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Prototype results of a high resolution vertex drift chamber for the Mark II SLC Upgrade detector (open access)

Prototype results of a high resolution vertex drift chamber for the Mark II SLC Upgrade detector

Test results from a full-length prototype of the drift chamber vertex detector for the Mark II SLC Upgrade detector are presented. The 22 cell jet chamber employs planes of grid wires above and below the sense wire plane to increase the electrostatic stability of the sense wires and to narrow the electron arrival time distribution. Two different grid designs have been investigated. The spatial resolution and pulse widths have been measured at a variety of operating points and for different timing schemes in a mixture of 92% CO/sub 2/ and 8% isobutane. Typical results at 3 atmospheres pressure give an average resolution over a 2 cm drift distance of 30 ..mu..m for both designs. Efficient double track detection is achieved for tracks separated by 500 ..mu..m for one design and by 1000 ..mu..m for the other.
Date: February 1, 1986
Creator: Alexander, J.; Hayes, K.; Hoard, C.; Hutchinson, D.; Jaros, J.; Odaka, S. et al.
System: The UNT Digital Library
Electron spectroscopy studies in heavy fermions (open access)

Electron spectroscopy studies in heavy fermions

Photoemission experiments (whereby an electron absorbs a packet of light energy and is able to escape from the host material due to its increased energy) can measure directly the energy distribution of electrons in various materials. Our measurements on a recently-discovered class of metallic materials called ''heavy fermions'' show that the electrons that actually carry the electric current in these metals exist only within an extremely narrow range of energies. This range, which we will call the bandwidth, is narrower than that found in ordinary metals like copper by at least a factor of 10. Indeed it is surprising that they can carry electric current at all since such narrow energy ranges (or band widths) are characteristic of electrons confined to their host atoms, as in a non-metal, rather than of electrons that are free to wander through a metal. 8 refs.
Date: February 1, 1986
Creator: Arko, A. J.
System: The UNT Digital Library
Neutron capture cross sections for /sup 86,87/Sr at Stellar temperatures (open access)

Neutron capture cross sections for /sup 86,87/Sr at Stellar temperatures

Cross sections have been measured from 100 eV to 1 MeV by the neutron-time-of-flight technique. The capture events were recorded by detecting the prompt gamma-ray cascade with two C/sub 6/D/sub 6/ scintillators, and were normalized to standard gold cross sections. The background was determined experimentally by utilizing the ''black resonance'' technique. A /sup 6/Li-glass scintillator was used to monitor the neutron flux. A Maxwellian-averaged capture cross section at kT = 30 keV of 74 +- 3 mb for /sup 86/Sr, and 102 +- 4 mb for /sup 87/Sr. (LEW)
Date: February 1, 1986
Creator: Bauer, R. W.; Mathews, G. J.; Becker, J. A. & Howe, R. E.
System: The UNT Digital Library
Deep inelastic lepton scattering from nucleons and nuclei (open access)

Deep inelastic lepton scattering from nucleons and nuclei

A pedagogical review is presented of results obtained from inclusive deep inelastic scattering of leptons from nucleons and nuclei, with particular emphasis on open questions to be explored in future experiments.
Date: February 1, 1986
Creator: Berger, E. L.
System: The UNT Digital Library
Hard Scattering And A Diffractive Trigger (open access)

Hard Scattering And A Diffractive Trigger

Conclusions concerning the properties of hard scattering in diffractively produced systems are summarized. One motivation for studying diffractive hard scattering is to investigate the interface between Regge theory and perturbative QCD. Another is to see whether diffractive triggering can result in an improvement in the signal-to-background ratio of measurements of production of very heavy quarks. 5 refs. (LEW)
Date: February 1, 1986
Creator: Berger, Edmond L.; Collins, John C.; Soper, Davison E. & Sterman, George
System: The UNT Digital Library
Collapse of Defect Cascades to Dislocation Loops in Cu3Au (open access)

