Performance requirements, design concepts, and test results for a prototype multipulse kicker modulator based on solid-state switches and a voltage-adding transformer topology are described. Tape-wound cores are stacked to form the transformer primary windings and a cylindrical pipe that passes through the circular inner diameters of the cores serves as the secondary winding of the step-up transformer. Boards containing MOSFET switches, trigger circuitry, and energy-storage capacitors plug into the core housings. A 50 kV prototype modulator that meets most of the facility requirements has been designed, fabricated, and tested at LLNL. More recent work has been concerned with designing and testing cores and boards with the full volt-second capability needed for 24-pulse operation. Results of the 50 kV prototype tests, preliminary tests of the full-volt-second cores and boards, and future development needs are described.

Welcome to the Proceedings of the fourth in a series of agent simulation conferences cosponsored by Argonne National Laboratory and The University of Chicago. Agent 2003 is the second conference in which three Special Interest Groups from the North American Association for Computational Social and Organizational Science (NAACSOS) have been involved in planning the program--Computational Social Theory; Simulation Applications; and Methods, Toolkits and Techniques. The theme of Agent 2003, Challenges in Social Simulation, is especially relevant, as there seems to be no shortage of such challenges. Agent simulation has been applied with increasing frequency to social domains for several decades, and its promise is clear and increasingly visible. Like any nascent scientific methodology, however, it faces a number of problems or issues that must be addressed in order to progress. These challenges include: (1) Validating models relative to the social settings they are designed to represent; (2) Developing agents and interactions simple enough to understand but sufficiently complex to do justice to the social processes of interest; (3) Bridging the gap between empirically spare artificial societies and naturally occurring social phenomena; (4) Building multi-level models that span processes across domains; (5) Promoting a dialog among theoretical, qualitative, and empirical social …

One of the longstanding obstacles to the use of the MCNP Monte Carlo code' for reactor physics calculations has been its requirement for nuclear data libraries at the temperature associated with the application of interest. Recently, however, an auxiliary code, named 'doppler,' has been developed that uses an existing nuclear data library as the basis for generating a new library at the desired temperature. doppler has simple input and is straightforward to use. Libraries generated with doppler and based on the existing ENDF66 library have been developed for three hot Kritz benchmark. Results obtained from MCNPS for those hot benchmarks and their cold (ie., room-temperature) counterparts are presented herein.

In 1992, LIBS was proposed as a new method for stand-off detection of geological samples for use on landers and rovers to Mars. Recently, there has been increased interest in the technique for this and other space applications and studies have determined some of the characteristics and capabilities of the method under the conditions that these measurements will have to be made. In addition to rocks and soils, there is interest in using LIBS to analyze ices and dusts entrained in ice . This is especially true for missions to the Mars polar regions . Of particular interest is determining the nature of polar layered deposits, the geochemistry of polar surface materials, detection of water ice and the distribution of ice, and the presence of possible organics in these materials (via C/N ratios)

We analyze the current matrix elements in the general collinear (Breit) frames and find the relation between the ordinary (or canonical) helicity amplitudes and the light-front helicity amplitudes. Using the conservation of angular momentum, we derive a general angular condition which should be satisfied by the light-front helicity amplitudes for any spin system. In addition, we obtain the light-front parity and time-reversal relations for the light-front helicity amplitudes. Applying these relations to the spin-1 form factor analysis, we note that the general angular condition relating the five helicity amplitudes is reduced to the usual angular condition relating the four helicity amplitudes due to the light-front time-reversal condition. We make some comments on the consequences of the angular condition for the analysis of the high-Q{sup 2} deuteron electromagnetic form factors, and we further apply the general angular condition to the electromagnetic transition between spin-1 /2 and spin-3/2 systems and find a relation useful for the analysis of the N-Delta transition form factors. We also discuss the scaling law and the subleading power corrections in the Breit and light-front frames.

As the archetype magnetic intermetallic compounds IJNiAI (antiferromagnet, TN = 19K) and URhAI (ferromagnet, TC = 27K) [1] ., iJNi0.39Rh0.61A1 crystallizes in the hexagonal ZrNiAI-type structure . UNi0 .39Rh0.61A1 undergoes antiferromagnetic (AF) at TN = 13K . Here, we report on resistance and magnetoresistance studies on single-crystalline UNi0 .39Rh0.61A1 in magnetic field up to 18T applied along and perpendicular to the c-axis. 20-Tesla National High Magnetic Field Laboratory (NHMFL) at Los Alamos has been used to investigate such magnetic properties . This compound is found to exhibit highly anisotropic properties with the easy magnetization axis along the c-axis . While for fields applied along c-axis, 3T completely suppresses the AF ordering, antiferromagnetism persists up to the highest field of 18T applied perpendicular to the c-axis, see Fig.(1) which shows R(ohm) vs B (T) . The results are discussed in terms of variation of the 5f-ligand hybridization compared to the one of its parent compounds.

