Fundamental nucleon-nucleon interaction: probing exotic nuclear structure using GEANIE at LANCE/WNR (open access)

Fundamental nucleon-nucleon interaction: probing exotic nuclear structure using GEANIE at LANCE/WNR

The initial goal of this project was to study the in-medium nucleon-nucleon interaction by testing the fundamental theory of nuclear structure, the shell model, for nuclei between {sup 8}Zr and {sup 100}Sn. The shell model predicts that nuclei with ''magic'' (2,8,20,28,40,50, and 82) numbers of protons or neutrons form closed shells in the same fashion as noble gas atoms [may49]. A ''doubly magic'' nucleus with a closed shell of both protons and neutrons has an extremely simple structure and is therefore ideal for studying the nucleon-nucleon interaction. The shell model predicts that doubly magic nuclei will be spherical and that they will have large first-excited-state energies ({approx} 1 to 3 MeV). Although the first four doubly-magic nuclei exhibit this behavior, the N = Z = 40 nucleus, {sup 80}Zr, has a very low first-excited-state energy (290 keV) and appears to be highly deformed. This breakdown is attributed to the small size of the shell gap at N = Z = 40. If this description is accurate, then the N = Z = 50 doubly magic nucleus, {sup 100}Sn, will exhibit ''normal'' closed-shell behavior. The unique insight provided by doubly-magic nuclei from {sup 80}Zr to {sup 100}Sn has made them the …
Date: February 25, 2000
Creator: Bernstein, L
Object Type: Report
System: The UNT Digital Library
Evaluation of the Potential for Agricultural Development at the Hanford Site (open access)

Evaluation of the Potential for Agricultural Development at the Hanford Site

By 2050, when cleanup of the Hanford Site is expected to be completed, large worldwide demands to increase the global production of animal and fish protein, food, and fiber are anticipated, despite advancements in crop breeding, genetic engineering, and other technologies. The most likely large areas for expanded irrigation in the Pacific Northwest are the undeveloped East High areas of the Columbia Basin Project and non-restricted areas within the Hanford Site in south-central Washington State. The area known as the Hanford Site has all the components that favor successful irrigated farming. Constraints to agricultural development of the Hanford Site are political and social, not economic or technical. Obtaining adequate water rights for any irrigated development will be a major issue. Numerous anticipated future advances in irrigation and resource conservation techniques such as precision agriculture techniques, improved irrigation systems, and irrigation system controls will greatly minimize the negative environmental impacts of agricultural activities.
Date: February 25, 2000
Creator: Evans, Robert G.; Hattendorf, Mary J. & Kincaid, Charles T.
Object Type: Report
System: The UNT Digital Library
WIPP Facility Work Plan for Solid Waste Management Units (open access)

WIPP Facility Work Plan for Solid Waste Management Units

This Facility Work Plan (FWP) has been prepared as required by Module VII,Section VII.M.1 of the Waste Isolation Pilot Plant (WIPP) Hazardous Waste Permit, NM4890139088-TSDF (the Permit); (NMED, 1999a). This work plan describes the programmatic facility-wide approach to future investigations at Solid Waste Management Units (SWMUs) and Areas of Concern (AOCs) specified in the Permit. This FWP addresses the current Permit requirements. It uses the results of previous investigations performed at WIPP and expands the investigations as required by the Permit. As an alternative to the Resource Conservation and Recovery Act (RCRA) Facility Investigation (RFI) specified in Module VII of the Permit, current New Mexico Environment Department (NMED) guidance identifies an Accelerated Corrective Action Approach (ACAA) that may be used for any SWMU or AOC (NMED, 1998). This accelerated approach is used to replace the standard RFI Work Plan and Report sequence with a more flexible decision-making approach. The ACAA process allows a Facility to exit the schedule of compliance contained in the Facility’s Hazardous and Solid Waste Amendments (HSWA) permit module and proceed on an accelerated time frame. Thus, the ACAA process can be entered either before or after an RFI Work Plan. According to NMED’s guidance, a facility …
Date: February 25, 2000
Creator: Westinghouse TRU Solutions LLC
Object Type: Report
System: The UNT Digital Library
Fast Gate: Subnanosecond Gate Detectors for Laser Radiography (open access)

