Referee's report on Blast-wave diagnosis of self-focusing of an intense laser pulse in a cluster medium, by Symes et al. (open access)

Referee's report on Blast-wave diagnosis of self-focusing of an intense laser pulse in a cluster medium, by Symes et al.

None
Date: November 28, 2006
Creator: Edwards, M J
Object Type: Report
System: The UNT Digital Library
California Levee Risk, Now and in the Future:Identifying Research and Tool Development Needs (open access)

California Levee Risk, Now and in the Future:Identifying Research and Tool Development Needs

The Center for Catastrophic Risk Management (CCRM) and the California Center for Environmental Law and Policy (CCELP) at UC Berkeley and the Lawrence Livermore National Laboratory (LLNL) joined together to cosponsor a workshop to define research requirements to mitigate the hazards facing the Sacramento-San Joaquin Delta Levee system. The Workshop was intended to provide a forum to (1) Report assessments of current vulnerabilities facing the levees, such as structural failure, seismic loading, flooding, terrorism; (2) Consider longer term challenges such as climate change, sea level rise; and (3) Define research requirements to fill gaps in knowledge and reduce uncertainties in hazard assessments.
Date: November 28, 2006
Creator: Newmark, Robin L.; Hanemann, Michael & Farber, Daniel
Object Type: Report
System: The UNT Digital Library
HYDROGEN ELECTROLYZER FLOW DISTRIBUTOR MODEL (open access)

HYDROGEN ELECTROLYZER FLOW DISTRIBUTOR MODEL

The hybrid sulfur process (HyS) hydrogen electrolyzer consists of a proton exchange membrane (PEM) sandwiched between two porous graphite layers. An aqueous solution of sulfuric acid with dissolved SO{sub 2} gas flows parallel to the PEM through the porous graphite layer on the anode side of the electrolyzer. A flow distributor, consisting of a number of parallel channels acting as headers, promotes uniform flow of the anolyte fluid through the porous graphite layer. A numerical model of the hydraulic behavior of the flow distributor is herein described. This model was developed to be a tool to aid the design of flow distributors. The primary design objective is to minimize spatial variations in the flow through the porous graphite layer. The hydraulic data from electrolyzer tests consists of overall flowrate and pressure drop. Internal pressure and flow distributions are not measured, but these details are provided by the model. The model has been benchmarked against data from tests of the current electrolyzer. The model reasonably predicts the viscosity effect of changing the fluid from water to an aqueous solution of 30 % sulfuric acid. The permeability of the graphite layer was the independent variable used to fit the model to the …
Date: September 28, 2006
Creator: Shadday, M
Object Type: Report
System: The UNT Digital Library
Characterization of Hydrogen Complex Formation in III-V Semiconductors (open access)

Characterization of Hydrogen Complex Formation in III-V Semiconductors

Atomic hydrogen has been found to react with some impurity species in semiconductors. Hydrogenation is a methodology for the introduction of atomic hydrogen into the semiconductor for the express purpose of forming complexes within the material. Efforts to develop hydrogenation as an isolation technique for AlGaAs and Si based devices failed to demonstrate its commercial viability. This was due in large measure to the low activation energies of the formed complexes. Recent studies of dopant passivation in long wavelength (0.98 - 1.55m) materials suggested that for the appropriate choice of dopants much higher activation energies can be obtained. This effort studied the formation of these complexes in InP, This material is extensively used in optoelectronics, i.e., lasers, modulators and detectors. The experimental techniques were general to the extent that the results can be applied to other areas such as sensor technology, photovoltaics and to other material systems. The activation energies for the complexes have been determined and are reported in the scientific literature. The hydrogenation process has been shown by us to have a profound effect on the electronic structure of the materials and was thoroughly investigated. The information obtained will be useful in assessing the long term reliability of …
Date: September 28, 2006
Creator: Williams, Michael D.
Object Type: Report
System: The UNT Digital Library
Mechanically Cooled Large-Volume Germanium Detector Systems for Nuclear Explosion Monitoring (open access)

Mechanically Cooled Large-Volume Germanium Detector Systems for Nuclear Explosion Monitoring

None
Date: July 28, 2006
Creator: Hull, E.L.
Object Type: Text
System: The UNT Digital Library
Vibration Stabilization of a Mechanical Model of a X-Band Linear Collider Final Focus Magnet (open access)

Vibration Stabilization of a Mechanical Model of a X-Band Linear Collider Final Focus Magnet

