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Issues for trigger processing at high luminosity colliders (open access)

Issues for trigger processing at high luminosity colliders

A number of issues for the design of trigger processors at future high-luminosity, high-energy colliders such as the Superconducting Super Collider and the Large Hadron Collider are discussed.
Date: November 1, 1989
Creator: Lankford, A.J.
System: The UNT Digital Library
Radio chemistry as a diagnostic in laser fusion experiments (open access)

Radio chemistry as a diagnostic in laser fusion experiments

Nuclear chemistry techniques have been employed in an attempt to measure the density of high compression laser fusion targets. Radioactive /sup 28/Al atoms formed in the /sup 28/Si(n,p)/sup 28/Al reaction arising from the interaction of the 14 MeV neutrons with the silicon atoms in the glass microsphere have been counted at Lawrence Livermore Laboratory using a ..beta..-..gamma.. coincidence method. The detection system that is employed allows activities corresponding to 100 aluminum atoms to be measured. From the observed number of activated atoms, neutron yields, and code calculations, information on the density of the compressed fuel can be obtained. This method is particularly valuable when the target compression becomes great enough to prohibit previously employed diagnostic techniques to be used. In addition, technique which utilizes a radioactive tracer to measure the isotropy of the target debris blowoff will also be discussed.
Date: November 1, 1977
Creator: Campbell, E.M.; Hicks, H.G.; Mead, W.C.; Glaros, S.S.; Coleman, L.W. & Laird, W.B.
System: The UNT Digital Library
Sodium compatibility of HT-9 and Fe-9Cr-1Mo steels (open access)

Sodium compatibility of HT-9 and Fe-9Cr-1Mo steels

Ferritic steels have been receiving significant attention for possible use as steam generator tubing, and as alternate structural materials for liquid-metal heat-transport systems in commercial fast reactors, fusion reactors, etc. The materials are chosen on the basis of their high thermal conductivity, resistance to stress-corrosion-cracking in aqueous and steam environments, favorable fabricability and fairly low cost. These steels are available in several classes based on the microstructure and alloy content, viz., martensitics, bainitics, delta ferritics, and duplex steels. The low alloy bainitic steels (Fe-2-1/4Cr-1Mo) undergo extensive decarburization when exposed to high temperature flowing sodium. It is for this reason that ferritic steels with higher chromium (9 to 12% Cr) content have been proposed to minimize the carbon transfer and eventual degradation of mechanical properties. The martensitic steels, HT-9 and improved Fe9Cr1Mo are being considered as cladding/duct materials for liquid metal reactors (LMR). The alloy HT-9 is based on 12Cr1Mo composition. The improved Fe9Cr1Mo alloy is based on 9Cr1Mo composition as its name implies. The objective of the work reported here is to evaluate the sodium compatibility of the alloys at temperatures and flow rates typical of LMR cores. Testing was done for 8104 hours at 60/sup 0/C and 3992 hours …
Date: November 1, 1985
Creator: Anantatmula, R. P. & Brehm, W. F.
System: The UNT Digital Library
VUV (vacuum ultraviolet) laser diagnostics of H sup - ion sources (open access)

VUV (vacuum ultraviolet) laser diagnostics of H sup - ion sources

Vacuum ultraviolet laser absorption spectroscopy has been employed to measure the populations and temperatures of ground electronic state H-atoms and vibrationally-excited H{sub 2} molecules in a volume H{sup -} ion source. Measurements of both species have been made under a variety of discharge conditions. Vibrational levels to v{double prime}=8 have been measured, with the vibrational population distribution well described by a temperature of 4150K. 10 refs., 9 figs.
Date: November 1, 1989
Creator: Young, A. T.; Stutzin, G. C.; Leung, K. N. & Kunkel, W. B.
System: The UNT Digital Library
Proceedings of a conference on solar energy for heating greenhouses and greenhouse-residential combinations (open access)

Proceedings of a conference on solar energy for heating greenhouses and greenhouse-residential combinations

Seventeen papers are included. A separate abstract was prepared for each for Energy Research Abstracts (ERA); eight are included in Energy Abstracts for Policy Analysis (EAPA). (MHR)
Date: November 1, 1977
Creator: Bond, T E; Godbey, L C & Zornig, H F
System: The UNT Digital Library
Anaerobic fermentation of simulated in-situ oil shale retort water (open access)

