Measurement of sextupole orbit offsets in the APS storage ring. (open access)

Measurement of sextupole orbit offsets in the APS storage ring.

Horizontal orbit errors at the sextuples in the Advanced Photon Source (APS) storage ring can cause changes in tune and modulation of the beta functions around the ring. To determine the significance of these effects requires knowing the orbit relative to the magnetic center of the sextuples. The method considered here to determine the horizontal beam position in a given sextupole is to measure the tune shift caused by a change in the sextupole strength. The tune shift and a beta function for the same plane uniquely determine the horizontal beam position in the sextupole. The beta function at the sextupole was determined by propagating the beta functions measured at nearby quadrupoles to the sextupole location. This method was used to measure the sextupole magnetic center offset relative to an adjacent beam position monitor (BPM) at a number of sextupole locations. We report on the successes and problems of the method as well as an improved method.
Date: April 16, 1999
Creator: Borland, M.
Object Type: Article
System: The UNT Digital Library
Commercial viability of hybrid vehicles : best household use and cross national considerations. (open access)

Commercial viability of hybrid vehicles : best household use and cross national considerations.

Japanese automakers have introduced hybrid passenger cars in Japan and will soon do so in the US. In this paper, we report how we used early computer simulation model results to compare the commercial viability of a hypothetical near-term (next decade) hybrid mid-size passenger car configuration under varying fuel price and driving patterns. The fuel prices and driving patterns evaluated are designed to span likely values for major OECD nations. Two types of models are used. One allows the ''design'' of a hybrid to a specified set of performance requirements and the prediction of fuel economy under a number of possible driving patterns (called driving cycles). Another provides an estimate of the incremental cost of the hybrid in comparison to a comparably performing conventional vehicle. In this paper, the models are applied to predict the NPV cost of conventional gasoline-fueled vehicles vs. parallel hybrid vehicles. The parallel hybrids are assumed to (1) be produced at high volume, (2) use nickel metal hydride battery packs, and (3) have high-strength steel bodies. The conventional vehicle also is assumed to have a high-strength steel body. The simulated vehicles are held constant in many respects, including 0-60 time, engine type, aerodynamic drag coefficient, tire …
Date: July 16, 1999
Creator: Santini, D. J. & Vyas, A. D.
Object Type: Article
System: The UNT Digital Library
Dynamic signatures of driven vortex motion. (open access)

Dynamic signatures of driven vortex motion.

We probe the dynamic nature of driven vortex motion in superconductors with a new type of transport experiment. An inhomogeneous Lorentz driving force is applied to the sample, inducing vortex velocity gradients that distinguish the hydrodynamic motion of the vortex liquid from the elastic and-plastic motion of the vortex solid. We observe elastic depinning of the vortex lattice at the critical current, and shear induced plastic slip of the lattice at high Lorentz force gradients.
Date: September 16, 1999
Creator: Crabtree, G. W.; Kwok, W. K.; Lopez, D.; Olsson, R. J.; Paulius, L. M.; Petrean, A. M. et al.
Object Type: Article
System: The UNT Digital Library
Simulation of Grain Growth in a Near-Eutectic Solder Alloy (open access)

Simulation of Grain Growth in a Near-Eutectic Solder Alloy

Microstructural evolution due to aging of solder alloys determines their long-term reliability as electrical, mechanical and thermal interconnects in electronics packages. The ability to accurately determine the reliability of existing electronic components as well as to predict the performance of proposed designs depends upon the development of reliable material models. A kinetic Monte Carlo simulation was used to simulate microstructural evolution in solder-class materials. The grain growth model simulated many of the microstructural features observed experimentally in 63Sn-37Pb, a popular near-eutectic solder alloy. The model was validated by comparing simulation results to new experimental data on coarsening of Sn-Pb solder. The computational and experimental grain growth exponent for two-phase solder was found to be much lower than that for normal, single phase grain growth. The grain size distributions of solders obtained from simulations were narrower than that of normal grain growth. It was found that the phase composition of solder is important in determining grain growth behavior.
Date: December 16, 1999
Creator: TIKARE,VEENA & VIANCO,PAUL T.
Object Type: Article
System: The UNT Digital Library
Effects of Barometric Fluctuations on Well Water-Level Measurements and Aquifer Test Data (open access)

