We present the first measurement of the A{sub 2} and A{sub 3} angular coefficients of the W boson produced in proton-antiproton collisions. We study W {yields} ev{sub e} and W {yields} {mu}{nu}{sub {mu}} candidate events produced in association with at least one jet at CDF, during Run Ia and Run Ib of the Tevatron at {radical}s = 1.8 TeV. The corresponding integrated luminosity was 110 pb{sup -1}. The jet balances the transverse momentum of the W and introduces QCD effects in W boson production. The extraction of the angular coefficients is achieved through the direct measurement of the azimuthal angle of the charged lepton in the Collins-Soper rest-frame of the W boson. The angular coefficients are measured as a function of the transverse momentum of the W boson. The electron, muon, and combined results are in good agreement with the Standard Model prediction, up to order {alpha}{sub s}{sup 2} in QCD.

{l_brace}311{r_brace} defects and dislocation loops are formed after ion-implantation and annealing of a silicon wafer. Recent Transmission Electron Microscopy studies by Li and Jones have shown that sub-threshold dislocation loops nucleate from {l_brace}311{r_brace} defects. In our study, the conjugate gradient method with the Stillinger Weber potential is used to relax different configurations such as {l_brace}311{r_brace} defects with a maximum of five chains and perfect dislocation loops. From the formation energies thus obtained we find that there is an optimal width for each length of the {l_brace}311{r_brace} defects. Moreover the relative stability of {l_brace}311{r_brace}s and loops is studied as a function of defect size. We observe that at very small sizes the perfect loops are more stable than the {l_brace}311{r_brace}s. This may provide an explanation for the experimental observation by Robertson et al that, in an annealing study of end of range damage of amorphized samples, 45% of the loops had nucleated in the first 10 minutes of anneal. We propose that homogeneous nucleation, as against unfaulting of the {l_brace}311{r_brace}s, could be the source of these loops.

Increasingly, ADC technology is being pressed into service for single single-shot instrumentation applications that were formerly served by vacuum-tube based oscilloscopes and streak cameras. ADC technology, while convenient, suffers significant performance impairments. Thus, in these demanding applications, a quantitative and accurate representation of these impairments is critical to an understanding of measurement accuracy. We have developed a phase-plane behavioral model, implemented it in SIMULINK and applied it to interleaved, high-speed ADCs (up to 4 gigasamples/sec). We have also developed and demonstrated techniques to effectively compensate for these impairments based upon the model.

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Astronomical applications of adaptive optics at Lawrence Livermore National Laboratory (LLNL) has a history that extends from 1984. The program started with the Lick Observatory Adaptive Optics system and has progressed through the years to lever-larger telescopes: Keck, and now the proposed CELT (California Extremely Large Telescope) 30m telescope. LLNL AO continues to be at the forefront of AO development and science.

This paper discusses issues with the limited precision of hardware-based volume visualization. We will describe the compositing OVER operator and how fixed-point arithmetic affects it. We propose two techniques to improve the precision of fixed-point compositing and the accuracy of hardware-based volume visualization. The first technique is to perform dithering of color and alpha values. The second technique we call exponent-factoring, and captures significantly more numeric resolution than dithering, but can only produce monochromatic images.

The authors present a study of the production of K{sub s}{sup 0} and {Lambda}{sup 0} in inelastic p{bar p} collisions at {radical}s = 1800 and 630 GeV using data collected by the CDF experiment at the Fermilab Tevatron. Analyses of K{sub s}{sup 0} and {Lambda}{sup 0} multiplicity and transverse momentum distributions, as well as of the dependencies of the average number and (p{sub T}) of K{sub s}{sup 0} and {Lambda}{sup 0} on charged particle multiplicity are reported. Systematic comparisons are performed for the full sample of inelastic collisions, and for the low and high momentum transfer subsamples, at the two energies. The p{sub T} distributions extend above 8 GeV/c, showing a (p{sub T}) higher than previous measurements. The dependence of the mean K{sub s}{sup 0}({Lambda}{sup 0}) p{sub T} on the charged particle multiplicity for the three samples shows a behavior analogous to that of charged primary tracks.

