The mechanical stability of platinum nitride has been studied using first-principles calculations. By calculating the single-crystal elastic constants, we show that platinum nitride can be stabilized in the fluorite structure, in which the nitrogen atoms occupy all the tetrahedral interstitial sites of the metal lattice. The stability is attributed to the pseudogap effect from analysis of the electronic structure.

This article discusses many-body effects in the 4f x-ray photoelectron spectroscopy of the U5+ and U4+ free ions.

The authors propose to develop a high-energy heavy-ion experimental database and make it accessible to the scientific community through an on-line interface. This database will be searchable and cross-indexed with relevant publications, including published detector descriptions. Since this database will be a community resource, it requires the high-energy nuclear physics community's financial and manpower support. This database should eventually contain all published data from Bevalac, AGS and SPS to RHIC and CERN-LHC energies, proton-proton to nucleus-nucleus collisions as well as other relevant systems, and all measured observables. Such a database would have tremendous scientific payoff as it makes systematic studies easier and allows simpler benchmarking of theoretical models to a broad range of old and new experiments. Furthermore, there is a growing need for compilations of high-energy nuclear data for applications including stockpile stewardship, technology development for inertial confinement fusion and target and source development for upcoming facilities such as the Next Linear Collider. To enhance the utility of this database, they propose periodically performing evaluations of the data and summarizing the results in topical reviews.

We have constructed a fast-neutron double-scatter spectrometer that efficiently measures the neutron spectrum and direction of a spontaneous fission source. The device consists of two planes of organic scintillators, each having an area of 125 cm{sup 2}, efficiently coupled to photomultipliers. The four scintillators in the front plane are 2 cm thick, giving almost 25% probability of detecting an incident fission-spectrum neutron at 2 MeV by proton recoil and subsequent ionization. The back plane contains four 5-cm-thick scintillators which give a 40% probability of detecting a scattered fast neutron. A recordable double-scatter event occurs when a neutron is detected in both a front plane detector and a back plane detector within an interval of 500 nanoseconds. Each double-scatter event is analyzed to determine the energy deposited in the front plane, the time of flight between detectors, and the energy deposited in the back plane. The scattering angle of each incident neutron is calculated from the ratio of the energy deposited in the first detector to the kinetic energy of the scattered neutron.

The Long Trace Profiler (LTP) is a precise angle measurement instrument, with a sensitivity and accuracy that can be in the sub-micron radian range. LTP characteristics depend on the particular LTP system schematic design, and the quality of components and assembly. The conditions of temperature, alignment, and mirror support during the measurement process vary between different laboratories, which influences significantly the test repeatability and accuracy. In this paper we introduce a direct comparison method to test the same object at the same point in the same environment at the same time by using two LTPs, which significantly increases the reliability of the comparison. A compact, portable LTP (PTLTP), which can be carried to different laboratories around the world, is used for comparison testing. Stability Comparison experiments between the LTP II at the National Synchrotron Radiation Research Center (NSRRC), and the PTLTP of Brookhaven National Laboratory (BNL) reveal significant differences in performance between the instruments. The experiment is set up so that each optical head simultaneously records both its own sample probe beam and also the probe beam from the other optical head. The two probe beams are reflected from same point on the mirror. Tests show that the stability of …

Pulse shape analysis is proved to be a powerful tool to characterize the performance of CdZnTe devices and understand their operating principles. It allows one to investigate the device configurations, electron transport properties, effects governing charge collection, electric-field distributions, signal charge formation, etc. This work describes an application of different techniques based on the pulse shape measurements to characterize pixel, coplanar-grid, and virtual Frisch-grid devices and understand the electronic properties of CZT material provided by different vendors. We report new results that may explain the performance limits of these devices.