Fast Gate: Subnanosecond Gate Detectors for Laser Radiography

X-ray radiography is used as a principal diagnostic in a wide range of hydrodynamic tests relevant to the weapons program and also for basic materials and equation-of-state science studies. The quality of the x-ray radiograph can be significantly degraded by the scattering of x-rays within the object and by components of the test system itself. Elimination of these scattered x-rays from the recorded images can either substantially improve the image contrast and signal-to-noise or allow smaller, lower-cost x-ray sources to be used. The scattered x-rays could be minimized through the use of a much shorter-duration x-ray pulse and a fast, gated detector. The short duration x-ray pulse and the fast gated detector allow detection of only those x-rays which pass through the object being radiographed. X-rays which are the result of scattering have longer path lengths and take longer to reach the target. Most of these can be eliminated if the detector if gated off before they arrive at the detector. Until recently there were no sources of high energy x-rays (1-10 MeV) with short duration (sub 100 picosecond) pulses. Now the Petawatt Laser Facility (ref 1) at Lawrence Livermore National Laboratory has been able to produce 0.1 rads at …
Date: February 25, 2000
Creator: Trebes, J.; Feit, M.; Hatchett, S.; Key, M.; Phillips, T.; Sefcik, J. et al.
Object Type: Report
System: The UNT Digital Library
Intense Laser - Electron Beam Interactions (open access)

Intense Laser - Electron Beam Interactions

Applicants seeking a Certificate of Compliance for an Independent Spent Fuel Storage Installation (ISFSI) cask must evaluate the consequences of a handling accident resulting in a drop or tip-over of the cask onto a concrete storage pad. As a result, analytical modeling approaches that might be used to evaluate the impact of cylindrical containers onto concrete pads are needed. One such approach, described and benchmarked in NUREG/CR-6608,{sup 1} consists of a dynamic finite element analysis using a concrete material model available in DYNA3D{sup 2} and in LS-DYNA,{sup 3} together with a method for post-processing the analysis results to calculate the deceleration of a solid steel billet when subjected to a drop or tip-over onto a concrete storage pad. The analysis approach described in NUREG/CR-6608 gives a good correlation of analysis and test results. The material model used for the concrete in the analyses in NUREG/CR-6608 is, however, somewhat troublesome to use, requiring a number of material constants which are difficult to obtain. Because of this a simpler approach, which adequately evaluates the impact of cylindrical containers onto concrete pads, is sought. Since finite element modeling of metals, and in particular carbon and stainless steel, is routinely and accurately accomplished with …
Date: February 25, 2000
Creator: Cowan, T.; Ditmire, T. & LeSage, G.
Object Type: Report
System: The UNT Digital Library
Wavelets on Planar Tesselations (open access)

Wavelets on Planar Tesselations

We present a new technique for progressive approximation and compression of polygonal objects in images. Our technique uses local parameterizations defined by meshes of convex polygons in the plane. We generalize a tensor product wavelet transform to polygonal domains to perform multiresolution analysis and compression of image regions. The advantage of our technique over conventional wavelet methods is that the domain is an arbitrary tessellation rather than, for example, a uniform rectilinear grid. We expect that this technique has many applications image compression, progressive transmission, radiosity, virtual reality, and image morphing.
Date: February 25, 2000
Creator: Bertram, M.; Duchaineau, M.A.; Hamann, B. & Joy, K.I.
Object Type: Article
System: The UNT Digital Library
FFTF Authorization Agreement (open access)

FFTF Authorization Agreement

The purpose of the Authorization Agreement is to serve as a mechanism whereby the U.S. Department of Energy, Richland Operations Office (RL) and Fluor Hanford (FH) jointly clarify and agree to key conditions for conducting work safely and efficiently.
Date: February 25, 2000
Creator: Dautel, W. A.
Object Type: Report
System: The UNT Digital Library
Advancement and Refinement of HyperSoar Modeling (open access)

