Cometary X-Rays: Line Emission Cross Sections for Multiply Charged Solar Wind Ion Charge Exchange (open access)

Cometary X-Rays: Line Emission Cross Sections for Multiply Charged Solar Wind Ion Charge Exchange

Absolute line emission cross sections are presented for 1 keV/amu charge exchange collisions of multiply charged solar wind ions with H{sub 2}O, H, O, CO{sub 2}, and CO cometary targets. The present calculations are contrasted with available laboratory data. A parameter-free model is used to successfully predict the recently observed x-ray spectra of comet C/LINEAR 1999 S4. We show that the resulting spectrum is extremely sensitive to the time variations of the solar wind composition. Our results suggest that orbiting x-ray satellites may be a viable way to predict the solar wind intensities and composition on the Earth many hours before the ions reach the earth.
Date: December 22, 2006
Creator: Otranto, S; Olson, R E & Beiersdorfer, P
Object Type: Article
System: The UNT Digital Library
Delineation of a Wellhead Protection Zone and Determination of Flowpaths From Potential Groundwater Contaminant Source Areas at Camp Ripley, Little Falls, Minnesota. (open access)

Delineation of a Wellhead Protection Zone and Determination of Flowpaths From Potential Groundwater Contaminant Source Areas at Camp Ripley, Little Falls, Minnesota.

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Date: December 22, 2006
Creator: Quinn, J. J. & Division, Environmental Science
Object Type: Report
System: The UNT Digital Library
Development of an Ultra-fine Coal Dewatering Technology and an Integrated Flotation-Dewatering System for Coal Preparation Plants (open access)

Development of an Ultra-fine Coal Dewatering Technology and an Integrated Flotation-Dewatering System for Coal Preparation Plants

The project proposal was approved for only the phase I period. The goal for this Phase I project was to develop an industrial model that can perform continuous and efficient dewatering of fine coal slurries of the previous flotation process to fine coal cake of {approx}15% water content from 50-70%. The feasibility of this model should be demonstrated experimentally using a lab scale setup. The Phase I project was originally for one year, from May 2005 to May 2006. With DOE approval, the project was extended to Dec. 2006 without additional cost from DOE to accomplish the work. Water has been used in mining for a number of purposes such as a carrier, washing liquid, dust-catching media, fire-retardation media, temperature-control media, and solvent. When coal is cleaned in wet-processing circuits, waste streams containing water, fine coal, and noncombustible particles (ash-forming minerals) are produced. In many coal preparation plants, the fine waste stream is fed into a series of selection processes where fine coal particles are recovered from the mixture to form diluted coal fine slurries. A dewatering process is then needed to reduce the water content to about 15%-20% so that the product is marketable. However, in the dewatering process …
Date: December 22, 2006
Creator: Zhang, Wu; Yang, David; Amarnath, Amar; Huq, Iftikhar; O'Brien, Scott & Williams, Jim
Object Type: Report
System: The UNT Digital Library
Equation of State, Occupation Probabilities and Conductivities in the Average Atom Purgatorio Code (open access)

Equation of State, Occupation Probabilities and Conductivities in the Average Atom Purgatorio Code

We report on recent developments with the Purgatorio code, a new implementation of Liberman's Inferno model. This fully relativistic average atom code uses phase shift tracking and an efficient refinement scheme to provide an accurate description of continuum states. The resulting equations of state accurately represent the atomic shell-related features which are absent in Thomas-Fermi-based approaches. We discuss various representations of the exchange potential and some of the ambiguities in the choice of the effective charge Z* in average atom models, both of which affect predictions of electrical conductivities and radiative properties.
Date: December 22, 2006
Creator: Sterne, P
Object Type: Article
System: The UNT Digital Library
Fluidized Bed Steam Reformer Monolith Formation (open access)

Fluidized Bed Steam Reformer Monolith Formation

Fluidized Bed Steam Reforming (FBSR) is being considered as an alternative technology for the immobilization of a wide variety of aqueous high sodium containing radioactive wastes at various DOE facilities in the United States. The addition of clay, charcoal, and a catalyst as co-reactants converts aqueous Low Activity Wastes (LAW) to a granular or ''mineralized'' waste form while converting organic components to CO{sub 2} and steam, and nitrate/nitrite components, if any, to N{sub 2}. The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage-like structures that atomically bond radionuclides like Tc-99 and anions such as SO{sub 4}, I, F, and Cl. The granular product has been shown to be as durable as LAW glass. Shallow land burial requires that the mineralized waste form be able to sustain the weight of soil overburden and potential intrusion by future generations. The strength requirement necessitates binding the granular product into a monolith. FBSR mineral products were formulated into a variety of monoliths including various cements, Ceramicrete, and hydroceramics. All but one of the nine monoliths tested met the <2g/m{sup 2} durability specification for Na and Re (simulant for Tc-99) when tested using the Product Consistency Test (PCT; …
Date: December 22, 2006
Creator: Jantzen, Carol M.
Object Type: Article
System: The UNT Digital Library
Non equilibrium dynamics of mixing, oscillations, and equilibration: A model study (open access)

Non equilibrium dynamics of mixing, oscillations, and equilibration: A model study