The Long Trace Profiler (LTP) is a useful optical metrology instrument for measuring the figure and slope error of cylindrical aspheres commonly used as synchrotron radiation (SR) optics. It is used extensively at a number of synchrotron radiation laboratories around the world. In order to improve SR beam line quality and resolution, the National Synchrotron Radiation Laboratory (NSRL) of China is developing a versatile LTP that can be used to measure both SR optics and more conventional ''normal'' optical surfaces. The optical metrology laboratories at Brookhaven National Laboratory (BNL) and NSRL are collaborating in developing a multiple functions LTP (LTP-MF). Characteristics of the LTP-MF are: a very compact and lightweight optical head, a large angular test range ({+-} 16 mad) and high accuracy. The LTP-MF can be used in various configurations: as a laboratory-based LTP, an in-situ LTP or penta-prism LTP, as an angle monitor, a portable LTP, and a small radius of curvature test instrument. The schematic design of the compact optical head and a new compact slide are introduced. Analysis of different measurements modes and systematic error correction methods are introduced.

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We present simulation results from a new computational model of DNA flow in microfluidic devices. This work is important because computational models are needed to design miniaturized biomedical devices that are becoming the state-of-the-art in many significant applications including pathogen detection as well as continuous monitoring and drug delivery. Currently advanced algorithms in design tools are non-existent but necessary to understand the complex fluid and polymer dynamics involved in biological flow at small scales. Our model is based on a fully coupled fluid-particle numerical algorithm with both stochastic and deterministic components in a bead-rod polymer representation. We have applied this work to DNA extraction configurations in a microfluidic PCR chamber used in a pathogen detection system. We demonstrate our method on the test problem of flow of a single DNA molecule in a 2D packed array microchannel. We are also investigating mechanisms for molecular ''sticking'' using short range forces.

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New results from studies of coplanar-grid CdZnTe (CZT) detectors are presented. The coplanar-grid detectors, were investigated by using a highly collimated X-ray beam available at Brookhaven's National Synchrotron Light Source and by applying a pulse-shape analysis. The coplanar-grid detector operates as a single-carrier device. Despite the fact that its operational principle is well known and has been investigated by many groups in the past, we found some new details that may explain the performance limits of these types of devices. The experimental results have been confirmed by extensive computer modeling.

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This article discusses low-coordinate iron dinitrogen complexes. Understanding the interaction of N₂ with iron is relevant to the iron catalyst used in the Haber process and to possible roles of the FeMoco active site of nitrogenase.

We use on-shell recursion relations to determine the one-loop QCD scattering amplitudes with a massless external quark pair and an arbitrary number (n - 2) of positive-helicity gluons. These amplitudes are the last of the unknown infrared- and ultraviolet-finite loop amplitudes of QCD. The recursion relations are similar to ones applied at tree level, but contain new non-trivial features corresponding to poles present for complex momentum arguments but absent for real momenta. We present the relations and the compact solutions to them, valid for all n. We also present compact forms for the previously-computed one-loop n-gluon amplitudes with a single negative helicity and the rest positive helicity.

Tenascin-X is an extracellular matrix protein initially identified because of its overlap with the human CYP21B gene. Because studies of gene and protein function of other tenascins had been poorly predictive of essential functions in vivo, we used a genetic approach that critically relied on an understanding of the genomic locus to uncover an association between inactivating tenascin-X mutations and novel recessive and dominant forms of Ehlers-Danlos syndrome. Tenascin-X provides the first example of a gene outside of the fibrillar collagens and their processing enzymes that causes Ehlers-Danlos syndrome. Tenascin-X null mice recapitulate the skin findings of the human disease, confirming a causative role for this gene in Ehlers-Danlos syndrome. Further evaluation of these mice showed that tenascin-X is an important regulator of collagen deposition in vivo, suggesting a novel mechanism of disease in this form of Ehlers-Danlos syndrome. Further studies suggest that tenascin-X may do this through both direct and indirect interactions with the collagen fibril. Recent studies show that TNX effects on matrix extend beyond the collagen to the elastogenic pathway and matrix remodeling enzymes. Tenascin-X serves as a compelling example of how human experiments of nature can guide us to an understanding of genes whose function may …

