Progress in heavy ion driven inertial fusion energy: From scaledexperiments to the integrated research experiment (open access)

Progress in heavy ion driven inertial fusion energy: From scaledexperiments to the integrated research experiment

The promise of inertial fusion energy driven by heavy ion beams requires the development of accelerators that produce ion currents ({approx}100s Amperesheam) and ion energies ({approx}1-10 GeV) that have not been achieved simultaneously in any existing accelerator. The high currents imply high generalized perveances, large tune depressions. and high space charge potentials of the beam center relative to the beam pipe. Many of the scientific issues associated with ion beams of high perveance and large tune depression have been addressed over the last two decades on scaled experiments at Lawrence Berkeley and Lawrence Livermore National Laboratories, the University of Maryland, and elsewhere. The additional requirement of high space charge potential (or equivalently high line charge density) gives rise to effects (particularly the role of electrons in beam transport) which must be understood before proceeding to a large scale accelerator. The first phase of a new series of experiments in Heavy Ion Fusion Virtual National Laboratory (HIF VNL), the High Current Experiments (HCX), is now being constructed at LBNL. The mission of the HCX will be to transport beams with driver line charge density so as to investigate the physics of this regime, including constraints on the maximum radial filling factor …
Date: June 22, 2001
Creator: Barnard, J. J.; Ahle, L. E.; Baca, D.; Bangerter, R. O.; Bieniosek, F. M.; Celata, C. M. et al.
Object Type: Article
System: The UNT Digital Library
Stability of High-Level Radioactive Waste Forms (open access)

Stability of High-Level Radioactive Waste Forms

High-level waste (HLW) glass compositions, processing schemes, limits on waste content, and corrosion/dissolution release models are dependent on an accurate knowledge of melting temperatures and thermochemical values. Unfortunately, existing models for predicting these temperatures are empirically-based, depending on extrapolations of experimental information. In addition, present models of leaching behavior of glass waste forms use simplistic assumptions or experimentally measured values obtained under non-realistic conditions. There is thus a critical need for both more accurate and more widely applicable models for HLW glass behavior, which this project addressed. Significant progress was made in this project on modeling HLW glass. Borosilicate glass was accurately represented along with the additional important components that contain iron, lithium, potassium, magnesium, and calcium. The formation of crystalline inclusions in the glass, an issue in Hanford HLW formulations, was modeled and shown to be predictive. Thus the results of this work have already demonstrated practical benefits with the ability to map compositional regions where crystalline material forms, and therefore avoid that detrimental effect. With regard to a fundamental understanding, added insights on the behavior of the components of glass have been obtained, including the potential formation of molecular clusters. The EMSP project had very significant effects beyond …
Date: June 22, 2001
Creator: Besmann, T.M.
Object Type: Report
System: The UNT Digital Library
Phenomenological two-gap model for the specific heat of MgB2 (open access)

Phenomenological two-gap model for the specific heat of MgB2

The authors show that the specific heat of the superconductor MgB{sub 2} in zero field, for which significant non-BCS features have been reported, can be fitted, essentially within experimental error, over the entire range of temperature to T{sub c} by a phenomenological two-gap model. The resulting gap parameters agree with previous determinations from band-structure calculations, and from various spectroscopic experiments. The determination from specific heat, a bulk property, shows that the presence of two superconducting gaps in MgB{sub 2} is a volume effect.
Date: June 22, 2001
Creator: Bouquet, F.; Wang, Y.; Fisher, R. A.; Hinks, D. G.; Jorgensen, J. D.; Junod, A. et al.
Object Type: Article
System: The UNT Digital Library
Comparison of Proposed Charitable Choice Act of 2001 with Current Charitable Choice Law (open access)

Comparison of Proposed Charitable Choice Act of 2001 with Current Charitable Choice Law

This report provides a side-by-side comparison of the charitable choice provisions of H.R. 7 with those of the 1996 welfare reform law (P.L. 104-193) and of later laws that extended charitable choice rules to the Community Services Block Grant Act (P.L. 105-285) and to substance abuse treatment and prevention services under the Public Health Service Act (P.L 106-310 and P.L. 106-554).
Date: June 22, 2001
Creator: Burke, Vee
Object Type: Report
System: The UNT Digital Library
Analysis of low energy AGS polarimeter data and potential consequences for RHIC spin physics. (open access)

Analysis of low energy AGS polarimeter data and potential consequences for RHIC spin physics.