Effects of Barometric Fluctuations on Well Water-Level Measurements and Aquifer Test Data

The Pacific Northwest National Laboratory, as part of the Hanford Groundwater Monitoring Project, examines the potential for offsite migration of contamination within underlying aquifer systems. Well water-level elevation measurements from selected wells within these aquifer systems commonly form the basis for delineating groundwater-flow patterns (i.e., flow direction and hydraulic gradient). In addition, the analysis of water-level responses obtained in wells during hydrologic tests provides estimates of hydraulic properties that are important for evaluating groundwater-flow velocity and transport characteristics. Barometric pressure fluctuations, however, can have a discernible impact on well water-level measurements. These barometric effects may lead to erroneous indications of hydraulic head within the aquifer. Total hydraulic head (i.e., sum of the water-table elevation and the atmospheric pressure at the water-table surface) within the aquifer, not well water-level elevation, is the hydrologic parameter for determining groundwater-flow direction and hydraulic gradient conditions. Temporal variations in barometric pressure may also adversely affect well water-level responses obtained during hydrologic tests. If significant, adjustments or removal of these barometric effects from the test-response record may be required for quantitative hydraulic property determination. This report examines the effects of barometric fluctuations on well water-level measurements and evaluates adjustment and removal methods for determining areal aquifer …
Date: December 16, 1999
Creator: FA Spane, Jr.
Object Type: Report
System: The UNT Digital Library
Technological Challenges to X-Ray FELs (open access)

Technological Challenges to X-Ray FELs

There is strong interest in the development of x-ray free electron lasers (x-ray FELs). The interest is driven by the scientific opportunities provided by intense, coherent x-rays. An x-ray FEL has all the characteristics of a fourth-generation source: brightness several orders of magnitude greater than presently achieved in third-generation sources, full transverse coherence, and sub-picosecond long pulses. The SLAC and DESY laboratories have presented detailed design studies for X-Ray FEL user facilities around the 0.1 nm wavelength-regime (LCLS at SLAC, TESLA X-Ray FEL at DESY). Both laboratories are engaged in proof-of-principle experiments are longer wavelengths (TTF FEL Phase I at 71 nm, VISA at 600-800 nm) with results expected in 1999. The technologies needed to achieve the proposed performances are those of bright electron sources, of acceleration systems capable of preserving the brightness of the source, and of undulators capable of meeting the magnetic and mechanical tolerances that are required for operation in the SASE mode. This paper discusses the technological challenges presented by the X-Ray FEL projects.
Date: September 16, 1999
Creator: Nuhn, Heinz-Dieter
Object Type: Report
System: The UNT Digital Library
NSTX Electrical Power Systems (open access)

NSTX Electrical Power Systems

The National Spherical Torus Experiment (NSTX) has been designed and installed in the existing facilities at Princeton Plasma Physic Laboratory (PPPL). Most of the hardware, plant facilities, auxiliary sub-systems, and power systems originally used for the Tokamak Fusion Test Reactor (TFTR) have been used with suitable modifications to reflect NSTX needs. The design of the NSTX electrical power system was tailored to suit the available infrastructure and electrical equipment on site. Components were analyzed to verify their suitability for use in NSTX. The total number of circuits and the location of the NSTX device drove the major changes in the Power system hardware. The NSTX has eleven (11) circuits to be fed as compared to the basic three power loops for TFTR. This required changes in cabling to insure that each cable tray system has the positive and negative leg of cables in the same tray. Also additional power cabling had to be installed to the new location. The hardware had to b e modified to address the need for eleven power loops. Power converters had to be reconnected and controlled in anti-parallel mode for the Ohmic heating and two of the Poloidal Field circuits. The circuit for the Coaxial …
Date: December 16, 1999
Creator: Ilic, A.; Baker, E.; Hatcher, R.; Ramakrishnan, S. & al, et
Object Type: Report
System: The UNT Digital Library
Measurements of the electron cloud in the APS storage ring. (open access)

Measurements of the electron cloud in the APS storage ring.

