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Effect of Dy additions on microstructure and magnetic properties of Fe-Nd-B magnets (open access)

Effect of Dy additions on microstructure and magnetic properties of Fe-Nd-B magnets

It is shown that increasing additions of Dy causes the remanence B/sub r/ to decrease linearly. The intrinsic coercivity, iHc, increases sharply for small additions of Dy, but the increase is not proportional for higher Dy contents. The iHc increases almost linearly with the effective anisotropy field of the RE/sub 2/Fe/sub 14/B phase until the Dy content is about 10% of the total rare earth content. Above this concentration, there is strong deviation from linearity. Various types of possible concentration profiles of the substituted rare earth are suggested. It is also argued that preferential segregation of Dy to the interfaces could be beneficial in increasing the nucleation field. Morphologically there is no apparent effect of Dy on the microstructure. However, in the 5 atomic % Dy sample, Dy rich oxides were observed. It is shown through Energy Dispersive Xray Spectroscopy (EDXS) line profiling that Dy partitions preferentially into the RE/sub 2/Fe/sub 14/B phase in all the cases. No segregation of Dy to the interphase interfaces has been detected.
Date: May 1, 1987
Creator: Ramesh, R.; Thomas, G. & Ma, B.M.
Object Type: Article
System: The UNT Digital Library
Exotic damping ring lattices (open access)

Exotic damping ring lattices

This paper looks at, and compares three types of damping ring lattices: conventional, wiggler lattice with finite ..cap alpha.., wiggler lattice with ..cap alpha.. = 0, and observes the attainable equilibrium emittances for the three cases assuming a constraint on the attainable longitudinal impedance of 0.2 ohms. The emittance obtained are roughly in the ratio 4:2:1 for these cases.
Date: May 1, 1987
Creator: Palmer, Robert B.
Object Type: Article
System: The UNT Digital Library
Cryogenic detection of particles: Development effort in the United States (open access)

Cryogenic detection of particles: Development effort in the United States

The development of cryogenic detectors of particles, with emphasis on large mass devices, has been reviewed. Most groups are still tooling up and exploring basic properties of sensors. The main discussion themes are summarized and some of the early experimental results are described.
Date: May 1, 1987
Creator: Sadoulet, B.
Object Type: Article
System: The UNT Digital Library
Is Dark Matter made out of particles. Current searches and detector developments (open access)

Is Dark Matter made out of particles. Current searches and detector developments

The hypothesis that Dark Matter is made out of exotic particles is definite enough to be testable in a variety of ways. We review the first generation experiments looking for dark matter particles, using conventional techniques. They may find those particles and in any case will provide powerful constraints. We argue that in the long run, cryogenic detectors will have to be used for that type of physics, and since the European effort is covered by other speakers, we review the present developments in this area in the USA. 18 refs., 1 fig.
Date: May 1, 1987
Creator: Sadoulet, B.
Object Type: Article
System: The UNT Digital Library
Use of permanent magnets in accelerator technology: Present and future (open access)

Use of permanent magnets in accelerator technology: Present and future

This report is a collection of viewgraphs discussing accelerator magnets. Permanent magnet systems have some generic properties that, under some circumstances, make them not only mildly preferable over electromagnets, but make it possible to do things that can not be done with any other technology. After a general discussion of these generic advantages, some specific permanent magnet systems will be described. Special emphasis will be placed on systems that have now, or are likely to have in the future, a significant impact on how some materials research is conducted. 4 refs., 33 figs.
Date: May 1, 1987
Creator: Halbach, K.
Object Type: Article
System: The UNT Digital Library
Proceedings of the 1986 summer workshop on antiproton beams in the 2-10 GeV/c range (open access)

Proceedings of the 1986 summer workshop on antiproton beams in the 2-10 GeV/c range

