We have grown Zn{sub 1-x}Mn{sub x}Te alloys by molecular beam epitaxy and characterized them using x-ray diffraction and low temperature magnetoluminescence. Zn{sub 1-x}Mn{sub x}Te is a dilute magnetic semiconductor (DMS) whose bandgap ranges from the green through the blue part of the spectrum and is therefore of interest for blue LEDs.
A camera with 3-ns time resolution -- and a continuous (> 100-ns) record length -- has been developed to image a 10{sup 12}-10{sup 13} W/cm{sup 2} ion beam for inertial-confinement-fusion experiments. A thin gold Rutherford-scattering foil placed in the path of the beam scatters ions into the camera. The foil is in a near-optimized scattering geometry and reduces the beam intensity seven orders of magnitude. The scattered ions are pinhole imaged onto a 2-D array of 39 p-i-n diode detectors. The output of each detector is recorded on a LeCroy 6880 transient-waveform digitizer. The waveforms are analyzed and combined to produce a 39-pixel movie which can be displayed on an image processor to provide, for example, time-resolved horizontal- and vertical-focusing information.
A survivable debris shield is necessary if very high levels of cleanliness are to be achieved on samples exposed to soft x rays from laboratory simulation sources. These samples, often of optical quality, require a low or zero debris environment in order to distinguish low levels of soft x-ray damage from debris-induced effects. We will describe the development of survivable debris shield technology on the Sandia National Laboratories` Saturn x-ray simulation facility, which permits ultraclean exposure over sample areas of 58 cm{sup 2} {at} {approximately}0.35 cal/cm{sup 2}, 5 cm{sup 2}{at} {approximately}0.8 cal/cm{sup 2}, cm{sup 2}, 2.8 cm{sup 2} {at} {approximately}1.2 cal/cm{sup 2}, and 0.8 cm{sup 2} {at} {approximately}1.5 cal/cm{sup 2} with 3-keV argon K-shell photons. These new fluence-area produce test capabilities represent an order-of-magnitude improvement in the state of the art (previously 0.25 cm{sup 2} {at} {approximately} 1 cal/cm{sup 2} or 1.0 cm{sup 2} {at} {approximately}0.35 cal/cm{sup 2}) for soft x-ray simulators.
Methods which report an ability to determine interstitial oxygen (O{sub i}) in heavily doped silicon include the short baseline (SBL) and the curved baseline (CBL) techniques. Both the SBL and CBL methods are similar with the exception of the calibration. We developed a FORTRAN software package to provide separate methods for calculating O{sub i}. The strength of the software is its ability to rapidly compare methods. We report on a comparison of calculation methods including the ASTM standard test F1188-88 which is used in a calibration, and the SBL and the CBL methods, which are used for the heavily doped silicon to provide reliable results. The O{sub i} values calculated for both virgin and thermally processed silicon are reported.
This paper identifies some of the sources of resistance to change that face Sandia National Laboratories` management, and examines the mechanisms that are being used to minimize the effects of that resistance. The rapid and radical nature of many of the changes now being demanded of Sandia make them all the more likely to meet stiff resistance from within the organization. Sandia`s management has attempted to anticipate some of the sources of resistance to the changes planned for its operating procedures and has taken action to minimize their effects. Within this paper, particular attention is given to those individuals who will not only be most effected by, by may also be required to implement the changes. The change process at Sandia is currently ongoing. It is not complete. No claim is made that all of the changes that will be necessary at Sandia National Laboratories have been recognized, nor that all sources of resistance have been anticipated.
A production vacuum arc remelt (VAR) furnace was modified to enable direct viewing of the metal vapor arc and molten electrode tip during melting of 432 mm dia. alloy 718 electrodes into 508 mm dia. ingots. Diffuse and constricted arcing conditions were characterized using high speed cinematography, standard video format, and monochromatic imaging. Constricted arcing was observed while melting electrodes contaminated with oxide slag of the type used for refractory linings in vacuum induction furnaces. Monochromatic imaging was used in visualize the ion distribution in the arc plasma; these images clearly showed whether the arc operated in a diffuse or constricted model. Diffuse arc melting conditions were very similar to those previously reported in the literature for smaller laboratory sized melts.