We have studied the focusing properties of two highly oriented pyrolitic graphite (HOPG) spectrometers, which differ in the degree of the mosaic spread: ZYA with a low mosaic spread ({gamma}=0.4 degrees) and ZYH with a large mosaic spread ({gamma}=3.5 degrees). In order to assess the crystal performance for a variety of different experiments, various K{alpha} and K{beta} x-ray lines have been produced using a high-intensity ({approx}>10{sup 17} W/cm{sup 2}) short-pulse ({approx} 100 fs) laser beam focused onto Ti, V, Zn, and Cu foils. The measured spectral resolution of the HOPG crystals in both first and second order diffraction has been compared with theoretical predictions. Using known values for the peak reflectivity of HOPG crystals, we have also computed K{alpha} x-ray conversion efficiencies of Ti, V, Zn, and Cu. These results are important to estimate the optimal conditions under which different types of HOPG monochromators can be used for the detection of weak x-ray signals as the one encountered in x-ray Thomson/Compton scattering experiments.

Under the sponsorship of the U.S. DOE and DHS, we have developed a CFD model for simulating flow and dispersion of chemical and biological agents released in the urban environment. Our model, FEM3MP (Chan and Stevens, 2000), is based on solving the three-dimensional, time-dependent, incompressible Navier-Stokes equations on massively parallel computer platforms. The model uses the finite element method for accurate representation of complex building shapes and variable terrain, together with a semi-implicit projection method and modern iterative solvers for efficient time integration (Gresho and Chan, 1998). Physical processes treated include turbulence modeling via the RANS (Reynolds Averaged Navier-Stokes) and LES (Large Eddy Simulation) approaches, atmospheric stability, aerosols, UV radiation decay, surface energy budget, and vegetative canopies, etc. Predictions from our model are continuously being verified and validated against data from wind tunnel (Chan and Stevens, 2000; Chan, et al., 2001) and field experiments (Chan, et al., 2002, 2003; Lee, et al., 2002; Humphreys, et al., 2003; and Calhoun, et al., 2004). Discussed below are several examples to illustrate the use of FEM3MP in simulating flow and dispersion in urban areas and forest canopies, with model results compared against available field measurements.

This paper discusses the background reduction and rejection strategy of the Cryogenic Dark Matter Search (CDMS) experiment. Recent measurements of background levels from CDMS II at Soudan are presented, along with estimates for future improvements in sensitivity expected for a proposed SuperCDMS experiment at SNOLAB.

We have measured the polarization of the heliumlike sulfur resonance line 1s2p {sup 1}P{sub 1} {yields} 1s{sup 2} {sup 1}S{sub 0}, and of the blend of the lithiumlike sulfur resonance lines 1s2s2p {sup 2}P{sub 3/2} {yields} 1s{sup 2}2s {sup 2}S{sub 1/2} and 1s2s2p {sup 2}P{sub 1/2} {yields} 1s{sup 2}2s {sup 2}S{sub 1/2} as a function of electron beam energy from near threshold to 144 keV. These lines were excited with the LLNL high-energy electron beam ion trap and measured using a newly modified two-crystal technique. Our results test polarization predictions in an energy regime where few empirical results have been reported. We also present calculations of the polarization using two different methods, and good agreement is obtained.

The effects of structural perturbation on second harmonic generation in collagen were investigated. Type I collagen fascicles obtained from rat tails were structurally modified by increasing nonenzymatic cross-linking, by thermal denaturation, by collagenase digestion, or by dehydration. Changes in polarization dependence were observed in the dehydrated samples. Surprisingly, no changes in polarization dependence were observed in highly crosslinked samples, despite significant alterations in packing structure. Complete thermal denaturation and collagenase digestion produced samples with no detectable second harmonic signal. Prior to loss of signal, no change in polarization dependence was observed in partially heated or digested collagen.

