12.6 keV Kr K-alpha X-ray Source For High Energy Density Physics Experiments (open access)

12.6 keV Kr K-alpha X-ray Source For High Energy Density Physics Experiments

A high contrast 12.6 keV Kr K{alpha} source has been demonstrated on the petawatt-class Titan laser facility. The contrast ratio (K{alpha} to continuum) is 65, with a competitive ultra short pulse laser to x-ray conversion efficiency of 10{sup -5}. Filtered shadowgraphy indicates that the Kr K{alpha} and K{beta} x-rays are emitted from a roughly 1 x 2 mm emission volume, making this source suitable for area backlighting and scattering. Spectral calculations indicate a typical bulk electron temperature of 50-70 eV (i.e. mean ionization state 13-16), based on the observed ratio of K{alpha} to K{beta}. Kr gas jets provide a debris-free high energy K{alpha} source for time-resolved diagnosis of dense matter.
Date: April 22, 2008
Creator: Kugland, N.; Constantin, C. G.; Niemann, C.; Neumayer, P.; Chung, H.; Doppner, T. et al.
System: The UNT Digital Library
The Aims and Activities of the International Network of Nuclear Structure and Decay Data Evaluators. (open access)

The Aims and Activities of the International Network of Nuclear Structure and Decay Data Evaluators.

International Network of Nuclear Structure and Decay Data (NSDD) Evaluators consists of a number of evaluation groups and data service centers in several countries that appreciate the merits of working together to maintain and ensure the quality and comprehensive content of the ENSDF database (Evaluated Nuclear Structure Data File). Biennial meetings of the network are held under the auspices of the International Atomic Energy Agency (IAEA) to assign evaluation responsibilities, monitor progress, discuss improvements and emerging difficulties, and agree on actions to be undertaken by individual members. The evaluated data and bibliographic details are made available to users via various media, such as the journals ''Nuclear Physics A'' and ''Nuclear Data Sheets'', the World Wide Web, on CD-ROM, wall charts of the nuclides and ''Nuclear Wallet Cards''. While the ENSDF master database is maintained by the US National Nuclear Data Center at the Brookhaven National Laboratory, these data are also available from other nuclear data centers including the IAEA Nuclear Data Section. The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy, in cooperation with the IAEA, organizes workshops on NSDD at regular intervals. The primary aims of these particular workshops are to provide hands-on training in the data …
Date: April 22, 2007
Creator: Nichols, A. L. & Tuli, J. K.
System: The UNT Digital Library
THE ART OF COLLECTING EXPERIMENTAL DATA INTERNATIONALLY: EXFOR, CINDA AND THE NRDC NETWORK. (open access)

THE ART OF COLLECTING EXPERIMENTAL DATA INTERNATIONALLY: EXFOR, CINDA AND THE NRDC NETWORK.

The world-wide network of nuclear reaction data centers (NRDC) has, for about 40 years, provided data services to the scientific community. This network covers all types of nuclear reaction data, including neutron-induced, charged-particle-induced, and photonuclear data, used in a wide range of applications, such as fission reactors, accelerator driven systems, fusion facilities, nuclear medicine, materials analysis, environmental monitoring, and basic research. The now 13 nuclear data centers included in the NRDC are dividing the efforts of compilation and distribution for particular types of reactions and/or geographic regions all over the world. A central activity of the network is the collection and compilation of experimental nuclear reaction data and the related bibliographic information in the EXFOR and CINDA databases. Many of the individual data centers also distribute other types of nuclear data information, including evaluated data libraries, nuclear structure and decay data, and nuclear data reports. The network today ensures the world-wide transfer of information and coordinated evolution of an important source of nuclear data for current and future nuclear applications.
Date: April 22, 2007
Creator: Henriksson, H.; Schwerer, O.; Rochman, D.; Mikhaylyukova, M. V. & Otuka, N.
System: The UNT Digital Library
ATCA for Machines-- Advanced Telecommunications Computing Architecture (open access)

