Results of a continuing in situ study of the ion-irradiation-modified crystallization of amorphous CoSi{sub 2} thin films are discussed. 1.5 MeV Kr ion irradiation is employed at 90 K to mix'' nominally amorphous, as-deposited material for subsequent epitaxial regrowth at 450 K. The ion irradiation also is employed at 300 K to produce ion-assisted crystallization. The average degree of transformation per ion is approximately 4 {times} 10{sup {minus}20} cm{sup 3} per ion. The resultant number density of crystals, however, depends sensitively on prior treatment of the film. For example, 300 kV electron irradiation at 300 K prior to ion irradiation may result in a large number density of crystal nuclei. Low dose Kr irradiation at 300 K may also cause a slight increase in the number density of crystals formed subsequently at 450 K, while large Kr doses at 300 K (> 3 {times} 10{sup 14} cm{sup {minus}2}) may double the subsequent thermal growth rate at 450 K. These results are discussed qualitatively in terms of nucleation and growth theory. 8 refs., 6 figs.

The in situ ion irradiation capability of Argonne's HVEM-Tandem User Facility has been employed to determine the effects of 1.5 MeV Kr{sup +} irradiation and 300 kV electron irradiation on the crystallization of as-deposited and of partially crystallized 40 nm thick films of CoSi{sub 2}. Ion fluxes ranged from 8.5 {times} 10{sup 14} to 6.8 {times} 10{sup 15} m{sup {minus}2}s{sup {minus}1} for which beam heating effects may be neglected. The maximum electron flux at 300 kV was 0.8 {times} 10{sup 23} m{sup {minus}2}s{sup {minus}1}. The maximum temperature at which crystalline CoSi{sub 2} is amorphized by the ion irradiation of flux = 6.8 {times} 10{sup 15} m{sup {minus}2}s{sup {minus}1} is between 250 and 280 K. At higher temperatures amorphous material crystallizes by growth of any preexisting crystals and by classical nucleation and growth, with radial growth rates which are proportional to ion flux. The average degree of transformation per ion is 4 {times} 10{sup {minus}26} m{sup 3} per ion. Thermally induced crystallization of as-deposited films occurs above approximately 420 K. For ion doses at least as low as 3.4 {times} 10{sup 16} m{sup {minus}2} ion irradiation at 300 K promotes thermal crystallization at 450 K, by virtue of enhanced apparant nucleation …

Structural system identification methods are analytical techniques for reconciling test data with analytical models. The response data frequently used to compare a finite element model and test data are the eigenvalues of the system. However, eigenvalues alone cannot assure an adequate model. Eigenvectors also provide valuable information for the process of updating finite element models. For large order, complex finite element models, ad-hoc procedures have often proven inadequate for model parameter updating. Therefore, parameter estimation techniques such as Bayes estimation or mathematical programming have been applied. Mathematical programming techniques can be use for parameter estimation allowing a very general definition of the objective function and constraints. This paper will present the application of mathematical programming techniques of parameter estimation to the updating of a finite element model of an electronic package. The following topics will be discussed in the paper. The mathematical programming formulation of the parameter estimation problem, which uses both eigenvalue and eigenvector response data. The software implementation of this technique. The application of this methodology to the estimation of parameters of an electronics package model.

Microwave pulses have been injected from a free electron-laser (FEL) into the Microwave Tokamak Experiment (MTX) at up to 0.2 GW at 140 GHz in short pulses (10-ns duration) with O-mode polarization. The power transmitted through the plasma was measured in a first experimental study of high power pulse propagation in the plasma; no nonlinear effects were found at this power level. Calculations indicate that nonlinear effects may be found at the higher power densities expected in future experiments. 9 refs., 2 figs.

Verification of compliance with the provisions of the treaty on Conventional Forces-Europe (CFE) is subject to inspection quotas of various kinds. Thus the decision to carry out a specific inspection or verification activity must be prudently made. This decision process is outlined, and means for conserving quotas'' are suggested. 4 refs., 1 fig.

The SCDAP/RELAP5 code has been extended to calculate the core melt progression and fission product transport that may occur in non-LWR reactors during severe accidents. The code's approach of connecting together according to user instructions all of the parts that constitute a reactor system give the code the capability to model a wide range of reactor designs. The models added to the code for analyses of non-LWR reactors include: (a) oxidation and melt progression in cores with U-Al based fuel elements, (b) movement of liquefied material from its original place in the core to other parts of the reactor systems, such as the outlet piping, (c) fission product release from U-Al based fuel and zinc release from aluminum, and (d) fission product release from a pool of molten core material. 9 refs., 5 figs.

