From many body wee partons dynamics to perfect fluid: a standard model for heavy ion collisions (open access)

From many body wee partons dynamics to perfect fluid: a standard model for heavy ion collisions

We discuss a standard model of heavy ion collisions that has emerged both from experimental results of the RHIC program and associated theoretical developments. We comment briefly on the impact of early results of the LHC program on this picture. We consider how this standard model of heavy ion collisions could be solidified or falsified in future experiments at RHIC, the LHC and a future Electro-Ion Collider.
Date: July 22, 2010
Creator: Venugopalan, R.
Object Type: Article
System: The UNT Digital Library
Analysis of the National Ignition Facility Ignition Hohlraum Energetics Experiments (open access)

Analysis of the National Ignition Facility Ignition Hohlraum Energetics Experiments

A series of forty experiments on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] to study energy balance and implosion symmetry in reduced- and full-scale ignition hohlraums was shot at energies up to 1.3 MJ. This paper reports the findings of the analysis of the ensemble of experimental data obtained that has produced an improved model for simulating ignition hohlraums. Last year the first observation in a NIF hohlraum of energy transfer between cones of beams as a function of wavelength shift between those cones was reported [P. Michel, et al, Phys of Plasmas, 17, 056305, (2010)]. Detailed analysis of hohlraum wall emission as measured through the laser entrance hole (LEH) has allowed the amount of energy transferred versus wavelength shift to be quantified. The change in outer beam brightness is found to be quantitatively consistent with LASNEX [G. B. Zimmerman and W. L. Kruer, Comments Plasma Phys. Control. Fusion 2, 51 (1975)] simulations using the predicted energy transfer when possible saturation of the plasma wave mediating the transfer is included. The effect of the predicted energy transfer on implosion symmetry is also found to be in good agreement with gated x-ray framing …
Date: November 22, 2010
Creator: Town, R. J.; Rosen, M. D.; Michel, P. A.; Divol, L.; Moody, J. D.; Kyrala, G. A. et al.
Object Type: Article
System: The UNT Digital Library
A molecularly defined duplication set for the X chromosome of Drosophila melanogaster (open access)

A molecularly defined duplication set for the X chromosome of Drosophila melanogaster

We describe a molecularly defined duplication kit for the X chromosome of Drosophila melanogaster. A set of 408 overlapping P[acman] BAC clones was used to create small duplications (average length 88 kb) covering the 22-Mb sequenced portion of the chromosome. The BAC clones were inserted into an attP docking site on chromosome 3L using C31 integrase, allowing direct comparison of different transgenes. The insertions complement 92% of the essential and viable mutations and deletions tested, demonstrating that almost all Drosophila genes are compact and that the current annotations of the genome are reasonably accurate. Moreover, almost all genes are tolerated at twice the normal dosage. Finally, we more precisely mapped two regions at which duplications cause diplo-lethality in males. This collection comprises the first molecularly defined duplication set to cover a whole chromosome in a multicellular organism. The work presented removes a long-standing barrier to genetic analysis of the Drosophila X chromosome, will greatly facilitate functional assays of X-linked genes in vivo, and provides a model for functional analyses of entire chromosomes in other species.
Date: July 22, 2010
Creator: Venken, Koen J. T.; Popodi, Ellen; Holtzman, Stacy L.; Schulze, Karen L.; Park, Soo; Carlson, Joseph W. et al.
Object Type: Article
System: The UNT Digital Library
EVALUATION OF POTENTIAL ELUANTS FOR NON-ACID ELUTION OF CESIUM FROM RESORCINOL-FORMALDEHYDE RESIN (open access)