Collapse of Defect Cascades to Dislocation Loops in Cu3Au

TEM and ordered Cu/sub 3/Au were employed to measure the probability of dislocation loop formation as functions of irradiating ion mass (Ar/sup +/, Cu/sup +/ and Kr/sup +/), energy (50 and 100 keV), and irradiation temperature (30 and 300/sup 0/K). Disordered zones were produced at every defect cascade site and imaged in dark-field superlattice reflections. Dislocation loops were imaged in fundamental reflections in the same sample areas to produce an accurate measurement of the probability of the collapse of each cascade to a dislocation loop, within a large set (approx.200) of defect cascades for each irradiation condition. The size distributions of dislocation loops and disordered zones were also measured. Defect cascades collapse to dislocation loops with significant probability (approx.0.5) even at 30/sup 0/K. Other observations include an increasing collapse probability with increasing cascade energy density (increasing ion mass) and with increasing sample irradiation temperature. However, no additional collapse was observed upon annealing from 30 to 300/sup 0/K, and no increase in collapse probability was observed upon increasing the bombarding ion energy from 50 to 100 keV. Disordered zone sizes also increased with increasing ion mass and with increasing sample irradiation temperature (30 to 300/sup 0/K).
Date: February 1, 1986
Creator: Black, T. J.; Jenkins, M. L.; English, C. A. & Kirk, M. A.
System: The UNT Digital Library
Long-term Changes in the Sensitivity of Quadrupole Mass Spectrometers (open access)

Long-term Changes in the Sensitivity of Quadrupole Mass Spectrometers

We routinely use quadrupole mass spectrometers (QMS) to monitor vacuum conditions, gas purity, and plasma-wall interactions in the Tokamak Fusion Test Reactor (TFTR) at Princeton. Two QMS systems have been operating on TFTR continuously for a two-year period. Both QMS systems are absolutely calibrated at weekly intervals using a six-part standard gas mixture. The calibration procedure is based on the use of transfer standards (ion gauge and capacitance manometer) that are calibrated against a primary standard (spinning rotor gauge) on an external vacuum system. We have identified variations in the efficiency of the QMS ionizer and drifts in the sensitivity of the electron multiplier ion detector to be the major reasons for the observed changes in overall OMS sensitivity. Weekly variations in sensitivity greater than 100% have been observed following system bakeout at 150/sup 0/C and with the use of rhenium filaments which were initially in the QMS ionizer. Operation of the QMS systems with tungsten filaments and at constant temperature has yielded more stable operation with weekly sensitivity changes generally being less than 10%. 7 refs., 7 figs.
Date: February 1, 1986
Creator: Blanchard, W.R.; McCarthy, P.J.; Dylla, H.F.; LaMarche, P.H. & Simpkins, J.E.
System: The UNT Digital Library
Tritium in the aquatic environment (open access)

Tritium in the aquatic environment

Tritium is of environmental importance because it is released from nuclear facilities in relatively large quantities and because it has a half life of 12.26 y. Most of the tritium released into the atmosphere eventually reaches the aqueous environment, where it is rapidly taken up by aquatic organisms. This paper reviews the current literature on tritium in the aquatic environment. Conclusions from the review, which covered studies of algae, aquatic macrophytes, invertebrates, fish, and the food chain, were that aquatic organisms incorporate tritium into their tissue-free water very rapidly and reach concentrations near those of the external medium. The rate at which tritium from tritiated water is incorporated into the organic matter of cells is slower than the rate of its incorporation into the tissue-free water. If organisms consume tritiated food, incorporation of tritium into the organic matter is faster, and a higher tritium concentration is reached than when the organisms are exposed to only tritiated water alone. Incorporation of tritium bound to molecules into the organic matter depends on the chemical form of the ''carrier'' molecule. No evidence was found that biomagnification of tritium occurs at higher trophic levels. Radiation doses from tritium releases to large populations of humans …
Date: February 1, 1986
Creator: Blaylock, B.G.; Hoffman, F.O. & Frank, M.L.
System: The UNT Digital Library
Effects of non-condensible gases on fluid recovery in fractured geothermal reservoirs (open access)

