Experimental studies of the Li/sup +/ + He interaction have been extended to smaller internuclear separations to clarify a discrepancy between experiment and theory in the elastic cross sections and to observe and measure cross sections for inelastic excitation. For R less than or equal to 0.5 a/sub 0/ the elastic scattering differential cross section is observed to droop far below that expected from a single-state interaction based on ab initio ground-state potentials. In this same region of R both one- and two-electron excitations of He are observed to be strongly excited, and cross sections were measured for each of them. The lowest inelastic channel is an electron-capture state, which is observed indirectly to be strongly populated also. A diabatic correlation diagram is constructed that exhibits the basic interactions responsible for the excitation.

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The present invention is directed to a novel neutron and gamma radiation shielding material consisting of 95 to 97% by weight SiO/sub 2/ and 5 to 3% by weight sodium silicate. In addition, the method of using this composition to provide a continuous neutron and gamma radiation shielding structure is disclosed.

The extraction of information from measured or computed data is all-pervasive; to gain the most value from extracted information, it must often be transformed from one type of data into another, a process that can only preserve or lose information. An information-transformation process based upon Prony's method was found to be increasingly useful for application to electromagnetic-type problems in particular and a growing variety of physical problems in general. This procedure allows the coefficients and exponents (or parameters) of an exponential series to be derived from a sequence of its sampled values. Two basic issues are associated with Prony processing: determination of the status of the input data and application of the procedure as effectively as possible to maximize the information content of the output. The possible uses of the Prony method as an information on-transformation process are discussed; the insight gained from this viewpoint concerning the information content of data is emphasized. Waveform and spectrum characterization, data compression, and inversion of pattern data are considered briefly as applications. 8 figures, 3 tables. (RWR)

Clostridium botulinum is a taxonomic designation for many diverse anaerobic spore forming rod-shaped bacteria which have the common property of producing botulinum neurotoxins (BoNTs). The BoNTs are exoneurotoxins that can cause severe paralysis and even death in humans and various other animal species. A collection of 174 C. botulinum strains were examined by amplified fragment length polymorphism (AFLP) analysis and by sequencing of the 16S rRNA gene and BoNT genes to examine genetic diversity within this species. This collection contained representatives of each of the seven different serotypes of botulinum neurotoxins (BoNT A-G). Analysis of the16S rRNA sequences confirmed earlier reports of at least four distinct genomic backgrounds (Groups I-IV) each of which has independently acquired one or more BoNT serotypes through horizontal gene transfer. AFLP analysis provided higher resolution, and can be used to further subdivide the four groups into sub-groups. Sequencing of the BoNT genes from serotypes A, B and E in multiple strains confirmed significant sequence variation within each serotype. Four distinct lineages within each of the BoNT A and B serotypes, and five distinct lineages of serotype E strains were identified. The nucleotide sequences of the seven serotypes of BoNT were compared and show varying degrees …

This account of the beginning of the program on laser fusion at Livermore in 1962, and its subsequent development during the decade ending in 1972, was originally prepared as a contribution to the January 1991 symposium 'Achievements in Physics' honoring Professor Keith Brueckner upon his retirement from the University of San Diego at La Jolla. It is a personal recollection of work at Livermore from my vantage point as its scientific leader, and of events elsewhere that I thought significant. This period was one of rapid growth in which the technology of high-power short-pulse lasers needed to drive the implosion of thermonuclear fuel to the temperature and density needed for ignition was developed, and in which the physics of the interaction of intense light with plasmas was explored both theoretically and experimentally.

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The measurement of regional attenuation Q{sup -1} can produce method dependent results. The discrepancies among methods are due to differing parameterizations (e.g., geometrical spreading rates), employed datasets (e.g., choice of path lengths and sources), and methodologies themselves (e.g., measurement in the frequency or time domain). We apply the coda normalization (CN), two-station (TS), reverse two-station (RTS), source-pair/receiver-pair (SPRP), and the new coda-source normalization (CS) methods to measure Q of the regional phase, Lg (Q{sub Lg}), and its power-law dependence on frequency of the form Q{sub 0}f{sup {eta}} with controlled parameterization in the well-studied region of northern California using a high-quality dataset from the Berkeley Digital Seismic Network. We test the sensitivity of each method to changes in geometrical spreading, Lg frequency bandwidth, the distance range of data, and the Lg measurement window. For a given method, there are significant differences in the power-law parameters, Q{sub 0} and {eta}, due to perturbations in the parameterization when evaluated using a conservative pairwise comparison. The CN method is affected most by changes in the distance range, which is most probably due to its fixed coda measurement window. Since, the CS method is best used to calculate the total path attenuation, it is very …

Using a regional time-domain waveform inversion for the complete moment tensor we calculate the deviatoric and isotropic source components for several explosions at the Nevada Test Site as well as earthquakes, and collapses in the surrounding region of the western US. The events separate into specific populations according to their deviation from a pure double-couple and ratio of isotropic to deviatoric energy. The separation allows for anomalous event identification and discrimination between explosions, earthquakes, and collapses. Error in the moment tensor solutions and source parameters is also calculated. We investigate the sensitivity of the moment tensor solutions to Green's functions calculated with imperfect Earth models, inaccurate event locations, and data with a low signal-to-noise ratio. We also test the performance of the method under a range of recording conditions from excellent azimuthal coverage to cases of sparse station availability, as might be expected for smaller events. Finally, we assess the depth and frequency dependence upon event size. This analysis will be used to determine the range where well-constrained solutions can be obtained.

