Language

GaInNAs Laser Gain (open access)

GaInNAs Laser Gain

The optical gain spectra for GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of the lasing threshold current density of GaInNAs/GaAs quantum well structures.
Date: May 23, 2000
Creator: Chow, Weng W.; Jones, Eric D.; Modine, Normand A.; Kurtz, Steven R. & Allerman, Andrew A.
Object Type: Article
System: The UNT Digital Library
Intense Ion Beam for Warm Dense Matter Physics (open access)

Intense Ion Beam for Warm Dense Matter Physics

The Neutralized Drift Compression Experiment (NDCX) at Lawrence Berkeley National Laboratory is exploring the physical limits of compression and focusing of ion beams for heating material to warm dense matter (WDM) and fusion ignition conditions. The NDCX is a beam transport experiment with several components at a scale comparable to an inertial fusion energy driver. The NDCX is an accelerator which consists of a low-emittance ion source, high-current injector, solenoid matching section, induction bunching module, beam neutralization section, and final focusing system. The principal objectives of the experiment are to control the beam envelope, demonstrate effective neutralization of the beam space-charge, control the velocity tilt on the beam, and understand defocusing effects, field imperfections, and limitations on peak intensity such as emittance and aberrations. Target heating experiments with space-charge dominated ion beams require simultaneous longitudinal bunching and transverse focusing. A four-solenoid lattice is used to tune the beam envelope to the necessary focusing conditions before entering the induction bunching module. The induction bunching module provides a head-to-tail velocity ramp necessary to achieve peak axial compression at the desired focal plane. Downstream of the induction gap a plasma column neutralizes the beam space charge so only emittance limits the focused beam …
Date: May 23, 2008
Creator: Coleman, Joshua Eugene
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Semileptonic B decays at BaBar (open access)

Semileptonic B decays at BaBar

This paper summarizes the content of a talk given by the author at the Lake Louise Winter Institute, on February 21st 2007. It presents recent measurements of the rates for semileptonic B decays using data collected by the BaBar detector at the PEP-II asymmetric-energy collider at the Stanford Linear Accelerator Center.
Date: May 23, 2007
Creator: Cote, D. & U., /Montreal
Object Type: Article
System: The UNT Digital Library
Progress in studies of Electron-Cloud-Induced Optics Distortions at CESRTA (open access)

Progress in studies of Electron-Cloud-Induced Optics Distortions at CESRTA

The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent betatron tune shifts for a variety of electron and positron beam energies, bunch population levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced lowenergy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation program packages has allowed determination of the sensitivity of these measurements to physical parameters characterizing the synchrotron radiation flux, the production of photoelectrons on the vacuum chamberwall, the beam emittance, lattice optics,and the secondary-electron yield model. We report on progress in understanding the cloud buildup and decay mechanisms in magnetic fields and in field-free regions, addressing quantitatively the precise determination of the physical parameters of the modeling. Validation of these models will serve as essential input in the design of damping rings for future high-energy linear colliders.
Date: May 23, 2010
Creator: Crittenden, J. A.; Calvey, J. R.; Dugan, G. F.; Kreinick, D. L.; Leong, Z.; Livezey, J. A. et al.
Object Type: Article
System: The UNT Digital Library
Evaluation of electric vehicle production and operating costs (open access)

Evaluation of electric vehicle production and operating costs

This report presents an analysis of the initial cost of electric vehicles (EVs). The manufacturing and retail cost structure of mature conventional vehicles produced at high volume is analyzed first, and the contributions by various cost categories to vehicle price are estimated. The costs are then allocated to such vehicle component groups as body, chassis, and powertrain. The similarities and differences among various component systems are reviewed. In electric vehicles, an electric drive replaces the conventional powertrain, and a battery pack replaces the fuel system. Three types of traction motors are reviewed, and their cost in high-volume production is analyzed. Various components of the motor and controller package are analyzed, and their representative costs are summarized. Four types of EV batteries are reviewed, and their costs are presented. Various alternatives for the low-, medium-, and high-volume production of EVs are evaluated, and some sample costs are presented. A methodology that estimates initial and operating costs on the basis of this analysis is presented. The methodology also estimates the average lifetime cost of owning and operating an electric vehicle.
Date: May 23, 2000
Creator: Cuenca, R. M.; Gaines, L. L. & Vyas, A. D.
Object Type: Report
System: The UNT Digital Library
25 Process Assistance. For Period of May 2, 1955 to May 13, 1955 (open access)

