505 Matching Results

Results open in a new window/tab.

Disilene Addition to C{sub 70} (open access)

Disilene Addition to C{sub 70}

Semiempirical and ab initio Hartree Fock computational results indicate that the highly reactive dienophile tetramethyldisilene, Me{sub 2}Si=SiMe{sub 2}, is an excellent candidate for a novel functionalization of the equator of C{sub 70} via a [2+4] cycloaddition to the 21, 22, 23, 42 carbons. Thermal or photochemical generation of tetramethyldisilene in the presence of C{sub 70} results in similar complex mixtures in which the major product appears to be that of [2+2] cycloaddition to the 7,8 carbons of C{sub 70}. A minor product clearly results from [2+2] cycloaddition to the 1,9 carbons. Both of these products are hydrolytically unstable and are converted nonspecifically to mixtures of 1,9- and 7,8-C{sub 70}H{sub 2} which are also present in HPLC traces of the reaction mixtures.
Date: December 31, 1994
Creator: Jacobs, S. J.; Cahill, P. A. & Rohlfing, C. M.
System: The UNT Digital Library
Flat panel display development activities at Sandia National Laboratories (open access)

Flat panel display development activities at Sandia National Laboratories

The flat panel display development activities underway at Sandia National Laboratories are described. Research is being conducted in the areas of glass substrates, phosphors, large area processes, and electron emissions. Projects are focused on improving process yield, developing large area processes, and using modeling techniques to predict design performance.
Date: December 31, 1994
Creator: DiBello, E. G.; Worobey, W.; Burchett, S.; Hareland, W.; Felter, T. & Mays, B.
System: The UNT Digital Library
The role of the LLNL Atmospheric Release Advisory Capability in a FRMAC response to a nuclear power plant incident (open access)

The role of the LLNL Atmospheric Release Advisory Capability in a FRMAC response to a nuclear power plant incident

The Federal Radiological Emergency Response Plan (FRERP) can provide several emergency response resources in response to a nuclear power plant (NPP) accident if requested by a state or local agency. The primary FRERP technical resources come from the US Department of Energy`s (DOE) Federal Radiological Monitoring and Assessment Center (FRMAC). Most of the FRMAC assets are located at the DOE Remote Sensing Laboratory (RSL) at Nellis Air Force Base, Las Vegas, Nevada. In addition, the primary atmospheric dispersion modeling and dose assessment asset, the Atmospheric Release Advisory Capability (ARAC) is located at Lawrence Livermore National Laboratory (LLNL) in Livermore, California. In the early stages of a response, ARAC relies on its automatic worldwide meteorological data acquisition via the Air Force Global Weather Center (AFGWC). The regional airport data are supplemented with data from on-site towers and sodars and the National Oceanographic & Atmospheric Administration`s (NOAA) field-deployable real-time rawinsonde system. ARAC is prepared with three-dimensional regional-scale diagnostic dispersion model to simulate the complex mixed fission product release from a reactor accident. The program has been operational for 18 years and is presently developing its third generation system. The current modernization includes faster central computers, a new site workstation system. The current …
Date: December 31, 1994
Creator: Baskett, R. L.; Sullivan, T. J.; Ellis, J. S. & Foster, C. S.
System: The UNT Digital Library
Study of parity and time reversal violation in neutron-nucleus interactions (open access)

Study of parity and time reversal violation in neutron-nucleus interactions

The parity and time-reversal symmetries can be studies in neutron-nucleus interactions. Parity non-conserving asymmetries have been observed for many p-wave resonances in a compound nucleus and measurements were performed on several nuclei in the mass region of A{approximately}100 and A{approximately}230. The statistical model of the compound nucleus provides a theoretical basis for extracting mean-squared matrix elements from the experimental asymmetry data, and for interpreting the mean-squared matrix elements. The constraints on the weak meson-exchange couplings calculated from the compound-nucleus asymmetry data agree qualitatively with the results from few-body and light-nuclei experiments. The tests of time-reversal invariance in various experiments using thermal, epithermal and MeV neutrons are being developed.
Date: December 31, 1994
Creator: Yen, Yi-Fen; Bowman, J. D.; Frankle, C. M. & Crawford, B. E.
System: The UNT Digital Library
Manufacture and testing of the superconducting wire and cable for the RHIC dipoles and quadrupoles (open access)

Manufacture and testing of the superconducting wire and cable for the RHIC dipoles and quadrupoles

