A Lawrence Berkeley National Laboratory (Berkeley Lab) team drawing its members from the Materials Sciences Division (MSD), the Center for Beam Physics in the Accelerator and Fusion Research Division, and the Advanced Light Source (ALS) has succeeded in generating 300-femtosecond pulses of synchrotron radiation at the ALS synchrotron radiation machine. Though this ''proof-of-principle'' experiment made use of visible light on a borrowed beamline, the laser ''time-slicing'' technique at the heart of the demonstration will soon be applied in a new bend-magnet beamline designed explicitly for the production of femtosecond pulses of X-rays to study long-range and local order in condensed matter with ultrafast time resolution. An undulator beamline based on the same technique has been proposed that will dramatically increase the flux and brightness.

Electro-osmosis, a coupled-flow phenomenon in which an applied electrical potential gradient drives water flow, may be used to induce water flow through fine-grained sediments. We plan to use this technology to remediate chlorinated solvent-contaminated clayey zones at the LLNL site. The electro-osmotic conductivity (k{sub e}) determined from bench-top studies for a core extracted from a sediment zone 36.4-36.6 m below surface was initially 7.37 x 10{sup -10} m{sup 2}/s-V, decreasing to 3.44 x 10{sup -10} m{sup 2}/s-V, after electro-osmotically transporting 0.70 pore volumes of water through it (195 ml). Hydraulic conductivity (k{sub h}) of the same core was initially measured to be 5.00 x 10{sup -10} m/s, decreasing to 4.08 x 10{sup -10} m/s at the end of processing. This decline in permeability is likely due to formation of a chemical precipitation zone within the core. Water splitting products and ions electromigrate and precipitate within the core; H{sup +} and metal cations migrate toward the cathode, and OH{sup -} from the cathode moves toward the anode. We are now exploring how to minimize this effect using pH control. The significance of this technology is that for this core, a 3 V/cm voltage gradient produced an initial effective hydraulic conductivity of …

Hardware performance counters are CPU registers that count data loads and stores, cache misses, and other events. Counter data can help programmers understand software performance. Although CPUs typically have multiple counters, each can monitor only one type of event at a time, and some counters can monitor only certain events. Therefore, some CPUs cannot concurrently monitor interesting combinations of events. Software multiplexing partly overcomes this limitation by using time sharing to monitor multiple events on one counter. However, counter multiplexing is harder to implement for multithreaded programs than for single-threaded ones because of certain difficulties in managing the length of the time slices. This paper describes a software library called MPX that overcomes these difficulties. MPX allows applications to gather hardware counter data concurrently for any combination of countable events. MPX data are typically within a few percent of counts recorded without multiplexing.

The Plutonium Immobilization Project is currently undertaking formulation and process development to demonstrate the immobilization of surplus plutonium in a titanate-based ceramic. These ceramic forms will be encapsulated within canisters containing high level waste glass for geologic disposal. Process development work is being conducted with sub-scale, process prototypic equipment. Final validation of the process will be done using actual plutonium material and functionally prototypic equipment within a glovebox. Due to the radioactive nature of the material, remote material handling is necessary to reduce the radiation exposure to the operators. A remote operated Material Transfer System to interface with process equipment has been developed.

It is shown that high rate extrusion is a viable production process for obtaining desirable microstructures and mechanical properties in ultrahigh carbon steels (UHCSs). The coefficient of friction for extrusion was determined for the UHCSs as well as five other materials and shown to be a function of stress--decreasing with increasing stress. The extruded UHCSs deform by a diffusion-controlled dislocation creep process. Stacking fault energies have been calculated from the extrusion data and observed to decrease with increasing concentrations of silicon, aluminum and chromium. Microstructures are either ultrafine pearlite when extruded above the eutectoid temperature or ultrafine spheroidite when extruded below the eutectoid temperature. The resulting strength--ductility properties are shown to be superior to those obtained in high-strength low alloy steels.

The application of coatings over large areas can be approached through the use of large deposition sources. A versatile alternative, e.g. to long rectangular magnetrons, are linear arrays of circular planar magnetrons to process coatings over wide path lengths. They investigate the feasibility of using a linear array of 76 mm diameter magnetron sources operated in the rf mode to deposit oxide target materials across a path in excess of 0.7 m wide. Specific results are given for the case of a 2 {micro}m thick, alumina coating.

