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B Decays as a probe of spontaneous cp-violation in SUSY models (open access)

B Decays as a probe of spontaneous cp-violation in SUSY models

We consider phenomenological implications of susy models with spontaneously broken CP-symmetry. In particular, we analyze CP-asymmetries in B decays and find that the predictions of these models are vastly different from those of the SM. These features are common to NMSSM-like models with an arbitrary number of sterile superfields and the MSSM with broken R-parity.
Date: July 8, 1999
Creator: Lebedev, Oleg
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

Microfabrication technology has been applied to the development of a miniature, multi-channel gas phase chemical laboratory that provides fast response, small size, and enhanced versatility and chemical discrimination. Each analysis channel includes a sample concentrator followed by a gas chromatographic separator and a chemically selective surface acoustic wave detector array to achieve high sensitivity and selectivity. The performance of the components, individually and collectively, is described. The design and performance of novel micromachined acoustic wave devices, with the potential for improved chemical sensitivity, are also described.
Date: July 8, 1999
Creator: Baca, Albert G.; Casalnuovo, Stephen A.; Frye-Mason, Gregory C.; Heller, Edwin J.; Hietala, Susan L.; Hietala, Vincent M. et al.
System: The UNT Digital Library
RF and mm-Wave Photonics at Sandia National Laboratories (open access)

RF and mm-Wave Photonics at Sandia National Laboratories

RF and mm-wave photonic devices and circuits have been developed at Sandia National Laboratories for applications ranging from RF optical data links to optical generation of mm-wave frequencies. This talk will explore recent high-speed photonics technology developments at Sandia including: (1) A monolithic optical integrated circuit for all-optical generation of mm-waves. Using integrated mode-locked diode lasers, amplifiers, and detectors, frequencies between 30 GHz and 90 GHz are generated by a single monolithic (Al,Ga)As optical circuit less than 2mm in its largest dimension. (2) Development of polarization-maintaining, low-insertion-loss, low v-pi, Mach-Zehnder interferometer (MZI) modulators with DC-to-potentially-K-band modulation bandwidth. New low-loss polarization-maintaining waveguide designs using binary alloys have been shown to reduce polarization crosstalk in undoped (Al,Ga)As waveguides, yielding high extinction ratio (>40dB) and low on-chip loss (<6dB) in Mach-Zehnder interferometers. RF drive voltage is reduced through use of 45rnrn-active length devices with modulator sensitivity, v-pi, less than 3V.
Date: July 8, 1999
Creator: Vawter, G. A. & Sullivan, C.
System: The UNT Digital Library
High-resolution wavefront control of high-power laser systems (open access)

High-resolution wavefront control of high-power laser systems

Nearly every new large-scale laser system application at LLNL has requirements for beam control which exceed the current level of available technology. For applications such as inertial confinement fusion, laser isotope separation, laser machining, and laser the ability to transport significant power to a target while maintaining good beam quality is critical. There are many ways that laser wavefront quality can be degraded. Thermal effects due to the interaction of high-power laser or pump light with the internal optical components or with the ambient gas are common causes of wavefront degradation. For many years, adaptive optics based on thing deformable glass mirrors with piezoelectric or electrostrictive actuators have be used to remove the low-order wavefront errors from high-power laser systems. These adaptive optics systems have successfully improved laser beam quality, but have also generally revealed additional high-spatial-frequency errors, both because the low-order errors have been reduced and because deformable mirrors have often introduced some high-spatial-frequency components due to manufacturing errors. Many current and emerging laser applications fall into the high-resolution category where there is an increased need for the correction of high spatial frequency aberrations which requires correctors with thousands of degrees of freedom. The largest Deformable Mirrors currently available …
Date: July 8, 1999
Creator: Brase, J.; Brown, C.; Carrano, C.; Kartz, M.; Olivier, S.; Pennington, D. et al.
System: The UNT Digital Library
Unattended Monitoring System Design Methodology (open access)

