Spin structures of Fe/Gd and Fe/Cr multilayers determined by polarized neutron reflectometry (open access)

Spin structures of Fe/Gd and Fe/Cr multilayers determined by polarized neutron reflectometry

Polarized neutron reflection was used to determine the magnetic structure of two different antiferromagnetically coupled multilayer systems, Fe/Gd and Fe/Cr. In Fe/Gd, the Fe and Gd moments are coupled antiparallel at the interface. At low temperatures a surface induced magnetic phase transition was found. In Fe/Cr, annealing at temperatures of up to 425{degrees}C, resulted in the degrading of antiferromagnetic coupling between Fe layers and in the formation of ferromagnetically coupled regions.
Date: August 1, 1992
Creator: Loewenhaupt, M.; Hahn, W. (Forschungszentrum Juelich GmbH (Germany). Inst. fuer Festkoerperforschung); Huang, Y. Y.; Felcher, G. P. (Argonne National Lab., IL (United States)) & Parkin, S. S. P. (IBM Research Div., San Jose, CA (United States). Almaden Research Center)
System: The UNT Digital Library
Resolution of safety issues associated with the storage of high-level radioactive waste at the Hanford Site (open access)

Resolution of safety issues associated with the storage of high-level radioactive waste at the Hanford Site

A number of high-level radioactive waste (HLW) safety issues have been identified at the Hanford Site in southeastern Washington State. Resolution of these issues is one of the Highest Priorities of the US Department of Energy. The most urgent issues are the potential for explosions in certain tanks (due to periodic venting of large quantities of flammable gases, or the presence of substantial quantities of ferrocyanide and/or organic compounds in combination with nitrates-nitrites). Other safety issues have been identified as well, such as the requirement for periodic water additions to one tank to control its temperature and the release of noxious vapors from a number of tanks. Substantial progress has been made toward safety issue resolution. Potential mechanisms have been identified for the generation, retention and periodic venting of flammable gas mixtures; potential methods for controlling the periodic release behavior have been identified and in-tank testing will be initiated in 1992. Research is being conducted to determine the initiation temperatures, energetics, reaction sequences and effects of catalysts and initiators on ferrocyanide-nitrate/nitrite reactions; waste characterization on a tank-by-tank basis will be required to identify whether ferrocyanide-containing wastes are safe to store as-is or will require further treatment to eliminate safety concerns. …
Date: August 1, 1992
Creator: Mellinger, G. B. (Pacific Northwest Lab., Richland, WA (United States)) & Tseng, J. C. (USDOE Assistant Secretary for Environmental Restoration and Waste Management, Washington, DC (United States))
System: The UNT Digital Library
Frontiers of accelerator instrumentation (open access)

Frontiers of accelerator instrumentation

New technology has permitted significant performance improvements of established instrumentation techniques including beam position and profile monitoring. Fundamentally new profile monitor strategies are required for the next generation of accelerators, especially linear colliders (LC). Beams in these machines may be three orders of magnitude smaller than typical beams in present colliders. In this paper we review both the present performance levels achieved by conventional systems and present some new ideas for future colliders.
Date: August 1, 1992
Creator: Ross, M.
System: The UNT Digital Library
Well, hydrology, and geochemistry problems encountered in ATES systems and their solutions (open access)

Well, hydrology, and geochemistry problems encountered in ATES systems and their solutions

In aquifer thermal energy storage (ATES) systems, wells provide the interface between the energy storage and use. Efficient operational wells are, therefore, essential for the system to run at maximum (design) efficiency. Adequate test drilling to accurately predict aquifer properties is essential in the design phase; proper construction and development are crucial; and proper monitoring of performance is necessary to identify the early stages of clogging and to evaluate the adequacy of well rehabilitation. Problems related to hydrology, well, and aquifer properties include: loss of permeability resulting from gas exsolution, chemical precipitation, and dispersion and movement of fine-grained particles; loss of recoverable heat caused by excessive regional ground-water gradient, hydrodynamic mixing of injected and native ground water, buoyancy flow and heat conduction through the cap and base of the storage zone; leakage up along the well casing; and fracturing'' of a shallow upper aquiclude as a result of an injection pressure greater than the hydrostatic pressure on the aquiclude. The predominant geochemical problems encountered are precipitation of carbonates in some areas and iron plus manganese oxides in others. These precipitation problems can be anticipated, and thus avoided, via geochemical calculations. The likelihood of iron carbonate precipitation is less certain because …
Date: August 1, 1992
Creator: Jenne, E. A. (Pacific Northwest Lab., Richland, WA (United States)); Andersson, O. (VBB VIAK AB, Malmo (Sweden)) & Willemsen, A. (IF Technology, Arnhem, (Netherlands))
System: The UNT Digital Library
Designing reliability into accelerators (open access)

