Accelerator Mass Spectrometry Measurements of Plutonium in Sediment and Seawater from the Marshall Islands (open access)

Accelerator Mass Spectrometry Measurements of Plutonium in Sediment and Seawater from the Marshall Islands

During the summer 2000, I was given the opportunity to work for about three months as a technical trainee at Lawrence Livermore National Laboratory, or LLNL as I will refer to it hereafter. University of California runs this Department of Energy laboratory, which is located 70 km east of San Francisco, in the small city of Livermore. This master thesis in Radioecology is based on the work I did here. LLNL, as a second U.S.-facility for development of nuclear weapons, was built in Livermore in the beginning of the 1950's (Los Alamos in New Mexico was the other one). It has since then also become a 'science center' for a number of areas like magnetic and laser fusion energy, non-nuclear energy, biomedicine, and environmental science. The Laboratory's mission has changed over the years to meet new national needs. The following two statements were found on the homepage of LLNL (http://www.llnl.gov), at 2001-03-05, where also information about the laboratory and the scientific projects that takes place there, can be found. 'Our primary mission is to ensure that the nation's nuclear weapons remain safe, secure, and reliable and to prevent the spread and use of nuclear weapons worldwide'. 'Our goal is to …
Date: August 1, 2001
Creator: Leisvik, M & Hamilton, T
System: The UNT Digital Library
Application of the Scenario Planning Process - a Case Study: The Technical Information Department at the Lawrence Livermore National Laboratory (open access)

Application of the Scenario Planning Process - a Case Study: The Technical Information Department at the Lawrence Livermore National Laboratory

When the field of modern publishing was on a collision course with telecommunications, publishing organizations had to come up to speed in fields that were, heretofore, completely foreign and technologically forbidding to them. For generations, the technology of publishing centered on offset lithography, typesetting, and photography--fields that saw evolutionary and incremental change from the time of Guttenberg. But publishing now includes making information available over the World Wide Web--Internet publishing--with its ever-accelerating rate of technological change and dependence on computers and networks. Clearly, we need a methodology to help anyone in the field of Internet publishing plan for the future, and there is a well-known, well-tested technique for just this purpose--Scenario Planning. Scenario Planning is an excellent tool to help organizations make better decisions in the present based on what they identify as possible and plausible scenarios of the future. Never was decision making more difficult or more crucial than during the years of this study, 1996-1999. This thesis takes the position that, by applying Scenario Planning, the Technical Information Department at LLNL, a large government laboratory (and organizations similar to it), could be confident that moving into the telecommunications business of Internet publishing stood a very good chance of …
Date: November 26, 2001
Creator: Schuster, J A
System: The UNT Digital Library
Collisionless relaxation in beam-plasma systems (open access)

Collisionless relaxation in beam-plasma systems

This thesis reports the results from the theoretical investigations, both numerical and analytical, of collisionless relaxation phenomena in beam-plasma systems. Many results of this work can also be applied to other lossless systems of plasma physics, beam physics and astrophysics. Different aspects of the physics of collisionless relaxation and its modeling are addressed. A new theoretical framework, named Coupled Moment Equations (CME), is derived and used in numerical and analytical studies of the relaxation of second order moments such as beam size and emittance oscillations. This technique extends the well-known envelope equation formalism, and it can be applied to general systems with nonlinear forces. It is based on a systematic moment expansion of the Vlasov equation. In contrast to the envelope equation, which is derived assuming constant rms beam emittance, the CME model allows the emittance to vary through coupling to higher order moments. The CME model is implemented in slab geometry in the absence of return currents. The CME simulation yields rms beam sizes, velocity spreads and emittances that are in good agreement with particle-in-cell (PIC) simulations for a wide range of system parameters. The mechanism of relaxation is also considered within the framework of the CME system. It …
Date: May 1, 2001
Creator: Backhaus, Ekaterina Yu.
System: The UNT Digital Library
The Development of Layered Photonic Band Gap Structures Using a Micro-Transfer Molding Technique (open access)