A parameter study was performed to examine the (shock) damage obtained with long-rod and spherical mono-material penetrators impacting two varieties of limestone. In all cases, the impacts were assumed to be normal to the plane of the rock and at zero angle of attack (in the case of the rods). Impact velocities ranged to 15 km/s but most calculations were performed at 4 and 6 km/s and the penetrator mass was fixed at 1000 kg. For unlined underground structures, incipient damage was defined to occur when the peak stress, {sigma}{sub pk}, exceeds 1 kb (100 MPa) and the applied impulse per unit area, I{sub pk}, exceeds 1 ktap (1 kb-{micro}s). Severe damage was assumed to occur when {sigma}{sub pk} exceeds 1 kb and I{sub pk} exceeds 1000 ktaps. Using the latter definition it was found that severe damage in hard, non-porous limestone with spherical impactors extended to a depth of 9 m on-axis for an impact velocity of 4 km/s and 12 m at 6 km/s. Cylinders with length-to-diameter (L/D) ratio of 8.75 achieved depth to severe damage of 23 m and 40 m, respectively under the same conditions. For a limestone medium with 2% initial gas porosity, the latter …

A study of several 3- and 4-body hadronic final states ({pi}{sup +}{pi}{sup -}{pi}{sup 0}, {pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -}, K{sup +}K{sup -}{pi}{sup +}{pi}{sup -} and K{sup +}K{sup -}K{sup +}K{sup -}) accompanied by hard photon is presented. These states are produced from e{sup +}e{sup -} collisions at the c.m. energy near {Upsilon}(4S) resonance using 90 fb{sup -1} data sample collected with the BABAR detector at the PEP-II collider. The invariant mass of the hadronic final state determines the virtual photon energy, so that data can be compared with direct e{sup +}e{sup -} cross sections. The cross sections for the above final states have been obtained from the threshold to 4.5 GeV with about 5% systematic errors. The accuracy of the results are comparable with the best direct e{sup +}e{sup -} results overall and with much better precision in 1.4-2.5 GeV region where very few data are available. In addition to light meson spectroscopy these data can be used to improve the determination of R--the ratio of e{sup +}e{sup -} {yields} hadrons cross section to e{sup +}e{sup -} {yields} {mu}{sup +}{mu}{sup -}--and thereby to impact the understanding of recent (g - 2){sub {mu}} measurement. The ISR technique also gives access to J/{psi} …

We present a computational study on the penetration of steel projectiles into porous geologic materials. The purpose of the study is to extend the range of applicability of a recently developed constitutive model to simulations involving projectile penetration into geologic media. The constitutive model is non-linear, thermodynamically consistent, and properly invariant under superposed rigid body motions. The equations are valid for large deformations and they are hyperelastic in the sense that the stress tensor is related to a derivative of the Helmholtz free energy. The model uses the mathematical structure of plasticity theory to capture the basic features of the mechanical response of geological materials including the effects of bulking, yielding, damage, porous compaction and loading rate on the material response. The new constitutive model has been successfully used to simulate static laboratory tests under a wide range of triaxial loading conditions, and dynamic spherical wave propagation tests in both dry and saturated geologic media.

For experimental campaigns on the National Ignition Facility (NIF) to be successful, they must obtain useful data without causing unacceptable impact on the facility. Of particular concern is excessive damage to optics and diagnostic components. There are 192 fused silica main debris shields (MDS) exposed to the potentially hostile target chamber environment on each shot. Damage in these optics results either from the interaction of laser light with contamination and pre-existing imperfections on the optic surface or from the impact of shrapnel fragments. Mitigation of this second damage source is possible by identifying shrapnel sources and shielding optics from them. It was recently demonstrated that the addition of 1.1-mm thick borosilicate disposable debris shields (DDS) block the majority of debris and shrapnel fragments from reaching the relatively expensive MDS's. However, DDS's cannot stop large, faster moving fragments. We have experimentally demonstrated one shrapnel mitigation technique showing that it is possible to direct fast moving fragments by changing the source orientation, in this case a Ta pinhole array. Another mitigation method is to change the source material to one that produces smaller fragments. Simulations and validating experiments are necessary to determine which fragments can penetrate or break 1-3 mm thick DDS's. …

