A series of hydrothermal zeolite synthesis were performed on a powder diffractometer using synchrotron radiation and a position sensitive detector. Direct observation of the induction period (nucleation stage), crystallization and transformation of zeolite 4A (Na-LTA) was possible due to the intense X-ray beam which allows fast data collection. High pressure experiments were performed, allowing observation of hydrothermal synthesis of a cobalt substituted AlPO{sub 4}-zeolite, CoAPO-5, up to 165{degrees}C. The temperature dependence of crystallization rates of CoAPO-5 was studied. This is to our knowledge the first time resolved powder diffraction studies of zeolite syntheses using angle dispersive synchrotron powder diffraction.

The authors introduce here a new technique for sorting magnets to minimize the field errors in permanent magnet insertion devices. Simulated annealing has been used in this role, but they find the technique of threshold acceptance produces results of equal quality in less computer time. Threshold accepting would be of special value in designing very long insertion devices, such as long FEL`s. Their application of threshold acceptance to magnet sorting showed that it converged to equivalently low values of the cost function, but that it converged significantly faster. They present typical cases showing time to convergence for various error tolerances, magnet numbers, and temperature schedules.

The storage of aluminum-clad fuel and target materials in the L-Disassembly Basin at the Savannah River Site for more than 5 years has resulted in extensive pitting corrosion of these materials. In many cases the pitting corrosion of the aluminum clad has penetrated in the uranium metal core, resulting in the release of plutonium, uranium, cesium-137, and other fission product activity to the basin water. In an effort to characterize the extent of corrosion of the Mark 31A target slugs, two unirradiated slug assemblies were removed from basin storage and sent to the Savannah River Technology Center for evaluation. This paper presents the results of the metallography and photographic documentation of this evaluation. The metallography confirmed that pitting depths varied, with the deepest pit found to be about 0.12 inches (3.05 nun). Less than 2% of the aluminum cladding was found to be breached resulting in less than 5% of the uranium surface area being affected by corrosion. The overall integrity of the target slug remained intact.

Workers at two Department of Energy facilities, the Pantex Plant in Texas and the Hanford Site in Washington, are potentially exposed to class Y depleted or natural uranium. Since trace amounts of uranium are naturally present in urine excretion, site bioassay programs must be able to discern occupational exposure from naturally occurring uranium exposure. In 1985 Hanford established a 0.2-{mu}g/d environmental screening level for elemental uranium in urine; the protocol was based on log-normal probability analysis of unexposed workers. A second study of background uranium levels commenced in 1990, and experiences in the field indicated that there seemed to be an excessive number of urine samples with uranium above the screening level and that the environmental screening level should be reviewed. Due to unforeseen problems, that second study was terminated before the complete data could be obtained. Natural uranium in rock (by weight, 99.27% {sup 288}U, 0.72% {sup 235}U, and 0.006% {sup 234}U) has approximately equal activity concentrations of {sup 238}U and {sup 234}U. Earlier studies, summarized by the U.S. Environmental Protection Agency in 51 FR 32068, have indicated that {sup 234}U (via {sup 234}Th) has a greater environmental mobility than {sup 238}U and may well have a higher concentration …

The DIRC is a totally internally reflecting Cherenkov imaging detector proposed for particle identification at the asymmetric e{sup +}e{sup {minus}} B factories. First test results from a conceptual prototype using cosmic muons are reported. The photo-electron yield and the single Cherenkov photon resolution at various track dip angles and positions along the radiator bar have been measured. The results are consistent with estimates and Monte-Carlo simulations.

This paper reviews several different models for light interaction with volume densities of absorbing, glowing, reflecting, or scattering material. They include absorption only, glow only, glow and absorption combined, single scattering of external illumination, and multiple scattering. The models are derived from differential equations, and illustrated on a data set representing a cloud. They are related to corresponding models in neutron transport. The multiple scattering model uses an efficient method to propagate the radiation which does not suffer from the ray effect.

All manufacturing processes involve errors. In the case of bare and multilayer mirrors these unavoidable errors introduce near-field fluctuations in the reflected wavefront which propagate to the far field and degrade imaging performance. In order to specify manufacturing tolerances in terms of performance requirements we must know the connection between the two -- the finish-function relationship. This paper discusses the form of that relationship derived using elementary statistical diffraction theory. It tells us what statistical properties of the surface errors are relevant, it spells out the important role of the system parameters for EUV mirrors which is absent for conventional mirrors, and it leads to simple good-bad tests for mirror quality. These results are an extension of previous work in this area.