The Development of Layered Photonic Band Gap Structures Using a Micro-Transfer Molding Technique

Photonic band gap (PBG) crystals are periodic dielectric structures that manipulate electromagnetic radiation in a manner similar to semiconductor devices manipulating electrons. Whereas a semiconductor material exhibits an electronic band gap in which electrons cannot exist, similarly, a photonic crystal containing a photonic band gap does not allow the propagation of specific frequencies of electromagnetic radiation. This phenomenon results from the destructive Bragg diffraction interference that a wave propagating at a specific frequency will experience because of the periodic change in dielectric permitivity. This gives rise to a variety of optical applications for improving the efficiency and effectiveness of opto-electronic devices. These applications are reviewed later. Several methods are currently used to fabricate photonic crystals, which are also discussed in detail. This research involves a layer-by-layer micro-transfer molding ({mu}TM) and stacking method to create three-dimensional FCC structures of epoxy or titania. The structures, once reduced significantly in size can be infiltrated with an organic gain media and stacked on a semiconductor to improve the efficiency of an electronically pumped light-emitting diode. Photonic band gap structures have been proven to effectively create a band gap for certain frequencies of electro-magnetic radiation in the microwave and near-infrared ranges. The objective of this …
Date: May 1, 2001
Creator: Sutherland, Kevin Jerome
System: The UNT Digital Library
The Development of Layered Photonic Band Gap Structures Using a Micro-Transfer Molding Technique (open access)

The Development of Layered Photonic Band Gap Structures Using a Micro-Transfer Molding Technique

Over the last ten years, photonic band gap (PBG) theory and technology have become an important area of research because of the numerous possible applications ranging from high-efficiency laser diodes to optical circuitry. This research concentrates on reducing the length scale in the fabrication of layered photonic band gap structures and developing procedures to improve processing consistency. Various procedures and materials have been used in the fabrication of layered PBG structures. This research focused on an economical micro transfer molding approach to create the final PBG structure. A poly dimethylsiloxane (PDMS) rubber mold was created from a silicon substrate. It was filled with epoxy and built layer-by-layer to create a 3-D epoxy structure. This structure was infiltrated with nanoparticle titania or a titania sol-gel, then fired to remove the polymer mold, leaving a monolithic ceramic inverse of the epoxy structure. The final result was a lattice of titania rolds that resembles a face-centered tetragonal structure. The original intent of this research was to miniaturize this process to a bar size small enough to create a photonic band gap for wavelengths of visible electro-magnetic radiation. The factor limiting progress was the absence of a silicon master mold of small enough dimensions. …
Date: June 27, 2001
Creator: Sutherland, Kevin Jerome
System: The UNT Digital Library
Drift compression and final focus systems for heavy ion inertial fusion (open access)

Drift compression and final focus systems for heavy ion inertial fusion

Longitudinal compression of space-charge dominated beams can be achieved by imposing a head-to-tail velocity tilt on the beam. This tilt has to be carefully tailored, such that it is removed by the longitudinal space-charge repulsion by the time the beam reaches the end of the drift compression section. The transverse focusing lattice should be designed such that all parts of the beam stay approximately matched, while the beam smoothly expands transversely to the larger beam radius needed in the final focus system following drift compression. In this thesis, several drift compression systems were designed within these constraints, based on a given desired pulse shape at the end of drift compression systems were designed within these constraints, based on a given desired pulse shape at the end of drift compression. The occurrence of mismatches due to a rapidly increasing current was analyzed. In addition, the sensitivity of drift compression to errors in the initial velocity tilt and current profile was studied. These calculations were done using a new computer code that accurately calculates the longitudinal electric field in the space-charge dominated regime.
Date: May 1, 2001
Creator: de Hoon, M.J.L.
System: The UNT Digital Library
Dualities in M-theory and Born-Infeld Theory (open access)