The possibilities for building a facility for the formation spectroscopy of ''charmonium'' and the study of ''exotics'' at the AGS with high intensity antiproton beams of good resolution and enhanced purity are explored. The performance potential of a number of long beams and the AGS booster are evaluated and costs are estimated. Fluxes of several 10/sup 7/ antiprotons per pulse with purities of 5% to 99% are possible with conventional long beams. A similar total antiproton flux would be available with the Booster with no beam contamination. This could effectively be enhanced by two orders of magnitude by reducing the momentum spread in order to scan very narrow (less than 1 MeV) resonances. The maximum momentum attainable with the present Booster magnet design is 5.6 GeV/c which only reaches the Chi/sub 0/ (3415) charmonium state. Modifications are possible which would raise the maximum momentum to 6.3 GeV/c to include all states up to and including eta'/sub c/ (3590) in its range. The performance potential for this physics at the AGS is found to compare favorably with that at other laboratories with more antiprotons delivered annually, running in the post-Booster era, than at FNAL or Super-Lear with ACOL under typical scheduling …
Date: May 7, 1987
Creator: Lazarus, D. (ed.)
Object Type: Article
System: The UNT Digital Library
Geology of Platanares geothermal area, Copan, Honduras (open access)

Geology of Platanares geothermal area, Copan, Honduras

The Platanares, Copan (Honduras) geothermal area is located in a highly faulted terrain of Paleozoic(.) metamorphic rocks, Cretaceous clastic sedimentary rocks, and Tertiary volcanic rocks. All thermal manifestations are located along faults. The volcanic rocks are probably too old to represent the surface expression of an active crustal magma body. Thus, the thermal water is interpreted to be heated during deep circulation in a regime of elevated heat flow. The water chemistry suggests that the geothermal reservoir originates within the Cretaceous sedimentary sequence and that the reservoir temperature may be as high as 240/sup 0/ C. Two exploration coreholes penetrated the volcanic sequence and bottomed within Cretaceous redbeds. Well PLTG-1 is 650 m deep and flows at 3 Mw thermal from a 160/sup 0/ C permeable zone. Well PLTG-2 is 401 m deep and has a thermal gradient of 139/sup 0/ C/km. Exploration drilling is continuing, with a third corehole to be drilled in May, 1987.
Date: May 1, 1987
Creator: Heiken, G.; Duffield, W.; Wohletz, K.; Priest, S.; Ramos, N.; Flores, W. et al.
Object Type: Article
System: The UNT Digital Library
New data for aerosols generated by releases of pressurized powders and solutions in static air (open access)

New data for aerosols generated by releases of pressurized powders and solutions in static air

Safety assessments and environmental impact statements for nuclear fuel cycle facilities require an estimate of potential airborne releases. Aerosols generated by accidents are being investigated by Pacific Northwest Laboratory to develop radioactive source-term estimation methods. Experiments measuring the mass airborne and particle size distribution of aerosols produced by pressurized releases were run. Carbon dioxide was used to pressurize uranine solutions to 50, 250, and 500 psig before release. The mass airborne from these experiments was higher than for comparable air-pressurized systems, but not as great as expected based on the amount of gas dissolved in the liquid and the volume of liquid ejected from the release equipment. Flashing sprays of uranine at 60, 125, and 240 psig produced a much larger source term than all other pressurized releases performed under this program. Low-pressure releases of depleted uranium dioxide at 9, 17.5, and 24.5 psig provided data in the energy region between 3-m spills and 50-psig pressurized releases.
Date: May 1, 1987
Creator: Ballinger, M. Y.; Sutter, S. L. & Hodgson, W. H.
Object Type: Report
System: The UNT Digital Library
High dose uranium ion implantation into silicon (open access)