Gas storage is a critical element in the natural gas industry. Producers, transmission & distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services, and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet (TCF) over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is critical in meeting the needs of these new markets. In order to address the gas storage needs of the natural gas industry, an industry-driven consortium was created--the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance operational flexibility and deliverability of the Nation's gas storage system, and provide a …

This report describes a cold mass support system based on the use of oriented fiberglassepoxy rods in bending.

A double-windowed vacuum-tight experimental chamber was developed, and calibrated on the spectroscopic ellipsometer over the energy range from .7 to 4.5 eV using a silicon wafer with approximately 25 nm oxide thickness to remove the multiple-window effects from measurements. The ellipsometric measurements were done such that incident and exit beam were at 65 degree from surface normal. The plutonium sample (3 mm diameter, .1 mm thick) was electro-polished and mounted into the sample chamber in a glove box having a nitrogen atmosphere with less than 100ppm moisture and oxygen content. The index of refraction n and the extinction coefficient k decrease from 3.7 to 1 and 5.5 to 1.1 respectively as the photon energy increases from .7 to 4.3 eV.

Genomic comparisons between human and distant, non-primatemammals are commonly used to identify cis-regulatory elements based onconstrained sequence evolution. However, these methods fail to detect"cryptic" functional elements, which are too weakly conserved amongmammals to distinguish from nonfunctional DNA. To address this problem,we explored the potential of deep intra-primate sequence comparisons. Wesequenced the orthologs of 558 kb of human genomic sequence, coveringmultiple loci involved in cholesterol homeostasis, in 6 nonhumanprimates. Our analysis identified 6 noncoding DNA elements displayingsignificant conservation among primates, but undetectable in more distantcomparisons. In vitro and in vivo tests revealed that at least three ofthese 6 elements have regulatory function. Notably, the mouse orthologsof these three functional human sequences had regulatory activity despitetheir lack of significant sequence conservation, indicating that they arecryptic ancestral cis-regulatory elements. These regulatory elementscould still be detected in a smaller set of three primate speciesincluding human, rhesus and marmoset. Since the human and rhesus genomesequences are already available, and the marmoset genome is activelybeing sequenced, the primate-specific conservation analysis describedhere can be applied in the near future on a whole-genome scale, tocomplement the annotation provided by more distant speciescomparisons.

Recent experiments on double photoionization of H$_2$ with photon energies between 160 and 240 eV have revealed body-frame angular distributions that suggest classical two-slit interference effects may be present when one electron carries most of the available energy and the second electron is not observed. We report precise quantum mechanical calculations that reproduce the experimental findings. They reveal that the interpretation in terms of classical diffraction is only appropriate atsubstantially higher photon energies. At the energies considered in the experiment we offer an alternative explanation based on the mixing of two non-diffractive contributions by circularly polarized light.

The National Nuclear Security Administration (NNSA) Ground-Based Nuclear Explosion Monitoring Research and Engineering (GNEM R&E) Program at LLNL has made significant progress enhancing the process of deriving seismic calibrations and performing scientific integration, analysis, and information management with software automation tools. Several achievements in schema design, data visualization, synthesis, and analysis were completed this year. Our tool efforts address the problematic issues of very large datasets and varied formats encountered during seismic calibration research. As data volumes have increased, scientific information management issues such as data quality assessment, ontology mapping, and metadata collection that are essential for production and validation of derived calibrations have negatively impacted researchers abilities to produce products. New information management and analysis tools have resulted in demonstrated gains in efficiency of producing scientific data products and improved accuracy of derived seismic calibrations. Significant software engineering and development efforts have produced an object-oriented framework that provides database centric coordination between scientific tools, users, and data. Nearly a half billion parameters, signals, measurements, and metadata entries are all stored in a relational database accessed by an extensive object-oriented multi-technology software framework that includes elements of stored procedures, real-time transactional database triggers and constraints, as well as coupled Java …

We measure the time to explosion of 12.7 mm diameter spheres of ultra fine TATB and PBX-9502 (95 wt% TATB, 5 wt% Kel-F 800) at 85.0, 92.5, and 98.0 percent of theoretical maximum density (TMD) in confined and unconfined configurations and at several elevated temperatures with the Lawrence Livermore National Laboratory (LLNL) One Dimensional Time to Explosion (ODTX) apparatus. Time to explosion data provide insight into the relative ease of thermal ignition and allow for the calibration of kinetic parameters. The measurements show that PBX-9502 is more thermally stable than ultra fine TATB, that unconfined samples are slightly more thermally stable than confined ones, and that lower density samples are more thermally stable than higher density ones. 'Go/no go' data at the lowest temperatures yield an experimental measurement of the critical temperature, which is the temperature at which an explosive can be heated indefinitely without undergoing self-heating and concomitant rapid and violent decomposition. Critical temperatures ranges for 12.7 mm diameter spheres of 98% TMD ultra fine TATB and PBX-9502 are 213-230 C and 234-239 C, respectively. Experimental data are modeled with ALE3D and kinetic parameters are determined. These kinetic parameters, when coupled with thermal property data, provide good prediction of …

This review article surveys recent work on computer representation of molecular surfaces. Several different algorithms are discussed for producing vector or raster drawings of space-filling models formed as the union of spheres. Other smoother surfaces are also considered.

