The complexity of large-scale scientific simulations often necessitates the combined use of multiple software packages developed by different groups in areas such as adaptive mesh manipulations, scalable algebraic solvers, and optimization. Historically, these packages have been combined by using custom code. This practice inhibits experimentation with and comparison of multiple tools that provide similar functionality through different implementations. The ALICE project, a collaborative effort among researchers at Argonne National Laboratory, is exploring the use of component-based software engineering to provide better interoperability among numerical toolkits. They discuss some initial experiences in developing an infrastructure and interfaces for high-performance numerical computing.

Single crystals of KH{sub 2}PO{sub 4} (KDP) and (D{sub x}H{sub 1-x}){sub 2}PO{sub 4} (DKDP) will be used for frequency conversion and as part of a large aperture optical switch in the proposed National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL). These crystals must have good optical properties and high laser damage thresholds. Currently these crystals have a lower laser damage threshold than other optical materials in the laser chain which has forced designers to limit the output fluence of the NIF in order to avoid damaging the crystals. Furthermore, while more efficient frequency conversion schemes are being explored both theoretically and experimentally, the advantages of these schemes can not be fully realized unless the damage thresholds of the conversion crystals are increased. Over the past decade, LLNL has generated an extensive data base on the laser damage in KDP and DKDP crystals both at the first and third harmonics of Nd-YAG. While the damage thresholds of these crystals have increased over this time period due, in part, to better filtration of the growth solution, the damage thresholds of the best crystals are still far below what is expected from theoretical limits calculated from the band structure of …

Using a subset of data collected in the 1996-97 fixed target run at Fermilab, the authors report the first preliminary measurement on the direct-CP violation from the KTeV experiment. The result is, e{prime}/e = (28.0-4.1) x 10{sup {minus}4}, nearly 7 standard deviations above zero obtained by a blind analysis. This establishes the long-sought direct-CP violation effect in the two-pion system of neutral kaon decays. The experimental technique, data analysis and systematic checks for this measurement are discussed and the comparison with other measurements is also presented.

Since the original observations by Duncumb in 1962, a number of studies have been conducted on the effects of electron channel on characteristic x-ray emission and microanalysis. Most of the recent studies have concentrated upon using the phenomenon to perform site specific distributions of impurity elements in ordered compounds using the ALCHEMI methodology. Very few studies have attempted to accurately measure the effect as a function of orientation and compare these results to theories. In this study, two dimensional high angular resolution studies of channeling enhance x-ray emission were performed and herein the results are compared to theoretical calculations of Allen et al. All experimental measurements presented here were conducted on a Philips EM 420T analytical electron microscope. The instrument was operated in the TEM mode, at 120 kV using an LaB6 electron source. The characteristic x-ray emission was measured using an EDAX ultra thin window Si(Li) detector having a FWHM of {approximately}145 eV at Mn Km Nominal probe sizes used during the study were 200-500 nm with beam convergence half angle defined by the Condenser apertures. Control of the relative orientation of the incident probe was accomplished via direct computer control of the beam tilt coils, after the specimen …

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A chemically bonded magnesium potassium phosphate ceramic has been developed by an acid-base reaction at room temperature, for use in stabilizing U.S. Department of Energy low-level mixed waste streams that include hazardous metals and low-level radioactive elements. Using this ceramic, we solidified, in monolithic waste forms, low-level mixed waste streams containing various levels of PbCl{sub 2} and PbCO{sub 3}. These final waste forms were evaluated for their land disposal suitability. The results showed low open porosity (1.48-4.61 vol.%); hence, low permeability, and higher compression strengths (4310-6734 psi) that were one order of magnitude above that required. The level of lead in the leachate following the Toxicity Characteristic Leaching Procedure test was reduced from 50,000 to <0.1 ppm. Leachability indexes from the long-term leaching test (ANS 16.1 test) were between 11.9 and 13.6. This excellent lead retention is due to its chemical fixation as insoluble lead phosphate and to physical encapsulation by the phosphate matrix.

If the strange quark matter hypothesis is true, then a new class of white dwarfs can exist whose nuclear material in their deep interiors can have a density as high as the neutron drip density, a few hundred times the density in maximum-mass white dwarfs and 4 {times} 10{sup 4} the density in dwarfs of typical mass, M {approximately} 0.6M{sub {circle_dot}}. Their masses fall in the approximate range 10{sup {minus}4} to 1M{sub {circle_dot}}. They are stable against acoustical modes of vibration. A strange quark core stabilizes these stars, which otherwise would have central densities that would place them in the unstable region of the sequence between white dwarfs and neutron stars.