The small asymmetries measured at G{sub {gamma}} = 7.5 during the RHIC spin commissioning were a serious concern. In earlier runs, asymmetries double those from the spin commissioning time (September 2000) had sometimes been observed, and there had been few changes to the AGS polarimeter hardware or operating conditions. Recently, the observed changes in the asymmetries measured at G{sub {gamma}} = 7:5 have been ascribed to contamination of the carbon target asymmetry with that from the fishline target and vice-versa, because of the sizeable beam spot size compared to the separation of the targets. This note addresses this hypothesis using the observed asymmetries. This problem could directly impact spin physics at RHIC.
Date: June 22, 2001
Creator: Cadman, R.; Krueger, K.; Spinka, H.; Underwood, D.; Yokosawa, A. & Huang, H.
Object Type: Report
System: The UNT Digital Library
Carbon Resistor Pressure Gauge Calibration at Low Stresses (open access)

Carbon Resistor Pressure Gauge Calibration at Low Stresses

The 470 Ohm carbon resistor gauge has been used in the stress range up to approximately 4-5 GPa for highly heterogeneous materials and/or divergent flow experiments. The attractiveness of the gauge is due to its rugged nature, simple construction, low cost, reproducibility, and survivability in dynamic events. The associated drawbacks are a long time response to pressure equilibration and gauge resistance hysteresis. In the range below 0.4 GPa, the gauge calibration has been mainly extrapolated into this regime. Because of the need for calibration data within this low stress regime, calibration experiments were performed using a split-Hopkinson bar, drop tower apparatus, and a gas pressure chamber. Since the performance of the gauge at elevated temperatures is a concern, the change in resistance due to heating at atmospheric pressure was also investigated. Details of the various calibration arrangements and the results will be discussed and compared a calibration curve fit to previously published calibration data.
Date: June 22, 2001
Creator: Cunningham, B; Vandersall, K S; Niles, A M; Greenwood, D W; Garcia, F & Forbes, J W
Object Type: Article
System: The UNT Digital Library
Engineering analysis for disposal of depleted uranium tetrafluoride (UF{sub 4}). (open access)

Engineering analysis for disposal of depleted uranium tetrafluoride (UF{sub 4}).

This report presents and evaluates options for disposing of depleted uranium in the chemical form of uranium tetrafluoride (UF{sub 4}). Two depleted uranium inventories are considered. One results from the original U.S. Department of Energy (DOE) inventory of 560,000 metric tons (te) of depleted uranium hexafluoride (UF{sub 6}); the other inventory is the original DOE inventory augmented by 145,000 te of depleted UF{sub 6} from the United States Enrichment Corporation. Preconceptual designs are included for three disposal options: disposal in a vault, disposal in an engineered trench, and disposal in a deep mine cavity. The disposal container is taken to be either a 30-gallon drum or a 55-gallon drum. Descriptions of the facilities associated with the three disposal options are provided. Staffing estimates for the construction and operation of the facilities are also provided. Wastes and emissions from the facilities during construction, operation, and maintenance have been estimated. Parametric studies have also been performed on the basis of 25% and 50% of the original inventory.
Date: June 22, 2001
Creator: Folga, S. M. & Kier, P. H.
Object Type: Report
System: The UNT Digital Library
FEA Analysis of AP-0 Target Hall Collection Lens (Current Design) (open access)

