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712 Matching Results

Start Over Year 1999 Day 29th

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Results: 1 - 24 of 712 next

(open access)

Radiation environment resulting from Main Injector beam extraction to the NuMI beam line

A 120 GeV Main Injector proton beam will be delivered to the NuMI beam line at Fermilab at the rate of 3.7x 10{sup 20} per year. Realistic Monte Carlo simulations have been performed to examine the radiation environment in the beam extraction system and NuMI beam line elements. A complete 3-D model of the 160 meter extraction region has been implemented utilizing the computer code MARS. The model includes a description of the field of the electrostatic septa and POISSON calculated field maps of the Lambertson magnets and the other lattice components in the area. The beam element alignment and the source term have been simulated using the code STRUCT. Results on beam losses in the system, energy deposition in the core elements and residual dose rates on the components are presented.

Date: April 29, 1999

Creator: A.I. Drozhdin, P.W. Lucas, N.V. Mokhov, C.D. Moore and S.I. Striganov

Object Type: Article

System: The UNT Digital Library

(open access)

Antireflection Coating Design for Series Interconnected Multi-Junction Solar Cells

AR coating design for multi-junction solar cells can be more challenging than in the single junction case. Reasons for this are discussed. Analytical expressions used to optimize AR coatings for single junction solar cells are extended for use in monolithic, series interconnected multi-junction solar cell AR coating design. The result is an analytical expression which relates the solar cell performance (through J{sub SC}) directly to the AR coating design through the device reflectance. It is also illustrated how AR coating design can be used to provide an additional degree of freedom for current matching multi-junction devices.

Date: November 29, 1999

Creator: AIKEN,DANIEL J.

Object Type: Article

System: The UNT Digital Library

(open access)

Oak Ridge Isotope Products and Services - Current and Expected Supply and Demand

Oak Ridge National Laboratory (ORNL) has been a major center of isotope production research, development, and distribution for over 50 years. Currently, the major isotope production activities include (1) the production of transuranium element radioisotopes, including 252 Cf; (2) the production of medical and industrial radioisotopes; (3) maintenance and expansion of the capabilities for production of enriched stable isotopes; and, (4) preparation of a wide range of custom-order chemical and physical forms of isotope products, particularly in accelerator physics research. The recent supply of and demand for isotope products and services in these areas, research and development (R&D), and the capabilities for future supply are described in more detail below. The keys to continuing the supply of these important products and services are the maintenance, improvement, and potential expansion of specialized facilities, including (1) the High Flux Isotope Reactor (HFIR), (2) the Radiochemical Engineering Development Center (REDC) and Radiochemical Development Laboratory (RDL) hot cell facilities, (3) the electromagnetic calutron mass separators and the plasma separation process equipment for isotope enrichment, and (4) the Isotope Research Materials Laboratory (IRML) equipment for preparation of specialized chemical and physical forms of isotope products. The status and plans for these ORNL isotope production facilities …

Date: August 29, 1999

Creator: Aaron, W. S.; Alexander, C. W.; Cline, R. L.; Collins, E. D.; Klein, J. A.; Knauer, J. B., Jr. et al.

Object Type: Article

System: The UNT Digital Library

(open access)

Low Speed Carbon Deposition Process for Hermetic Optical Fibers

For optical fibers used in adverse environments, a carbon coating is frequently deposited on the fiber surface to prevent water and hydrogen ingression that lead respectively to strength degradation through fatigue and hydrogen-induced attenuation. The deposition of a hermetic carbon coating onto an optical fiber during the draw process holds a particular challenge when thermally-cured specialty coatings are subsequently applied because of the slower drawing rate. In this paper, we report on our efforts to improve the low-speed carbon deposition process by altering the composition and concentration of hydrocarbon precursor gases. The resulting carbon layers have been analyzed for electrical resistance, Raman spectra, coating thickness, and surface roughness, then compared to strength data and dynamic fatigue behavior.

Date: September 29, 1999

Creator: Abramczyk, Jaroslaw; Arthur, Sara E.; Tallant, David R.; Hikansson, Adam S.; Lindholm, Eric A. & Lo, Jie

Object Type: Article

System: The UNT Digital Library

(open access)

Tunable laser action at 4.0 microns from Fe:ZnSe

None

Date: January 29, 1999

Creator: Adams, J. J.; Page, R. H.; Bibeau, C. & Payne, S. A.

