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Pion correlations as a function of atomic mass in heavy ion collisions

Description: The method of two pion interferometry was used to obtain source-size and lifetime parameters for the pions produced in heavy ion collisions. The systems used were 1.70 {center dot} A GeV {sup 56}Fe + Fe, 1.82 {center dot} A GeV {sup 40}Ar + KCl and 1.54 {center dot} A GeV {sup 93}Nb + Nb, allowing for a search for dependences on the atomic number. Two acceptances (centered, in the lab., at {approximately} 0{degrees} and 45{degrees}) were used for each system, allowing a search for dependences o… more
Date: November 26, 1989
Creator: Chacon, A.D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The production of sup 49 V, sup 93 Mo, sup 93m Nb and other long-lived isotopes in fusion materials with 14 MeV neutrons

Description: Results are presented for measurements of neutron cross sections for the production of {sup 49}V (331 d) from vanadium and for {sup 93}Mo (3500 a) and {sup 93m}Nb (16 a) from natural and {sup 94}Mo-enriched molybdenum targets near 14 MeV. The targets were irradiated at the Rotating Target Neutron Source II to fluences up to 10{sup 18} n/cm{sup 2}. Radiochemical separations were performed to separate the desired nuclides from interferring activities. Activity measurements were then performed usi… more
Date: January 1, 1989
Creator: Greenwood, L.R. & Bowers, D.L.
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Partner: UNT Libraries Government Documents Department
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Silicon-based coatings on niobium metal

Description: Silicon coatings on niobium substrates were subjected to thermal, ion beam and laser mixing, and the effectiveness of the different methods for the synthesis of graded interfaces was compared. The resulting metal/silicon interfaces were characterized by x-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES) and the Rutherford backscattering (RBS). 6 refs., 4 figs.
Date: January 1, 1989
Creator: Stupik, P. D.; Jervis, T. R.; Nastasi, M.; Donovan, M. M.; Barron, A. R. (Harvard Univ., Cambridge, MA (USA). Dept. of Chemistry; Los Alamos National Lab., NM (USA) et al.
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Partner: UNT Libraries Government Documents Department
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Niobium 1% zirconium/potassium and titanium/potassium life-test heat pipe design and testing

Description: Experimental lifetime performance studies currently in progress use Niobium-1% Zirconium (Nb-1Zr) and Titanium (Ti) heat pipes with potassium (K) as the working fluid. A heat pipe life-test matrix has been developed for testing the heat pipes. Because the corrosion rates in alkali metal heat pipes are affected by temperature and working fluid evaporation flux, the variable parameters of the experimental matrix are established as steady operating temperature and input heat flux density. Total im… more
Date: January 1, 1989
Creator: Sena, J.T. & Merrigan, M.A.
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Partner: UNT Libraries Government Documents Department
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Characterization of Rh films on Ta(110)

Description: The surface and electronic structure of Rh films on Ta(110) up to several monolayers thick on Ta(110) are characterized by photoemission, Auger emission, low energy electron diffraction and low energy ion scattering. From the variation of the Rh Auger peak-to-peak intensity as a function of evaporation time, Rh/Ta(110) appears to grow in the Stranski-Krastanov mode at room temperature. However, the LEIS data show that the Rh adatoms begin to cluster on Ta(110) before growth of the monolayer is … more
Date: January 1, 1989
Creator: Jiang, L. Q.; Ruckman, M. W. & Strongin, M.
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Partner: UNT Libraries Government Documents Department
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High-frequency cavity applications and measurements of high-temperature superconductors

Description: A potentially important application of high-temperature superconductors will be high-frequency accelerating cavities. Currently these materials are not competitive with Nb at liquid helium temperature or with Cu at room temperature. However, available data on high-quality single crystals suggest that the relatively poor rf properties (high surface resistance and low surface magnetic field) of bulk and film specimens are due to materials properties that can be eliminated by improved processing t… more
Date: January 1, 1989
Creator: Cooke, D.W. & Gray, E.R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Tensile behavior of tungsten/niobium composites at 1300--1600 K

Description: The tensile behavior of continuous-tungsten-fiber-reinforced niobium composites (W/Nb), fabricated by an arc-spray process, was studied in the 1300 to 1600 K temperature range. The tensile properties of the fiber and matrix components as well as the composites were measured and were compared to rule of mixtures (ROM) predictions. The deviation from the ROM was found to depend upon the chemistry of the tungsten alloy fibers, with positive deviations for ST300/Nb (i.e., stronger composite strengt… more
Date: January 1, 1989
Creator: Yun, Hee Mann (Cleveland State Univ., OH (USA)) & Titran, R.H. (National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center)
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Partner: UNT Libraries Government Documents Department
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Development of superconducting strand and cable with improved properties for use in SSC (Superconducting Super Collider) magnets

