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Beam Tools for Geant4 (User's Guide)

Description: Geant4 is a tool kit developed by a collaboration of physicists and computer professionals in the high energy physics field for simulation of the passage of particles through matter. The motivation for the development of the Beam Tools is to extend the Geant4 applications to accelerator physics. The Beam Tools are a set of C++ classes designed to facilitate the simulation of accelerator elements: r.f. cavities, magnets, absorbers, etc. These elements are constructed from Geant4 solid volumes like boxes, tubes, trapezoids, or spheers. There are many computer programs for beam physics simulations, but Geant4 is ideal to model a beam through a material or to integrate a beam line with a complex detector. There are many such examples in the current international High Energy Physics programs. For instance, an essential part of the R&D associated with the Neutrino Source/Muon Collider accelerator is the ionization cooling channel, which is a section of the system aimed to reduce the size of the muon beam in phase space. The ionization cooling technique uses a combination of linacs and light absorbers to reduce the transverse momentum and size of the beam, while keeping the longitudinal momentum constant. The MuCool/MICE (muon cooling) experiments need accurate simulations of the beam transport through the cooling channel in addition to a detailed simulation of the detectors designed to measure the size of the beam. The accuracy of the models for physics processes associated with muon ionization and multiple scattering is critical in this type of applications. Another example is the simulation of the interaction region in future accelerators. The high luminosity and background environments expected in the Next Linear Collider (NLC) and the Very Large Hadron Collider (VLHC) pose great demand on the detectors, which may be optimized by means of a simulation of the detector-accelerator interface.
Date: December 2, 2002
Creator: V.Daniel Elvira, Paul Lebrun and Panagiotis Spentzouris
Partner: UNT Libraries Government Documents Department

Final report for Grant No. DOE/DE-FG02-98ER14909: Experimental and modeling studies of nanometer aerosol filtration

Description: The primary objective is to perform a fundamental study of filtration of nanoparticles, and to obtain filtration knowledge necessary to design particle collection devices/systems for nanoparticle processing and for preventing nanoparticle emissions into the environment. The research covered a wide area relevant to nanoparticle filtration, under these main topics: (1) nanoparticle filtration and molecular dynamics simulation, (2) nanoparticle virtual impactor, (3) particle transport under low pressure, and (4) development of a high-throughput nanoparticle generator. A number of novel tools and numerical models have been developed under the DOE support.
Date: December 10, 2002
Creator: Pui, David Y. H. & Chen, Da-Ren
Partner: UNT Libraries Government Documents Department

STREAM II-V4: Revision for STREAM II-V3 to Allow Mouse-Driven Selection of Release Location from a Graphical User Interface

Description: STREAM II-V3 is an aqueous transport module of the Savannah River Site emergency response Weather INformation Display (WIND) system. Stream II-V3 predicts peak concentration and peak concentration arrival time at downstream locations for releases from the SRS facilities to the Savannah River. Fifteen pre-determined potential release locations from SRS facilities were built into the current STREAM II-V3 model. Therefore, STREAM II-V3 can not be used for situations in which release locations differ from the fifteen pre-determined locations. To eliminate this limitation, STREAM II-V3 was upgraded. The revised STREAM II-V4 allows users to select the release location anywhere along the specified SRS main streams or the Savannah River by mouse clicking on a map displayed on the computer monitor.
Date: December 18, 2002
Creator: Chen, K.F.
Partner: UNT Libraries Government Documents Department

Reductive immobilization of U(VI) in Fe(III) oxide-reducing subsurface sediments: Analysis of coupled microbial-geochemical processes in experimental reactive transport systems

Description: Although the fundamental microbiological and geochemical processes underlying the potential use of dissimilatory metal-reducing bacteria (DMRB) to create subsurface redox barriers for immobilization of uranium and other redox-sensitive metal/radionuclide contaminants are well-understood (Lovley et al., 1991; Gorby and Lovley, 1992; Lovley and Phillips, 1992; Lovley, 1995; Fredrickson et al., 2000; Wielinga et al., 2000; Wielinga et al., 2001), several fundamental scientific questions need to be addressed in order to understand and predict how such treatment procedures would function under in situ conditions in the subsurface. These questions revolve around the dynamic interactions between hydrologic flux and the coupled microbial-geochemical processes which are likely to occur within a redox barrier treatment zone.
Date: December 6, 2002
Creator: Roden, Eric E.; Urrutia, Matilde M.; Barnett, Mark O. & Lange, Clifford r.
Partner: UNT Libraries Government Documents Department