A study was performed at the University of Florida to measure ground penetrating radar(GPR) performance for detecting forensic burials. In controlled scenarios, 24 burials were constructed with pig cadavers. Two soils were utilized to represent two of the most common soil orders in Florida: an Entisol and an Ultisol. Graves were monitored on a monthly basis for time periods up to 21 months with grid data acquired with pulsed and swept-frequency GPR systems incorporating several different frequency antennas. A small subset of the graves was excavated to assess decomposition and relate to the GPR images during the test. The grave anomalies in the GPR depth profiles became less distinctive over time due to body decomposition and settling of the disturbed soil (backfill) as it compacted. Soil type was a major factor. Grave anomalies became more difficult to recognize over time for deep targets that were within clay. Forensic targets that were in sandy soil were recognized for the duration of this study. Time elapsed imagery will be presented to elucidate the changes, or lack thereof, of grave anomalies over the duration of this study. Further analysis was performed using Synthetic Aperture Radar (SAR) reconstruction of images in 2-D and 3-D.

Ductile failure criteria suitable for application to impulsively loaded high pressure vessels that are designed to the rules of the ASME Code Section VI11 Division 3 are described and justified. The criteria are based upon prevention of load instability and the associated global failure mechanisms, and on protection against progressive distortion for multiple-use vessels. The criteria are demonstrated by the design and analysis of vessels that contain high explosive charges.

The aging properties of plutonium (Pu) metal and alloys are. driven by a combination of materials composit ion, p rocessing history, and self-irradiat ion effects . Understanding these driving forces requires a knowledge of both t h ermodynamic and defect properties of the material . The multiplicity of phases and the small changes in tempe rat u re, pressure, and/or stress that can induce phase changes lie at the heart of these properties . In terms of radiation damage, Pu metal represents a unique situation because of the large volume chan ges that accompany the phase changes . The most workable form of the meta l is the fcc (S-) phase, which in practice is stabi l ized by addit io n of a ll oying el eme n ts s u c h as Ga or Al. The thermodynamically stable phase at ambient conditions is the monoclinic (a-) phase, which, however, is 2 0 % lower i n volume th an the S phase . In stabilized Pu metal, there is an in t er play between th e n atu ral swe l li n g tendencies of fcc metals and the volume-contraction tendency of the u n …

This paper describes an algorithm for the registration of imagery collected by the Multispectral Thermal Imager (MTI). The Automated Image Registration (AIR) algorithm is entirely image-based and is implemented in an automated fashion, which avoids any requirement for human interaction. The AIR method differs from the 'direct georeferencing' method used to create our standard coregistered product since explicit information about the satellite's trajectory and the sensor geometry are not required. The AIR method makes use of a maximum cross-correlation (MCC) algorithm, which is applied locally about numerous points within any two images being compared. The MCC method is used to determine the row and column translations required to register the bands of imagery collected by a single SCA (band-to-band registration), and the raw and column translations required to regisler the imagery collected by the three SCAs for any individual band (SCA-to-SCA registration). Of particular note is the use of reciprocity and a weighted least squares approach to obtaining the band-to-band registration shifts. Reciprocity is enforced by using the MCC method to determine the row and column translations between all pair-wise combinations of bands. This information is then used in a weighted least squares approach to determine the optimum shift values …

BCS MPI proposes a new approach to design the communication libraries for large scale parallel machines. The emphasis of BCS MPI is on the global coordination of the potentially large number of processes and in the reduction of the non determinism rather than in the traditional optimization of the local performance of a pair of communicating processes. BCS MPI delays the interprocessor communication in order to schedule globally the communication pattern and it is designed on top of a minimal set of collective communication primitives. In this paper we describe a prototype implementation of BCS MPI and its communication protocols. The experimental results, executed on a set of scientific applications representative of the ASCI workload, show that BCS MPI is only marginally slower than the production-level MPI, but much simpler to implement, debug and analyze.