Designing reliability into accelerators

For the next generation of high performance, high average luminosity colliders, the factories,'' reliability engineering must be introduced right at the inception of the project and maintained as a central theme throughout the project. There are several aspects which will be addressed separately: Concept; design; motivation; management techniques; and fault diagnosis.
Date: August 1, 1992
Creator: Hutton, A.
System: The UNT Digital Library
Design of the Nb[sub 3]Sn dipole D20 (open access)

Design of the Nb[sub 3]Sn dipole D20

The design of a 50 mm bore superconducting Nb[sub 3]Sn dipole with a short sample field of 13 T at 4.3 K and a current of 5500 A/turn is presented. The magnet is composed by two double pancake layers. The inner cable has 37 strands with a strand diameter of 0.75 mm and a Cu/Sc ratio of 0.4; the outer cable has 47 strands with a diameter of 0.48 mm and a Cu/Sc ratio of 1.15. In order to obtain a high transfer function and low saturation effects on the multipoles, the stainless steel collar is elliptical and the iron yoke is close-in.'' The thin collar itself provides only a minimum prestress and the full prestress of 100 MPa is given by a 25 mm welded stainless steel shell or by winding a wire around the yoke. Aluminum spacers are used as assembly tools and as a means to control the gap size in the vertically split iron yoke. This paper presents the magnetic design and the calculated stress and strain distribution in structure and coils. A 1 m model called D20 is to be built and tested at LBL.
Date: August 1, 1992
Creator: Dell'Orco, D.; Scanlan, R. & Taylor, C. E.
System: The UNT Digital Library
Intense beams at the micron level for the Next Linear Collider (open access)

Intense beams at the micron level for the Next Linear Collider

High brightness beams with sub-micron dimensions are needed to produce a high luminosity for electron-positron collisions in the Next Linear Collider (NLC). To generate these small beam sizes, a large number of issues dealing with intense beams have to be resolved. Over the past few years many have been successfully addressed but most need experimental verification. Some of these issues are beam dynamics, emittance control, instrumentation, collimation, and beam-beam interactions. Recently, the Stanford Linear Collider (SLC) has proven the viability of linear collider technology and is an excellent test facility for future linear collider studies.
Date: August 1, 1991
Creator: Seeman, J. T.
System: The UNT Digital Library
Design of high-T[sub c] superconducting bolometers for a far infrared imaging array (open access)

Design of high-T[sub c] superconducting bolometers for a far infrared imaging array

The design of high-[Tc] superconducting bolometers for use in a far infrared imaging array from wavelengths 30--100[mu]m is discussed. Measurements of the voltage noise in thin films of YBa[sub 2]CU[sub 3]O[sub 7-[var sigma]] on yttria-stabilized zirconia buffer layers on silicon substrates are used to make performance estimates. Useful opportunities exist for imaging and spectroscopy with bolometer arrays made on micro-machined silicon membranes. A circuit on each pixel which performs some signal integration can improve the sensitivity of large two-dimensional arrays of bolometers which use multiplexed readout amplifiers.
Date: August 1, 1992
Creator: Verghese, S.; Richards, P. L.; Fork, D. K.; Char, K. & Geballe, T. H.
System: The UNT Digital Library
A probabilistic approach to information retrieval in heterogeneous databases (open access)

A probabilistic approach to information retrieval in heterogeneous databases

During the post decade, organizations have increased their scope and operations beyond their traditional geographic boundaries. At the same time, they have adopted heterogeneous and incompatible information systems independent of each other without a careful consideration that one day they may need to be integrated. As a result of this diversity, many important business applications today require access to data stored in multiple autonomous databases. This paper examines a problem of inter-database information retrieval in a heterogeneous environment, where conventional techniques are no longer efficient. To solve the problem, broader definitions for join, union, intersection and selection operators are proposed. Also, a probabilistic method to specify the selectivity of these operators is discussed. An algorithm to compute these probabilities is provided in pseudocode.
Date: August 1, 1991
Creator: Chatterjee, A. & Segev, A.
System: The UNT Digital Library
Detection of organic sulfur by [sup 15]N and [sup 19]F NMR via formation of iminosulfuranes (open access)

