Observation of Self-Sputtering in Energetic Condensation of Metal Ions (open access)

Observation of Self-Sputtering in Energetic Condensation of Metal Ions

The condensation of energetic metal ions on a surface may cause self-sputtering even in the absence of substrate bias. Charge-state-averaged self-sputtering yields were determined for both zirconium and gold ions generated by a cathodic vacuum arc. Films were deposited on differently biased substrates exposed to streaming Zr and Au vacuum arc plasma. The self-sputtering yields for both metals were estimated to be about 0.05 in the absence of bias, and exceeding 0.5 when bias reached-50 V. These surprisingly high values can be reconciled with binary collision theory and molecular dynamics calculations taking high the kinetic and potential energy of vacuum arc ions into account.
Date: June 16, 2004
Creator: Anders, Andre
Object Type: Article
System: The UNT Digital Library
The Littlest Higgs Model and One-Loop Electroweak Precision Constraints. (open access)

The Littlest Higgs Model and One-Loop Electroweak Precision Constraints.

We present in this talk the one-loop electroweak precision constraints in the Littlest Higgs model, including the logarithmically enhanced contributions from both fermion and scalar loops. We find the one-loop contributions are comparable to the tree level corrections in some regions of parameter space. A low cutoff scale is allowed for a non-zero triplet VEV. Constraints on various other parameters in the model are also discussed. The role of triplet scalars in constructing a consistent renormalization scheme is emphasized.
Date: June 16, 2004
Creator: Chen, M. C. & Dawson, S.
Object Type: Article
System: The UNT Digital Library
Sudan: The Crisis in Darfur (open access)

Sudan: The Crisis in Darfur

This report discusses the crisis in Darfur, which began in February 2003, when two rebel groups emerged to challenge the National Islamic Front (NIF) government in DarfurThe report describes the mechanisms used to cleanse the area of non-Arabs by “total disengagement of administration and suspension of all government services.”
Date: June 16, 2004
Creator: Dagne, Ted
Object Type: Report
System: The UNT Digital Library
Local structure around Sn in CeCoIn{sub 5-x}Sn{sub x} (open access)

Local structure around Sn in CeCoIn{sub 5-x}Sn{sub x}

The local structure around Sn dopants in CeCoIn{sub 5-x}Sn{sub z} has been probed by extended x-ray absorption fine structure (EXAFS) technique. The fit results for both x = 0.12 and x = 0.18 clearly indicate the dopant Sn atoms predominantly occupying the planar In(1) site. These results are consistent with the quasi-two-dimensional electronic properties of CeCoIn{sub 5} and is discussed in relation to the observed bulk properties.
Date: June 16, 2004
Creator: Daniel, M.; Han, S.-W.; Booth, C.H.; Cornelius, A.L.; Bauer, E.D. & Sarrao, J.L.
Object Type: Article
System: The UNT Digital Library
Systems Analysis of Safeguards Effectiveness in a Uranium Conversion Facility (open access)

Systems Analysis of Safeguards Effectiveness in a Uranium Conversion Facility

The U.S. Department of Energy (DOE) is interested in developing tools and methods for potential U.S. use in designing and evaluating safeguards systems. For this goal several DOE National Laboratories are defining the characteristics of typical facilities of several size scales, and the safeguards measures and instrumentation that could be applied. Lawrence Livermore National Laboratory is providing systems modeling and analysis of facility and safeguards operations, diversion path generation, and safeguards system effectiveness. The constituent elements of diversion scenarios are structured using directed graphs (digraphs) and fault trees. Safeguards indicator probabilities are based on sampling statistics and/or measurement accuracies. Scenarios are ranked based on value and quantity of material removed and the estimated probability of non-detection. Significant scenarios, especially those involving timeliness or randomly varying order of events, are transferred to simulation analysis. Simulations show the range of conditions encountered by the safeguards measurements and inspections, e.g., the quantities of intermediate materials in temporary storage and the time sequencing of material flow. Given a diversion campaign, simulations show how much the range of the same parameters observed by the safeguards system can differ from the base-case range. The combination of digraphs, fault trees, statistics and simulation constitute a method for …
Date: June 16, 2004
Creator: Elayat, H A; Lambert, H & O'Connell, W J
Object Type: Article
System: The UNT Digital Library
Resolution of the Long-Standing Overprediction of the Resonance to Intercombination Line-Intensity Ratio in mid-Z Neonlike Ions (open access)