EVALUATION OF POTENTIAL ELUANTS FOR NON-ACID ELUTION OF CESIUM FROM RESORCINOL-FORMALDEHYDE RESIN

Small-column ion exchange (SCIX) units installed in high-level waste tanks to remove Cs-137 from highly alkaline salt solutions are among the waste treatment plans in the DOE-complex. Spherical Resorcinol-Formaldehyde (sRF) is the ion exchange resin selected for use in the Hanford Waste Treatment and Immobilization Plant (WTP). It is also the primary ion exchange material under consideration for SCIX at the Hanford site. The elution step of the multi-step ion exchange process is typically done with 0.5 M nitric acid. An acid eluant is a potential hazard in the event of a spill, leak, etc. because the high-level waste tanks are made of carbon steel. Corrosion and associated structural damage may ensue. A study has been conducted to explore non-acid elution as an alternative. Batch contact sorption equilibrium screening tests have been conducted with 36 potential non-acid eluants. The sorption tests involve equilibrating each cesium-containing eluant solution with the sRF resin for 48 hours at 25 C in a shaker oven. In the sorption tests, an eluant is deemed to have a high cesium elution potential if it minimizes cesium sorption onto the sRF resin. The top candidates (based on lowest cesium sorption distribution coefficients) include ammonium carbonate, ammonium carbonate/ammonium …
Date: December 22, 2010
Creator: Adu-Wusu, K. & Pennebaker, F.
Object Type: Report
System: The UNT Digital Library
Characterization of the Wymark CO2 Reservoir: A Natural Analog to Long-Term CO2 Storage at Weyburn (open access)

Characterization of the Wymark CO2 Reservoir: A Natural Analog to Long-Term CO2 Storage at Weyburn

Natural accumulations of CO{sub 2} occur in the Duperow and other Devonian strata on the western flank of the Williston Basin in lithologies very similar to those into which anthropogenic CO{sub 2} is being injected as part of an EOR program in the Weyburn-Midale pool. Previous workers have established the stratgraphic and petrographic similarities between the Duperow and Midale beds (Lake and Whittaker, 2004 and 2006). As the CO{sub 2} accumulations in the Devonian strata may be as old as 50 Ma, this similarity provides confidence in the efficacy of long-term geologic sequestration of CO{sub 2} in the Midale-Weyburn pool. Here we attempt to extend this comparison with whole rock and mineral chemistry using the same sample suite used by Lake and Whittaker. We provide XRD, XRF, and electron microprobe analysis of major constituent minerals along with extensive backscattered electron and x-ray imaging to identify trace phases and silicate minerals. LPNORM analysis is used to quantify modal concentrations of minerals species. Samples from depth intervals where CO{sub 2} has been observed are compared to those where CO{sub 2} was absent, with no systematic differences in mineral composition observed. Gas accumulation can be correlated with sample porosity. In particular gas-bearing samples …
Date: November 22, 2010
Creator: Ryerson, F & Johnson, J
Object Type: Report
System: The UNT Digital Library
A Proposal for User-defined Reductions in OpenMP (open access)

A Proposal for User-defined Reductions in OpenMP

Reductions are commonly used in parallel programs to produce a global result from partial results computed in parallel. Currently, OpenMP only supports reductions for primitive data types and a limited set of base language operators. This is a significant limitation for those applications that employ user-defined data types (e. g., objects). Implementing manual reduction algorithms makes software development more complex and error-prone. Additionally, an OpenMP runtime system cannot optimize a manual reduction algorithm in ways typically applied to reductions on primitive types. In this paper, we propose new mechanisms to allow the use of most pre-existing binary functions on user-defined data types as User-Defined Reduction (UDR) operators. Our measurements show that our UDR prototype implementation provides consistently good performance across a range of thread counts without increasing general runtime overheads.
Date: March 22, 2010
Creator: Duran, A; Ferrer, R; Klemm, M; de Supinski, B R & Ayguade, E
Object Type: Article
System: The UNT Digital Library
Trace Assessment for BWR ATWS Analysis (open access)