This research project demonstrated the effectiveness of using evolutionary software techniques in the development of path-planning algorithms and control programs for mobile vehicles in radioactive environments. The goal was to take maximum advantage of the programmer's intelligence by tasking the programmer with encoding the measures of success for a path-planning algorithm, rather than developing the path-planning algorithms themselves. Evolutionary software development techniques could then be used to develop algorithms most suitable to the particular environments of interest. The measures of path-planning success were encoded in the form of a fitness function for an evolutionary software development engine. The task for the evolutionary software development engine was to evaluate the performance of individual algorithms, select the best performers for the population based on the fitness function, and breed them to evolve the next generation of algorithms. The process continued for a set number of generations or until the algorithm converged to an optimal solution. The task environment was the navigation of a rover from an initial location to a goal, then to a processing point, in an environment containing physical and radioactive obstacles. Genetic algorithms were developed for a variety of environmental configurations. Algorithms were simple and non-robust strings of behaviors, …

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The accumulation of ion implantation damage in Al{sub x}Ga{sub 1{minus}x}As/GaAs heterostructures (0 {le} x {le} 0.85) at 77 K has been investigated by using a combination of RBS (at 77 K and 293 K) and TEM (at 293 K). Recovery, as seen by a decrease in the channeling yield, occurs on warming to room temperature unless the material has been driven amorphous or x {ge} 0.85. Depending on the implantation condition, the recovered structure consists of either planar defects or dislocation loops. Planar defects were also observed in alloys with x = 0.85, although they were confined to a narrow band that separated the amorphous from the crystalline material. By implanting with ions of different energy it was shown that amorphization can initiate within the layer away from the interfaces, showing that interfaces are not needed for amorphization. Implantations with 500 keV Krions were performed at 50 K in-situ in the Intermediate-Voltage Electron Microscope--Accelerator facility at Argonne National Laboratory. Planar defects were produced on warmup, showing that they are not necessary for amorphization. We propose that amorphization initiates because of an accumulation of damage and that the dependence of the amorphization dose on Al content is related to differences in …

In early 1993. Argonne National Laboratory (ANL) initiated a major R and D effort to develop bipolar Li-Al/LiCl-LiBr-KBr/FeS{sub 2} batteries for electric vehicles, targeting the USABC Long-Term Goals. Significant advancements were achieved in the areas of (i) chemical purity, (ii) electrode and electrolyte additives, and (iii) peripheral seals. It was determined that key chemical constituents contained undesirable impurities. ANL developed new chemical processes for preparing Li{sub 2}S, FeS, and CoS{sub 2} that were >98.5% pure. We evaluated a large variety of electrode and electrolyte additives for reducing cell area specific impedance (ASI). Candidate positive electrode additives offered increased electronic conductivity, enhanced reaction kinetics, and/or improved porous electrode morphology. CoS{sub 2}, CuFeS{sub 2}, MgO, and graphite (fibers) were identified as the most beneficial impedance-reducing positive electrode additives. Although electronically conductive carbon and graphite additives produced measurable ASI reductions in the negative electrode, they degraded its structural integrity and were deemed impractical. Lil and LiF were identified as beneficial electrolyte additives, that enhance positive electrode kinetics. ANL refined its baseline metal/ceramic peripheral seal and increased its strength by a factor of three (achieving a safety factor >10). In parallel, ANL developed a high-strength advanced metal/ceramic seal that offers appreciable cost reductions.

When a noble gas element such as Xe is implanted in an fcc metal matrix such as Al at room temperature, a fine dispersion of precipitates forms. The precipitates are elementary fcc crystals up to diameters of several nanometers (for Xe in Al, 8-10 rim), above which they are non-crystalline. The precipitates exhibit a cube-on-cube orientation relation with the matrices and have lattice parameters which are much larger than those of the matrices (a{sub Xe} = 1.5a{sub Al}). Thus the interphase interfaces are incommensurate though the lattices are isotactic. The precipitates assume the shape of matrix cavities; for an Al matrix, at equilibrium this is a cuboctahedron, a {r_brace}111{l_brace} octahedron truncated at the corners on {l_brace}100{r_brace}. Fig. 1 is a sketch of a dispersion of such cuboctahedra, viewed approximately along a {l_angle}110{r_angle}. For this study specimens were prepared in the HVEM-Tandem Facility at Argonne National Laboratory by implanting 35 keV Xe to a dose of 4x10{sup 19} m{sup {minus}2} into well-annealed 5N Al discs which had been thinned by jet electropolishing. The range of the implant is approximately 25 nm. Specimens were examined at high resolution in the JEOL ARM-1000 high voltage electron microscope (HVEM) at the High Resolution Beam …

