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Analysis of Multipactor Discharge

Description: Several comprehensive studies of radio frequency (rf) breakdown and rf heating are reported. They are of general interest to magnetic confinement fusion, rf linac, and high power microwave source development. The major results include: (1) a ground-breaking theory of multipactor discharge on dielectric, including a successful proof-of-principle experiment that verified the newly developed scaling laws, (2) an in depth investigation of the failure mechanisms of diamond windows and ceramic windows, and of the roles of graphitization, thin films of coating and contaminants, and (3) a most comprehensive theory, to date, on the heating of particulates by an electromagnetic pulse, and on the roles of rf magnetic field heating and of rf electric field heating, including the construction of new scaling laws that govern them. The above form a valuable knowledge base for the general problem of heating phenomenology.
Date: August 31, 2005
Creator: Lau, Y. Y.
Partner: UNT Libraries Government Documents Department

Mixture Preparation and Nitric Oxide Formation in a GDI Engine studied by Combined Laser Diagnostics and Numerical Modeling

Description: Through the combination of advanced imaging laser diagnostics with multi-dimensional computer models, a new understanding of the performance of direct-injection gasoline engines is pursuit. The work focuses on the fuel injection process, the breakup of the liquid into a fine spray and the mixing of the fuel with the in-cylinder gases. Non-intrusive laser diagnostics will be used to measure the spatial distribution of droplets and vaporized fuel with very high temporal resolution. These data along with temperature measurements will be used to validate a new spray breakup model for gasoline direct-injection. Experimental data on near wall fuel distributions will be used for comparison with a model that predicts the spray-wall interaction and the dynamics of the liquid film on the surface. Quantitative measurements of local nitric oxide concentrations inside the combustion chamber will provide a critical test for a numerical simulation of the nitric oxide formation process. This model is based on a modified flamelet approach and will be used to study the effects of exhaust gas recirculation.
Date: November 27, 2002
Creator: Sick, Volker & Assanis, Dennis N.
Partner: UNT Libraries Government Documents Department

Hydrogen Storage at Ambient Temperature by the Spillover Mechanism

Description: The goal of this project was to develop new nanostructured sorbent materials, using the hydrogen spillover mechanism that could meet the DOE 2010 system targets for on-board vehicle hydrogen storage. Hydrogen spillover may be broadly defined as the transport (i.e., via surface diffusion) of dissociated hydrogen adsorbed or formed on a first surface onto another surface. The first surface is typically a metal (that dissociates H2) and the second surface is typically the support on which the metal is doped. Hydrogen spillover is a well documented phenomenon in the catalysis literature, and has been known in the catalysis community for over four decades, although it is still not well understood.1, 2 Much evidence has been shown in the literature on its roles played in catalytic reactions. Very little has been studied on hydrogen storage by spillover at ambient temperature. However, it is also known to occur at such temperature, e.g., direct evidence has been shown for spillover on commercial fuel-cell, highly dispersed Pt/C, Ru/C and PtRu/C catalysts by inelastic neutron scattering.3 To exploit spillover for storage, among the key questions are whether spillover is reversible at ambient temperature and if the adsorption (refill) and desorption rates at ambient temperature are fast enough for automotive applications. In this project, we explored new sorbents by using a transition metal (e.g., Pt, Ru, Pd and Ni) as the H2 dissociation source and sorbents as the hydrogen receptor. The receptors included superactivated carbons (AX-21 and Maxsorb), metal organic frameworks (MOFs) and zeolites. Different metal doping methods have been used successfully to achieve high metal dispersion thereby allowing significant spillover enhancements, as well as a bridging technique used for bridging to MOFs. Among the metals tested, Pt is the hardest to achieve high metal dispersion (and consequently spillover) while Ru is the easiest to disperse. ...
Date: February 4, 2011
Creator: Yang , Ralph T.
Partner: UNT Libraries Government Documents Department

Simplification of Methods for PET Radiopharmaceutical Syntheses

Description: In an attempt to develop simplified methods for radiochemical synthesis of radiopharmaceuticals useful in Positron Emission Tomography (PET), current commercially available automated synthesis apparati were evaluated for use with solid phase synthesis, thin-film techniques, microwave-accelerated chemistry, and click chemistry approaches. Using combinations of these techniques, it was shown that these automated synthesis systems can be simply and effectively used to support the synthesis of a wide variety of carbon-11 and fluorine-18 labeled compounds, representing all of the major types of compounds synthesized and using all of the common radiochemical precursors available. These techniques are available for use to deliver clinically useful amounts of PET radiopharmaceuticals with chemical and radiochemical purities and high specific activities, suitable for human administration.
Date: December 27, 2011
Creator: Kilbourn, Michael, R.
Partner: UNT Libraries Government Documents Department