Edge magnetic and electrostatic fluctuations are measured in the Madison Symmetric Torus (MST) reversed field pinch. At low frequency (<25 kHz), the mode number spectra of magnetic fluctuations agree very well with theoretical prediction for nonlinearly saturated tearing fluctuations resonant in the core. At high frequency (50 kHz to 100 kHz) the magnetic spectra broaden and the modes become resonant in the reversal region. Nonlinear phenomena are under experimental investigation. The low frequency fluctuations phase-lock together to produce a rotating localized disturbance. Bi-spectral analysis in frequency also reveals nonlinear three-wave mode-coupling at low frequency. Electrostatic fluctuations are substantial and do not appear to obey a Boltzmann relation (i.e. e{tilde {phi}}/kT{sub e} > {tilde p}{sub e}/p{sub e} where {tilde {phi}} and {tilde p}{sub e} are the fluctuating potential and pressure, respectively). From measurements of the fluctuating density, temperature, and potential we infer that the electrostatic fluctuation induced transport of particles and energy can be substantial. 13 refs., 11 figs.

Global confinement measured in the first six months of MST full design operation is summarized. Central electron temperature and enhancement of resistivity over the Z = 1 Spitzer value are similar to other RFP experiments for the same value of I/N. As in several other RFP experiments, energy confinement time and poloidal beta are found to decrease with increasing plasma current, with maximum values of {tau}{sub E} {approximately} 1 ms and {beta}{sub p} {approximately} 10%. Particle transport may be approximated with a diffusion coefficient D {approximately} 40 m{sup 2}/s for a discharge studied with a 1-d particle-neutral code. A more elaborate code, incorporating heat and impurity transport, indicates an increase of Z{sub eff} with I/N. This code also reveals that the toroidal magnetic field decays resistively between discrete dynamo events, at the rate given by the measured global resistivity. Edge suprathermal electrons are observed as on other RFPs, with temperatures comparable to the central electron temperature and carrying a current density at least 15% of the total measured with an insertable magnetic coil array. Radial magnetic profiles measured with this array may be matched with a Modified Polynomial Function Model equilibrium for a value of {beta}{sub p} which is a …

A rapid, inexpensive trace multi-element analysis of reactor moderator heavy water is described. Samples were analyzed for copper, silver, gold, and mercury at the low ppb level using Differential Pulse Stripping Voltametry (DPSV). These ions are kept below 25 ppb to avoid possible vessel corrosion. A high concentration of aluminum and iron in the samples prevented analysis by ICP spectroscopy. The DPSV method also avoided volatizing highly tritiated samples. Differential Pulse Stripping Voltametry is a commonly used electroanalytical technique for determining trace levels of metals in aqueous solutions. However, application of this method for routine analytical support in a plant laboratory environment was limited due to the method's sensitivity to interferences. This paper describes a DPSV method which is rugged enough to be used for routine analytical support and addresses method interferences.

A rapid, inexpensive trace multi-element analysis of reactor moderator heavy water is described. Samples were analyzed for copper, silver, gold, and mercury at the low ppb level using Differential Pulse Stripping Voltametry (DPSV). These ions are kept below 25 ppb to avoid possible vessel corrosion. A high concentration of aluminum and iron in the samples prevented analysis by ICP spectroscopy. The DPSV method also avoided volatizing highly tritiated samples. Differential Pulse Stripping Voltametry is a commonly used electroanalytical technique for determining trace levels of metals in aqueous solutions. However, application of this method for routine analytical support in a plant laboratory environment was limited due to the method`s sensitivity to interferences. This paper describes a DPSV method which is rugged enough to be used for routine analytical support and addresses method interferences.

Both silver catalyzed and direct electrochemical oxidation of organic species are examined in analytical detail. This paper describes the mechanisms, reaction rates, products, intermediates, capabilities, limitations, and optimal reaction conditions of the electrochemical destruction of organic waste. A small bench-top electrocell being tested for the treatment of small quantities of laboratory waste is described. The 200-mL electrochemical cell used has a processing capacity of 50 mL per day, and can treat both radioactive and nonradioactive waste. In the silver catalyzed process, Ag(I) is electrochemically oxidized to Ag(II), which attacks organic species such as tributylphosphate (TBP), tetraphenylborate (TPB), and benzene. In direct electrochemical oxidation, the organic species are destroyed at the surface of the working electrode without the use of silver as an electron transfer agent. This paper focuses on the destruction of tributylphosphate (TBP), although several organic species have been destroyed using this process. The organic species are converted to carbon dioxide, water, and inorganic acids.

