Direct Comparison of Brookhaven Reflectivity Measurements with Free-Electron Theory (open access)

Direct Comparison of Brookhaven Reflectivity Measurements with Free-Electron Theory

The reflectivity at normal incidence of copper and aluminum samples was recently measured over a large frequency range at Brookhaven by one of us (JT). Then using the Kramers-Kroning integrals, and assuming the free-electron model of conductivity, the dependence of conductivity on frequency was obtained. The results seemed to suggest, for example, that the dc conductivities of the copper and evaporated aluminum samples are a factor of 3 lower than expected. We propose in this report, instead, directly fitting the free-electron model to the low frequency end of the reflectivity data. This fitting does not depend on the higher frequency results and on Kramers-Kronig integrations, but it does assume that the data at the low frequency end is sufficiently accurate. Note that for our LCLS wakefield studies, it is only over these (relatively) low frequencies that we need to know the electrical properties of the metals. The equations that relate reflectivity R with the free electron parameters dc conductivity {sigma} and relaxation time {tau} are: (1) {tilde {sigma}} = {sigma}/1-ikc{tau}; (2) {tilde n} = {radical} {tilde {epsilon}} = {radical}(1+4{pi}i{tilde k}c/{omega}); and (3) R = |{tilde n}-1/{tilde n} + 1|{sup 2}. The parameters are ac conductivity {tilde {sigma}}, index of refraction …
Date: December 13, 2010
Creator: Bane, Karl L.F.
Object Type: Report
System: The UNT Digital Library
Tracking the Sun III; The Installed Cost of Photovoltaics in the United States from 1998-2009 (open access)

Tracking the Sun III; The Installed Cost of Photovoltaics in the United States from 1998-2009

Installations of solar photovoltaic (PV) systems have been growing at a rapid pace in recent years. In 2009, approximately 7,500 megawatts (MW) of PV were installed globally, up from approximately 6,000 MW in 2008, consisting primarily of grid-connected applications. With 335 MW of grid-connected PV capacity added in 2009, the United States was the world's fourth largest PV market in 2009, behind Germany, Italy, and Japan. The market for PV in the United States is driven by national, state, and local government incentives, including up-front cash rebates, production-based incentives, requirements that electricity suppliers purchase a certain amount of solar energy, and federal and state tax benefits. These programs are, in part, motivated by the popular appeal of solar energy, and by the positive attributes of PV - modest environmental impacts, avoidance of fuel price risks, coincidence with peak electrical demand, and the possible deployment of PV at the point of use. Given the relatively high cost of PV, however, a key goal of these policies is to encourage cost reductions over time. Therefore, as policy incentives have become more significant and as PV deployment has accelerated, so too has the desire to track the installed cost of PV systems over …
Date: December 13, 2010
Creator: Barbose, Galen; Darghouth, Naim & Wiser, Ryan
Object Type: Report
System: The UNT Digital Library
Quark mass variation constraints from Big Bang nucleosynthesis (open access)

Quark mass variation constraints from Big Bang nucleosynthesis

We study the impact on the primordial abundances of light elements created of a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a model-independent way we use lattice QCD data and an hierarchy of effective field theories. We find that the measured {sup 4}He abundances put a bound of {delta}-1% {approx}< m{sub q}/m{sub 1} {approx}< 0.7%. The effect of quark mass variations on the deuterium abundances can be largely compensated by changes of the baryon-to-photon ratio {eta}. Including the bounds on the variation of {eta} coming from WMAP results and some additional assumptions narrows the range of allowed values of {delta}m{sub q}/m{sub q} somewhat.
Date: December 13, 2010
Creator: Bedaque, P.; Luu, T. & Platter, L.
Object Type: Article
System: The UNT Digital Library
Innovations in Nuclear Infrastructure and Education (open access)