Recent Supreme Court decisions, which interpret the 200-year-old Fourth Amendment of the US Constitution, are used to provide a brief overview of some search and seizure subjects important to management and officers responsible for physical protection of nuclear facilities. The overview is framed in practical terms in order to make the comments applicable to the everyday activity of nuclear-protective-force persons. The Supreme Court has described several exceptions where searches and seizures (arrests) are permitted without a warrant, despite the Fourth Amendment which states that warrants are always required. The seven exceptions briefly discussed are search incidents to a lawful arrest, the automobile-search exception, the suitcase or container exception, the hot-pursuit or emergency exception, the stop-and-frisk exception, the plain-view exception, and consent to be searched.

A method has been developed for fabricating uranium carbide/beryllium carbide/graphite fuel-element specimens for reactor-core-meltdown studies. The method involves milling and blending the raw materials and densifying the resulting blend by conventional graphite-die hot-pressing techniques. It can be used to fabricate specimens with good physical integrity and material dispersion, with densities of greater than 90% of the theoretical density, and with a uranium carbide particle size of less than 10 ..mu..m.

The steam-driven GKSS pressure suppression test facility, which contains 3 full scale vent pipes, has been used for 5 years to investigate the postulated loss-of-coolant accident in a Mark II and Type 69 boiling water reactor. Using the results from several of these tests, wetwell boundary load data (peak pressures and spectral power) during the chugging stage, have been evaluated for sparse pool response (one and two vents in the three vent pool) and for full pool response (one, two, or three vent operation in pools of constant wetwell pool area per vent). The sparse pool results indicate the pool-system, chug event boundary loads are strongly dependent on wetwell pool area per vent, with the load increasing with decreasing area. The full pool results show a substantial increase in the pool-system, chug event boundary loads upon a change from single cell to double cell operation; only minor change occurs in going from double to triple cell operation.

In February 1991, Reactor Materials increased the rate of supernate treatment in the M-Area Dilute Effluent Treatment Facility (DETF) from 1800 gallons to [approximately]2700 gallons of supernate per 36,000 gallon dilute wastewater batch. The first release of the treated effluent began on March 3, 1991. A series of whole effluent toxicity tests was conducted on the DETF effluent to determine if the increased supernate concentration would result in any chronic toxicity affects in the receiving stream (Tims Branch). The toxicity tests were conducted at instream concentrations equivalent to DETF release rates of 5, 10, 15, 20, and 25 gallons/min. The test results, based on 7-day Ceriodaphnia dubia chronic toxicity, indicated no toxicity effects at any concentration tested. Supernate treatment in DETF continued at the higher concentration.

This document discusses a support provided for use in a thermionic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end is supported by a spring structure that includes a pair of Belleville springs, and the spring structure is supported by a support structure fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element at the front end, a larger metal main support at the rear end that is attached to the housing, and with a ceramic layer between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer captured between the Belleville springs. 7 figs.

This report is made up of slides presented at the briefing on recommendations for the incorporation of MOPPS-like detail into the BNL/DRI model. Major subjects are: fundamental purpose of energy planning; ERDA planning; hierarchical framework of production functions/models; recommendation; and management plan for implementation of recommendation. (MCW)

The 242-A Evaporator is the primary waste evaporator for the Hanford Site radioactive liquid waste stored in underground double-shell tanks. Low pressure evaporation is used to remove water from the waste, thus reducing the amount of tank space required for storage. The process produces a concentrated slurry, a process condensate, and an offgas. The offgas exhausts through two stages of high-efficiency particulate air (HEPA) filters before being discharged to the atmosphere 40 CFR 61 Subpart H requires assessment of the unfiltered exhaust to determine if continuous compliant sampling is required. Because potential (unfiltered) emissions are not measured, methods have been developed to estimate these emissions. One of the methods accepted by the Environmental Protection Agency is the measurement of the accumulation of radionuclides on the HEPA filters. Nondestructive assay (NDA) was selected for determining the accumulation on the HEPA filters. NDA was performed on the HEPA filters before and after a campaign in 1997. NDA results indicate that 2.1 E+4 becquerels of cesium-137 were accumulated on the primary HEPA 1700 filter during the campaign. The feed material processed in the campaign contained a total of 1.4 E+l6 Bq of cesium-137. The release factor for the evaporator process is 1.5 E-12. …