In November of 1989, technology transfer became a mission for Sandia National Laboratories, (SNL), with the passage of the National Competitiveness Technology Transfer Act. In order to address the specialized technology transfer needs of small businesses, SNL created and implemented the Technology-Based Regional Economic Development (TRED) program. The TRED model has two major components -- technology assistance (or teaming), and `` widget transfer.`` In the technology assistance component, SNL`s technology resources (expertise, services, and equipment) are made available to companies developing commercial products. In the ``widget transfer`` component, SNL`s intellectual property (patents, copyrights) is placed with private sector firms through various partnership intermediaries
This manual is intended to aid operators of the pressure controller in the Transducer Calibration Laboratory. We include discussions of automated control, data acquisition, and data analysis techniques that improve the quality and thoroughness of transducer pressure calibration procedures.
This memorandum is a synopsis of the description and operation of the equipment used and the events occurring during the calibration of an accelerometer on the 5000 g centrifuge.
Many MoS{sub 2} lubricant film formulations exhibit tribological performance degradation after extended storage in high humidity ambient environments. As a part of an extensive study of the effects of high humidity storage on a wide variety of MoS{sub 2} lubricant film formulations, the effects of high humidity storage on sputtered MoS{sub 2} films have been examined. The surface chemistries of a series of ten different commercially deposited MoS{sub 2} lubricant film formulations on 440C stainless steel have been examined before and after 1 month of storage at 98% relative humidity. While the films varied greatly in film chemistry prior to high humidity storage, many smaller differences were observed after high humidity storage. Addition of Ni to the films affects the film chemistry far more dramatically than the addition of AuPd or SbO{sub x}, facilitating oxidation of the MoS{sub 2} and enhancing formation of sulfate species. All of the films are adequately characterized by considering only MoS{sub 2} and MoO{sub 3} species, with the exception of the films co-sputtered with Ni and ion implanted with N{sup +}, where some MoO{sub 2} or MoS{sub 2-x}O{sub x} must also be present.
This bibliography contains 64 references concerning the management of business and industry. Books and articles are both cited. Methods for gathering and utilizing information are emphasized. (GHH)
A power MOSFET macro-model for use with the circuit simulator SPICE has been developed suitable for use over the temperature range of {minus}55 to 125{degrees}C. The model is comprised of a single parameter set with the temperature dependence accessed through the SPICE TEMP card. This report describes in detail the development of the model and the extraction algorithms used to obtain model parameters. The extraction algorithms are described in sufficient detail to allow for automated measurements which in turn allows for rapid and cost effective development of an accurate SPICE model for any power MOSFET. 22 refs.
The analytical procedures for establishing the fragment hazard zone for explosive test facilities are presented. Environment, safety and health regulations require that a hazard zone analysis be conducted for every explosive test facility. Analyses are presented for explosively driven missile fragment trajectories resultant from cased explosive configurations. Fragment trajectory parameter data are presented in graphical form for three different fragment materials (aluminum, steel and tantalum), initial velocities between 0.6mm/{mu}s (2000 ft/sec) to 4.3mm/{mu}s (14,000 ft/sec), and for various geometries. This trajectory information is used, as an example, to determine the safe distance or hazard zone for the Area 2 explosive test facility at Sandia National Laboratories.
The equations of motion of beam and channel particles are analyzed in the ion focused regime. Using the paraxial approximation and assuming only transverse electro-magnetostatic interactions between beam and channel particles for the equations of motion (the same equations solved in the BUCKSHOT code) are written in non-dimensional form and scaling relations are derived for propagation parameters, magnetic erosion, and evaporation. These relations are very useful in doing parameter studies with a limited number of computer simulations.