Anaerobic fermentation of simulated in-situ oil shale retort water

The feasibility of removing soluble organics from oil shale retort water by anaerobic digestion with methane production was experimentally investigated. The following conclusions were made. The retort water studied had to be pretreated to remove toxic and add deficient constituents before it could be successfully treated with the anaerobic fermentation process. Pretreatment included pH adjustment to 7, ammonia reduction, and nutrient addition. A digested sludge from a conventional municipal sewage treatment plant was successfully acclimated to the retort water studied. A major fraction of the organics in the retort water studied was stabilized by conversion to CH/sub 4/ and CO/sub 2/ using the anaerobic fermentation process. BOD/sub 5/ and COD removal efficiences were 76 to 80 percent. The effluent from anaerobic fermentation of the retort water studied (BOD/sub 5/ : 530 to 580 mg/l) may be suitable for treatment by conventional aerobic processes. The growth of the methane formers, which stabilize the organics, is nutrient limited in the retort water studied. The pretreatment of the retort water studied removed 49 percent of the BOD/sub 5/. This was probably due to the reduction in solubility of high molecular weight fatty acids at neutral pHs. A major component removed from the retort …
Date: November 1, 1977
Creator: Ossio, E. A.; Fox, J. P.; Thomas, J. F. & Poulson, R. E.
System: The UNT Digital Library
Theoretical modeling and experimental characterization of planar defects in Y sub 2 Ba sub 4 Cu sub 6+x O sub 14+x (open access)

Theoretical modeling and experimental characterization of planar defects in Y sub 2 Ba sub 4 Cu sub 6+x O sub 14+x

Crystallographic defects and phase transformations in the system Y{sub 2}Ba{sub 4}Cu{sub 6 + x}O{sub 14 + x}(0{le}{times}{le}4) are investigated by high resolution transmission electron microscopy (TEM) and static lattice, three dimensional Monte Carlo computer simulations. High resolution images of partially transformed (x = 2 to x = 1) material reveal a prevalence of CuO planar defects (stacking faults) associated with the transformation and an absence of disturbance to the perovskite Ba-Y-Ba blocks. An atomic mechanism involving the intercalculation and removal of extra CuO planes by partial dislocation climb, and requiring only a-b plane diffusion, is developed for the formation of such planar defects during changes in the layered YBaCuO crystal structure. Monte Carlo simulations based on the proposed transformation mechanism accurately reproduce the observed defects and known equilibrium structures. 24 refs., 4 figs.
Date: November 1, 1990
Creator: Burmester, C. P.; Fendorf, M.; Gronsky, R. & Wille, L. T.
System: The UNT Digital Library
Framework for control system development (open access)

Framework for control system development

Control systems being developed for the present generation of accelerators will need to adapt to changing machine and operating state conditions. Such systems must also be capable of evolving over the life of the accelerator operation. In this paper we present a framework for the development of adaptive control systems.
Date: November 1, 1991
Creator: Cork, C. & Nishimura, Hiroshi.
System: The UNT Digital Library
The geometry of the Virasoro group for physicists (open access)

The geometry of the Virasoro group for physicists

Diff(S/sup 1/), the group of reparametrizations of the circle, is known as the Virasoro group in string theory. Reparametrizations keeping fixed a point of the circle form the quotient space Diff(S/sup 1/)S/sup 1/. The geometry of this space is relevant for string theory and string field theory. We describe this space as an infinite dimensional complex manifold with a Kaehler metric and compute ist Riemann tensor and its Ricci tensor. 7 refs
Date: November 1, 1987
Creator: Zumino, B.
System: The UNT Digital Library
Strange-quark-matter stars (open access)

Strange-quark-matter stars

We investigate the implications of rapid rotation corresponding to the frequency of the new pulsar reported in the supernovae remnant SN1987A. It places very stringent conditions on the equation of state if the star is assumed to be bound by gravity alone. We find that the central energy density of the star must be greater than 13 times that of nuclear density to be stable against the most optimistic estimate of general relativistic instabilities. This is too high for the matter to consist of individual hadrons. We conclude that it is implausible that the newly discovered pulsar, if its half-millisecond signals are attributable to rotation, is a neutron star. We show that it can be a strange quark star, and that the entire family of strange stars can sustain high rotation if strange matter is stable at an energy density exceeding about 5.4 times that of nuclear matter. We discuss the conversion of a neutron star to strange star, the possible existence of a crust of heavy ions held in suspension by centrifugal and electric forces, the cooling and other features. 34 refs., 10 figs., 1 tab.
Date: November 1, 1989
Creator: Glendenning, N. K.
System: The UNT Digital Library
Ultrafast gated intensifier design for laser fusion x-ray framing applications (open access)