Resolution of the Long-Standing Overprediction of the Resonance to Intercombination Line-Intensity Ratio in mid-Z Neonlike Ions

The Ne-like resonance 2p{sup 6} {sup 1}S-2p{sup 5}3d{sup 1}P(3C) to intercombination 2p{sup 6} {sup 1}S-2p{sup 5}3d{sup 1}D(3D) line-intensity ratio R(3C/3D) has been extensively studied through high-accuracy measurements and calculations of atomic structure and collision cross sections. However, even state-of-the-art relativistic multiconfiguration atomic-physics codes generally predict values of R(3C/3D) that are significantly larger than those observed in coronal-density experiments. In this paper, predictions of R(3C/3D) across the Ne-like isoelectronic sequence from chromium to silver are brought into agreement with coronal-density experimental measurements in two steps: first by including a semi-empirical correction in the collisional atomic data due to configuration-interaction effects, and next by including the effects of cascades on the upper level populations. The configuration-interaction correction is inspired by the observation that nearly all data-production codes fail to predict R(3C/3D) correctly and is justified theoretically by a careful analysis of configuration-interaction contributions to level energies. The dependence of R(3C/3D) with electron density and its agreement with moderate-density measurements are shown. A brief description of the application of our technique to line ratios in He- and Ni-like x-ray spectra is also given.
Date: June 16, 2004
Creator: Fournier, K B & Hansen, S B
Object Type: Article
System: The UNT Digital Library
U.N. Convention Against Torture (CAT): Overview and Application to Interrogation Techniques (open access)

U.N. Convention Against Torture (CAT): Overview and Application to Interrogation Techniques

None
Date: June 16, 2004
Creator: Garcia, Michael John
Object Type: Report
System: The UNT Digital Library
Status of The General Atomics Low Speed Urban Maglev Technology Development Program (open access)

Status of The General Atomics Low Speed Urban Maglev Technology Development Program

This paper presents the status of General Atomics Urban Maglev Program. The development provides an innovative approach for low speed transportation suitable for very challenging urban environments. Permanent magnets arranged in a 'Halbach' array configuration produce a relatively stiff magnetic suspension operating with an air gap of 25 mm. The project has progressed from design and prototype hardware testing, to the construction of a 120-meter full-scale test track, located in San Diego, California. Dynamic testing of the levitation, propulsion and guidance systems is being performed.
Date: June 16, 2004
Creator: Gurol, S; Baldi, R; Bever, D & Post, R
Object Type: Article
System: The UNT Digital Library
Agricultural Export and Food Aid Programs (open access)

Agricultural Export and Food Aid Programs

This report discusses projected agricultural imports and exports for FY2004, as well as legislation that deals with federal programs in support of agricultural exports and federal aid dedicated to farms and agricultural reform.
Date: June 16, 2004
Creator: Hanrahan, Charles E.
Object Type: Report
System: The UNT Digital Library
Electron-helium scattering in the S-wave model using exterior complex scaling (open access)

Electron-helium scattering in the S-wave model using exterior complex scaling

Electron-impact excitation and ionization of helium is studied in the S-wave model. The problem is treated in full dimensionality using a time-dependent formulation of the exterior complex scaling method that does not involve the solution of large linear systems of equations. We discuss the steps that must be taken to compute stable ionization amplitudes. We present total excitation, total ionization and single differential cross sections from the ground and n=2 excited states and compare our results with those obtained by others using a frozen-core model.
Date: June 16, 2004
Creator: Horner, Daniel A.; McCurdy, C. William & Rescigno, Thomas N.
Object Type: Article
System: The UNT Digital Library
Coupled Geochemical and Hydrological Processes Governing the Fate and Transport of Radionuclides and Toxic Metals Beneath the Hanford Tank Farms (open access)

Coupled Geochemical and Hydrological Processes Governing the Fate and Transport of Radionuclides and Toxic Metals Beneath the Hanford Tank Farms