Object Type: Article

System: The UNT Digital Library

(open access)

Assessing Sources of Stress to Aquatic Ecosystems: Using Biomarkers and Bioindicators to Characterize Exodure-Response Profiles of Anthropogenic Activities

Establishing causal relationships between sources of environmental stressors and aquatic ecosystem health if difficult because of the many biotic and abiotic factors which can influence or modify responses of biological systems to stress, the orders of magnitude involved in extrapolation over both spatial and temporal scales, and compensatory mechanisms such as density-dependent responses that operate in populations. To address the problem of establishing causality between stressors and effects on aquatic systems, a diagnostic approach, based on exposure-response profiles for various anthropogenic activities, was developed to help identify sources of stress responsible for effects on aquatic systems at ecological significant levels of biological organization (individual, population, community). To generate these exposure-effects profiles, biomarkers of exposure were plotted against bioindicators of corresponding effects for several major anthropogenic activities including petrochemical , pulp and paper, domestic sewage, mining operations, land-development activities, and agricultural activities. Biomarkers of exposure to environmental stressors varied depending on the type of anthropogenic activity involved. Bioindicator effects, however, including histopathological lesions, bioenergetic status, individual growth, reproductive impairment, and community-level responses were similar among many of the major anthropogenic activities. This approach is valuable to help identify and diagnose sources of stressors in environments impacted by multiple stressors. By identifying …

Date: March 29, 1999

Creator: Adams, S.M.

Object Type: Article

System: The UNT Digital Library

(open access)

Studies of ferroelectric heterostructure thin films, interfaces, and device-related processes via in situ analytical techniques.

The science and technology of ferroelectric thin films has experienced an explosive development during the last ten years. Low-density non-volatile ferroelectric random access memories (NVFRAMS) are now incorporated in commercial products such as ''smart cards'', while high permittivity capacitors are incorporated in cellular phones. However, substantial work is still needed to develop materials integration strategies for high-density memories. We have demonstrated that the implementation of complementary in situ characterization techniques is critical to understand film growth and device processes relevant to device development. We are using uniquely integrated time of flight ion scattering and recoil spectroscopy (TOF-ISARS) and spectroscopic ellipsometry (SE) techniques to perform in situ, real-time studies of film growth processes in the high background gas pressure required to growth ferroelectric thin films. TOF-ISARS provides information on surface processes, while SE permits the investigation of buried interfaces as they are being formed. Recent studies on SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) and Ba{sub x}Sr{sub 1{minus}x}TiO{sub 3} (BST) film growth and interface processes are discussed. Direct imaging of ferroelectric domains under applied electric fields can provide valuable information to understand domain dynamics in ferroelectric films. We discuss results of piezoresponse scanning force microscopy (SFM) imaging for nanoscale studies of polarization reversal …

Date: June 29, 1999

Creator: Aggarwal, S.; Auciello, O.; Dhote, A. M.; Gao, Y.; Gruen, D. M.; Im, J. et al.

Object Type: Article

System: The UNT Digital Library

(open access)

High Intensity Performance of the Brookhaven AGS.

The Brookhaven AGS provides 24 GeV protons for a multi-user program of fixed-target high energy physics experiments, such as the study of extremely rare Kaon decays. Up to 7 x 10{sup 13} protons are slowly extracted over 2.2 seconds each 5.1 seconds. The muon storage ring of the g-2 experiment is supplied with bunches of 7 x 10{sup 12} protons. Since the completion of the a 1.9 GeV Booster synchrotron and installation of a new high-power rf system and transition jump system in the AGS various modes of operation have been explored to overcome space charge limits and beam instabilities at these extreme beam intensities. Experiments have been done using barrier cavities to enable accumulation of debunched beam in the AGS as a potential path to significantly higher intensities. We report on the present understanding of intensity limitations and prospects for overcoming them.

Date: March 29, 1999

Creator: Ahrens, L. A.; Alessi, J.; Blaskiewicz, M.; Brennan, J. M.; Brown, K.; Gardner, C. et al.

Object Type: Article

System: The UNT Digital Library

(open access)

Performance of the AGS Transition Jump System.

The transition jump system has been indispensable to the high intensity proton operation of the AGS complex. Nevertheless, transition crossing remains one of the major hurdles as the accelerator complex intensity is pushed upward. To enhance the performance of the system ''quadrupole pumping'' in the Booster is used to minimize the necessary longitudinal dilution of the beam on the AGS injection porch. During the transition jump sextupole correctors at strategic locations are pulsed to minimize the effects of the chromatic non-linearity of the jump system. The available instrumentation for diagnosing the performance of the system will be described, along with installed hardware to counter the non-linear effects of the transition jump system.

Date: March 29, 1999

Creator: Ahrens, L. A.; Brennan, J. M.; Glenn, J. W.; Roser, T. & Van Asselt, W. K.

Object Type: Article

System: The UNT Digital Library

(open access)

AGS Resonant Extraction With High Intensity Beams.