Advancement and Refinement of HyperSoar Modeling

This report discusses the topic of periodic cruise trajectories for hypersonic flight. An extensive review of previous work associated with periodic cruise trajectories for subsonic, supersonic and hypersonic flight is presented to provide the background for this investigation. The primary objective of this report is to discuss why periodic cruise trajectories lead to near fuel-optimal trajectories from a heuristic, mathematical and computational perspective with air breathing propulsion. Results to date indicate that periodic achieves greater fuel savings by exchanging kinetic and potential energy more efficiently. The vehicle attempts to chatter back and forth between where the vehicle wants to fly for optimum aerodynamic and propulsive performance. Results from computational simulations are inconclusive and require further work to define appropriate interfaces for aerodynamic and propulsion data decks for input into the POST software. The notional design of a vehicle to fly periodic hypersonic cruise trajectories was improved by including concepts for engine installation, flight controls and by including considerations for off-design performance. This notional design provides a better starting point for more serious and complete vehicle design studies.
Date: February 25, 2000
Creator: Carter, P. H., II; Pines, D. J. & vonEggers Rudd, L.
Object Type: Report
System: The UNT Digital Library
Project W-314 Specific Test and Evaluation Plan for 200E Waste Transfer System (open access)

Project W-314 Specific Test and Evaluation Plan for 200E Waste Transfer System

The purpose of this Specific Test and Evaluation Plan (STEP) is to provide a detailed written plan for the systematic testing of the newly constructed 200E Waste Transfer System in the W-314 Project. The STEP provides the outline for test and evaluation methods that verify the system's performance and compliance to the established Project design criteria. The STEP is a ''lower tier'' document based on the W-314 Test & Evaluation Plan (TEP).
Date: February 25, 2000
Creator: Hammers, Jack S.
Object Type: Report
System: The UNT Digital Library
Impurity Role In Mechanically Induced Defects (open access)

Impurity Role In Mechanically Induced Defects

An improved understanding of dislocation dynamics and interactions is an outstanding problem in the multi scale modeling of materials properties, and is the current focus of major theoretical efforts world wide. We have developed experimental and theoretical tools that will enable us to measure and calculate quantities defined by the defect structure. Unique to the measurements is a new spectroscopy that determines the detailed elemental composition at the defect site. The measurements are based on positron annihilation spectroscopy performed with a 3 MeV positron beam [1]. Positron annihilation spectroscopy is highly sensitive to dislocations and associated defects and can provide unique elements of the defect size and structure. Performing this spectroscopy with a highly penetrating positron beam enables flexibility in sample handling. Experiments on fatigued and stressed samples have been done and in situ measurement capabilities have been developed. We have recently performed significant upgrades to the accelerator operation and novel new experiments have been performed [2-4] To relate the spectrographic results and the detailed structure of a defect requires detailed calculations. Measurements are coupled with calculated results based on a description of positions of atoms at the defect. This gives an atomistic view of dislocations and associated defects including …
Date: February 25, 2000
Creator: Howell, R.H.; Asoka-Kumar, P.; Hartley, J. & Sterne, P.
Object Type: Report
System: The UNT Digital Library
Letter of Intent for RPP Characterization Program Process Engineering and Hanford Analytical Services and Characterization Project (open access)

Letter of Intent for RPP Characterization Program Process Engineering and Hanford Analytical Services and Characterization Project

The Characterization Project level of success achieved by the River Protection Project (RPP) is determined by the effectiveness of several organizations across RPP working together. The requirements, expectations, interrelationships, and performance criteria for each of these organizations were examined in order to understand the performances necessary to achieve characterization objectives. This Letter of Intent documents the results of the above examination. It formalizes the details of interfaces, working agreements, and requirements for obtaining and transferring tank waste samples from the Tank Farm System (RPP Process Engineering, Characterization Project Operations, and RPP Quality Assurance) to the characterization laboratory complex (222-S Laboratory, Waste Sampling and Characterization Facility, and the Hanford Analytical Service Program) and for the laboratory complex analysis and reporting of analytical results.
Date: February 25, 2000
Creator: Adams, M. R.
Object Type: Report
System: The UNT Digital Library
Application of Laboratory and Modeling Capabilities to Extreme Ultraviolet Spectroscopy of Astrophysical Sources (open access)

Application of Laboratory and Modeling Capabilities to Extreme Ultraviolet Spectroscopy of Astrophysical Sources

Work funded by the subject LDRD proposal has produced the following results. First, a comprehensive catalog of EUV lines from M-shell iron (Fe IX-XVI) in the 60-140 {angstrom} waveband. Second, a revised estimate of the radiative cooling of high-temperature plasmas by Fe, which dominates the cooling in cosmic-abundance plasmas from 4 x 10{sup 5}K to 1 x 10{sup 7}K. Third, laboratory data to correct theoretical atomic models and develop reliable spectral models of M-shell Fe in the EUV. Fourth, a solution of the origin of the quasi-continuum in EUV spectra of late-type stars, which has been variously ascribed to a high-temperature tail on the emission measure distribution of stellar coronae, reduced metal abundances, resonant scattering (destruction) of emission lines, and incompleteness of atomic models.
Date: February 25, 2000
Creator: Mauche, C.; Liedahl, D.A. & Beiersdorfer, P.
Object Type: Report
System: The UNT Digital Library
Phenomenology of the deuteron electromagnetic form factors (open access)