Precision Photometry to Study the Nature of Dark Energy

Description: Over the past decade scientists have collected convincing evidence that the expansion of the universe is accelerating, leading to the conclusion that the content of our universe is dominated by a mysterious 'dark energy'. The fact that present theory cannot account for the dark energy has made the determination of the nature of dark energy central to the field of high energy physics. It is expected that nothing short of a revolution in our understanding of the fundamental laws of physics is required to fully understand the accelerating universe. Discovering the nature of dark energy is a very difficult task, and requires experiments that employ a combination of different observational techniques, such as type-Ia supernovae, gravitational weak lensing surveys, galaxy and galaxy cluster surveys, and baryon acoustic oscillations. A critical component of any approach to understanding the nature of dark energy is precision photometry. This report addresses just that. Most dark energy missions will require photometric calibration over a wide range of intensities using standardized stars and internal reference sources. All of the techniques proposed for these missions rely on a complete understanding of the linearity of the detectors. The technical report focuses on the investigation and characterization of 'reciprocity failure', a newly discovered count-rate dependent nonlinearity in the NICMOS cameras on the Hubble Space Telescope. In order to quantify reciprocity failure for modern astronomical detectors, we built a dedicated reciprocity test setup that produced a known amount of light on a detector, and to measured its response as a function of light intensity and wavelength.
Date: January 30, 2011
Creator: Lorenzon, Wolfgang & Schubnell, Michael
Partner: UNT Libraries Government Documents Department

Final Technical Report for University of Michigan Industrial Assessment Center

Description: The UM Industrial Assessment Center assisted 119 primary metals, automotive parts, metal casting, chemicals, forest products, agricultural, and glass manufacturers in Michigan, Ohio and Indiana to become more productive and profitable by identifying and recommending specific measures to improve energy efficiency, reduce waste and increase productivity. This directly benefits the environment by saving a total of 309,194 MMBtu of energy resulting in reduction of 0.004 metric tons of carbon emissions. The $4,618,740 implemented cost savings generated also saves jobs that are evaporating from the manufacturing industries in the US. Most importantly, the UM Industrial Assessment Center provided extremely valuable energy education to forty one UM graduate and undergraduate students. The practical experience complements their classroom education. This also has a large multiplier effect because the students take the knowledge and training with them.
Date: April 17, 2007
Creator: Atreya, Arvind
Partner: UNT Libraries Government Documents Department

Ultrafast X-Ray Coherent Control

Description: This main purpose of this grant was to develop the nascent #12;eld of ultrafast x-ray science using accelerator-based sources, and originally developed from an idea that a laser could modulate the di#11;racting properties of a x-ray di#11;racting crystal on a fast enough time scale to switch out in time a shorter slice from the already short x-ray pulses from a synchrotron. The research was carried out primarily at the Advanced Photon Source (APS) sector 7 at Argonne National Laboratory and the Sub-Picosecond Pulse Source (SPPS) at SLAC; in anticipation of the Linac Coherent Light Source (LCLS) x-ray free electron laser that became operational in 2009 at SLAC (all National User Facilities operated by BES). The research centered on the generation, control and measurement of atomic-scale dynamics in atomic, molecular optical and condensed matter systems with temporal and spatial resolution . It helped develop the ultrafast physics, techniques and scienti#12;c case for using the unprecedented characteristics of the LCLS. The project has been very successful with results have been disseminated widely and in top journals, have been well cited in the #12;eld, and have laid the foundation for many experiments being performed on the LCLS, the world's #12;rst hard x-ray free electron laser.
Date: May 1, 2009
Creator: Reis, David
Partner: UNT Libraries Government Documents Department

Cloud/Aerosol Parameterizations: Application and Improvement of General Circulation Models