Trace Assessment for BWR ATWS Analysis

A TRACE/PARCS input model has been developed in order to be able to analyze anticipated transients without scram (ATWS) in a boiling water reactor. The model is based on one developed previously for the Browns Ferry reactor for doing loss-of-coolant accident analysis. This model was updated by adding the control systems needed for ATWS and a core model using PARCS. The control systems were based on models previously developed for the TRAC-B code. The PARCS model is based on information (e.g., exposure and moderator density (void) history distributions) obtained from General Electric Hitachi and cross sections for GE14 fuel obtained from an independent source. The model is able to calculate an ATWS, initiated by the closure of main steam isolation valves, with recirculation pump trip, water level control, injection of borated water from the standby liquid control system and actuation of the automatic depres-surization system. The model is not considered complete and recommendations are made on how it should be improved.
Date: April 22, 2010
Creator: Cheng, L. Y.; Diamond, D. & Arantxa Cuadra, Gilad Raitses, Arnold Aronson
Object Type: Report
System: The UNT Digital Library
Lead-Cooled Fast Reactor (LFR) Design: Safety, Neutronics, Thermal Hydraulics, Structural Mechanics, Fuel, Core, and Plant Design (open access)

Lead-Cooled Fast Reactor (LFR) Design: Safety, Neutronics, Thermal Hydraulics, Structural Mechanics, Fuel, Core, and Plant Design

Fifth chapter from "A Compendium of Reactor Technology" discussing the history and design of lead-cooled fast reactors in nine sections: Lead-cooled Fast Reactor (LFR) Development, Design Criteria and General Specifications, Neutronics, Lead Properties, Compatibility of Structural Materials with Lead, Core, Reactor System, Decay Heat Removal System, and Nuclear Island.
Date: February 22, 2010
Creator: Smith, Craig; Cinotti, L.; Artoli, C. & Grasso, G.
Object Type: Book Chapter
System: The UNT Digital Library
Summary Report for the Development of Materials for Volatile Radionuclides (open access)

Summary Report for the Development of Materials for Volatile Radionuclides

The materials development summarized here is in support of the Waste Forms campaign, Volatile Radionuclide task. Specifically, materials are being developed for the removal and immobilization of iodine and krypton, specifically 129I and 85Kr. During FY 2010, aerogel materials were investigated for removal and immobilization of 129I. Two aerogel formulations were investigated, one based on silica aerogels and the second on chalcogenides. For 85Kr, metal organic framework (MOF) structures were investigated.
Date: November 22, 2010
Creator: Strachan, Denis M.; Chun, Jaehun; Henager, Charles H.; Matyas, Josef; Riley, Brian J.; Ryan, Joseph V. et al.
Object Type: Report
System: The UNT Digital Library
In-Situ Real Time Monitoring and Control of Mold Making and Filling Processes: Final Report (open access)

In-Situ Real Time Monitoring and Control of Mold Making and Filling Processes: Final Report

This project presents a model for addressing several objectives envisioned by the metal casting industries through the integration of research and educational components. It provides an innovative approach to introduce technologies for real time characterization of sand molds, lost foam patterns and monitoring of the mold filling process. The technology developed will enable better control over the casting process. It is expected to reduce scrap and variance in the casting quality. A strong educational component is integrated into the research plan to utilize increased awareness of the industry professional, the potential benefits of the developed technology, and the potential benefits of cross cutting technologies.
Date: December 22, 2010
Creator: Abdelrahman, Mohamed & Currie, Kenneth
Object Type: Report
System: The UNT Digital Library
Development of Extruded Scintillator and Single-Bit Tracking Calorimetry - Final Report (open access)

Development of Extruded Scintillator and Single-Bit Tracking Calorimetry - Final Report

Final Closeout report for DE-FG02-02ER41223
Date: June 22, 2010
Creator: Chakraborty, Dhiman
Object Type: Report
System: The UNT Digital Library
Comparison of the Wymark CO2 Reservoir with the Midale Beds at the Weyburn CO2 Injection Project (open access)

Comparison of the Wymark CO2 Reservoir with the Midale Beds at the Weyburn CO2 Injection Project