Description: The critical current requirement for the NbTi superconductor strand was set at 2750 A/mm/sup 2/ (5 T, 4.2 K) in the SSC Conceptual Design, compared with a value of 1800 A/mm/sup 2/ which was specified for the strand used in the Tevatron dipoles. In addition, a filament diameter of 5 ..mu..m, instead of the 9 ..mu..m diameter used in the Tevatron, was chosen to reduce field distortion at injection. In order to meet the requirements for field homogeneity, the dimensional requirements for both str… more
Date: February 1, 1989
Creator: Scanlan, R. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The characterization of Nb/sub 3/Sn superconductors for use in magnets of 19 T and greater

Description: Increased resolution of NMR spectrometry will require the use of very high field Nb/sub 3/Sn superconducting magnets. Here we report the results of our investigation into mechanical and temperature effects on internal-Sn superconductors similar to those proposed for use in a 900 MHz, 21 T NMR magnet system. Thermal precompression was found to be about 0.225%, and the irreversible strain was about 0.8%. Fatigue degradation was not observed at cyclic intrinsic strains below 0.575%. Additions of r… more
Date: August 8, 1989
Creator: Summers, L. T.; Strum, M. J. & Miller, J. R.
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Partner: UNT Libraries Government Documents Department
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High-field, high-current-density, stable superconducting magnets for fusion machines

Description: Designs for large fusion machines require high-performance superconducting magnets to reduce cost or increase machine performance. By employing force-flow cooling, cable-in-conduit conductor configuration, and NbTi superconductor, it is now possible to design superconducting magnets that operate a high fields (8-12 T) with high current densities (5-15 kA/cm/sup 2/ over the winding pack) in a stable manner. High current density leads to smaller, lighter, and thus less expensive coils. The force-… more
Date: January 1, 1989
Creator: Lue, J.W.; Dresner, L. & Lubell, M.S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Review of oxidation of Nb-1Zr

Description: A major objective of the SP-100 Program Nuclear Assembly Test is to demonstrate the performance of a full-scale nuclear subsystem of a 100-kWe space nuclear power supply. The test will be run in a large vacuum chamber to protect the Nb-1Zr components from oxidation during operation. Much information about the oxidation of niobium and Nb-1Zr alloy already exists, and previous work in this area is reviewed. Oxidation of Nb-1Zr can proceed by solution, internal oxidation, and/or film formation. At… more
Date: April 1, 1989
Creator: DiStefano, J.R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Cemented NbC-Co for geothermal drilling applications

Description: Sintering and hot isostatic pressing were explored to produce a range of NbC-Co materials. Stoichiometric NbC-10Co and NbC-20Co were sintered close to the theoretical density relatively easily. Cemented NbC{sub 0.83}-10Co and NbC{sub 0.83}-20Co were more difficult to process. Some dense materials were prepared by a combination of sintering and hot isostatic pressing at 1420{degrees} to 1450{degrees}C. The carbide in these samples appeared to have the composition NbC{sub 0.9}. Hardness, toughnes… more
Date: June 1, 1989
Creator: Rowcliffe, D.J. (SRI International, Menlo Park, CA (USA). Materials Research Lab.)
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Flux creep in multifilamentary conductors of NbTi and Nb sub 3 Sn

Description: Long term decay of the sextupole field has been observed in accelerator dipole magnets, and this effect has been linked to flux creep'' in the superconductor. To study this problem, the decay of the magnetization of multifilamentary conductors of NbTi and Nb{sub 3}Sn have been measured as a function of time. Measurements show that as a function of ln{ital t} this decay cannot always be characterized by a single decay rate. Long time decay rates are sometimes approximately half that which is obs… more
Date: January 1, 1989
Creator: Ghosh, A.K.; Xu, Youwen & Suenaga, M.
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Partner: UNT Libraries Government Documents Department
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Thermal conduction of SSC (Superconducting Super Collider) wire

Description: A method suitable for measuring the thermal conductivity of good thermal conductors at low temperatures was implemented. It successfully served its purpose: to detect the effect of doping with manganese the interfilament part of the copper matrix of the superconducting wire used in the magnets of the Superconducting Super Collider. It uses two heaters and one thermometer per sample reducing the accuracy requirement on the thermometers, automatically compensating for zero offsets and reducing th… more
Date: August 1, 1989
Creator: Kuchnir, M. & Tague, J.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Thermophysical properties of liquid niobium

Description: Thermophysical properties of most liquid metals are difficult to measure because of the very high temperatures and pressures required, but they are important for several reasons. These include understanding the fundamental physics of liquid metals and experimental modeling and design of exploding wires, foils and fuses. The melting points of all but a few metals are at high temperatures, with many exceeding 2000 K. The critical points of most metals exceed temperatures and pressures that may be… more
Date: January 1, 1989
Creator: Hixson, R.S. & Winkler, M.A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Microstructural studies of advanced austenitic steels