25 Process Assistance. For Period of May 2, 1955 to May 13, 1955

None
Date: May 23, 1955
Creator: Culler, F L
Object Type: Report
System: The UNT Digital Library
Computation of the bounce-average code (open access)

Computation of the bounce-average code

The bounce-average computer code simulates the two-dimensional velocity transport of ions in a mirror machine. The code evaluates and bounce-averages the collision operator and sources along the field line. A self-consistent equilibrium magnetic field is also computed using the long-thin approximation. Optionally included are terms that maintain ..mu.., J invariance as the magnetic field changes in time. The assumptions and analysis that form the foundation of the bounce-average code are described. When references can be cited, the required results are merely stated and explained briefly. A listing of the code is appended.
Date: May 23, 1977
Creator: Cutler, T. A.; Pearlstein, L. D. & Rensink, M. E.
Object Type: Report
System: The UNT Digital Library
Zero-flux planes, flux reversals and diffusion paths in ternary and quaternary diffusion (open access)

Zero-flux planes, flux reversals and diffusion paths in ternary and quaternary diffusion

During isothermal multicomponent diffusion, interdiffusion fluxes of individual components can go to zero at zero-flux planes (ZFP) and exhibit flux reversals from one side to the other of such planes. Interdiffusion fluxes as well as the locations and compositions of ZFPs for components are determined directly from the concentration profiles of diffusion couples without the need for prior knowledge of interdiffusion coefficients. The development and identification of ZFPs is reviewed with the aid of single phase and two-phase diffusion couples investigated in the Cu-Ni-Zn system at 775/sup 0/C. ZFP locations in the diffusion zone nearly correspond to sections where the activity of a component is the same as its activity in either of the terminal alloys of a couple. Path slopes at ZFPs are uniquely dictated by the atomic mobility and thermodynamic data for the components. Discontinuous flux reversals for the components can also occur at interfaces in multiphase couples. Identification of ZFPs is also presented for diffusion in the Cu-Ni-Zn-Mn quaternary system. Analytical representation of diffusion paths for both ternary and quaternary diffusion couples is presented with the aid of characteristic path parameters.
Date: May 23, 1986
Creator: Dayananda, M.A.
Object Type: Report
System: The UNT Digital Library
Hybrid Paper/Electronic Archival Collecting, Processing, and Reference: A View from SLAC (open access)

Hybrid Paper/Electronic Archival Collecting, Processing, and Reference: A View from SLAC

Real-time archiving of mixed paper and digital collections presents challenges not encountered in the primarily paper environment. A few recent examples from the archives of the Stanford Linear Accelerator Center highlight obstacles encountered, and attempted and contemplated solutions.
Date: May 23, 2008
Creator: Deken, Jean M.
Object Type: Article
System: The UNT Digital Library
Generic Degraded Congiguration Probability Analysis for DOE Codisposal Waste Package (open access)

Generic Degraded Congiguration Probability Analysis for DOE Codisposal Waste Package