Buffered Co-Scheduled (BCS) MPI proposes a new approach to design the communication libraries for large-scale parallel machines. The emphasis of BCS MPI is on the global coordination of a large number of processes rather than in the traditional optimization of the local performance of a pair of communicating processes. BCS MPI delays the interprocessor communication in order to schedule globally the communication pattern and it is designed on top of a minimal set of collective communication primitives. In this paper we describe a prototype implementation of BCS MDI and its Communication protocols. The experimental results, executed on a set of scientific applications representative of the ASCI workload, show that BCS MPI is only marginally slower than the production-level MPI, but much simpler to implement, debug and analyze.

Using self-consistent field theory, we attempt to elucidate the links between microscopically determined properties, such as the bridging fraction of chains, and mechanical properties of multiblock copolymer materials. We determine morphological aspects such as period and interfacial width and calculate the bridging fractions, and compare with experimental data .

Press kit containing articles about the launching of Brilliant Magazine by Brilliance Media in Austin, Texas.

Using molecular dynamics and a modified embedded atom potential developed by our group we studied the diffusivity and viscosity of molten Nil-XZrX alloys as a function of composition, temperature, and cooling rate. Previous results indicate that these potentials represent the Ni-Zr system quite well . Liquid alloys were quenched at rates of 5 x 10{sup 11} and 10{sup 12} K/s. For x < 0.04 the solidified alloys were crystalline . For higher x values, the solidified alloys were amorphous . For the amorphous alloys, the composition dependence of the calculated glass transition temperature Tg follows the general trend of experimental Tg values . The calculated viscosity and diffusivity show systematic variation with composition . For the undercooled Ni-6 at .% Zr melt the calculated viscosity shows the Vogel-Fulcher-Tamman (VFT) behavior characteristic of a 'fragile' glass .

Developing regional discriminants (RDs) at any given seismic station requires a ground-truth database of waveforms from both earthquakes and explosions. Recently installed stations used for seismic monitoring have no single charge explosions on which to base discriminants. We have developed a procedure to map information from surrogate stations, having a long recording history, to newly installed operational stations. We investigated a method to compute transfer functions using known effective 13Ds for a database of earthquakes and explosions located near the Lop Nor nuclear test site and recorded at the KNET array in Kyrgyzstan. For specific source-station paths, transfer functions work well. However, preliminary analysis of India and Pakistan nuclear tests indicate strong azimuthal dependence in the construction of reliable transfer functions. The success of the preliminary work suggests we can apply the same technique to calibrate the recently installed MKAR array using the Global Seismic Network station MAKZ as a surrogate. Both MKAR, an 11-element array operational since 2000, and MAKZ (including its earlier counterpart MAK), operating very broadband instruments since 1994, are located in Eastern Kazakhstan and separated by 25 km. To perform the calibration requires additional considerations not taken into account during the initial investigation: (1) utilizing amplitude …

Great interest was generated with the discovery by the Odyssey spacecraft OC heterogeneously distributed hydrogcn at martian mid-latitudes, suggesting that large areas of the near-equatorial highlands contain near-surface deposits of 'chemically and/or physically bound 1120 and/or OH' in amounts up to 3.8% equivalent H20. More recent interpretations of the Odyssey data using new calibrations suggest that some near-equatorial areas, such as Arabia Terra, contain up to 8.5f I .3% water-equivalent hydrogen. Such shallow occurrences (<I tn) of H20 ice near the martian equator are particularly enigmatic because H20 ice is not stable at these latitudes. A number of potentially hydrous silicate phases, notably clay minerals and zeolites, have been proposed as possible M20-bearing constituents on Mars, and both groups of minerals are common terrestrial alteration products of hydrovolcanic basaltic ashes and palagonitic material comparable io those that may be widespread on Mars. Smectites within martian meteorites, attributed to hydrous alteration on Mars rather than on Earth, provide direct evidence of clay minerals from Mars. In addition, new thermal emission spectrometer (TES) data provide evidence for unspecified zeolites in martian surface dust, and concluded that spectral deconvolution of MGS TES and Mariner 9 IRIS data is consistent with the presence of …

The possible need for an economical method for the separation of CO2 from flue gas adds a new set of challenges to power plant design, construction, operation, and maintenance. Many of the new requirements of CO2 separation are similar in nature to those addressed by the mature chemical engineering processes used in petroleum refining and industrial chemical production. Chemical engineering processes are regularly used to separate heterogeneous vapors in processes such as the fractionation of hydrocarbons or the separation of the components of air. This paper addresses the application of chemical engineering processes to the mixtures of gases and vapors found in the flue gas of recirculating boilers. Adaptation of these techniques can lead to a reduction in the energy required to capture CO2.

