Publications

Understanding the mechanisms of growth during vapor-phase deposition is critical for the precise control of surface morphology required by advanced electronic device structures. Yet only relatively recently have the tools for observing this growth on an atomic-level scale become available (via scanning tunneling microscopy (STM), reflection high energy electron diffraction (RHEED) and low-energy electron microscopy (LEEM)). We present results from our own RHEED and STM measurements in which we use computer simulations to aid in determining the fundamental surface processes which contribute to.the observed structures. In this study of low-energy ion bombardment and growth on Si(001), it is demonstrated how simulations enable us to determine the dominant atomistic process.

Reflective Particle Tags were developed for uniquely identifying individual strategic weapons that would be counted in order to verify arms control treaties. These tags were designed to be secure from copying and transfer even after being lift under the control of a very determined adversary for a number of years. This paper discusses how this technology can be applied in other applications requiring confidence that a piece of equipment, such as a seal or a component of a secure, has not been replaced with a similar item. The hardware and software needed to implement this technology is discussed, and guidelines for the sign of systems that rely on these or similar randomly formed features for security applications are presented. Substitution of identical components is one of the easiest ways to defeat security seals, secure containers, verification instrumentation, and similar equipment. This technology, when properly applied, provides a method to counter this defeat scenario. This paper presents a method for uniquely identifying critical security related equipment. Guidelines for implementing identification systems based on reflective particles or similar random features without compromising their intrinsic security are discussed.

A non-contact, high-resolution laser ranging device has been incorporated into an instrument for accurately mapping the surface of WECS airfoils in the field. Preliminary scans of composite materials and bug debris show that the system has adequate resolution to accurately map bug debris and other surface contamination. This system, just recently delivered and now being debugged and optimized, will be used to characterize blade surface contamination on wind turbines. The technology used in this system appears to hold promise for application to many other measurements tasks, including a system for quickly and very accurately determining the profile of turbine blade molds and blades.

Sandia National Laboratories has completed the design and is now fabricating packages for shipment of tritium gas in conformance with 10 CFR 71. The package, referred to as the AL-SX, is quite unique in that its contents are a radioactive gas, and a large margin of safety has been demonstrated through overtesting. The AL-SX is small, 42 cm in diameter and 55 cm tall, and weighs between 55 kg empty and up to a maximum of 60 kg with contents and is designed for a 20-year service life. This paper describes the design of the AL-SX and certification testing performed on AL-SX packages and discusses containment of tritium and AL-SX manufacturing considerations.

Sandia National Laboratories is one of the nation's largest research and development (R and D) facilities and is responsible for national security programs in defense and energy with a primary emphasis on nuclear weapon R and D. However, Sandia also supports a wide variety of projects ranging from basic materials research to the design of specialized parachutes. As a multiprogram national laboratory, Sandia has much to offer both industrial and government customers in pursuing space nuclear technologies. A brief summary of Sandia's technical capabilities, test facilities, and example programs that relate to military and civilian objectives in space is presented.

Sandia National Laboratories is actively involved in testing coated particle nuclear fuels for the Space Nuclear Thermal Propulsion (SNTP) program managed by Phillips Laboratory. The testing program integrates the results of numerous in-pile and out-of-pile tests with modeling efforts to qualify fuel and fuel elements for the SNTP program. This paper briefly describes the capabilities of the Annular Core Research Reactor (in which the experiments are performed), the major in-pile tests, and the models used to determine the performance characteristics of the fuel and fuel elements. 6 refs.

The US Department of Energy's Slant Hole Completion Test Well, SHCT-1, was drilled in 1990 into gas-bearing, lenticular and blanket-shaped sandstones of the Mesaverde Formation, northwestern Colorado. The reservoirs are over-pressured, with sub-microdarcy, in situ, matrix-rock permeabilities. However, a set of sub-parallel natural fractures increases the whole-reservoir permeabilities, measured by well tests, to several tens of microdarcies. The slant hole azimuth was therefore oriented to cut across the dominant fracture strike, in order to access the natural-fracture permeability and increase drainage into the wellbore.

Advection-dominated flows occur widely in the transport of groundwater contaminants, the movements of fluids in enhanced oil recovery projects, and many other contexts. In numerical models of such flows, adaptive local grid refinement is a conceptually attractive approach for resolving the sharp fronts or layers that tend to characterize the solutions. However, this approach can be difficult to implement in practice. A domain decomposition method developed by Bramble, Ewing, Pasciak, and Schatz, known as the BEPS method, overcomes many of the difficulties. We demonstrate the applicability of the iterative BEPS ideas to finite-element collocation on trial spaces of piecewise Hermite bicubics. The resulting scheme allows one to refine selected parts of a spatial grid without destroying algebraic efficiencies associated with the original coarse grid. We apply the method to two dimensional time-dependent advection-diffusion problems.