In accordance with the technical work plan, ''Technical Work Plan For: Department of Energy Spent Nuclear Fuel Work Packages'' (CRWMS M&O 2000c), this Analysis/Model Report (AMR) is developed for the purpose of screening out degraded configurations for U.S. Department of Energy (DOE) spent nuclear fuel (SNF) types. It performs the degraded configuration parameter and probability evaluations of the overall methodology specified in the ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2000, Section 3) to qualifying configurations. Degradation analyses are performed to assess realizable parameter ranges and physical regimes for configurations. Probability calculations are then performed for configurations characterized by k{sub eff} in excess of the Critical Limit (CL). The scope of this document is to develop a generic set of screening criteria or models to screen out degraded configurations having potential for exceeding a criticality limit. The developed screening criteria include arguments based on physical/chemical processes and probability calculations and apply to DOE SNF types when codisposed with the high-level waste (HLW) glass inside a waste package. The degradation takes place inside the waste package and is long after repository licensing has expired. The emphasis of this AMR is on degraded configuration screening and the probability analysis is one of …
Date: May 23, 2001
Creator: Deng, S.F.A.; Saglam, M. & Gratton, L.J.
Object Type: Report
System: The UNT Digital Library
Hanford Tank 241-C-106: Residual Waste Contaminant Release Model and Supporting Data (open access)

Hanford Tank 241-C-106: Residual Waste Contaminant Release Model and Supporting Data

This report was revised in May 2007 to correct values in Section 3.4.1.7, second paragraph, last sentence; 90Sr values in Tables 3.22 and 3.32; and 99Tc values Table 4.3 and in Chapter 5. In addition, the tables in Appendix F were updated to reflect corrections to the 90Sr values. The rest of the text remains unchanged from the original report issued in May 2005. CH2M HILL is producing risk/performance assessments to support the closure of single-shell tanks at the DOE's Hanford Site. As part of this effort, staff at PNNL were asked to develop release models for contam¬inants of concern that are present in residual sludge remaining in tank 241-C-106 (C-106) after final retrieval of waste from the tank. This report provides the information developed by PNNL.
Date: May 23, 2007
Creator: Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F. & Schaef, Herbert T.
Object Type: Report
System: The UNT Digital Library
Hanford Tanks 241-C-203 and 241 C 204: Residual Waste Contaminant Release Model and Supporting Data (open access)

Hanford Tanks 241-C-203 and 241 C 204: Residual Waste Contaminant Release Model and Supporting Data

This report was revised in May 2007 to correct 90Sr values in Chapter 3. The changes were made on page 3.9, paragraph two and Table 3.10; page 3.16, last paragraph on the page; and Tables 3.21 and 3.31. The rest of the text remains unchanged from the original report issued in October 2004. This report describes the development of release models for key contaminants that are present in residual sludge remaining after closure of Hanford Tanks 241-C-203 (C-203) and 241-C-204 (C-204). The release models were developed from data generated by laboratory characterization and testing of samples from these two tanks. Key results from this work are (1) future releases from the tanks of the primary contaminants of concern (99Tc and 238U) can be represented by relatively simple solubility relationships between infiltrating water and solid phases containing the contaminants; and (2) high percentages of technetium-99 in the sludges (20 wt% in C-203 and 75 wt% in C-204) are not readily water leachable, and, in fact, are very recalcitrant. This is similar to results found in related studies of sludges from Tank AY-102. These release models are being developed to support the tank closure risk assessments performed by CH2M HILL Hanford Group, …
Date: May 23, 2007
Creator: Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F. & Schaef, Herbert T.
Object Type: Report
System: The UNT Digital Library
Retention and Switching Kinetics of Protonated Gate Field Effect Transistors (open access)

Retention and Switching Kinetics of Protonated Gate Field Effect Transistors

The switching and memory retention time has been measured in 50 {micro}m gatelength pseudo-non-volatile memory MOSFETS containing, protonated 40 nm gate oxides. Times of the order of 3.3 seconds are observed for fields of 3 MV cm{sup {minus}1}. The retention time with protons placed either at the gate oxide/substrate or gate oxide/gate electrode interfaces is found to better than 96{percent} after 5,000 seconds. Measurement of the time dependence of the source-drain current during switching provides clear evidence for the presence of dispersive proton transport through the gate oxide.
Date: May 23, 2000
Creator: Devine, R. A. B. & Herrera, Gilbert V.
Object Type: Article
System: The UNT Digital Library
BACKSCATTER GUAGE DESCRIPTION FOR INSPECTION OF NEUTRON ABSORBER AND UNIFORMITY (open access)