Dualities in M-theory and Born-Infeld Theory

We discuss two examples of duality. The first arises in the context of toroidal compactification of the discrete light cone quantization of M-theory. In the presence of nontrivial moduli coming from the M-theory three form, it has been conjectured that the system is described by supersymmetric Yang-Mills gauge theory on a noncommutative torus. We are able to provide evidence for this conjecture, by showing that the dualities of this M-theory compactification, which correspond to T-duality in Type IIA string theory, are also dualities of the noncommutative supersymmetric Yang-Mills description. One can also consider this as evidence for the accuracy of the Matrix Theory description of M-theory in this background. The second type of duality is the self-duality of theories with U(1) gauge fields. After discussing the general theory of duality invariance for theories with complex gauge fields, we are able to find a generalization of the well known U(1) Born-Infeld theory that contains any number of gauge fields and which is invariant under the maximal duality group. We then find a supersymmetric extension of our results, and also show that our results can be extended to find Born-Infeld type actions in any even dimensional spacetime.
Date: August 1, 2001
Creator: Brace, Daniel, M
System: The UNT Digital Library
Effect of surface structure on catalytic reactions: A sum frequency generation surface vibrational spectroscopy study (open access)

Effect of surface structure on catalytic reactions: A sum frequency generation surface vibrational spectroscopy study

In the results discussed above, it is clear that Sum Frequency Generation (SFG) is a unique tool that allows the detection of vibrational spectra of adsorbed molecules present on single crystal surfaces under catalytic reaction conditions. Not only is it possible to detect active surface intermediates, it is also possible to detect spectator species which are not responsible for the measured turnover rates. By correlating high-pressure SFG spectra under reaction conditions and gas chromatography (GC) kinetic data, it is possible to determine which species are important under reaction intermediates. Because of the flexibility of this technique for studying surface intermediates, it is possible to determine how the structures of single crystal surfaces affect the observed rates of catalytic reactions. As an example of a structure insensitive reaction, ethylene hydrogenation was explored on both Pt(111) and Pt(100). The rates were determined to be essentially the same. It was observed that both ethylidyne and di-{sigma} bonded ethylene were present on the surface under reaction conditions on both crystals, although in different concentrations. This result shows that these two species are not responsible for the measured turnover rate, as it would be expected that one of the two crystals would be more active …
Date: September 7, 2001
Creator: McCrea, Keith R.
System: The UNT Digital Library
Electroproduction DE Photons ET DE Pions Sur Le Proton AU Quadrimoment DE Transfert Q{Sup 2} = 1.0 Gev{Sup 2} (open access)

Electroproduction DE Photons ET DE Pions Sur Le Proton AU Quadrimoment DE Transfert Q{Sup 2} = 1.0 Gev{Sup 2}

Thesis on the virtual compton scattering experiment in Hall A at Jefferson Lab.
Date: November 1, 2001
Creator: Laveissiere, Geraud
System: The UNT Digital Library
Electroproduction of Photons and of Pawns on the Proton in Quadrimoment of Transfer Q2=1.0GeV2. Measure Cross Sections and Extraction of Polarizabilities Generalities; Electroproduction de Photons et de Pions sur le Proton au Quadrimoment de Transfert Q2=1.0GeV2. Mesure des Sections Efficaces et Extraction des Polarisabilites Generalisees (open access)

Electroproduction of Photons and of Pawns on the Proton in Quadrimoment of Transfer Q2=1.0GeV2. Measure Cross Sections and Extraction of Polarizabilities Generalities; Electroproduction de Photons et de Pions sur le Proton au Quadrimoment de Transfert Q2=1.0GeV2. Mesure des Sections Efficaces et Extraction des Polarisabilites Generalisees

In hadronic physics, the nucleon structure and the quarks confinement are still topical issues. The neutral pion electroproduction and virtual Compton scattering (VCS) reactions allow us to access new observables that describe this structure. This work is focused on the VCS experiment performed at Jefferson Lab in 1998.
Date: November 6, 2001
Creator: Laveissiere, Geraud
System: The UNT Digital Library
Estimation of fracture porosity in an unsaturated fractured welded tuff using gas tracer testing (open access)