This annual report describes 1.5 y of progress on a 3 y project. The project addresses the goals of the Environmental Management Sciences Program (EMSP) that seeks innovative basic research to benefit cleanup technologies and decision-making strategies for contaminated environments. Our project specifically addresses Hanford research needs in subsurface science by contributing to the objectives of the Tank Farm Vadose Characterization Project and the 200 Area Remedial Action Project which are components of the Hanford Site Groundwater/Vadose Zone Integration Project (Integration Project). The work described within is intended to advance the technological and scientific needs associated with the long-term management of the enormous in-ground inventories of 235/238U, 99Tc, 60Co, and Cr(VI) present at the Hanford site. We believe that scientifically defensible predictions of contaminant transport and strategies for remediation must be based upon a field-relevant understanding of coupled hydrological and geochemical processes that control subsurface contaminant fate and transport. This research project investigates the migration of 235/238U, 90Sr, 60Co, and Cr(VI) in undisturbed sediments from the Hanford site using realistic experimental protocols designed to delineate complex hydrological and geochemical processes controlling contaminant movement.
Date: June 16, 2004
Creator: Jardin, Philip M.; Fendorf, Scott E. & Mayes, Melanie
Object Type: Report
System: The UNT Digital Library
Nylon Dissolution in Nitric Acid Solutions (open access)

Nylon Dissolution in Nitric Acid Solutions

H Area Operations is planning to process Pu-contaminated uranium scrap in support of de-inventory efforts. Nylon bags will be used to hold materials to be dissolved in H-Canyon. Based on this set of twelve nylon dissolutions, it is concluded that (when other variables are held constant): increased acid concentration results in increased dissolution rates; increased acid concentration results in a lower dissolution onset temperature; little, if any, H plus is consumed during the depolymerization process; and 2.0-3.0 M HNO3, with 0.025 M KF and 2 g/L B, is satisfactory for the dissolution of nylon bag materials to be used during H-Canyon processing.
Date: June 16, 2004
Creator: KESSINGER, GLENF.
Object Type: Report
System: The UNT Digital Library
Fs Laser Fabrication of Photonic Structures in Glass: the Role of Glass Composition (open access)

Fs Laser Fabrication of Photonic Structures in Glass: the Role of Glass Composition

The use of fs lasers to directly write photonic structures inside a glass has great potential as a fabrication method for three-dimensional all-optical integrated components. The ability to use this technique with different glass compositions--specifically tailored for a specific photonics application--is critical to its successful exploitation. Consequently, it is important to understand how glass composition effects waveguide fabrication with fs laser pulses and how different glasses are structurally modified after exposure to fs laser pulses. We have used confocal laser spectroscopy to monitor the changes in glass structure that are associated with waveguide fabrication. Using a low power continuous wave (cw) Ar laser as excitation source we have measured both Raman and fluorescence spectra of the modified regions. Raman spectroscopy provides us with information on the network structure, whereas fluorescence measurements reveal the presence of optically active point defects in the glass. In this paper we review our work on fs-laser fabrication and characterization of photonic structures in glass and discuss the effect of glass composition on processing parameters and structural modification.
Date: June 16, 2004
Creator: Krol, D M; Chan, J W; Huser, T R; Risbud, S H & Hayden, J S
Object Type: Article
System: The UNT Digital Library
Experimental Evaluation of a Negative Ion Source for a Heavy Ion Fusion Negative Ion Driver (open access)

Experimental Evaluation of a Negative Ion Source for a Heavy Ion Fusion Negative Ion Driver

Negative halogen ions have recently been proposed as a possible alternative to positive ions for heavy ion fusion drivers because electron accumulation would not be a problem in the accelerator, and if desired, the beams could be photo-detached to neutrals. To test the ability to make suitable quality beams, an experiment was conducted at Lawrence Berkeley National Laboratory using chlorine in an RF-driven ion source. Without introducing any cesium (which is required to enhance negative ion production in hydrogen ion sources) a negative chlorine current density of 45 mA/cm{sup 2} was obtained under the same conditions that gave 57 45 mA/cm{sup 2} of positive chlorine, suggesting the presence of nearly as many negative ions as positive ions in the plasma near the extraction plane. The negative ion spectrum was 99.5% atomic chlorine ions, with only 0.5% molecular chlorine, and essentially no impurities. Although this experiment did not incorporate the type of electron suppression technology that i s used in negative hydrogen beam extraction, the ratio of co-extracted electrons to Cl{sup -} was as low as 7 to 1, many times lower than the ratio of their mobilities, suggesting that few electrons are present in the near-extractor plasma. This, along with …
Date: June 16, 2004
Creator: L.R. Grisham, S.K. Hahto, S.T. Hahto, J.W. Kwan, and K.N. Leung
Object Type: Report
System: The UNT Digital Library
High-Frequency Electromagnetic Impedance Measurements for Characterization, Monitoring and Verification Efforts (open access)