The US Department of Energy (DOE) has developed a site characterization plan (SCP) to collect detailed information on geology, geohydrology, geochemistry, geoengineering, hydrology, climate, and meteorology (collectively referred to as ``geologic information``) of the Yucca Mountain site. This information will be used to determine if a mined geologic disposal system (MGDS) capable of isolating high-level radioactive waste without adverse effects to public health and safety over 10,000 years, as required by regulations 40 CFR Part 191 and 10 CFR Part 60, could be constructed at the Yucca Mountain site. Forecasts of future climates conditions for the Yucca Mountain area will be based on both empirical and numerical techniques. The empirical modeling is based on the assumption that future climate change will follow past patterns. In this approach, paleclimate records will be analyzed to estimate the nature, timing, and probability of occurrence of certain climate states such as glacials and interglacials over the next 10,000 years. For a given state, key climate parameters such as precipitation and temperature will be assumed to be the same as determined from the paleoclimate data. The numerical approach, which is the primary focus of this paper, involves the numerical solution of basic equations associated with …

The scales that grow from oxidation often develop a convoluted morphology or interface pores. High thermal stresses can develop locally and are potentially detrimental to the scale or interface integrity. Finite element simulations are used to examine residual thermal stresses and strains that result when these deviations from a flat interface have formed, and the resulting geometry is subsequently cooled to room temperature. A variety of geometries will be considered for alumina scales on a FeCrAl substrate.

Argonne National Laboratory is currently developing a new reactor control system for the McClellan Nuclear Radiation Facility. This new control system not only provides the same functionality as the existing control system in terms of graphic displays of reactor process variables, data archival capability, and manual, automatic, pulse and square-wave modes of operation, but adds to the functionality of the previous control system by incorporating signal processing algorithms for the validation of sensors and automatic calibration and verification of control rod worth curves. With the inclusion of these automated features, the intent of this control system is not to replace the operator but to make the process of controlling the reactor easier and safer for the operator. For instance, an automatic control rod calibration method reduces the amount of time to calibrate control rods from days to minutes, increasing overall reactor utilization. The control rod calibration curve, determined using the automatic calibration system, can be validated anytime after the calibration, as long as the reactor power is between 50W and 500W. This is done by banking all of the rods simultaneously and comparing the tabulated rod worth curves with a reactivity computer estimate. As long as the deviation between the …

The observation of atomic-scale structures of grain boundaries (GBs) via axial illumination HREM has been largely restricted to tilt GBs, due to the requirement that the electron beam be parallel to a low-index zone axis on both sides of the interface. This condition can be fulfilled for all tilt GBs with disorientation about a low-index direction. The information obtained through HREM studies in many materials has brought important insights concerning the atomic-scale structure of such boundaries. However, it is well known that tilt GBs occupy only an infinitesimally small fraction of the 5-dimensional phase space which describes the macroscopic geometry of all GBs. Therefore, although tilt GBs are very important due to their low energy, it would be useful to also study twist GBs and general GBs that contain twist and tilt components.

Presented are the most recent jet fragmentation results from CDF: inclusive distributions of charged particle momenta and their k{sub T} in jets; average track multiplicities, as well as angular distributions of multiplicity flow, for a wide range of jet energies with E{sub T} from 40 to 300 GeV. The results are compared with Monte-Carlo and, when possible, analytical calculations performed in resumed perturbative QCD approximations (MLLA).

A major upgrade of the first ATLAS 10 GHz ECR ion source, which began operations in 1987, is in the planning and procurement phase. The new design will convert the old two-stage source into a single-stage source with an electron donor disk and high gradient magnetic field that preserves radial access for solid material feeds and pumping of the plasma chamber. The new magnetic field profile allows for the possibility of a second ECR zone at a frequency of 14 GHz. An open hexapole configuration, using a high energy-product Nd-Fe-B magnet material, having an inner diameter of 8.8 cm and pole gaps of 2.4 cm has been adopted. Models indicate that the field strengths at the chamber wall, 4 cm in radius, will be 9.3 kG along the magnet poles and 5.6 kG along the pole gaps. The individual magnet bars will be housed in austenitic stainless steel allowing the magnet housing within the aluminum plasma chamber to be used as a water channel for direct cooling of the magnets. Eight solenoid coils from the existing ECR will be enclosed in an iron yoke to produce the axial mirror. Based on a current of 500 A, the final model predicts …

Limitations on the use of petroleum-based diesel fuel in California could occur pursuant to the 1998 declaration by California's Air Resources Board (CARB) that the particulate matter component of diesel exhaust is a carcinogen, therefore a toxic air contaminant (TAC) subject to provisions of the state's Proposition 65. It is the declared intention of CARB not to ban or restrict diesel fuel, per se, at this time. Assuming no total ban, Argonne National Laboratory (ANL) explored two feasible ''mid-course'' strategies. (1) Increased penetration of natural gas and greater gasoline use in the transportation fuels market, to the extent that some compression-ignition (CI) applications revert to spark-ignition (SI) engines. (2) New specifications requiring diesel fuel reformulation based on exhaust products of individual diesel fuel constituents. Each of these alternatives results in some degree of (conventional) diesel displacement. In the first case, diesel fuel is assumed admissible for ignition assistance as a pilot fuel in natural gas (NG)-powered heavy-duty vehicles, and gasoline demand in California increases by 32.2 million liters per day overall, about 21 percent above projected 2010 baseline demand. Natural gas demand increases by 13.6 million diesel liter equivalents per day, about 7 percent above projected (total) consumption level. In …