Production of superconducting wire and cable for RHIC dipoles and quadrupoles is now complete. This report presents final statistics generated during the manufacture and testing of this cable.
Date: December 31, 1994
Creator: Greene, A. F.; Garber, M. G.; Ghosh, A. K.; McChesney, D.; Morgillo, A.; Shah, R. et al.
System: The UNT Digital Library
Accelerator-based systems for plutonium destruction and nuclear waste transmutation (open access)

Accelerator-based systems for plutonium destruction and nuclear waste transmutation

Accelerator-base systems are described that can eliminate long-lived nuclear materials. The impact of these systems on global issues relating to plutonium minimization and nuclear waste disposal can be significant. An overview of the components that comprise these systems is given, along with discussion of technology development status and needs. A technology development plan is presented with emphasis on first steps that would demonstrate technical performance.
Date: December 31, 1994
Creator: Arthur, E. D.
System: The UNT Digital Library
Gamma-ray measurements at the WNR white neutron source (open access)

Gamma-ray measurements at the WNR white neutron source

Photon production data have been acquired in the incident neutron energy range, 1 < E{sub n} < 400 MeV, for a number of target nuclei, gamma-ray energy ranges, and reactions, using the continuous-energy neutron beam of the WNR facility at Los Alamos. Gamma-ray production measurements using high resolution Ge detectors have been employed for gamma-rays in the energy range, 0.1 < E{sub {gamma}} < 10 MeV. These measurements allow identification of reactions from the known energies of the gamma-ray transitions between low-lying states in the final nucleus. Some of the targets studied include: N, O, Al, Na, {sup 56}Fe, and {sup 207,208}Pb. These data are useful both for testing nuclear reaction models at intermediate energies and for numerous applied purposes. BGO detectors do not have the good energy resolution of Ge detectors, but have much greater detection efficiency for gamma rays with energies greater than a few MeV. We have used an array of 5 BGO detectors to measure cross sections and angular distributions for photon production from C and N. A large, well-shielded BGO detector has been used to measure fast neutron capture in the giant resonance region with a maximum gamma-ray energy of 52 MeV. We present results …
Date: December 31, 1994
Creator: Nelson, R. O.; Wender, S. A. & Mayo, D. R.
System: The UNT Digital Library
Proceedings of the workshop on future hadron facilities in the US (open access)

Proceedings of the workshop on future hadron facilities in the US

This report discusses the following topics on future hadron facilities: Workshop on future hadron facilities in the US; 30 {times} 30 TeV-summary report; A high luminosity, 2 {times} 2 TeV collider in the tevatron tunnel; magnets working group; cryogenics discussion; vacuum report; antiproton source production; injector working group; interaction region working group; lattice/beam dynamics working group; LEBT for high-luminosity colliders; some notes on long-range beam-beam effects for the 2TeV collider; synchrotron radiation masks for high energy proton accelerators. Emittance preservation in a proton synchrotron; beam-beam interaction effects on betatron tunes; analytic solutions for phase trombone modules; and chromatic corrections of RHIC when one or two insertions is at {Beta}* = 0.5m.
Date: December 31, 1994
Creator: unknown
System: The UNT Digital Library
Optical properties of fractal nanocomposites (open access)

Optical properties of fractal nanocomposites

Optical prossesses in nanostructured fractal composites are shown to be strongly enhanced. The enhancement occurs because of a localization of dipolar eigenmodes in subwavelength areas.
Date: December 31, 1994
Creator: Markel, V. A.; Kim, W.; Armstrong, R.; Shalaev, V. & Stechel, E. B.
System: The UNT Digital Library
Buried Waste Integrated Demonstration lessons learned: 1993 technology demonstrations (open access)

Buried Waste Integrated Demonstration lessons learned: 1993 technology demonstrations

An integrated technology demonstration was conducted by the Buried Waste Integrated Demonstration (BWID) at the Idaho National Engineering Laboratory Cold Test Pit in the summer of 1993. This program and demonstration was sponsored by the US Department of Energy Office of Technology Development. The demonstration included six technologies representing a synergistic system for the characterization and retrieval of a buried hazardous waste site. The integrated technology demonstration proved very successful and a summary of the technical accomplishments is presented. Upon completion of the integrated technology demonstration, cognizant program personnel participated in a lessons learned exercise. This exercise was conducted at the Simplot Decision Support Center at Idaho State University and lessons learned activity captured additional information relative to the integration of technologies for demonstration purposes. This information will be used by BWID to enhance program planning and strengthen future technology demonstrations.
Date: December 31, 1994
Creator: Kostelnik, K. M. & Owens, K. J.
System: The UNT Digital Library
Status of nuclear data for ITER applications (open access)