The interesting composition of the utility mix in the Chicago region and the potential for electric vehicle use in that area make it an interesting candidate for emissions sensitivity and scenario studies. However, it is difficult to apply the Urban Airshed Model (UAM) to the Chicago region because of the complex meteorology associated with Lake Michigan. The Lake Michigan Air Directors consortium (LADCO) has developed, at considerable expense, an improved version with nested grids and embedded plumes (UAM-V) for application in the Lake Michigan Ozone Study (LMOS) and for regulatory use. The complexity of the LMOS modeling system makes it costly and time-consuming to implement. In this study, the authors apply UAM-IV (US Environmental Protection, 1990a) in its simple ``PLANR (Practice for Low-cost Application in Nonattainment Regions)`` mode (US Environmental Protect Agency, 1990b) to the Chicago region to study various interesting scenarios in a rapid and low-cost manner. The details of the data sets, methods and results of this study are contained in Fernau et al. and are summarized here. In addition, the authors comment on the usefulness of this type of limited-data study as compared to more complex modeling systems and data inputs.

The Gas Turbine-Modular Helium Reactor (GT-MHR) is the result of coupling the evolution of a low power density passively safe modular reactor with key technology developments in the U.S. during the last decade: large industrial gas turbines; large active magnetic bearings; and compact, highly effective plate-fin heat exchangers. This is accomplished through the unique use of the Brayton cycle to produce electricity with the helium as primary coolant from the reactor directly driving the gas turbine electrical generator. This cycle can achieve a high net efficiency in the range of 45% to 48%. In the design of the GT-MHR the desirable inherent characteristics of the inert helium coolant, graphite core, and the coated fuel particles are supplemented with specific design features such as passive heat removal to achieve the safety objective of not disturbing the normal day-to-day activities of the public even for beyond design basis rare accidents. Each GT-MHR plant consists of four modules. The GT-MHR module components are contained within steel pressure vessels: a reactor vessel, a power conversion vessel, and a connecting cross vessel. All vessels are sited underground in a concrete silo, which serves as an independent vented low pressure containment structure. By capitalizing on industrial …

In an effort to reduce the cycle time for producing prototypical mechanical and electro-mechanical components, Sandia National Laboratories has integrated rapid prototyping processes into the design and manufacturing process. The processes currently in operation within the Rapid Prototyping Laboratory are Stereolithography (SL), Selective Laser Sintering (SLS), and Direct Shell Production Casting (DSPC). These emerging technologies have proven to be valuable tools for reducing lead times and fabrication costs. Sandia uses the SL and SLS processes to support internal product development efforts. Their primary use is to fabricate patterns for investment casting in support of a Sandia-managed program called FASTCAST that integrates computational technologies and experimental data into the investment casting process. These processes are also used in the design iteration process to produce proof-of-concept models, hands-on models for design reviews, fit-check models, visual aids for manufacturing, and functional parts in assemblies. The DSPC process is currently being developed as a method of fabricating ceramic investment casting molds directly from a CAD solid model. Sandia is an Alpha machine test site for this process. This presentation will provide an overview of the SL and SLS processes and an update of our experience and success in integrating these technologies into the product …

Preliminary results from the MILC Collaboration for f{sub B}, f{sub B{sub s}}, f{sub D}, f{sub D{sub s}} and their ratios are presented. We compute in the quenched approximation at {beta} = 6.3, 6.0 and 5.7 with Wilson light quarks and static and Wilson heavy quarks. We attempt to quantify all systematic errors other than quenching.

The Computer Hardware, Advanced Mathematics and Model Physics (CHAMMP) program seeks to provide climate researchers with an advanced modeling capability for the study of global change issues. One of the more ambitious projects being undertaken in the CHAMMP program is the development of PCCM2, an adaptation of the Community Climate Model (CCM2) for scalable parallel computers. PCCM2 uses a message-passing, domain-decomposition approach, in which each processor is allocated responsibility for computation on one part of the computational grid, and messages are generated to communicate data between processors. Much of the research effort associated with development of a parallel code of this sort is concerned with identifying efficient decomposition and communication strategies. In PCCM2, this task is complicated by the need to support both semi-Lagrangian transport and spectral transport. Load balancing and parallel I/O techniques are also required. In this paper, the authors review the various parallel algorithms used in PCCM2 and the work done to arrive at a validated model.