High-Frequency Electromagnetic Impedance Measurements for Characterization, Monitoring and Verification Efforts

Non-invasive, high-resolution imaging of the shallow subsurface is needed for delineation of buried waste, detection of unexploded ordinance, verification and monitoring of containment structures, and other environmental applications. Electromagnetic (EM) measurements at frequencies between 0.1 and 100 MHz are important for such applications, because the induction number of many targets is small and the ability to determine the dielectric permittivity in addition to electrical conductivity of the subsurface is possible. Earlier workers were successful in developing systems for detecting anomalous areas, but no quantifiable information was accurately determined. For high-resolution imaging, accurate measurements are necessary so the field data can be mapped into the space of the subsurface parameters. We are developing a non-invasive method for accurately mapping the electrical conductivity and dielectric permittivity of the shallow subsurface using the EM impedance approach (Frangos, 2001; Lee and Becker, 2001; Song et al., 2002, Tseng et al., 2003). Electric and magnetic sensors are being tested and calibrated on sea water and in a known area against theoretical predictions, thereby insuring that the data collected with the high-frequency impedance (HFI) system will support high-resolution, multi-dimensional imaging techniques.
Date: June 16, 2004
Creator: Lee, Ki Ha; Becker, Alex & Tseng, Hung-Wen
Object Type: Report
System: The UNT Digital Library
Solution Verification Linked to Model Validation, Reliability, and Confidence (open access)

Solution Verification Linked to Model Validation, Reliability, and Confidence

The concepts of Verification and Validation (V&V) can be oversimplified in a succinct manner by saying that 'verification is doing things right' and 'validation is doing the right thing'. In the world of the Finite Element Method (FEM) and computational analysis, it is sometimes said that 'verification means solving the equations right' and 'validation means solving the right equations'. In other words, if one intends to give an answer to the equation '2+2=', then one must run the resulting code to assure that the answer '4' results. However, if the nature of the physics or engineering problem being addressed with this code is multiplicative rather than additive, then even though Verification may succeed (2+2=4 etc), Validation may fail because the equations coded are not those needed to address the real world (multiplicative) problem. We have previously provided a 4-step 'ABCD' quantitative implementation for a quantitative V&V process: (A) Plan the analyses and validation testing that may be needed along the way. Assure that the code[s] chosen have sufficient documentation of software quality and Code Verification (i.e., does 2+2=4?). Perform some calibration analyses and calibration based sensitivity studies (these are not validated sensitivities but are useful for planning purposes). Outline the …
Date: June 16, 2004
Creator: Logan, R W & Nitta, C K
Object Type: Report
System: The UNT Digital Library
Core Plasma Charge States of Mo Ions in High Electron Temperature JET and FTU Plasmas (open access)

Core Plasma Charge States of Mo Ions in High Electron Temperature JET and FTU Plasmas

None
Date: June 16, 2004
Creator: Mattioli, M; Carraro, L; Bortolon, A; Coffey, I; Finkenthal, M; Fournier, K et al.
Object Type: Article
System: The UNT Digital Library
9-11 Commission Hearing #12, June 16, 2004, Part 1 captions transcript

9-11 Commission Hearing #12, June 16, 2004, Part 1

Recording of the twelfth public hearing held by the National Commission on Terrorist Attacks upon the United States on June 16, 2004 at the NTSB Conference Center in Washington, D.C. The two-day hearing focused on two distinct topics: the 9-11 Plot and the federal government's immediate response to the attacks on September 11, 2001. This section includes the staff statement entitled overview of the enemy in addition to the first panel on Al-Qaeda with testimony from Mary Deborah Doran and Patrick J. Fitzgerald.
Date: June 16, 2004
Creator: National Commission on Terrorist Attacks upon the United States
Object Type: Video
System: The UNT Digital Library
9-11 Commission Hearing #12, June 16, 2004, Part 2 captions transcript