ATCA for Machines-- Advanced Telecommunications Computing Architecture

The Advanced Telecommunications Computing Architecture is a new industry open standard for electronics instrument modules and shelves being evaluated for the International Linear Collider (ILC). It is the first industrial standard designed for High Availability (HA). ILC availability simulations have shown clearly that the capabilities of ATCA are needed in order to achieve acceptable integrated luminosity. The ATCA architecture looks attractive for beam instruments and detector applications as well. This paper provides an overview of ongoing R&D including application of HA principles to power electronics systems.
Date: April 22, 2008
Creator: Larsen, R.S.
System: The UNT Digital Library
Black carbon emissions in the United Kingdom during the past four decades: An empirical analysis (open access)

Black carbon emissions in the United Kingdom during the past four decades: An empirical analysis

We use data from a unique 40-year record of 150 urban and rural stations in the ''Black Smoke and SO2 Network'' in Great Britain to infer information about sources of atmospheric black carbon (BC). The data show a rapid decline of ambient atmospheric BC between 1962 and the early 1990s that exceeds the decline in official estimates of BC emissions based only on amount of fuel use and mostly fixed emission factors. This provides empirical confirmation of the existence and large impact of a time-dependent ''technology factor'' that must multiply the rate of fossil fuel use. Current ambient BC amounts in Great Britain comparable to those in western and central Europe, with diesel engines being the principal present source. From comparison of BC and SO2 data we infer that current BC emission inventories understate true emissions in the U.K. by about a factor of two. The results imply that there is the potential for improved technology to achieve large reduction of global ambient BC. There is a need for comparable monitoring of BC in other countries.
Date: April 22, 2004
Creator: Novakov, T. & Hansen, J.E.
System: The UNT Digital Library
Bounding CKM Mixing with a Fourth Family (open access)

Bounding CKM Mixing with a Fourth Family

CKM mixing between third family quarks and a possible fourth family is constrained by global fits to the precision electroweak data. The dominant constraint is from nondecoupling oblique corrections rather than the vertex correction to Z {yields} {bar b}b used in previous analyses. The possibility of large mixing suggested by some recent analyses of FCNC processes is excluded, but 3-4 mixing of the same order as the Cabbibo mixing of the first two families is allowed.
Date: April 22, 2009
Creator: Chanowitz, Michael S.
System: The UNT Digital Library
Chemically Vapor Deposited Yttria-Stabilized Zirconia (YSZ) for Thermal and Environmental Barrier Coating (open access)

Chemically Vapor Deposited Yttria-Stabilized Zirconia (YSZ) for Thermal and Environmental Barrier Coating

Yttria-stabilized zirconia (YSZ) is used as a thermal barrier coating (TBC) to protect super-alloy blades such as Mar-M247 or Rene-N5 during engine operation. The current method for YSZ fabrication for TBC applications is by air-plasma spraying (APS) or electron beam physical vapor deposition (EB-PVD) (Haynes 1997). APS gives reasonable deposition rates, but has a limited life and aging effects due to its porous and lamellar structure. The EB-PVD coatings are more stable and can accommodate thermomechanical stresses due to their characteristic strain-tolerant, columnar microstructure. EB-PVD, however, is primarily line-of-sight, which often leaves ''hidden areas'' uncoated, has low throughput, and has high capital cost. The process of metal-organic chemical vapor deposition (MOCVD) is investigated here as an economical alternative to EB-PVD and APS, with the potential for better overall coverage as well as the ability to produce thick (100-250 {micro}m), strain-tolerant, columnar coatings. MOCVD of YSZ involves the use of zirconium and yttrium organometallic precursors reacting with an oxygen source. Previous researchers have used diketonate or chloride precursors and oxygen (Wahl et al. 2001a, Wahl et al. 2001b, Yamane and Harai 1989). These precursors have low transport rates due to their low carrier solvent solubility (Varanasi et al. 2003). Solvated zirconium …
Date: April 22, 2003
Creator: Varanasi, V. G.; Besmann, T. M.; Lothian, J. L.; Xu, W. & Starr, T. L.
System: The UNT Digital Library
Coal-ash Corrosion of Alloys for Combustion Power Plants (open access)

