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Nuclear fusion driven by coulomb explosions of deuterium clusters (open access)

Nuclear fusion driven by coulomb explosions of deuterium clusters

We have examined the interaction of deuterium clusters with high intensity, ultrafast laser radiation. Upon irradiation a hot plasma is created with a sufficient temperature to produce nuclear fusion. We have seen that larger clusters produce more fusion neutrons than smaller clusters, consistent with a Coulomb explosion model. Fusion yield is currently limited by propagation effects. Using inter ferometric imaging we have examined the laser propagation and found that the laser energy is absorbed before it penetrates to the center (highest density region) of the gas jet.
Date: June 9, 2000
Creator: Zweiback, J.; Smith, R. A.; Cowan, T. E.; Hays, G.; Hartley, J.; Howell, R. et al.
System: The UNT Digital Library
Transition From in-Plane to Out-of-Plane Azimuthal Enhancement in Au+Au Collisions (open access)

Transition From in-Plane to Out-of-Plane Azimuthal Enhancement in Au+Au Collisions

The incident energy at which the azimuthal distributions in semi-central heavy ion collisions change from in-plane to out-of-plane enhancement--E{sub tran} is studied as a function of mass of emitted particles, their transverse momentum and centrality for Au+Au collisions. The analysis is performed in a reference frame rotated with the sidewards flow angle ({Theta}{sub flow}) relative to the beam axis. A systematic decrease of E{sub tran} as function of mass of the reaction products, their transverse momentum and collision centrality is evidenced. The predictions of a microscopic transport model (IQMD) are compared with the experimental results.
Date: August 9, 2000
Creator: Andronic, A.; Stoicea, G.; Petrovici, M.; Simion, V.; Crochet, P.; Alard, J. P. et al.
System: The UNT Digital Library
A possible hadronic excess in psi(2S) decay and the rho pi puzzle (open access)

A possible hadronic excess in psi(2S) decay and the rho pi puzzle

We study the so-called {rho}{pi} puzzle of the {psi}(2S) decay by incorporating two inputs; the relative phase between the one-photon and the gluonic decay amplitude, and a possible hadronic excess in the inclusive nonelectromagnetic decay rate of {psi}(2S). We look into the possibility that the hadronic excess in {psi}(2S) originates from a decay process of long-distance origin which is absent from the J/{upsilon} decay. We propose that the amplitude of this additional process happens to nearly cancel the short-distance gluonic amplitude in the exclusive decay {psi}(2S) {yields} 1{sup -}0{sup -} and turn the sum dominantly real in contrast to the J/{psi} decay. We present general consequences of this mechanism and survey two models which might possibly explain the source of this additional amplitude.
Date: November 9, 2000
Creator: Suzuki, Mahiko
System: The UNT Digital Library
Extreme Ultraviolet Lithography - Reflective Mask Technology (open access)

Extreme Ultraviolet Lithography - Reflective Mask Technology

EUVL mask blanks consist of a distributed Bragg reflector made of 6.7nm-pitch bi-layers of MO and Si deposited upon a precision Si or glass substrate. The layer deposition process has been optimized for low defects, by application of a vendor-supplied but highly modified ion-beam sputter deposition system. This system is fully automated using SMIF technology to obtain the lowest possible environmental- and handling-added defect levels. Originally designed to coat 150mm substrates, it was upgraded in July, 1999 to 200 mm and has coated runs of over 50 substrates at a time with median added defects >100nm below 0.05/cm{sup 2}. These improvements have resulted from a number of ion-beam sputter deposition system modifications, upgrades, and operational changes, which will be discussed. Success in defect reduction is highly dependent upon defect detection, characterization, and cross-platform positional registration. We have made significant progress in adapting and extending commercial tools to this purpose, and have identified the surface scanner detection limits for different defect classes, and the signatures of false counts and non-printable scattering anomalies on the mask blank. We will present key results and how they have helped reduce added defects. The physics of defect reduction and mitigation is being investigated by a …
Date: May 9, 2000
Creator: Walton, C. C.; Kearney, P. A.; Mirkarimi, P. B.; Bowers, J. M.; Cerjan, C.; Warrick, A. L. et al.
System: The UNT Digital Library
Pursuing the origin of electroweak symmetry breaking: a 'Bayesian Physics' argument for sqrt(s) <~; 600 GeV e+e- collider (open access)