Unattended Monitoring System Design Methodology

A methodology for designing Unattended Monitoring Systems starting at a systems level has been developed at Sandia National Laboratories. This proven methodology provides a template that describes the process for selecting and applying appropriate technologies to meet unattended system requirements, as well as providing a framework for development of both training courses and workshops associated with unattended monitoring. The design and implementation of unattended monitoring systems is generally intended to respond to some form of policy based requirements resulting from international agreements or domestic regulations. Once the monitoring requirements are established, a review of the associated process and its related facilities enables identification of strategic monitoring locations and development of a conceptual system design. The detailed design effort results in the definition of detection components as well as the supporting communications network and data management scheme. The data analyses then enables a coherent display of the knowledge generated during the monitoring effort. The resultant knowledge is then compared to the original system objectives to ensure that the design adequately addresses the fundamental principles stated in the policy agreements. Implementation of this design methodology will ensure that comprehensive unattended monitoring system designs provide appropriate answers to those critical questions imposed by …
Date: July 8, 1999
Creator: Drayer, D. D.; DeLand, S. M.; Harmon, C. D.; Matter, J. C.; Martinez, R. L. & Smith, J. D.
System: The UNT Digital Library
Experiences Using a Meta-Data Based Integration Infrastructure (open access)

Experiences Using a Meta-Data Based Integration Infrastructure

A data warehouse that presents data from many of the genomics community data sources in a consistent, intuitive fashion has long been a goal of bioinformatics. Unfortunately, it is one of the goals that has not yet been achieved. One of the major problems encountered by previous attempts has been the high cost of creating and maintaining a warehouse in a dynamic environment. In this abstract we have outlined a meta-data based approach to integrating data sources that begins to address this problem. We have used this infrastructure to successfully integrate new sources into an existing warehouse in substantially less time than would have traditionally been required--and the resulting mediators are more maintainable than the traditionally defined ones would have been. In the final paper, we will describe in greater detail both our architecture and our experiences using this framework. In particular, we will outline the new, XML based representation of the meta-data, describe how the mediator generator works, and highlight other potential uses for the meta-data.
Date: July 8, 1999
Creator: Critchlow, T.; Masick, R. & Slezak, T.
System: The UNT Digital Library
Optical Readout of Micro-Accelerometer Code Features (open access)

Optical Readout of Micro-Accelerometer Code Features

Micromachine accelerometers offer a way to enable critical functions only when a system encounters a particular acceleration environment. This paper describes the optical readout of a surface micromachine accelerometer containing a unique 24-bit code. The readout uses waveguide-based optics, which are implemented as a photonic integrated circuit (PIC). The PIC is flip-chip bonded over the micromachine, for a compact package. The shuttle moves 500 {micro}m during readout, and each code element is 17 {micro}m wide. The particular readout scheme makes use of backscattered radiation from etched features in the accelerometer shuttle. The features are etched to create corner reflectors that return radiation back toward the source for a one bit. For a zero bit, the shuttle is not etched, and the radiation scatters forward, away from the detector. This arrangement provides a large signal difference between a one and zero signal, since the zero signal returns virtually no signal to the detector. It is thus superior to schemes that interrogate the code vertically, which have a limited contrast between a one and a zero. Experimental results are presented for mock shuttle features etched into a silicon substrate. To simulate the shuttle moving under a fixed PIC, a commercially available waveguide …
Date: July 8, 1999
Creator: Dickey, Fred M.; Holswade, Scott C.; Polosky, Marc A.; Shagam, Richard N. & Sullivan, Charles T.
System: The UNT Digital Library
3-D Silicon Photonic Lattices- Cornerstone of an Emerging Photonics Revolution (open access)

3-D Silicon Photonic Lattices- Cornerstone of an Emerging Photonics Revolution

Three-dimensional photonic lattices are engineered materials which are the photonic analogues of semiconductors. These structures were first proposed and demonstrated in the mid-to-late 1980's. However, due to fabrication difficulties, lattices active in the infrared are only just emerging. Wide ranges of structures and fabrication approaches have been investigated. The most promising approach for many potential applications is a diamond-like structure fabricated using silicon microprocessing techniques. This approach has enabled the fabrication of 3-D silicon photonic lattices active in the infrared. The structures display band gaps centered from 12{micro} down to 1.55{micro}.
Date: July 8, 1999
Creator: Fleming, J.G. & Lin, Shawn-Yu
System: The UNT Digital Library
Application of the Two-Parameter J-A2 Description to Ductile Crack Growth (open access)