The small beam sizes at the interaction point of a X-band linear collider require mechanical stabilization of the final focus magnets at the nanometer level. While passive systems provide adequate performance at many potential sites, active mechanical stabilization is useful if the natural or cultural ground vibration is higher than expected. A mechanical model of a room temperature linear collider final focus magnet has been constructed and actively stabilized with an accelerometer based system.
Date: September 28, 2006
Creator: Frisch, Josef; Chang, Allison; Decker, Valentin; Doyle, Eric; Eriksson, Leif; Hendrickson, Linda et al.
Object Type: Article
System: The UNT Digital Library
On the Putative Detection of Z>0 X-Ray Absorption Features in the Spectrum of Mrk 421 (open access)

On the Putative Detection of Z>0 X-Ray Absorption Features in the Spectrum of Mrk 421

In a series of papers, Nicastro et al. have claimed the detection of z > 0 O VII absorption features in the spectrum of Mrk 421 obtained with the Chandra Low Energy Transmission Grating Spectrometer (LETGS). We evaluate those claims in the context of a high quality spectrum of the same source obtained with the Reflection Grating Spectrometer (RGS) on XMM-Newton. The data comprise over 955 ksec of usable exposure time and more than 2.6 x 10{sup 4} counts per 50 m{angstrom} at 21.6 {angstrom}. We concentrate on the spectrally clean region (21.3 < {lambda} < 22.5 {angstrom}) where sharp features due to the astrophysically abundant O VII may reveal an intervening, warm-hot intergalactic medium (WHIM). In spite of the fact that the sensitivity of the RGS data is higher than that of the original LETGS data presented by Nicastro et al., we do not confirm detection of any of the intervening systems claimed to date. Rather, we detect only three unsurprising, astrophysically expected features down to the log (N{sub i}) {approx} 14.6 (3{sigma}) sensitivity level. Each of the two purported WHIM features is rejected with a statistical confidence that exceeds that reported for its initial detection. While we can …
Date: April 28, 2006
Creator: Rasmussen, Andrew P.; /SLAC /KIPAC, Menlo Park; Kahn, Steven M.; /SLAC /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Paerels, Frits; /Columbia U., Astron. Astrophys. et al.
Object Type: Report
System: The UNT Digital Library
The O VII X-Ray Forest Toward Markarian 421: Consistency between XMM-Newton and Chandra (open access)

The O VII X-Ray Forest Toward Markarian 421: Consistency between XMM-Newton and Chandra

Recently the first detections of highly ionized gas associated with two Warm-Hot Intergalactic Medium (WHIM) filaments have been reported. The evidence is based on X-ray absorption lines due to O VII and other ions observed by Chandra towards the bright blazar Mrk 421. We investigate the robustness of this detection by a re-analysis of the original Chandra LETGS spectra, the analysis of a large set of XMM-Newton RGS spectra of Mrk 421, and additional Chandra observations. We address the reliability of individual spectral features belonging to the absorption components, and assess the significance of the detection of these components. We also use Monte Carlo simulations of spectra. We confirm the apparent strength of several features in the Chandra spectra, but demonstrate that they are statistically not significant. This decreased significance is due to the number of redshift trials that are made and that are not taken into account in the original discovery paper. Therefore these features must be attributed to statistical fluctuations. This is confirmed by the RGS spectra, which have a higher signal to noise ratio than the Chandra spectra, but do not show features at the same wavelengths. Finally, we show that the possible association with a Ly{alpha} …
Date: April 28, 2006
Creator: Kaastra, J. S.; Werner, N.; den Herder, J. W. A.; /SRON, Utrecht; Paerels, F. B. S.; /Columbia U., Astron. Astrophys. et al.
Object Type: Report
System: The UNT Digital Library
Mechanically Cooled Large-Volume Germanium Detector Systems for Nuclear Explosion Monitoring DOENA27323-1 (open access)

Mechanically Cooled Large-Volume Germanium Detector Systems for Nuclear Explosion Monitoring DOENA27323-1

Compact maintenance free mechanical cooling systems are being developed to operate large volume germanium detectors for field applications. To accomplish this we are utilizing a newly available generation of Stirling-cycle mechanical coolers to operate the very largest volume germanium detectors with no maintenance. The user will be able to leave these systems unplugged on the shelf until needed. The flip of a switch will bring a system to life in ~ 1 hour for measurements. The maintenance-free operating lifetime of these detector systems will exceed 5 years. These features are necessary for remote long-duration liquid-nitrogen free deployment of large-volume germanium gamma-ray detector systems for Nuclear Explosion Monitoring. The Radionuclide Aerosol Sampler/Analyzer (RASA) will greatly benefit from the availability of such detectors by eliminating the need for liquid nitrogen at RASA sites while still allowing the very largest available germanium detectors to be reliably utilized.
Date: July 28, 2006
Creator: Hull, E.L.
Object Type: Report
System: The UNT Digital Library
Recent tau Physics Studies at BaBar (open access)

