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Anode Sheath Switching in a Carbon Nanotube Arc Plasma

Description: The anode ablation rate is investigated as a function of anode diameter for a carbon nanotube arc plasma. It is found that anomalously high ablation occurs for small anode diameters. This result is explained by the formation of a positive anode sheath. The increased ablation rate due to this positive anode sheath could imply greater production rate for carbon nanotubes.
Date: April 8, 2008
Creator: Abe Fetterman, Yevgeny Raitses, and Michael Keidar
Partner: UNT Libraries Government Documents Department

Bendable X-ray Optics at the ALS: Design, Tuning, Performance and Applications

Description: We review the development at the Advanced Light Source (ALS) of bendable x-ray optics widely used for focusing of beams of soft and hard x-rays. Typically, the focusing is divided in the tangential and sagittal directions into two elliptically cylindrical reflecting elements, the so-called Kirkpatrick-Baez (KB) pair [1]. Because fabrication of elliptical surfaces is complicated, the cost of directly fabricated tangential elliptical cylinders is often prohibitive. This is in contrast to flat optics, that are simpler to manufacture and easier to measure by conventional interferometry. The figure of a flat substrate can be changed by placing torques (couples) at each end. Equal couples form a tangential cylinder, and unequal couples can approximate a tangential ellipse or parabola. We review the nature of the bending, requirements and approaches to the mechanical design, and describe a technique developed at the ALS Optical Metrology Laboratory (OML) for optimal tuning of bendable mirrors before installation in the beamline [2]. The tuning technique adapts a method previously used to adjust bendable mirrors on synchrotron radiation beamlines [3]. However, in our case, optimal tuning of a bendable mirror is based on surface slope trace data obtained with a slope measuring instrument--in our case, the long trace profiler (LTP). We show that due to the near linearity of the bending problem, the minimal set of data, necessary for tuning of two benders, consists of only three slope traces measured before and after a single adjustment of each bending couple. We provide an algorithm that was used in dedicated software for finding optimal settings for the mirror benders. The algorithm is based on the method of regression analysis with experimentally found characteristic functions of the benders. The resulting approximation to the functional dependence of the desired slope shape provides nearly final settings for the benders. Moreover, the characteristic ...
Date: September 8, 2008
Creator: Advanced Light Source, Lawrence Berkeley National Laboratory; Yashchuk, Valeriy V.; Church, Matthew N.; Knight, Jason W.; Kunz, Martin; MacDowell, Alastair A. et al.
Partner: UNT Libraries Government Documents Department

X-ray absorption study of the electronic structure of Mn-doped amorphous Si

Description: The electronic structure of Mn in amorphous Si (a-Mn{sub x}Si{sub 1?x}) is studied by X-ray absorption spectroscopy at the Mn L{sub 3,2} edges for x = 0.005-0.18. Except the x = 0.005 sample, which shows a slight signature of Mn{sup 2+} atomic multiplets associated with a local Mn moment, all samples have broad and featureless L{sub 3,2} absorption peaks, corresponding to an itinerant state for all 3d electrons. The broad X-ray absorption spectra exclude the possibility of a localized 3d moment and explain the unexpectedly quenched Mn moment in this magnetically-doped amorphous semiconductor. Such a fully delocalized d state of Mn dopant in Si has not been previously suggested.
Date: March 8, 2008
Creator: Arenholz, Elke; Zeng, Li; Huegel, A.; Helgren, E.; Hellman, F.; Piamonteze, C. et al.
Partner: UNT Libraries Government Documents Department

Evaluation of Salmon Spawning Below Bonneville Dam Annual Report October 2006 - September 2007.