Effects of non-condensible gases on fluid recovery in fractured geothermal reservoirs

Numerical simulations are performed in order to investigate the effects of noncondensible gases (CO/sub 2/) on fluid recovery and matrix depletion in fractured geothermal reservoirs. The model used is that of a well producing at a constant bottomhole pressure from a two-phase fractured reservoir. The results obtained have received a complex fracture-matrix interaction due to the thermodynamics of H/sub 2/O-CO/sub 2/ mixtures. Although the matrix initially contributes fluids (liquid and gas) to the fractures, later on, the flow directions reverse and the fractures backflow fluids into the matrix. The amount of backflow depends primarily upon the flowing gas saturation in the fractures; the lower the flowing gas saturation in the fractures the more backflow. It is shown that the recoverable fluid reserves depend strongly on the amount of CO/sub 2/ present in the reservoir system.
Date: February 1, 1986
Creator: Bodvarsson, G.S. & Gaulke, S.
System: The UNT Digital Library
Proceedings of the nineteenth LAMPF Users Group meeting (open access)

Proceedings of the nineteenth LAMPF Users Group meeting

Separate abstracts were prepared for eight invited talks on various aspects of nuclear and particle physics as well as status reports on LAMPF and discussions of upgrade options. Also included in these proceedings are the minutes of the working groups for: energetic pion channel and spectrometer; high resolution spectrometer; high energy pion channel; neutron facilities; low-energy pion work; nucleon physics laboratory; stopped muon physics; solid state physics and material science; nuclear chemistry; and computing facilities. Recent LAMPF proposals are also briefly summarized. (LEW)
Date: February 1, 1986
Creator: Bradbury, J.N. (comp.)
System: The UNT Digital Library
Scintillation techniques and optical devices: summary report of the working group (open access)

Scintillation techniques and optical devices: summary report of the working group

Use of optical fiber techniques particularly in particle tracking is discussed. Fundamental aspects of scintillating tracking detectors using the fiber-optic waveguide are described, including candidate core materials, fiber manufacture, properties of the scintillation materials and waveguides, attenuation length, and radiation resistance. The general consensus is expressed that most of the basic building blocks needed for fiber detector readout exist but require optimization. Attention is given to the imaging system components, including image intensifiers, electronic cameras, and digitizing systems. Also of concern is the ability of scintillating fiber detectors to handle high rates due to their granularity. Requirements for triggering are given. Also discussed are tracking, photodiode devices, and calorimetry. (LEW)
Date: February 1, 1986
Creator: Bross, A. & Ruchti, R.
System: The UNT Digital Library
Thermomechanical modeling of the Spent Fuel Test-Climax (open access)

Thermomechanical modeling of the Spent Fuel Test-Climax

The Spent Fuel Test-Climax (SFT-C) was conducted to evaluate the feasibility of retrievable deep geologic storage of commercially generated spent nuclear-reactor fuel assemblies. One of the primary aspects of the test was to measure the thermomechanical response of the rock mass to the extensive heating of a large volume of rock. Instrumentation was emplaced to measure stress changes, relative motion of the rock mass, and tunnel closures during three years of heating from thermally decaying heat sources, followed by a six-month cooldown period. The calculations reported here were performed using the best available input parameters, thermal and mechanical properties, and power levels which were directly measured or inferred from measurements made during the test. This report documents the results of these calculations and compares the results with selected measurements made during heating and cooling of the SFT-C.
Date: February 1986
Creator: Butkovich, T. R. & Patrick, W. C.
System: The UNT Digital Library
Potential applications of NbN composites in fusion reactor magnets (open access)