Status of nuclear data for ITER applications

As the development of a near-term fusion reactor, such as the International Thermonuclear Experimental Reactor (ITER), enters the engineering design activity phase, one of the essential elements leading to the successful design, construction and operation of such a reactor is nuclear data. High quality nuclear data for all reactor materials relevant to ITER will be required in order to assess the nuclear performance, radiation damage, and safety and environmental aspects of all reactor components. In this paper the authors review the current ITER design, noting which materials and associated nuclear data are important in the various reactor components. They also review the contents of the Fusion Evaluated Nuclear Data Library (FENDL) accepted for use by ITER, and identify materials for which nuclear data improvements are required.
Date: December 31, 1994
Creator: Larson, D. C.; Cheng, E. T.; Mann, F. M. & Saji, G.
System: The UNT Digital Library
Long-Baseline Neutrino Oscillation Experiments (open access)

Long-Baseline Neutrino Oscillation Experiments

There is no unambiguous definition for long baseline neutrino oscillation experiments. The term is generally used for accelerator neutrino oscillation experiments which are sensitive to {Delta}m{sup 2} < 1.0 eV{sup 2}, and for which the detector is not on the accelerator site. The Snowmass N2L working group met to discuss the issues facing such experiments. The Fermilab Program Advisory Committee adopted several recommendations concerning the Fermilab neutrino program at their Aspen meeting immediately prior to the Snowmass Workshop. This heightened the attention for the proposals to use Fermilab for a long-baseline neutrino experiment at the workshop. The plan for a neutrino oscillation program at Brookhaven was also thoroughly discussed. Opportunities at CERN were considered, particularly the use of detectors at the Gran Sasso laboratory. The idea to build a neutrino beam from KEK towards Superkamiokande was not discussed at the Snowmass meeting, but there has been considerable development of this idea since then. Brookhaven and KEK would use low energy neutrino beams, while FNAL and CERN would plan have medium energy beams. This report will summarize a few topics common to LBL proposals and attempt to give a snapshot of where things stand in this fast developing field.
Date: December 31, 1994
Creator: Crane, Dan & Goodman, Maury
System: The UNT Digital Library
The hard truth (open access)

The hard truth

In the Bayesian methodology, the posterior probability combines uncertainty about prior knowledge, and available data about alternative models of reality. The posterior quantifies the degree of certainty one has in inferring the truth in terms of those models. We propose a method to determine the reliability of a specific feature of a Bayesian solution. Our approach is based on an analogy between the negative logarithm of the posterior and a physical potential. This analogy leads to the interpretation of gradient of this potential as a force that acts on the model. As model parameters are perturbed from their maximum a posteriori (MAP) values, the strength of the restoring force that drives them back to the MAP solution is directly related to the reliability of those parameter estimates. The correlations between the uncertainties of parameter estimates can be elucidated.
Date: December 31, 1994
Creator: Hanson, K. M. & Cunningham, C. S.
System: The UNT Digital Library
High surface area, high permeability carbon monoliths (open access)

High surface area, high permeability carbon monoliths

The goal of this work is to prepare carbon monoliths having precisely tailored pore size distribution. Prior studies have demonstrated that poly(acrylonitrile) can be processed into a precursor having tailored macropore structure. Since the macropores were preserved during pyrolysis, this synthetic process provided a route to porous carbon having macropores with size =0.1 to 10{mu}m. No micropores of size <2 nm could be detected in the carbon, however, by nitrogen adsorption. In the present work, the authors have processed a different polymer, poly(vinylidene chloride) into a macroporous precursor, Pyrolysis produced carbon monoliths having macropores derived from the polymer precursor as well as extensive microporosity produced during the pyrolysis of the polymer. One of these carbons had BET surface area of 1,050 m{sup 2}/g and about 1.2 cc/g total pore volume, with about 1/3 of the total pore volume in micropores and the remainder in 1{mu}m macropores. No mesopores in the intermediate size range could be detected by nitrogen adsorption. Carbon materials having high surface area as well as micron size pores have potential applications as electrodes for double layer supercapacitors containing liquid electrolyte, or as efficient media for performing chemical separations.
Date: December 31, 1994
Creator: Lagasse, R. R. & Schroeder, J. L.
System: The UNT Digital Library
Tau as a probe for new physics (open access)

Tau as a probe for new physics

The usage of polarimetry and spin-correlation tests to determine the complete Lorenz structure of the tau lepton`s charged and neutral- current couplings is reviewed. The emphasis is on tests for ``something`` in a (V-A)+ ``something`` structure in J{sup charged} Lepton current, so as to bound the scales {lambda} for ``new physics`` such as arising from tau weak magnetism, weak electricity, and/or second-class currents. Tests for T and for CP violation are discussed.
Date: December 31, 1994
Creator: Nelson, C. A.
System: The UNT Digital Library
Probing anomalous gauge boson couplings at LEP (open access)