Methods of mechanical and thermal testing specifically directed toward evaluation of impact-limiting materials for radioactive material transportation containers are presented. Associated figures of merit and procedures for rank-ordering the materials are also developed. Based on testing and evaluation procedures developed herein, thermal and mechanical results are presented for high- and low-density aluminum honeycombs, polyurethane foams, and aluminum foams. On a minimum mass basis, the high-density aluminum honeycomb is found to be a superior impact energy absorber up to the point of lock up. On a minimum volume basis, the high-density polyurethane foam is far superior, however. Based on the thermal figures of merit, the high-density polyurethane foam was found to be the most favorable material.
The energy-absorbing capability of impact limiters is an important part of radioactive waste transportation system. This document presents the results of the Basic Impact Limiter Study (BILS). The objective of this design development program was to increase the energy-absorbing capabilities of an external impact limiter for both axial and off-axis response. The impact limiter that was evaluated was made of stainless steel and was a right circular cylinder. The evaluation included computer analysis complemented by static and dynamic testing of quater-scale and half-scale models. The design development, analysis, and testing were conducted at Sandia National Laboratories.
Analyses have shown that early rupture of the Mark-I boiling water reactor containment-by the direct action of core debris depends strongly on the time that core debris is superheated above its liquidus. The analyses of the duration of superheat in the core debris are compared to predictions obtained with the CORCON-MOD 3 computer code. The predicitons of this computer code as functions of the core debris mass, composition, and initial superheat are used to create a polynomial response surface. This response surface is used in a Monte Carlo analysis to produce probability distributions for the duration of superheat in core debris in the drywell of a Mark-I containment. It is concluded that to a high level of confidence (>90%) the duration of superheating predicted with the CORCON-MOD 3 code is less than what has been used in the analyses of the threats to the Mark-I containment liner. Based on these results, to the extent superheat duration dictates the threat to the liner, analyses in NUREG/CR-5423 would appear to overestimate the threat to the liner in comparison to threats estimated using the predictions of the duration of superheating obtained with CORCON-MOD 3.
A postnotification record is required for all Highway Route Controlled Quantities of radioactive materials that are shipped in the United States. These reports, which are required by 49 CFR 172.203(d), are compiled in the Radioactive Materials Routing Report (RAMRT) database at the US Department of Transportation (DOT). Sandia National Laboratories` has developed an expanded version of the RAMRT which is entitled the Radioactive Materials Postnotification (RAMPOST) database. This paper provides the summary detail on the following topics: major carriers of highway route controlled quantities, major US Department of Energy (DOE) shippers, major US Nuclear Regulatory Commission (NRC) shippers and a breakdown of the types of Highway Route Controlled Quantities that have been shipped for the time period 1985--1990.
We describe the design and operation of an optical fiber accelerometer intended for environments inhospitable to electronic components. An overview of the device is presented along with descriptions of the optical, electronic, and mechanical components. The performance of the current prototype is equivalent to state of the art piezoelectric accelerometers. Improvements to the current design are discussed.
The possibility of formulating and validating a multi-site, multi- solute model for prediction of contaminant transport in groundwaters is being evaluated through experiments with simple analog systems. These systems consist of mixtures of well-characterized synthetic and natural materials in which the effects of sorption by ion exchange and amphoteric sites are isolated. Initial results are reported for studies of lead sorption by mixtures of goethite and montmorillonite, and Ni-Sr and Pb-Sr ion exchange by montmorillonite. The results of studies of simple clay-oxide mixtures indicate that the pH-dependent sorption behavior of Ni by mixtures of minerals containing amphoteric sites can be predicted from the properties of the component minerals.
In this summary, we re-evaluate estimates of trapped-hole energies inferred from TSC measurements and transistor annealing studies. Improved estimates of the trapped-hole ``attempt-to-escape`` frequency ({upsilon}{sub A}) and a quantitative treatment of (Schottky) electric-field induced barrier lowering strongly suggest that previous estimates of trapped-hole energies in TSC and transistor annealing studies are too low. Moreover, we show that TSC measurements can be modeled analytically from first principles, and the resulting model can accurately predict TSC measurements under arbitrary heating conditions. Finally, we evaluate the dependence of electron trapping in irradiated SiO{sub 2} on dose and on electric field during irradiation. 30 refs.