Recent tau Physics Studies at BaBar

Recent results from {tau} physics studies at BABAR are presented with an emphasis on hadronic decays and lepton flavor violation studies.
Date: July 28, 2006
Creator: Wilson, F. F.
Object Type: Article
System: The UNT Digital Library
Multiscale Thermohydrologic Model Supporting the Licence Application for the Yucca Mountain Repository (open access)

Multiscale Thermohydrologic Model Supporting the Licence Application for the Yucca Mountain Repository

The MultiScale ThermoHydrologic Model (MSTHM) predicts thermal-hydrologic (TH) conditions within emplacement tunnels (drifts) and in the adjoining host rock at Yucca Mountain, Nevada, which is the proposed site for a radioactive waste repository in the US. Because these predictions are used in the performance assessment of the Yucca Mountain repository, they must address the influence of variability and uncertainty of the engineered- and natural-system parameters that significantly influence those predictions. Parameter-sensitivity studies show that the MSTHM predictions adequately propagate the influence of parametric variability and uncertainty. Model-validation studies show that the influence of conceptual-model uncertainty on the MSTHM predictions is insignificant compared to that of parametric uncertainty, which is propagated through the MSTHM.
Date: March 28, 2006
Creator: Buscheck, T.A>; Sun, Y. & Hao, Y.
Object Type: Article
System: The UNT Digital Library
The First Lasing of 193 Nm Sase, 4th Harmonic Hghg and Esase at the Nsls Sdl. (open access)

The First Lasing of 193 Nm Sase, 4th Harmonic Hghg and Esase at the Nsls Sdl.

The first lasing of three types of single-pass high-gain FELs, SASE at 193 nm, 4th harmonic HGHG at 199 nm and ESASE at the Source Development Lab (SDL) of Brookhaven National Laboratory (BNL) is reported. The saturation of 4th harmonic HGHG and ESASE FELs was observed. We also observed the spectral broadening and instability of the 4th harmonic HGHG.
Date: August 28, 2006
Creator: Wang, X. J.; Shen, Y.; Watanabe, T.; Murphy, J. B.; Rose, J. & Tsang, T.
Object Type: Article
System: The UNT Digital Library
Concept for lightweight spaced-based deposition technology (open access)

Concept for lightweight spaced-based deposition technology

In this contribution we will describe a technology path to very high quality coatings fabricated in the vacuum of space. To accomplish the ambitious goals set out in NASA's Lunar-Mars proposal, advanced thin-film deposition technology will be required. The ability to deposit thin-film coatings in the vacuum of lunar-space could be extremely valuable for executing this new space mission. Developing lightweight space-based deposition technology (goal:<300 g, including power supply) will enable the future fabrication and repair of flexible large-area space antennae and fixed telescope mirrors for lunar-station observatories. Filtered Cathodic Arc (FCA) is a proven terrestrial energetic thin-film deposition technology that does not need any processing gas but is well suited for ultra-high vacuum operation. Recently, miniaturized cathodic arcs have already been developed and considered for space propulsion. It is proposed to combine miniaturized pulsed FCA technology and robotics to create a robust, enabling space-based deposition system for the fabrication, improvement, and repair of thin films, especially of silver and aluminum, on telescope mirrors and eventually on large area flexible substrates. Using miniature power supplies with inductive storage, the typical low-voltage supply systems used in space are adequate. It is shown that high-value, small area coatings are within the reach …
Date: February 28, 2006
Creator: Fulton, Michael & Anders, Andre
Object Type: Article
System: The UNT Digital Library
Analysis of a Gross Counting Decision Metric for use in Threat Detection During Cargo Container Inspection (open access)

Analysis of a Gross Counting Decision Metric for use in Threat Detection During Cargo Container Inspection

LLNL is actively engaged in the development of a variety of advanced technologies for use in detecting potential threats in sea-going cargo containers, particularly the presence of hidden special nuclear materials (SNM). One such project is the so-called ''Nuclear Car Wash'' (NCW), which uses a high-energy neutron probe to scan the container. High-energy, {beta}-delayed {gamma}-rays emitted during the decay of short-lived, neutron-induced fission products are then taken as a signature of fissionable material. There are a number of different threat decision metrics that one could imagine using in conjunction with an inspection system such as the NCW; however, the most straightforward approach might be to simply compare the total number of counts that our detector records during some suitably chosen time interval to the average background signal that one would expect from a ''clean'' container during the same interval. The purpose of this report is to describe the basic statistical properties of a decision metric of this sort and outline the procedures for using it in experimental practice.
Date: April 28, 2006
Creator: Hall, J
Object Type: Report
System: The UNT Digital Library
CO2 Capture by Absorption with Potassium Carbonate (open access)