Phenomenology of the deuteron electromagnetic form factors

A rigorous extraction of the deuteron charge form factors from tensor polarization data in elastic electron-deuteron scattering, at given values of the 4-momentum transfer, is presented. Then the world data for elastic electron-deuteron scattering is used to parameterize, in three different ways, the three electromagnetic form factors of the deuteron in the 4-momentum transfer range 0-7 fm. This procedure is made possible with the advent of recent polarization measurements. The parameterizations allow a phenomenological characterization of the deuteron electromagnetic structure. They can be used to remove ambiguities in the form factors extraction from future polarization data.
Date: February 25, 2000
Creator: Abbott, David; Ahmidouch, Abdellah; Anklin, H.; Arvieux, J.; Ball, James P.; Beedoe, Shelton et al.
Object Type: Article
System: The UNT Digital Library
Advanced Algorithms for Rapidly Reconstructing Clandestine Releases of Biological Agents in Urban Areas (open access)

Advanced Algorithms for Rapidly Reconstructing Clandestine Releases of Biological Agents in Urban Areas

As the United States plays a greater role in the 21st Century as global peacekeeper and international defender of human rights and democratic principles, there is an increasing likelihood that it will become the focus of acts of terrorism. Such acts of terrorism--sometimes described as ''asymmetric''--could involve the threat or use of weapons of mass destruction (WMD), particularly those considered unconventional, which include ones designed to release chemical or biological agents. In fact, biological agents are of great concern because, as noted by D.A. Henderson of the Center for Civilian Biodefense Studies at Johns Hopkins University in Baltimore, MD, ''... with shortages of hospital space, vaccines, antibiotics, there would be chaos.'' (Williams, 2000). Unfortunately, potential aggressor nations, terrorist groups, and even individuals, can, for a modest cost and effort, develop covert capabilities for manufacturing, transporting, and offensively using biological weapons of mass destruction. Furthermore, there is evidence to indicate that terrorist increasingly are targeting civilian populations--in order to inflict indiscriminate casualties--as well as other more traditional targets such as symbolic buildings or organizations (see Tucker, 1999), which suggest that introducing rapid treatment after a biological event may be more practical than concentrating on prevention (see Siegrist, 1999), especially because sensors …
Date: February 25, 2000
Creator: Shinn, J. H.; Hall, C. H.; Neher, L. A.; Wilder, F. J.; Gouveia, D. W.; Layton, D. W. et al.
Object Type: Report
System: The UNT Digital Library
Modeling of Anisotropic Inelastic Behavior (open access)

Modeling of Anisotropic Inelastic Behavior

An experimental capability, developed at Lawrence Livermore National Laboratory (LLNL), is being used to study the yield behavior of elastic-plastic materials. The objective of our research is to develop better constitutive equations for polycrystalline metals. We are experimentally determining the multidimensional yield surface of the material, both in its initial state and as it evolves during large inelastic deformations. These experiments provide a more complete picture of material behavior than can be obtained from traditional uniaxial tests. Experimental results show that actual material response can differ significantly from that predicted by simple idealized models. These results are being used to develop improved constitutive models of anisotropic plasticity for use in continuum computer codes.
Date: February 25, 2000
Creator: Nikkel, D. J.; Nath, D. S.; Brown, A. A. & Casey, J.
Object Type: Report
System: The UNT Digital Library
Project W-211 Initial Tank Retrieval Systems (ITRS) Description of Operations for 241-AZ-102 (open access)

Project W-211 Initial Tank Retrieval Systems (ITRS) Description of Operations for 241-AZ-102