Electroabsorption and Transport Measurements and Modeling Research in Amorphous Silicon Based Solar Cells: Final Technical Report, 24 March 1998--15 August 2002

Description: The contributions of this research project to amorphous silicon solar cells are in the following areas: (1) Improved understanding of the open-circuit voltage; (2) Improved knowledge of the built-in potential; (3) Variations in hole drift-mobilities for differing forms of a-Si:H; (4) Infrared spectroscopy of interfaces in a-Si:H cells; (5) Polymer p-layers; and (6) Hydrogen-based models for defects and metastability.
Date: December 1, 2002
Creator: Schiff, E. A.; Middya, A. R.; Lyou, J.; Kopidakis, N.; Rane, S.; Rao, P. et al.
Partner: UNT Libraries Government Documents Department

Assessment of Reactivity Margins and Loading Curves for PWR Burnup Credit Cask Designs

Description: This report presents studies to assess reactivity margins and loading curves for pressurized water reactor (PWR) burnup-credit criticality safety evaluations. The studies are based on a generic high-density 32-assembly cask and systematically vary individual calculational (depletion and criticality) assumptions to demonstrate the impact on the predicted effective neutron multiplication factor, k{sub eff}, and burnup-credit loading curves. The purpose of this report is to provide a greater understanding of the importance of input parameter variations and quantify the impact of calculational assumptions on the outcome of a burnup-credit evaluation. This study should provide guidance to regulators and industry on the technical areas where improved information will most enhance the estimation of accurate subcritical margins. Based on these studies, areas where future work may provide the most benefit are identified. The report also includes an evaluation of the degree of burnup credit needed for high-density casks to transport the current spent nuclear fuel inventory. By comparing PWR discharge data to actinide-only based loading curves and determining the number of assemblies that meet the loading criteria, this evaluation finds that additional negative reactivity (through either increased credit for fuel burnup or cask design/utilization modifications) is necessary to accommodate the majority of current spent fuel assemblies in high-capacity casks. Assemblies that are not acceptable for loading in the prototypic high-capacity cask may be stored or transported by other means (e.g., lower capacity casks that utilize flux traps and/or increased fixed poison concentrations or high-capacity casks with design/utilization modifications).
Date: December 17, 2002
Creator: Wagner, J.C.
Partner: UNT Libraries Government Documents Department

Theory and Simulation of the Physics of Space Charge Dominated Beams

Description: This report describes modeling of intense electron and ion beams in the space charge dominated regime. Space charge collective modes play an important role in the transport of intense beams over long distances. These modes were first observed in particle-in-cell simulations. The work presented here is closely tied to the University of Maryland Electron Ring (UMER) experiment and has application to accelerators for heavy ion beam fusion.
Date: December 9, 2002
Creator: Haber, Irving
Partner: UNT Libraries Government Documents Department

Low-Temperature, Vacuum-Aided Thermal Desorption Studies on a Simulated Organic Sludge Waste

Description: This report describes an initial set of small scale lab tests conducted on surrogate waste materials to investigate mass release behavior of volatile organics (VOC’s) from a solidified liquid organic sludge matrix under vacuumaided, low-temperature thermal desorption conditions. Low temperature thermal desorption is being considered as a potential processing technology alternative to incineration, to remove gas generation limitations affecting the transportation of transuranic (TRU) contaminated organic sludge wastes to a designated off-site repository (i.e., the Waste Isolation Pilot Plant). The lab-scale tests provide initial exploratory level information on temperature profiles and rates of volatile organic desorption for a range of initial VOC/oil liquid mixture concentrations in a calcium silicate matrix, under low temperature heating and vacuum boundary conditions that are representative of potentially desirable “in-drum desorption” conditions. The results of these tests indicate that reduced operating pressures have a potential for significantly enhancing the rate of thermal desorption experienced from a liquid organic/oil solidified “sludge” waste. Furthermore, the results indicate that in-drum thermal desorption can be performed on organic sludge wastes, at reduced pressures, while maintaining an operating temperature sufficiently low to prevent destruction of the waste drum packaging materials (confinement) surrounding the waste. The results also indicate that VOC release behavior/rates in the vacuum thermal desorption process cannot be represented by a simple liquid-liquid mass-diffusion model, since overall mass release rates observed are generally two orders of magnitude greater than predicted by simple liquid-liquid mass diffusion. This is partially attributed to the effects of the transient temperature profiles within the sludge during heat up; however, the primary cause is thought to be micro boiling of the volatile organics within the simulated sludge. Micro boiling of VOC’s would be expected to occur in localized volumes within the organic sludge where temperatures exceed the volatile organic saturation temperature sufficiently to form ...
Date: December 1, 2002
Creator: Farnsworth, R. K.; Peterman, D. R.; Anderson, Gary L. & Garn, T. G.
Partner: UNT Libraries Government Documents Department