CO2 Capture by Absorption with Potassium Carbonate

The objective of this work is to improve the process for CO{sub 2} capture by alkanolamine absorption/stripping by developing an alternative solvent, aqueous K{sub 2}CO{sub 3} promoted by piperazine. The pilot plant data have been reconciled using 17% inlet CO{sub 2}. A rate-based model demonstrates that the stripper is primarily controlled by liquid film mast transfer resistance, with kinetics at vacuum and diffusion of reactants and products at normal pressure. An additional major unknown ion, probably glyoxylate, has been observed in MEA degradation. Precipitation of gypsum may be a feasible approach to removing sulphate from amine solutions and providing for simultaneous removal of CO{sub 2} and SO{sub 2}. Corrosion of carbon steel in uninhibited MEA solution is increased by increased amine concentration, by addition of piperazine, and by greater CO{sub 2} loading.
Date: July 28, 2006
Creator: Rochelle, Gary T.; Chen, Eric; Oyenekan, Babatunde; Sexton, Andrew; Davis, Jason; Hilliard, Marcus et al.
Object Type: Report
System: The UNT Digital Library
UPTAKE OF RADIONUCLIDE METALS BY SPME FIBERS (open access)

UPTAKE OF RADIONUCLIDE METALS BY SPME FIBERS

The Federal Bureau of Investigation (FBI) Laboratory currently does not have on site facilities for handling radioactive evidentiary materials and there are no established FBI methods or procedures for decontaminating high explosive (HE) and fire debris (FD) evidence while maintaining evidentiary value. One experimental method for the isolation of HE and FD residue involves using solid phase microextraction or SPME fibers to remove residue of interest. Due to their high affinity for organics, SPME fibers should have little affinity for most metals. However, no studies have measured the affinity of radionuclides for SPME fibers. The focus of this research was to examine the affinity of dissolved radionuclide ({sup 239/240}Pu, {sup 238}U, {sup 237}Np, {sup 85}Sr, {sup 133}Ba, {sup 137}Cs, {sup 60}Co and {sup 226}Ra) and stable radionuclide surrogate metals (Sr, Co, Ir, Re, Ni, Ba, Cs, Nb, Zr, Ru, and Nd) for SPME fibers at the exposure conditions that favor the uptake of HE and FD residues. Our results from radiochemical and mass spectrometric analyses indicate these metals have little measurable affinity for these SPME fibers during conditions that are conducive to HE and FD residue uptake with subsequent analysis by liquid or gas phase chromatography with mass spectrometric detection.
Date: August 28, 2006
Creator: Duff, M; S Crump, S; Robert02 Ray, R; Keisha Martin, K & Donna Beals, D
Object Type: Article
System: The UNT Digital Library
Hanford Site Environmental Surveillance Data Report for Calendar Year 2005 (open access)

Hanford Site Environmental Surveillance Data Report for Calendar Year 2005

This data report contains the actual raw data used to create the tables and summaries in the Hanford Site Environmental Report for Calendar Year 2005. In addition to providing raw data collected during routine sampling efforts in 2005, this data report also includes Columbia River shoreline spring data collected by the PNNL Groundwater Performance Assessment Project, and data from collaborative studies performed by the PNNL during 2005 under partial support by the SESP. Some analytical results were not received in time to include in this report or changes may have occurred to the data following publication.
Date: September 28, 2006
Creator: Bisping, Lynn E.
Object Type: Report
System: The UNT Digital Library
Sulfur K-Edge XAS and DFT Calculations on P450 ModelComplexes: Effects of Hydrogen Bonding on Electronic Structure and RedoxPotentials (open access)

Sulfur K-Edge XAS and DFT Calculations on P450 ModelComplexes: Effects of Hydrogen Bonding on Electronic Structure and RedoxPotentials

None
Date: September 28, 2006
Creator: Dey, Abhishek; Okamura, Taka-aki; Ueyama, Norikazu; Hedman, Britt; Hodgson, Keith O.; Solomon, Edward I. et al.
Object Type: Article
System: The UNT Digital Library
Evaluation of Ultra Clean Fuels from Natural Gas (open access)