A approach for quantifying meteorological uncertainty is via development of an ensemble of forecasts from slightly perturbed initial conditions (Sivillo et al., 1997) to predict the time evolution of the probability density function of atmospheric variables (Mullen and Baurnhefner, 1994). We create an ensemble of forecasts by varying the initial (and boundary) conditions for the COAMPS meteorological model. The variations in the initial conditions must be consistent with analysis error. Optimally, the range of initial conditions would encompass the ''true'' atmospheric state, but which is never actually known. Our method for creating varying initial conditions is to use different global data sets to derive the necessary data. We use two models from the National Weather Service (the AVN and ETA models) and one from the Navy (the NOGAPS model). In addition to those data sets we perturb the data from those models, using a normally distributed random number at each grid point in the COAMPS model. We perturb the (u,v) wind components, the temperature and the moisture. The size of the perturbation is determined by the variability within that variable field. The forecasts are run for 48 hours. We then use the output from the COAMPS model to drive a …

We have demonstrated a non-contact method of concentrating and mixing particles in a plastic microfluidic chamber employing acoustic radiation pressure. A flaw cell package has also been designed that integrates liquid sample interconnects, electrical contacts and a removable sample chamber. Experiments were performed on 1, 3, 6, and 10 {micro}m polystyrene beads. Increased antibody binding to a solid-phase substrate was observed in the presence of acoustic mixing due to improve mass transport.

This article discusses inter- and intramolecular experimental and calculated equilibrium isotope effects.

Ab initio DFT electronic structure calculations involve an iterative process to solve the Kohn-Sham equations for an Hamiltonian depending on the electronic density. We discretize these equations on a grid by finite differences. Trial eigenfunctions are improved at each step of the algorithm using multigrid techniques to efficiently reduce the error at all length scale, until self-consistency is achieved. In this paper we focus on an iterative eigensolver based on the idea of inexact inverse iteration, using multigrid as a preconditioner. We also discuss how this technique can be used for electrons described by general non-orthogonal wave functions, and how that leads to a linear scaling with the system size for the computational cost of the most expensive parts of the algorithm.

In this article the authors concisely present several modern strategies that are applicable to drift-dominated carrier transport in higher-order deterministic models such as the drift-diffusion, hydrodynamic, and quantum hydrodynamic systems. The approaches include extensions of upwind and artificial dissipation schemes, generalization of the traditional Scharfetter-Gummel approach, Petrov-Galerkin and streamline-upwind Petrov Galerkin (SUPG), entropy variables, transformations, least-squares mixed methods and other stabilized Galerkin schemes such as Galerkin least squares and discontinuous Galerkin schemes. The treatment is representative rather than an exhaustive review and several schemes are mentioned only briefly with appropriate reference to the literature. Some of the methods have been applied to the semiconductor device problem while others are still in the early stages of development for this class of applications. They have included numerical examples from the recent research tests with some of the methods. A second aspect of the work deals with algorithms that employ unstructured grids in conjunction with adaptive refinement strategies. The full benefits of such approaches have not yet been developed in this application area and they emphasize the need for further work on analysis, data structures and software to support adaptivity. Finally, they briefly consider some aspects of software frameworks. These include dial-an-operator approaches …

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An integrated approach, including a continuum theory of sintering and mesostructure evolution analysis, is used for the solution of the problem of bi-layered structure sintering. Two types of bi-layered structures are considered: layers of the same material different by initial porosity, and layers of two different materials. The effective sintering stress and the normalized bulk modulus for the bi-layer powder sintering are derived based on mesoscale simulations. The combined effect of the layers' porosity and differences in sintering rate on shrinkage and warpage is studied for both sintering on a rigid substrate and free sintering.

The authors report a measurement of the diffractive structure function of the antiproton for dijet events produced in association with a leading antiproton in {anti p}p collisions at {radical}(s) = 1800 GeV. Comparing their results with expectations based on parton densities extracted by the H1 Collaboration from diffractive deep inelastic scattering at the DESY ep collider HERA, the authors find a severe breakdown of QCD factorization.