FEA Analysis of AP-0 Target Hall Collection Lens (Current Design)

The AP-0 Target Hall Collection Lens is a pulsed device which focuses anti-protons just downstream of the Target. Since the angles at which the anti-protons depart the Target can be quite large, a very high focusing strength is required to maximize anti-proton capture into the downstream Debuncher Ring. The current design of the Collection Lens was designed to operate with a focusing gradient of 1,000 T/m. However, multiple failures of early devices resulted in lowering the normal operating gradient to about 750 T/m. At this gradient, the Lens design fares much better, lasting several million pulses, but ultimately still fails. A Finite Element Analysis (FEA) has been performed on this Collection Lens design to help determine the cause and/or nature of the failures. The Collection Lens magnetic field is created by passing high current through a central conductor cylinder. A uniform current distribution through the cylinder will create a tangential or azimuthal magnetic field that varies linearly from zero at the center of the cylinder to a maximum at the outer surface of the cylinder. Anti-proton particles passing through this cylinder (along the longitudinal direction) will see an inward focusing kick back toward the center of the cylinder proportional to …
Date: June 22, 2001
Creator: Hurh, P.G. & Tang, Z.
Object Type: Report
System: The UNT Digital Library
Strategies and Technology for Managing High-Carbon Ash (open access)

Strategies and Technology for Managing High-Carbon Ash

The overall objective of the present project is to identify and assess strategies and solutions for the management of industry problems related to carbon in ash. Specific research issues to be addressed include: (1) the effect of parent fuel selection on ash properties and adsorptivity, including a first ever examination of the air entrainment behavior of ashes from alternative (non-coal) fuels; (2) the effect of various low-NOx firing modes on ash properties and adsorptivity; and (3) the kinetics and mechanism of ash ozonation. This data will provide scientific and engineering support of the ongoing process development activities. This first project period, experiments were carried out to better understand the fundamental nature of the ozonation effect on ash. Carbon surfaces were characterized by surfactant adsorption, and by X-ray Photoelectron Spectroscopy before and after oxidation, both by air at 440 C and by ozone at room temperature. The results strongly suggest that the beneficial effect of ozonation is in large part due to chemical modification of the carbon surfaces.
Date: June 22, 2001
Creator: Hurt, Robert; Suuberg, Eric & Veranth, John
Object Type: Report
System: The UNT Digital Library
Amendments Relating to the Discipline of Children with Disabilities in H.R. 1 and S.1, 107th Congress (open access)

Amendments Relating to the Discipline of Children with Disabilities in H.R. 1 and S.1, 107th Congress

This report discusses the Better Education for Students and Teachers Act, which would eliminate the requirement for educational services to children with disabilities in certain situations.
Date: June 22, 2001
Creator: Jones, Nancy Lee
Object Type: Report
System: The UNT Digital Library
Microalgae Production from Power Plant Flue Gas: Environmental Implications on a Life Cycle Basis (open access)

Microalgae Production from Power Plant Flue Gas: Environmental Implications on a Life Cycle Basis

Power-plant flue gas can serve as a source of CO{sub 2} for microalgae cultivation, and the algae can be cofired with coal. This life cycle assessment (LCA) compared the environmental impacts of electricity production via coal firing versus coal/algae cofiring. The LCA results demonstrated lower net values for the algae cofiring scenario for the following using the direct injection process (in which the flue gas is directly transported to the algae ponds): SOx, NOx, particulates, carbon dioxide, methane, and fossil energy consumption. Carbon monoxide, hydrocarbons emissions were statistically unchanged. Lower values for the algae cofiring scenario, when compared to the burning scenario, were observed for greenhouse potential and air acidification potential. However, impact assessment for depletion of natural resources and eutrophication potential showed much higher values. This LCA gives us an overall picture of impacts across different environmental boundaries, and hence, can help in the decision-making process for implementation of the algae scenario.
Date: June 22, 2001
Creator: Kadam, K. L.
Object Type: Report
System: The UNT Digital Library
Using Data Mining to Find Bent-Double Radio Galaxies in the FIRST Survey (open access)