Deep-Burn Modular Helium Reactor Fuel Development Plan

Description: This document contains the workscope, schedule and cost for the technology development tasks needed to satisfy the fuel and fission product transport Design Data Needs (DDNs) for the Gas Turbine-Modular Helium Reactor (GT-MHR), operating in its role of transmuting transuranic (TRU) nuclides in spent fuel discharged from commercial light-water reactors (LWRs). In its application for transmutation, the GT-MHR is referred to as the Deep-Burn MHR (DB-MHR). This Fuel Development Plan (FDP) describes part of the overall program being undertaken by the U.S. Department of Energy (DOE), utilities, and industry to evaluate the use of the GT-MHR to transmute transuranic nuclides from spent nuclear fuel. The Fuel Development Plan (FDP) includes the work on fuel necessary to support the design and licensing of the DB-MHR. The FDP is organized into ten sections. Section 1 provides a summary of the most important features of the plan, including cost and schedule information. Section 2 describes the DB-MHR concept, the features of its fuel and the plan to develop coated particle fuel for transmutation. Section 3 describes the knowledge base for fabrication of coated particles, the experience with irradiation performance of coated particle fuels, the database for fission product transport in HTGR cores, and describes test data and calculations for the performance of coated particle fuel while in a repository. Section 4 presents the fuel performance requirements in terms of as-manufactured quality and performance of the fuel coatings under irradiation and accident conditions. These requirements are provisional because the design of the DB-MHR is in an early stage. However, the requirements are presented in this preliminary form to guide the initial work on the fuel development. Section 4 also presents limits on the irradiation conditions to which the coated particle fuel can be subjected for the core design. These limits are based on past ...
Date: December 2, 2002
Creator: McEachern, D
Partner: UNT Libraries Government Documents Department

Comparison of Implicit and Symbolic Implicit Monte Carlo Line Transport with Frequency Weight Vector Extension

Description: We compare the Implicit Monte Carlo (IMC) technique to the Symbolic IMC (SIMC) technique, with and without weight vectors in frequency space, for time-dependent line transport in the presence of collisional pumping. We examine the efficiency and accuracy of the IMC and SIMC methods for test problems involving the evolution of a collisionally pumped trapping problem to its steady-state, the surface heating of a cold medium by a beam, and the diffusion of energy from a localized region that is collisionally pumped. The importance of spatial biasing and teleportation for problems involving high opacity is demonstrated. Our numerical solution, along with its associated teleportation error, is checked against theoretical calculations for the last example.
Date: December 3, 2002
Creator: McKinley, M S; Brooks III, E D & Szoke, A
Partner: UNT Libraries Government Documents Department

Estimating Field-Scale Hydraulic Parameters of Heterogeneous Soils Using A Combination of Parameter Scaling and Inverse Methods

Description: As the Hanford Site transitions into remediation of contaminated soil waste sites and tank farm closure, more information is needed about the transport of contaminants as they move through the vadose zone to the underlying water table. The hydraulic properties must be characterized for accurate simulation of flow and transport. This characterization includes the determination of soil texture types, their three-dimensional distribution, and the parameterization of each soil texture. This document describes a method to estimate the soil hydraulic parameter using the parameter scaling concept (Zhang et al. 2002) and inverse techniques. To this end, the Groundwater Protection Program Science and Technology Project funded vadose zone transport field studies, including analysis of the results to estimate field-scale hydraulic parameters for modeling. Parameter scaling is a new method to scale hydraulic parameters. The method relates the hydraulic-parameter values measured at different spatial scales for different soil textures. Parameter scaling factors relevant to a reference texture are determined using these local-scale parameter values, e.g., those measured in the lab using small soil cores. After parameter scaling is applied, the total number of unknown variables in hydraulic parameters is reduced by a factor equal to the number of soil textures. The field-scale values of the unknown variables can then be estimated using inverse techniques and a well-designed field experiment. Finally, parameters for individual textures are obtained through inverse scaling of the reference values using an a priori relationship between reference parameter values and the specific values for each texture. Inverse methods have the benefits of 1) calculating parameter values that produce the best-fit between observed and simulated values, 2) quantifying the confidence limits in parameter estimates and the predictions, 3) providing diagnostic statistics that quantify the quality of calibration and data shortcomings and needs, and 4) not restricting the initial and boundary-flow conditions, ...
Date: December 10, 2002
Creator: Zhang, Z. F.; Ward, Andy L. & Gee, Glendon W.
Partner: UNT Libraries Government Documents Department