Three methods of evaluating accelerated battery test data are described. Criteria for each method are used to determine the minimum test matrix required for accurate predictions. Other test methods involving high current discharge and real time techniques are discussed.

Computational mechanics simulation capability via the finite element method is being integrated into the FASTCAST project to allow realistic analyses of investment casting problems. Commercial and in-house software is being coupled to new, solid model based mesh generation capabilities to provide improved access to fluid, thermal and structural simulations. These simulations are being used for the validation of complex gating designs and the study of fundamental problems in casting.

This document presents recent accomplishments in engineering and science at Sandia National Laboratories. Commercial-scale parabolic troughs at the National Solar Thermal Test Facility are used for such applications as heating water, producing steam for industrial processes, and driving absorption air conditioning systems. Computerized-aided design, superconductor technology, radar imaging, soldering technology, software development breakthroughs are made known. Defense programs are exhibited. And microchip engineering applications in test chips, flow sensors, miniature computers, integrated circuits, and microsensors are presented.

Diffraction peaks can occur as unidentifiable peaks in the energy spectrum of an x-ray spectrometric analysis. Recently, there has been increased interest in oriented polycrystalline films and epitaxial films on single crystal substrates for electronic applications. Since these materials diffract x-rays more efficiently than randomly oriented polycrystalline materials, diffraction peaks are being observed more frequently in x-ray fluorescent spectra. In addition, micro x-ray spectrometric analysis utilizes a small, intense, collimated x-ray beam that can yield well defined diffraction peaks. In some cases these diffraction peaks can occur at the same position as elemental peaks. These diffraction peaks, although a possible problem in qualitative and quantitative elemental analysis, can give very useful information about the crystallographic structure and orientation of the material being analyzed. The observed diffraction peaks are dependent on the geometry of the x-ray spectrometer, the degree of collimation and the distribution of wavelengths (energies) originating from the x-ray tube and striking the sample.

Geologic materials are often modeled with discrete spheres because the material is not continuous and discrete spherical models simplify the mathematics. Spherical element models have been created using assemblages of spheres with a specified particle size distribution or by assuming the particles are all the same size and making the assemblage a close-packed array of spheres. Both of these approaches yield a considerable amount of material dilatation upon movement. This has proven to be unsatisfactory for sedimentary rock formations that contain bedding planes where shear movement can occur with minimal dilatation of the interface. A new concept referred to as packing angle has been developed to allow the modeler to build arrays of spheres that are the same size but have the rows of spheres offset from each other. ne row offset is a function of the packing angle and allows the modeler to control the dilatation as rows of spheres experience relative horizontal motion.

The syntheses and physical properties of {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]X (X=Br and Cl) are summarized. The {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br salt is the highest {Tc} radical-cation based ambient pressure organic superconductor ({Tc}=11.6 K), and the {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl salt becomes a superconductor at even higher {Tc} under 0.3 kbar hydrostatic pressure ({Tc}=12.8 K). The similarities and differences between {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br and {kappa}-(ET){sub 2}Cu(NCS){sub 2} ({Tc}=10.4 K) are presented. The X-ray structures at 127 K reveal that the the S{hor_ellipsis}S contacts shorten between ET dimers in the former compound while the S{hor_ellipsis}S contacts shorten within dimers in the latter. The difference in their ESR linewidth behavior is also explained in terms of the structural differences. A semiconducting compound, (ET)Cu[N(CN){sub 2}]{sub 2}, isolated during {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl synthesis is also reported. The ESR measurements of the {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl salt indicate that the phase transition near 40 K is similar to the spin density wave transition in (TMTSF){sub 2}SbF{sub 6}. A new class of organic superconductors, {kappa}-(ET){sub 2}Cu{sub 2}(CN){sub 3} and {kappa}-(ET){sub 2}Cu{sub 2}(CN){sub 3}-{delta}Br{delta}, is reported with {Tc}`s of 2.8 K (1.5 kbar) and 2.6 K (1 kbar), respectively.

Nuclear weapons system designers and safety analysts are contemplating broader use of probabilistic risk assessment techniques. As an aid to their understanding, this document summarizes the development and use of probabilistic risk assessment (PRA) techniques in the nuclear power industry. This report emphasizes the use of PRA in decision making with the use of case studies. Nuclear weapon system designers and safety analysts, contemplating the broader use of PRA techniques, will find this document useful.

This document contains implementation details for the Quality Information Management System (QIMS) Pilot Project, which has been released for VAX/VMS systems using the INGRES RDBMS. The INGRES Applications-By-Forms (ABF) software development tool was used to define the modules and screens which comprise the QIMS Pilot application. These specifications together with the QIMS information model and corresponding database definition constitute the QIMS technical specification and implementation description presented herein. The QIMS Pilot Project represents a completed software product which has been released for production use. Further extension projects are planned which will release new versions for QIMS. These versions will offer expanded and enhanced functionality to meet further customer requirements not accommodated by the QIMS Pilot Project.