Using Data Mining to Find Bent-Double Radio Galaxies in the FIRST Survey

In this paper, the authors describe the use of data mining techniques to search for radio-emitting galaxies with a bent-double morphology. In the past, astronomers from the FIRST (Faint Images of the Radio Sky at Twenty-cm) survey identified these galaxies through visual inspection. This was not only subjective but also tedious as the on-going survey now covers 8000 square degrees, with each square degree containing about 90 galaxies. In this paper, they describe how data mining can be used to automate the identification of these galaxies. They discuss the challenges faced in defining meaningful features that represent the shape of a galaxy and their experiences with ensembles of decision trees for the classification of bent-double galaxies.
Date: June 22, 2001
Creator: Kamath, C.; Cantu-Paz, E.; Fodor,I & Tang,N A
Object Type: Article
System: The UNT Digital Library
Failure Modes in High-Power Lithium-Ion Batteries for Use in Hybrid Electric Vehicles (open access)

Failure Modes in High-Power Lithium-Ion Batteries for Use in Hybrid Electric Vehicles

The Advanced Technology Development (ATD) Program seeks to aid the development of high-power lithium-ion batteries for hybrid electric vehicles. Nine 18650-size ATD baseline cells were tested under a variety of conditions. The cells consisted of a carbon anode, LiNi{sub 0.8}Co{sub 0.2}O{sub 2} cathode and DEC-EC-LiPF{sub 6} electrolyte, and they were engineered for high-power applications. Selected instrumental techniques such as synchrotron IR microscopy, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, gas chromatography, etc. were used to characterize the anode, cathode, current collectors and electrolyte from these cells. The goal was to identify detrimental processes which lead to battery failure under a high-current cycling regime as well as during storage at elevated temperatures. The diagnostic results suggest that the following factors contribute to the cell power loss: (a) SEI deterioration and non-uniformity on the anode, (b) morphology changes, increase of impedance and phase separation on the cathode, (c) pitting corrosion on the cathode Al current collector, and (d) decomposition of the LiPF{sub 6} salt in the electrolyte at elevated temperature.
Date: June 22, 2001
Creator: Kostecki, R.; Zhang, X.; Ross, Phillip N., Jr.; Kong, F.; Sloop, S.; Kerr, J. B. et al.
Object Type: Report
System: The UNT Digital Library
Nanometer-scale electrochemical patterning of LiMn2O4 surfaces by an atomic force microscope operating in air (open access)

Nanometer-scale electrochemical patterning of LiMn2O4 surfaces by an atomic force microscope operating in air

Electrochemical nanometer-scale patterning of the surface of a conducting lithium manganese oxide (LiMn{sub 2}O{sub 4}) by scanning probe microscopy (SPM) was studied. The ability to produce nanometer-size patterns of chemically modified oxide or nanometer-sized alterations of the oxide morphology is demonstrated and discussed with reference to possible mechanisms. It is demonstrated that unlike the SPM-based surface oxidation of metals and semiconductors, the LiMn{sub 2}O{sub 4} surface is altered via electrochemically generated species. We show that a localized surface chemical change can be confined to a depth which depends on the oxide-tip voltage difference and ambient humidity. In situ Raman microscopy measurements of localized electrochemical reaction products suggest complex mechanisms of processes induced at the LiMn{sub 2}O{sub 4} surface, such as delithiation through Li-proton exchange and disproportionation of LiMn{sub 2}O{sub 4} to MnO{sub 2} and soluble Mn{sup 2+} species.
Date: June 22, 2001
Creator: Kostecki, Robert; Bonhomme, Frederic; Servant, Laurent; Argoul, Francoise & McLarnon, Frank
Object Type: Report
System: The UNT Digital Library
Interfacial phenomena on selected cathode materials (open access)