Description: This report presents the first complete microstructural and analytical electron microscopy study of Alloy AX5, one of a series of advanced austenitic steels developed by Maziasz and co-workers at Oak Ridge National Laboratory, for their potential application as reheater and superheater materials in power plants that will reach the end of their design lives in the 1990's. The advanced steels are modified with carbide forming elements such as titanium, niobium and vanadium. When combined wit… more
Date: November 15, 1989
Creator: Todd, J. A. & Ren, Jyh-Ching
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Fission in intermediate energy heavy ion reactions

Description: A systematic study of reaction mechanisms at intermediate energies (50--100 MeV/A) has been performed at the Lawrence Berkeley Laboratory's BeValac using medium weight projectiles on medium and heavy element targets. A gas and plastic phoswich detector system was employed which gave large geometric coverage and a wide dynamic response. The particles identified with the gas detectors could be characterized into three components - intermediate mass fragments (IMF), fission fragments (FF) and heav… more
Date: January 1, 1989
Creator: Wilhelmy, J.B.; Begemann-Blaich, M.; Blaich, T.; Boissevain, J.; Fowler, M.M.; Gavron, A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Fission in intermediate energy heavy ion reactions

Description: A systematic study of reaction mechanisms at intermediate energies (50--100 MeV/A) has been performed at the Lawrence Berkeley Laboratory's BeValac using medium weight projectiles on medium and heavy element targets. A gas and plastic phoswich detector system was employed which gave large geometric coverage and a wide dynamic response. The particles identified with the gas detectors could be characterized into three components--intermediate mass fragments (IMF), fission fragments (FF) and heavy… more
Date: April 1, 1989
Creator: Wilhelmy, J.B.; Begemann-Blaich, M.; Blaich, T.; Boissevain, J.; Fowler, M.M.; Gavron, A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Symposium on high temperature and materials chemistry

Description: This volume contains the written proceedings of the Symposium on High Temperature and Materials Chemistry held in Berkeley, California on October 24--25, 1989. The Symposium was sponsored by the Materials and Chemical Sciences Division of Lawrence Berkeley Laboratory and by the College of Chemistry of the University of California at Berkeley to discuss directions, trends, and accomplishments in the field of high temperature and materials chemistry. Its purpose was to provide a snapshot of high … more
Date: October 1, 1989
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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VAMAS interlaboratory comparisons of critical current vs. strain in Nb{sub 3}Sn

Description: A comparison is made of measurements of the effect of axial tensile strain on the critical current of multifilamentary Nb{sub 3}Sn superconductors by three different laboratories. Two of the laboratories used short sample testing apparatus wherein a straight section of conductor was cooled in a force-free state. One of the laboratories used a spring apparatus wherein a long sample was reacted in a coil shape and attached to a spring sample holder. The agreement between the results for the two l… more
Date: December 31, 1989
Creator: Ekin, J.W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Amorphous metal alloys produced by mechanical alloying

Description: Mechanical alloying is a powder metallurgy method used in commercial production of high temperature superalloys. Under specific conditions, mechanical alloying allows the synthesis of amorphous metal alloys from mixtures of pure metal powders or from the powders of intermetallic compounds. Because the amorphizing transformation during mechanical alloying is a solid state reaction, most of the difficulties related to the amorphization by rapid solidification of melts can be avoided. Mechanical a… more
Date: January 1, 1989
Creator: Tiainen, T. J. & Schwarz, R. B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Magnetic characteristics and measurements of filamentary Nb-Ti wire for the Superconducting Super Collider

Description: In synchrotron accelerator applications, such as the Superconducting Super Collider (SSC), superconducting magnets are cycled in magnetic field. Desirable properties of the magnets include field uniformity, field stability with time, small residual field, and fairly small energy losses upon cycling. This paper discusses potential sources of problems in achieving these goals, describes important magnetic characteristics to be considered, and reviews measurement techniques for magnetic evaluation… more
Date: December 31, 1989
Creator: Goldfarb, R. B. & Spomer, R. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Transverse stress effect on the critical current of internal tin and bronze process Nb{sub 3}Sn superconductors

Description: The effect of transverse stress on the critical current density, J{sub c}, has been shown to be significant in bronze process Nb{sub 3}Sn, with the onset of significant degradation at about 50 Mpa. In an applied field of 10 T, the magnitude of the effect is about seven times larger for transverse stress than for axial tensile stress. In a subsequent study, similar results were observed in another bronze process Nb{sub 3}Sn conductor made by a different manufacturer. The mechanism accounting for… more
Date: December 31, 1989
Creator: Ekin, J. W.; Bray, S. L.; Danielson, P.; Smathers, D.; Sabatini, R. L. & Suenaga, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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