The primary purpose of the Initial Tank Retrieval Systems (ITRS) is to provide systems for retrieval of radioactive wastes stored in underground double-shell tanks (DSTs) for transfer to alternate storage, evaporation, pretreatment or treatment, while concurrently reducing risks associated with safety watch list and other DSTs. This Description of Operation (DOO) defines the control philosophy for the waste retrieval system for Tank 241-AZ-102 (AZ-102). This DOO provides a basis for the detailed design of the Project W-211 Retrieval Control System (RCS) for AZ-102 and also establishes test criteria for the RCS.
Date: February 25, 2000
Creator: BRIGGS, S.R.
Object Type: Report
System: The UNT Digital Library
[Three-dimensional position-sensitive germanium detectors]. Annual report for EMSP Project Number 65015 (open access)

[Three-dimensional position-sensitive germanium detectors]. Annual report for EMSP Project Number 65015

This study focuses on the radioactive materials characterization needs of DOE's decontamination and decommissioning effort. Gamma-ray imaging and spectroscopy together form a potentially powerful tool for the passive, non-destructive and non-intrusive identification and spatial mapping of contaminated structures. Germanium position-sensitive gamma-ray detectors offer the advantage of excellent energy resolution required for clear isotopic identification combined with potentially high spatial resolution. The authors propose a program of research to develop three-dimensional position-sensitive germanium detectors with the ultimate goal of improving image resolution without cameras. With the addition of depth-of-interaction sensing to conventional two-dimensional position-sensitive detectors, they will be able to greatly reduce the image degradation effects caused by Compton scattering and parallax, thereby increasing the resolving power of the detectors. The technology developed will form the basis for the design and fabrication of future high-performance gamma-ray imaging cameras.
Date: February 25, 2000
Creator: Amman, Mark & Luke, Paul
Object Type: Report
System: The UNT Digital Library
Ceramicrete: A novel ceramic packaging system for spent-fuel transport and storage (open access)

Ceramicrete: A novel ceramic packaging system for spent-fuel transport and storage

This presentation summarizes efforts to develop and apply chemically bonded phosphate ceramic (Ceramicrete{trademark}) technology for radiation shielding applications. The specific application being targeted is a packaging system for spent-fuel transport and storage. Using Ceramicrete technology under ambient conditions, the authors can produce dense and hard ceramic forms that incorporate second-phase material. Ceramicrete inherently is a superior shielding material because it contains large amounts of bound water in its crystal structure and can be cast in any shape. A parametric study was conducted on Ceramicrete that contained second-phase additions of metals and other ceramic powders. Results of various standardized tests that included mechanical performance and shielding from neutrons are presented. The fabrication of complex shapes and structures by Ceramicrete technology is discussed. Ceramicrete is compared with other currently available shielding systems that are based on concrete and polymers.
Date: February 25, 2000
Creator: Singh, D.; Jeong, S. Y.; Dwyer, K. & Abesadze, T.
Object Type: Article
System: The UNT Digital Library
A high-charge high-brightness L-band photocathode RF gun (open access)

A high-charge high-brightness L-band photocathode RF gun

The Argonne Wakefield Accelerator has been successfully commissioned and used for conducting wakefield experiments in dielectric loaded structures and plasmas. Although the initial wakefield experiments were successful, higher drive beam quality would substantially improve the wakefield accelerating gradients. In this paper the authors present a new 1-1/2 cell L-band photocathode RF gun design. This gun will produce 10--100 nC beam with 2--5 ps ms pulse length and normalized emittance less than 100 mm mrad. The final gun design and numerical simulations of the beam dynamics are presented.
Date: February 25, 2000
Creator: Conde, M. E.; Gai, W.; Konecny, R.; Power, J. G.; Schoessow, P. & Sun, X.
Object Type: Article
System: The UNT Digital Library
An overview of the Nuclear Materials Focus Area research program (open access)

An overview of the Nuclear Materials Focus Area research program

The Nuclear Material Focus Area (NMFA) is responsible for providing comprehensive needs identification, integration of technology research and development activities, and technology deployment for stabilization, packaging, and interim storage of surplus nuclear materials within the DOE complex. The NMFA was chartered in April 1999 by the Office of Science and Technology (OST), an organizational component of the US Department of Energy's (DOE) Office of Environmental Management (EM). OST manages a national program to conduct basic and applied research, and technology development, demonstration, and deployment assistance that is essential to completing a timely and cost-effective cleanup of the DOE nuclear weapons complex. DOE/EM provides environmental research results, as well as cleanup technologies and systems, to meet high-priority end-user needs, reduce EM's major cost centers and technological risks, and accelerate technology deployments. The NMFA represents the segment of EM that focuses on technological solutions for re-using, transforming, and disposing excess nuclear materials and is jointly managed by the DOE Albuquerque Operations Office and the DOE Idaho Operations Office.
Date: February 25, 2000
Creator: Roberson, Gary D.; Polansky, Gary F.; Osborne, Ken K. & Randall, Virginia
Object Type: Article
System: The UNT Digital Library
Crystal diffraction lens for medical imaging (open access)