Pursuing the origin of electroweak symmetry breaking: a 'Bayesian Physics' argument for sqrt(s) <~; 600 GeV e+e- collider

High-energy data has been accumulating over the last ten years, and it should not be ignored when making decisions about the future experimental program. In particular, we argue that the electroweak data collected at LEP, SLC and Tevatron indicate a light scalar particle with mass less than 500 GeV. This result is based on considering a wide variety of theories including the Standard Model, supersymmetry, large extra dimensions, and composite models. We argue that a high luminosity, 600 GeV e{sup +}e{sup -} collider would then be the natural choice to feel confident about finding and studying states connected to electroweak symmetry breaking. We also argue from the data that worrying about resonances at multi-TeV energies as the only signal for electroweak symmetry breaking is not as important a discovery issue for the next generation of colliders. Such concerns should perhaps be replaced with more relevant discovery issues such as a Higgs boson that decays invisibly, and ''new physics'' that could conspire with a heavier Higgs boson to accommodate precision electroweak data. An e{sup +}e{sup -} collider with {radical}s {approx}&lt; 600 GeV is ideally suited to cover these possibilities.
Date: August 9, 2000
Creator: Kane, G.L. & Wells, James D.
System: The UNT Digital Library
Component Technology for High-Performance Scientific Simulation Software (open access)

Component Technology for High-Performance Scientific Simulation Software

We are developing scientific software component technology to manage the complexity of modem, parallel simulation software and increase the interoperability and re-use of scientific software packages. In this paper, we describe a language interoperability tool named Babel that enables the creation and distribution of language-independent software libraries using interface definition language (IDL) techniques. We have created a scientific IDL that focuses on the unique interface description needs of scientific codes, such as complex numbers, dense multidimensional arrays, complicated data types, and parallelism. Preliminary results indicate that in addition to language interoperability, this approach provides useful tools for thinking about the design of modem object-oriented scientific software libraries. Finally, we also describe a web-based component repository called Alexandria that facilitates the distribution, documentation, and re-use of scientific components and libraries.
Date: November 9, 2000
Creator: Epperly, T; Kohn, S & Kumfert, G
System: The UNT Digital Library
Comparison of imaging spectrometers (open access)

Comparison of imaging spectrometers

Realistic signal to noise performance estimates for the various types of instruments being considered for NGST are compared, based on the point source detection values quoted in the available ISIM final reports. The corresponding sensitivity of the various types of spectrometers operating in a full field imaging mode, for both emission line objects and broad spectral distribution objects, is computed and displayed. For the purpose of seeing the earliest galaxies, or the faintest possible emission line sources, the imaging Fourier transform spectrometer emerges superior to all others, by orders of magnitude in speed.
Date: January 9, 2000
Creator: Bennett, C
System: The UNT Digital Library
X-Ray Absorption and Soft X-Ray Fluorescence Analysis of Kdp Optics (open access)

X-Ray Absorption and Soft X-Ray Fluorescence Analysis of Kdp Optics

Potassium Dihydrogen Phosphate (KDP) is a non-linear optical material used for laser frequency conversion and optical switches. Unfortunately, when KDP crystals are coated with a porous silica anti-reflection coating [1] and then exposed to ambient humidity, they develop dissolution pits [2,3]. Previous investigations [2] have shown that thermal annealing renders KDP optics less susceptible to pitting suggesting that a modification of surface chemistry has occurred. X-ray absorption and fluorescence were used to characterize changes in the composition and structure of KDP optics as a function of process parameters. KDP native crystals were also analyzed to provide a standard basis for interpretation. Surface sensitive total electron yield and bulk sensitive fluorescence yield from the K 2p, P 2p (L{sub 2,3}-edge) and O 1s (K-edge) absorption edges were measured at each process step. Soft X-ray fluorescence was also used to observe changes associated with spectral differences noted in the absorption measurements. Results indicate that annealing at 160 C dehydrates the surface of KDP resulting in a metaphosphate surface composition with K:P:O = 1:1:3.
Date: August 9, 2000
Creator: Nelson, A. J.; van Buuren, T.; Miller, E.; Land, T. A.; Bostedt, C.; Franco, N. et al.
System: The UNT Digital Library
Experimental Testbed for the Study of Hydrodynamic Issues in Supernovae (open access)