High dose uranium ion implantation into silicon

Implantation of uranium ions into silicon to a maximum dose of 6 x 10/sup 16/ atoms/cm/sup 2/, with a maximum concentration of 6 x 10/sup 21/ atoms/cm/sup 3/, has been carried out. This concentration corresponds to 12 at. % of uranium in the silicon host material. The implanted uranium content was measured by Rutherford backscattering and confirmed by a measurement of the alpha-particle activity of the buried uranium layer. The range and straggling of the uranium, and sputtering of the silicon target by uranium, were measured and are compared with theoretical estimates. The implantation was performed at an ion mean energy of 157 keV using a new kind of high current metal ion source.
Date: May 1, 1987
Creator: Brown, I.G.; Galvin, J.E. & Yu, K.M.
Object Type: Report
System: The UNT Digital Library
Round-robin pretest analyses of a 1:6-scale reinforced concrete containment model subject to static internal pressurization (open access)

Round-robin pretest analyses of a 1:6-scale reinforced concrete containment model subject to static internal pressurization

Analyses of a 1:6-scale reinforced concrete containment model that will be tested to failure at Sandia National Laboratories in the spring of 1987 were conducted by the following organizations in the United States and Europe: Sandia National Laboratories (USA), Argonne National Laboratory (USA), Electric Power Research Institute (USA), Commissariat a L'Energie Atomique (France), HM Nuclear Installations Inspectorate (UK), Comitato Nazionale per la ricerca e per lo sviluppo dell'Energia Nucleare e delle Energie Alternative (Italy), UK Atomic Energy Authority, Safety and Reliability Directorate (UK), Gesellschaft fuer Reaktorsicherheit (FRG), Brookhaven National Laboratory (USA), and Central Electricity Generating Board (UK). Each organization was supplied with a standard information package, which included construction drawings and actual material properties for most of the materials used in the model. Each organization worked independently using their own analytical methods. This report includes descriptions of the various analytical approaches and pretest predictions submitted by each organization. Significant milestones that occur with increasing pressure, such as damage to the concrete (cracking and crushing) and yielding of the steel components, and the failure pressure (capacity) and failure mechanism are described. Analytical predictions for pressure histories of strain in the liner and rebar and displacements are compared at locations where experimental …
Date: May 1, 1987
Creator: Clauss, D.B. (ed.)
Object Type: Report
System: The UNT Digital Library
Search for close-mass lepton pairs (L/sup -/,L/sup 0/) (open access)

Search for close-mass lepton pairs (L/sup -/,L/sup 0/)

Preliminary results are reported of a search in 207 pb/sup -1/ of MARK II PEP data at ..sqrt..s = 29 GeV for lepton pairs (L/sup -/,L/sup 0/) where the L/sup 0/ mass can be close to, but not exceed, the L/sup -/ mass. The numbers of e - ..mu.., and 3 or more charged hadrons versus isolated e or ..mu.., events are compared to Monte Carlo predictions for e/sup +/e/sup -/ ..-->.. tau/sup +/tau/sup -/, e/sup +/e/sup -/ ..-->.. q anti q, and two-virtual-photon processes. Possible residual signals for (L/sup -/,L/sup 0/) pairs are compared to Monte Carlo simulations and 2sigma confidence level limits on the L/sup -/ and L/sup 0/ masses are presented.
Date: May 1, 1987
Creator: Stoker, D. P. & Perl, M. L.
Object Type: Article
System: The UNT Digital Library
A computer program to determine the specific power of prismatic-core reactors (open access)

A computer program to determine the specific power of prismatic-core reactors

A computer program has been developed to determine the maximum specific power for prismatic-core reactors as a function of maximum allowable fuel temperature, core pressure drop, and coolant velocity. The prismatic-core reactors consist of hexagonally shaped fuel elements grouped together to form a cylindrically shaped core. A gas coolant flows axially through circular channels within the elements, and the fuel is dispersed within the solid element material either as a composite or in the form of coated pellets. Different coolant, fuel, coating, and element materials can be selected to represent different prismatic-core concepts. The computer program allows the user to divide the core into any arbitrary number of axial levels to account for different axial power shapes. An option in the program allows the automatic determination of the core height that results in the maximum specific power. The results of parametric specific power calculations using this program are presented for various reactor concepts.
Date: May 1, 1987
Creator: Dobranich, D.
Object Type: Report
System: The UNT Digital Library
The influence of N-ion irradiation on superconducting TiN (open access)