Application of the Two-Parameter J-A2 Description to Ductile Crack Growth

Typical ASTM fracture testing determines J-integral resistance (J-R) curve or fracture toughness (JIC) based on specimens with high constraint geometry such as those specified in ASTM E1737-96. A three-term asymptotic solution with two parameters J and A2 (a constraint parameter) has been developed for characterizing the constraint effect of various geometries. The present paper extends the J-A2 characterization of a stationary crack tip to the regime of stable crack growth. Similar to the concept of J-controlled crack growth, the J-A2 description can be approximately used to characterize ductile crack growth under certain amount of crack extension. The region of J-A2 controlled crack growth is much larger than that controlled by J-integral alone. From the relationships between A2 and the test data, JIC and tearing modulus (TR), the coefficients used to define a J-R curve can be determined. For non-standard specimens or actual structures, once the constraint parameter A2 is determined, the J-R curves appropriate for these geometries can then be obtained. A procedure of transferring J-R curves determined from the standard ASTM procedure to non-standard specimens or flawed structures is outlined in the paper.
Date: July 8, 1999
Creator: Lam, P.S.
System: The UNT Digital Library
The Potential for Low-Cost Concentrating Solar Power Systems (open access)

The Potential for Low-Cost Concentrating Solar Power Systems

Concern over the possibility of global climate change as a result of anthropogenic greenhouse gas buildup in the atmosphere is resulting in increased interest in renewable energy technologies. The World Bank recently sponsored a study to determine whether solar thermal power plants can achieve cost parity with conventional power plants. The paper reviews the conclusions of that study.
Date: July 8, 1999
Creator: Price, H. W. (National Renewable Energy Laboratory) & Carpenter, S. (Enermodal Engineering Limited)
System: The UNT Digital Library
Self-Adjoint Angular Flux Equation for Coupled Electron-Photon Transport (open access)

Self-Adjoint Angular Flux Equation for Coupled Electron-Photon Transport

Recently, Morel and McGhee described an alternate second-order form of the transport equation called the self adjoint angular flux (SAAF) equation that has the angular flux as its unknown. The SAAF formulation has all the advantages of the traditional even- and odd-parity self-adjoint equations, with the added advantages that it yields the full angular flux when it is numerically solved, it is significantly easier to implement reflective and reflective-like boundary conditions, and in the appropriate form it can be solved in void regions. The SAAF equation has the disadvantage that the angular domain is the full unit sphere and, like the even- and odd- parity form, S{sub n} source iteration cannot be implemented using the standard sweeping algorithm. Also, problems arise in pure scattering media. Morel and McGhee demonstrated the efficacy of the SAAF formulation for neutral particle transport. Here we apply the SAAF formulation to coupled electron-photon transport problems using multigroup cross-sections from the CEPXS code and S{sub n} discretization.
Date: July 8, 1999
Creator: Liscum-Powell, J. L.; Lorence, L. J., Jr.; Morel, J. E. & Prinja, A. K.
System: The UNT Digital Library
Refractive Index and Hygroscopic Stability of Al(x)Ga(1-x)As Native Oxides (open access)

Refractive Index and Hygroscopic Stability of Al(x)Ga(1-x)As Native Oxides

The authors present prism coupling measurements on Al{sub x}Ga{sub 1{minus}x}As native oxides showing the dependence of refractive index on composition (0.3 {le} x {le} 0.97), oxidation temperature (400 {le} T {le} 500), and carrier gas purity. Index values range from n = 1.490 (x = 0.9, 400) to 1.707 (x = 0.3, 500 C). The oxides are shown to adsorb moisture, increasing their index by up to 0.10 (7%). Native oxides of Al{sub x}Ga{sub 1{minus}x}As (x {le} 0.5) have index values up to 0.27 higher and are less hygroscopic when prepared with a small amount of O{sub 2} in the N{sub 2} + H{sub 2}O process gas. The higher index values are attributed to a greater degree of oxidation of the Ga in the film.
Date: July 8, 1999
Creator: Blum, O.; Epstein, R. J.; Hou, H.; Hall, D. C.; Kou, L.; Luo, Y. et al.
System: The UNT Digital Library
Progress and future plans for MPC and A at Chelyabinsk-70 (open access)