Coal-ash Corrosion of Alloys for Combustion Power Plants

A program on coal-ash corrosion is being conducted at Argonne National Laboratory to evaluate the performance of several structural alloys in the presence of mixtures of synthetic coal ash, alkali sulfates, and alkali chlorides. Candidate alloys are also exposed in a small-scale coal-fired combustor at the National Energy Technology Laboratory in Pittsburgh. Experiments in the present program, which addresses the effects of deposit chemistry, temperature, and alloy chemistry on the corrosion response of alloys, were conducted at temperatures in the range of 575-800 C for time periods up to {approx}1850 h. Fe-base alloys selected for the study included HR3C, 310TaN, HR120, SAVE 25, NF709, modified 800, 347HFG, and HCM12A. In addition, 800H clad with Alloy 671 was included in several of the exposures. Ni-base alloys selected for the study included 600, 601, 617, 690, 625, 602CA, 214, 230, 45TM, HR 160, and 693. Data were obtained on weight change, scale thickness, internal penetration, microstructural characteristics of corrosion products, mechanical integrity of the scales, and cracking of scales. Results showed that the relationship of corrosion rates to temperature followed a bell-shaped curve for Fe-base alloys, with peak rates at {approx}725 C, but the rate itself was dependent on the alloy chemistry. …
Date: April 22, 2003
Creator: Natesan, K.; Purohit, A. & Rink, D. L.
System: The UNT Digital Library
Coal Ash Corrosion Resistant Materials Testing Program (open access)

Coal Ash Corrosion Resistant Materials Testing Program

The "Coal Ash Corrosion Resistant Materials Testing Program" is being conducted by The Babcock & Wilcox Company (B&W), the U.S. Department of Energy (DOE) and the Ohio Coal Development Office (OCDO) at Reliant Energy’s Niles plant in Niles, Ohio to provide full-scale, in-situ testing of recently developed boiler superheater materials. Fireside corrosion is a key issue for improving efficiency of new coal fired power plants and improving service life in existing plants. In November 1998, B&W began development of a system to permit testing of advanced tube materials at metal temperatures typical of advanced supercritical steam temperatures (1100°F and higher) in a boiler exhibiting coal ash corrosive conditions. Several materials producers including Oak Ridge National Laboratory (ORNL) contributed advanced materials to the project. In the spring of 1999 a system consisting of three identical sections, each containing multiple segments of twelve different materials, was installed. The sections are cooled by reheat steam, and are located just above the furnace entrance in Niles’ Unit #1, a 110 MWe unit firing high sulfur Ohio coal. In November 2001 the first section was removed for thorough metallurgical evaluation after 33 months of operation. The second and third sections remain in service and the …
Date: April 22, 2003
Creator: McDonald, D.K.
System: The UNT Digital Library
A Comparison of EPIcode and ALOHA Calculations for Pool Evaporation and Chemical Atmospheric Transport and Dispersion. (open access)

A Comparison of EPIcode and ALOHA Calculations for Pool Evaporation and Chemical Atmospheric Transport and Dispersion.

EPIcode (version 7.0) and ALOHA (version 5.2.3) are two of the designated toolbox codes identified in the Department of Energy's Implementation Plan for DNFSB Recommendation 2002-1 on Software Quality Assurance issues in the DOE Complex. Both have the capability to estimate evaporation rates from pools formed from chemical spills and to predict subsequent atmospheric transport and dispersion. This paper provides an overview of the algorithms used by EPIcode and ALOHA to calculate evaporation rates and downwind plume concentrations. The technical bases for these algorithms are briefly discussed, and differences in the EPIcode and ALOHA methodologies highlighted. In addition, sample calculations are performed using EPIcode and ALOHA for selected chemicals under various environmental conditions. Side-by-side comparisons of results from sample calculations are analyzed to illustrate the impact that the different methodologies used by EPIcode and ALOHA have on predicted evaporation rates and downwind concentrations.
Date: April 22, 2005
Creator: Andrew, VINCENT
System: The UNT Digital Library
The complete mitochondrial genome of a gecko and the phylogeneticposition of the Middle Eastern teratoscincus keyserlingii (open access)

