Publications

The image blur in a photograph is produced by the exposure of a moving object. Knowing the amount of image blur is important for recording useful data. If there is too much blur, it becomes hard to make quantitative measurements. This report discusses image blur, the parameters used to control it, and how to calculate it.

This report summarizes the purchasing and transportation activities of the Purchasing and Materials Management Organization for Fiscal Year 1992. Activities for both the New Mexico and California locations are included. Topics covered in this report include highlights for fiscal year 1992, personnel, procurements (small business procurements, disadvantaged business procurements, woman-owned business procurements, New Mexico commercial business procurements, Bay area commercial business procurements), commitments by states and foreign countries, and transportation activities. Also listed are the twenty-five commercial contractors receiving the largest dollar commitments, commercial contractors receiving commitments of $1,000 or more, integrated contractor and federal agency commitments of $1,000 or more from Sandia National Laboratories/New Mexico and California, and transportation commitments of $1,000 or more from Sandia National Laboratories/New Mexico and California.

This document is the Operations Manual for the Beneficial Uses Shipping System (BUSS) cask. These operating instructions address requirements; for loading, shipping, and unloading, supplementing general operational information found in the BUSS Safety Analysis Report for Packaging (SARP), SAND 83-0698. Use of the BUSS cask is authorized by Department of Energy (DOE) and Nuclear Regulatory Commission (NRC) for the shipment of special form cesium chloride or strontium flouride capsules.

Environmental monitoring, earth-resource mapping, and military systems require broad-area imaging at high resolutions. Many times the imagery must be acquired in inclement weather or during night as well as day. Synthetic aperture radar (SAR) provides such a capability. SAR systems take advantage of the long-range propagation characteristics of radar signals and the complex information processing capability of modern digital electronics to provide high resolution imagery. SAR complements photographic and other optical imaging capabilities because of the minimum constrains on time-of-day and atmospheric conditions and because of the unique responses of terrain and cultural targets to radar frequencies. Interferometry is a method for generating a three-dimensional image of terrain. The height projection is obtained by acquiring two SAR images from two slightly differing locations. It is different from the common method of stereoscopic imaging for topography. The latter relies on differing geometric projections for triangulation to define the surface geometry whereas interferometry relies on differences in radar propagation times between the two SAR locations. This paper presents the capabilities of SAR, explains how SAR works, describes a few SAR applications, provides an overview of SAR development at Sandia, and briefly describes the motion compensation subsystem.

Atomic layer epitaxy (ALE) of Si has been demonstrated by using remote He plasma low energy ion bombardment to desorb H from an H-passivated Si(100) surface at low temperaturea and subsequently chemisorbing Si2H6 on the surface in a self-limiting fashion. Si substrates were prepared using an RCA clean followed by a dilute HF dip to provide a clean, dihydride-terminated (1 × 1) surface, and were loaded into a remote plasma chemical vapor deposition system in which the substrate is downstream from an r.f. noble gas (He or Ar) glow discharge in order to minimize plasma damage. An in situ remote H plasma clean at 250°C for 45 min was used to remove surface O and C and to provide an alternating monohydride and dihydride termination, as evidenced by a (3 × 1) reflection high energy electron diffraction (RHEED) pattern. It was found necessary to desorb the H from the Si surface to create adsorption sites for Si- bearing species such as Si2H6. Remote He plasma bombardment for 1-3 min was investigated over a range of temperature (250°C-410°C), pressures (50-400 mTorr) and r.f. powers (6-30 W) in order to desorb the H and to convert the (3 × 1) RHEED pattern to a (2 × 1) pattern which is characteristic of either a monohydride termination or a bare Si surface. It was found that as He pressures and r.f. powers are raised the plasma potential and mean free paths are reduced, leading to lower He bombardment energies but higher fluxes. Optimal He bombardment parameters were determined to be 30 W at 100 mTorr process pressure at 400°C for 1-3 min. He was found to be more effective than Ar bombardment because of the closer match of the He and H masses compared with that between Ar and H. Monte Carlo TRIM simulations of He and Ar bombardment of H-terminated Si surfaces were performed 3o validate this hypothesis and to predict that approximately 3 surface H atoms were displaced by the incident He atoms, with no bulk Si atom displacement for He energies in the range 15-60 eV. The He bombardment cycles were followed by Si2H6 dosing over a range of partial pressures (from 10-7 Torr to 1.67 mTorr), temperatures (250°C-400°C) and times (from 20s to 3 min) without plasma excitation, because it is believed that Si2H6 can chemisorb in a self-limiting fashion on a bare Si surface as two silyl (SiH3) species, presumably leading to a H-terminated surface once again. The Si2H6 dosing pressures and times corresponded to saturation dosing (about 106 langmuirs). Alternate Si2H6 dosing and He low energy ion bombardment cycles (about 100-200) were performed to confirm the ALE mode of growth. It was found that the growth per cycle saturates with long Si2H6 dosing at a level which increases slightly with He bombardment time. At 400°C, for 2 min He bombardment at 100 mTorr and 30 W, the growth per cycle saturates at about 0.1 monolayers cycle-1, while for 3 min He bombardment the Si growth saturates at about 0.15 monolayers cycle-1. It was also confirmed that the growth is achieved only by using alternate He bombardment and Si2H6 dosing. He bombardment alone for a comparable time (3 min × 100 cycles) causes a negligible change in the Si film thickness (less than 5 Å). Similarly, thermal growth using Si2H6 under these conditions for (3 min × 100 cycles) causes negligible deposition (less than 5 Å). © 1993.