The X-ray Spectrometer (XRS) instrument is a revolutionary non-dispersive spectrometer that will form the basis for the Astro-E2 observatory to be launched in 2005. We have recently installed a flight spare XRS microcalorimeter spectrometer at the EBIT-I and SuperEBIT facility at LLNL replacing the XRS from the earlier Astro-E mission and providing twice the resolving power. The XRS microcalorimeter is an x-ray detector that senses the heat deposited by the incident photon. It achieves a high energy resolution by operating at 0.06K and by carefully engineering the heat capacity and thermal conductance. The XRS/EBIT instrument has 32 pixels in a square geometry and achieves an energy resolution of 6 eV at 6 keV, with a bandpass from 0.1 to 12 keV (or more at higher operating temperature). The instrument allows detailed studies of the x-ray line emission of laboratory plasmas. The XRS/EBIT also provides an extensive calibration 'library' for the Astro-E2 observatory.

The main objective of this study is to perform nonlinear dynamic earthquake time history analyses on Morrow Point Dam, which is located 263 km southwest of Denver, Colorado. This project poses many significant technical challenges, one of which is to model the entire Morrow Point Dam/Foundation Rock/Reservoir system which includes accurate geology topography. In addition, the computational model must be initialized to represent the existing dead loads on the structure and the stress field caused by the dead loads. To achieve the correct dead load stress field due to gravity and hydrostatic load, the computer model must account for the manner in which the dams were constructed. Construction of a dam finite element model with the correct as-built geometry of the dam structure and simply ''turning on'' gravity in the computer model will generally lead to an incorrect initial stress field in the structure. The sequence of segmented lifts typical of dam construction has a significant impact on the static stress fields induced in the dam. In addition, the dam model must also account for the interaction between the adjacent dam segments across the dam contraction joints. As a result of these challenges, it was determined that a significant amount …

A number of recent works have established the mortar technique as an accurate and robust spatial discretization method for contact problems in computational solid mechanics. Since methods based on this idea rely on an integral, non-local representation of the contact operators, their formulation is somewhat more involved than is true for more traditional ''point to surface'' contact algorithms; in particular, the integral projections have nontrivial linearizations in the fully large deformation context. In this work, we concentrate on another aspect of formulations of this type--definition and implementation of frictional contact operators within the mortar contact framework. Issues associated with frame indifference of frictional tractions and kinematics are discussed, and a numerical demonstration of the technique is given.

Node-on-segment contact is the most common form of contact used today but has many deficiencies ranging from potential locking to non-smooth behavior with large sliding. Furthermore, node-on-segment approaches are not at all applicable to higher order discretizations (e.g. quadratic elements). In a previous work, [3, 4] we developed a segment-to-segment contact approach for eight node hexahedral elements based on the mortar method that was applicable to large deformation mechanics. The approach proved extremely robust since it eliminated the over-constraint that caused 'locking' and provided smooth force variations in large sliding. Here, we extend this previous approach to treat frictional contact problems. In addition, the method is extended to 3D quadratic tetrahedrals and hexahedrals. The proposed approach is then applied to several challenging frictional contact problems that demonstrate its effectiveness.

We have performed two sets of experiments looking at laser-driven radiating blast waves. In one set of experiments the effect of a drive laser's passage through a background gas on the hydrodynamical evolution of blast waves was examined. It was found that the laser's passage heats a channel in the gas, creating a region where a portion of the blast wave front had an increased velocity, leading to the formation of a bump-like protrusion on the blast wave. The second set of experiments involved the use of regularly spaced wire arrays to induce perturbations on a blast wave surface. The decay of these perturbations as a function of time was measured for various wave number perturbations and found to be in good agreement with theoretical predictions.

Tool Gear is a software infrastructure for developing performance analysis and other tools. Unlike existing integrated toolkits, which focus on providing a suite of capabilities, Tool Gear is designed to help tool developers create new tools quickly. It combines dynamic instrumentation capabilities with an efficient database and a sophisticated and extensible graphical user interface. This paper describes the design of Tool Gear and presents examples of tools that have been built with it.