BACKSCATTER GUAGE DESCRIPTION FOR INSPECTION OF NEUTRON ABSORBER AND UNIFORMITY

This paper describes design, calibration, and testing of a dual He-3 detector neutron backscatter gauge for use in the Savannah River Site Mixed Oxide Fuel project. The gauge is demonstrated to measure boron content and uniformity in concrete slabs used in the facility construction.
Date: May 23, 2012
Creator: Dewberry, R.; Gibbs, K. & Couture, A.
Object Type: Article
System: The UNT Digital Library
Molecular Weight Distributions of Irradiated Siloxane-Based Elastomers: A Complementary Study by Statistical Modeling and Multiple Quantum Nuclear Magnetic Resonance. (open access)

Molecular Weight Distributions of Irradiated Siloxane-Based Elastomers: A Complementary Study by Statistical Modeling and Multiple Quantum Nuclear Magnetic Resonance.

None
Date: May 23, 2010
Creator: Dinh, L N; Mayer, B P; Maiti, A; Chinn, S C & Maxwell, R S
Object Type: Article
System: The UNT Digital Library
Estimation of Steady-State and Transcient Power Distributions for the RELAP Analyses of the 1963 Loss-Of-Flow and Loss-Of-Pressure Tests at br2. (open access)

Estimation of Steady-State and Transcient Power Distributions for the RELAP Analyses of the 1963 Loss-Of-Flow and Loss-Of-Pressure Tests at br2.

To support the safety analyses required for the conversion of the Belgian Reactor 2 (BR2) from highly-enriched uranium (HEU) to low-enriched uranium (LEU) fuel, the simulation of a number of loss-of-flow tests, with or without loss of pressure, has been undertaken. These tests were performed at BR2 in 1963 and used instrumented fuel assemblies (FAs) with thermocouples (TC) imbedded in the cladding as well as probes to measure the FAs power on the basis of their coolant temperature rise. The availability of experimental data for these tests offers an opportunity to better establish the credibility of the RELAP5-3D model and methodology used in the conversion analysis. In order to support the HEU to LEU conversion safety analyses of the BR2 reactor, RELAP simulations of a number of loss-of-flow/loss-of-pressure tests have been undertaken. Preliminary analyses showed that the conservative power distributions used historically in the BR2 RELAP model resulted in a significant overestimation of the peak cladding temperature during the transient. Therefore, it was concluded that better estimates of the steady-state and decay power distributions were needed to accurately predict the cladding temperatures measured during the tests and establish the credibility of the RELAP model and methodology. The new approach ('best …
Date: May 23, 2011
Creator: Dionne, B. & Tzanos, C. P. (Nuclear Engineering Division)
Object Type: Report
System: The UNT Digital Library
Thermal properties for the thermal-hydraulics analyses of the BR2 maximum nominal heat flux. (open access)

Thermal properties for the thermal-hydraulics analyses of the BR2 maximum nominal heat flux.

This memo describes the assumptions and references used in determining the thermal properties for the various materials used in the BR2 HEU (93% enriched in {sup 235}U) to LEU (19.75% enriched in {sup 235}U) conversion feasibility analysis. More specifically, this memo focuses on the materials contained within the pressure vessel (PV), i.e., the materials that are most relevant to the study of impact of the change of fuel from HEU to LEU. This section is regrouping all of the thermal property tables. Section 2 provides a summary of the thermal properties in form of tables while the following sections present the justification of these values. Section 3 presents a brief background on the approach used to evaluate the thermal properties of the dispersion fuel meat and specific heat capacity. Sections 4 to 7 discuss the material properties for the following materials: (i) aluminum, (ii) dispersion fuel meat (UAlx-Al and U-7Mo-Al), (iii) beryllium, and (iv) stainless steel. Section 8 discusses the impact of irradiation on material properties. Section 9 summarizes the material properties for typical operating temperatures. Appendix A elaborates on how to calculate dispersed phase's volume fraction. Appendix B shows the evolution of the BR2 maximum heat flux with burnup.
Date: May 23, 2011
Creator: Dionne, B.; Kim, Y. S. & Hofman, G. L. (Nuclear Engineering Division)
Object Type: Report
System: The UNT Digital Library
A review of the Model 5A uranium hexafluoride cylinder (open access)