Both silver catalyzed and direct electrochemical oxidation of organic species are examined in analytical detail. This paper describes the mechanisms, reaction rates, products, intermediates, capabilities, limitations, and optimal reaction conditions of the electrochemical destruction of organic waste. A small bench-top electrocell being tested for the treatment of small quantities of laboratory waste is described. The 200-mL electrochemical cell used has a processing capacity of 50 mL per day, and can treat both radioactive and nonradioactive waste. In the silver catalyzed process, Ag(I) is electrochemically oxidized to Ag(II), which attacks organic species such as tributylphosphate (TBP), tetraphenylborate (TPB), and benzene. In direct electrochemical oxidation, the organic species are destroyed at the surface of the working electrode without the use of silver as an electron transfer agent. This paper focuses on the destruction of tributylphosphate (TBP), although several organic species have been destroyed using this process. The organic species are converted to carbon dioxide, water, and inorganic acids.

Silver catalyzed electrochemical oxidation of organic species is examined in analytical detail. This paper describes the mechanisms, reactions rates, products, intermediates, capabilities, limitations, and optimal reaction conditions of the electrochemical destruction of organic waste. A small bench-top electrocell being tested for the treatment of small quantity laboratory waste is described. The 200 mL electrochemical cell used has a processing capacity of 50 mL per day, and can treat both radioactive and non-radioactive waste. In the silver catalyzed process, Ag(I) is electrochemically oxidized to Ag(II) which attacks organic species such as tributylphosphate (TBP), tetraphenylborate (TPB), and benzene {sup 1,2}. This paper focuses on the destruction of tributylphosphate (TBP) although several organic species have been destroyed using this process. The organic species are converted to carbon dioxide, water, and inorganic acids. The process has the potential for RCRA (Resource Conservation and Recovery Act) waste treatment as well as disposal of large amounts of radioactive organic waste.

The Scalable Coherent Interface (IEEE P1596) is establishing an interface standard for very high performance multiprocessors, supporting a cache-coherent-memory model scalable to systems with up to 64K nodes. This Scalable Coherent Interface (SCI) will supply a peak bandwidth per node of 1 GigaByte/second. The SCI standard should facilitate assembly of processor, memory, I/O and bus bridge cards from multiple vendors into massively parallel systems with throughput far above what is possible today. The SCI standard encompasses two levels of interface, a physical level and a logical level. The physical level specifies electrical, mechanical and thermal characteristics of connectors and cards that meet the standard. The logical level describes the address space, data transfer protocols, cache coherence mechanisms, synchronization primitives and error recovery. In this paper we address logical level issues such as packet formats, packet transmission, transaction handshake, flow control, and cache coherence. 11 refs., 10 figs.

MAssive Compact Halo Objects such as brown dwarfs, Jupiters, and black holes are prime candidates to comprise the dark halo of our galaxy. Paczynski noted that these objects (dubbed MACHOs) can be detected via gravitational microlensing of stars in the Magellanic Clouds with the caveat that only about one in 10{sup 6} stars will be lensed at any given time. Our group is currently involved in constructing a dedicated observing system at the Mount Stromlo Observatory in Australia. We will use a refurbished 1.27 meter telescope and an innovative two-color CCD camera with 3.4 {times} 10{sup 7} pixels to monitor 10{sup 6} {minus} 10{sup 7} stars in the Magellanic Clouds. During the first year of operation (1991--1992), we hope to detect (or rule out) objects in the mass range 0.001M{sub {circle dot}} {le} M {le} 0.1M{sub {circle dot}}, and after five years, we hope to have covered the range 10{sup {minus}6}M{sub {circle dot}} < M {approx lt} 100M{sub {circle dot}}. 4 refs.

