This article reviews some recent materials analysis results using high-energy positron beams at Lawrence Livermore National Laboratory. We are combining positron lifetime and orbital electron momentum spectroscopic methods to provide electron number densities and electron momentum distributions around positron annihilation sites. Topics covered include: correlation of positron annihilation characteristics with structural and mechanical properties of bulk metallic glasses, compositional studies of embrittling features in nuclear reactor pressure vessel steel, pore characterization in Zeolites, and positron annihilation characteristics in alkali halides.

A solid-state modulator with very fast rise and fall times, pulse width agility, and multi-pulse burst and intra-pulse amplitude adjustment capability for use with high speed electron beam kickers has been designed and tested at LLNL. The modulator uses multiple solid-state modules stacked in an inductive-adder configuration. Amplitude adjustment is provided by controlling individual modules in the adder, and is used to compensate for transverse e-beam motion as well as the dynamic response and beam-induced steering effects associated with the kicker structure. A control algorithm calculates a voltage based on measured e-beam displacement and adjusts the modulator to regulate beam centroid position. This paper presents design details of amplitude control along with measured performance data from kicker operation on the ETA-II accelerator at LLNL.

An updated, self-consistent point design for a heavy ion fusion (HIF) power plant based on an induction linac driver, indirect-drive targets, and a thick liquid wall chamber has been completed. Conservative parameters were selected to allow each design area to meet its functional requirements in a robust manner, and thus this design is referred to as the Robust Point Design (RPD-2002). This paper provides a top-level summary of the major characteristics and design parameters for the target, driver, final focus magnet layout and shielding, chamber, beam propagation to the target, and overall power plant.

RIA will produce beams of exotic nuclei of unprecedented luminosity. Preliminary studies of the feasibility of measuring cross-sections of interest to the science based stockpile stewardship (SBSS) program will be presented, and several experimental techniques will be discussed. Cross-section modeling attempts for the A = 95 mass region will be shown. In addition, several radioactive isotopes could be collected for target production or medical isotope purposes while the main in-beam experiments are running. The inclusion of a broad range mass analyzer (BRAMA) capability at RIA will enable more effective utilization of the facility, enabling the performance of multiple experiments at the same time. This option will be briefly discussed.

We have developed a framing tube with 80-mm photocathode for capturing two frames in less than 100-ns onto a 50-mm phosphor screen. A proven electron optics trajectory code was used to design the tube for imaging fidelity over wide dynamic range. This code's full accounting of space charge effects is essential for its ability to simulate accurately the distributed photoelectronic trajectories from the entire large photocathode area. Our approach and guideline for designing the electron optics are described. Results of trajectory simulation and test measurement are reported. Substantial correlations between the code expectation and the measured results are observed on relative resolution and distortion of the frame images. This tube has been integrated into an active framing camera system for field application.

The National Ignition Facility (NIF), currently under construction at the University of California's Lawrence Livermore National Laboratory, is a stadium-sized facility containing a 192-beam, 1.8-Megajoule, 500-Terawatt, 351-nm laser system and a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. NIF is being built by the National Nuclear Security Administration and when completed will be the world's largest laser experimental system, providing a national center to study inertial confinement fusion and the physics of matter at extreme energy densities and pressures. NIF's 192 energetic laser beams will compress fusion targets to conditions where they will ignite and burn, liberating more energy than required to initiate the fusion reactions. NIF experiments will allow the study of physical processes at temperatures approaching 100 million K and 100 billion times atmospheric pressure. These conditions exist naturally only in the interior of stars and in nuclear weapons explosions. In the course of designing the world's most energetic laser system, a number of significant technology breakthroughs have been achieved. NIF is now entering the first phases of its laser commissioning program. Low-energy preamplifier rod laser shots have been successfully propagated through the entire laser chain. Higher energy shots are planned through the end …

Significant progress has been made on addressing critical issues for inertial fusion energy (IFE) chambers for heavy-ion, laser and Z-pinch drivers. A variety of chamber concepts are being investigated including dry-wall (currently favored for laser IFE), wetted-wall (applicable to both laser and ion drivers), and thick-liquid-wall favored by heavy ion and z-pinch drivers. Recent progress and remaining challenges in developing IFE chambers are reviewed.

The ability to detect small amounts of materials, especially whole organisms, is important for medical diagnostics and national security issues. Engineered micro-mechanical systems can serve as multifunctional, highly sensitive, real time, immunospecific biological detectors under certain circumstances. We present qualitative detection of specific Salmonella strains using a functionalized silicon nitride microcantilever. Detection is achieved due to differential surface stress on the cantilever surface in-situ. Scanning electron micrographs indicate that less than 25 adsorbed bacteria are required for detection.