The Devonian carbonates of the Duperow Formation on the western flank of the Williston Basin in southwest Saskatchewan contain natural accumulations of CO{sub 2}, and may have done so for as long as 50 m.y. in the views of some investigations. These carbonate sediments are characterized by a succession of carbonate cycles capped by anhydrite-rich evaporites that are thought to act as seals to fluid migration. The Weyburn CO{sub 2} injection site lies 400 km to the east in a series of Mississippian carbonates that were deposited in a similar depositional environment. That natural CO{sub 2} can be stored long-term within carbonate strata has motivated the investigation of the Duperow rocks as a potential natural analogue to storage of anthropogenic CO{sub 2} that may ultimately provide additional confidence for CO{sub 2} sequestration in carbonate lithologies. For the Duperow strata to represent a legitimate analog for Midale injection and storage, the similarity in lithofacies, whole rock compositions, mineral compositions and porosity with the Midale Beds must be established. Previous workers have demonstrated the similarity of the lithofacies at both sites. Here we compare the whole rock compositions, mineralogy and mineral compositions. The major mineral phases at both locales are calcite, dolomite …
Date: November 22, 2010
Creator: Ryerson, F & Johnson, J
Object Type: Report
System: The UNT Digital Library
Microchannel Reactor System for Catalytic Hydrogenation (open access)

Microchannel Reactor System for Catalytic Hydrogenation

We successfully demonstrated a novel process intensification concept enabled by the development of microchannel reactors, for energy efficient catalytic hydrogenation reactions at moderate temperature, and pressure, and low solvent levels. We designed, fabricated, evaluated, and optimized a laboratory-scale microchannel reactor system for hydrogenation of onitroanisole and a proprietary BMS molecule. In the second phase of the program, as a prelude to full-scale commercialization, we designed and developed a fully-automated skid-mounted multichannel microreactor pilot plant system for multiphase reactions. The system is capable of processing 1 – 10 kg/h of liquid substrate, and an industrially relevant immiscible liquid-liquid was successfully demonstrated on the system. Our microreactor-based pilot plant is one-of-akind. We anticipate that this process intensification concept, if successfully demonstrated, will provide a paradigm-changing basis for replacing existing energy inefficient, cost ineffective, environmentally detrimental slurry semi-batch reactor-based manufacturing practiced in the pharmaceutical and fine chemicals industries.
Date: December 22, 2010
Creator: Lawal, Adeniyi; Lee, Woo; Besser, Ron; Kientzler, Donald & Achenie, Luke
Object Type: Report
System: The UNT Digital Library
MEASUREMENTS OF PAST 14C LEVELS AND 13C/12C RATIOS IN THE SURFACE WATERS OF THE WORLD'S SUBPOLAR OCEANS. (open access)

MEASUREMENTS OF PAST 14C LEVELS AND 13C/12C RATIOS IN THE SURFACE WATERS OF THE WORLD'S SUBPOLAR OCEANS.

Under this project we have developed methods that allow the reconstruction of past {sup 14}C levels of the surface waters of the subpolar North Pacific Ocean by measuring the {sup 14}C contents of archived salmon scales. The overall goal of this research was to reduce of the uncertainty in the uptake of fossil CO{sub 2} by the oceans and thereby improve the quantification of the global carbon cycle and to elucidate the fate of anthropogenic CO{sub 2}. Ocean General Circulation Models (OGCMs), with their three dimensional global spatial coverage and temporal modeling capabilities, provide the best route to accurately calculating the total uptake of CO{sub 2} by the oceans and, hence, to achieving the desired reduction in uncertainty. {sup 14}C has played, and continues to play, a central role in the validation of the OGCMs calculations, particularly with respect to those model components which govern the uptake of CO{sub 2} from the atmosphere and the transport of this carbon within the oceans. Under this project, we have developed time-series records of the {sup 14}C levels of the surface waters of three areas of the subpolar North Pacific Ocean. As the previously available data on the time-history of oceanic surface water …
Date: April 22, 2010
Creator: Brown, T A
Object Type: Report
System: The UNT Digital Library
PRELIMINARY STUDY OF CERAMICS FOR IMMOBILIZATION OF ADVANCED FUEL CYCLE REPROCESSING WASTES (open access)