Innovations in Nuclear Infrastructure and Education

The decision to implement the Innovation in Nuclear Infrastructure and Engineering Program (INIE) was an important first step towards ensuring that the United States preserves its worldwide leadership role in the field of nuclear science and engineering. Prior to INIE, university nuclear science and engineering programs were waning, undergraduate student enrollment was down, university research reactors were being shut down, while others faced the real possibility of closure. For too long, cutting edge research in the areas of nuclear medicine, neutron scattering, radiochemistry, and advanced materials was undervalued and therefore underfunded. The INIE program corrected this lapse in focus and direction and started the process of drawing a new blueprint with positive goals and objectives that supports existing as well the next generation of educators, students and researchers.
Date: December 13, 2010
Creator: Bernard, John
Object Type: Report
System: The UNT Digital Library
Earth's Magnetic Field Measurements for the LCLS Undulators (open access)

Earth's Magnetic Field Measurements for the LCLS Undulators

Measurements of the earth's magnetic field at several locations at SLAC were conducted to determine the possible field error contribution from tuning the undulators in a location with a different magnetic field than that which will be found in the undulator hall. An average difference of 0.08 {+-} 0.04 Gauss has been measured between the downward earth's field components in the test facility and SLAC tunnel locations.
Date: December 13, 2010
Creator: Hacker, Kirsten
Object Type: Report
System: The UNT Digital Library
Triggering for Magnetic Field Measurements of the LCLS Undulators (open access)

Triggering for Magnetic Field Measurements of the LCLS Undulators

A triggering system for magnetic field measurements of the LCLS undulators has been built with a National Instruments PXI-1002 and a Xylinx FPGA board. The system generates single triggers at specified positions, regardless of encoder sensor jitter about a linear scale.
Date: December 13, 2010
Creator: Hacker, Kirsten
Object Type: Report
System: The UNT Digital Library
Environmental Reactivity of Solid-State Hydrogen Systems: Fundamental Testing and Evaluation (open access)

Environmental Reactivity of Solid-State Hydrogen Systems: Fundamental Testing and Evaluation

In order to enable the commercial acceptance of solid state hydrogen storage materials and systems it is important to understand the risks associated with the environmental exposure of various materials. In some instances, these materials are sensitive to the environment surrounding the material and the behavior is unique and independent to each material. The development of testing procedures to evaluate a material's behavior with different environmental exposures is a critical need. In some cases material modifications may be needed in order to reduce the risk of environmental exposure. We have redesigned two standardized UN tests for clarity and exactness; the burn rate and self-heating tests. The results of these and other UN tests are shown for ammonia borane, NH{sub 3}BH{sub 3}, and alane, AlH{sub 3}. The burn rate test showed a strong dependence on the preparation method of aluminum hydride as the particle size and trace amounts of solvent greatly influence the test results. The self-heating test for ammonia borane showed a failed test as low as 70 C in a modified cylindrical form. Finally, gas phase calorimetry was performed and resulted in an exothermic behavior within an air and 30%RH environment.
Date: December 13, 2010
Creator: James, C.; Cortes-Concepcion, J.; Anton, D. & Tamburello, D.
Object Type: Article
System: The UNT Digital Library
Iran Sanctions (open access)

Iran Sanctions

This report focuses on the United States' relationship with Iran and how the Obama Administration is handling prior administration's economic sanctions against Iran. The Obama Administration's policy approach toward Iran has contrasted with the Bush Administration's by attempting to couple the imposition of sanctions to an active and direct U.S. effort to negotiate with Iran on the nuclear issue. That approach was not initially altered because of the Iranian dispute over its June 12, 2009, elections. However, with subsequent negotiations yielding no firm Iranian agreement to compromise, since early 2010 the Administration has focused on achieving the imposition of additional U.N., U.S., and allied country sanctions whose cumulative effect would be to compel it to accept a nuclear bargain.
Date: December 13, 2010
Creator: Katzman, Kenneth
Object Type: Report
System: The UNT Digital Library
Tests of Coordinate Transfer from Magnetic to Mechanical Reference for LCLS Undulator Fiducialization (open access)

Tests of Coordinate Transfer from Magnetic to Mechanical Reference for LCLS Undulator Fiducialization