The complete mitochondrial genome of a gecko and the phylogeneticposition of the Middle Eastern teratoscincus keyserlingii

Sqamate reptiles are traditionally divided into six groups: Iguania, Anguimorpha, Scincomorpha, Gekkota (these four are lizards), Serpentes (snakes), and Amphisbaenia (the so-called worm lizards). Currently there are complete mitochondrial genomes from two representatives of the Iguania (Janke et al., 2001; Kumazawa, 2004), three from the Anguimorpha (Kumazawa, 2004; Kumazawa and Endo, 2004), two from the Scincomorpha (Kumazawa and Nishida, 1999; Kumazawa, 2004), two from Serpentes (Kumazawa et al., 1998; Kumazawa, 2004) and 12 from Amphisbaenia (Macey et al., 2004). The only traditional group of Squamata from which a complete mitochondrial genome has not been sequenced is the Gekkota. Here we report the complete mitochondrial genome of Teratoscincus keyserlingii, a Middle Eastern representative of the Gekkota. The gekkonid lizard genus Teratoscincus is distributed throughout the deserts of central and southwest Asia as shown in figure 1, with five species currently recognized (Macey et al. 1997a, 1999b). Included in this figure are the positions of mountain ranges discussed in the text; see also figure 1 in Macey et al. (1999b). Two species, T. bedriagai and T. microlepis, are restricted to Southwest Asia south of the Kopet Dagh and Hindu Kush in Iran, Afghanistan, and Pakistan (Anderson, 1999). Two species are found in …
Date: April 22, 2005
Creator: Macey, J. Robert; Fong, Jonathan J.; Kuehl, Jennifer V.; Shafiei,Soheila; Ananjeva, Natalia B.; Papenfuss, Theodore J. et al.
System: The UNT Digital Library
Correlation and Prediction of Partition Coefficients from the Gas Phase and from Water to Alkan-1-ols (open access)

Correlation and Prediction of Partition Coefficients from the Gas Phase and from Water to Alkan-1-ols

Article discussing correlation and prediction of partition coefficients from the gas phase and from water to alkan-1-ols.
Date: April 22, 2008
Creator: Abraham, M. H. (Michael H.); Nasezadeh, Asadollah & Acree, William E. (William Eugene)
System: The UNT Digital Library
Decamethylytterbocene Complexes of Bipyridines and Diazabutadienes: Multiconfigurational Ground States and Open-Shell Singlet Formation (open access)

Decamethylytterbocene Complexes of Bipyridines and Diazabutadienes: Multiconfigurational Ground States and Open-Shell Singlet Formation

Partial ytterbium f-orbital occupancy (i.e., intermediate valence) and open-shell singlet formation are established for a variety of bipyridine and diazabutadiene adducts with decamethylytterbocene, (C5Me5)2Yb, abbreviated as Cp*2Yb. Data used to support this claim include ytterbium valence measurements using Yb LIII-edge X-ray absorption near-edge structure spectroscopy, magnetic susceptibility, and complete active space self-consistent field (CASSCF) multiconfigurational calculations, as well as structural measurements compared to density functional theory calculations. The CASSCF calculations indicate that the intermediate valence is the result of a multiconfigurational ground-state wave function that has both an open-shell singlet f13(?*)1, where pi* is the lowest unoccupied molecular orbital of the bipyridine or dpiazabutadiene ligands, and a closed-shell singlet f14 component. A number of other competing theories for the unusual magnetism in these materials are ruled out by the lack of temperature dependence of the measured intermediate valence. These results have implications for understanding chemical bonding not only in organolanthanide complexes but also for f-element chemistry in general, as well as understanding magnetic interactions in nanoparticles and devices.
Date: April 22, 2009
Creator: Booth, Corwin H.; Walter, Marc D.; Kazhdan, Daniel; Hu, Yung-Jin; Lukens, Wayne W.; Bauer, Eric D. et al.
System: The UNT Digital Library
DEFORMATION DEPENDENT TUL MULTI-STEP DIRECT MODEL (open access)