Synchrotron radiation interacting with the vacuum chamber walls in a storage ring produce photoelectrons that can be accelerated by the beam, acquiring sufficient energy to produce secondary electrons in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, as is the case with the aluminum chambers in the Advanced Photon Source (APS) storage ring, a runaway condition can develop. As the electron cloud builds up along a train of stored positron or electron bunches, the possibility exists that a transverse perturbation of the head bunch will be communicated to trailing bunches due to interaction with the cloud. In order to characterize the electron cloud, a special vacuum chamber was built and inserted into the ring. The chamber contains 10 rudimentary electron-energy analyzers, as well as three targets coated with different materials. Measurements show that the intensity and electron energy distribution are highly dependent on the temporal spacing between adjacent bunches and the amount of current contained in each bunch. Furthermore, measurements using the different targets are consistent with what would be expected based on the SEY of the coatings. Data for both positron and electron beams are presented.
Date: April 16, 1999
Creator: Harkey, K. C.
Object Type: Article
System: The UNT Digital Library
Photovoltaic Energy Program Contract Summary; Fiscal Year 1998 (open access)

Photovoltaic Energy Program Contract Summary; Fiscal Year 1998

This document provides individual summaries of some 200 photovoltaics research projects performed in house and by subcontractors to Department of Energy national laboratories and field offices, including the National Renewable Energy Laboratory, Sandia National Laboratories, Golden Field Office, Brookhaven National Laboratory, Albuquerque Field Office, and Boston Support Office. The document is divided into the following sections: research and development, technology development, and systems engineering and applications. Three indexes are included: performing organizations by name, performing organizations by state, and performing organizations by technology area.
Date: February 16, 1999
Creator: Surek, T.
Object Type: Report
System: The UNT Digital Library
Direct Measurement of the Neutral Weak Dipole Moments of the tau Lepton (open access)

Direct Measurement of the Neutral Weak Dipole Moments of the tau Lepton

We present direct measurements of the neutral weak anomalous magnetic dipole moment, a{sub {tau}}{sup w}, and neutral weak electric dipole moment, d{sub {tau}}{sup w}, of the tau lepton. The dipole moments are measured by analyzing the decays of {tau} leptons produced in the annihilation of positrons and longitudinally polarized electrons on the Z boson resonance at the SLC. Using 6736 Z decays to {tau}{sup +} {tau}{sup {minus}} pairs elected from our 1993-1998 data sample we obtain Re(a{sub {tau}}{sup w}) = (0.26 {+-} 1.24) x 10{sup {minus}3}, Im(a{sub {tau}}{sup w}) = ({minus}0.02 {+-} 0.66) x 10{sup {minus}3}, Re(d{sub {tau}}{sup w}) = (0.18 {+-} 0.67) x 10 {sup {minus}17} e {center_dot} cm, and Im(D{sub {tau}}{sup w}) = ({minus}0.26 {+-} 0.37) x 10{sup {minus}17} e {center_dot} cm.
Date: July 16, 1999
Creator: Barklow, Tim
Object Type: Report
System: The UNT Digital Library
Integrated Micro-Optical Fluorescence Detection System for Microfluidic Electrochromatography (open access)

Integrated Micro-Optical Fluorescence Detection System for Microfluidic Electrochromatography