Given a planar straight-line graph, we find a covering triangulation whose maximum angle is as small as possible. A covering triangulation is a triangulation whose vertex set contains the input vertex set and whose edge set contains the input edge set. Such a triangulation differs from the usual Steiner triangulation in that we may not add a Steiner vertex on any input edge. Covering triangulations provide a convenient method for triangulating multiple regions sharing a common boundary, as each region can be triangulated independently. As it is possible that no finite covering triangulation is optimal in terms of its maximum angle, we propose an approximation algorithm. Our algorithm produces a covering triangulation whose maximum angle {gamma} is probably close to {gamma}{sub opt}, a lower bound on the maximum angle in any covering triangulation of the input graph. Note that we must have {gamma} {le} 3{gamma}{sub opt}, since we always have {gamma}{sub opt} {ge} {pi}/3 and no triangulation can contain an angle of size greater than {pi}. We prove something significantly stronger. We show that {pi} {minus} {gamma} {ge} ({pi} {minus} {gamma}{sub opt})/6, i.e., our {gamma} is not much closer to {pi} than is {gamma}{sub opt}. This result represents the first nontrivial bound on a covering triangulation`s maximum angle. We require a subroutine for the following problem: Given a polygon with holes, find a Steiner triangulation whose maximum angle is bounded away from {pi}. No angle larger than 8{pi}/9 is sufficient for the bound on {gamma} claimed above. The number of Steiner vertices added by our algorithm and its running time are highly dependent on the corresponding bounds for the subroutine. Given an n-vertex planar straight-line graph, we require O(n + S(n)) Steiner vertices and O(n log n + T(n)) time, where S(n) is the number of Steiner vertices added by the subroutine and T(n) is its running time for an O(n)-vertex polygon with holes.

One proven method of evading the detection of a nuclear test is to decouple the explosion with a large air-filled cavity. Past tests have shown it is possible to substantially reduce the seismic energy emanating from a nuclear explosion by as much as two, orders of magnitude. The problem is not whether it can be done; the problem is the expense involved in mining a large cavity to fully decouple any reasonable size test. It has been suggested that partial decoupling may exist so some fraction of decoupling may be attained between factors of 1 to 100. MISTY ECHO and MINERAL QUARRY are two nuclear tests which were instrumented to look at this concept. MISTY ECHO was a nuclear explosion conducted in an 11 m hemispherical cavity such that the walls were over driven and reacted in a non-linear manner. MINERAL QUARRY was a nearby tamped event that is used as a reference to compare with MISTY ECHO. The scaled cavity radius of MISTY ECHO was greater than 2m/kt[sup l/3]. Both of these tests had free-field accelerometers located within 400 m of their respective sources. Analysis of surface ground motion is inconclusive on the question of partial decoupling. This is due to the difference in medium properties that the ray paths take to the surface. The free-field configuration alleviates this concern. The analysis consists of cube-root signal MINERAL QUARRYs signal to MISTY ECHO's yield and calculating the ratio of the Fourier amplitudes of both the acceleration and the reduced displacement potentials. The results do not indicate the presence of partial decoupling. In fact, there is a coupling enhancement factor of 2.

Hazardous operations which involve the dextrous manipulation of dangerous materials in the field have, in the past, been completed by technicians. Use of humans in such hazardous operations is under increased scrutiny due to high costs and low productivity associated with providing protective clothing and environments. Remote systems are needed to accomplish many tasks such as the clean up of waste sites in which the exposure of personnel to radiation, chemical, explosive, and other hazardous constituents is unacceptable. Traditional remote manual field operations have, unfortunately, proven to have very low productivity when compared with unencumbered human operators. Recent advances in the integration of wars and computing into the control of remotely operated equipment have shown great promise for reducing the cost of remote systems while providing faster and safer remote systems. This paper discusses applications of such advances to remote field operations.

Multiple tracer techniques were used to estimate recharge rates through unsaturated alluvium beneath the Greater Confinement Disposal site, a waste disposal site located in Frenchman Flat, on the Nevada Test Site. Three tracers of soil water movement -- meteoric chloride, stable isotopes of water, and cosmogenic chlorine-36 -- yielded consistent results indicating that recharge rates were negligible for the purpose of performance assessment at the site.