Site characterization is an integral component of any environmental assessment or restoration project. However, it is often difficult to know how to prioritize site characterization activities. In the absence of a preliminary analysis, site characterization decisions are sometimes guided by little more than intuition. The objective of this paper is to show that a Performance Assessment Methodology, used very early in a project, can be a useful tool for guiding site characterization activities. As an example, a ``preliminary`` performance assessment for the Greater Confinement Disposal project is used to demonstrate implementation of the methodology.
We present results that correlate microstructure and mechanical evolution to variations of deformation rate, hold time and environmental effects on the thermomechanical fatigue (TMF) behavior of 60Sn-40Pb solder. The results are used to define valid conditions for performing accelerated TMF tests. TMF tests at deformation rates of 5.6{times}10{sup {minus}4}s{sup {minus}1}, 2.8{times}10{sup {minus}4}s{sup {minus}1} and 2.1{times}10{sup {minus}4}s{sup {minus}1} were performed. Deformation rates greater than 2.8{times}10{sup {minus}4}s{sup {minus}1} result in fewer cycles to failure. At low deformation rates, the microstructure heterogeneously coarsens at cell boundaries. At higher rates, the deformation mechanism changes, and heterogeneous coarsening occurs at a strain concentration in the joint, independent of the microstructure. TMF tests with hold times of 0, 3 and 6 min. at the temperature extremes were performed. At hold times 3 min. or longer the damage at cell boundaries is annealed, resulting in heterogeneous coarsening. With no hold times the TMF life was greatly enhanced as a result of limited coarsening. The effect of the oxygen environment was explored. The TMF life in the presence of oxygen was found to be extended. Valid acceleration conditions for a TMF test of solder are: a deformation rate of 2.8{times}10{sup {minus}4}s{sup {minus}1} or lower, with hold times of 3 mn. or longer.
A new, laser-based system has been developed for rapid evaluation of monolithic thermoluminescence dosimetry (TLD) arrays. A precision controlled CO{sub 2} laser is used to sequentially heat 1.5 mm diameter, {approx} 0.04 mm thick TLDs deposited on a .125 mm thick polymer substrate in a 3 mm {times} 3 mm grid. Array areas up to 30 cm {times} 30 cm are used (> 10,000 TLD elements), with evaluation times of 45--90 minutes. Isodose contours and various analysis functions are available on the system-operating PC. This system allows for greatly expanded dosimetry compared to standard TLDs, simultaneously decreasing effort and record keeping. We compared the dosimetric characteristics of this system with standard techniques, using near Si-equivalent CaF{sub 2}:Mn TLD elements, in a test with 19 MeV end-point X radiation. The results show the laser system performs as well as the standard system. 4 refs.
The Chemical Waste Landfill (CWL) was used by Sandia National Laboratories (SNL), Albuquerque for disposal of hazardous chemicals from the years 1962 to 1985. Prompted by the detection of low levels of trichlorethylene (TCE) in groundwater samples from a water table aquifer approximately 146 meters below ground surface, a RCRA Site Investigation (RSI) and remediation of organic contaminants will be performed at the CWL prior to closure of this landfill. The RSI is focused on optimal characterization of the VOC and dense non-aqueous phase liquid (DNAPL) contamination at this site which will be possible through application of innovative strategies for characterization and promising new technologies. This paper provides a discussion of conceptual models of contaminant transport at the CWL, and an overview of our investigative strategy which is focused on characterizing transport of VOC and DNAPLS. Each stage of the RSI has been developed to gather information which will reduce the uncertainty in the design of each subsequent phase of the investigation. Three stages are described; a source characterization stage, unsaturated zone characterization stage, and a saturated zone characterization stage. The unsaturated zone characterization must provide all data necessary to make decisions concerning the necessity of a saturated zone characterization phase.