Estimation of fracture porosity in an unsaturated fractured welded tuff using gas tracer testing

None
Date: October 1, 2001
Creator: Freifeld, Barry
System: The UNT Digital Library
Evaluation of chiller modeling approaches and their usability for fault detection (open access)

Evaluation of chiller modeling approaches and their usability for fault detection

Selecting the model is an important and essential step in model based fault detection and diagnosis (FDD). Several factors must be considered in model evaluation, including accuracy, training data requirements, calibration effort, generality, and computational requirements. All modeling approaches fall somewhere between pure first-principles models, and empirical models. The objective of this study was to evaluate different modeling approaches for their applicability to model based FDD of vapor compression air conditioning units, which are commonly known as chillers. Three different models were studied: two are based on first-principles and the third is empirical in nature. The first-principles models are the Gordon and Ng Universal Chiller model (2nd generation), and a modified version of the ASHRAE Primary Toolkit model, which are both based on first principles. The DOE-2 chiller model as implemented in CoolTools{trademark} was selected for the empirical category. The models were compared in terms of their ability to reproduce the observed performance of an older chiller operating in a commercial building, and a newer chiller in a laboratory. The DOE-2 and Gordon-Ng models were calibrated by linear regression, while a direct-search method was used to calibrate the Toolkit model. The ''CoolTools'' package contains a library of calibrated DOE-2 curves …
Date: May 1, 2001
Creator: Sreedharan, Priya
System: The UNT Digital Library
Fast methods for static Hamilton-Jacobi Partial Differential Equations (open access)

Fast methods for static Hamilton-Jacobi Partial Differential Equations

The authors develop a family of fast methods approximating the solution to a wide class of static Hamilton-Jacobi partial differential equations. These partial differential equations are considered in the context of control-theoretic and front-propagation problems. In general, to produce a numerical solution to such a problem, one has to solve a large system of coupled non-linear discretized equations. The techniques use partial information about the characteristic directions to de-couple the system. Previously known fast methods, available for isotropic problems, are discussed in detail. They introduce a family of new Ordered Upwinding Methods (OUM) for general (anisotropic) problems and prove convergence to the viscosity solution of the corresponding Hamilton-Jacobi partial differential equation. The hybrid methods introduced here are based on the analysis of the role played by anisotropy in the context of front propagation and optimal trajectory problems. The performance of the methods is analyzed and compared to that of several other numerical approaches to these problems. Computational experiments are performed using test problems from control theory, computational geometry and seismology.
Date: May 1, 2001
Creator: Vladimirsky, Alexander Boris
System: The UNT Digital Library
Focus on NIF May 2001 (open access)

Focus on NIF May 2001

The National Ignition Facility, a stadium-size, 192-beam laser, is an essential tool for maintaining the safety and reliability of our nuclear weapons, harnessing fusion energy for future generations, and unlocking the origins of the universe. In the FY2001 Energy and Water Appropriations Act (FPN00-48), Congress appropriated $199.1 million for the continued construction of NIF. Immediately, $130 million became available. After March 31, 2001, $69.1 million was to be made available only after Department of Energy certification to Congress regarding six specific points: (1) recommend an appropriate path forward for the project; (2) certify that all established project and scientific milestones are on schedule and cost; (3) conduct 1st and 2nd quarter project reviews in FY01 and determine the project is on schedule and cost; (4) study alternatives to a 192-beam ignition facility for the stockpile stewardship program (SSP); (5) implement an integrated cost-schedule earned-value project control system; and (6) create a five-year budget plan for the SSP.
Date: May 1, 2001
Creator: Warner, B
System: The UNT Digital Library
Focus on NIF September 2001 (open access)

Focus on NIF September 2001

As of the end of August, the National Ignition Facility (NIF) is satisfactorily meeting its technical performance, cost and schedule milestones. Hensel Phelps Construction Company (HPCC) turned over the Laser Building to the Beampath Infrastructure System (BIS) Commissioning and Operations team for beneficial occupancy.
Date: September 5, 2001
Creator: Warner, B
System: The UNT Digital Library
From First Principles: The Application of Quantum Mechanics to Complex Molecules and Solvated Systems (open access)