Detection of organic sulfur by [sup 15]N and [sup 19]F NMR via formation of iminosulfuranes

We have synthesized new iminosulfuranes from a variety of diaryl-and dialkyl sulfides and dibenzothiophene. The pattern of [sup 15]N chemical shifts indicates that functional groups attached to sulfur are not simply resolved into aryl and alkyl groups. Thus, resolution of sulfur functional groups using [sup 15]N NMR via iminosulfurane does not appear practicable. However, iminosulfurane formation, together with the N-haloamide reaction and the Pummerer rearrangement, provides pathways for chemical discrimination of different sulfur substituents using unique [sup 15]N- or, [sup 19]F-labelled fragments for different categories of sulfur functional groups. In efforts currently underway, we are applying these reactions to methylated extracts and conversion products of the high-organic-sulfur containing Yugoslavian Rasa and Spanish Mequinenza lignites. 1 tab, 14 refs.
Date: August 1, 1992
Creator: Franz, J. A.; Linehan, J. C. & Lamb, C. N.
System: The UNT Digital Library
Precise predictions for neutrino masses and mixings (open access)

Precise predictions for neutrino masses and mixings

This report discusses the motivation and the results of predictions of neutrino masses and coupling constants.
Date: August 1, 1992
Creator: Hall, L. J.
System: The UNT Digital Library
Mechanical performance of full-scale prototype quadrupole magnets for the SSC (open access)

Mechanical performance of full-scale prototype quadrupole magnets for the SSC

Six 5-m-long prototype quadrupole magnets have been built and cold-tested at Lawrence Berkeley Laboratory for the Superconducting Super Collider. Each of the magnets contained instrumentation to monitor the mechanical performance of the magnets during assembly and cold-testing. In addition, the instrumentation was used along with physical measurements as aids during magnet assembly. Quantities measured include coil pressures during assembly, cooldown, and magnet energization; axial thermal contraction of the magnets during cooldown; and axial force transmitted to the magnet end-plates. For the most part, mechanical measurements have proven repeatable and agree well with analysis.
Date: August 1, 1992
Creator: Cortella, J. M.; Wandesforde, A. (Lawrence Berkeley Lab., CA (United States)) & Devred, A. (Superconducting Super Collider Lab., Dallas, TX (United States))
System: The UNT Digital Library
High power rf window and waveguide component development and testing above 100 MW at X-band (open access)

High power rf window and waveguide component development and testing above 100 MW at X-band

SLAC is committed to developing an X-band source capable of producing 100 Megawatt, 1 microsecond pulses to power the next linear collider. The first experience encountered at SLAC in the X-Band Regime above a few Megawatts was in the relativistic klystron program in cooperation with LLNL and LBL. About 280 MW had been transmitted through a variety of waveguide components but at very short pulse widths ({approximately}40 nanseconds) and very low pulse repetition rates. The likelihood of high peak power rf breakdown in most X-band components and especially rf windows increases as the rf pulse length becomes longer. Testing components at peak power levels above that at which they are expected to reliably perform is essential in a development program.
Date: August 1, 1992
Creator: Fowkes, W. R.; Callin, R. S. & Vlieks, A. E. (Stanford Linear Accelerator Center, Menlo Park, CA (United States))
System: The UNT Digital Library
Effect of substrate-twin-induced microstructure on transport properties of epitaxial Tl sub 2 Ba sub 2 CaCu sub 2 O sub x films in a magnetic field (open access)

Effect of substrate-twin-induced microstructure on transport properties of epitaxial Tl sub 2 Ba sub 2 CaCu sub 2 O sub x films in a magnetic field

The role of substrate-induced microstructure on transport properties in c-axis oriented epitaxial Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub x} films grown on LaAlO{sub 3} and SrTiO{sub 3} has been studied. For a magnetic field parallel to the Cu-0 planes, resistivity and the critical current density, J{sub c}, have been measured as a function of angle {theta} between the applied field and the direction of transport current. Resistivity dips and enhancement of the critical current density, J{sub c}, were observed for magnetic fields applied parallel to the substrate twins in LaAlO{sub 3} in high fields ({ge} 2 T). Meanwhile for films on SrTiO{sub 3}, resistivity and J{sub c} were Lorentz-force independent.
Date: August 1, 1992
Creator: Kim, D. H.; Miller, D. J.; Hettinger, J. D.; Gray, K. E.; Landis, P. G.; Sharping, J. E. (Argonne National Lab., IL (United States)) et al.
System: The UNT Digital Library
Experimental study of the Main Ring transition crossing (open access)