Experimental Testbed for the Study of Hydrodynamic Issues in Supernovae

More than a decade after the explosion of SN 1987A, unresolved discrepancies still remain in attempts to numerically simulate the mixing processes initiated by the passage of a very strong shock through the layered structure of the progenitor star. Numerically computed velocities of the radioactive {sup 56}Ni and {sup 56}CO, produced by shock-induced explosive burning within the silicon layer for example, are still more than 50% too low as compared with the measured velocities. In order to resolve such discrepancies between observation and simulation, an experimental testbed has been designed on the Omega Laser for the study of hydrodynamic issues of importance to supernovae (SNe). In this paper, we present results from a series of scaled laboratory experiments designed to isolate and explore several issues in the hydrodynamics of SN explosions. The results of the experiments are compared with numerical simulations and are generally found to be in reasonable agreement.
Date: October 9, 2000
Creator: Robey, H. F.; Kane, J. O.; Remington, B. A.; Drake, R. P.; Hurricane, O. A.; Louis, H. et al.
System: The UNT Digital Library
Gas Phase Chemical Detection with an Integrated Chemical Analysis System (open access)

Gas Phase Chemical Detection with an Integrated Chemical Analysis System

None
Date: October 9, 2000
Creator: Casalnuovo, S. A.; Frye-Mason, G. C.; Kottenstette, R.; Heller, E. J.; Matzke, C. M.; Lewis, P. R. et al.
System: The UNT Digital Library
New 500-kV Ion Source Test Strand for HIF (open access)

New 500-kV Ion Source Test Strand for HIF

One of the most challenging aspects of ion beam driven inertial fusion energy is the reliable and efficient generation of low emittance, high current ion beams. The primary ion source requirements include a rise time of order 1-{micro}sec, a pulse width of at least 20-{micro}sec, a flattop ripple of less than 0.1% and a repetition rate of at least 5-HZ. Naturally, at such a repetition rate, the duty cycle of the source must be greater than 10{sup 8} pulses. Although these specifications do not appear to exceed the state-of-the-art for pulsed power, considerable effort remains to develop a suitable high current ion source. Therefore, we are constructing a 500-kV test stand specifically for studying various ion source concepts including surface, plasma and metal vapor arc. This paper will describe the test stand design specifications as well as the details of the various subsystems and components.
Date: March 9, 2000
Creator: Sangster, T. C.; Ahle, L. E.; Halaxa, E. F.; Karpenko, V. P.; Oldaker, M. E.; Mitchell, J. W. et al.
System: The UNT Digital Library
[Printout of Dallas Voice article: Houston appeals court rules sodomy statute violates state's constitution] (open access)

[Printout of Dallas Voice article: Houston appeals court rules sodomy statute violates state's constitution]

Printout of Dallas Voice article concerning the Houston appeals court ruling that sodomy statute violates the Texas state constitution.
Date: June 9, 2000
Creator: unknown
System: The UNT Digital Library
Model Validation Studies of 459 Epoxy (open access)

Model Validation Studies of 459 Epoxy

None
Date: August 9, 2000
Creator: Morgan, Sarah A. & Stavig, Mark E.
System: The UNT Digital Library
Extending purchasing with document management, workflow and the internet (open access)