Description: From 1999 through 2007, the Fish and Wildlife Program of the Bonneville Power Administration funded a project to determine the number of fall Chinook and chum salmon spawning downstream of Bonneville Dam, the characteristics of their spawning areas, and the flows necessary to ensure their long-term survival. Data were collected to ensure that established flow guidelines are appropriate and provide adequate protection for the species of concern. The projects objectives are consistent with the high priority placed by the Northwest Power and Conservation Council Independent Scientific Advisory Board and the salmon managers on determining the importance of mainstem habitats to the production of salmon in the Columbia River Basin. Because of the influence of mainstem habitat on salmon production, there is a continued need to better understand the physical habitat variables used by mainstem fall Chinook and chum salmon populations and the effects of hydropower project operations on spawning and incubation. During FY 2007, Pacific Northwest National Laboratory focused on (1) locating and mapping deep-water fall Chinook salmon and chum salmon spawning areas, (2) investigating the interaction between groundwater and surface water near fall Chinook and chum salmon spawning areas, and (3) providing in-season hyporheic temperature and water surface elevation data to assist state agencies with emergence timing and redd dewatering estimates. This report documents the studies and tasks performed by PNNL during FY 2007. Chapter 1 provides a description of the searches conducted for deepwater redds-adjacent to Pierce and Ives islands for fall Chinook salmon and near the Interstate 205 bridge for chum salmon. The chapter also provides data on redd location, information about habitat associations, and estimates of total spawning populations. Chapter 2 documents the collection of data on riverbed and river temperatures and water surface elevations, from the onset of spawning to the end of emergence, and ...
Date: August 8, 2008
Creator: Arntzen, Evan V.; Mueller, Robert P.; Murray, Katherine J. & Bott, Yi-Ju
Partner: UNT Libraries Government Documents Department

Measurement of D^0-\overline{D^0} Mixing using the Ratio of Lifetimes for the Decays D^0 \to K^-\pi^+, K^-K^+, and \pi^-\pi^+

Description: The authors present a measurement of D{sup 0}-{bar D}{sup 0} mixing parameters using the ratios of lifetimes extracted from a sample of D{sup 0} mesons produced through the process D*{sup +} {yields} D{sup 0}{pi}{sup +}, that decay to K{sup -}{pi}{sup +}, I{sup -}K{sup +}, or {pi}{sup -}{pi}{sup +}. the Cabibbo-suppressed modes K{sup -}K{sup +} and {pi}{sup -}{pi}{sup +} are compared to the Cabibbo-favored mode K{sup -}{pi}{sup +} to obtain a measurement of ycp, which in the limit of CP conservation corresponds to the mixing parameter y. The analysis is based on a data sample of 384 fb{sup -1} collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider. They obtain ycp = [1.24 {+-} 0.39(stat) {+-} 0.13(syst)]%, which is evidence of D{sup 0}-{bar D}{sup 0} mixing at the 3{sigma} level, and {Delta}Y = [-0.26 {+-} 0.36(stat) {+-} 0.08(syst)]%, where {Delta}Y constrains possible CP violation. Combining this result with a previous BABAR measurement of ycp obtained from a separate sample of D{sup 0} {yields} K{sup -}K{sup +} events, they obtain ycp = [1.03 {+-} 0.33(stat) {+-} 0.19(syst)]%.
Date: January 8, 2008
Creator: Aubert, B
Partner: UNT Libraries Government Documents Department

A Measurement of the Branching Fractions ofexclusive Bbar to D(*)(pi)lnu Decays in Events with a Fully Reconstructed BMeson