The present research reports on the effect of initial mixture temperature on the experimentally measured detonation cell size for hydrogen-air-steam mixtures. Experimental and theoretical research related to combustion phenomena in hydrogen-air-steam mixtures has been ongoing for many years. However, detonation cell size data currently exists or hydrogen-air-steam mixtures up to a temperature of only 400K. Sever accident scenarios have been identified for light water reactors (LWRs) where hydrogen-air mixture temperatures in excess of 400K could be generated within containment. The experiments in this report focus on extending the cell size data base for initial mixture temperatures in excess of 400K. The experiments were carried out in a 10-cm inner-diameter, 6.1-m long heated detonation tube with a maximum operating temperature of 700K and spatial temperature uniformity of {plus_minus}14K. Detonation cell size measurements provide clear evidence that the effect of hydrogen-air initial gas mixture temperature, in the range 300K--650K, is to decrease cell size and, hence, to increase the sensitivity of the mixture to undergo detonations. The effect of steam content, at any given temperature, is to increase the cell size and, thereby, to decrease the sensitivity of stoichiometric hydrogen-air mixtures. The hydrogen-air detonability limits for the 10-cm inside-diameter test vessel, based …

This paper describes the utility of soil characterization using electron microscopy to support decontamination efforts of contaminated soil. Soil contaminated with thorium and uranium from the grounds of a nuclear fuel manufacturing facility was subjected to remediation efforts. A light acid leach was able to remove only 30% of the thorium suggesting that the thorium was present in two or more forms. Analytical electron microscopy determined that all of the thorium was present as ThO{sub 2}, but in a bimodal size distribution and occasionally closely associated with other minerals. Electron microscopy was useful in understanding the remediation data and demonstrates the need for characterization of contaminated soils.

Following a brief review of a commonly used general framework for the analysis of radiative corrections and possible new physics, the recent precision results from the SLD/SLC are discussed and used to test the standard electroweak model. In the 1993 SLD/SLC run, the SLD recorded 50,000 Z events produced by the collision of longitudinally polarized electrons on unpolarized positrons at a center-of-mass energy of 91.26 GeV. The luminosity-weighted average polarization of the SLC electron beam was (63.0 {plus_minus} 1.1)%. We measure the left-right cross-section asymmetry in Z boson production, A{sub LR}, to be 0.1628 {plus_minus} 0.0071 (stat) {plus_minus} 0.0028 (syst) which determines the effective weak mixing angle to be sin{sup 2} {theta}{sub W}{sup eff} = 0.2292 {plus_minus} 0.0009 (stat) {plus_minus} 0.0004 (syst). When averaged with our 1992 result, we obtain sin{sup 2} {theta}{sub W}{sup eff} = 0.2294 {plus_minus} 0. 0010. This result differs from analogous LEP results at the level of about 2.5 {sigma}. The world averages of electroweak data are comfortably in agreement with the standard model.

Photonics activities at Sandia National Laboratories (SNL) are founded on a strong materials research program. The advent of the Compound Semiconductor Research Laboratory (CSRL) in 1988, accelerated device and materials research and development. Recently, industrial competitiveness has been added as a major mission of the labs. Photonics projects have expanded towards applications-driven programs requiring device and subsystem prototype deliveries and demonstrations. This evolution has resulted in a full range of photonics programs from materials synthesis and device fabrication to subsystem packaging and test.

The Rocky Flats Plant is pursuing polymer solidification as a viable treatment option for several mixed waste streams that are subject to land disposal restrictions within the Resource Conservation and Recovery Act provisions. Tests completed to date using both surrogate and actual wastes indicate that polyethylene microencapsulation is a viable treatment option for several mixed wastes at the Rocky Flats Plant, including nitrate salts, sludges, and secondary wastes such as ash. Treatability studies conducted on actual salt waste demonstrated that the process is capable of producing waste forms that comply with all applicable regulatory criteria, including the Toxicity Characteristic Leaching Procedure. Tests have also been conducted to evaluate the feasibility of macroencapsulating certain debris wastes in polymers. Several methods and plastics have been tested for macroencapsulation, including post-consumer recycle and regrind polyethylene.

The tremendous range of temperatures and densities spanned by astrophysical plasmas has significant overlap with conditions attainable using high-power laser facilities. These facilities provide an opportunity to create, control, and characterize plasmas in the laboratory that mirror conditions in some of the most important cosmological systems. Moreover, laboratory experiments can enhance astrophysical understanding by focusing on and isolating important physical processes, without necessarily reproducing the exact conditions of the integral system. Basic study of radiative properties, transport phenomena, thermodynamic response and hydrodynamic evolution in plasmas under properly scaled conditions leads both directly and indirectly to improved models of complex astrophysical systems. In this paper, we will discuss opportunities for current and planned highpower lasers to contribute to the study of high-energy astrophysics.