Photocharge Transport and Recombination Measurements in Amorphous Silicon Films and Solar Cells by Photoconductive Frequency Mixing: Final Subcontract Report, 20 April 1998-30 June 2002

Description: The tasks carried out under this subcontract focused on characterizing the charge transport, opto-electronic, and structural properties of a number of amorphous and microcrystalline semiconductors prepared by several techniques. The dominant approach to accomplish the tasks of the present phase of the program is the photoconductive frequency mixing technique. This technique enabled us to determine separately the drift mobility and the photomixing lifetime of the photogenerated carriers. The technique is based on the idea of heterodyne detection for photoconductors. When two similarly polarized monochromatic optical beams of slightly different frequencies are incident on a photoconductor, the photocurrent produced, when a dc bias is applied, will contain components resulting from the square of the sum of the incident electric fields. Consequently, a photocurrent composed of a dc and a microwave current due to the beat frequency of the incident fields will be produced; these two currents allow a separate determination of the drift mobility and the photomixing lifetime. In the present work, we improved the instrumentation of the photomixing measurements by applying bias pulses of arbitrary width and frequency. The longitudinal modes of a He-Ne laser were used to generate a beat frequency of 252 MHz; all the measurements were performed at this frequency for the data indicated in the accompanying figures and tables. Results from this technique, as well as FTIR, XRD, SAXS, and optical spectroscopy, are presented in the full report.
Date: December 1, 2002
Creator: Braunstein, R.; Boshta, M.; Sheng, S.; Kattwinkel, A.; Liebe, J. & Sun, G.
Partner: UNT Libraries Government Documents Department

Power Systems Development Facility Gasification Test Run TC10

Description: This report discusses Test Campaign TC10 of the Kellogg Brown & Root, Inc. (KBR) Transport Gasifier train with a Siemens Westinghouse Power Corporation (Siemens Westinghouse) particle filter system at the Power Systems Development Facility (PSDF) located in Wilsonville, Alabama. The Transport Gasifier is an advanced circulating fluidized-bed gasifier designed to operate as either a combustor or a gasifier in air- or oxygen-blown mode of operation using a particulate control device (PCD). The Transport Gasifier was operated as a pressurized gasifier during TC10 in air- (mainly for transitions and problematic operations) and oxygen-blown mode. Test Run TC10 was started on November 16, 2002, and completed on December 18, 2002. During oxygen-blown operations, gasifier temperatures varied between 1,675 and 1,825 F at pressures from 150 to 180 psig. After initial adjustments were made to reduce the feed rate, operations with the new fluidized coal feeder were stable with about half of the total coalfeed rate through the new feeder. However, the new fluidized-bed coal feeder proved to be difficult to control at low feed rates. Later the coal mills and original coal feeder experienced difficulties due to a high moisture content in the coal from heavy rains. Additional operational difficulties were experienced when several of the pressure sensing taps in the gasifier plugged. As the run progressed, modifications to the mills (to address processing the wet coal) resulted in a much larger feed size. This eventually resulted in the accumulation of large particles in the circulating solids causing operational instabilities in the standpipe and loop seal. Despite problems with the coal mills, coal feeder, pressure tap nozzles and the standpipe, the gasifier did experience short periods of stability during oxygenblown operations. During these periods, the syngas quality was high. During TC10, the gasifier gasified over 609 tons of Powder River Basin subbituminous ...
Date: December 30, 2002
Creator: Services, Southern Company
Partner: UNT Libraries Government Documents Department

Development of OTM Syngas Process and Testing of Syngas Derived Ultra-clean Fuels in Diesel Engines and Fuel Cells