PRELIMINARY STUDY OF CERAMICS FOR IMMOBILIZATION OF ADVANCED FUEL CYCLE REPROCESSING WASTES

The Savannah River National Laboratory (SRNL) developed a series of ceramic waste forms for the immobilization of Cesium/Lanthanide (CS/LN) and Cesium/Lanthanide/Transition Metal (CS/LN/TM) waste streams anticipated to result from nuclear fuel reprocessing. Simple raw materials, including Al{sub 2}O{sub 3}, CaO, and TiO{sub 2} were combined with simulated waste components to produce multiphase ceramics containing hollandite-type phases, perovskites (particularly BaTiO{sub 3}), pyrochlores, zirconolite, and other minor metal titanate phases. Identification of excess Al{sub 2}O{sub 3} via X-ray Diffraction (XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) in the first series of compositions led to a Phase II study, with significantly reduced Al{sub 2}O{sub 3} concentrations and increased waste loadings. Three fabrication methodologies were used, including melting and crystallizing, pressing and sintering, and Spark Plasma Sintering (SPS), with the intent of studying phase evolution under various sintering conditions. XRD and SEM/EDS results showed that the partitioning of the waste elements in the sintered materials was very similar, despite varying stoichiometry of the phases formed. The Phase II compositions generally contained a reduced amount of unreacted Al{sub 2}O{sub 3} as identified by XRD, and had phase assemblages that were closer to the initial targets. Chemical composition measurements showed no significant issues …
Date: September 22, 2010
Creator: Fox, K.; Billings, A.; Brinkman, K. & Marra, J.
Object Type: Report
System: The UNT Digital Library

Overview of the PV Module Model in PVWatts

Overview of the PV module model. PVWatts module power estimates were compared with those using the Sandia model for three modules and data sets.
Date: September 22, 2010
Creator: Marion, B.
Object Type: Presentation
System: The UNT Digital Library
A Piecewise Bi-Linear Discontinuous Finite Element Spatial Discretization of the Sn Transport Equation (open access)

A Piecewise Bi-Linear Discontinuous Finite Element Spatial Discretization of the Sn Transport Equation

We present a new spatial discretization of the discrete-ordinates transport equation in two-dimensional Cartesian (X-Y) geometry for arbitrary polygonal meshes. The discretization is a discontinuous finite element method (DFEM) that utilizes piecewise bi-linear (PWBL) basis functions, which are formally introduced in this paper. We also present a series of numerical results on quadrilateral and polygonal grids and compare these results to a variety of other spatial discretizations that have been shown to be successful on these grid types. Finally, we note that the properties of the PWBL basis functions are such that the leading-order piecewise bi-linear discontinuous finite element (PWBLD) solution will satisfy a reasonably accurate diffusion discretization in the thick diffusion limit, making the PWBLD method a viable candidate for many different classes of transport problems.
Date: December 22, 2010
Creator: Bailey, T S; Chang, J H; Warsa, J S & Adams, M L
Object Type: Article
System: The UNT Digital Library
Drilling and Production Testing the Methane Hydrate Resource Potential Associated with the Barrow Gas Fields (open access)

Drilling and Production Testing the Methane Hydrate Resource Potential Associated with the Barrow Gas Fields

In November of 2008, the Department of Energy (DOE) and the North Slope Borough (NSB) committed funding to develop a drilling plan to test the presence of hydrates in the producing formation of at least one of the Barrow Gas Fields, and to develop a production surveillance plan to monitor the behavior of hydrates as dissociation occurs. This drilling and surveillance plan was supported by earlier studies in Phase 1 of the project, including hydrate stability zone modeling, material balance modeling, and full-field history-matched reservoir simulation, all of which support the presence of methane hydrate in association with the Barrow Gas Fields. This Phase 2 of the project, conducted over the past twelve months focused on selecting an optimal location for a hydrate test well; design of a logistics, drilling, completion and testing plan; and estimating costs for the activities. As originally proposed, the project was anticipated to benefit from industry activity in northwest Alaska, with opportunities to share equipment, personnel, services and mobilization and demobilization costs with one of the then-active exploration operators. The activity level dropped off, and this benefit evaporated, although plans for drilling of development wells in the BGF's matured, offering significant synergies and cost savings …
Date: February 22, 2010
Creator: McRae, Steve; Walsh, Thomas; Dunn, Michael & Cook, Michael
Object Type: Report
System: The UNT Digital Library
Edge Plasma Boundary Layer Generated By Kink Modes in Tokamaks (open access)