A review of the Model 5A uranium hexafluoride cylinder

Both the Model 5A (Monel 400) and 5A (Monel 400) Modified five-inch cylinders have been used at the Portsmouth GDP to withdraw, store, and ship highly enriched uranium hexafluoride. As a result of a generic cracking problem with Monel 400 valve-boss material, a cylinder modification was implemented in the mid 1970s. This modification resulted in the violation of the ASME ''Code'' stamp status of the Model 5A Modified cylinder. Hydrostatic testing-to- rupture data indicated that the Model 5A Modified cylinders had ruptured strengths equivalent to that of the original Model 5A cylinders. An independent consultant reviewed the available information and confirmed that the Model 5A Modified cylinders ''will with proper maintenance continue to perform satisfactorily for many additional years of service.'' Based on the test data and consultant's review, DOE approved continued use of the 5A Modified cylinder and also requested procurement of replacement 5B cylinders be expedited. Currently, the 5A modified cylinders are in the production, storage, shipment cycle, and a sufficient number of 5B cylinders has been ordered to accommodate the projected product shipping requirements for the Navy flow. 3 tabs.
Date: May 23, 1989
Creator: Dorning, R.E. II
Object Type: Report
System: The UNT Digital Library
Wind Powering America: America's Wind Power...A Natural Resource (open access)

Wind Powering America: America's Wind Power...A Natural Resource

The Wind Powering America Initiative is a regionally-based effort to increase the use of clean wind energy in the United States over the next two decades. The purpose of this brochure is to provide a brief description of the initiative, its goals, benefits, and strategy as well as a list of contacts for those interested in obtaining more information.
Date: May 23, 2001
Creator: Dougherty, P.
Object Type: Book
System: The UNT Digital Library
Fiber-Matrix Interface Studies on Electron Beam Cured Composites (open access)

Fiber-Matrix Interface Studies on Electron Beam Cured Composites

The recently completed Department of Energy (DOE) and industry sponsored Cooperative Research and Development Agreement (CRADA) entitled, ''Electron Beam Curing of Polymer Matrix Composites,'' determined that the interlaminar shear strength properties of the best electron beam cured IM7/epoxy composites were 19-28% lower than autoclave cured IM7/epoxy composites (i.e. IM7/977-2 and IM7/977-3). Low interlaminar shear strength is widely acknowledged as the key barrier to the successful acceptance and implementation of electron beam cured composites in the aircraft/aerospace industry. The objective of this work was to improve the interlaminar shear strength properties of electron beam cured composites by formulating and evaluating several different fiber sizings or coating materials. The researchers have recently achieved some promising results by having discovered that the application of epoxy-based, electron beam compatible sizings or coatings onto surface-treated, unsized IM7 carbon fibers improved the composite interlaminar shear strength properties by as much as 55% versus composites fabricated from surface-treated, unsized IM7 fibers. In addition, by applying these same epoxy-based sizings or coatings onto surface-treated, unsized IM7 fibers it was possible to achieve an 11% increase in the composite interlaminar shear strength compared to composites made from surface-treated, GP-sized IM7 fibers. Work is continuing in this area of research …
Date: May 23, 1999
Creator: Drazel, L. T.; Janke, C. J. & Yarborough, K. D.
Object Type: Article
System: The UNT Digital Library
RATIO OF U-232 TO U-233 PRODUCED IN THE TBR (open access)