Potential applications of NbN composites in fusion reactor magnets

Recent projected requirements for large scale fusion reactor magnets call for the development of advanced superconducting materials capable of producing peak magnetic fields in excess of 15 T with current densities in the windings in excess of 2 x 10/sup 3/ A/cm/sup 2/. These materials will be exposed to large stresses (up to 500 MPa) and neutron fluences as high as 10/sup 22/ n/cm/sup 2/ over the lifetime of the conductor. The demonstrated strain and radiation tolerance of NbN together with excellent superconducting properties make it a promising candidate to be used in a superconducting composite capable of satisfying these requirements. Our program at Argonne is directed towards demonstrating a method of fabrication which is capable of achieving these goals. Tests will be conducted on moderate lengths of NbN superconducting composites to verify the ability to achieve large overall current densities in magnetic fields up to 20 T. High field applications of NbN are also being investigated by groups in Japan and Germany.
Date: February 1, 1986
Creator: Capone, D. W., II; Gray, K. E.; Kampwirth, R. T. & Ho, H. L.
System: The UNT Digital Library
3-body final states in peripheral heavy-ion collisions: nuclear clustering structure and projectile excitation revisited (open access)

3-body final states in peripheral heavy-ion collisions: nuclear clustering structure and projectile excitation revisited

Even though peripheral heavy-ion collisions are less violent than their central counterparts, the large energy exchange between the reactants often leaves the primary products in excited particle-unstable states whose subsequent decay leads to 3 or more nuclei emerging in the final exit channel. These post-reaction, predominantly sequential de-excitation processes can sometimes provide interesting structural information about the parent nuclei. In fact, provided these processes are well understood, one can employ them as probes for studying initial properties of the fragments. This report discusses results of two experiments that deal with (1) nonstatistical, rare decay modes of the projectile, and (2) internal excitation energy of the projectile- and target-like fragments in peripheral collisions. The physics addressed in each is different, but the experimental and data-analysis techniques are so similar that it is relevant to join them together.
Date: February 1, 1986
Creator: Chan, Y.; Chavez, E.; Gazes, S.B.; Kamermans, R.; Schmidt, H.R.; Siwek-Wilczynska, J. et al.
System: The UNT Digital Library
Intermediate mass fragment emission from 8 to 40 MeV/u (open access)

Intermediate mass fragment emission from 8 to 40 MeV/u

Experimental data for fragmentation in the reactions /sup 93/Nb = /sup 9/Be, /sup 12/C, and /sup 27/Al are presented. Data were obtained from the LBL BEVALAC (25 to 40 MeV/u), GSI Unilac (11 to 18 MeV/u) and LBL SuperHILAC. These measurements imply, that over a large range of bombarding energies, intermediate mass fragments are produced by the bineary decay of a compound nucleus-like system. At low bombarding energies, these systems are associated with a complete fusion reaction, whereas for the larger energies the initial system is formed in an incomplete fusion reaction. The data shows a smooth evolution from the lower energies, where the statistical emission of intermediate mass fragments is well established, to the higher, intermediate energy regime. 4 refs., 2 figs.
Date: February 1, 1986
Creator: Charity, R. J.; McMahan, M. A.; Bowman, D. R.; Liu, Z. H.; McDonald, R. J.; Wozniak, G. J. et al.
System: The UNT Digital Library
Tilting mode in nuclear reactions (open access)

Tilting mode in nuclear reactions

The relation between tilting relaxation and the reaction plane dynamics is discussed, providing an intuitive understanding of the expression for the cross section close to the beam direction, which has recently been derived. Second, the tilting relaxation time and the related wriggling relaxation time are discussed, based upon nucleon exchange transport (window friction). Finally, recent experimental information on the tilting mode relaxation is discussed, and the dynamics of the tilting mode is discussed qualitatively for the three different types of nuclear reactions considered, compound nucleus fission, quasifission, and damped nuclear reactions. 9 refs., 3 figs.
Date: February 1, 1986
Creator: Dossing, T. & Randrup, J.
System: The UNT Digital Library
Constructing a coherent long-term global total ozone climatology from the BUV, MFR, and SBUV/TOMS data sets (open access)

Constructing a coherent long-term global total ozone climatology from the BUV, MFR, and SBUV/TOMS data sets