A novel handheld time-domain array GPR antipersonnel mine detection system using an offset paraboloidal reflector antenna is described. The reflector collimates rays from an ultra-wideband transmitting feed, directing the microwave impulse forward, in front of the antenna structure. As such, much of the ground reflected wave is directed further forward, away from the operator, the reflector, and the receiving antennas, and thereby reducing the major source of clutter. The wave transmitted into the ground that interacts with the target, generating significant backscatter returning toward the receiving antennas. These receiving antennas are configured in a 2 by 2 array to provide spatial focusing in both the along- and cross-track directions. This system has been built and tested at both Lawrence Livermore National Laboratory, and GeoCenters, Inc. In both cases, custom-built wideband antenna elements generate narrow pulse shapes, which allow for resolving small non-metallic targets buried at shallow depths. The LLNL's Micro-Power Impulse Radar (MIR) operates in the 1.5 to 5 GHz range a very narrow pulse shape. The Geo-Centers wideband TEMR antenna elements have higher power, though lower frequency range (850 to 1700 MHz), and generate less residual ringing in the time signal. Preliminary measured data from both systems indicate that …

Representative, simplified geothermal rock-fluid systems are investigated with a modeling approach to estimate how rock water interactions affect coupled properties related to mechanical stability and permeability improvement through fracturing. First, geochemical modeling is used to determine the evolution of fluid chemistry at temperatures up to 300 C when fluids are in contact with representative rocks of continental origin. Then, a kinetic crack growth model for quartz is used to predict growth rate for subcritical cracks in acidic and basic environments. The predicted growth rate is highly sensitive to temperature and pH in the ranges tested. At present, the model is limited to situations in which quartz controls the mechanical process of interest, such as well bore stability in silica cemented rocks and the opening of quartz filled veins to enhance permeability.

We have studied the influence of substrate temperature and hydrogen dilution ratio on the properties of silicon thin films deposited on single-crystal silicon and glass substrates. We varied the initial substrate temperature from 200 to 400C and the dilution ratio from 10 to 100. We also studied the effectiveness of the use of a seed layer to increase the crystallinity of the films. The films were analyzed by atomic force microscopy, X-ray diffraction, Raman spectroscopy, and transmission and scanning electron microscopy. We found that as the dilution ratio is increased, the films go from amorphous, to a mixture of amorphous and crystalline, to nanocrystalline. The effect of substrate temperature is to increase the amount of crystallinity in the film for a given dilution ratio. We found that the use of a seed layer has limited effects and is important only for low values of dilution ratio and substrate temperature, when the films have large amounts of the amorphous phase.

Major scientific and technological breakthroughs played a pivotal role in our ability to win the Cold War. The possibility of a different type of war, in response to terrorism, has long been recognized. Indeed, countermeasures to address specific terrorist acts have been developed and are deployed, for example, at special sporting and political events. The current threat environment, however, has created an intense and compelling set of concerns; consequently, the challenge to the scientific Community to develop new concepts and products on an accelerated timeframe is clear. Also, the spectrum of terrorist threats is broad. It includes the use of conventional, chemical, biological, and nuclear and radiological weapons, not to mention cyber-based attacks. The imperatives for advances have been amplified now that attacks are clearly possible within the U.S. borders. For example, advanced sensors and detectors that are able to monitor the proliferation of all the above warfare agents and their movement at entry points into the U.S. are clearly needed. The investments over the last decades in research and development efforts at the U.S. Department of Energy (DOE) national laboratories in nonproliferation have led unique technologies and detection capabilities that have proved useful; yet, many challenges remain. In particular, …

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A hydrogen safety sensor is presented which provides high sensitivity and fast response time when operated in air. The target application for the sensor is external deployment near systems using or producing high concentrations of hydrogen. The sensor is composed of a catalytically active metal-oxide sensing electrode and a noble metal reference electrode attached to an yttria-stabilized zirconia (YSZ) electrolyte. The sensing approach is based on the difference in oxidation rate of hydrogen on the different electrode materials. Results will be presented for a sensor using a sensing electrode of tin-doped indium oxide (ITO). Response to H{sub 2}, and cross-sensitivity to hydrocarbon and H{sub 2}O are discussed.