Edge Plasma Boundary Layer Generated By Kink Modes in Tokamaks

This paper describes the structure of the electric current generated by external kink modes at the plasma edge using the ideally conducting plasma model. It is found that the edge current layer is created by both wall touching and free boundary kink modes. Near marginal stability, the total edge current has a universal expression as a result of partial compensation of the δ-functional surface current by the bulk current at the edge. The resolution of an apparent paradox with the pressure balance across the plasma boundary in the presence of the surface currents is provided.
Date: November 22, 2010
Creator: Zakharov, L.E.
Object Type: Report
System: The UNT Digital Library
SINGLE-SHELL TANK INTEGRITY PROJECT ANALYSIS OF RECORD-PRELIMINARY MODELING PLAN FOR THERMAL AND OPERATING LOADS (open access)

SINGLE-SHELL TANK INTEGRITY PROJECT ANALYSIS OF RECORD-PRELIMINARY MODELING PLAN FOR THERMAL AND OPERATING LOADS

This document is a Phase I deliverable for the Single-Shell Tank Analysis of Record effort. This document is not the Analysis of Record. The intent of this document is to guide the Phase II detailed modeling effort. Preliminary finite element models for each of the tank types were developed and different case studies were performed on one or more of these tank types. Case studies evaluated include thermal loading, waste level variation, the sensitivity of boundary effects (soil radial extent), excavation slope or run to rise ratio, soil stratigraphic (property and layer thickness) variation at different farm locations, and concrete material property variation and their degradation under thermal loads. The preliminary analysis document reviews and preliminary modeling analysis results are reported herein. In addition, this report provides recommendations for the next phase of the SST AOR project, SST detailed modeling. Efforts and results discussed in this report do not include seismic modeling as seismic modeling is covered by a separate report. The combined results of both static and seismic models are required to complete this effort. The SST AOR project supports the US Department of Energy's (DOE) Office of River Protection (ORP) mission for obtaining a better understanding of the …
Date: October 22, 2010
Creator: RS, RAST; MW, RINKER; SK, BAPANAALLI; JE, DEIBLER; CE, GUZMAN-LEONG; KI, JOHNSON et al.
Object Type: Report
System: The UNT Digital Library
Statistical Exploration of Electronic Structure of Molecules from Quantum Monte-Carlo Simulations (open access)

Statistical Exploration of Electronic Structure of Molecules from Quantum Monte-Carlo Simulations

In this report, we present results from analysis of Quantum Monte Carlo (QMC) simulation data with the goal of determining internal structure of a 3N-dimensional phase space of an N-electron molecule. We are interested in mining the simulation data for patterns that might be indicative of the bond rearrangement as molecules change electronic states. We examined simulation output that tracks the positions of two coupled electrons in the singlet and triplet states of an H2 molecule. The electrons trace out a trajectory, which was analyzed with a number of statistical techniques. This project was intended to address the following scientific questions: (1) Do high-dimensional phase spaces characterizing electronic structure of molecules tend to cluster in any natural way? Do we see a change in clustering patterns as we explore different electronic states of the same molecule? (2) Since it is hard to understand the high-dimensional space of trajectories, can we project these trajectories to a lower dimensional subspace to gain a better understanding of patterns? (3) Do trajectories inherently lie in a lower-dimensional manifold? Can we recover that manifold? After extensive statistical analysis, we are now in a better position to respond to these questions. (1) We definitely see clustering …
Date: December 22, 2010
Creator: Prabhat, Mr.; Zubarev, Dmitry & Lester, William A., Jr.
Object Type: Report
System: The UNT Digital Library
Intermittency in the Scrape-off Layer of the National Spherical Torus Experiment During H-mode Confinement (open access)