The field of ion acceleration to higher energies has grown rapidly in the last years. Many new facilities as well as substantial upgrades of existing facilities have extended the mass and energy range of available beams. Perhaps more significant for the long-term development of the field has been the expansion in the applications of these beams, and the building of facilities dedicated to areas outside of nuclear physics. This review will cover many of these new developments. Emphasis will be placed on accelerators with final energies above 50 MeV/amu. Facilities such as superconducting cyclotrons and storage rings are adequately covered in other review papers, and so will not be covered here.

The newest particle accelerators are almost always built for extending the frontiers of research, at the cutting edge of science and technology. Once these machines are operating and these technologies mature, new applications are always found, many of which touch our lives in profound ways. The evolution of accelerator technologies will be discussed, with descriptions of accelerator types and characteristics. The wide range of applications of accelerators will be discussed, in fields such as nuclear science, medicine, astrophysics and space-sciences, power generation, airport security, materials processing and microcircuit fabrication. 13 figs.

The x-ray absorption spectroscopy (XAS) had been an essential tool to gather spectroscopic information about atomic energy level structure in the early decades of this century. It has also played an important role in the discovery and systematization of rare-earth elements. The discovery of synchrotron radiation in 1952, and later the availability of broadly tunable synchrotron based x-ray sources have revitalized this technique since the 1970's. The correct interpretation of the oscillatory structure in the x-ray absorption cross-section above the absorption edge by Sayers et. al. has transformed XAS from a spectroscopic tool to a structural technique. EXAFS (Extended X-ray Absorption Fine Structure) yields information about the interatomic distances, near neighbor coordination numbers, and lattice dynamics. An excellent description of the principles and data analysis techniques of EXAFS is given by Teo. XANES (X-ray Absorption Near Edge Structure), on the other hand, gives information about the valence state, energy bandwidth and bond angles. Today, there are about 50 experimental stations in various synchrotrons around the world dedicated to collecting x-ray absorption data from the bulk and surfaces of solids and liquids. In this chapter, we will give the basic principles of XAS, explain the information content of essentially two different …

Sandia National Laboratories is the lead laboratory for the United States Department of Energy's program to develop, build, and test advanced solar concentrators that are low in cost, have high performance, and demonstrate a long lifetime. The principal focus of DOE's concentrator program is on the development of heliostats for central receiver power plants and point focus parabolic dishes for use with a 25-kWe Stirling engine. The status and future plans of DOE's program in each area are reviewed. 29 refs., 7 figs.

A high-intensity, plasma-sputter, negative ion source, which utilizes multi-cusp, magnetic-field, plasma-confinement techniques, has been designed at the Oak Ridge National Laboratory (ORNL). The source is an axial-geometry version of the radial-geometry source which has demonstrated pulsed-mode peak intensity levels of several mA for a wide spectrum of heavy negative ion species. The mechanical design features include provisions for fast interchange of sputter samples, ease of maintenance, direct cooling of the discharge chamber, and the use of easily replaced coaxial LaB{sub 6} cathodes. 13 refs., 3 figs., 1 tab.

The principal negative ion formation processes will be briefly reviewed. Primary emphasis will be placed on the more efficient and universal processes of charge transfer and secondary ion formation through non-thermodynamic surface ionization. 86 refs., 20 figs.

Computational studies of the principal electron capture and loss processes which take place during interactions between a multi-electron projectile and a target in various degrees of ionization have been initiated. These studies are designed to determine the feasibility of a plasma stripper as a possible alternative to the gaseous and foil strippers which are commonly used to enhance the charge states of energetic ion beams. The idea is based on the knowledge that the stopping powers (energy loss per unit path length) are greater for a plasma than a gaseous stripper at equivalent line densities, and the number of electron channels available for capture by the projectile are reduced when the target is highly ionized. Preliminary results of attempts to evaluate the merits of a plasma for this applications are given in this report. 11 refs., 3 figs.

Experiment E769 at Fermilab obtained charm hadroproduction data during the 1987-88 Fixed Target running period with a 250 GeV hadron beam incident on thin target foils of Be, Al, Cu, and W. From an analysis of 25% of the recorded 400M trigger sample we have explored the Feynman x, p{sub t}{sup 2} and the atomic number dependence of charm quark production using samples of D{sup +} and D{sup 0} mesons. 7 refs., 4 figs.

This paper is a presentation to the International Professional Communication Conference on International English. Presidence is taken from the Royal Society of London in 1667 to purify and simplify the English language. Because English has become the most spoken language in the world, the case in herein made to make it plainer and more easily learned. Technical communications is stressed. (FSD).