Description: One of the biggest uncertainties associated with climate models and climate forcing is the treatment of aerosols and their effects on clouds. The effect of aerosols on clouds can be divided into two components: The first indirect effect is the forcing associated with increases in droplet concentrations; the second indirect effect is the forcing associated with changes in liquid water path, cloud morphology, and cloud lifetime. Both are highly uncertain. This project applied a cloud-resolving model to understand the response of clouds under a variety of conditions to changes in aerosols. These responses are categorized according to the large-scale meteorological conditions that lead to the response. Meteorological conditions were sampled from various fields, which, together with a global aerosol model determination of the change in aerosols from present day to pre-industrial conditions, was used to determine a first order estimate of the response of global cloud fields to changes in aerosols. The response of the clouds in the NCAR CAM3 GCM coupled to our global aerosol model were tested by examining whether the response is similar to that of the cloud resolving model and methods for improving the representation of clouds and cloud/aerosol interactions were examined.
Date: June 30, 2012
Creator: Penner, Joyce
Partner: UNT Libraries Government Documents Department

Particle physics: CP violation in hyperon decays

Description: The primary research activities under this grant were in E871 (HyperCP) at Fermilab, a search for CP violation in hyperon decays which completed data taking in January, 2000. HyperCP is an experiment designed to perform a sensitive search for direct CP violation in the decays of cascade ({Xi}) and {Lambda} hyperons by looking for an asymmetry between particle and antiparticle decay parameters. The experiment is expected to achieve a sensitivity {approx}10{sup -4} in the decay parameters. Standard model predictions for this CP-violating asymmetry range from 0.3 to 5 x 10{sup -4}. A difference between the decay parameters for particle and antiparticle is direct evidence that CP symmetry is violated. A non-zero asymmetry would be the first evidence for CP violation outside of the K{sup o} system. Recent results from KTeV indicate a direct CP violation in K{sup o} decays, which suggests that CP violation will appear in other decays. In addition, we will look at a number of rare hyperon decays involving muons. These probe important new physics topics such as Majorana neutrinos and lepton number violating processes. The latter are of great current interest because new evidence for neutrino oscillations indicate lepton flavor violation does occur. Our data will lead to an improvement in the limits on branching ratios for these processes typically by three to four orders-of-magnitude. The muon detector construction and data resulting from it have been the responsibility of the Michigan group. We are now leading the analysis of the rare muon-related decay modes, and were responsible for the muon system and beam monitor upgrades for the 1999 run.
Date: October 31, 2000
Creator: Longo, Michael J.
Partner: UNT Libraries Government Documents Department

A Novel Approach to Materials Development for Advanced Reactor Systems - Quarterly Progress Report: Year 2; Quarter 1

Description: OAK B188 A Novel Approach to Materials Development for Advanced Reactor Systems - Quarterly Progress Report: Year 2; Quarter 1. There are three major goals for year two of the program. First, to build on the successful initial experiments on proton irradiation of pressure vessel steel to expand the irradiations to study dose rate and temperature effects, radiation effects on commercial alloys and to better characterize the precipitates. Second, we will begin irradiation and characterization of the Zircaloy alloys. Finally, we will continue low temperature irradiations and begin irradiation of chromium pre-enriched samples and cold-worked samples to assess the role of microstructure in IASCC of austenitic stainless steels. In quarter 1 of year 2, the project goal was to complete irradiation of model alloys of RPV steels for a range of doses and an initial sample characterization. We also planned to begin characterization of Zircalloy alloy samples and to make a set of cold-worked samples of 304 SS that would have a fixed hardness following subsequent irradiation to different doses.
Date: June 25, 2002
Creator: Was, G. S.; Atzmon, M. & Wang, L.
Partner: UNT Libraries Government Documents Department

The Migration and Entrapment of DNAPLs in Physically and Chemically Heterogeneous Porous Media - Final Report - 09/15/1996 - 09/15/2000