Progress and future plans for MPC and A at Chelyabinsk-70

This paper describes that portion of the Nuclear Materials Protection, Control, and Accounting (MPC and A) program that is directed specifically to the needs of the All Russian Scientific Research Institute of Technical Physics (VNIITF), also called Chelyabinsk-70. Chelyabinsk-70 is located in the Ural Mountains, approximately 2000 km east of Moscow and 100 km south of Ekaterinburg. The MPC and A work that has been completed, is underway and planned at the facility will be described. During the first two years of the VNIITF project, emphasis was on the Pulse Research Reactor Facility (PRR), which contains one metal and two liquid pulse reactors and associated nuclear material storage rooms and a control center. A commissioning of the PRR was held in May of 1998. With the completion of the MPC and A work in the PRR, new physical protection work is focusing on other areas. VNIITF-wide physical protection initiatives underway include access control and computerized badging systems, and a central MPC and A control system. Measured physical inventory taking is a high priority for the VNIITF Project Team. A VNIITF-wide computerized accounting system is also being developed for the large and diverse inventory of nuclear material subject to MPC and …
Date: July 8, 1999
Creator: Apt, K.; Blasy, J.; Bukin, D.; Cahalane, P.; Churikov, Y.; Curtis, D. et al.
System: The UNT Digital Library
Progress toward hydrogen peroxide micropulsion (open access)

Progress toward hydrogen peroxide micropulsion

A new self-pressurizing propulsion system has liquid thrusters and gas jet attitude control without heavy gas storage vessels. A pump boosts the pressure of a small fraction of the hydrogen peroxide, so that reacted propellant can controllably pressurize its own source tank. The warm decomposition gas also powers the pump and is supplied to the attitude control jets. The system has been incorporated into a prototype microsatellite for terrestrial maneuvering tests. Additional progress includes preliminary testing of a bipropellant thruster, and storage of unstabilized hydrogen peroxide in small sealed tanks.
Date: July 8, 1999
Creator: Whitehead, J. C.; Dittman, M. D. & Ledebuhr, A. G.
System: The UNT Digital Library
W-Coating for MEMS (open access)

W-Coating for MEMS

The integration of miniaturized mechanical components has spawned a new technology known as microelectromechanical systems (MEMS). Surface micromachining, defined as the fabrication of micromechanical structures from deposited thin films, is one of the core technological processes underlying MEMS. Surface micromachined structures have a large ratio of surface area to volume which makes them particularly vulnerable to adhesion to the substrate or adjacent structures during release or in use--a problem is called stiction. Since microactuators can have surfaces in normal or sliding contact, function and wear are critical issues for reliable operation of MEMS devices. Surface modifications are needed to reduce adhesion and friction in micromechanical structures. In this paper, we will present a process used to selectively coat MEMS devices with Tungsten using a CVD (Chemical Vapor Deposition) process. We will discuss the effect of wet and vapor phase cleans along with different process variables. Endurance of the W coating is important, especially in applications where wear due to repetitive contacts with the film may occur. Further, tungsten is hard and chemically inert, Tungsten CVD is used in the integrated-circuit industry, which makes this, approach manufacturable.
Date: July 8, 1999
Creator: Fleming, J. G.; Mani, S. S. & Sniegowski, J. J.
System: The UNT Digital Library
Design and Analysis of a Micro-Optical Position Readout for Acceleration Sensing (open access)

