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Wolter X-Ray Microscope Computed Tomography Ray-Trace Model with Preliminary Simulation Results
It is proposed to build a Wolter X-ray Microscope Computed Tomography System in order to characterize objects to sub-micrometer resolution. Wolter Optics Systems use hyperbolic, elliptical, and/or parabolic mirrors to reflect x-rays in order to focus or magnify an image. Wolter Optics have been used as telescopes and as microscopes. As microscopes they have been used for a number of purposes such as measuring emission x-rays and x-ray fluoresce of thin biological samples. Standard Computed Tomography (CT) Systems use 2D radiographic images, from a series of rotational angles, acquired by passing x-rays through an object to reconstruct a 3D image of the object. The x-ray paths in a Wolter X-ray Microscope will be considerably different than those of a standard CT system. There is little information about the 2D radiographic images that can be expected from such a system. There are questions about the quality, resolution and focusing range of an image created with such a system. It is not known whether characterization information can be obtained from these images and whether these 2D images can be reconstructed to 3D images of the object. A code has been developed to model the 2D radiographic image created by an object in …
Date:
February 27, 2006
Creator:
Jackson, J A
Object Type:
Report
System:
The UNT Digital Library
Realistic Two-body Interactions in Many-nucleon Systems: Correlated Motion beyond Single-particle Behavior
In the framework of the theory of spectral distributions we perform an overall comparison of three modern realistic interactions, CD-Bonn, CD-Bonn+3terms, and GXPF1 in a broad range of nuclei in the upper fp shell and study their ability to account for the development of isovector pairing correlations and collective rotational motion in many-particle nuclear systems. Our findings reveal a close similarity between CD-Bonn and CD-Bonn+3terms, while both interactions possess features different from the ones of GXPF1. The GXPF1 interaction is used to determine the strength parameter of a quadrupole term that augments an isovector-pairing model interaction with Sp(4) dynamical symmetry, which in turn is shown to yield a reasonable agreement with the experimental low-lying energy spectra of {sup 58}Ni and {sup 58}Cu.
Date:
June 27, 2006
Creator:
Sviratcheva, K.D.; Draayer, J.P. & /Louisiana State U. /Iowa State U. /LLNL, Livermore /SLAC
Object Type:
Report
System:
The UNT Digital Library
Surface structure of CdSe Nanorods revealed by combined X-rayabsorption fine structure measurements and ab-initio calculations
We report orientation-specific, surface-sensitive structural characterization of colloidal CdSe nanorods with extended X-ray absorption fine structure spectroscopy and ab-initio density functional theory calculations. Our measurements of crystallographically-aligned CdSe nanorods show that they have reconstructed Cd-rich surfaces. They exhibit orientation-dependent changes in interatomic distances which are qualitatively reproduced by our calculations. These calculations reveal that the measured interatomic distance anisotropy originates from the nanorod surface.
Date:
January 27, 2006
Creator:
Aruguete, Deborah A.; Marcus, Matthew A.; Li, Liang-shi; Williamson, Andrew; Fakra, Sirine; Gygi, Francois et al.
Object Type:
Article
System:
The UNT Digital Library
Remaining Sites Verification Package for the 100-B-20, 1716-B Maintenance Garage Underground Tank, Waste Site Reclassification Form 2006-019
The 100-B-20 waste site, located in the 100-BC-1 Operable Unit of the Hanford Site, consisted of an underground oil tank that once serviced the 1716-B Maintenance Garage. The selected action for the 100-B-20 waste site involved removal of the oil tanks and their contents and demonstrating through confirmatory sampling that all cleanup goals have been met. In accordance with this evaluation, a reclassification status of interim closed out has been determined. The results demonstrate that the site will support future unrestricted land uses that can be represented by a rural-residential scenario. These results also show that residual concentrations support unrestricted future use of shallow zone soil and that contaminant levels remaining in the soil are protective of groundwater and the Columbia River.
Date:
September 27, 2006
Creator:
Dittmer, L. M.
