter A.; Logan, Grant et al.
Object Type: Article
System: The UNT Digital Library
Low-Fidelity Cross Section Covariances for 219 Fission Products in the First Neutron Region. (open access)

Low-Fidelity Cross Section Covariances for 219 Fission Products in the First Neutron Region.

An extensive set of covariances for neutron cross sections in the energy range 5 keV-20 MeV has been developed to provide initial, low-fidelity but consistent uncertainty data for nuclear criticality safety applications. The methodology for the determination of such covariances combines the nuclear reaction model code EMPIRE, which calculates sensitivity to nuclear reaction model parameters, and the Bayesian code KALMAN to propagate uncertainty of the model parameters to cross sections. Taking into account the large scale of the project (219 fission products), only partial reference to experimental data has been made. Therefore, the covariances are, to a large extent, derived from the perturbation of several critical model parameters selected through the sensitivity analysis. These parameters define optical potential, level densities and pre-equilibrium emission. This work represents the first attempt ever to generate nuclear data covariances on such a scale.
Date: April 27, 2007
Creator: Pigni, M. T.; Herman, M.; Oblozinsky, P. & Rochman, D.
Object Type: Report
System: The UNT Digital Library
Model-based Processing of Microcantilever Sensor Arrays (open access)

Model-based Processing of Microcantilever Sensor Arrays

We have developed a model-based processor (MBP) for a microcantilever-array sensor to detect target species in solution. We perform a proof-of-concept experiment, fit model parameters to the measured data and use them to develop a Gauss-Markov simulation. We then investigate two cases of interest, averaged deflection data and multi-channel data. For this evaluation we extract model parameters via a model-based estimation, perform a Gauss-Markov simulation, design the optimal MBP and apply it to measured experimental data. The performance of the MBP in the multi-channel case is evaluated by comparison to a ''smoother'' (averager) typically used for microcantilever signal analysis. It is shown that the MBP not only provides a significant gain ({approx} 80dB) in signal-to-noise ratio (SNR), but also consistently outperforms the smoother by 40-60 dB. Finally, we apply the processor to the smoothed experimental data and demonstrate its capability for chemical detection. The MBP performs quite well, apart from a correctable systematic bias error.
Date: April 27, 2005
Creator: Tringe, J W; Clague, D S; Candy, J V; Sinensky, A K; Lee, C L; Rudd, R E et al.
Object Type: Article
System: The UNT Digital Library
iSHIELD - A Line Source Application of SHIELD11 (open access)

iSHIELD - A Line Source Application of SHIELD11

iSHIELD11 performs a line-source numerical integration of radiation source terms that are defined by the iSHIELD11 computer code[1] . An example is provided to demonstrate how one can use iSHIELD11 to perform a shielding analysis for a 250 GeV electron linear accelerator.
Date: April 27, 2006
Creator: Nelson, W. R. & Rokni, S. H.
Object Type: Report
System: The UNT Digital Library