9-11 Commission Hearing #12, June 16, 2004, Part 2

Recording of the twelfth public hearing held by the National Commission on Terrorist Attacks upon the United States on June 16, 2004 at the NTSB Conference Center in Washington, D.C. The two-day hearing focused on two distinct topics: the 9-11 Plot and the federal government's immediate response to the attacks on September 11, 2001. This section includes the staff statement entitled outline of the 9/11 plot, in addition to the second panel on the outline of the outline of the 9/11 plot with testimony from Jacqueline Maguire, James N. Fitzgerald, and Adam B. Drucker.
Date: June 16, 2004
Creator: National Commission on Terrorist Attacks upon the United States
Object Type: Video
System: The UNT Digital Library
Staff Statement: Outline of the 9/11 Plot (open access)

Staff Statement: Outline of the 9/11 Plot

Official statement issued by the National Commission on Terrorist Attacks upon the United States describing preliminary findings regarding the conspiracy that produced the September 11 terrorist attacks against the United States.
Date: June 16, 2004
Creator: National Commission on Terrorist Attacks upon the United States
Object Type: Text
System: The UNT Digital Library
Staff Statement: Overview of the Enemy (open access)

Staff Statement: Overview of the Enemy

Official statement issued by the National Commission on Terrorist Attacks upon the United States describing preliminary findings regarding the nature of the enemy that carried out the September 11 attacks.
Date: June 16, 2004
Creator: National Commission on Terrorist Attacks upon the United States
Object Type: Text
System: The UNT Digital Library
Transcript of 9-11 Commission Hearing 12, June 16, 2004 (open access)

Transcript of 9-11 Commission Hearing 12, June 16, 2004

Transcript of the twelfth public hearing held by the National Commission on Terrorist Attacks upon the United States held June 16, 2004 at the NTSB Conference Center in Washington, D.C. The two-day hearing focused on two distinct topics: the 9-11 Plot and the federal government's immediate response to the attacks on September 11, 2001.On June 16 at the National Transportation Safety Board Conference Center, the Commission heard from several of the federal government's top law enforcement and intelligence experts on al Qaeda and the 9-11 plot. The hearing resumed on June 17, with the top military and civilian aviation officials testifying about their agencies' responses to the 9-11 attacks. In addition to witness testimony, three staff statements were presented during the course of the proceedings.
Date: June 16, 2004
Creator: National Commission on Terrorist Attacks upon the United States
Object Type: Text
System: The UNT Digital Library
Radiographic Spectroscopy of Atomic Composition of Materials: a Multi-Energy Approach (open access)

Radiographic Spectroscopy of Atomic Composition of Materials: a Multi-Energy Approach

A theoretical model of multi-energy radiography (MER) for reconstruction of the atomic structure is proposed. It is shown that, using multi-channel absorption and detection of radiation, effective atomic number and quantitative chemical composition of the materials can be readily reconstructed. This approach opens prospects for improvement of efficiency of X-ray techniques in non-destructive testing, nuclear and safety monitoring, security customs control, and others.
Date: June 16, 2004
Creator: Naydenov, S V; Ryzhikov, V D & Smith, C F
Object Type: Article
System: The UNT Digital Library
New advances in three dimensional transient electromagnetic inversion (open access)

New advances in three dimensional transient electromagnetic inversion

Inversion of transient electromagnetic (TEM) data sets to image the subsurface three-dimensional (3-D) electrical conductivity and magnetic permeability properties can be done directly in the time domain. The technique, first introduced by Wang et al. (1994) for causal and diffusive electromagnetic fields and subsequently implemented by Zhdanov and Portniaguine (1997) in the framework of iterative migration, is based upon imaging methods originally developed for seismic wavefields (Claerbout, 1971; Tarantola, 1984). In this paper we advance the original derivations of Wang et al. (1994) and Zhdanov and Portniaguine (1997) to treat non-causal TEM fields, as well as correct a flaw in the theory for treatment of magnetic field data. Our 3D imaging scheme is based on a conjugate-gradient search for the minimum of an error functional involving EM measurements governed by Maxwell's equations without displacement currents. Treatment for magnetic field, voltage (time derivative of the magnetic field) and electric field data are given. The functional can be computed by propagating the data errors back into the model in reverse time along with a DC field, sourced by the integrated data errors over the measurement time range. By correlating these fields, including the time-integrated back-propagated fields, with the corresponding incident field and …
Date: June 16, 2004
Creator: Newman, Gregory A. & Commer, Michael
Object Type: Article
System: The UNT Digital Library