The influence of N-ion irradiation on superconducting TiN

The influence of disorder on the properties of the B1 phase superconductive compound titanium nitride has been investigated. Following synthesis and characterization of thin films of TiN, the materials were disordered progressively and uniformly by irradiation with nitrogen ions. The superconducting transition temperature T/sub c/ decreased and the low temperature electrical resistivity rho increased as lattice damage was introduced. The dependence of both T/sub c/ and rho on N-ion fluence phi could be described by exponentially saturating functions of phi with similar rate constants. These constants correspond to characteristic damage energy densities of 14 and 12 eV/atom, respectively.
Date: May 1, 1987
Creator: Thompson, J. R.; Ellis, J. T.; Christen, D. K.; Sekula, S. T.; Lewis, J. D. & Williams, J. M.
Object Type: Article
System: The UNT Digital Library
Recommended Temperature Limits for Dry Storage of Spent Light Water Reactor Zircaloy-Clad Fuel Rods in Inert Gas (open access)

Recommended Temperature Limits for Dry Storage of Spent Light Water Reactor Zircaloy-Clad Fuel Rods in Inert Gas

It is concluded that the recommendation of a single-valued temperature limit of 380/sup 0/C should be replaced by multiple limits to account for variations in fuel design, burnup level, spent fuel age, and storage cask design. A single-valued limit to account for these factors would, in some situations, impose unnecessary conservatisms and, potentially, economic penalties for utilities and storage cask vendors. The technical validity and conservatism of the CSFM model should assure acceptance by the NRC for utility and cask vendor use.
Date: May 1, 1987
Creator: Levy, I. S.; Chin, B. A.; Simonen, E. P.; Beyer, C. E.; Gilbert, E. R. & Johnson, A. B., (Jr.)
Object Type: Report
System: The UNT Digital Library
A Wildlife Habitat Protection, Mitigation and Enhancement Plan for Eight Federal Hydroelectric Facilities in the Willamette River Basin: Final Report. (open access)

A Wildlife Habitat Protection, Mitigation and Enhancement Plan for Eight Federal Hydroelectric Facilities in the Willamette River Basin: Final Report.

The development and operation of eight federal hydroelectric projects in the Willamette River Basin impacted 30,776 acres of prime wildlife habitat. This study proposes mitigative measures for the losses to wildlife and wildlife habitat resulting from these projects, under the direction of the Columbia River Basin (CRB) Fish and Wildlife Program. The CRB Fish and Wildlife Program was adopted in 1982 by the Northwest Power Planning Council, pursuant to the Northwest Power Planning Act of 1980. The proposed mitigation plan is based on the findings of loss assessments completed in 1985, that used a modified Habitat Evaluation Procedure (HEP) to assess the extent of impact to wildlife and wildlife habitat, with 24 evaluation species. The vegetative structure of the impacted habitat was broken down into three components: big game winter range, riparian habitat and old-growth forest. The mitigation plan proposes implementation of the following, over a period of 20 years: (1) purchase of cut-over timber lands to mitigate, in the long-term, for big game winter range, and portions of the riparian habitat and old-growth forest (approx. 20,000 acres); (2) purchase approximately 4,400 acres of riparian habitat along the Willamette River Greenway; and (3) three options to mitigate for the outstanding …
Date: May 1, 1987
Creator: Preston, S. K.
Object Type: Report
System: The UNT Digital Library
Probability of causation: Implications for radiological protection and dose limitation (open access)

Probability of causation: Implications for radiological protection and dose limitation