Description: Hazardous dense nonaqueous phase liquids (DNAPLs), such as chlorinated solvents, are slightly water soluble and pose a serious threat to soil and groundwater supplies in many portions of the United States. The migration and entrapment of DNAPLs in the subsurface environment is typically believed to be controlled by physical heterogeneities; i.e, layers and lenses of contrasting soil texture. The rationale for this assumption is that capillarity, as determined by the soil texture, is the dominant transport mechanism. Capillarity also depends on interfacial tension and medium wettability. Interfacial tension and medium wettability may be spatially and temporally dependent due to variations in aqueous phase chemistry, contaminant aging, and/or variations in mineralogy and organic matter distributions. Such chemical heterogeneities have largely been ignored to date, even though they are known to have dramatic effects on the hydraulic property relations. Numerical multiphase flow and transport models typically assume that solids are water-wet and that interfacial tension is constant. The primary objective of this research is to investigate the influence of coupled physical and chemical heterogeneities on the migration and entrapment of DNAPLs. This objective will be accomplished through a combination of laboratory and numerical experiments. Laboratory experiments will be conducted to examine: (i) aqueous phase chemistry effects on medium wettability and interfacial tension; and (ii) relative permeability-saturation-capillary pressure relations for chemically heterogeneous systems. An important objective of this research is to modify a two-dimensional multiphase flow and transport model to account for chemically and physically heterogeneous systems. This numerical simulator will be used in conjunction with independently measured parameters to simulate two-dimensional DNAPL infiltration experiments. Comparisons of simulated and laboratory data will provide a means to experimentally validate this model. The validated numerical simulator will subsequently be employed to investigate various innovative remediation schemes such as the use of surfactants and in situ ...
Date: September 15, 2000
Creator: Abriola, L. M. & Demond, A. H.
Partner: UNT Libraries Government Documents Department

Radiation Effects on Sorption and Mobilization of Radionuclides during Transport through Geosphere

Description: Site restoration activities at DOE facilities and the permanent disposal of nuclear waste generated at DOE facilities involve working with and within various types and levels of radiation fields. Radionuclide decay and the associated radiation fields lead to physical and chemical changes that can degrade or enhance material properties. The principal sources of radiation at the DOE sites are the actinides and fission-products contained in high-level wastes currently in storage. Alpha-decay of the actinide elements and beta-decay of the fission products lead to atomic scale changes in the material (radiation damage and transmutation). During site restoration, materials will be exposed to radiation fields that exceed 104 rad/hr. The radiation exposure due to the release and sorption of long-lived actinides (e.g., 237Np) and fission products (e.g., 137Cs and 90Sr) may cause changes in important properties (e.g., cation exchange capacity) in geological materials (e.g., clays and zeolites) along transport pathways. Among these materials, clays and zeolites, which are expected to sorb and immobilize radionuclides, are known to be extremely susceptible to radiation-induced structure changes (e.g., bubble formation and solid state amorphization) through both collisional displacement and ionization processes. These changes will inevitably affect (either negatively or positively) the further sorption and the migration of radionuclides at waste sites (e.g., vadose zone at Hanford). Current models used for the longterm prediction of radionuclide transport have proven to be inadequate and unrealistic; however, these previous models did not take radiation effects into consideration.
Date: March 14, 2002
Creator: Wang, L.M.; Ewing, R.C. & Hayes, K.F.
Partner: UNT Libraries Government Documents Department

Engineered Natural Geosorbents for In-Situ Immobilization of DNAPLs and Heavy Metals

Description: The report summarizes work progress from 9/15/02-12/31/2003 for the project. Progresses in these five specific areas of investigation are summarized: (1) Production of engineered natural geosorbents (ENGs); (2) Characterization of the physicochemical properties of ENGs; (3) Characterization of the sorption and desorption properties of ENGs for TCE, PCE; (4) Characterization of the sorption and desorption properties of ENGs for heavy metals 4a; and (5) Characterization of the competitive sorption and desorption properties of ENGs for DNAPL and heavy metals.
Date: June 1, 2003
Creator: Weber, Walter J.
Partner: UNT Libraries Government Documents Department

Annual Scientific Report 2004-2005 Proton Radiography: Cross Section Measurements and Detector Development

Description: Our research grant provides support for a program to measure forward production of neutrons and photons produced by high-energy proton beams striking a variety of targets. This will provide data essential to proton radiography. This work is carried out in conjunction with the Fermilab E-907 (MIPP) collaboration including physicists from Lawrence Livermore Laboratory. Our group is responsible for the E907 forward neutron/photon calorimeters. We are taking a leading role in obtaining and analyzing the forward production data and in helping to develop an optimal detector for proton radiography. With the support of our Stewardship Science Academic Alliances Grant DE-FG03-03NA00077, we were able to design, build, and commission the calorimeters on budget and ahead of schedule. E-907 officially started physics running at Fermilab in January 2005. We expect to continue data taking through October 2005. The analysis of the data, which we expect will be challenging because data from many different detector systems must be understood and merged, will take several years. Our group is in a unique position to complete the measurements, analyze the data, and help set up a database to be used by LLNL and LANL to make this information accessible for proton radiography. This work will be done in conjunction with the Livermore Laboratory High Energy Physics and Computational Nuclear Physics Groups. The project is meeting or exceeding its technical milestones, while remaining within its budget.
Date: March 11, 2005
Creator: Longo, Michael J.
Partner: UNT Libraries Government Documents Department