Crystal diffraction lens for medical imaging

A crystal diffraction lens for focusing energetic gamma rays has been developed at Argonne National Laboratory for use in medical imaging of radioactivity in the human body. A common method for locating possible cancerous growths in the body is to inject radioactivity into the blood stream of the patient and then look for any concentration of radioactivity that could be associated with the fast growing cancer cells. Often there are borderline indications of possible cancers that could be due to statistical functions in the measured counting rates. In order to determine if these indications are false or real, one must resort to surgical means and take tissue samples in the suspect area. They are developing a system of crystal diffraction lenses that will be incorporated into a 3-D imaging system with better sensitivity (factors of 10 to 100) and better spatial resolution (a few mm in both vertical and horizontal directions) than most systems presently in use. The use of this new imaging system will allow one to eliminate 90% of the false indications and both locate and determine the size of the cancer with mm precision. The lens consists of 900 single crystals of copper, 4 mm x 4 …
Date: February 25, 2000
Creator: Smither, R. K. & Roa, D. E.
Object Type: Article
System: The UNT Digital Library
Record of Technical Change {number_sign}1 to ''Corrective Action Investigation Plan for Corrective Action Unit 261: Test Cell A Leachfield System, Nevada Test Site, Nevada,'' Revision 0, DOE/NV-519 (open access)

Record of Technical Change {number_sign}1 to ''Corrective Action Investigation Plan for Corrective Action Unit 261: Test Cell A Leachfield System, Nevada Test Site, Nevada,'' Revision 0, DOE/NV-519

This Record of Technical Change provides updates to the technical information included in ''Corrective Action Investigation Plan for Corrective Action Unit 261: Test Cell A Leachfield System, Nevada Test Site, Nevada,'' DOE/NV--519.
Date: February 25, 2000
Creator: United States. Department of Energy. Nevada Operations Office.
Object Type: Report
System: The UNT Digital Library
Remedial investigation report for J-Field, Aberdeen Proving Ground, Maryland. Volume 3: Ecological risk assessment (open access)

Remedial investigation report for J-Field, Aberdeen Proving Ground, Maryland. Volume 3: Ecological risk assessment

The Environmental Management Division of the U.S. Army Aberdeen Proving Ground (APG), Maryland, is conducting a remedial investigation (RI) and feasibility study (FS) of the J-Field area at APG, pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended. As part of that activity, Argonne National Laboratory (ANL) conducted an ecological risk assessment (ERA) of the J-Field site. This report presents the results of that assessment.
Date: February 25, 2000
Creator: Hlohowskyj, I.; Hayse, J.; Kuperman, R. & Van Lonkhuyzen, R.
Object Type: Report
System: The UNT Digital Library
Monte Carlo source convergence and the Whitesides problem (open access)

Monte Carlo source convergence and the Whitesides problem

The issue of fission source convergence in Monte Carlo eigenvalue calculations is of interest because of the potential consequences of erroneous criticality safety calculations. In this work, the authors compare two different techniques to improve the source convergence behavior of standard Monte Carlo calculations applied to challenging source convergence problems. The first method, super-history powering, attempts to avoid discarding important fission sites between generations by delaying stochastic sampling of the fission site bank until after several generations of multiplication. The second method, stratified sampling of the fission site bank, explicitly keeps the important sites even if conventional sampling would have eliminated them. The test problems are variants of Whitesides' Criticality of the World problem in which the fission site phase space was intentionally undersampled in order to induce marginally intolerable variability in local fission site populations. Three variants of the problem were studied, each with a different degree of coupling between fissionable pieces. Both the superhistory powering method and the stratified sampling method were shown to improve convergence behavior, although stratified sampling is more robust for the extreme case of no coupling. Neither algorithm completely eliminates the loss of the most important fissionable piece, and if coupling is absent, the …
Date: February 25, 2000
Creator: Blomquist, R. N.
Object Type: Article
System: The UNT Digital Library