Lead-indium phosphate-lasses exhibit a number of useful properties such as a hi-h index-of-refraction, low preparation temperature and melt viscosity, and good chemical durability. The structure of such a glass (composition in wt.%: 65 PbO, 29 P{sub 2}O{sub 5}, 6 In{sub 2}O{sub 3}) has been investigated by total neutron scattering using the GLAD diffractometer at Argonne`s spallation neutron source IPNS. Peaks corresponding to the P-0, Pb-O/ln-O, and O-O pairs were observed in the radial distribution function. The short-range structure in the -lass, in terms of average coordination numbers and bond distances, is compared with those of a pure P{sub 2}O{sub 5} glass and with the crystal structure of lead pyrophosphate, Pb{sub 2}P{sub 2}O{sub 7}. Unlike silicate glasses in which the SiO{sub 4} tetrahedra form a 3-dimensional network, the PO{sub 4} tetrahedra in phosphate glasses form a chain-like structure. The structural modification by the lead cations in phosphate glasses appears to occur mainly in the medium range-affecting, the lengths and connectivity of the chain-like structure.

Our belief that climate will inexorably change is driven by the very clear evidence of chemical abundance changes in the atmosphere during the last four decades. In the past, this belief has led to the development of two separate efforts: to understand and build models to describing the physical climate system and to understand and build models of the chemical climate system. But how will these two systems interact? Are there important chemical changes that result from climate change that need to be understood and properly accounted for in order to predict the evolution of the climate system? Are there important climate changes that may affect chemical abundances that must be addressed? Large strides have been made in our capability to predict both the physical climate system and the chemical climate system during the past few years. In spite of extant uncertainties in both General Circulation Models (GCMs) and Chemical Transport Models (CTMs), we should begin the process of understanding how and to what extent these errors might propagate in the coupled system. We have outlined a strategy for quantifying the effective uncertainties and have defined a few initial steps in the process. Systematic study of the importance of uncertainties …

We present some essential features of a macroscopic-microscopic nuclear-structure model, with special emphasis on the results of a recent global calculation of nuclear masses. We discuss what should be some minimal requirements of a nuclear mass model and study how the macroscopic-microscopic method and other nuclear mass models fulfil such basic requirements. We study in particular the reliability of nuclear mass models in regions of nuclei that were not considered in the determination of the model parameters.

High-resolution satellite data provide detailed, quantitative descriptions of land surface characteristics over large areas so that objective scale linkage becomes feasible. With the aid of satellite data, Sellers et al. and Wood and Lakshmi examined the linearity of processes scaled up from 30 m to 15 km. If the phenomenon is scale invariant, then the aggregated value of a function or flux is equivalent to the function computed from aggregated values of controlling variables. The linear relation may be realistic for limited land areas having no large surface contrasts to cause significant horizontal exchange. However, for areas with sharp surface contrasts, horizontal exchange and different dynamics in the atmospheric boundary may induce nonlinear interactions, such as at interfaces of land-water, forest-farm land, and irrigated crops-desert steppe. The linear approach, however, represents the simplest scenario, and is useful for developing an effective scheme for incorporating subgrid land surface processes into large-scale models. Our studies focus on coupling satellite data and ground measurements with a satellite-data-driven land surface model to parameterize surface fluxes for large-scale climate models. In this case study, we used surface spectral reflectance data from satellite remote sensing to characterize spatial and temporal changes in vegetation and associated surface …

We present a preliminary measurement of the inclusive production rates of K{sub s}, A and X hadrons produced in e{sup +}e{sup {minus}} annihilation at the Z{sup 0} pole. The analysis is based upon approximately 50K Z{sup 0} decays collected in the SLD experiment at SLAC in 1993. The observed rates of (K{sub s}) = 1.02 {plus_minus} 0.02 {plus_minus} 0.09 and ({Lambda}) + ({bar {Lambda}}) = 0.38 {plus_minus} 0.01 {plus_minus} 0.04 are consistent with previous measurements. Our differential cross section peak-position results are shown to be consistent with QCD predictions based on the modified leading logarithm approximation and local parton-hadron duality.

We present recent results, from a beam test, on the angular dependence of the efficiency and the distribution of the signals on the anode strips of a low-pressure microstrip gas chamber with a thick CsI layer as a secondary-electron emitter. New results of CVD diamond films as secondary-electron emitters are discussed.