Description: This topical report summarizes work accomplished for the Program from November 1, 2001 to December 31, 2002 in the following task areas: Task 1: Materials Development; Task 2: Composite Development; Task 4: Reactor Design and Process Optimization; Task 8: Fuels and Engine Testing; 8.1 International Diesel Engine Program; 8.2 Nuvera Fuel Cell Program; and Task 10: Program Management. Major progress has been made towards developing high temperature, high performance, robust, oxygen transport elements. In addition, a novel reactor design has been proposed that co-produces hydrogen, lowers cost and improves system operability. Fuel and engine testing is progressing well, but was delayed somewhat due to the hiatus in program funding in 2002. The Nuvera fuel cell portion of the program was completed on schedule and delivered promising results regarding low emission fuels for transportation fuel cells. The evaluation of ultra-clean diesel fuels continues in single cylinder (SCTE) and multiple cylinder (MCTE) test rigs at International Truck and Engine. FT diesel and a BP oxygenate showed significant emissions reductions in comparison to baseline petroleum diesel fuels. Overall through the end of 2002 the program remains under budget, but behind schedule in some areas.
Date: December 31, 2002
Creator: Robinson, E. T.; Meagher, James P.; Apte, Prasad; Gui, Xingun; Bulicz, Tytus R.; Aasland, Siv et al.
Partner: UNT Libraries Government Documents Department

Final report: FASEB Summer Research Conference on ''Post-transcriptional control of gene expression: Effectors of mRNA decay'' [agenda and attendees list]

Description: The goal of this meeting was to provide an interactive forum for scientists working on prokaryotic and eukaryotic mRNA decay. A special seminar presented by a leader in the field of mRNA decay in S. cerevisiae focused on what is known and what needs to be determined, not only for yeast but for other organisms. The large attendance (110 participants) reflects the awareness that mRNA decay is a key player in gene regulation in a way that is affected by the many steps that precede mRNA formation. Sessions were held on the following topics: mRNA transport and mRNP; multicomponent eukaryotic nucleases; nonsense-mediated mRNA decay and nonsense-associated altered splicing; Cis-acting sequences/Trans-acting factors of mRNA decay; translational accuracy; multicomponent bacterial nucleases; interplay between mRNA polyadenylation, translation and decay in prokaryotes and prokaryotic organelles; and RNA interference and other RNA mediators of gene expression. In addition to the talks and two poster sessions, there were three round tables: (1) Does translation occur in the nucleus? (2) Differences and similarities in the mechanisms of mRNA decay in different eukaryotes, and (3) RNA surveillance in bacteria?
Date: December 1, 2002
Creator: Maquat, Lynne
Partner: UNT Libraries Government Documents Department

DUAL PHASE MEMBRANE FOR HIGH TEMPERATURE CO2 SEPARATION

Description: This project is aimed at synthesis of a new inorganic dual-phase carbonate membrane for high temperature CO{sub 2} separation. Metal-carbonate dual-phase membranes were prepared by the direct infiltration method and the synthesis conditions were optimized. The dual-phase membranes are gas-tight with helium permeance about six orders of magnitude lower than that for the metal support. Efforts were made to test seals for permeation and separation experiments for dual-phase membrane at the intermediate temperature range (about 500 C) under oxidizing atmosphere. An effective new permeation cell with a metal seal was designed, fabricated and tested. The permeation setup provided leak-free sealing for the dual-phase membranes under the desired operation conditions. Though the reliable data showing high permeance for carbon dioxide with oxygen for the prepared metal-carbonate dual phase membrane has not been measured, the research efforts in improving membrane synthesis and setting up a new permeation cell with suitable seal have made it closer for one to demonstrate good dual-phase membranes for high temperature carbon dioxide separation. Research efforts were also directed towards preparation of a new ceramic-carbonate dual-phase membrane. Porous lanthanum cobaltite (LC) perovskite type oxide ceramic support with oxidation resistance better than the metal support and high electronic conductivity (1300-1500 S/cm in 400-600 C), was prepared and studied as an alternative support for the dual-phase carbonate membranes. The LC powder was found not reactive with the carbonate at 600 C. The porous LC disks have helium permeance and pore diameter smaller than the metal support but larger than the common {alpha}-alumina support. These results show promise to use the LC support for preparation of oxidation resistant dual-phase carbonate membranes.
Date: December 1, 2002
Creator: Lin, Jerry Y.S.
Partner: UNT Libraries Government Documents Department