Evaluation of Ultra Clean Fuels from Natural Gas

ConocoPhillips, in conjunction with Nexant Inc., Penn State University, and Cummins Engine Co., joined with the U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) in a cooperative agreement to perform a comprehensive study of new ultra clean fuels (UCFs) produced from remote sources of natural gas. The project study consists of three primary tasks: an environmental Life Cycle Assessment (LCA), a Market Study, and a series of Engine Tests to evaluate the potential markets for Ultra Clean Fuels. The overall objective of DOE's Ultra Clean Transportation Fuels Initiative is to develop and deploy technologies that will produce ultra-clean burning transportation fuels for the 21st century from both petroleum and non-petroleum resources. These fuels will: (1) Enable vehicles to comply with future emission requirements; (2) Be compatible with the existing liquid fuels infrastructure; (3) Enable vehicle efficiencies to be significantly increased, with concomitantly reduced CO{sub 2} emissions; (4) Be obtainable from a fossil resource, alone or in combination with other hydrocarbon materials such as refinery wastes, municipal wastes, biomass, and coal; and (5) Be competitive with current petroleum fuels. The objectives of the ConocoPhillips Ultra Clean Fuels Project are to perform a comprehensive life cycle analysis and to conduct …
Date: February 28, 2006
Creator: Abbott, Robert; Casey, Edward; Esen, Etop; Smith, Douglas; Burke, Bruce; Nguyen, Binh et al.
Object Type: Report
System: The UNT Digital Library
Hanford Site Environmental Report for Calendar Year 2005 (open access)

Hanford Site Environmental Report for Calendar Year 2005

This report, published annually since 1958, includes information and summary analytical data that (1) provide an overview of activities at the Hanford Site during calendar year 2005; (2) demonstrate the site's compliance with applicable federal, state, and local environmental laws and regulations, executive orders, and U.S. Department of Energy (DOE) policies and directives; (3) characterize Hanford Site environmental management performance; and (4) highlight significant environmental programs.
Date: September 28, 2006
Creator: Poston, Ted M.; Hanf, Robert W.; Dirkes, Roger L. & Morasch, Launa F.
Object Type: Report
System: The UNT Digital Library
Photoelectron Emission Studies in CsBr at 257 nm (open access)

Photoelectron Emission Studies in CsBr at 257 nm

CsBr/Cr photocathodes were found [1,2] to meet the requirements of a multi-electron beam lithography system operating with a light energy of 4.8 eV (257nm). The fact that photoemission was observed with a light energy below the reported 7.3 eV band gap for CsBr was not understood. This paper presents experimental results on the presence of intra-band gap absorption sites (IBAS) in CsBr thin film photo electron emitters, and presents a model based on IBAS to explain the observed photoelectron emission behavior at energies below band gap. A fluorescence band centered at 330 nm with a FWHM of about 0.34 eV was observed in CsBr/Cr samples under 257 nm laser illumination which can be attributed to IBAS and agrees well with previously obtained synchrotron photoelectron spectra[1] from the valence band of CsBr films.
Date: September 28, 2006
Creator: Maldonado, Juan R.; Liu, Zhi; Sun, Yun; Pianetta, Piero A.; Pease, Fabian W. & /Stanford U., Elect. Eng. Dept. /SLAC, SSRL
Object Type: Article
System: The UNT Digital Library
Hanford Site Near-Facility Environmental Monitoring Data Report for Calendar Year 2005 (open access)

Hanford Site Near-Facility Environmental Monitoring Data Report for Calendar Year 2005

This Appendix contains brief discussions, specific sampling location information, and complete analytical data results for the various near-facility environmental monitoring efforts for 2005. Detailed discussions and summarized analytical results are provided in PNNL-15892, Hanford Site Environmental Report for Calendar Year 2005.
Date: September 28, 2006
Creator: Perkins, Craig J.; Dorsey, Michael C.; Mckinney, Stephen M. & Mitchell, Ronald M.
Object Type: Report
System: The UNT Digital Library
Rare And Radiative B Meson Decays From the BaBar Experiment (open access)

Rare And Radiative B Meson Decays From the BaBar Experiment

Since its start in 1999 the BABAR experiment has collected a vast amount of data. Electron-positron collisions at the energy of the {Upsilon}(4S) resonance have produced about 240 million coherent B{sup 0}{bar B}{sup 0} and B{sup +}B{sup -} pairs, opening the doors for exploration of rare B meson decays. An overview of the electroweak penguin physics program of BABAR is given, the analysis of two specific decays is presented in detail.
Date: August 28, 2006
Creator: Stelzer, J.
Object Type: Article
System: The UNT Digital Library
Powder River Coal Plant Wide Assessment (open access)

Powder River Coal Plant Wide Assessment

Energy savings assessment of coal mine
Date: April 28, 2006
Creator: Fosmo, Glenn B.
Object Type: Report
System: The UNT Digital Library