The non-equilibrium dynamics of mixing, oscillations and equilibration is studied in a field theory of flavored neutral mesons that effectively models two flavors of mixed neutrinos, in interaction with other mesons that represent a thermal bath of hadrons or quarks and charged leptons. This model describes the general features of neutrino mixing and relaxation via charged currents in a medium. The reduced density matrix and the non-equilibrium effective action that describes the propagation of neutrinos is obtained by integrating out the bath degrees of freedom. We obtain the dispersion relations, mixing angles and relaxation rates of ``neutrino'' quasiparticles. The dispersion relations and mixing angles are of the same form as those of neutrinos in the medium, and the relaxation rates are given by $\Gamma_1(k) = \Gamma_{ee}(k) \cos^2\theta_m(k)+\Gamma_{\mu\mu}(k)\sin^2\theta_m(k); \Gamma_2(k)= \Gamma_{\mu\mu}(k) \cos^2\theta_m(k)+\Gamma_{ee}(k)\sin^2\theta_m(k) $ where $\Gamma_{\alpha\alpha}(k)$ are the relaxation rates of the flavor fields in \emph{absence} of mixing, and $\theta_m(k)$ is the mixing angle in the medium. A Weisskopf-Wigner approximation that describes the asymptotic time evolution in terms of a non-hermitian Hamiltonian is derived. At long time $>>\Gamma^{-1}_{1,2}$ ``neutrinos'' equilibrate with the bath. The equilibrium density matrix is nearly diagonal in the basis of eigenstates of an \emph{effective Hamiltonian that includes self-energy corrections …
Date: December 22, 2006
Creator: Ho, Chiu Man; Boyanovsky, D. & Ho, C. M.
Object Type: Article
System: The UNT Digital Library
Removal of CDP Mandrels from Sputter Coated Beryllium Capsules for NIF Targets (open access)

Removal of CDP Mandrels from Sputter Coated Beryllium Capsules for NIF Targets

Ablative targets for the National Ignition Campaign (NIC) have been fabricated by sputter coating spherical mandrels made of glow discharge polymer (GDP) with graded copper doped beryllium (Be) layers. The inner mandrel must be completely removed to meet specific ignition design requirements. The process of removing the mandrel requires elevated temperature in the presence of oxygen. However, elevating the temperature in air also oxidizes the Be and can cause blistering on the inner surface of the Be shell. This paper will discuss a refined technique, which removes the GDP mandrel without compromising the integrity of the inner Be surface. The oxygen gradient that develops during the mandrel removal and the impact of its presence will also be discussed.
Date: December 22, 2006
Creator: Lawrence Livermore National Laboratory
Object Type: Article
System: The UNT Digital Library
Sensitivity Analysis of the DARHT-II 2.5MV/2kA Diode (open access)

Sensitivity Analysis of the DARHT-II 2.5MV/2kA Diode

This report summarizes the study of the tolerance limits on the assembly of the cathode and the Pierce electrode for the DARHT-II diode (2.5 MV, 2 kA case), performed through a series of computer simulations using the PIC code WARP [1]. We have considered sources of beam quality degradation like the errors in axial and transverse positioning, and the size of the radial gap between the cathode and the Pierce electrode (shroud). The figure of merit was chosen to be the RMS beam (edge) emittance at a distance of 1 meter from the cathode, as defined by {var_epsilon}{sub x} = 4 {beta}{gamma} {radical}(<x{sup 2}><x{prime}{sup 2}>-<xx{prime}>{sup 2}) {center_dot}. The analysis shows that to position the cathode at the correct axial and transverse location is more important than the size of the radial gap.
Date: December 22, 2006
Creator: Henestroza, Enrique
Object Type: Report
System: The UNT Digital Library
Uranium-lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201 (open access)

Uranium-lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201

Uranium-lead ratios (commonly represented as {sup 238}U/{sup 204}Pb = {mu}) calculated for the sources of martian basalts preserve a record of petrogenetic processes that operated during early planetary differentiation and formation of martian geochemical reservoirs. To better define the range of {mu} values represented by the source regions of martian basalts, we completed U-Pb elemental and isotopic analyses on whole rock, mineral and leachate fractions from the martian meteorite Queen Alexandra Range 94201 (QUE 94201). The whole rock and silicate mineral fractions have unradiogenic Pb isotopic compositions that define a narrow range ({sup 206}Pb/{sup 204}Pb = 11.16-11.61). In contrast, the Pb isotopic compositions of weak HCl leachates are more variable and radiogenic. The intersection of the QUE 94201 data array with terrestrial Pb in {sup 206}Pb/{sup 204}Pb-{sup 207}Pb/{sup 204}Pb-{sup 208}Pb/{sup 204}Pb compositional space is consistent with varying amounts of terrestrial contamination in these fractions. We calculate that only 1-7% contamination is present in the purified silicate mineral and whole rock fractions, whereas the HCl leachates contain up to 86% terrestrial contamination. Despite the contamination, we are able to use the U-Pb data to determine the initial {sup 206}Pb/{sup 204}Pb of QUE 94201 (11.086 {+-} 0.008) and calculate the {mu} value …
Date: December 22, 2006
Creator: Gaffney, A M; Borg, L E & Connelly, J N
Object Type: Article
System: The UNT Digital Library