From First Principles: The Application of Quantum Mechanics to Complex Molecules and Solvated Systems

None
Date: December 31, 2001
Creator: Freitag, Mark A.
System: The UNT Digital Library
Geographical and Temporal Dynamics of Chaetocnema Pulicaria and Their Role in Stewart's Disease of Corn in Iowa (open access)

Geographical and Temporal Dynamics of Chaetocnema Pulicaria and Their Role in Stewart's Disease of Corn in Iowa

This thesis investigated the biology and importance of the corn flea beetle vector and its role in the Stewart's disease of corn pathosystem. This was accomplished by determining the number of corn flea beetle generations that occur in Iowa and by quantifying the proportions of those populations found to be infested with the causal agent of Stewart's disease, pantoea stewartii. In addition, a preliminary study was conducted to determine how soil temperature was influenced by air temperature and how this may be applied to forecasting for Stewart's disease of corn. Research using yellow sticky cards and sweep netting demonstrated that there are overwintering, first, and second field generations of the corn flea beetle in Iowa. It was also observed that there was a period during June of both 1999 and 2000 when corn flea beetles were not found, which is important new management information. This research has also demonstrated that the incidence of P. stewartii-infested corn flea beetles can be monitored by ELISA testing and that the incidence fluctuates greatly throughout the corn growing season. The initial level of inoculum (P. stewartii-infested corn flea beetles in the adult overwintering generation) does not remain static during the spring as was previously …
Date: May 27, 2001
Creator: Esker, Paul David
System: The UNT Digital Library
Geographical and Temporal Dynamics of Chaetocnema Pulicaria Populations and Their Role in Stewart's Disease of Corn in Iowa (open access)

Geographical and Temporal Dynamics of Chaetocnema Pulicaria Populations and Their Role in Stewart's Disease of Corn in Iowa

This thesis is organized into five chapters. Chapter 1 is the introduction and justification, chapters 2 and 3 are journal papers, chapter 4 is a preliminary analysis of winter environmental variables and their use in forecasting for Stewart's disease of corn, and chapter 5 is general conclusions and discussion. References can be found at the end of each chapter, except chapter 5 and are specific to that chapter.
Date: May 1, 2001
Creator: Esker, Paul David
System: The UNT Digital Library
High Precision Spectroscopy of Lambda-Hypernuclei by (e, e' K{sup +}) reaction and gamma-ray measurement (open access)

High Precision Spectroscopy of Lambda-Hypernuclei by (e, e' K{sup +}) reaction and gamma-ray measurement

Hypernuclei, with one nucleon converted into a hyperon and coupled back to the residual nuclear core, provide a new probe to study the hyperon-nucleon interaction and an additional strangeness degree of freedom to test the limit of our conventional nuclear models in solving the many body system. The First Lambda electroproduction experiment E89009(HNSS) at JLAB focusing on the Lambda hypernuclear spectroscopy in p-shell achieved the best resolution( FWHM: 500-600 keV) ever reached in this field. The unnatural parity (spin-flip) states were observed for the first time on the 12 / Lambda B missing mass spectrum. The detailed hypernuclear structure of 9 / Lambda Be produced through (k{sup -}, pi{sup -}) reaction in BNL-AGS, was studied with the hypernuclear gamma-ray spectroscopy by using a large acceptance germanium detector (Hyperball) in experiment E-930.
Date: August 1, 2001
Creator: Zhu, Xiaofeng
System: The UNT Digital Library
High-Tc SQUIDs: Noise and applications (open access)

High-Tc SQUIDs: Noise and applications

None
Date: August 1, 2001
Creator: Cho, Hsiao-Mei
System: The UNT Digital Library
High-Throughput Analysis With 96-Capillary Array Electrophoresis and Integrated Sample Preparation for DNA Sequencing Based on Laser Induced Fluorescence Detection (open access)