Ultrafast gated intensifier design for laser fusion x-ray framing applications

A major challenge for laser fusion is the study of the symmetry and the hydrodynamic stability of imploding fuel capsules. Streaked x-radiography, in one space and one time dimension, does not provide sufficient information. Two (spatial) dimensional frames of 10 to 100 ps duration are required with good image quality, minimum geometrical distortion (approximately 1%), dynamic range greater than 1000 and greater than 200 x 200 pixels. A gated transmission line imager (TLI) can meet these requirements with frame times between 30 and 100 ps. An instrument of this type is now being developed. Progress on this instrument including theory of operation, ultrafast pulse generation and propagation, component integration, and high resolution phosphor screen development are presented.
Date: November 1, 1983
Creator: Price, R.H.; Wiedwald, J.D.; Kalibjian, R.; Thomas, S.W. & Cook, W.M.
System: The UNT Digital Library
Proceedings of the US DOE/UK AEA Workshop on Facility Design (open access)

Proceedings of the US DOE/UK AEA Workshop on Facility Design

This document contains the proceeding of a Workshop on Facility Design that was held between the United States Department of Energy and the United Kingdom Atomic Energy Authority, Albuquerque, New Mexico, October 27--29, 1986. The intention of the workshop was to display relevant design criteria and to demonstrate for various US and UK facilities, current and projected criteria and how these criteria have been satisfied by facility design. Specific examples concern small plants, large plants, and waste stores.
Date: November 1, 1986
Creator: unknown
System: The UNT Digital Library
SANS (small angle neutron scattering) measurement of deuterium-dislocation correlation in palladium (open access)

SANS (small angle neutron scattering) measurement of deuterium-dislocation correlation in palladium

Small angle neutron scattering (SANS) measurements have been made on deformed polycrystal palladium samples with and without deuterium dissolved in the solution phase ({alpha}) at room temperature. Concentrations were held constant during SANS experiments by an equilibrium gas pressure cell. The difference scattering cross section for the same sample with and without deuterium loading has a 1/Q behavior (Q=4{pi}/{lambda} sin{theta}/2) at intermediate values of Q. At very low values of Q the dependence is much stronger than 1/Q. The 1/Q behavior is attributed to deuterium trapping close to long dislocation cores forming rod-like scattering structures.
Date: November 1, 1989
Creator: Heuser, B.J.; Summerfield, G.C.; King, J.S. (Michigan Univ., Ann Arbor, MI (USA)) & Epperson, J.E. (Argonne National Lab., IL (USA))
System: The UNT Digital Library
Lattice calculations of electroweak decay amplitudes (open access)

Lattice calculations of electroweak decay amplitudes

I review the progress made during the last year in lattice calculations of weak and electromagnetic amplitudes. 32 refs., 9 figs., 2 tabs.
Date: November 1, 1989
Creator: Sharpe, S.R.
System: The UNT Digital Library
Heavy ion reactions in the transition region (open access)

Heavy ion reactions in the transition region

Evidence is given for a serious and systematic failure of the DWBA to predict the cross sections for single nucleon transfers induced by heavy ions above about 10 MeV/Nucleon beam energies. This is perhaps related to a coherent coupling to an increasing cross section to the quasi-elastic continuum, which also shows an anomalous energy dependence at about the same energy.
Date: November 1, 1977
Creator: Hendrie, D. L.
System: The UNT Digital Library
Frontiers of particle beam physics (open access)

Frontiers of particle beam physics

First, a review is given of various highly-developed techniques for particle handling which are, nevertheless, being vigorously advanced at the present time. These include soft superconductor radio frequency cavities, hard superconductor magnets, cooling rings for ions and anti-protons, and damping rings for electrons. Second, attention is focused upon novel devices for particle generation, acceleration, and focusing. These include relativistic klystrons and free electron laser power sources, binary power multipliers, photocathodes, switched-power linacs, plasma beat-wave accelerators, plasma wake-field accelerators, plasma lenses, plasma adiabatic focusers and plasma compensators. 12 refs.
Date: November 1, 1989
Creator: Sessler, Andrew M.
System: The UNT Digital Library
Limits to Ductility Set by Plastic Flow Localization (open access)