Fiducialization of the LCLS undulators will be based on magnetic measurements by Hall probe. Pointed magnets, proposed by I.Vasserman for quadrupole lens fiducialization will be used as an intermediate reference. A prototype of the pointed magnet fixture has been made and tested. In this note we will describe a procedure for measuring the position of the center of the Hall probe sensitive area with respect to the undulator fiducial marks. The pointed magnet calibration procedure, a two-point algorithm for locating the magnetic center of the fixture, and test results are presented.
Date: December 13, 2010
Creator: Levashov, Yu.
Object Type: Report
System: The UNT Digital Library
Thermal Degradation Behavior of Siloxane Elastomer Impregnated Carbon Nanotube Areogel Networks (open access)

Thermal Degradation Behavior of Siloxane Elastomer Impregnated Carbon Nanotube Areogel Networks

A novel class of nanoporous graphitic carbon foams has been synthesized. Unprecedented properties - electrically conductive, thermally stable (> 1000 C), and mechanically robust. Improved transport properties (DWNT-CA, SWNT-CA) - greater than 100% enhancement in thermal conductivity, 100-400% improvement in electrical conductivity. Rich mechanical deformation behavior (SWNT-CA) - stiff ({approx}100% improvement of elastic modulus), energy dissipation, fracture toughness, and fatigue behavior. Implications for energy-related technologies - hydrogen storage, fusion and fission energy, catalysis, electrochemical energy storage, and composites with foam scaffolds.
Date: December 13, 2010
Creator: Lewicki, J P & Worsley, M A
Object Type: Article
System: The UNT Digital Library
RF Design of the LCLS Gun (open access)

RF Design of the LCLS Gun

Final dimensions for the LCLS RF gun are described. This gun, referred to as the LCLS gun, is a modified version of the UCLA/BNL/SLAC 1.6 cell S-Band RF gun [1], referred to as the prototype gun. The changes include a larger mode separation (15 MHz for the LCLS gun vs. 3.5 MHz for the prototype gun), a larger radius at the iris between the 2 cells, a reduced surface field on the curvature of the iris between the two cells, Z power coupling, increased cooling channels for operation at 120 Hz, dual rf feed, deformation tuning of the full cell, and field probes in both cells. Temporal shaping of the klystron pulse, to reduce the average power dissipated in the gun, has also been adopted. By increasing the mode separation, the amplitude of the 0-mode electric field on the cathode decreases from 10% of the peak on axis field for the prototype gun to less than 3% for the LCLS gun for the steady state fields. Beam performance is improved as shown by the PARMELA simulations. The gun should be designed to accept a future load lock system. Modifications follow the recommendations of our RF review committee [2]. Files and …
Date: December 13, 2010
Creator: Limborg-Deprey, C
Object Type: Report
System: The UNT Digital Library
Wakefield Calculations for Radiation Stopper 1 (RST1) (open access)

Wakefield Calculations for Radiation Stopper 1 (RST1)

The main result of this note is that no wakefield mitigation is required for the Radiation Stopper (RST1) in the LCLS injector. The RST1 geometry is not symmetric in the vertical direction, and we derive a slight modification to the diffraction model wake for a cylindrically symmetric (2D) cavity that can be used for this problem. Performing a full 3D MAFIA calculation for the nominal 1 mm (rms) long bunch, we show that the modified diffraction model well describes the wakefields generated in RST1. The results imply an on-axis emittance growth of 0.0075%, well below the 0.5% tolerance threshold. To reach the 0.5% threshold the beam would need to be mis-steered by a large amount - 7 mm - from the axis. One reason that the effect is small is that the beta functions at the RST1 are small.
Date: December 13, 2010
Creator: Limborg-Deprey, C.
Object Type: Report
System: The UNT Digital Library
Wakefield Computations for the Injector (Part I) (open access)

Wakefield Computations for the Injector (Part I)

In this document, we report on basic wakefield computations used to establish the impedance budget for the LCLS injector. Systematic comparisons between analytic formulae and results from ABCI are done. Finally, a comparison between 2D and 3D wakefield calculations are given for a cross. The three parts of the document are presented as follows: (1) ABCI computations for a few structures (Flange, Bellows...); (2) Comparison analytic with ABCI runs; and (3) Comparison Cross and Cavity using MAFIA.
Date: December 13, 2010
Creator: Limborg-Deprey, C.
Object Type: Report
System: The UNT Digital Library
Location of Maximum Credible Beam Losses in LCLS Injector (open access)