Interfacial phenomena on selected cathode materials

We have carried out a series of surface studies of selected cathode materials. Instrumental techniques such as Raman microscopy, surface enhanced Raman spectroscopy (SERS), and atomic force microscopy were used to investigate the cathode surfaces. The goal of this study was to identify detrimental processes which occur at the electrode/electrolyte interface and can lead to electrode degradation and failure during cycling and/or storage at elevated temperatures.
Date: June 22, 2001
Creator: Kostecki, Robert; Matsuo, Yoshiaki & McLarnon, Frank
Object Type: Report
System: The UNT Digital Library
Carbon microstructures for electrochemical studies (open access)

Carbon microstructures for electrochemical studies

Thin layers of photoresist were spin coated onto silicon wafers, and then carbonized to form smooth carbon films by heating in nitrogen for 1 hour at temperatures between 600 to 1100 C. Well-defined carbon microstructures on Si wafers that are being considered for electrodes in a microbattery concept were obtained by additional processing steps involving patterning and lithography of the photoresist prior to carbonization. The status of the fabrication of carbon microelectrodes obtained by pyrolysis of photoresist, characterization of the carbons by surface-sensitive techniques and electrochemical analysis by cyclic voltammetry of the I{sup -}/I{sub 3}{sup -} redox reaction is described.
Date: June 22, 2001
Creator: Kostecki, Robert; Song, Xiang Yun & Kinoshita, Kim
Object Type: Report
System: The UNT Digital Library
Nanoscale fabrication and modification of selected battery materials (open access)

Nanoscale fabrication and modification of selected battery materials

Carbon is an integral part of many battery electrodes. We explored the use of semiconductor-processing techniques that involve photolithography to pattern photoresists and subsequent pyrolysis to form carbon microstructures that function as microelectrodes. In this study, we describe the status of the fabrication of carbon microelectrodes obtained by pyrolysis of photoresist. Electrochemical nanometer-scale patterning of the surface of a conducting lithium manganese oxide (LiMn{sub 2}O{sub 4}) by scanning probe microscopy (SPM) was studied. We show that a localized surface chemical change can be confined to a depth which depends on the oxide-tip voltage difference and ambient humidity The ability to produce nanometer-size patterns of chemically modified oxide or nanometer-sized alterations of the oxide morphology is demonstrated and discussed with reference to possible mechanisms.
Date: June 22, 2001
Creator: Kostecki, Robert; Song, Xiang Yun; Kinoshita, Kim & McLarnon, Frank
Object Type: Report
System: The UNT Digital Library
RF systems for the betatron-node scheme experiment at LBNL (open access)

RF systems for the betatron-node scheme experiment at LBNL

Two-beam accelerators based upon relativistic klystrons (RK's) have been proposed as power sources for future generation electron-positron linear colliders. These drivers are known to suffer from several transverse beam-breakup (BBU) instabilities. A program to study a particular technique (the 'betatron node scheme') of ameliorating the high frequency BBU is under way at LBL. Central to this study are the pillbox RF cavities and RF beam position monitors (BPM's) employed. This paper discusses the design, fabrication, and testing of the RF components. Details of the signal processing and analysis will be presented.
Date: June 22, 2001
Creator: Lidia, Steven M.; De Santis, Stefano & Houck, Timothy
Object Type: Article
System: The UNT Digital Library
Particle production and radiation environment at a neutrino factory target station (open access)

Particle production and radiation environment at a neutrino factory target station