Probing anomalous gauge boson couplings at LEP

We bound anomalous gauge boson couplings using LEP data for the Z {yields} {bar {integral}}{integral} partial widths. We use an effective field theory formalism to compute the one-loop corrections resulting from non-standard model three and four gauge boson vertices. We find that measurements at LEP constrain the three gauge boson couplings at a level comparable to that obtainable at LEPII.
Date: December 31, 1994
Creator: Dawson, S. & Valencia, G.
System: The UNT Digital Library
Computer simulation and capacity evaluation of Panama Canal alternatives (open access)

Computer simulation and capacity evaluation of Panama Canal alternatives

The Operating Characteristics and Capacity Evaluation (OCCE) Study was one of the components of a group of studies of future alternatives to the Panama Canal, sponsored by a study commission formed by the governments of Panama, the US and Japan. The basic tool in the conduct of the study was the Waterway Analysis Model (WAM), developed originally by the US Army Corps of Engineers for use on the US inland waterway system and adapted under OCCE for study of Panama Canal alternatives. The study synthesized the many alternative plans for the Canal proposed historically into four basic groups: High-Rise Lock Canal, Low-Rise Lock Canal, Sea-Level Canal and Status Quo Canal. For economy, the sea-level cases were based on, essentially, a single-lane canal, in conjunction with the status quo canal. Hydraulic and navigation studies indicted that to achieve safe navigation, tide gates or locks would be required to control currents that would otherwise be generated by the differences in tides between the two oceans. The alternatives studied in detail are illustrated in the body of the paper.
Date: December 31, 1994
Creator: Rosselli, A. T.; Bronzini, M. S. & Weekly, D. A.
System: The UNT Digital Library
The stainless steel beneficial reuse integrated demonstration (open access)

The stainless steel beneficial reuse integrated demonstration

Process water heat exchangers at SRS contains over 95% 304 stainless steel which could be recycled back to DOE in a ``controlled release`` manner, that is, the radioactive scrap metal (RSM) could be reprocessed into new reusable products for return to DOE for use within the DOE Complex. In 1994, a demonstration was begun to recycle recycle contaminated stainless steel by melting 60 tons of RSM and refabricating it into containers for long-term temporary storage. The demonstration covers the entire recycle chain; the melting and the fabrication are to be done through subcontracts with private industry. Activity level of RSM to be supplied to industry is less than one curie total; the average specific activity level of the cobalt-60 which will be imbedded in the final products was estimated to be 117 pico curies per gram (4.31 becquerels/gram).
Date: December 31, 1994
Creator: Boettinger, W. L. & Lutz, R. N.
System: The UNT Digital Library
Electromagnetic production of pions on the nucleon (open access)

Electromagnetic production of pions on the nucleon

The objective of this talk is to review the recent theoretical developments in the study of photo- and electro-production of pions on the nucleon. First, the author will discuss the results from the investigations in the near threshold region. The focus here is the test of pion dynamics as predicted by the theoretical models with chiral symmetry. The second subject of this talk is concerned with the deformation of the Delta ({Delta}) state. The central question here is how this interesting quantity is defined theoretically and related to the experiments being performed at MIT-Bates and Mainz. The author then will discuss briefly the higher energy region where the productions of higher mass nucleon resonances (N*) and two-pion states become important. The interest here is the test of {gamma}N {yields} N* matrix elements as predicted by various QCD-based models of hadrons.
Date: December 31, 1994
Creator: Lee, T. S. H.
System: The UNT Digital Library
Aspects of macroscopic phase separation and interstitial oxygen ordering in oxygen doped La{sub 2}CuO{sub 4+{delta}} (open access)

Aspects of macroscopic phase separation and interstitial oxygen ordering in oxygen doped La{sub 2}CuO{sub 4+{delta}}