Location of Maximum Credible Beam Losses in LCLS Injector

The memo describes the maximum credible beam the LCLS injector can produce and lose at various locations along the beamline. The estimation procedure is based upon three previous reports [1, 2, 3]. While specific numbers have been updated to accurately reflect the present design parameters, the conclusions are very similar to those given in Ref 1. The source of the maximum credible beam results from the explosive electron emission from the photocathode if the drive laser intensity exceeds the threshold for plasma production. In this event, the gun's RF field can extract a large number of electrons from this plasma which are accelerated out of the gun and into the beamline. This electron emission persists until it has depleted the gun of all its energy. Hence the number of electrons emitted per pulse is limited by the amount of stored RF energy in the gun. It needs to be emphasized that this type of emission is highly undesirable, as it causes permanent damage to the cathode.
Date: December 13, 2010
Creator: Mao, Stan
Object Type: Report
System: The UNT Digital Library
Piracy: A Legal Definition (open access)

Piracy: A Legal Definition

This report first examines the historical development of the offense of piracy, as defined by Congress and codified in the United States Code. The focus then turns to how contemporary international agreements define piracy. Finally, the report highlights developments in two trials involving charges of piracy in the federal district court in Norfolk, VA, United States v. Said and United States v. Hasan, specifically focusing on how the courts interpreted the definition of piracy under 18 U.S.C. § 1651.
Date: December 13, 2010
Creator: Mason, R. Chuck
Object Type: Report
System: The UNT Digital Library
Actual Farm Bill Spending and Cost Estimates (open access)

Actual Farm Bill Spending and Cost Estimates

This report discusses the budget for the 2008 Farm Bill, and its reauthorization. Moreover, the report discusses the increasing level of demand for fiscal constraint and the current large budget deficits.
Date: December 13, 2010
Creator: Monke, Jim & Johnson, Renée
Object Type: Report
System: The UNT Digital Library
Emergency Communications: Broadband and the Future of 911 (open access)

Emergency Communications: Broadband and the Future of 911

This report discusses the Summary of 911 Legislation and Policy, Funding and Grants and National Broadband Plan.
Date: December 13, 2010
Creator: Moore, Linda K.
Object Type: Report
System: The UNT Digital Library
The National Ignition Facility and the Promise of Inertial Fusion Energy (open access)

The National Ignition Facility and the Promise of Inertial Fusion Energy

The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) in Livermore, CA, is now operational. The NIF is the world's most energetic laser system capable of producing 1.8 MJ and 500 TW of ultraviolet light. By concentrating the energy from its 192 extremely energetic laser beams into a mm{sup 3}-sized target, NIF can produce temperatures above 100 million K, densities of 1,000 g/cm{sup 3}, and pressures 100 billion times atmospheric pressure - conditions that have never been created in a laboratory and emulate those in planetary interiors and stellar environments. On September 29, 2010, the first integrated ignition experiment was conducted, demonstrating the successful coordination of the laser, cryogenic target system, array of diagnostics and infrastructure required for ignition demonstration. In light of this strong progress, the U.S. and international communities are examining the implication of NIF ignition for inertial fusion energy (IFE). A laser-based IFE power plant will require a repetition rate of 10-20 Hz and a laser with 10% electrical-optical efficiency, as well as further development and advances in large-scale target fabrication, target injection, and other supporting technologies. These capabilities could lead to a prototype IFE demonstration plant in the 10- to 15-year time frame. …
Date: December 13, 2010
Creator: Moses, E I
Object Type: Article
System: The UNT Digital Library
Stability in Russia's Chechnya and Other Regions of the North Caucasus: Recent Developments (open access)

Stability in Russia's Chechnya and Other Regions of the North Caucasus: Recent Developments

This report provides background information on terrorist attacks in Russia's North Caucasus that includes the formerly breakaway Chechnya and other ethnic-based regions--appeared to increase substantially in 2007-2009. The report discusses impact of the August 2008 Russia-Georgia conflict and the recent development in the Northern Caucasus.
Date: December 13, 2010
Creator: Nichol, Jim
Object Type: Report
System: The UNT Digital Library
Effect of Asymmetric Versus Symmetric Warming on Grassland Mesocosms: Final Report (open access)