We present updated results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates containing charmonium. In the Standard Model, the amplitude of these asymmetries is proportional to sin2{beta}. We measure sin2{beta} = 0.741 {+-} 0.067 (stat) {+-} 0.034 (syst) from a data sample of about 88 million {Lambda}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We have also measured CP-violating asymmetries in open charm, and penguin modes sensitive to sin2{beta}, which provide important consistency tests of the Standard Model.

Communication-driven scheduling is known to be an effective technique to improve the performance of parallel workloads in time-sharing clusters. Although several such coscheduling algorithms have been proposed, to our knowledge, none of these techniques have been adopted in commercial systems. We believe this is primarily because many of these algorithms has not been exhaustively tested on real systems in presence of mixed workloads, and hence, have not been demonstrated as a favorable alternative to the traditional, batch scheduling. Moreover, practical issues like lack of a methodological approach to efficiently implement, port or reuse the necessary software have dissuaded designers from including coscheduling as a feature in the mainstream system software layer. In this paper, we attempt to fill these crucial voids by addressing several key issues. First, we propose a generic framework for deploying coscheduling techniques by providing a reusable and dynamically loadable kernel module. Second, we implement three prior dynamic coscheduling algorithms (Dynamic coscheduling (DCS), Spin Block (SB) and Periodic Boost (PB)) and a new coscheduling technique, called Co-ordinated coscheduling (CC), using the above framework. Then, we demonstrate the effectiveness of these strategies by implementing a prototype on a Myrinet connected 16-node Linux cluster that uses industry standard Virtual …

The MultiScale ThermoHydrologic Model (MSTHM) predicts thermohydrologic (TH) conditions in emplacement drifts and the adjoining host rock throughout the proposed nuclear-waste repository at Yucca Mountain. The MSTHM is a computationally efficient approach that accounts for TH processes occurring at a scale of a few tens of centimeters around individual waste packages and emplacement drifts, and for heat flow at the multi-kilometer scale at Yucca Mountain. We present recent MSTHM simulations that address the influence of repository-scale thermal-conductivity heterogeneity and the influence of preclosure operational factors affecting thermal-loading conditions. We can now accommodate a complex repository layout with emplacement drifts lying in non-parallel planes using a superposition process that combines results from multiple mountain-scale submodels. This development, along with other improvements to the MSTHM, enables more rigorous analyses of preclosure operational factors. These improvements include the ability to (1) predict TH conditions on a drift-by-drift basis, (2) represent sequential emplacement of waste packages along the drifts, and (3) incorporate distance- and time-dependent beat-removal efficiency associated with drift ventilation. Alternative approaches to addressing repository-scale thermal-conductivity heterogeneity are investigated. We find that only one of the four MSTHM submodel types needs to incorporate thermal-conductivity heterogeneity. For a particular repository design, we find that …

We have developed a compact fieldable optically-deflected streak camera first reported in the 20th HSPP Congress. Using a triggerable galvanometer that scans the optical signal, the imaging and streaking function is an all-optical process without incurring any photon-electron-photon conversion or photoelectronic deflection. As such, the achievable imaging quality is limited mainly only by optical design, rather than by multiple conversions of signal carrier and high voltage electron-optics effect. All core elements of the camera are packaged into a 12 inch x 24 inch footprint box, a size similar to that of a conventional electronic streak camera. At LLNL's Site-300 Test Site, we have conducted a Fabry-Perot interferometer measurement of fast object velocity using this all-optical camera side-by-side with an intensified electronic streak camera. These two cameras are configured as two independent instruments for recording synchronously each branch of the 50/50 splits from one incoming signal. Given the same signal characteristics, the test result has undisputedly demonstrated superior imaging performance for the all-optical streak camera. It produces higher signal sensitivity, wider linear dynamic range, better spatial contrast, finer temporal resolution, and larger data capacity as compared with that of the electronic counterpart. The camera had also demonstrated its structural robustness and …

The capsule targets for ignition experiments at the National Ignition Facility must meet very exacting requirements. Primary among them is an extremely high degree of symmetry at all length scales for the 2-mm-diameter 150-{micro}m-walled capsule. At LLNL work is in progress to produce both polyimide and sputtered beryllium targets that meet these specifications. Both of these targets require a thin-walled spherical-shell plastic mandrel upon which the beryllium or polyimide ablator is deposited. In this paper we report on recent progress in developing NIF capsules that meet the demanding design requirements.