Radiation Effects on Materials in the Near-Field of a Nuclear Waste Repository

Description: Site restoration activities at US DOE facilities and the permanent disposal of nuclear waste generated at DOE facilities require working with and within various types and levels of radiation fields. Once the nuclear waste is incorporated into a final form, radioactive decay will decrease the radiation field over geologic time scales, but the alpha-decay dose for these solids will still reach values as high as 1018 alpha-decay events/gm in periods as short as 1,000 years. This dose is well within the range for which important chemical (e.g., increased leach rate) and physical (e.g., volume expansion) changes may occur in crystalline ceramics. Release and sorption of long-lived actinides can also provide a radiation exposure to backfill materials, and changes in important retardation properties (e.g., cation exchange capacity) may occur. The objective of this research program has been to evaluate the long-term radiation effects in materials used in processing high-level nuclear waste or materials in the near-field of a nuclear waste repository.
Date: June 1, 2000
Creator: Wang, Lu-Min & Ewing, Rodney C.
Partner: UNT Libraries Government Documents Department

Engineered Natural Geosorbents for In Situ Immobilization of DNAPLs and Heavy Metals

Description: The overarching goal of the proposed research is to develop a comprehensive data and mechanistic knowledge base with respect to the binding and sequestration reactions of organic DNAPL components and heavy metals with different types of soil matrices. A principal ultimate use of this knowledge and information base will be its application as a platform for designing specifically engineered natural geosorbents (ENGs) capable of in situ long-term immobilization of non-aqueous phase organic liquids and heavy metals at contaminated DOE sites and facilities. The sorption and sequestration performance of ENGs for DNAPLs and heavy metals will be monitored and evaluated by measuring their environmental mobility (desorption and leaching) and bioavailability (toxicity and bioaccumulation) to indicator organisms. Appropriate field tests will be designed to demonstrate the efficacy of in-situ immobilization and inactivation of DNAPLs and heavy metals using the engineered natural geosorbents .
Date: June 1, 2003
Creator: Weber, Walter J. Jr., & Tang, Jixin
Partner: UNT Libraries Government Documents Department

FINAL SCIENTIFIC REPORT - PROTON RADIOGRAPHY: CROSS SECTION MEASUREMENTS AND DETECTOR DEVELOPMENT

Description: Proton radiography offers significant advantages over conventional X-ray radiography, including the capability of looking into thick, dense materials, better contrast for a wide range of materials, sensitivity to different materials of similar density, and better resolution because of the ability to focus beams. In order to achieve this capability it is crucial to understand the background due to neutrons and photons and to develop techniques to reduce it to tolerable levels. The physics goal of this project is to measure forward production of neutrons and photons produced by high-energy proton beams striking a variety of targets. This work is being carried out in conjunction with the Fermilab Experiment 907 (MIPP) collaboration including physicists from Lawrence Livermore Laboratory. Our group is responsible for the E907 forward neu-tron/photon calorimeters. These are the only detectors in the experiment that provide informa-tion on neutrons and photons. We are taking a leading role in obtaining and analyzing the for-ward production data and in developing an optimal detector for proton radiography. With the support of our Stewardship Science Academic Alliances grant, we were able to design, build, and commission the calorimeters on budget and ahead of schedule. E-907 officially started physics running at Fermilab in January 2005, and data taking continued through February 2006. Data were taken on a range of targets, from liquid hydrogen to uranium, at beam energies from 5 GeV/c to 120 GeV/c. The analysis of the data is challenging because data from many different detector systems must be understood and merged and over 31 million events were accumulated. Our recent efforts have been devoted to the calibration of the neutron and photon detectors, to track and shower reconstruction, identification of forward-going neutrons, and simulation of the calorimeters in a Monte Carlo. Reconstruction of the data with improved tracking is underway.
Date: May 11, 2007
Creator: Longo, Michael J.; Gustafson, H. Richard.; Rajaram, Durga & Nigmanov, Turgun
Partner: UNT Libraries Government Documents Department