Effect of Asymmetric Versus Symmetric Warming on Grassland Mesocosms: Final Report

Final Report for “Effect of Asymmetric Versus Symmetric Warming on Grassland Mesocosms”
Date: December 13, 2010
Creator: Olszyk, David M.
Object Type: Report
System: The UNT Digital Library
Keeping America's Pipelines Safe and Secure: Key Issues for Congress (open access)

Keeping America's Pipelines Safe and Secure: Key Issues for Congress

This report discusses new legislation being considered by the 111th Congress to improve the safety and security of the U.S. pipeline network. H.R. 6008 would require pipeline operators to provide immediate telephonic notice of a pipeline release to federal emergency response officials and would increase civil penalties for pipeline safety violations. S. 3824 would increase the number of federal pipeline safety inspectors, would require automatic shutoff valves for natural gas pipelines, and would mandate internal inspections of transmission pipelines, among other provisions
Date: December 13, 2010
Creator: Parfomak, Paul W.
Object Type: Report
System: The UNT Digital Library
First Measurements and Results With a Stretched Wire Test Setup (open access)

First Measurements and Results With a Stretched Wire Test Setup

The LINAC Coherent Light Source [LCLS] is a free electron laser, designed to produce high brilliant X-ray beams using Self Amplified Spontaneous Emission [SASE]. Due to the physics of SASE, the electron beam has to be held very precisely on the same trajectory as the X-ray light beam generated by the undulator magnets. To optimize the SASE output, trajectory deviations between both beams have to be minimized to a few micrometers along the entire undulator section and held stable over the time period between beam-based-alignment processes. Consequently, extremely high position stability of all magnets in the undulator section is required to operate the LCLS successfully. The knowledge of any magnet movement exceeding few micrometers during periods of several weeks is essential for efficient X-ray generation. A well known principle of monitoring transverse component positions along beam lines is the application of stretched wires, associated with suitable wire position sensors and electronics. The particular challenge at LCLS is the required wire system performance in conjunction with the length of the undulator section and the large number of monitors. Verification of system stability and resolution under real conditions is the primary goal of this test setup. A stretched wire test setup has …
Date: December 13, 2010
Creator: Peters, Franz
Object Type: Report
System: The UNT Digital Library
Aerodynamic Design Criteria for Class 8 Heavy Vehicles Trailer Base Devices to Attain Optimum Performance (open access)

Aerodynamic Design Criteria for Class 8 Heavy Vehicles Trailer Base Devices to Attain Optimum Performance

Lawrence Livermore National Laboratory (LLNL) as part of its Department of Energy (DOE), Energy Efficiency and Renewable Energy (EERE), and Vehicle Technologies Program (VTP) effort has investigated class 8 tractor-trailer aerodynamics for many years. This effort has identified many drag producing flow structures around the heavy vehicles and also has designed and tested many new active and passive drag reduction techniques and concepts for significant on the road fuel economy improvements. As part of this effort a database of experimental, computational, and conceptual design for aerodynamic drag reduction devices has been established. The objective of this report is to provide design guidance for trailer base devices to improve their aerodynamic performance. These devices are commonly referred to as boattails, base flaps, tail devices, and etc. The information provided here is based on past research and our most recent full-scale experimental investigations in collaboration with Navistar Inc. Additional supporting data from LLNL/Navistar wind tunnel, track test, and on the road test will be published soon. The trailer base devices can be identified by 4 flat panels that are attached to the rear edges of the trailer base to form a closed cavity. These devices have been engineered in many different forms …
Date: December 13, 2010
Creator: Salari, K & Ortega, J
Object Type: Report
System: The UNT Digital Library
The Genetic Information Nondiscrimination Act of 2008 and the Patient Protection and Affordable Care Act of 2010: Overview and Legal Analysis of Potential Interactions (open access)

The Genetic Information Nondiscrimination Act of 2008 and the Patient Protection and Affordable Care Act of 2010: Overview and Legal Analysis of Potential Interactions

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Date: December 13, 2010
Creator: Sarata, Amanda K.; Jones, Nancy Lee & Staman, Jennifer A.
Object Type: Report
System: The UNT Digital Library