Extending purchasing with document management, workflow and the internet

Sandia is a national security laboratory operated for the U.S. department of Energy by the Sandia Corporation, a Lockheed Martin Company. Sandia designs all non-nuclear components for the nation's nuclear weapons, performs a wide variety of energy research and development projects, and works on assignments that respond to national security threats - both military and economic. They encourage and seek partnerships with appropriate U.S. industry and government groups to collaborate on emerging technologies that support their mission. Today, Sandia has two primary facilities, one in Albuquerque, New Mexico, and one in Livermore, California. They employ about 7,600 people and manage about $1.4 billion of work per year. In 1995, a decision was made to move from their in-house developed systems to commercial software. This decision was driven partly by Y2K compliance issues associated with the existing operating system and support environment. Peoplesoft was selected for human resources and Oracle for manufacturing and financial. They implemented Peoplesoft for human resources (HR) in 1997. They then implemented 7 Oracle modules in manufacturing in October 1998, including WIP, BOM, engineering, quality, inventory, MRP, cost management and limited HR/purchasing/receiving functionality required to support manufacturing. In March of 1999, they brought a portion of their …
Date: February 9, 2000
Creator: SIMPSON,SUZANNE L. & PERICH,JULIE K.
System: The UNT Digital Library
Computational fluid dynamics simulations of a glass melting furnace (open access)

Computational fluid dynamics simulations of a glass melting furnace

The glass production industry is one of the major users of natural gas in the US, and approximately 75% of the energy produced from natural gas is used in the melting process. Industrial scale glass melting furnaces are large devices, typically 5 or more meters wide, and twice as long. To achieve efficient heat transfer to the glass melt below, the natural gas flame must extend over a large portion of the glass melt. Therefore modern high efficiency burners are not used in these furnaces. The natural gas is injected as a jet, and a jet flame forms in the flow of air entering the furnace. In most current glass furnaces the energy required to melt the batch feed stock is about twice the theoretical requirement. An improved understanding of the heat transfer and two phase flow processes in the glass melt and solid batch mix offers a substantial opportunity for energy savings and consequent emission reductions. The batch coverage form and the heat flux distribution have a strong influence on the glass flow pattern. This flow pattern determines to a significant extent the melting rate and the quality of glass.
Date: May 9, 2000
Creator: Egelja, A. & Lottes, S. A.
System: The UNT Digital Library
A practical implementation of BICS for safety-critical applications (open access)

A practical implementation of BICS for safety-critical applications

This paper presents the challenges and solutions of applying Built-In-Current Sensors (BICS) to a safety-critical IC design for the purpose of in-situ state-of-health monitoring. The developed Quiscent Current Monitor (QCM) system consists of multiple BISC and digital control logic. The QCM BICS can detect leakage current as low as 4 {micro}A, run at system speed, and has relatively low real estate overhead. The QCM digital logic incorporates extensive debug capability and Built-In-Self-Test (BIST). The authors performed analog and digital simulations of the integrated BICS, and performed layout and tapeout of the design. Silicon is now in fabrication. Results to date show that, for some systems, BICS can be a practical and relatively inexpensive method for providing state-of-health monitoring of safety-critical microelectronics.
Date: February 9, 2000
Creator: SMITH,PATRICIA A. & CAMPBELL,DAVID V.
System: The UNT Digital Library
Evaluation of methods for estimating the uncertainty of electronic balance measurements (open access)

Evaluation of methods for estimating the uncertainty of electronic balance measurements

International and national regulations are requiring testing and calibration laboratories to provide estimates of uncertainty with their measurements. Many balance users are having questions about determining weight measurement uncertainty, especially if their quality control programs have provided estimates of measurement system ``bias and precision''. Part of the problem is the terminology used to describe the quality of weight and mass measurements. Manufacturer's specifications list several performance criteria, but do not provide estimates of the ``uncertainty'' of measurements made using an electronic balance. Several methods for estimating the uncertainty of weight and mass measurements have been described in various publications and regulations in recent years. This paper will discuss the terminology used to describe measurement quality, i.e. accuracy, precision, linearity, hysteresis, measurement uncertainty (MU) and the various contributors to MU and will discuss the advantages and limitations of various methods for estimating MU.
Date: June 9, 2000
Creator: Clark, J.P.
System: The UNT Digital Library
Current status and future prospects for the PVMaT project (open access)