Design and Analysis of a Micro-Optical Position Readout for Acceleration Sensing

Sandia National Laboratories is developing a MEMS-based trajectory safety subsystem, which allows enablement of critical functions only after a particular acceleration environment has been achieved. The device, known as an Environmental Sensing Device (ESD), consists of a suspended moving shuttle that translates a given distance when exposed to an appropriate acceleration environment. The shuttle contains an embedded code, consisting of grating structures, that is illuminated and optically read using a semiconductor laser and detector integrated together in a GaAs-based Photonic Integrated Circuit (PIC) flip-chip bonded to the assembly. This paper will describe the optical design and performance analysis of the embedded code features in the shuttle.
Date: July 8, 1999
Creator: Dickey, Fred M.; Holswade, Scott C. & Shagam, Richard N.
System: The UNT Digital Library
High-Aspect-Ratio Nanophotonic Components Fabricated by Cl(2) RIBE (open access)

High-Aspect-Ratio Nanophotonic Components Fabricated by Cl(2) RIBE

We describe highly anisotropic reactive ion beam etching of nanophotonic structures in AlGaAs based on the ion beam divergence angle and chamber pressure. The divergence angle is shown to influence the shape of the upper portion of the etch while the chamber pressure controls the shape of the lower portion. This predictable region of parameter space resulted in highly anisotropic nanostructures. Deeply etched distributed Bragg reflectors are etched to an aspect ratio of 8:1 with 100 nm trench widths. The profile of the grating etch is straight with smooth sidewalls, flat bottoms, and squared corners. Two-dimensional photonic crystal post arrays are fabricated with smooth and vertical sidewalls, with structures as small as 180 nm in diameter and 2.0 {micro}m in height.
Date: July 8, 1999
Creator: Zubrzycki, W. J.; Vawter, G. A. & Wendt, J. R.
System: The UNT Digital Library
Flight Performance of UV Filters on the ALEXIS Satellite (open access)

Flight Performance of UV Filters on the ALEXIS Satellite

The ALEXIS (Array of Low-Energy X-ray Imaging Sensors) mission, serving as the first dedicated all-sky monitor in the extreme UV, has been collecting data since its launch in 1993. ALEXIS operates in a 70{degree} inclination orbit at an altitude of 800 km. The ALEXIS science mission is to observe the cosmic UV background and to study variability of EUV sources. The ALEXIS experiment is composed of six telescopes. Although the telescopes were only designed for a one-year technology verification mission, they are still functioning with much the same effectiveness as at the beginning of the mission. The telescopes comprise: (1) layered synthetic microstructure (LSM) spherical mirrors, (2) thin foil filters, and (3) microchannel plate (MCP) detectors, all enshrouded within the telescope body. The LSM mirrors select the bandpass for each telescope, while rejecting some of the HeII 304{angstrom} geocoronal radiation. The filters, constructed either from aluminum/carbon or Lexan/titanium/boron, serve to strongly reject the geocoronal radiation, as well as longer wavelength emission from bright OB stars. Each telescope detector consists of two plates, the outermost of which is curved to accurately match the spherical focal surface of the mirror. By reviewing the ground and flight histories, this paper analyzes the flight …
Date: July 8, 1999
Creator: Bloch, J.J.; Roussel-Dupre, D. & Starin, S.
System: The UNT Digital Library
The Nova Outburst: Thermonuclear Runaways on Degenerated Dwarfs (open access)

The Nova Outburst: Thermonuclear Runaways on Degenerated Dwarfs

Observational and theoretical studies of the outbursts of classical novae have provided critical insights into a broad range of astrophysical phenomena. Thermonuclear runaways (TNRs) in accreted hydrogen-rich envelopes on the white dwarf (WD) components of close binary systems constitute not only the outburst mechanism for a classical nova explosion, but also the recurrent novae and a fraction of the symbiotic novae explosions. Studies of the general characteristics of these explosions, both in our own galaxy and in neighboring galaxies of varying metallicity, can teach us about binary stellar evolution, while studies of the evolution of nova binary systems can constrain models for the (as yet unidentified) progenitors of Type Ia supernovae. Further, the empirical relation between the peak luminosity of a nova and the rate of decline, which presents a challenge to theoretical models, allows novae to be utilized as standard candles for distance determinations out to the Virgo Cluster. E xtensive studies of novae with IUE and the resulting abundance determinations have revealed the existence of oxygen-neon white dwarfs in some systems. The high levels of enrichment of novae ejecta in elements ranging from carbon to sulfur confirm that there is significant dredge-up of matter from the core of …
Date: July 8, 1999
Creator: Starrfield, S.; Truran, J. W. & Sparks, W. M.
System: The UNT Digital Library
Choosing wind power plant locations and sizes based on electric reliability measures using multiple-year wind speed measurements (open access)