Object Type:
Report
System:
The UNT Digital Library
Decontamination of Zircaloy Spent Fuel Cladding Hulls
The reprocessing of commercial spent nuclear fuel (SNF) generates a Zircaloy cladding hull waste which requires disposal as a high level waste in the geologic repository. The hulls are primarily contaminated with fission products and actinides from the fuel. During fuel irradiation, these contaminants are deposited in a thin layer of zirconium oxide (ZrO{sub 2}) which forms on the cladding surface at the elevated temperatures present in a nuclear reactor. Therefore, if the hulls are treated to remove the ZrO{sub 2} layer, a majority of the contamination will be removed and the hulls could potentially meet acceptance criteria for disposal as a low level waste (LLW). Discard of the hulls as a LLW would result in significant savings due to the high costs associated with geologic disposal. To assess the feasibility of decontaminating spent fuel cladding hulls, two treatment processes developed for dissolving fuels containing zirconium (Zr) metal or alloys were evaluated. Small-scale dissolution experiments were performed using the ZIRFLEX process which employs a boiling ammonium fluoride (NH{sub 4}F)/ammonium nitrate (NH{sub 4}NO{sub 3}) solution to dissolve Zr or Zircaloy cladding and a hydrofluoric acid (HF) process developed for complete dissolution of Zr-containing fuels. The feasibility experiments were performed using Zircaloy-4 …
Date:
September 27, 2006
Creator:
Rudisill, T. & John Mickalonis, J.
Object Type:
Report
System:
The UNT Digital Library
Interpolation of probability densities in ENDF and ENDL
Suppose that we are given two probability densities p{sub 0}(E{prime}) and p{sub 1}(E{prime}) for the energy E{prime} of an outgoing particle, p{sub 0}(E{prime}) corresponding to energy E{sub 0} of the incident particle and p{sub 1}(E{prime}) corresponding to incident energy E{sub 1}. If E{sub 0} < E{sub 1}, the problem is how to define p{sub {alpha}}(E{prime}) for intermediate incident energies E{sub {alpha}} = (1 - {alpha})E{sub 0} + {alpha}E{sub 1} with 0 < {alpha} < 1. In this note the author considers three ways to do it. They begin with unit-base interpolation, which is standard in ENDL and is sometimes used in ENDF. They then describe the equiprobable bins used by some Monte Carlo codes. They then close with a discussion of interpolation by corresponding-points, which is commonly used in ENDF.
Date:
January 27, 2006
Creator:
Hedstrom, G
Object Type:
Report
System:
The UNT Digital Library
Screening and Ranking Framework (SRF) for Geologic CO2 Storage Site Selection on the Basis of Hse Risk
A screening and ranking framework (SRF) has been developedto evaluate potential geologic carbon dioxide (CO2) storage sites on thebasis of health, safety, and environmental (HSE) risk arising from CO2leakage. The approach is based on the assumption that CO2 leakage risk isdependent on three basic characteristics of a geologic CO2 storage site:(1) the potential for primary containment by the target formation; (2)the potential for secondary containment if the primary formation leaks;and (3) the potential for attenuation and dispersion of leaking CO2 ifthe primary formation leaks and secondary containment fails. Theframework is implemented in a spreadsheet in which users enter numericalscores representing expert opinions or published information along withestimates of uncertainty. Applications to three sites in Californiademonstrate the approach. Refinements and extensions are possible throughthe use of more detailed data or model results in place of propertyproxies.
Date:
November 27, 2006
Creator:
Oldenburg, Curtis M.
Object Type:
Article
System:
The UNT Digital Library
d-alpha correlation functions and collective motion in Xe+Au collisions at E/A=50 MeV
The interplay of the effects of geometry and collective motion on d-{alpha} correlation functions is investigated for central Xe+Au collisions at E/A=50 MeV. The data cannot be explained with out collective motion, which could be partly along the beam axis. A semi-quantitative description of the data can be obtained using a Monte -Carlo model, where thermal emission is superimposed on collective motion. Both the emission volume and the competition between the thermal and collective motion influence significantly the shape of the correlation function, motivating new strategies for extending intensity interferometry studies to massive particles.
Date:
July 27, 2006
Creator:
Verde, G.; Danielewicz, P.; Lynch, W.; Chan, C.; Gelbke, C.; Kwong, L. et al.