A large buildup in interface traps has been observed in commercial and radiation-hardened MOS transistors at very long times after irradiation (> 10{sup 6} s). This latent buildup may have important implications for CMOS response in space. 13 refs.

Translations of two pioneering Russian papers on antenna theory are presented. The first paper provides a treatise on finite-length dipole antennas; the second paper addresses infinite-length, impedance-loaded transmitting antennas.

A new approach for solving two-dimensional clustering problems is presented. The method is based on an inhibitory template which is applied to each pair of dots in a data set. Direct clustering of the pair is inhibited (allowed) if another dot is present (absent), respectively, within the area of the template. The performance of the method is thus entirely determined by the shape of the template. Psychophysical experiments have been used to define the template shape for this work, so that the resulting method requires no pattern-dependent adjustment of any parameters. The novel concept of a psychophysically-defined template and the absence of adjustable parameters set this approach apart from previous work. The useful grouping performance of this approach is demonstrated with the successful grouping of a variety of dot patterns selected from the clustering literature.

Sandia National Laboratories (SNL) Environmental Restoration (ER) Program has recently implemented a highly structured CS{sup 2} required by DOE. It is a complex system which has evolved over a period of a year and a half. During the implementation of this system, problem areas were discovered in cost estimating, allocation of management costs, and integration of the CS{sup 2} system with the Sandia Financial Information System. In addition to problem areas, benefits of the system were fund in the areas of schedule adjustment, projecting personnel requirements, budgeting, and responding to audits. Finally, a number of lessons were learned regarding how to successfully implement the system.

Ferroelectric PZT 53:47 thin films were prepared by two different solution deposition methodologies. Both routes utilized carboxylate and alkoxide precursors and acetic acid, which served as both a solvent and a chemical modifier. We have studied the effects of solution preparation conditions on film microstructure and ferroelectric properties, and have used NMR spectroscopy to characterize chemical differences between the two precursor solutions. Films prepared by a sequential precursor addition (SPA) process were characterized by slightly lossy hysteresis loops, with a P{sub r} of 18.7 {mu}C/cm{sup 2} and an E{sub c} of 55.2 kV/cm. Films prepared by an inverted mixing order (IMO) process were characterized by well saturated hysteresis loops, a P{sub r} of 26.2 {mu}C/cm{sup 2} and an E{sub c} of 43.3 kV/cm. While NMR investigations indicated that the chemical environments of both the proton and carbon species were similar for the two processes, differences in the amounts of by-products (esters, and therefore, water) formed were noted. These differences apparently impacted ceramic microstructure. Although both films were characterized by a columnar growth morphology, the SPA derived film displayed a residual pyrochlore layer at the film surface, which did not transform into the stable perovskite phase. The presence of this layer resulted in poor dielectric properties and lossy ferroelectric behavior.

We have developed a video detection algorithm for measuring the residue left on a printed circuit board after a soldering process. Oblique lighting improves the contrast between the residue and the board substrate, but also introduces an illumination gradient. The algorithm uses the Boundary Contour System/Feature Contour System to produce an idealized clean board image by discounting the illuminant, detecting trace boundaries, and filling the trace and substrate regions. The algorithm then combines the original input image and ideal image using mathematical models of the normal and inverse Weber Law to enhance the residue on the traces and substrate. The paper includes results for a clean board and one with residue.

CEPXS/ONELD is a discrete ordinates transport code package that can model the electron-photon cascade from 100 MeV to 1 keV. The CEPXS code generates fully-coupled multigroup-Legendre cross section data. This data is used by the general-purpose discrete ordinates code, ONELD, which is derived from the Los Alamos ONEDANT and ONETRAN codes. Version 1.0 of CEPXS/ONELD was released in 1989 and has been primarily used to analyze the effect of radiation environments on electronics. Version 2.0 is under development and will include user-friendly features such as the automatic selection of group structure, spatial mesh structure, and S{sub N} order.

Changing the focus of a corporate compensation and performance review system from process orientation to data base orientation results in a more integrated and flexible design. Data modeling of the business system provides both systems and human resource professionals insight into the underlying constants of the review process. Descriptions of the business and data modeling processes are followed by a detailed presentation of the data base model. Benefits derived from designing a system based on the model include elimination of hard-coding, better audit capabilities, a consistent approach to exception processing, and flexibility of integrating changes in compensation policy and philosophy.

This paper will address the purpose, scope, and approach of the Department of Energy Tiger Team Assessments. It will use the Tiger Team Assessment experience of Sandia National Laboratories at Albuquerque, New Mexico, as illustration.