The authors describe the design and microfabrication of an extremely compact optical system as a key element in an integrated capillary-channel electrochromatograph with laser induced fluorescence detection. The optical design uses substrate-mode propagation within the fused silica substrate. The optical system includes a vertical cavity surface-emitting laser (VCSEL) array, two high performance microlenses and a commercial photodetector. The microlenses are multilevel diffractive optics patterned by electron beam lithography and etched by reactive ion etching in fused silica. Two generations of optical subsystems are described. The first generation design is integrated directly onto the capillary channel-containing substrate with a 6 mm separation between the VCSEL and photodetector. The second generation design separates the optical system onto its own module and the source to detector length is further compressed to 3.5 mm. The systems are designed for indirect fluorescence detection using infrared dyes. The first generation design has been tested with a 750 nm VCSEL exciting a 10{sup -4} M solution of CY-7 dye. The observed signal-to-noise ratio of better than 100:1 demonstrates that the background signal from scattered pump light is low despite the compact size of the optical system and meets the system sensitivity requirements.
Date: September 16, 1999
Creator: Allerman, Andrew A.; Arnold, Don W.; Asbill, Randolph E.; Bailey, Christopher G.; Carter, Tony Ray; Kemme, Shanalyn A. et al.
Object Type: Article
System: The UNT Digital Library
Polarization Asymmetries in gamma e Collisions and Triple Gauge Boson Couplings Revisited (open access)

Polarization Asymmetries in gamma e Collisions and Triple Gauge Boson Couplings Revisited

The capability of the NLC run in the {gamma}e collision mode to probe the CP-conserving {gamma}WW and {gamma}ZZ anomalous couplings through the use of the polarization asymmetry is reviewed. When combined with other measurements, very strong constraints on both varieties of anomalous couplings can be obtained. We show that these bounds are complementary to those that can be extracted from data taken at the LHC.
Date: July 16, 1999
Creator: Rizzo, Thomas G.
Object Type: Report
System: The UNT Digital Library
Microwave Imaging Reflectometry for the Visualization of Turbulence in Tokamaks (open access)

Microwave Imaging Reflectometry for the Visualization of Turbulence in Tokamaks

Understanding the mechanism of anomalous transport in magnetically confined plasmas requires the use of sophisticated diagnostic tools for the measurement of short-scale turbulent fluctuations. This paper describes the conceptual design of an experimental technique for the global visualization of density fluctuations in tokamaks. The proposed method is based on microwave reflectometry and consists in using a large diameter probing beam, collecting the reflected waves with a large aperture antenna, and forming an image of the reflecting plasma layer onto a 2D array of microwave receivers. Based on results from a series of numerical simulations, the theoretical feasibility conditions of the proposed method are discussed.
Date: December 16, 1999
Creator: Mazzucato, E.
Object Type: Report
System: The UNT Digital Library
Status of the first batch of niobium resonator production for the New Delhi booster linac. (open access)

Status of the first batch of niobium resonator production for the New Delhi booster linac.

This paper reports the status and details of the costs of construction of niobium superconducting resonant cavities for a linear accelerator, presently being built as a booster for the 15 UD tandem Pelletron accelerator at the Nuclear Science Centre, New Delhi. The linear accelerator will have three cryostat modules, each holding eight quarter-wave resonators. Construction of a batch of ten resonators for the linac started at Argonne National Laboratory in May 1997. For production, all fabrication and all electron beam welding is being done through commercial vendors. Details of construction and present status of the project are presented.
Date: March 16, 1999
Creator: Potukuchi, P. N.
Object Type: Article
System: The UNT Digital Library
Role of interfacial dislocations on creep of a fully lamellar tial (open access)

Role of interfacial dislocations on creep of a fully lamellar tial

Deformation mechanisms of a fully lamellar TiAl ({gamma} lamellae: 100 {approximately} 300 nm thick, {alpha}{sub 2} lamellae: 10 {approximately} 50 nm thick) crept at 760 C have been investigated. It was found that, as a result of a fine structure, the motion and multiplication of dislocations within both {gamma} and {alpha}{sub 2} lamellae are limited at low creep stresses (< 400 MPa). Thus, the glide and climb of lattice dislocations have insignificant contribution to creep deformation. In contrast, the motion of interfacial dislocations on {gamma}{alpha}{sub 2} and {gamma}{gamma} interfaces (i.e. interface sliding) dominates the deformation at low stresses. The major obstacles impeding the motion of interfacial dislocations was found to be lattice dislocations impinging on lamellar interfaces. The number of impinging lattice dislocations increases as the applied stress increases and, subsequently, causes the pileup of interfacial dislocations on the interfaces. The pileup further leads to the formation of deformation twins. Deformation twinning activated by the pileup of interfacial dislocations is suggested to be the dominant deformation mechanism at high stresses (> 400 MPa).
Date: August 16, 1999
Creator: Hsiung, L M & Nieh, T G
Object Type: Article
System: The UNT Digital Library
Transporting transuranic waste to the Waste Isolation Pilot Plant: Risk and cost perspectives (open access)