The backscatter ultraviolet spectrometer (BUV) aboard the NIMBUS 4 satellite provided global ozone data until mid-1977. The Total Ozone Mapping Spectrometer (TOMS) and Solar Backscattered Ultraviolet (SBUV) instrument aboard the NIMBUS 7 satellite began providing global ozone in November 1978. The only satellite derived global total ozone data available between the termination of the BUV data and the startup of the SBUV/TOMS data is that from the Multichannel Filter Radiometer (MFR) instrument aboard the Defense Meteorological Satellite Program (DMSP) series of satellites. The MFR and the SBUV/TOMS data are compared during the data overlap period in order to determine how well the MFR data might be used to represent the SBUV/TOMS and BUV data during the data gap period. 5 refs., 3 figs., 3 tabs.
Date: February 1, 1986
Creator: Ellis, J.S. & Luther, F.M.
System: The UNT Digital Library
Radiation-induced segregation and precipitation in molybdenum-rhenium alloys (open access)

Radiation-induced segregation and precipitation in molybdenum-rhenium alloys

Specimens of Mo-7 at. % Re and Mo-30 at. % Re were irradiated with 1.8 MeV /sup 4/He/sup +/ ions at elevated temperatures. Radiation-induced segregation of Re was measured during irradiation by in situ Rutherford backscattering spectrometry. Segregation of the undersized Re atoms in the same direction as the defect fluxes, i.e., toward the external surface, was observed. The amount of Re enrichment in the near-surface region was measured as a function of temperature and of dose at a calculated near-surface displacement rate near 1 x 10/sup -4/dpa/s. Segregation was observed at temperatures from 800 to 1500/sup 0/C in Mo-7Re, and from 850 to 1225/sup 0/C in Mo-30Re. Irradiated disks were examined by transmission electron microscopy. Precipitates of Chi phase were observed on grain boundaries, or in a thin layer at the irradiated surface in Mo-30Re after irradiation at temperatures from 750 to 1075/sup 0/C. Frequently, Chi precipitates formed with a crystallographic twin orientation with respect to the host matrix. No voids were observed for doses up to 1.6 dpa.
Date: February 1, 1986
Creator: Erck, R. A.; Wayman, C. M. & Rehn, L. E.
System: The UNT Digital Library
Proceedings of the workshop on requirements of mobile teleoperators for radiological emergency response and recovery (open access)

Proceedings of the workshop on requirements of mobile teleoperators for radiological emergency response and recovery

Individual papers have been processed separately for the data bases. (TEM)
Date: February 1, 1986
Creator: Foltman, A.J. (ed.)
System: The UNT Digital Library
Plasma measurements with the TMX-U E parallel to B end-loss-ion spectrometers (open access)

Plasma measurements with the TMX-U E parallel to B end-loss-ion spectrometers

Two E parallel to B end-loss-ion spectrometers (ELIS) are now making plasma measurements on Tandem Mirror Experiment-Upgrade (TMX-U). One instrument is mounted on each end of this open-ended tandem-mirror machine. These spectrometers observe plasma losses along magnetic-field lines. They operate reliably and with a minimum of attention during an experimental run. Their data, which are quickly acquired and analyzed, help guide the experimental sequence. The parallel electric and magnetic fields separate the end-loss ions according to mass (D/sup +/ and H/sup +/) and energy. Each spectrometer detects ions with an array of 128 flat collector plates that are made from copper-coated G10 epoxy fiberglass, normally used for printed-circuit boards. The ELIS diagnostic system produces a wealth of experimental information, including data on peak plasma potential, central-cell ion temperature, potentials in the thermal-barrier region, axial confinement and ion-end-loss plugging, energetic-electron losses, and hydrogen/deuterium concentrations. 6 refs., 5 figs.
Date: February 18, 1986
Creator: Foote, J. H.; Wood, B. E.; Brown, M. D. & Curnow, G. M.
System: The UNT Digital Library
Proposal for a new tomographic device providing information on the chemical properties of a body section (open access)