To successfully tune the DARHT II transport beamline requires the close coupling of a model of the beam transport and the measurement of the beam observables as the beam conditions and magnet settings are varied. For the ETA II experiment using the DARHT II beamline components this was achieved using the SUICIDE (Simple User Interface Connecting to an Integrated Data Environment) data analysis environment and the FITS (Fully Integrated Transport Simulation) model. The SUICIDE environment has direct access to the experimental beam transport data at acquisition and the FITS predictions of the transport for immediate comparison. The FITS model is coupled into the control system where it can read magnet current settings for real time modeling. We find this integrated coupling is essential for model verification and the successful development of a tuning aid for the efficient convergence on a useable tune. We show the real time comparisons of simulation and experiment and explore the successes and limitations of this close coupled approach.

DER-CAM Developed by the Lawrence Berkeley National Laboratory (LBNL), is an optimization tool for DER technology selection. However it can not be simply applied to the Japanese case because of the different climate and the utility tariff. This research aims to develop an optimization tool for distributed energy for Japanese buildings using GAMS, a high-level modeling system for mathematical programming and optimization. This paper describes how we apply and demonstrate the tool to the energy center at Kitakyushu Research city, where has installed a fuel cell and a gas engine. An analysis has also been conducted to see how the utility tarriff and the equipment efficiency can affect the operation of the DER system.

A method is presented for using the statistical design of experiment (2{sup k} Factorial Design) technique in the sensitivity analysis of the thermal response (temperature) of the 9975 radioactive material packaging where multiple thermal properties of the impact absorbing and fire insulating material Celotex and certain boundary conditions are subject to uncertainty. 2{sup k} Factorial Design method is very efficient in the use of available data and is capable of analyzing the impact of main variables (Factors) and their interactions on the component design. The 9975 design is based on detailed finite element (FE) analyses and extensive proof testing to meet the design requirements given in 10CFR71 [1]. However, the FE analyses use Celotex thermal properties that are based on published data and limited experiments. Celotex is an orthotropic material that is used in the home building industry. Its thermal properties are prone to variation due to manufacturing and fabrication processes, and due to long environmental exposure. This paper will evaluate the sensitivity of variations in thermal conductivity of the Celotex, convection coefficient at the drum surface, and drum emissivity (herein called Factors) on the thermal response of 9975 packaging under Normal Conditions of Transport (NCT). Application of this methodology …

We report on the operation of the Mercury laser with fourteen 4 x 6 cm{sup 2} Yb:S-FAP amplifier slabs pumped by eight 100 kW peak power diode arrays. The system was continuously run at 55 J and 10 Hz for several hours, (2 x 10{sup 5} cumulative shots) with over 80% of the energy in a 6 times diffraction limited spot at 1.047 um. Improved optical quality was achieved in Yb:S-FAP amplifiers with magneto-rheological finishing, a deterministic polishing method. In addition, average power frequency conversion employing YCOB was demonstrated at 50% conversion efficiency or 22.6 J at 10 Hz.

A new 5kV, 1.5MJ modular capacitor bank has been designed for the Sustained Spheromak Physics Experiment (SSPX) at LLNL. The new bank consists of thirty 4mF capacitors that are independently controlled by light-triggered thyristors. By closing all switches simultaneously, the bank will provide a mega-ampere discharge. The new bank will also allow additional capabilities to SSPX, including higher peak gun current, longer current pulses, and multi-pulse plasma buildup. Experiment results for a single stage prototype will be presented, deliver a single large current spike, or, switches can be triggered in sequence to deliver a longer lower current pulse. Multiple pulses can be created by triggering sections of the modular bank in intervals.