Current status and future prospects for the PVMaT project

The goals of the Photovoltaic Manufacturing Technology project (PVMaT) are to help the US PV industry improve photovoltaic manufacturing processes and equipment; accelerate manufacturing cost reductions for PV modules, balance-of-systems components, and integrated systems; increase commercial product performance and reliability; and enhance the investment opportunities for substantial scale-ups of US-based PV manufacturing plant capacities. PVMaT is in its ninth year of implementation, and subcontracts have been completed from four solicitations for R and D on manufacturing process problems. They are in the second year of subcontracts for a fifth PVMaT solicitation. Based on the latest (1998) data from ten PVMaT industrial participants, the average direct manufacturing cost for these producers has been reduced by 29%--from $4.08 to $2.91 per peak watt since 1992--and there has also been a more than five-fold increase in manufacturing capacity-from 13.1 to 73.3 megawatts. The authors believe that continuing R and D on manufacturing processes contributes significantly to expeditious reductions in PV manufacturing costs, and they identify areas for future R and D.
Date: February 9, 2000
Creator: Witt, C. E.; Mitchell, R. L.; Symko-Davies, M.; Thomas, H. P.; King, R. & Ruby, D. S.
System: The UNT Digital Library
Calculation of Hamaker constants in non-aqueous fluid media (open access)

Calculation of Hamaker constants in non-aqueous fluid media

Calculations of the Hamaker constants representing the van der Waals interactions between conductor, resistor and dielectric materials are performed using Lifshitz theory. The calculation of the parameters for the Ninham-Parsegian relationship for several non-aqueous liquids has been derived based on literature dielectric data. Discussion of the role of van der Waals forces in the dispersion of particles is given for understanding paste formulation. Experimental measurements of viscosity are presented to show the role of dispersant truncation of attractive van der Waals forces.
Date: May 9, 2000
Creator: BELL,NELSON S. & DIMOS,DUANE B.
System: The UNT Digital Library
MEMS Reliability in Shock Environments (open access)

MEMS Reliability in Shock Environments

In order to determine the susceptibility of the MEMS (MicroElectroMechanical Systems) devices to shock, tests were performed using haversine shock pulses with widths of 1 to 0.2 ms in the range from 500g to 40,000g. The authors chose a surface-micromachined microengine because it has all the components needed for evaluation: springs that flex, gears that are anchored, and clamps and spring stops to maintain alignment. The microengines, which were unpowered for the tests, performed quite well at most shock levels with a majority functioning after the impact. Debris from the die edges moved at levels greater than 4,000g causing shorts in the actuators and posing reliability concerns. The coupling agent used to prevent stiction in the MEMS release weakened the die-attach bond, which produced failures at 10,000g and above. At 20,000g the authors began to observe structural damage in some of the thin flexures and 2.5-micron diameter pin joints. The authors observed electrical failures caused by the movement of debris. Additionally, they observed a new failure mode where stationary comb fingers contact the ground plane resulting in electrical shorts. These new failure were observed in the control group indicating that they were not shock related.
Date: February 9, 2000
Creator: Tanner,Danelle M.; Walraven,Jeremy A.; Helgesen,Karen Sue; Irwin,Lloyd W.; Brown,Frederick A.; Smith,Norman F. et al.
System: The UNT Digital Library
TRACE GAS MEASUREMENTS IN PHOENIX, ARIZONA (1998). (open access)

TRACE GAS MEASUREMENTS IN PHOENIX, ARIZONA (1998).