NMR and neutron diffraction measurements reveal that macroscopic phase separation and the tetragonal to orthorhombic (TO) structural phase coincide at two distinct points in the temperature-doping phase plot for oxygen doped La{sub 2}CuO{sub 4+{delta}}. Thus the TO phase line coincides with the phase separation line. This is evidence that the macroscopic phase separation is inhibited in the tetragonal phase. We propose that the interstitial oxygen has higher mobility in the orthorhombic phase and that insufficient mobility suppresses macroscopic phase separation in the tetragonal phase. Neutron diffraction measurements also reveal superlattice peaks which indicate ordering of the interstitial oxygen. Our NMR measurements, have demonstrated a distribution of tilts of the CuO{sub 6} octahedra. We propose a sawtooth modulation of the octahedral tilt in which the sign of the tilt changes when the tilt reaches a maximum value can explain this distribution. The large openings in the La-O layer resulting from the abrupt switch of the sign of the tilt provide an attractive location for the interstitial oxygen. This mechanism would lead to stripe ordering of the interstitial oxygen.
Date: December 31, 1994
Creator: Hammel, P. C.; Fisk, Z.; Statt, B. W.; Chou, F. C.; Johnston, D. C.; Cheong, S. W. et al.
System: The UNT Digital Library
The effect on stability and thermal hydraulic quenchback of perforating the jacket of a cable-in-conduit conductor (open access)

The effect on stability and thermal hydraulic quenchback of perforating the jacket of a cable-in-conduit conductor

This Paper continues earlier work on the reduction of the quench pressure in a doubler cable-in-conduit conductor achieved by perforating the inner jacket. The present study examines the effect of the perforations on the stability margin and on the onset of thermal hydraulic quenchback.
Date: December 31, 1994
Creator: Dresner, L.
System: The UNT Digital Library
Atmospheric and dispersion modeling in areas of highly complex terrain employing a four-dimensional data assimilation technique (open access)

Atmospheric and dispersion modeling in areas of highly complex terrain employing a four-dimensional data assimilation technique

The results of this study indicate that the current data assimilation technique can have a positive impact on the mesoscale flow fields; however, care must be taken in its application to grids of relatively fine horizontal resolution. Continuous FDDA is a useful tool in producing high-resolution mesoscale analysis fields that can be used to (1) create a better initial conditions for mesoscale atmospheric models and (2) drive transport models for dispersion studies. While RAMS is capable of predicting the qualitative flow during this evening, additional experiments need to be performed to improve the prognostic forecasts made by RAMS and refine the FDDA procedure so that the overall errors are reduced even further. Despite the fact that a great deal of computational time is necessary in executing RAMS and LPDM in the configuration employed in this study, recent advances in workstations is making applications such as this more practical. As the speed of these machines increase in the next few years, it will become feasible to employ prognostic, three-dimensional mesoscale/transport models to routinely predict atmospheric dispersion of pollutants, even to highly complex terrain. For example, the version of RAMS in this study could be run in a ``nowcasting`` model that would …
Date: December 31, 1994
Creator: Fast, J. D. & O`Steen, B. L.
System: The UNT Digital Library
Synthesis, tissue uptake, and toxicity of a nickel tetracarboranylphenylporphyrin (open access)

Synthesis, tissue uptake, and toxicity of a nickel tetracarboranylphenylporphyrin

Nickel tetracarbonylporphyrin (NiTCP) and VCDP, a boronated porphyrin, were chemically prepared and injected intraperitionally into mice. Toxicity as measured by hematologic and hepatic indices.
Date: December 31, 1994
Creator: Miura, M.; Micca, P. L.; Donaldson, J. A.; Heinrichs, J. C.; Slatkin, D. N.; Shelnutt, J. A. et al.
System: The UNT Digital Library
Felt-metal-wick heat-pipe solar receiver (open access)

Felt-metal-wick heat-pipe solar receiver

Reflux heat-pipe receivers have been identified as a desirable interface to couple a Stirling-cycle engine with a parabolic dish solar concentrator. The reflux receiver provides power nearly isothermally to the engine heater heads while decoupling the heater head design from the solar absorber surface design. The independent design of the receiver and engine heater head leads to higher system efficiency. Heat pipe reflux receivers have been demonstrated at approximately 65 kW{sub t} power throughput. Several 25 to 30-kW{sub e} Stirling-cycle engines are under development, and will soon be incorporated in commercial dish-Stirling systems. These engines will require reflux receivers with power throughput limits reaching 90-kW{sub t}. The extension of heat pipe technology from 60 kW{sub t} to 100 kW{sub t} is not trivial. Current heat pipe wick technology is pushed to its limits. It is necessary to develop and test advanced wick structure technologies to perform this task. Sandia has developed and begun testing a Bekaert Corporation felt metal wick structure fabricated by Porous Metal Products Inc. This wick is about 95% porous, and has liquid permeability a factor of 2 to 8 times higher than conventional technologies for a given maximum pore radius. The wick has been successfully demonstrated …
Date: December 31, 1994
Creator: Andraka, C. E.; Adkins, D. R.; Moss, T. A.; Cole, H. M. & Andreas, N. H.
System: The UNT Digital Library