Description: The authors report a measurement of the branching fractions for {bar B} {yields} D{sup (*)}{pi}{ell}{sup -}{bar {nu}}{sub {ell}} decays based on 341.1 fb{sup -1} of data collected at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II e{sup +}e{sup -} storage rings. Events are tagged by fully reconstructing one of the B mesons in a hadronic decay mode. The obtain {Beta}(B{sup -} {yields} D{sup 0}{ell}{sup -}{bar {nu}}{sub {ell}}) = (2.33 {+-} 0.09{sub stat.} {+-} 0.09{sub syst.})%, {Beta}(B{sup -} {yields} D*{sup 0}{ell}{sup -}{bar {nu}}{sub {ell}}) = 5.83 {+-} 0.15{sub stat.} {+-} 0.30{sub syst.}%, {Beta}({bar B}{sup 0} {yields} D{sup +}{ell}{sup -}{bar {nu}}{sub {ell}}) = (2.21 {+-} 0.11{sub stat.} {+-} 0.12{sub syst.})% {Beta}({bar B}{sup 0} {yields} D*{sup +}{ell}{sup -}{bar {nu}}{sub {ell}}) = 5.49 {+-} 0.16{sub stat.} {+-} 0.25{sub syst.}%, {Beta}(B{sup -} {yields} D{sup +}{pi}{sup -}{ell}{sup -}{bar {nu}}{sub {ell}}) = (0.42 {+-} 0.06{sub stat.} {+-} 0.03{sub syst.})%, {Beta}(B{sup -} {yields} D*{sup +} {pi}{sup -}{ell}{sup -}{bar {nu}}{sub {ell}}) = (0.59 {+-} 0.05{sub stat.} {+-} 0.04{sub syst.})%, {Beta}({bar B}{sup 0} {yields} D{sup 0}{pi}{sup +}{ell}{sup -}{bar {nu}}{sub {ell}}) = (0.43 {+-} 0.08{sub stat.} {+-} 0.03{sub syst.})% and {Beta}({bar B}{sup 0} {yields} D*{sup 0} {pi}{sup +}{ell}{sup -}{bar {nu}}{sub {ell}}) = (0.48 {+-} 0.08{sub stat.} {+-} 0.04{sub syst.})%.
Date: January 8, 2008
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department

A CW normal-conductive RF gun for free electron laser and energy recovery linac applications

Description: Currently proposed energy recovery linac and high average power free electron laser projects require electron beam sources that can generate up to {approx} 1 nC bunch charges with less than 1 mmmrad normalized emittance at high repetition rates (greater than {approx} 1 MHz). Proposed sources are based around either high voltage DC or microwave RF guns, each with its particular set of technological limits and system complications. We propose an approach for a gun fully based on mature RF and mechanical technology that greatly diminishes many of such complications. The concepts for such a source as well as the present RF and mechanical design are described. Simulations that demonstrate the beam quality preservation and transport capability of an injector scheme based on such a gun are also presented.
Date: October 8, 2008
Creator: Baptiste, Kenneth; Corlett, John; Kwiatkowski, Slawomir; Lidia, Steven; Qiang, Ji; Sannibale, Fernando et al.
Partner: UNT Libraries Government Documents Department

Impact of air-exposure on the chemical and electronic structure ofZnO:Zn3N2 thin films

Description: The chemical and electronic surface structure of ZnO:Zn3N2 ("ZnO:N") thin films with different N contents was investigated by soft x-ray emission spectroscopy. Upon exposure to ambient air (in contrast to storage in vacuum), the chemical and electronic surface structure of the ZnO:N films changes substantially. In particular, we find that the Zn3N2/(Zn3N2+ZnO) ratio decreases with exposure time and that this change depends on the initial N content. We suggest a degradation mechanism based on the reaction of the Zn3N2 content with atmospheric humidity.
Date: September 8, 2008
Creator: Bar, M.; Ahn, K.-S.; Shet, S.; Yan, Y.; Weinhardt, L.; Fuchs, O. et al.
Partner: UNT Libraries Government Documents Department

Report of a Workshop on Parallelization of Coupled Cluster Methods

Description: The benchmark, ab initio quantum mechanical methods for molecular structure and spectra are now recognized to be coupled-cluster theory. To benefit from the transiiton to tera- and petascale computers, such coupled-cluster methods must be created to run in a scalable fashion. This Workshop, held as a aprt of the 48th annual Sanibel meeting, at St. Simns, Island, GA, addressed that issue. Representatives of all the principal scientific groups who are addressing this topic were in attendance, to exchange information about the problem and to identify what needs to be done in the future. This report summarized the conclusions of the workshop.
Date: May 8, 2008
Creator: Bartlett, Rodney J. & Deumens, Erik
Partner: UNT Libraries Government Documents Department

Development of a low-power, low-cost front end electronics module for large scale distributed neutrino detectors