Proposal for a new tomographic device providing information on the chemical properties of a body section

A system to analyze the chemical properties of a region of tissue located deep inside the human body without having to access it is proposed. The method is based on a high precision detection of x-rays or ..gamma..-rays (photons) from an external source Compton scattered from the tissue under inspection. The method provides chemical information of plane regions lying not too deep inside the body (<6 cm). The amount of radiation absorbed by the body is about the same as needed for a standard x-ray tomography. The exposure time is estimated to be shorter than 10 minutes. 37 refs., 13 figs.
Date: February 27, 1986
Creator: Gatti, E.; Rehak, P. & Kemmer, J.
System: The UNT Digital Library
Evaluation and design of a large spacing loop-loop electromagnetic tool (open access)

Evaluation and design of a large spacing loop-loop electromagnetic tool

This paper investigates the potential use of a large spacing loop-loop electromagnetic logging tool to detect resistivity anomalies as far as 25 meters away from the borehole wall. A three-dimensional whole space electromagnetic modelling code was used to evaluate the response of such a tool to various transmitter and receiver loop orientations, operating frequencies, loop spacings, resistivity contrasts, anomaly sizes and anomaly distances. Anomalies were modeled as finite extent sheets of various thicknesses which terminated before intersecting the borehole wall. It was found that both coplanar and coaxial loop orientations provide strong anomaly response, but the coaxial loop orientation has superior depth penetration and is a less complex tool to design and build. For such a coaxial tool, anomalies could be detected as far from the borehole wall as half the loop spacing. For rock resistivities on the order of 100 ohm-m, contrasts greater than 2:1 and loop spacings of 75 meters the optimal operating frequency is shown to be 10 kHz. At these loop spacings, anomalies must be thicker 10 meters to be detected. It is further shown that for coaxial loops the nature of the response curves allows one to estimate the distance of an anomaly from the …
Date: February 1, 1986
Creator: Harben, P.E.; Rodgers, P.W. & Holladay, G.
System: The UNT Digital Library
Simple, compact, high brightness source for x-ray lithography and x-ray radiography (open access)

Simple, compact, high brightness source for x-ray lithography and x-ray radiography

A simple, compact, high brightness x-ray source has recently been built. This source utilizes a commercially available, cylindrical geometry electron beam evaporator, which has been modified to enhance the thermal cooling to the anode. Cooling is accomplished by using standard, low-conductivity laboratory water, with an inlet pressure of less than 50 psi, and a flow rate of approx.0.3 gal/min. The anode is an inverted cone geometry for efficient cooling. The x-ray source has a measured sub-millimeter spot size (FWHM). The anode has been operated at 1 KW e-beam power (10 KV, 100 ma). Higher operating levels will be investigated. A variety of different x-ray lines can be obtained by the simple interchange of anodes of different materials. Typical anodes are made from easily machined metals, or materials which are vacuum deposited onto a copper anode. Typically, a few microns of material is sufficient to stop 10 KV electrons without significantly decreasing the thermal conductivity through the anode. The small size and high brightness of this source make it useful for step and repeat exposures over several square centimeter areas, especially in a research laboratory environment. For an aluminum anode, the estimated Al-K x-ray flux at 10 cms from the source …
Date: February 19, 1986
Creator: Hawryluk, A.M.
System: The UNT Digital Library
Optical systems for synchrotron radiation. Lecture 1. Introductory topics. Revision (open access)

Optical systems for synchrotron radiation. Lecture 1. Introductory topics. Revision

Various fundamental topics are considered which underlie the design and use of optical systems for synchrotron radiation. The point of view of linear system theory is chosen which acts as a unifying concept throughout the series. In this context the important optical quantities usually appear as either impulse response functions (Green's functions) or frequency transfer functions (Fourier Transforms of the Green's functions). Topics include the damped harmonic oscillator, free-space optical field propagation, optical properties of materials, dispersion, and the Kramers-Kronig relations.
Date: February 1, 1986
Creator: Howells, M.R.
System: The UNT Digital Library