Transporting transuranic waste to the Waste Isolation Pilot Plant: Risk and cost perspectives

The Waste Isolation Pilot Plant (WIPP) is an authorized US Department of Energy (DOE) research and development facility constructed near the city of Carlsbad in southeastern New Mexico. The facility is intended to demonstrate the safe disposal of transuranic (TRU) radioactive waste resulting from US defense activities. Under the WIPP Land Withdrawal Act of 1992 (LWA), federal lands surrounding the WIPP facility were withdrawn from all public use and the title of those lands was transferred to the Secretary of Energy. The DOE's TRU waste is stored, and in some cases is still being generated, at 10 large-quantity and 13 small-quantity sites across the US. After applicable certification requirements have been met, the TRU waste at these sites will be sent to the WIPP to initiate the disposal phase of the facility, which according to current planning is projected to last for approximately 35 years.
Date: February 16, 1999
Creator: Biwer, B. M.; Gilette, J. L.; Poch, L. A. & Suermann, J. F.
Object Type: Article
System: The UNT Digital Library
Gas Release During Saltwell Pumping: Interpretation of Operational Data (open access)

Gas Release During Saltwell Pumping: Interpretation of Operational Data

The Hanford Site has 149 single-shell tanks (SSTs) containing radioactive waste that is a complex mix of radioactive and chemical products. Of these, 67 are known or suspected to have leaked liquid into the surrounding soil, while 82 are considered sound (Hanlon 1999). To minimize the amount of material that potentially could leak into the surrounding soil, all of the SSTs are scheduled to have drainable liquid removed and to be designated as interim stabilized. Of the SSTs, 119 have been declared stabilized, and only 30 require further processing (Hanlon 1999). Many of the tanks have been declared stabilized administratively, with only 45 tanks having had drainable liquid removed. The pending consent decree between the Washington State Department of Ecology and the Office of River Protection. (U.S. District Court Eastern District of Washington, 1999) sets a milestone to complete interim stabilization by September 2004. While process equipment exists for removing drainable liquid, and its operation is well known from previous pumping campaigns, a number of safety issues associated with the release and potential ignition of flammable gases within the tanks needs to be addressed. The safety concerns associated with flammable gases stem from the observation that some of the waste …
Date: September 16, 1999
Creator: Huckaby, J. L.; Peurrung, L. M. & Gauglitz, P. A.
Object Type: Report
System: The UNT Digital Library
Intermediate Strain-Rate Loading Experiments - Technique and Applications to Ceramics (open access)

Intermediate Strain-Rate Loading Experiments - Technique and Applications to Ceramics

A new test methodology is described which allows access to loading rates that lie between split Hopkinson bar and shock-loading techniques. Gas gun experiments combined with velocity interferometry techniques have been used to experimentally determine the intermediate strain-rate loading behavior of Coors AD995 alumina and Cercom silicon-carbide rods. Graded-density materials have been used as impactors; thereby eliminating the tension states generated by the radial stress components during the loading phase. Results of these experiments demonstrate that the time-dependent stress pulse generated during impact allows an efficient transition from the initial uniaxial strain loading to a uniaxial stress state as the stress pulse propagates through the rod. This allows access to intermediate loading rates over 5 x 10{sup 3}/s to a few times 10{sup 4}/s.
Date: August 16, 1999
Creator: Chhabildas, L. C. & Reinhart, W. D.
Object Type: Article
System: The UNT Digital Library
Geochemical characterization of seaplane lagoon sediments, Alameda Naval Air Station (open access)

Geochemical characterization of seaplane lagoon sediments, Alameda Naval Air Station