The Brookhaven AGS third integer resonant extraction system allows the AGS to provide high quality, high intensity 25.5 GeV/c proton beams simultaneously to four target stations and as many as 8 experiments. With the increasing intensities (over 7 x 10{sup 13} protons/pulse) and associated longer spill periods (2.4 to 3 seconds long), we continue to run with low losses and high quality low modulation continuous current beams.[1] Learning to extract and transport these higher intensity beams has required a process of careful modeling and experimentation. We have had to learn how to correct for various instabilities and how to better match extraction and the transport lines to the higher emittance beams being accelerated in the AGS. Techniques employed include ''RF'' methods to smooth out momentum distributions and fine structure. We will present results of detailed multi-particle tracking modeling studies which enabled us to develop a clear understanding of beam loss mechanisms in the transport and extraction process. We will report on our status, experiences, and the present understanding of the intensity limitations imposed by resonant extraction and transport to fixed target stations.

Date: March 29, 1999

Creator: Ahrens, L.; Brown, K.; Glenn, J. W.; Roser, T.; Tsoupas, N. & Vanasselt, W.

Object Type: Article

System: The UNT Digital Library

(open access)

Broadly Turnable Pump-Resonant Diode-Pumped CW PPLN OPO

We have observed low threshold operation of a broadly tunable (2.18-3.4 µm) pump-resonant cw periodically poled lithium niobate (PPLN) optical parametric oscillator (OPO). When pumped at 806 nm with 410 mW from a custom-built diode laser the OPO generated 20 mW of idler output at 3.3 µm.

Date: April 29, 1999

Creator: Alford, W.J.; Bowers, Mark S.; Raymond, T.D. & Seamans, J.F.

Object Type: Article

System: The UNT Digital Library

(open access)

The Oklahoma Daily (Norman, Okla.), Vol. 83, No. 94, Ed. 1 Friday, January 29, 1999

Student newspaper of the University of Oklahoma in Norman, Oklahoma that includes national, local, and campus news along with advertising.

Date: January 29, 1999

Creator: Allam, Heather

Object Type: Newspaper

System: The Gateway to Oklahoma History

(open access)

The Oklahoma Daily (Norman, Okla.), Vol. 83, No. 128, Ed. 1 Monday, March 29, 1999

Student newspaper of the University of Oklahoma in Norman, Oklahoma that includes national, local, and campus news along with advertising.

Date: March 29, 1999

Creator: Allam, Heather

Object Type: Newspaper

System: The Gateway to Oklahoma History

(open access)

The Oklahoma Daily (Norman, Okla.), Vol. 83, No. 153, Ed. 1 Thursday, April 29, 1999

Student newspaper of the University of Oklahoma in Norman, Oklahoma that includes national, local, and campus news along with advertising.

Date: April 29, 1999

Creator: Allam, Heather

Object Type: Newspaper

System: The Gateway to Oklahoma History

(open access)

Enhancing the Performances of ECR Ion Sources

The performances of ECR ion sources can be enhanced in the spatial domain by tailoring the central magnetic field so that it is uniformly distributed over a large plasma volume and is of magnitude so as to be in resonance with single frequency microwave radiation. Analogously, the performances of conventional minimum-B ECR ion sources can be enhanced in the frequency domain by injecting multiple discrete frequency or broadband microwave radiation into their plasma volumes. In this report, examples of both the spatial-and frequency-domain techniques will be given. For example, the design aspects of an all permanent-magnet ''volume-type'' (spatial-domain) ECR ion source will be described and the effects of injecting multiple frequencies (frequency-domain) on the charge-state-distributions extracted from a conventional minimum-B ECR ion source will be presented.

Date: March 29, 1999

Creator: Alton, G. D. & Liu, Y.

Object Type: Article

System: The UNT Digital Library

(open access)

A High-Temperature, "Volume-Type" ECR Ion Source for RIB Generation

A high temperature, low-charge-state, "volume-type" source has been designed for use in the nuclear physics and nuclear astrophysics research radioactive ion beam (RIB) programs at the Holifield Radioactive Ion beam Facility (HRIBF). The source utilizes electromagnetic coils to generate a large and uniformly distributed central magnetic field with magnitude (875 G) chosen to be in electron-cyclotron-resonance (ECR) with single- frequency (2.45 GHz) microwave radiation. Among the features of the source includti a variable mirror-ratio at ion extraction as required for optimizing low-charge state ion beam generation, a right-hand, circularly-polarized RF injection system to overcome the relatively-low, cutoff-density, (nC - 7.4x10'0/cm3) associated with the use of 2.45 GHz microwave radiatiom, and a high temperature, Ir- or Re-coated-Ta plasma chamber to reduce the residence times of radioactive species that are adsorbed on the walls of the chamber. No provisions are made for radial plasma confinement due to the sensitivity of permanent magnets to degradation by the huge fluxes of neutrons incumbent during target irradiation, routinely used for this purpose. Aspects of the design features of the source are described in this report.