DEFORMATION DEPENDENT TUL MULTI-STEP DIRECT MODEL

The Multi-Step Direct (MSD) module TRISTAN in the nuclear reaction code EMPIRE has been extended in order to account for nuclear deformation. The new formalism was tested in calculations of neutron emission spectra emitted from the {sup 232}Th(n,xn) reaction. These calculations include vibration-rotational Coupled Channels (CC) for the inelastic scattering to low-lying collective levels, ''deformed'' MSD with quadrupole deformation for inelastic scattering to the continuum, Multi-Step Compound (MSC) and Hauser-Feshbach with advanced treatment of the fission channel. Prompt fission neutrons were also calculated. The comparison with experimental data shows clear improvement over the ''spherical'' MSD calculations and JEFF-3.1 and JENDL-3.3 evaluations.
Date: April 22, 2007
Creator: WIENKE,H.; CAPOTE, R.; HERMAN, M. & SIN, M.
System: The UNT Digital Library
Design Competition for Development of a General Purpose Fissile Package (open access)

Design Competition for Development of a General Purpose Fissile Package

Department of Transportation (DOT) 6M specification packages have been used extensively for transportation of radioactive materials since the 1960s. The objective of the Savannah River Site (SRS) design competition was to advance the development of a new performance-based and compliance-certifiable package as a candidate for replacement of the obsolescent DOT 6M/6L specification package.
Date: April 22, 2003
Creator: Houghtaling, T. K.
System: The UNT Digital Library
Development of a Commercial Process for the Production of Silicon Carbide Fibrils (open access)

Development of a Commercial Process for the Production of Silicon Carbide Fibrils

The current work continues a project completed in 1999 by ReMaxCo Technologies in which a novel, microwave based, VLS Silicon Carbide Fibrils concept was verified. This project continues the process development of a pilot scale commercial reactor. Success will lead to sufficient quantities of fibrils to expand work by ORNL and others on heat exchanger tube development. A semicontinuous, microwave heated, vacuum reactor was designed, fabricated and tested in these experiments. Cylindrical aluminum oxide reaction boats are coated, on the inner surface, with a catalyst and placed into the reactor under a light vacuum. A series of reaction boats are then moved, one at a time, through the reactor. Each boat is first preheated with resistance heaters to 850 C to 900 C. Each reaction boat is then moved, in turn, to the microwave heated section. The catalyst is heated to the required temperature of 1200 C to 1300 C while a mixture of MTS (methyl trichlorosilane) and hydrogen are introduced into the annulus of the boat. The MTS is dissociated to allow the carbon and silicon components to be dissolved into the catalyst. The catalyst saturates and precipitates silicon carbide onto the surface of the reaction boat to grow …
Date: April 22, 2003
Creator: Nixdorf, Richard D.
System: The UNT Digital Library
Dissipative Cryogenic Filters with Zero DC Resistance (open access)

Dissipative Cryogenic Filters with Zero DC Resistance

The authors designed, implemented and tested cryogenic RF filters with zero DC resistance, based on wires with a superconducting core inside a resistive sheath. The superconducting core allows low frequency currents to pass with negligible dissipation. Signals above the cutoff frequency are dissipated in the resistive part due to their small skin depth. The filters consist of twisted wire pairs shielded with copper tape. Above approximately 1 GHz, the attenuation is exponential in {radical}{omega}, as typical for skin depth based RF filters. By using additional capacitors of 10 nF per line, an attenuation of at least 45 dB above 10 MHz can be obtained. Thus, one single filter stage kept at mixing chamber temperature in a dilution refrigerator is sufficient to attenuate room temperature black body radiation to levels corresponding to 10 mK above about 10 MHz.
Date: April 22, 2008
Creator: Bluhm, Hendrik; Moler, Kathryn A. & /Stanford U., Appl. Phys. Dept
System: The UNT Digital Library
Empire Ultimate Expansion: Resonances and Covariances. (open access)

Empire Ultimate Expansion: Resonances and Covariances.