Description: A number of concepts have been presented for distributed neutrino detectors formed of large numbers of autonomous detectors. Examples include the Antarctic Ross Ice Shelf Antenna Neutrino Array (ARIANNA) [Barwick 2006], as well as proposed radio extensions to the IceCube detector at South Pole Station such as AURA and IceRay. [Besson 2008]. We have focused on key enabling technical developments required by this class of experiments. The radio Cherenkov signal, generated by the Askaryan mechanism [Askaryan 1962, 1965], is impulsive and coherent up to above 1 GHz. In the frequency domain, the impulsive character of the emission results in simultaneous increase of the power detected in multiple frequency bands. This multiband triggering approach has proven fruitful, especially as anthropogenic interference often results from narrowband communications signals. A typical distributed experiment of this type consists of a station responsible for the readout of a cluster of antennas either near the surface of the ice or deployed in boreholes. Each antenna is instrumented with a broadband low-noise amplifier, followed by an array of filters to facilitate multi-band coincidence trigger schemes at the antenna level. The power in each band is detected at the output of each band filter, using either square-law diode detectors or log-power detectors developed for the cellular telephone market. The use of multiple antennas per station allows a local coincidence among antennas to be used as the next stage of the trigger. Station triggers can then be combined into an array trigger by comparing timestamps of triggers among stations and identifying space-time clusters of station triggers. Data from each station is buffered and can be requested from the individual stations when a multi-station coincidence occurs. This approach has been successfully used in distributed experiments such as the Pierre Auger Observatory. [Abraham et al. 2004] We identified the filters as ...
Date: March 8, 2008
Creator: Beatty, James J. & Kass, Richard D.
Partner: UNT Libraries Government Documents Department

Tax Gap: Proposals in the 110th Congress to Require Brokers to Report Basis on Publicly Traded Securities

Description: Recent and projected large deficits and the need for revenue to offset spending or tax reduction proposals generated congressional and executive branch interest in different proposals to reduce the tax gap; and consequently, raise additional revenue. Proposals in the 110th Congress to require brokers to report adjusted basis on publicly traded securities sold by individuals are examined in this report.
Date: October 8, 2008
Creator: Bickley, James M.
Partner: UNT Libraries Government Documents Department

The Gulf Security Dialogue and Related Arms Sale Proposals

Description: This report describes the structure and objectives of the Gulf Security Dialogue; briefly assesses its regional implications; summarizes related proposed arms sales; provides an overview of congressional notification and review procedures; and analyzes recent related activity in the Administration and Congress.
Date: October 8, 2008
Creator: Blanchard, Christopher M. & Grimmett, Richard R.
Partner: UNT Libraries Government Documents Department

Diagnostic Components in Harsh Radiation Environments: Possible Overlap in R&D Requirements of IC and MF Systems

Description: The next generation of large scale fusion devices--ITER/LMJ/NIF--will require diagnostic components to operate in environments far more severe than those encountered in present facilities. This harsh environment will be induced by fluxes of neutrons, gamma rays, energetic ions, electromagnetic radiation, and in some cases debris and shrapnel, at levels several orders of magnitude higher than those experienced in today's devices. For several years the question of possible synergy between inertial and the magnetic confinement research has been pursued by members of the respective communities. A first joint workshop specifically devoted to the identification and promotion of these synergies was organized in France, at Aix-en-Provence from June 27th to 29th, 2007. The workshop was attended by about 50 invited specialists. The participants identified a number of subject areas where common overlapping interests could benefit from additional interactions and meetings: windows, optical fibers, mirrors, cables, electronic components and 14 MeV neutron sources. In this paper we summarize the findings of these working groups. We put the discussion into context by including a brief description of the environments and the physical effects that have to be handled.
Date: May 8, 2008
Creator: Bourgade, J L; Costley, A E; Reichle, R; Hodgson, E R; Hsing, W; Glebov, V et al.
Partner: UNT Libraries Government Documents Department

Unauthorized Alien Students: Issues and "DREAM Act" Legislation

Description: Multiple bills have been introduced in recent Congresses to address the unauthorized student population. While there are other options for dealing with this population, this report deals exclusively with the DREAM Act approach of proposing relief for unauthorized students in light of the widespread congressional interest in it.
Date: January 8, 2008
Creator: Bruno, Andorra
Partner: UNT Libraries Government Documents Department