Limits to Ductility Set by Plastic Flow Localization

The theory of strain localization is reviewed with reference both to local necking in sheet metal forming processes and to more general three dimensional shear band localizations that sometimes mark the onset of ductile rupture. Both bifurcation behavior and the growth of initial imperfections are considered. In addition to analyses based on classical Mises-like constitutive laws, approaches to localization based on constitutive models that may more accurately model processes of slip and progressive rupturing on the microscale in structural alloys are discussed. Among these non-classical constitutive features are the destabilizing roles of yield surface vertices and of non-normality effects, arising, for example, from slight pressure sensitivity of yield. Analyses based on a constitutive model of a progressively cavitating dilational plastic material which is intended to model the process of ductile void growth in metals are also discussed. A variety of numerical results are presented. In the context of the three dimensional theory of localization, it is shown that a simple vertex model predicts ratios of ductility in plane strain tension to ductility in axisymmetric tension qualitatively consistent with experiment, and the destabilizing influence of a hydrostatic stress dependent void nucleation criterion is illustrated. In the sheet necking context, and focussing …
Date: November 1, 1977
Creator: Needleman, A. & Rice, J. R.
System: The UNT Digital Library
Numerical computations of transport coefficients for nonsymmetric plasmas (open access)

Numerical computations of transport coefficients for nonsymmetric plasmas

The linearized drift kinetic equation is solved numerically to obtain the Onsager transport matrix for a three-dimensional toroidal plasma confinement geometry. Local transport coefficients relating the cross-field fluxes to the thermodynamic forces are computed as continuous functions of the collision frequency. In particular, in the low-collision-frequency regime (..nu.. < ..omega../sub b/), the transport resulting from the nonconservation of the longitudinal adiabatic invariant J (due to particle transitions from helically trapped to toroidally trapped) is obtained. The boundary layer in velocity space resulting from these transition particles can be accurately treated using a Legendre polynomial representation for the pitch angle dependence of the distribution function. Magnetic coordinates are used so that finite-beta effects are included. The disparity in the time scales between collisionless particle orbits and collisional dynamics is treated efficiently to obtain steady-state fluxes and viscosity coefficients. This yields significant improvements in the precision and computational effort in comparison with Monte Carlo methods. The effect of a radial electric field in the ..nu.. < ..omega../sub D/ regime is studied. Applications to Advanced Transition Facility (ATF) and heliac configurations are given.
Date: November 1, 1985
Creator: Hirshman, S. P.; Shaing, K. C.; Beasley, C. O. Jr.; Crume, E. C. & Van Rij, W. I.
System: The UNT Digital Library
Volume H/sup -/ ion production experiments at LBL (open access)

Volume H/sup -/ ion production experiments at LBL

H/sup -/ ions formed by volume processes have been extracted from a multicusp ion source. It is shown that a permanent magnet filter together with a small positive bias voltage on the plasma grid can produce a very significant reduction in electron drain as well as a sizable increase in H/sup -/ ions available for extraction. A further reduction in electron current is achieved by installing a pair of small magnets at the extraction aperture. An H/sup -/ ion current density of 38 mA/cm/sup 2/ was obtained with a discharge current of approximately 350 A. Different techniques to increase the H/sup -/ ion yield have also been investigated.
Date: November 1, 1983
Creator: Leung, K. N. & Ehlers, K. W.
System: The UNT Digital Library
Rotational population patterns and searches for the nuclear SQUID (Superconducting Quantum Interference Device) (open access)

Rotational population patterns and searches for the nuclear SQUID (Superconducting Quantum Interference Device)

This paper presents new theoretical results for rotational population patterns in the nuclear SQUID effect. (The term nuclear SQUID is in analogy to the solid-state Superconducting Quantum Interference Devices.) The SQUID effect is an interesting new twist to an old quest to understand Coriolis anti-pairing (CAP) effects in nuclear rotational bands. Two-neutron transfer reaction cross sections among high-spin states have long been touted as more specific CAP probes than other nuclear properties. Heavy projectiles like Sn or Pb generally are recommended to pump the deformed nucleus to as high spin as possible for transfer. The interference and sign reversal of 2n transfer amplitudes at high spin, as predicted in the early SQUID work imposes the difficult requirement of Coulomb pumping to near back-bending spins at closest approach. For Pb on rare earths we find a dramatic departure from sudden-approximation, so that the population depression occurs as low as final spin 10h. 14 refs., 8 figs.
Date: November 1, 1989
Creator: Canto, L.F.; Donangelo, R.J.; Farhan, A.R.; Guidry, M.W.; Rasmussen, J.O.; Ring, P. et al.
System: The UNT Digital Library
Noncanonical Hamiltonian methods in plasma dynamics (open access)