The topological local cluster (or Schlaefli cluster) concept of Marians and Hobbs is used to detect topologically crystalline regions in models of disordered tetrahedral semiconductors. The authors present simple algorithms for detecting both Wells-type shortest circuits and O'Keeffe-type rings, which can be used to delineate alternative forms of the Schlaefli cluster in models.

Low cost SMP (Symmetric Multi-Processor) systems provide substantial CPU and I/O capacity. These features together with the ease of system integration make them an attractive and cost effective solution for a number of real-time applications in event selection. In ATLAS the authors consider them as intelligent input buffers (active ROB complex), as event flow supervisors or as powerful processing nodes. Measurements of the performance of one off-the-shelf commercial 4-processor PC with two PCI buses, equipped with commercial FPGA based data source cards (microEnable) and running commercial software are presented and mapped on such applications together with a long-term program of work. The SMP systems may be considered as an important building block in future data acquisition systems.

The optical gain spectra for GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of the lasing threshold current density of GaInNAs/GaAs quantum well structures.

The US Department of Energy (DOE) Idaho National Engineering and Environmental Laboratory (INEEL) has embraced mobile wireless technology to help the disposition of hazardous and mixed radiological waste. The following paper describes one application the INEEL developed to increase the data accuracy and near-real time reporting requirements for waste management. With the continuous operational demands at the ''site'', it was difficult to sustain an accurate, up-to-date database required for regulatory compliance audits and reporting. Incorporating wireless mobile technology, the INEEL was able to increase the accuracy while reducing the data delay times previously encountered. Installation issues prolonged the project along with obstacles encountered with operations personnel. However, the success of this project was found in persistence and management support as well as the technology itself. Future wireless, mobile computing will continue at the INEEL for years to come based on a successful project that was able to integrate new technology to an existing waste management system with proven, increased data accuracy.

The switching and memory retention time has been measured in 50 {micro}m gatelength pseudo-non-volatile memory MOSFETS containing, protonated 40 nm gate oxides. Times of the order of 3.3 seconds are observed for fields of 3 MV cm{sup {minus}1}. The retention time with protons placed either at the gate oxide/substrate or gate oxide/gate electrode interfaces is found to better than 96{percent} after 5,000 seconds. Measurement of the time dependence of the source-drain current during switching provides clear evidence for the presence of dispersive proton transport through the gate oxide.

The authors report on searches for leptoquarks using approximately 100 pb {sup -1} of data collected by CDF and DO during Run I at the Tevatron. They also present searches for resonantly-produced leptoquarks that arise in technicolor models. Prospects for future leptoquark searches using Run II data are also discussed.

The Department of Energy (DOE) has given the Spallation Neutron Source (SNS) project approval to begin Title I design of the proposed facility to be built at Oak Ridge National Laboratory (ORNL) and construction is scheduled to commence in FY01 . The SNS initially will consist of an accelerator system capable of delivering an {approximately}0.5 microsecond pulse of 1 GeV protons, at a 60 Hz frequency, with 1 MW of beam power, into a single target station. The SNS will eventually be upgraded to a 2 MW facility with two target stations (a 60 Hz station and a 10 Hz station). The radiation transport analysis, which includes the neutronic, shielding, activation, and safety analyses, is critical to the design of an intense high-energy accelerator facility like the proposed SNS, and the Monte Carlo method is the cornerstone of the radiation transport analyses.

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A new frontier in physics originated with programs at two Brookhaven National Laboratory facilities--the Cosmotron and the Alternating Gradient Synchrotron. The development of this frontier over a half century is described, as it turned from conventional nuclear physics to the hypernuclei and the study of strange matter.

We present beam-beam simulation results from a strong-strong gaussian code for separated beams for the LHC. We focus on the possible detrimental effects of the beam-beam interaction in cases when the beams are: (1) periodically swept about each other, and (2) brought into collision from separated orbits. For 10{sup 5}-turn runs we do not see significant emittance blowup for nominal bunch intensities, although there is significant blowup at intensities 10 times the nominal value.