This report describes work performed for the development of a fiber-optic shock position sensor used to measure the location of a shock front in the neighborhood of a nuclear explosion. Such a measurement would provide a hydrodynamic determination of nuclear yield. The original proposal was prompted by the Defense Nuclear Agency`s interest in replacing as many electrical sensors as possible with their optical counterparts for the verification of a treaty limiting the yield of a nuclear device used in underground testing. Immunity to electromagnetic pulse is the reason for the agency`s interest; unlike electrical sensors and their associated cabling, fiber-optic systems do not transmit to the outside world noise pulses from the device containing secret information.

A robotic rover vehicle designed for use in the exploration of the Lunar surface is described. The Robotic All-Terrain Lunar Exploration Rover (R-A.T.L.E.R-) is a four wheeled all-wheel-drive dual-body vehicle. A uniquely simple method of chassis articulation is employed which allows all four wheels to remain in contact with the ground, even while climbing over step-like obstacles as large as {approximately}1.3 wheel diameters. Skid steering and modular construction are used to produce a simple, rugged, highly agile mobility chassis with fewer parts required compared to other designs being considered for planetary exploration missions. The design configuration, mobility parameters, and performance of several existing R.A.T.L.E.R prototypes are discussed, with emphasis on an analysis of the configuration parameters which directly affect the designs mobility performance.

This paper describes the connection between mechanical degradation of common cable materials in radiation and elevated temperature environments and density increases caused by the oxidation which leads to this degradation. Two techniques based on density changes are suggested as potential non-destructive evaluation (NDE) procedures which may be applicable to monitoring the mechanical condition of cable materials in power plant environments. The first technique is direct measurement of density changes, via a density gradient column, using small shavings removed from the surface of cable jackets at selected locations. The second technique is computed X-ray tomography, utilizing a portable scanning device.

We technologists generally only address risk magnitudes in our analyses, although other studies have found nineteen additional dimensions for the way the public perceives risk. These include controllability, voluntariness, catastrophic potential, and trust in the institution putting forth the risk. We and the geneml public use two different languages, and to understand what their concerns are, we need to realize that the culture surrounding nuclear weapons is completely alien to the general public. Ultimately, the acceptability of a risk is a values question, not a technical question. For most of the risk dimensions, the public would perceive no significant difference between using oralloy and plutonium. This does not mean that the suggested design change should not be proposed, only that the case for, or against, it be made comprehensively using the best information available today. The world has changed: the ending of the cold war has decreased the benefit of nuclear weapons in the minds of the public and the specter of Chernobyl has increased the perceived risks of processes that use radioactive materials. Our analyses need to incorporate the lessons pertinent to this newer world.

This is the final report for a study performed for the 1992 LDRD spaceborne SAR (Synthetic Aperture Radar) study. This report presents an overview of some of the issues that must be considered for design and implementation of a SAR on a spaceborne platform. The issues addressed in this report include: a survey of past, present, and future spaceborne SARs; pulse-repetition frequency (PRF); general image processing issues; transmitter power requirements; the ionosphere; antennas; two case studies; and an appendix with a simplified presentation on geometry and orbits.

Damage induced during electron-beam metallization results in a three-order-of-magnitude increase in the generation rate of bulk GaAs. The damage appears to be radiation induced, with low-energy electrons being the most likely from p{sup +}-i-n-i-p{sup +}-GaAs layers damaging mechanism.

This report describes the design, development, manufacturing processes, acceptance equipment, test results, and conclusions for the SA3581/MC4196 LAC program. Four development groups (Identified as Groups 1 through 3 and a Proof of Development Build) provided the evaluation criteria for the PPI/TMS production units.

An ever increasing demand for highly rugged, miniature AT strip resonators prompted the development of a resonator package for use in high-g shock applications. This package, designed and developed by Statek Corporation, is based on the package configuration currently being used by Statek for commercial devices. This report describes the design intent, component characteristics, and evaluation test results for this device.

A temperature between 400 and 500 and a pressure between 40 MPa and 160 MPa were indicated by a two-factor, three-level factorial experiment for diffusion bonding of molybdenum sheet substrates. These substrates were sputter ion plated with palladium (0.5 {mu}m) and silver (10 {mu}m) films on the mating surfaces, with the silver used as a bonding interlayer. The palladium acted as an adhesive layer between the silver film and molybdenum substrate. The silver diffusion bonds that resulted were qualitatively characterized at the interfacial regions, and bonds with no visible interface were obtained at 750OX magnification. Correlations were obtained for voids found optically at the silver/silver bonding interface and colored image maps, illustrating bond quality, produced by nondestructive ultrasonic imaging. Above 160 MPa, the bonding process produces samples with a nonuniform load distribution. These samples contained regions with gaps and well-bonded regions at the silver/silver interface, and all had macroscopic deformation of the silver films.