This report on the probability of causation of radiation-induced cancer is an attempt to bring together biology, chemistry, physics and statistics to calculate a value in the form of a ratio expressed as a percentage. In involves the interactions of numerous cancer risk factors, and all are fraught with technical difficulties and uncertainties. It is a computational approach to a societal problem that should be resolved in the political arena by men and women of government and law. But, it must be examined, because at the present, we have no reasonable method to explain the complexity of the mechanism of radiation-induced cancer and the probability of injury to an individual exposed in the past to ionizing radiation, and because society does not know how to compensate such a person who may have been injured by radiation, and particularly low-level radiation. Five questions are discussed that concern probability of causation of radiation-induced cancer. First, what is it and how can we best define the concept Second, what are the methods of estimation and cancer causation Third, what are the uncertainties involved Fourth, what are the strengths and limitation of the computational approach And fifth, what are the implications for radiological protection …
Date: May 1, 1987
Creator: Fabrikant, Jacob I.
Object Type: Article
System: The UNT Digital Library
Multifragmentation and flow in central collisions of heavy systems (open access)

Multifragmentation and flow in central collisions of heavy systems

Experimental results are presented on the production of light particles (A < 5) and intermediate mass fragments (6 < A < 18) over a large solid angle. The reactions 200 MeV/n Au + Au amd Au + Fe were studied to provide information on multifragmentation processes and collective flow. 20 refs., 6 figs.
Date: May 1, 1987
Creator: Harris, J. W.; Jacak, B. V.; Kampert, K. H.; Claesson, G.; Doss, K. G. R.; Ferguson, R. et al.
Object Type: Article
System: The UNT Digital Library
Formation and maintenance of a tokamak discharge via dc helicity injection (open access)

Formation and maintenance of a tokamak discharge via dc helicity injection

Formation and maintenance of a tokamak discharge utilizing helicity injection via a dc low-energy electron beam has been observed in the Current Drive Experiment (CDX). As the plasma current increases, the discharge changes from a configuration dictated by the externally imposed vacuum poloidal fields into a steady-state configuration dominated by the self-generated poloidal field. This configuration was maintained for 60 msec (the time limited by the cathode bias supply), equivalent to more than 400 resistive decay periods. Viewed tangentially, the plasma spontaneously evolves into a circular shape. Measurement of the poloidal magnetic field reveals a considerably peaked current profile, indicating strong radially inward current pinching. The measured q-profile has a typical value of 10 at the plasma edge and reaches a minimum of 4 at the magnetic axis. The line-averaged density profile is also highly peaked, reaching anti n/sub e/ = 2 x 10/sup 13/ cm/sup -3/ for the central chord. Measurements of plasma conductivity indicate that T/sub e/ rises to approx.25 eV, while the spectroscopically observed average ion temperature increases from approx.1 eV to approx.15 eV as the current increases. These results indicate that the current system evolves toward a tokamak configuration even though the current drive is noninductive.
Date: May 1, 1987
Creator: Ono, M.; Greene, G. J.; Darrow, D.; Forest, C.; Park, H. & Stix, T. H.
Object Type: Report
System: The UNT Digital Library
Performance comparisons of low emittance lattices (open access)

Performance comparisons of low emittance lattices

In this paper, the results of a performance analysis of several low emittance electron storage ring lattices provided by various members of the Lattice Working Group are presented. Altogether, four lattices were investigated. There are two different functions being considered for the low beam emittance rings discussed here. The first is to serve as a Damping Ring (DR), i.e., to provide the emittance damping required for a high energy linear collider. The second is to provide beams for a short wavelength Free Electron Laser (FEL), which is envisioned to operate in the wavelength region near 40 A.
Date: May 1, 1987
Creator: Delahaye, J. P. & Zisman, M. S.
Object Type: Article
System: The UNT Digital Library
Resonant Alfven wave instabilities driven by streaming fast particles (open access)