The EMPIRE code system is being extended to cover the resolved and unresolved resonance region employing proven methodology used for the production of new evaluations in the recent Atlas of Neutron Resonances. Another directions of Empire expansion are uncertainties and correlations among them. These include covariances for cross sections as well as for model parameters. In this presentation we concentrate on the KALMAN method that has been applied in EMPIRE to the fast neutron range as well as to the resonance region. We also summarize role of the EMPIRE code in the ENDF/B-VII.0 development. Finally, large scale calculations and their impact on nuclear model parameters are discussed along with the exciting perspectives offered by the parallel supercomputing.
Date: April 22, 2007
Creator: Herman, M.; Mughabghab, S. F.; Oblozinsky, P.; Rochman, D.; Pigni, M. T.; Kawano, T. et al.
System: The UNT Digital Library
Erratum: Bounds and Estimates for Elastic Constants of Random Polycrystals of Laminates (open access)

Erratum: Bounds and Estimates for Elastic Constants of Random Polycrystals of Laminates

None
Date: April 22, 2005
Creator: Berger, E. L.
System: The UNT Digital Library
Evaluation Of Microdosing Strategies For Studies In Preclinical Drug Development: Demonstration Of Linear Pharmacokinetics In Dogs Of A Nucleoside Analogue Over A 50-Fold Dose Range (open access)

Evaluation Of Microdosing Strategies For Studies In Preclinical Drug Development: Demonstration Of Linear Pharmacokinetics In Dogs Of A Nucleoside Analogue Over A 50-Fold Dose Range

The technique of accelerator mass spectrometry (AMS) was validated successfully and utilized to study the pharmacokinetics and disposition in dogs of a preclinical drug candidate (Compound A), after oral and intravenous administration. The primary objective of this study was to examine whether Compound A displayed linear kinetics across sub-pharmacological (microdose) and pharmacological dose ranges in an animal model, prior to initiation of a human microdose study. The AMS-derived disposition properties of Compound A were comparable to data obtained via conventional techniques such as LC-MS/MS and liquid scintillation counting analyses. Thus, Compound A displayed multiphasic kinetics and possessed low plasma clearance (4.4 mL/min/kg), a long terminal elimination half-life (19.4 hr) and high oral bioavailability (82%). Currently there are no published comparisons of the kinetics of a pharmaceutical compound at pharmacological versus sub-pharmacological doses employing microdosing strategies. The present study thus provides the first description of the pharmacokinetics of a drug candidate assessed under these two dosing regimens. The data demonstrated that the pharmacokinetic properties of Compound A were similar following dosing at 0.02 mg/kg as at 1 mg/kg, indicating that in the case of Compound A, the kinetics of absorption, distribution and elimination in the dog appear to be linear across …
Date: April 22, 2004
Creator: Sandhu, P; Vogel, J S; Rose, M J; Ubick, E A; Brunner, J E; Wallace, M A et al.
System: The UNT Digital Library
EVALUATION OF TUNGSTEN ISOTOPES IN THE FAST NEUTRON RANGE INCLUDING CROSS-SECTION COVARIANCE ESTIMATION. (open access)

EVALUATION OF TUNGSTEN ISOTOPES IN THE FAST NEUTRON RANGE INCLUDING CROSS-SECTION COVARIANCE ESTIMATION.

New evaluations for the tungsten isotopes {sup 180,182,183,184,186}W in the neutron energy range up to 60 MeV were produced. In the resonance range only minor adjustments to the resonance parameters were made due to a lack of adequate experimental data. Evaluations in the fast energy region were based on nuclear model calculations using the EMPIRE-2.19 code. Recently derived dispersive coupled-channel optical model potentials for W and Ta isotopes were instrumental to achieve a very good description of the available microscopic cross-section database. Model covariance data were generated with the Monte Carlo technique to produce a prior estimate for the covariance matrix. Experimental data were introduced through the GANDR system. The evaluated files were tested on selected fusion neutronics benchmarks and showed marked improvement compared to other existing evaluations.
Date: April 22, 2007
Creator: CAPOTE,R.; SIN, M.; TRKOV, A.; HERMAN, M.; CARLSON, B.V. & OBLOZINSKY, P.
System: The UNT Digital Library
Extension of the Empire Code to the Resonance Region (open access)