Salford Electrical Instruments, Ltd., and the General Electric Company`s Hirst Research Centre, under contract to the United Kingdom`s (UK) Ministry of Defence, developed a radiation-hard, leadless chip-carrier-packaged oscillator/divider. Two preproduction clocks brought to Sandia National Laboratories (SNL) by a potential SNL customer underwent mechanical and thermal environmental evaluation. Because of the subsequent failure of one device and the deteriorating condition of another device, the devices were not subjected to radiation tests. This report describes the specifics of the environmental evaluation performed on these two clocks and the postmortem analysis of one unit, which ultimately failed. Clock startup time versus temperature studies were also performed and compared to an SNL-designed clock having the same fundamental frequency.

High speed flash radiography has been used to record phenomena that occur during rapid dynamic events. The events are difficult, if not impossible, to record by other means due to the speed of the event or the obscuration associated with it. To eliminate the motion blur of objects moving at high speeds it is necessary to have extremely short exposure times. This short exposure time requires the use of high speed intensifying screens and high speed x-ray film to record the radiographic image. Technicians who use flash x-rays have to depend on recommendations from present and former flash x-ray users for film and screen selection. The film and screen industry has made many changes in the last few years. It is not uncommon to find that the particular film or screen used in the past is no longer manufactured. This paper will describe some of the films and screens that are currently used for testing. It will also describe the optimum experimental setup used to obtain the best images.

A new class of inorganic ion exchange materials that can separate low parts per million level concentrations of Cs{sup +} from molar concentrations of Na{sup +} has recently been developed as a result of a collaborative effort between Sandia National Laboratories and Texas A&M University. The materials, called crystalline silicotitanates, show significant potential for application to the treatment of aqueous nuclear waste solutions, especially neutralized defense wastes that contain molar concentrations of Na{sup +} in highly alkaline solutions. In experiments with alkaline solutions that simulate defense waste compositions, the crystalline silicotitanates exhibit distribution coefficients for Cs{sup +} of greater than 2,000 ml/g, and distribution coefficients greater than 10,000 for solutions adjusted to a pH between 1 and 10. Additionally, the crystalline silicotitanates were found to exhibit distribution coefficients for Pu and Sr{sup 2+} of greater than 2,000 and 100,000 respectively. Development of these materials for use in processes to treat defense waste streams is currently being pursued.

The effects of the midgap-level interface trap density and net oxide charge on the total-dose gain degradation of a bipolar transistor are separately identified. The superlinear dose dependence of the excess base current is explained.

MOS total-dose response is shown to depend strongly on transistor gate length. Simple scaling models cannot predict short-channel device response from long-channel results. Hardness assurance implications are discussed for weapon and space environments.

The discrete Fourier transform (DFT) is used frequently used in the computation of the signal-to-noise ratio (SNR) and harmonic distortion. To estimate the SNR or harmonic distortion, a sine wave is applied to the digitizing system under test. When the data record contains an integer number of cycles of the sine wave, energy from the sine wave and its harmonics does not leak into adjacent DFT frequency bins. Each harmonic occupies one an only one DFT frequency bin. To find the root-mean-square (RMS) value of a harmonic from its DFT, one computes the magnitude of the DFT value at the single frequency of the harmonic. When the DFTs of the fundamental and its harmonics are single lines, the SNR and harmonic distortion are easy to compute. When the data record contains a non-integer number of cycles of the sine wave, energy leaks from the sine wave and its harmonics to adjacent frequencies. The literature contains several approaches to problem of determining which DFT components correspond to a sine wave harmonic. This paper describes how to estimate the RMS value of a sine wave from its DFT with special attention to the selection of the DFT window. The set of DFT frequencies which comprise a harmonic depends on the DFT window, the length of the DFT, and the number of bits of the digitizer. Criteria are developed for choosing the DFT frequencies that correspond to a sine wave. These criteria lead to better choices of DFT windows for SNR and harmonic distortion calculations.

We have studied intrinsic free-carrier recombination in a variety of GaAs structures, including: OMVPE- and MBE-prepared GaAs/Al{sub x}Ga{sub 1-x}As double heterostructures, Na{sub 2}S passivated GaAs structures and bare GaAs structures. We find OMVPE prepared structures are superior to all of these other structures with 300 K lifetimes of {approximately} 2.5 {mu}s and negligible nonradiative interface and bulkrecombination, and thus are truly surface-free (S < 40 cm/s). Moreover, we observe systematic trends in optical properties versus growth conditions. Lastly, we find that the presence of free-exciton recombination in the low-temperature photoluminescence spectra is a necessary but not sufficient condition for optimal optical properties (i.e. long minority-carrier lifetimes).