Choosing wind power plant locations and sizes based on electric reliability measures using multiple-year wind speed measurements

To project the US potential to meet future electricity demands with wind energy, estimates of available wind resource and costs to access that resource are critical. The US Department of Energy (DOE) Energy Information Administration (EIA) annually estimates the US market penetration of wind in its Annual Energy Outlook series. For these estimates, the EIA uses wind resource data developed by the Pacific Northwest National Laboratory for each region of the country. However, the EIA multiplies the cost of windpower by several factors, some as large as 3, to account for resource quality, market factors associated with accessing the resource, electric grid impacts, and rapid growth in the wind industry. This paper examines the rationale behind these additional costs and suggests alternatives.
Date: July 8, 1999
Creator: Milligan, M.R. & Artig, R.
System: The UNT Digital Library
Prediction of the lifetime integrity of a nuclear waste container material based on thermal stability studies (open access)

Prediction of the lifetime integrity of a nuclear waste container material based on thermal stability studies

The kinetics of precipitation in C-22 alloy (UNS N06022) was estimated through isothermal aging experiments at temperatures ranging from 427 C to 800 C for times up to 40,000 h. The phases that formed, at least after the longer aging times, were identified by transmission electron microscopy (TEM). Aged samples were also examined using scanning electron microscopy (SEM) to determine when precipitation began on grain boundaries, completely covered grain boundaries, and began forming within the grains. This data was used to evaluate the kinetics of precipitation at lower temperatures using a simple exponential temperature dependent. The corrosion resistance of aged samples was investigated using the ASTM Specification G28B technique. The time to cause a significant increase in corrosion rate was also determined as a function of temperature and was fit to an exponential temperature dependence. Preliminary results indicate that C-22 alloy base metal would remain a highly corrosion resistant, single-phase material for greater than 10,000 years at temperatures below approximately 300 C.
Date: July 8, 1999
Creator: Rebak, R B; Shen, T & Summers, T
System: The UNT Digital Library
The development of Sn-Li coolant/breeding material for APEX/ALPS applications. (open access)

The development of Sn-Li coolant/breeding material for APEX/ALPS applications.

A Sn-Li alloy has been identified to be a coolant/breeding material for D-T fusion applications. The key feature of this material is its very low vapor pressure, which will be very useful for free surface concepts employed in APEX, ALPS and inertial confinement fission. The vapor is dominated by lithium, which has very low Z. Initial assessment of the material indicates acceptable tritium breeding capability, high thermal conductivity, expected low tritium volubility, and expected low chemical reactivities with water and air. Some key concerns are the high activation and material compatibility issues. The initial assessment of this material, for fission applications, is presented in this paper.
Date: July 8, 1999
Creator: Sze, D.-K.
System: The UNT Digital Library
Developing a cross-platform port simulation system. (open access)

Developing a cross-platform port simulation system.

With the advent of networked computer systems that connect disparate computer hardware and operating systems, it is important for port simulation systems to be able to run on a wide variety of computer platforms. This paper describes the design and implementation issues in reengineering the PORTSIM model in order to field the model to Windows-based systems as well as to Unix-based systems such as the Sun, Silicon Graphics, and HP workstations. The existing PORTSIM model was written to run on a Sun workstation running Unix. The model was initially implemented in MODSIM and C and utilized embedded SQL to retrieve port, ship, and cargo data from back-end OMCLE databases. Output reports, graphs, and tables for model results were written in C, utilizing third-party graphics libraries. This design and implementation worked well for the intended hardware platform and configuration, but as the number of model users grew and as the capabilities of the model expanded, a need developed to field the model to varying hardware configurations. This new requirement demanded that the existing design be modified to more easily allow for model fielding and maintenance. A phased approach is described that (1) identifies the existing model from which cross-platform development began, …
Date: July 8, 1999
Creator: Nevins, M. R.
System: The UNT Digital Library