Object Type:
Article
System:
The UNT Digital Library
Exact solutions in a model of vertical gas migration
This work is motivated by the growing interest in injectingcarbon dioxide into deep geological formations as a means of avoidingatmospheric emissions of carbon dioxide and consequent global warming.One of the key questions regarding the feasibility of this technology isthe potential rate of leakage out of the primary storage formation. Weseek exact solutions in a model of gas flow driven by a combination ofbuoyancy, viscous and capillary forces. Different combinations of theseforces and characteristic length scales of the processes lead todifferent time scaling and different types of solutions. In the case of athin, tight seal, where the impact of gravity is negligible relative tocapillary and viscous forces, a Ryzhik-type solution implies square-rootof time scaling of plume propagation velocity. In the general case, a gasplume has two stable zones, which can be described by travelling-wavesolutions. The theoretical maximum of the velocity of plume migrationprovides a conservative estimate for the time of vertical migration.Although the top of the plume has low gas saturation, it propagates witha velocity close to the theoretical maximum. The bottom of the plumeflows significantly more slowly at a higher gas saturation. Due to localheterogeneities, the plume can break into parts. Individual plumes alsocan coalesce and from larger plumes. The …
Date:
June 27, 2006
Creator:
Silin, Dmitriy B.; Patzek, Tad W. & Benson, Sally M.
Object Type:
Article
System:
The UNT Digital Library
Asymptotic Analysis of Time-Dependent Neutron Transport Coupled with Isotopic Depletion and Radioactive Decay
We describe an asymptotic analysis of the coupled nonlinear system of equations describing time-dependent three-dimensional monoenergetic neutron transport and isotopic depletion and radioactive decay. The classic asymptotic diffusion scaling of Larsen and Keller [1], along with a consistent small scaling of the terms describing the radioactive decay of isotopes, is applied to this coupled nonlinear system of equations in a medium of specified initial isotopic composition. The analysis demonstrates that to leading order the neutron transport equation limits to the standard time-dependent neutron diffusion equation with macroscopic cross sections whose number densities are determined by the standard system of ordinary differential equations, the so-called Bateman equations, describing the temporal evolution of the nuclide number densities.
Date:
September 27, 2006
Creator:
Brantley, P S
Object Type:
Article
System:
The UNT Digital Library
Greensheet (Houston, Tex.), Vol. 37, No. 454, Ed. 1 Friday, October 27, 2006
Free weekly newspaper that includes business and classified advertising.
Date:
October 27, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 37, No. 140, Ed. 1 Thursday, April 27, 2006
Free weekly newspaper that includes business and classified advertising.
Date:
April 27, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 37, No. 242, Ed. 1 Tuesday, June 27, 2006
Free weekly newspaper that includes business and classified advertising.
Date:
June 27, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 37, No. 141, Ed. 1 Thursday, April 27, 2006
Free weekly newspaper that includes business and classified advertising.
Date:
April 27, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 37, No. 296, Ed. 1 Thursday, July 27, 2006
Free weekly newspaper that includes business and classified advertising.
Date:
July 27, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 37, No. 297, Ed. 1 Thursday, July 27, 2006
Free weekly newspaper that includes business and classified advertising.
Date:
July 27, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 36, No. 610, Ed. 1 Friday, January 27, 2006
Free weekly newspaper that includes business and classified advertising.
Date:
January 27, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Port Aransas South Jetty (Port Aransas, Tex.), Vol. 36, No. 17, Ed. 1 Thursday, April 27, 2006
Weekly newspaper from Port Aransas, Texas on Mustang Island that includes local, state and national news along with extensive advertising.
Date:
April 27, 2006
Creator:
Judson, Mary Henkel
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 37, No. 456, Ed. 1 Friday, October 27, 2006
Free weekly newspaper that includes business and classified advertising.
Date:
October 27, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 37, No. 558, Ed. 1 Wednesday, December 27, 2006
Free weekly newspaper that includes business and classified advertising.
Date:
December 27, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 37, No. 402, Ed. 1 Wednesday, September 27, 2006
Free weekly newspaper that includes business and classified advertising.
Date:
September 27, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 36, No. 612, Ed. 1 Friday, January 27, 2006
Free weekly newspaper that includes business and classified advertising.
Date:
January 27, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
[Email from Nell Bright, June 27, 2006]
Email from Nell Bright to the WASP board concerning an unnamed member's opposition to hiring an Executive Director.
Date:
June 27, 2006
Creator:
Bright, Nell
Object Type:
Letter
System:
The Portal to Texas History
[Email from Lucile Wise, June 27, 2006]
Email from Lucile Wise to the WASP board concerning the board's plan to hire an Executive Director. Wise proposes a compromise allowing the treasurer to maintain control over the organization's bank accounts.
Date:
June 27, 2006
Creator:
Wise, Lucile
Object Type:
Letter
System:
The Portal to Texas History