Efficient production and collection of a large number of muons is needed to make a neutrino factory based on a muon storage ring viable. The results of extensive MARS simulations are reported for Megawatt proton beams on a carbon rod and mercury jet in a 20-T hybrid solenoid, followed by a matching section and decay channel. Beam energy and power in a 2 to 30 GeV range, beam spot size, beam and target tilt angle, target material and dimensions, and capture system parameters are optimized to get maximum muon yields at the end of the decay channel. Other particles transported down the beam line are also studied for the purpose of beam instrumentation. Prompt and residual radiation distributions are calculated and analysis of target integrity, quench stability and dynamic heat load to the superconducting coils, radiation damage and activation of materials near the beam is performed. Absorption of showers in the direction of a primary beam is considered.
Date: June 22, 2001
Creator: Mokhov, Nikolai V.
Object Type: Article
System: The UNT Digital Library
Beam-induced energy deposition in muon storage rings (open access)

Beam-induced energy deposition in muon storage rings

Beam-induced radiation effects have been simulated for 20 and 50 GeV muon storage rings designed for a Neutrino Factory. It is shown that by appropriately shielding the superconducting magnets, quench stability, acceptable dynamic heat loads, and low residual dose rates can be achieved. Alternatively, if a specially-designed skew focusing magnet without superconducting coils on the magnet's mid-plane is used, then the energy is deposited preferentially in the warm iron yoke or outer cryostat layers and internal shielding may not be required. In addition to the component irradiation analysis, shielding studies have been performed. Calculations of the external radiation were done for both designs but the internal energy deposition calculations for the 20 GeV Study-2 lattice are still in progress.
Date: June 22, 2001
Creator: Mokhov, Nikolai V.; Johnstone, Carol J. & Parker, Brett
Object Type: Article
System: The UNT Digital Library
Higgs searches at the Tevatron (open access)

Higgs searches at the Tevatron

This paper describes the searches for the Higgs boson performed by the CDF and DO collaborations at the Tevatron p{bar p} Collider using the data collected in the 1992-95 run. Searches for standard model Higgs and as well for neutral and charged minimal SUSY Higgs bosons are also presented. No signal has been observed and limits are set for production cross sections.
Date: June 22, 2001
Creator: Moneta, L.
Object Type: Article
System: The UNT Digital Library
Experimental Design for Laser Produced Shocks in Diamond Anvil Cells (open access)

Experimental Design for Laser Produced Shocks in Diamond Anvil Cells

Laser driven shock measurements have been performed on pre-compressed samples. A diamond anvil cell (DAC) has been used to statically compress water to 1 GPa and then strong shocked with an energetic laser. The use of intense laser irradiation can drive shocks in targets making it possible to study the equation of state (EOS) of samples well into the hundreds of GPQ regime. Generally, such experiments employ a sample initially at normal density and standard pressure. Therefore providing data on the principal Hugoniot. In this experiment the initial state of the sample was varied to provide data off the principal Hugoniot. We report the work that was done on the Vulcan laser and describe a method to achieve off principal Hugoniot data.
Date: June 22, 2001
Creator: Moon, S. J.; Cauble, R.; Collins, G. W.; Celliers, P. M.; Hicks, D.; Da Silva, L. B. et al.
Object Type: Article
System: The UNT Digital Library
GOEMON, a C++ library for accelerator modeling and analysis (open access)

GOEMON, a C++ library for accelerator modeling and analysis

Goemon is a C++ library that supersedes Tracy 2 written in Pascal. It has been continuously developed at ALS since 1993. This paper describes its design and implementation issues, and applications.
Date: June 22, 2001
Creator: Nishimura, Hiroshi
Object Type: Article
System: The UNT Digital Library
Scalable Unix commands for parallel processors : a high-performance implementation. (open access)

Scalable Unix commands for parallel processors : a high-performance implementation.

We describe a family of MPI applications we call the Parallel Unix Commands. These commands are natural parallel versions of common Unix user commands such as ls, ps, and find, together with a few similar commands particular to the parallel environment. We describe the design and implementation of these programs and present some performance results on a 256-node Linux cluster. The Parallel Unix Commands are open source and freely available.
Date: June 22, 2001
Creator: Ong, E.; Lusk, E. & Gropp, W.
Object Type: Article
System: The UNT Digital Library