Experimental study of the Main Ring transition crossing

A 12 sec long Main Ring cycle was used with an unbunched beam of low intensity to measure the change of the revolution frequency of the beam as a function of the central momentum setting determined by the magnetic field. The transition gamma was determined as the first order term in the change in the revolution frequency versus fractional change in the momentum, but the nonlinear term {alpha}{sub 1} could not be determined because of the limited momentum aperture of the Main Ring and the present measurement resolution.
Date: August 1, 1992
Creator: Kourbanis, I. & Ng, King-Yuen.
System: The UNT Digital Library
Interpretation of rapidly rotating pulsars (open access)

Interpretation of rapidly rotating pulsars

The minimum possible rotational period of pulsars, which are interpreted as rotating neutron stars, is determined by applying a representative collection of realistic nuclear equations of state. It is found that none of the selected equations of state allows for neutron star rotation at periods below 0.8--0.9 ms. Thus, this work strongly supports the suggestion that if pulsars with shorter rotational periods were found, these are likely to be strange-quark-matter stars. The conclusion that the confined hadronic phase of nucleons and nuclei is only metastable would then be almost inescapable, and the plausible ground-state in that event is the deconfined phase of (3-flavor) strange-quark-matter.
Date: August 5, 1992
Creator: Weber, F. (Technische Univ. Muenchen, Garching (Germany). Inst. fuer Theoretische Physik) & Glendenning, N. K. (Lawrence Berkeley Lab., CA (United States))
System: The UNT Digital Library
High-Energy Corona for destruction of volatile organic contaminants in process off-gases (open access)

High-Energy Corona for destruction of volatile organic contaminants in process off-gases

A small (2 scfm) High-Energy Corona (HEC) reactor was developed to produce a non-equilibrium plasma in a concentric-cylinder geometry. A volume-filling plasma was produced in a packed bed, and initial tests have demonstrated the ability to destroy up to 1500 ppM trichloroethylene at a flow rate of 1.4 scfm, with greater than 99% destruction observed. Destruction efficiency is examined as a function of inlet TCE concentration, bed height (residence time) and applied voltage. Hydrochloric acid appears to be the primary chlorinated byproduct, and can be removed by conventional wet or dry scrubbing.
Date: August 1, 1992
Creator: Virden, J. W.; Heath, W. O.; Goheen, S. C.; Miller, M. C.; Mong, G. M. & Richardson, R. L.
System: The UNT Digital Library
A finite different field solver for dipole modes (open access)

A finite different field solver for dipole modes

A finite element field solver for dipole modes in axisymmetric structures has been written. The second-order elements used in this formulation yield accurate mode frequencies with no spurious modes. Quasi-periodic boundaries are included to allow travelling waves in periodic structures. The solver is useful in applications requiring precise frequency calculations such as detuned accelerator structures for linear colliders. Comparisons are made with measurements and with the popular but less accurate field solver URMEL.
Date: August 1, 1992
Creator: Nelson, E. M.
System: The UNT Digital Library
NMR on beta-emitting fragment [sup 43]Ti (open access)

NMR on beta-emitting fragment [sup 43]Ti

NMR has been observed on beta-emitting [sup 43]Ti produced in the 116 AMeV [sup 46]Ti on C collision by means of asymmetric beta decay. The observed spin polarization of [sup 43]Ti showed a reverse tendency in its momentum dependence compared with that observed for fragments produced in the [sup 40]Ca on Au collision. This suggests negative angle deflection of [sup 43]Ti due to the nuclear attractive potential. From the observed NMR spectrum, the magnetic moment of [sup 43]Ti was determined to be [vert bar][mu][vert bar] =(0.85 [plus minus] 0.02)[mu][sub N]. The value is significantly quenched from the single particle value [minus]1.91 [mu][sub N], which shows a strong effect due to meson exchange currents and configuration mixing.
Date: August 1, 1992
Creator: Matsuta, K.; Ozawa, A.; Nojiri, Y.; Minamisono, T.; Fukuda, M.; Momota, S. et al.
System: The UNT Digital Library
Environmental Restoration Program Control Management System (open access)