RATIO OF U-232 TO U-233 PRODUCED IN THE TBR

The production of U/sup 232/ in the cost optimized TBR and oneregion thorlum oxide-uranium oxide slurry reactor has been estimated to be, respectively, 40 and 260 parts per million parts of U/sup 233/ produced. These production rates are compared with corresponding production rates in irradiated thorium rods and found to be comparable. Recommendations are made for increasing the purity of the U/sup 233/ product. (auth)
Date: May 23, 1955
Creator: Dresner, L
Object Type: Report
System: The UNT Digital Library
Introduction to Python (open access)

Introduction to Python

This report contains viewgraphs on a object-oriented programming language called Python. The basic elements of Python and its new numerical extension are discussed.
Date: May 23, 1996
Creator: Dubois, P.F.
Object Type: Article
System: The UNT Digital Library
EFFECT OF SURFACE PREPARATION TECHNIQUE ON THE RADIATION DETECTOR PERFORMANCEOF CDZNTE (open access)

EFFECT OF SURFACE PREPARATION TECHNIQUE ON THE RADIATION DETECTOR PERFORMANCEOF CDZNTE

Synthetic CdZnTe (CZT) semiconducting crystals are highly suitable for the room temperature-based detection of gamma radiation. The surface preparation of Au contacts on surfaces of CZT detectors is typically conducted after (1) polishing to remove artifacts from crystal sectioning and (2) chemical etching, which removes residual mechanical surface damage however etching results in a Te rich surface layer that is prone to oxidize. Our studies show that CZT surfaces that are only polished (as opposed to polished and etched) can be contacted with Au and will yield lower surface currents. Due to their decreased dark currents, these as-polished surfaces can be used in the fabrication of gamma detectors exhibiting a higher performance than polished and etched surfaces with relatively less peak tailing and greater energy resolution. CdZnTe or ''CZT'' crystals are attractive to use in homeland security applications because they detect radiation at room temperature and do not require low temperature cooling as with silicon- and germanium-based detectors. Relative to germanium and silicon detectors, CZT is composed of higher Z elements and has a higher density, which gives it greater ''stopping power'' for gamma rays making a more efficient detector. Single crystal CZT materials with high bulk resistivity ({rho}>10{sup 10} …
Date: May 23, 2007
Creator: Duff, M
Object Type: Article
System: The UNT Digital Library
Characterization of Fish Passage Conditions through a Francis Turbine and Regulating Outlet at Cougar Dam, Oregon, Using Sensor Fish, 2009–2010 (open access)

Characterization of Fish Passage Conditions through a Francis Turbine and Regulating Outlet at Cougar Dam, Oregon, Using Sensor Fish, 2009–2010

Fish passage conditions through a Francis turbine and a regulating outlet (RO) at Cougar Dam on the south fork of the McKenzie River in Oregon were evaluated by Pacific Northwest National Laboratory for the U.S. Army Corps of Engineers, Portland District, using Sensor Fish devices. The objective of the study was to describe and compare passage exposure conditions, identifying potential fish injury regions encountered during passage via specific routes. The RO investigation was performed in December 2009 and the turbine evaluation in January 2010, concurrent with HI-Z balloon-tag studies by Normandeau Associates, Inc. Sensor Fish data were analyzed to estimate 1) exposure conditions, particularly exposure to severe collision, strike, and shear events by passage route sub-regions; 2) differences in passage conditions between passage routes; and 3) relationships to live-fish injury and mortality data estimates. Comparison of the three passage routes evaluated at Cougar Dam indicates that the RO passage route through the 3.7-ft gate opening was relatively the safest route for fish passage under the operating conditions tested; turbine passage was the most deleterious. These observations were supported also by the survival and malady estimates obtained from live-fish testing. Injury rates were highest for turbine passage. Compared to mainstem Columbia …
Date: May 23, 2011
Creator: Duncan, Joanne P.
Object Type: Report
System: The UNT Digital Library