Intermittency in the Scrape-off Layer of the National Spherical Torus Experiment During H-mode Confinement

A gas puff imaging diagnostic is used in the National Spherical Tokamak Experiment [M. Ono, et al., Nucl. Fusion 40, 557 (2000)] to study the edge turbulence and intermittency present during H-mode discharges. In the case of low power Ohmic H-modes the suppression of turbulence/blobs is maintained through the duration of the (short lived) H-modes. Similar quiescent edges are seen during the early stages of H-modes created with the use of neutral beam injection. Nevertheless, as time progresses following the L-H transition, turbulence and blobs reappear although at a lower level than that typically seen during L-mode confinement. It is also seen that the time-averaged SOL emission profile broadens, as the power loss across the separatrix increases. These broad profiles are characterized by a large level of fluctuations and intermittent events.
Date: November 22, 2010
Creator: Maqueda, R. J.; Stotler, D. P. & Zweben, S. J.
Object Type: Report
System: The UNT Digital Library
The Influence of Linker Geometry on Uranyl Complexation by Rigidly-Linked Bis(3-hydroxy-N-methyl-pyridin-2-one) (open access)

The Influence of Linker Geometry on Uranyl Complexation by Rigidly-Linked Bis(3-hydroxy-N-methyl-pyridin-2-one)

A series of bis(3-hydroxy-N-methyl-pyridin-2-one) ligands was synthesized, and their respective uranyl complexes were characterized by single crystal X-ray diffraction analyses. These structures were inspected for high-energy conformations and evaluated using a series of metrics to measure co-planarity of chelating moieties with each other and the uranyl coordination plane, as well as to measure coordinative crowding about the uranyl dication. Both very short (ethyl, 3,4-thiophene and o-phenylene) and very long ({alpha},{alpha}{prime}-m-xylene and 1,8-fluorene) linkers provide optimal ligand geometries about the uranyl cation, resulting in planar, unstrained molecular arrangements. The planarity of the rigid linkers also suggests there is a degree of pre-organization for a planar coordination mode that is ideal for uranyl-selective ligand design. Comparison of intramolecular N{sub amide}-O{sub phenolate} distances and {sup 1}H NMR chemical shifts of amide protons supports earlier results that short linkers provide the optimal geometry for intramolecular hydrogen bonding.
Date: April 22, 2010
Creator: Szigethy, Geza & Raymond, Kenneth
Object Type: Article
System: The UNT Digital Library
Epithermal Neutron Source for Neutron Resonance Spectroscopy (NRS) using High Intensity, Short Pulse Lasers (open access)

Epithermal Neutron Source for Neutron Resonance Spectroscopy (NRS) using High Intensity, Short Pulse Lasers

A neutron source for neutron resonance spectroscopy (NRS) has been developed using high intensity, short pulse lasers. This measurement technique will allow for robust measurements of interior ion temperature of laser-shocked materials and provide insight into equation of state (EOS) measurements. The neutron generation technique uses protons accelerated by lasers off of Cu foils to create neutrons in LiF, through (p,n) reactions with {sup 7}Li and {sup 19}F. The distribution of the incident proton beam has been diagnosed using radiochromic film (RCF). This distribution is used as the input for a (p,n) neturon prediction code which is compared to experimentally measured neutron yields. From this calculation, a total fluence of 1.8 x 10{sup 9} neutrons is infered, which is shown to be a reasonable amount for NRS temperature measurement.
Date: April 22, 2010
Creator: Higginson, D. P.; McNaney, J. M.; Swift, D. C.; Bartal, T.; Hey, D. S.; Pape, S. L. et al.
Object Type: Article
System: The UNT Digital Library