Noncanonical Hamiltonian methods in plasma dynamics

A Hamiltonian approach to plasma dynamics has numerous advantages over equivalent formulations which ignore the underlying Hamiltonian structure. In addition to achieving a deeper understanding of processes, Hamiltonian methods yield concise expressions (such as the Kubo form for linear susceptibility), greatly shorten the length of calculations, expose relationships (such as between the ponderomotive Hamiltonian and the linear susceptibility), determine invariants in terms of symmetry operations, and cover situations of great generality. In addition, they yield the Poincare invariants, in particular Liouville volume and adiabatic actions.
Date: November 1, 1981
Creator: Kaufman, A. N.
System: The UNT Digital Library
Superconducting magnets in high radiation environments: Design problems and solutions (open access)

Superconducting magnets in high radiation environments: Design problems and solutions

As part of the Stanford Linear Collider Project, three high-field superconducting solenoid magnets are used to rotate the spin direction of a polarized electron beam. The magnets are installed in a high-radiation environment, where they will receive a dose of approximately 10{sup 3} rad per hour, or 10{sup 8} rad over their lifetimes. This level of radiation and the location in which the magnets are installed, some 10 meters below ground in contiguous tunnels, required careful selection of materials for the construction of the solenoids and their ancillary cryogenic equipment, as well as the development of compatible component designs. This paper describes the materials used and the design of the equipment appropriate for the application. Included are summaries of the physical and mechanical properties of the materials and how they behave when irradiated. 16 refs., 7 figs., 1 tab.
Date: November 1, 1989
Creator: St. Lorant, S.J. & Tillmann, E.
System: The UNT Digital Library
Status of greater than or equal to 1 ampere H/sup -/ ion source development at the Lawrence Berkeley Laboratory (open access)

Status of greater than or equal to 1 ampere H/sup -/ ion source development at the Lawrence Berkeley Laboratory

This paper summarizes the effort to improve the operation of the approx. 1 A surface-production H/sup -/ ion source developed by K.W. Ehlers and K.N. Leung. The plasma chamber consists of a large magnetic bucket of oval cross section. A concave cylindrical converter surface is suspended in the plasma chamber to direct any surface-produced negative ions through the exit aperture. The ion source has been mated to a tetrode accelerator for the proof-of-principle tests. Most of the problems discovered in the tests were associated with difficulties in controlling the production process. This paper describes the plasma chamber in greater detail and illustrates the quality of the presnet ion production. The acceleration difficulties have been deferred until a better test-stand is completed.
Date: November 1, 1983
Creator: Lietzke, A. F.; Ehlers, K. W. & Leung, K. N.
System: The UNT Digital Library
Ion-induced surface modification of alloys (open access)

Ion-induced surface modification of alloys

In addition to the accumulation of the implanted species, a considerable number of processes can affect the composition of an alloy in the surface region during ion bombardment. Collisions of energetic ions with atoms of the alloy induce local rearrangement of atoms by displacements, replacement sequences and by spontaneous migration and recombination of defects within cascades. Point defects form clusters, voids, dislocation loops and networks. Preferential sputtering of elements changes the composition of the surface. At temperatures sufficient for thermal migration of point defects, radiation-enhanced diffusion promotes alloy component redistribution within and beyond the damage layer. Fluxes of interstitials and vacancies toward the surface and into the interior of the target induce fluxes of alloying elements leading to depth-dependent compositional changes. Moreover, Gibbsian surface segregation may affect the preferential loss of alloy components by sputtering when the kinetics of equilibration of the surface composition becomes competitive with the sputtering rate. Temperature, time, current density and ion energy can be used to influence the individual processes contributing to compositional changes and, thus, produce a rich variety of composition profiles near surfaces. 42 references.
Date: November 1, 1983
Creator: Wiedersich, H.
System: The UNT Digital Library