Resonant Alfven wave instabilities driven by streaming fast particles

A plasma simulation code is used to study the resonant interactions between streaming ions and Alfven waves. The medium which supports the Alfven waves is treated as a single, one-dimensional, ideal MHD fluid, while the ions are treated as kinetic particles. The code is used to study three ion distributions: a cold beam; a monoenergetic shell; and a drifting distribution with a power-law dependence on momentum. These distributions represent: the field-aligned beams upstream of the earth's bow shock; the diffuse ions upstream of the bow shock; and the cosmic ray distribution function near a supernova remnant shock. 92 refs., 31 figs., 12 tabs.
Date: May 8, 1987
Creator: Zachary, A.
Object Type: Report
System: The UNT Digital Library
Design charts for spacing of vacuum line supports (open access)

Design charts for spacing of vacuum line supports

This paper presents design tables and graphs to aid engineers and designers in the selection of support spacing for vacuum beam lines and other vacuum pipes. This data applies to support spacing for thin wall pipes and tubes under an internal vacuum (or open to atmosphere) and subject to external atmospheric pressure. Data is generated from the equations for a simply supported thin walled pipe or tube of circular cross section. These tables and graphs indicate what the minimum spacing of supports is for a pipe or tube of a given radius and supply data for carbon steel, stainless steel, aluminum and copper materials. The wall thickness of the pipe and tube is limited to 1/10 of the pipe radium (T << R/10). A thickness of R/10 results in a decrease in the length values in the attached tables of 10%, whereas a thickness of R/100 results in a decrease in the length values in the attached tables of 1%. Snow loads, wind loads, equipment loads, etc. are not included in the tables and graphs. This data is applicable for vacuum pipes or tubes under its own static deed weight.
Date: May 4, 1987
Creator: Western, J.L. & Krempetz, K.J.
Object Type: Report
System: The UNT Digital Library
Alarm points for fixed oxygen monitors (open access)

Alarm points for fixed oxygen monitors

Oxygen concentration monitors were installed in a vault where numerous pipes carried inert cryogens and gases to the Mirror Fusion Test Facility (MFTF-B) experimental vessel at Lawrence Livermore National Laboratory (LLNL). The problems associated with oxygen-monitoring systems and the reasons why such monitors were installed were reviewed. As a result of this review, the MFTF-B monitors were set to sound an evacuation alarm when the oxygen concentration fell below 18%. We chose the 18% alarm criterion to minimize false alarms and to allow time for personnel to escape in an oxygen-deficient environment.
Date: May 1, 1987
Creator: Miller, G.C.
Object Type: Article
System: The UNT Digital Library
Gaining control over rare earth valence fluctuations (open access)

Gaining control over rare earth valence fluctuations

This paper briefly deals with the problem of narrow band materials. It addresses a new theoretical approach to the fluctuation of valence electrons in rare earth elements. It is believed that the phenomena of interest arize from an instability of the partially filled d or f shell of certain atoms when they are put into a metallic host. The theoretical models which dominate the scene work with two local d or f states on one hand and a structureless sea of free conduction electrons on the other. This procedure ignores at least half of the essential physics; the other held is kept alive in the term valence fluctuation. Basically, what the prevalent models ignore is that, in all these systems, the entire atoms as the source of the anomalies are being dealt with, not just their f shells. In other words, there is important structure in the sea of conduction electrons.
Date: May 31, 1987
Creator: Wohlleben, D.
Object Type: Article
System: The UNT Digital Library
NULLJOB product (open access)

NULLJOB product

The ever increasing demand for more CPU cycles for data analysis on our Central VAX Cluster led us to investigate new ways to utilize more fully the resources that were available. A review of the experiment and software development VAX systems on site revealed many unused computing cycles. Furthermore, these systems were all connected by DECnet which would allow easy file transfer and remote batch job submission. A product was developed to allow jobs to be submitted on the Central VAX Cluster but actually to be run on one of the remote systems. The processing of the jobs was arranged, to the greatest extent possible, to be transparent to the user and to have minimal impact on both the Central VAX Cluster and remote systems.
Date: May 1, 1987
Creator: Hughart, N. & Ritchie, D.
Object Type: Article
System: The UNT Digital Library