The DOE Atmospheric Chemistry Program, and the Arizona Department of Environmental Quality (DEQ) conducted a field program in the Phoenix Metropolitan area in the late spring of 1998. The experiment was composed of a linked set of aircraft and surface measurements designed to characterize the chemical and meteorological processes leading to ozone episodes. The existing network of Arizona DEQ sites in Phoenix was utilized to document ground level concentrations of ozone and its precursors. West of the downtown area, a site (Usery Pass) was set up for the detailed characterization of the mature Phoenix urban plume. Detailed measurements in the source region were made at several sites in downtown Phoenix. The DOE G-1 aircraft, equipped with a comprehensive array of instruments to characterize atmospheric trace gas and aerosol composition, flew over the region at various times during the day. All times in the following discussion are local standard time (LST). Morning flights were typically made between 08:00 and 12:00 upwind, to measure background concentrations, and over the Phoenix source region, to characterize the sources of ozone precursors. Afternoon flights over the Phoenix source region and downwind between 15:00 and 18:00 were made to examine the chemical properties and physical distribution …
Date: January 9, 2000
Creator: NUNNERMACKER,L.J.
System: The UNT Digital Library
Application of a World Wide Web technology to environmental remediation (open access)

Application of a World Wide Web technology to environmental remediation

As part of the Formerly Utilized Site Remedial Action Program (FUSRAP), the United States Army Corps of Engineers (USACE), Buffalo District, is responsible for overseeing the remediation of several sites within its jurisdiction. FUSRAP sites are largely privately held facilities that were contaminated by activities associated with the nuclear weapons program in the 1940s, 50s, and 60s. The presence of soils and structures contaminated with low levels of radionuclides is a common problem at these sites. Typically, contaminated materials must be disposed of off-site at considerable expense (up to several hundred dollars per cubic yard of waste material). FUSRAP is on an aggressive schedule, with most sites scheduled for close-out in the next couple of years. Among the multitude of tasks involved in a typical remediation project is the need to inform and coordinate with active stakeholder communities, including local, state, and federal regulators.
Date: March 9, 2000
Creator: Johnson, R. & Durham, L. A.
System: The UNT Digital Library
Device characteristics of the PnP AlGaAs/InGaAsN/GaAs double heterojunction bipolar transistor (open access)

Device characteristics of the PnP AlGaAs/InGaAsN/GaAs double heterojunction bipolar transistor

The authors have demonstrated a functional PnP double heterojunction bipolar transistor (DHBT) using AlGaAs, InGaAsN, and GaAs. The band alignment between InGaAsN and GaAs has a large {triangle}E{sub C} and a negligible {triangle}E{sub V}, and this unique characteristic is very suitable for PnP DHBT applications. The metalorganic vapor phase epitaxy (MOCVD) grown Al{sub 0.3}Ga{sub 0.7}As/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01}/GaAs PnP DHBT is lattice matched to GaAs and has a peak current gain of 25. Because of the smaller bandgap (Eg = 1.20 eV) of In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} used for the base layer, this device has a low V{sub ON} of 0.79 V, which is 0.25 V lower than in a comparable Pnp AlGaAs/GaAs HBT. And because GaAs is used for the collector, its BV{sub CEO} is 12 V, consistent with BV{sub CEO} of AlGaAs/GaAs HBTs of comparable collector thickness and doping level.
Date: February 9, 2000
Creator: Chang, Ping-Chih; Li, N. Y.; Laroche, J. R.; Baca, Albert G.; Hou, H. Q. & Ren, F.
System: The UNT Digital Library
ISOcxx: The C++ portability package (open access)

ISOcxx: The C++ portability package

The level of C++ compliers' adherence to the ISO C++ standard varies considerably from compiler to compiler. This variability has significantly hindered users' attempts as standard-compliant C++ coding practices. ISOcxx is a software package that addresses such deficient aspects of users' C++ development environments. This portability package: (1) probes an environment to identify areas of non-compliance (defects) with the standard, and (2) supplies, where possible, compliance code so as to mitigate (cure) the ill effects of the detected defects. Each defect typically results from a feature that is required by the ISO C++ standard, but that a particular environment omits entirely, provides only incompletely, matches to an outdated draft of the standard, or otherwise incorrectly supports. A cure is applicable if test programs demonstrating the corresponding defect can be successfully compiled and run when the compliance code is incorporated. Where no compliance code is available, client code is nonetheless made aware of the defect and can thus avoid the offending construct. Thus, this package allows client code to be maximally compliant with the international C++ standard, yet still be acceptable to many otherwise-defective environments.
Date: February 9, 2000
Creator: Brown, W.E.
System: The UNT Digital Library