Diffusive x-ray-driven heat waves are found in a variety of astrophysical and laboratory settings, e.g. in the heating of a hohlraum used for ICF, and hence are of intrinsic interest. However, accurate analytic diffusion wave (also called Marshak wave) solutions are difficult to obtain due to the strong non-linearity of the radiation diffusion equation. The typical approach is to solve near the heat front, and by ansatz apply the solution globally. This works fairly well due to ''steepness'' of the heat front, but energy is not conserved and it does not lead to a consistent way of correcting the solution or estimating accuracy. We employ the steepness of the front through a perturbation expansion in {var_epsilon} = {beta}/(4+{alpha}), where the internal energy varies as T{sup {beta}} and the opacity varies as T{sup -{alpha}}. We solve using an iterative approach, equivalent to asymptotic methods that match outer (away from the front) and inner (near the front) solutions. Typically {var_epsilon} < 0.3. Calculations are through first order in {var_epsilon} and are accurate to {approx} 10%, which is comparable to the inaccuracy from assuming power laws for material properties. We solve for supersonic waves with arbitrary drive time history, including the case of …

We are investigating the evaporation of pore water representative of the designated high-level-nuclear-waste repository at Yucca Mountain, NV to predict the range of brine compositions that may contact waste containers. These brines could form potentially corrosive thin films on the containers and impact their long-term integrity. Here we report the geochemistry of a relatively complex synthetic Topopah Spring Tuff pore water that was progressively evaporated in a series of experiments. The experiments were conducted in a closed vessel, heated to 95 C, and purged with atmospheric CO{sub 2}. Aqueous samples of the evaporating solution were taken and analyzed to determine the evolving water chemistry, and the final solid precipitate was analyzed by X-ray diffraction. The synthetic Topopah Spring Tuff water evolved towards a complex brine that contains about 3 mol% SO{sub 4}, and 2 mol% Ca, 3 mol% K, 5 mol% NO{sub 3}, 40 mol% Cl, and 47 mol% Na. Trends in the solution data and identification of CaSO{sub 4} solids (anhydrite and bassanite) suggest that fluorite, carbonate, sulfate, and Mg-silicate precipitation minimize the corrosion potential of ''sulfate type pore water'' by removing F, Ca, and Mg during the early stages of evaporation.

As the world faces growing economic and environmental challenges, the energy mix that fuels the global economy is undergoing rapid change. Yet how this change will evolve in the future is uncertain. What will be the sources of primary energy in twenty years? In fifty years? In different regions of the globe? How will this energy be utilized? Fossil energy currently supplies about ninety percent of the world's primary energy. In Japan this number is closer to eighty percent. It is clear that fossil energy will be a major supplier of global energy for some time to come, but what is not clear is the types of fossil energy and how it will be utilized. The degree to which the abundant supplies of fossil energy, especially coal, will continue to play a major role will depend on whether technology will provide safe, clean and affordable fuel for electricity and transportation. Technology will not only assist in finding more fossil energy in varying regions of the globe but, most importantly, will play a strong role in efficient utilization and in determining the cost of delivering that energy. Several important questions will have to be answered: (1) Will cost effective technologies be …

Multiresolution methods for representing data at multiple levels of detail are widely used for large-scale two- and three-dimensional data sets. We present a four-dimensional multiresolution approach for time-varying volume data. This approach supports a hierarchy with spatial and temporal scalability. The hierarchical data organization is based on 4{radical}2 subdivision. The n{radical}2-subdivision scheme only doubles the overall number of grid points in each subdivision step. This fact leads to fine granularity and high adaptivity, which is especially desirable in the spatial dimensions. For high-quality data approximation on each level of detail, we use quadrilinear B-spline wavelets. We present a linear B-spline wavelet lighting scheme based on n{radical}2 subdivision to obtain narrow masks for the update rules. Narrow masks provide a basis for out-of-core data exploration techniques and view-dependent visualization of sequences of time steps.