The dramatic increase in atmospheric carbon dioxide since the Industrial Revolution has caused concerns about global warming. Fossil-fuel-fired power plants contribute approximately one third of the total human-caused emissions of carbon dioxide. Increased efficiency of these power plants will have a large impact on carbon dioxide emissions, but additional measures will be needed to slow or stop the projected increase in the concentration of atmospheric carbon dioxide. By accelerating the naturally occurring carbonation of magnesium silicate minerals it is possible to sequester carbon dioxide in the geologically stable mineral magnesite (MgCO3). The carbonation of two classes of magnesium silicate minerals, olivine (Mg2SiO4) and serpentine (Mg3Si2O5(OH)4), was investigated in an aqueous process. The slow natural geologic process that converts both of these minerals to magnesite can be accelerated by increasing the surface area, increasing the activity of carbon dioxide in the solution, introducing imperfections into the crystal lattice by high-energy attrition grinding, and in the case of serpentine, by thermally activating the mineral by removing the chemically bound water. The effect of temperature is complex because it affects both the solubility of carbon dioxide and the rate of mineral dissolution in opposing fashions. Thus an optimum temperature for carbonation of olivine …

In this paper we describe how we improved the effective performance of ASCI Q, the world's second-fastest supercomputer, to meet our expectations. Using an arsenal of performance-analysis techniques including analytical models, custom microbenchmarks, full applications, and simulators, we succeeded in observing a serious-but previously undetectable-performance problem. We identified the source of the problem, eliminated the problem, and 'closed the loop' by demonstrating improved application performance. We present our methodology and provide insight into performance analysis that is immediately applicable to other large-scale cluster-based supercomputers.

The CEBAF Large Acceptance Spectrometer (CLAS) is used to study photo- and electro-induced nuclear and hadronic reactions by providing efficient detection of neutral and charged particles over a good fraction of the full solid angle. A collaboration of about thirty institutions has designed, assembled, and commissioned CLAS in Hall B at the Thomas Jefferson National Accelerator Facility. The CLAS detector is based on a novel six-coil toroidal magnet which provides a largely azimuthal field distribution. Trajectory reconstruction using drift chambers results in a momentum resolution of 0.5% at forward angles. Cerenkov counters, time-of-flight scintillators, and electromagnetic calorimeters provide good particle identification. Fast triggering and high data acquisition rates allow operation at a luminosity of 10{sup 34} nucleon cm {sup -2}s{sup -1}. These capabilities are being used in a broad experimental program to study the structure and interactions of mesons, nucleons, and nuclei using polarized and unpolarized electron and photon beams and targets. This paper is a comprehensive and general description of the design, construction and performance of CLAS.

We compare macroparticle simulations with beam-profile measurements from a proton beam-halo experiment in a study of beam-halo formation in mismatched beams in a 52-quadrupole periodic-focusing channel. The lack of detailed measurement of the initial distribution is an important issue for being able to make reliable predictions of the halo. We have found earlier that different initial distributions with the same Courant-Snyder parameters and emittances produce similar matched-beam profiles, but different mismatched-beam profiles in the transport system. Also, input distributions with greater population in the tails produce larger rates of emittance growth. We have concluded that using only the known Courant-Snyder parameters and emittances as input parameters is insufficient information for reliable simulations of beam halo formed in mismatched beams. The question is how to obtain the best estimate of the input beam distribution needed for more accurate simulations. In this paper, we investigate a new least squares fitting procedure, which is applied to the simulations used to determine the injected beam distribution, in an attempt to obtain a more accurate description of halo formation than fiom simulation alone.

Both galaxies and charged particle beams can exhibit collective relaxation on surprisingly short time scales. This can be attributed to the effects of chaos, often triggered by resonances caused by time-dependences in the bulk potential, which act almost identically for attractive gravitational and repulsive electrostatic forces. These similarities suggest that many physical processes at work in galaxies, albeit not subject to direct controlled experiments, can be tested indirectly using facilities such as the University of Maryland Electron Ring (UMER) currently nearing completion.

LIBS has been proposed as a new method for stand-off detection of geological samples for use on landers and rovers to Mars and studies are on-going to determine capabilities. Because of the severe size, weight, ruggedness and power requirements for space instrumentation and the need to maximize scientific return, it is important to benchmark capabilities with parameters representative of compact instrumentation likely to be used in a flight instrument. Some of these issues are addressed here.