Date: March 29, 1999

Creator: Alton, G. D.; Liu, Y.; Reed, C. A.; Williams, C. & Zhang, T.

Object Type: Article

System: The UNT Digital Library

(open access)

Thermoacoustic Liquefaction of Coal Mine Methane to Produce Lng for Heavy Vehicle Applicaitons

This report describes the activity undertaken by the project members under MORGANTOWN ENERGY TECHNOLOGY CENTER (METC) contract No. DE-AC21-95MC32185 to develop a project that will provide a commercial use for Coal Mine Methane (CMM). In particular, the report describes a project to convert CMM into Liquefied Natural Gas (LNG) and to market that LNG to the transportation sector in and around the I-79 corridor near Morgantown, West Virginia. The report discusses the sources of CMM and provides estimates of the extent of the resource specifically dedicated to the project. It discusses the novel refrigeration technology that will be employed to convert the CMM to LNG and the gas conditioning technology that will be used to bring the raw CMM up to cryogenic processing specifications. Summary capital and operating cost estimates are furnished for the project and specific monetary and schedule requirements are identified so the project can be examined in its entirety. The report discusses the immediate market potential for the successful commercial sale of LNG into the nearby market and provides estimates of future market penetration into local, regional and wider markets. Lastly, the report comments on the environmental effects of the project and extrapolates these benefits to future …

Date: October 29, 1999

Creator: Aminian, Kashi; English, Lloyd; Patchen, Douglas; Siriwardane, Hema; Estes, Charles D. & Zahradnik, Raymond L.

Object Type: Report

System: The UNT Digital Library

(open access)

Federal Emergency Management Information System (FEMIS) Data Management Guide for FEMIS Version 1.4.6

The Federal Emergency Management Information System (FEMIS) is an emergency management planning and response tool that was developed by the Pacific Northwest National Laboratory (PNNL) under the direction of the U.S. Army Chemical Biological Defense Command. The FEMIS System Administration Guide provides information necessary for the system administrator to maintain the FEMIS system. The FEMIS system is designed for a single Chemical Stockpile Emergency Preparedness Program (CSEPP) site that has multiple Emergency Operations Centers (EOCs). Each EOC has personal computers (PCs) that emergency planners and operations personnel use to do their jobs. These PCs are corrected via a local area network (LAN) to servers that provide EOC-wide services. Each EOC is interconnected to other EOCs via a Wide Area Network (WAN). Thus, FEMIS is an integrated software product that resides on client/server computer architecture. The main body of FEMIS software, referred to as the FEMIS Application Software, resides on the PC client(s) and is directly accessible to emergency management personnel. The remainder of the FEMIS software, referred to as the FEMIS Support Software, resides on the UNIX server. The Support Software provides the communication data distribution and notification functionality necessary to operate FEMIS in a networked, client/server environment.

Date: June 29, 1999

Creator: Angel, L. K.; Bower, J. C.; Burnett, R. A.; Downing, T. R.; Fangman, P. M.; Hoza, M. et al.

Object Type: Report

System: The UNT Digital Library

(open access)

Non-Economic Determinants of Energy Use in Rural Areas of South Africa

This project will begin to determine the forces and dimensions in rural energy-use patterns and begin to address policy and implementation needs for the future. This entails: Forecasting the social and economic benefits that electrification is assumed to deliver regarding education and women's lives; Assessing negative perceptions of users, which have been established through the slow uptake of electricity; Making recommendations as to how these perceptions could be addressed in policy development and in the continuing electrification program; Making recommendations to policy makers on how to support and make optimal use of current energy-use practices where these are socio-economically sound; Identifying misinformation and wasteful practices; and Other recommendations, which will significantly improve the success of the rural electrification program in a socio-economically sound manner, as identified in the course of the work.

Date: March 29, 1999

Creator: Annecke, W. (Energy and Development Research Center, University of Cape Town, South Africa)

Object Type: Report

System: The UNT Digital Library

(open access)

New VOF interface capturing and reconstruction algorithms

Several new methods are presented for the capturing and tracking of material boundary interfaces. All methods belong to the general Volume Of Fluid (VOF) approach, and vary from simple flow aligned algorithms to more complex geometric modeling. The performance of the different methods is evaluated by solving the advection equations for a variant of the canonical multi-fluid ''ball & jacks'' problem.

Date: June 29, 1999

Creator: Anninos, P

Object Type: Report

System: The UNT Digital Library

[Photograph 2012.201.B0964.0013]

Photograph used for a newspaper owned by the Oklahoma Publishing Company. Caption: "Show place of the Southwest, as the Criterion Theatre was lauded in the days before movies could talk, faces a eulogy from the wrecking ball as it is razed to make for downtown urban renewal projects."

Date: January 29, 1999

Creator: Argo, Jim

Object Type: Photograph

System: The Gateway to Oklahoma History