NEUTRON NUCLEAR DATA THAT IS USED IN REACTOR DOSIMETRY INCLUDE THERMAL NEUTRON CROSS SECTIONS AND NEUTRON RESONANCE INTEGRALS, FISSION SPECTRUM AVERAGED CROSS SECTIONS FOR REACTIONS ON A TARGET NUCLEUS. NON-NEUTRON NUCLEAR DATA USED IN REACTOR DOSIMETRY INCLUDE ISOTOPIC COMPOSITIONS OF TARGET NUCLIDES AND RADIOACTIVE HALF-LIVES, GAMMA-RAY ENERGIES AND INTENSITIES OF REACTION PRODUCT NUCLIDES. ALL OF THESE DATA ARE PERIODICALLY EVALUATED AND RECOMMENDED VALUES ARE PROVIDED IN THE HANDBOOK OF CHEMISTRY AND PHYSICS. THE LATEST RECOMMENDED VALUES ARE DISCUSSED AND THEY ARE CONTRASTED WITH SOME EARLIER NUCLEAR DATA, WHICH WAS PROVIDED WITH NEUTRON DETECTOR FOILS.

A metallic waste form alloy that consists primarily of stainless steel and zirconium is being developed by Argonne National Laboratory to contain metallic waste constituents that are residual from an electrometallurgical treatment process for spent nuclear fuel. Ingots have been cast in an induction furnace in a hot cell using actual, leftover, irradiated, EBR-II cladding hulls treated in an electrorefiner. The as-cast ingots have been sampled using a core-drilling and an injection-casting technique. In turn, generated samples have been characterized using chemical analysis techniques and a scanning electron microscope equipped with energy dispersive and wavelength-dispersive spectrometers. As-cast ingots contain the predicted concentration levels of the various constituents, and most of the phases that develop are analogous to those for alloys generated using non-radioactive surrogates for the various fission products.

To better understand the vortex dynamics of coherent structures in turbulent and transitional boundary layers, we consider direct numerical simulation of the interaction between a flat-plateboundary-layer flow and an isolated hemispherical roughness element. Of principal interest is the evolution of hairpin vortices that form an interlacing pattern in the wake of the hemisphere, lift away from the wall, and are stretched by the shearing action of the boundary layer. Using animations of unsteady three-dimensional representations of this flow, produced by the vtk toolkit and enhanced to operate in a CAVE virtual environment, we identify and study several key features in the evolution of this complex vortex topology not previously observed in other visualization formats.

X-ray scattering measurements at 10 keV from multilayers having a period of 24.8 {angstrom} and consisting of 100 W/C bilayers are reported. Specular scans revealed first order reflectivities in the range 73.5% to 78.0% with bandpasses in the range of 1.5% to 1.7%. Total roughness (or interface grading) values deduced from fitting were in the range 2.5 to 3.0 for the last-to-grow surface of the W layers. Diffuse scattering measurements were made in a novel geometry that permitted investigation of in-plane momentum transfers up to 0.2 {angstrom}{sup {minus}1}. This is roughly an order of magnitude larger than is possible in conventional rocking scans. A power law dependence of the diffuse scattering after integration over a ''Brillioun zone'' is found. The exponent of this power law, 1.75, when interpreted using a logarithmic correlation function leads to a value of 1.0 {angstrom} for the correlated roughness.

Significant effort is presently focused on reducing the size and weight of power electronic modules. To achieve these goals in high-power capacitors, alternative materials and fabrication processes are needed. Thin film (<0.5 {micro}m) and bulk capacitors that use perovskite-based ferroelectric dielectrics are promising alternative technologies. Ferroelectrics possess high dielectric constants, thus offering substantial increases in volumetric capacitance. In thin film form, these materials display low loss and high breakdown strength. The unique properties of some of these materials, such as a nonlinear dielectric response or a high energy-storage capacity accompanying a phase change, can be exploited for power electronic capacitors. Prototype capacitors of two such materials, (Ba,Sr)TiO{sub 3} and PbZrO{sub 3}, have been fabricated in both thin film and bulk ceramic form. The influence of fabrication conditions on dielectric properties has been studied. Initial studies have demonstrated the viability of perovskite ferroelectrics for next-generation capacitor components.