Environmental Restoration Program Control Management System

Environmental Restoration managers need to demonstrate that their programs are under control. Unlike most industrial programs, the public is heavily involved in Environmental Restoration activities. The public is demanding that the country prove that real progress is being made towards cleaning up the environment. A Program Control Management System can fill this need. It provides a structure for planning, work authorization, data accumulation, data analysis and change control. But it takes time to implement a control system and the public is losing its patience. This paper describes critical items essential to the quick development and implementation of a successful control system.
Date: August 13, 1992
Creator: Duke, R. T.
System: The UNT Digital Library
On Monitoring Nuclear Power Plant Emergency Diesel Generator Reliability (open access)

On Monitoring Nuclear Power Plant Emergency Diesel Generator Reliability

If offsite power is interrupted, the availability of onsite alternating current power supplies is a major factor in assuring acceptable safety at commercial light-water-cooled nuclear power plants. To control the risk of severe care damage during station blackout accidents at a given plant, the reliability of the emergency diesel generators (EDGS) to start and load-run upon demand must be maintained at a sufficiently high level. The minimum EDG reliability, which we denote by RT, is targeted at either 0.95 or 0.975 per nuclear unit consistent with the reliability level that the plant operator assumed in the coping analysis for station blackout. In 1992 the US Nuclear Regulatory Commission (NRC) considered an amendment that would require licensees to test and monitor EDG reliability against performance-based criteria that indicate possible degradation from the EDG target reliability levels. They originally proposed the following set of fixed sample-size triggers for use in monitoring EDG reliability. The purpose of this report is to compare the performance of the proposed triggers with corresponding alternative sequential variable sample-size triggers which potentially permit earlier detection of EDG reliability degradation without significantly increasing the false alarm rate. The comparison is to be done in a simulated use environment by …
Date: August 11, 1993
Creator: Martz, H. F.; Tietjen, G. L.; Kvam, P. H. (Los Alamos National Lab., NM (United States)) & Abramson, L. R. (Nuclear Regulatory Commission, Washington, DC (United States))
System: The UNT Digital Library
The accuracy of beam-beam diagnostics for circular colliders (open access)

The accuracy of beam-beam diagnostics for circular colliders

We investigate the potential of beam-beam deflection techniques for the determination of spot sizes, tilt angle, centering, and angular divergence for circular colliders. Achievable accuracies for all measured quantities are estimated.
Date: August 1, 1992
Creator: Ziemann, V.
System: The UNT Digital Library
A 50 mm bore superconducting dipole with a unique iron yoke structure (open access)

A 50 mm bore superconducting dipole with a unique iron yoke structure

A 50 mm bore superconducting dipole with a thin stainless steel collar and a close in elliptical iron yoke was designed in order to obtain a high transfer function SW low saturation effects on the multipoles, and a one meter model was built and tested. Training behavior of the first 1 m model, called D19, is presented at 4.3 K and 1.8 K. At 1.8 K it reached the record field of 10.06 T. The two layer cos [theta] winding uses 30 and 36 strand cables identical to the cables of the 50 mm bore SSC dipole and it has an operating field of 6.6 T at 4.35 K with a current of 5800 A. To evaluate behavior at high fields, the mechanical structure for the model was designed for 10 T. The thin collar itself provides only a minimum prestress of 10 MPa. and the full prestress of 70 MPa is given by the iron yoke. An aluminum spacer is used to control the gap size in the vertically split iron yoke. The tapered gap in the yoke is determined by the size of the Al spacer so that during cooldown there is no loss of coil prestress and …
Date: August 1, 1992
Creator: Dell'Orco, D.; Caspi, S.; O'Neill, J.; Lietzke, A.; Scanlan, R.; Taylor, C. E. et al.
System: The UNT Digital Library
SLAC A-Line upgrade to 50 GeV (open access)

SLAC A-Line upgrade to 50 GeV

The SLAC A-Line, originally developed to transport electron beams to experiments in End Station A at energies up to 25 GeV, is being upgraded to support a revived fixed target program. In this paper we discuss a proposed new configuration that will transport beams at energies up to 50 GeV. Implementation of this configuration will require the addition of several magnets, the replacement of power supplies, and modifications to the instrumentation. Also discussed are the energy resolving capabilities of the new transport line and design options for minimizing emittance growth.
Date: August 1, 1992
Creator: Erickson, R.; Fieguth, T.; Keller, L. & Walz, D.
System: The UNT Digital Library