High-Throughput Analysis With 96-Capillary Array Electrophoresis and Integrated Sample Preparation for DNA Sequencing Based on Laser Induced Fluorescence Detection

The purpose of this research was to improve the fluorescence detection for the multiplexed capillary array electrophoresis, extend its use beyond the genomic analysis, and to develop an integrated micro-sample preparation system for high-throughput DNA sequencing. The authors first demonstrated multiplexed capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) separations in a 96-capillary array system with laser-induced fluorescence detection. Migration times of four kinds of fluoresceins and six polyaromatic hydrocarbons (PAHs) are normalized to one of the capillaries using two internal standards. The relative standard deviations (RSD) after normalization are 0.6-1.4% for the fluoresceins and 0.1-1.5% for the PAHs. Quantitative calibration of the separations based on peak areas is also performed, again with substantial improvement over the raw data. This opens up the possibility of performing massively parallel separations for high-throughput chemical analysis for process monitoring, combinatorial synthesis, and clinical diagnosis. The authors further improved the fluorescence detection by step laser scanning. A computer-controlled galvanometer scanner is adapted for scanning a focused laser beam across a 96-capillary array for laser-induced fluorescence detection. The signal at a single photomultiplier tube is temporally sorted to distinguish among the capillaries. The limit of detection for fluorescein is 3 x 10{sup -11} M …
Date: December 31, 2001
Creator: Xue, Gang
System: The UNT Digital Library
Inertial Confinement Fusion Annual Report 1999 (open access)

Inertial Confinement Fusion Annual Report 1999

The ICF Program has undergone a significant change in 1999 with the decommissioning of the Nova laser and the transfer of much of the experimental program to the OMEGA laser at the University of Rochester. The Nova laser ended operations with the final experiment conducted on May 27, 1999. This marked the end to one of DOE's most successful experimental facilities. Since its commissioning in 1985, Nova performed 13,424 experiments supporting ICF, Defense Sciences, high-power laser research, and basic science research. At the time of its commissioning, Nova was the world's most powerful laser. Its early experiments demonstrated that 3{omega} light could produce high-drive, low-preheat environment required for indirect-drive ICE. In the early 1990s, the technical program on Nova for indirect drive ignition was defined by the Nova technical contract established by National Academy Review of ICF in 1990. Successful completion of this research program contributed significantly to the recommendation by the ICF Advisory Committee in 1995 to proceed with the construction of the National Ignition Facility? Nova experiments also demonstrated the utility of high-powered lasers for studying the physics of interest to Defense Sciences. Now, high-powered lasers along with pulsed-power machines are the principal facilities for studying high energy …
Date: July 1, 2001
Creator: Kauffman, R.
System: The UNT Digital Library
The Influence of Ergonomics Training on Employee Behavior at Los Alamos National Laboratory (open access)

The Influence of Ergonomics Training on Employee Behavior at Los Alamos National Laboratory

A survey of employee behavior was conducted at Los Alamos National Laboratory (LANL). The objective of this study was to evaluate the prevalence of ergonomic behavior that decreased the chance of having a work-related musculoskeletal disorder (WMSD) among employees. The null hypothesis was tested to determine if there was a significant difference in ergonomic behavior between trained and untrained employees. The LANL employees were stratified by job series and then randomly selected to participate. The data were gathered using an electronic self-administered behavior questionnaire. The study population was composed of 6931 employees, and the response rate was 48%. The null hypothesis was rejected for twelve out of fifteen questions on the questionnaire. Logistic regression results indicate that the trained participants were more likely to report the risk-avoiding behavior, which supported the rejection of the null hypothesis for 60% of the questions. There was a higher frequency that the beneficial or risk-avoiding behavior was reported by the uninjured participants. Job series analysis revealed that ergonomics is an important issue among participants from all the job series. It also identified the occupational specialist classification (an administrative job), as the job series with the most occurrences of undesired ergonomic behaviors. In conclusion, there …
Date: January 1, 2001
Creator: Puckett, Leslie Guthrie
System: The UNT Digital Library