Extension of the Empire Code to the Resonance Region

The preliminary version of a new module has been developed to be added to a nuclear reaction model code EMPIRE to allow for an evaluation of neutron cross sections in a resonance region. It automates most of the evaluation procedures and can be executed within EMPIRE or as a stand-alone program. The module includes a graphic user interface (GUI) and a number of codes and scripts that read individual, as well as average, resonance parameters from the Atlas of Neutron Resonances and other physical constants from RIPL-2, perform an analysis of the available resonances, carry out statistical distributions, and compute cross sections in resolved and unresolved resonance regions which are then compared with experimental data. The module also provides an ENDF-formatted file for a resonance region and various plots allowing for a verification of the procedure. The formatted file can be integrated later into the final ENDF-6 file as generated by the EMPIRE code. However, as a preliminary version, extensive testing and further improvements are needed before this new capability can be incorporated into the production version of EMPIRE.
Date: April 22, 2007
Creator: Cho, Y. S.; Herman, M.; Mughabghab, S. F.; Oblozinsky, P.; Rochman, D. & Lee, Y. O.
System: The UNT Digital Library
EXTENSION OF THE NUCLEAR REACTION MODEL CODE EMPIRE TO ACTINIDES NUCLEAR DATA EVALUATION. (open access)

EXTENSION OF THE NUCLEAR REACTION MODEL CODE EMPIRE TO ACTINIDES NUCLEAR DATA EVALUATION.

Recent extensions and improvements of the EMPIRE code system are outlined. They add new capabilities to the code, such as prompt fission neutron spectra calculations using Hauser-Feshbach plus pre-equilibrium pre-fission spectra, cross section covariance matrix calculations by Monte Carlo method, fitting of optical model parameters, extended set of optical model potentials including new dispersive coupled channel potentials, parity-dependent level densities and transmission through numerically defined fission barriers. These features, along with improved and validated ENDF formatting, exclusive/inclusive spectra, and recoils make the current EMPIRE release a complete and well validated tool for evaluation of nuclear data at incident energies above the resonance region. The current EMPIRE release has been used in evaluations of neutron induced reaction files for {sup 232}Th and {sup 231,233}Pa nuclei in the fast neutron region at IAEA. Triple-humped fission barriers and exclusive pre-fission neutron spectra were considered for the fission data evaluation. Total, fission, capture and neutron emission cross section, average resonance parameters and angular distributions of neutron scattering are in excellent agreement with the available experimental data.
Date: April 22, 2007
Creator: CAPOTE,R.; SIN, M.; TRKOV, A.; HERMAN, M.; CARLSON, B.V. & OBLOZINSKY, P.
System: The UNT Digital Library
FeAl and Mo-Si-B Intermetallic Coatings Prepared by Thermal Spraying (open access)

FeAl and Mo-Si-B Intermetallic Coatings Prepared by Thermal Spraying

FeAl and Mo-Si-B intermetallic coatings for elevated temperature environmental resistance were prepared using high-velocity oxy-fuel (HVOF) and air plasma spray (APS) techniques. For both coating types, the effect of coating parameters (spray particle velocity and temperature) on the microstructure and physical properties of the coatings was assessed. Fe-24Al (wt.%) coatings were prepared using HVOF thermal spraying at spray particle velocities varying from 540 m/s to 700 m/s. Mo-13.4Si-2.6B coatings were prepared using APS at particle velocities of 180 and 350 m/s. Residual stresses in the HVOF FeAl coatings were compressive, while stresses in the APS Mo-Si-B coatings were tensile. In both cases, residual stresses became more compressive with increasing spray particle velocity due to increased peening imparted by the spray particles. The hardness and elastic moduli of FeAl coatings also increased with increasing particle velocity, again due to an increased peening effect. For Mo-Si-B coatings, plasma spraying at 180 m/s resulted in significant oxidation of the spray particles and conversion of the T1 phase into amorphous silica and {alpha}-Mo. The T1 phase was retained after spraying at 350 m/s.
Date: April 22, 2003
Creator: Totemeier, T. C.; Wright, R. N. & Swank, W. D.
System: The UNT Digital Library