New emissions regulations will increase the need for compact, inexpensive sensors for monitoring and control of automotive exhaust gas pollutants. Species of interest include hydrocarbons, carbon monoxide, and oxides of nitrogen (NO{sub x}). The current work is directed towards the development of fast, high sensitivity electrochemical NO{sub x} sensors for automotive diesel applications. We have investigated potentiometric NO sensors with good sensitivity and fast response when operated in 10% O{sub 2}. The sensors consist of yttria-stabilized zirconia substrates attached with NiCr{sub 2}O{sub 4} sensing electrodes and Pt reference electrodes. A composite NiCr{sub 2}O{sub 4}:Rh sensing electrode is shown to give significantly faster response than NiCr{sub 2}O{sub 4} alone. The exact role of the Rh in enhancing the response speed is not clear at present. However, the Rh appears to accumulate at the contacts between the NiCr{sub 2}O{sub 4} particles and may enhance the inter-particle electronic conduction. Ongoing testing of these sensors is being performed to elucidate the sensing mechanisms and to quantify cross sensitivity to, for example, NO{sub 2}.

Hydrodynamic instabilities reduce the yield in inertial confinement fusion (ICF) implosions. Line emission from dopants placed in the capsule can be used to diagnose the extent of the instabilities. This paper presents the results of a large number of 2D simulations and a few 3D simulations of line emission from argon in the DH fuel and titanium placed in the inner layers of the plastic shell of a NOVA ICF capsule. The Simulations have been compared to NOVA experimental data on the ratio of argon Ly-{beta} to titanium He-{alpha}, the relative strength of titanium He-{alpha} and its satellites, and the strength of the continuum near titanium He-{alpha}. The simulations are in reasonable agreement with the data, but the amount of data is small enough that it is hard to make precise comparisons. Two different atomic databases have been used in a first attempt to determine the set of configurations required to properly model the titanium emission.

Finite element modeling has been applied to study deformation of living cells in Atomic Force Microscopy (AFM) and particularly Recognition Force Microscopy (RFM). The abstract mechanical problem of interest is the response to RFM point loads of an incompressible medium enclosed in a fluid membrane. Cells are soft systems, susceptible to large deformations in the course of an RFM measurement. Often the local properties such as receptor anchoring forces, the reason for the measurement, are obscured by the response of the cell as a whole. Modeling can deconvolute these effects. This facilitates experimental efforts to have reproducible measurements of mechanical and chemical properties at specific kinds of receptor sites on the membrane of a living cell. In this article we briefly review the RFM technique for cells and the problems it poses, and then report on recent progress in modeling the deformation of cells by a point load.

Fluorescing surface defects that led to damage upon 351-nm laser exposure below 7 J/cm{sup 2} (3-11s) in DKDP optics were reported in these proceedings by this group a year ago. Subsequent laser damage experiments have correlated the density of these damage precursors to single-point diamond finishing conditions. Every diamond-finishing schedule contains brittle-mode cutting and ductile-mode cutting in a taper-down sequence. Finishing experiments have traced the occurrence of these defects to insufficient ductile-mode removal of subsurface damage incurred during prior brittle-mode cutting. Additionally, a correlation between defect fluorescence, laser-induced damage, and defect morphology has been established. Laser-induced damage tests also suggest a correlation between growth method and damage probability. Current experiments indicate that damage-prone defects can be minimized with the proper choice of diamond finishing conditions.

Over the past several years, significant progress has been made in the analysis of safety and environmental (S&E) issues for inertial fusion energy (IFE). Detailed safety assessments have been performed for the baseline power plant concepts, as well as for a conceptual target fabrication facility. Safety analysis results are helping to drive the agenda for experiments. A survey of the S&E characteristics--both radiological and chemical--of candidate target materials has been completed. Accident initiating events have been identified and incorporated into master logic diagrams, which will be essential to the detailed safety analyses that will be needed in the future. Studies of aerosol generation and transport will have important safety implications. A Monte Carlo-based uncertainty analysis procedure has been developed for use in neutron activation calculations. Finally, waste management issues are receiving increased attention and are deserving of further discussion.

We present a new hybrid algorithm based on Godunov's method for computing eigenvectors of symmetric tridiagonal matrices and Inverse Iteration, which we call the Godunov-Inverse Iteration Algorithm. We use eigenvectors computed according to Godunov's method as starting vectors in the Inverse Iteration, replacing any nonnumeric elements of the Godunov eigenvectors with random uniform numbers. We use the right-hand bounds of the Ritz intervals found by the bisection method as Inverse Iteration shifts, while staying within guaranteed error bounds. In most test cases convergence is reached after only one step of the iteration, producing error estimates that are as good as or superior to those produced by standard Inverse Iteration implementations.

The effect of an individual's travels throughout a day on the spread of disease is examined using a deterministic SIR model. We determine which spatial and demographic characteristics most contribute to the disease spread and whether the progression of the disease can be slowed by appropriate vaccination of people belonging to a specific location-type.