Our objective in the characterization of sediments from Seaplane Lagoon at the Alameda Naval Air Station (NAS) was to determine the geochemical interactions that control the partitioning of cadmium, chromium, cobalt, copper, lead, mercury, nickel, and zinc between the sediments and the porewaters. Our approach was to collect several cores at the east outfall location of the Seaplane Lagoon. We determined the porewater chemistry by (1) making in situ micro-electrode measurements, (2) extracting porewaters, and (3) modeling geochemical reactions. We determined the sediment chemistry by measuring (1) elemental abundance, (2) mineralogy, and (3) trace-element speciation. This information should help the US Navy determine the long-term hazard of the sediments if they are left in place and the short-term hazard if they are dredged. We did not fully examine the geochemistry of sediments from the West Beach Landfill Wetlands site, because these sediments were distinct from the Seaplane Lagoon sediments. Our initial motivation for studying the Landfill Wetlands site was to determine the trace-element geochemistry in Seaplane Lagoon sediments that had been dredged and then disposed in the Landfill Wetlands. Unfortunately, the location of these dredged sediments is unknown. The cores we sampled were not from the Seaplane Lagoon.
Date: August 16, 1999
Creator: Bono, Andrew; Carroll, Susan; Esser, Brad; Luther, George W., III; O'Day, Peggy & Randall, Simon
Object Type: Report
System: The UNT Digital Library
Radiation Transport in Type IA Supernovae (open access)

Radiation Transport in Type IA Supernovae

It has been said more than once that the critical link between explosion models and observations is the ability to accurately simulate cooling and radiation transport in the expanding ejecta of Type Ia supernovae. It is perhaps frustrating to some of the theorists who study explosion mechanisms, and to some of the observers too, that more definitive conclusions have not been reached about the agreement, or lack thereof, between various Type Ia supernova models and the data. Although claims of superlative accuracy in transport simulations are sometimes made, I will argue here that there are outstanding issues of critical importance and in need of addressing before radiation transport calculations are accurate enough to discriminate between subtly different explosion models.
Date: November 16, 1999
Creator: Eastman, R
Object Type: Article
System: The UNT Digital Library
Surface topographic analyses of two-year coupons of alloy 22 from long-term corrosion testing (open access)

Surface topographic analyses of two-year coupons of alloy 22 from long-term corrosion testing

We have applied atomic force microscopy (AFM) to analyze the surface topographies associated with representatives of each of the classes of aqueous-baths from which coupons of Alloy 22 were exposed for two years in Long-Term Corrosion Testing. The data support the conclusion that the AFM offers little, if any qualitative information on the corrosion of coupons which are currently undergoing Long-Term Testing.
Date: December 16, 1999
Creator: Bedrossian, P J
Object Type: Report
System: The UNT Digital Library
Effects of Barometric Fluctuations on Well Water-Level Measurements and Aquifer Test Data (open access)

Effects of Barometric Fluctuations on Well Water-Level Measurements and Aquifer Test Data

This report examines the effects of barometric fluctuations on well water-level measurements and evaluates adjustment and removal methods for determining areal aquifer head conditions and aquifer test analysis. Two examples of Hanford Site unconfined aquifer tests are examined that demonstrate baro-metric response analysis and illustrate the predictive/removal capabilities of various methods for well water-level and aquifer total head values. Good predictive/removal characteristics were demonstrated with best corrective results provided by multiple-regression deconvolution methods.
Date: December 16, 1999
Creator: Spane, Frank A.
Object Type: Report
System: The UNT Digital Library
Gas Release During Saltwell Pumping: Interpretation of Operational Data (open access)

Gas Release During Saltwell Pumping: Interpretation of Operational Data

Gas Release During Saltwell Pumping: Interpretation of Operational Data
Date: September 16, 1999
Creator: Huckaby, James L.; Peurrung, Loni M. & Gauglitz, Phillip A.
Object Type: Report
System: The UNT Digital Library
Transverse Phase Space Reconstruction of the RHIC Beam (open access)

Transverse Phase Space Reconstruction of the RHIC Beam

None
Date: February 16, 1999
Creator: Connolly, R.
Object Type: Report
System: The UNT Digital Library