Fishery, Aquaculture, and Marine Mammal Legislation in the 110th Congress

Description: Aquaculture — the farming of fish, shellfish, and other aquatic animals and plants in a controlled environment — is expanding rapidly abroad, with more modest advances in the United States. This report discusses the federal laws and regulations that guide the management of resources in open ocean and near-shore coastal areas.
Date: October 8, 2008
Creator: Buck, Eugene H.
Partner: UNT Libraries Government Documents Department

Field Flows of Dark Energy

Description: Scalar field dark energy evolving from a long radiation- or matter-dominated epoch has characteristic dynamics. While slow-roll approximations are invalid, a well defined field expansion captures the key aspects of the dark energy evolution during much of the matter-dominated epoch. Since this behavior is determined, it is not faithfully represented if priors for dynamical quantities are chosen at random. We demonstrate these features for both thawing and freezing fields, and for some modified gravity models, and unify several special cases in the literature.
Date: July 8, 2008
Creator: Cahn, Robert N.; de Putter, Roland & Linder, Eric V.
Partner: UNT Libraries Government Documents Department

The integrated Status and Effectiveness Monitoring Program : U.S. Forest Service Fish Abundance and Steelhead Redd Surveys Annual Report : January 1 - December 31, 2008.

Description: This contract report is one of a series of reports that document implementation components of the Bonneville Power Administration's (BPA) funded project: Integrated Status and Effectiveness Monitoring Program (ISEMP - BPA project No.2003-017-00, Chris Jordan, NOAA-NWFSC project sponsor). Other components of the project are separately reported, as explained below. The ISEMP project has been created as a cost effective means of developing protocols and new technologies, novel indicators, sample designs, analytical data management, communication tools and skills, and restoration experiments that support the development of a region-wide Research, Monitoring, and Evaluation (RME) program to assess the status of anadromous salmonids populations, their tributary habitat and restoration and management actions. The most straightforward approach to developing a regional-scale monitoring and evaluation program would be to increase standardization among status and trend monitoring programs. However, the diversity of species and their habitat, as well as the overwhelming uncertainty surrounding indicators, metrics, and data interpretation methods requires the testing of multiple approaches. Thus, ISEMP has adopted an approach to develop a broad template that may differ in the details among subbasins, but one that will ultimately lead to the formation of a unified RME process for the management of anadromous salmonid populations and habitat across the Columbia River Basin. ISEMP has been initiated in three pilot areas, the Wenatchee/Entiat, John Day, and Salmon. To balance replicating experimental approaches with the goal of developing monitoring and evaluation tools that apply as broadly as possible across the Pacific Northwest, these subbasins were chosen as representative of a wide range of potential challenges and conditions, e.g., differing fish species composition and life histories, ecoregions, institutional settings, and existing data. ISEMP has constructed a framework that builds on current status and trend monitoring infrastructures in these pilot subbasins, but challenges current programs by testing alternative monitoring approaches. ...
Date: December 8, 2008
Creator: Call, Justin
Partner: UNT Libraries Government Documents Department

Remaining Sites Verification Package for the 100-F-46, 119-F Stack Sampling French Drain, Waste Site Reclassification Form 2008-021

Description: The 100-F-46 french drain consisted of a 1.5 to 3 m long, vertically buried, gravel-filled pipe that was approximately 1 m in diameter. Also included in this waste site was a 5 cm cast-iron pipeline that drained condensate from the 119-F Stack Sampling Building into the 100-F-46 french drain. In accordance with this evaluation, the confirmatory sampling results support a reclassification of this site to No Action. The current site conditions achieve the remedial action objectives and the corresponding remedial action goals established in the Remaining Sites ROD. The results of confirmatory sampling show that residual contaminant concentrations do not preclude any future uses and allow for unrestricted use of shallow zone soils. The results also demonstrate that residual contaminant concentrations are protective of groundwater and the Columbia River.
Date: August 8, 2008
Creator: Capron, J. M.
Partner: UNT Libraries Government Documents Department