Development of a 10 MW Sheet Beam Klystron for the ILC (open access)

Development of a 10 MW Sheet Beam Klystron for the ILC

SLAC is developing a 10 MW, 5 Hz, 1.6 ms, L-band (1.3 GHz) Sheet-Beam Klystron as a less expensive and more compact alternative to the ILC baseline Multiple-Beam Klystron. The Klystron is intended as a plug-compatible device of the same beam current and operating voltage as existing Multiple-Beam Klystrons. At this time, a beam tester has been constructed and currently is in test. The beam tester includes an intercepting cup for making beam quality measurements of the 130 A, 40-to-1 aspect ratio beam. Measurements will be made of the electrostatic beam and of the beam after transporting through a drift tube and magnetic focusing system. General theory of operation, design trade-offs, and manufacturing considerations of both the beam tester and klystron will be discussed.
Date: May 7, 2009
Creator: Sprehn, D.; Jongewaard, E.; Haase, A.; Jensen, A.; Martin, D.; /SLAC et al.
Object Type: Article
System: The UNT Digital Library
ACRF Instrumentation Status and Information April 2009 (open access)

ACRF Instrumentation Status and Information April 2009

The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Climate Research Facility instrumentation status. The report is divided into the following five sections: (1) new instrumentation in the process of being acquired and deployed, (2) field campaigns, (3) existing instrumentation and progress on improvements or upgrades, (4) proposed future instrumentation, and (5) Small Business Innovation Research instrument development.
Date: May 7, 2009
Creator: Voyles, JW
Object Type: Report
System: The UNT Digital Library
SBIR Phase I final Report (open access)

SBIR Phase I final Report

The approach that we propose here in this SBIR proposal is a modified water electrolysis cell. In conventional water electrolysis the H2O is split into electrons, protons, and oxygen gas at the anode electrode. The electrons travel through an external power source and the protons travel through an electrolyte membrane to the cathode where they recombine to form hydrogen gas. The power source requires a minimum of 1.23 V to overcome the potential difference of the electrodes for the splitting of water. In contrast in our approach proposed here, instead of splitting water we are using acetate in wastewater and bacteria to oxidize the acetate into electrons and protons at the anode surface. The microbes release the electrons to the anode and the resulting protons move to the cathode electrode through the proton exchange membrane as described above and recombine to form hydrogen gas. The advantage here is that the required potential is now on the order of 0.25 to 0.8 V, and a considerable savings in electricity is realized to produce the same amount of hydrogen while at the same time removing organic matter from wastewater streams. Significant improvements in current density needs to be made in order for …
Date: July 7, 2009
Creator: Grot, Stephen
Object Type: Report
System: The UNT Digital Library
Optics Design for FACET (open access)

Optics Design for FACET

FACET is a proposed facility at SLAC National Accelerator Laboratory. It will provide high energy, tightly focused and compressed electron and positron bunches for beam driven plasma wakefield acceleration research and other experiments. FACET will be built in the SLAC linac sector 20, where it will be separated from the LCLS located immediately downstream and will take advantage of the upstream 2 km linac for up to 23 GeV beam acceleration. FACET will also include an upgrade to linac sector 10, where a new e+ compressor chicane will be installed. The sector 20 will contain a new optics consisting of two chicanes for e+ and ebunch length compression, a final focus and an experimental line with a dump. The e+ and e- chicanes will allow the transport of e+ and ebunches together, their compression and proper positioning of e+ witness bunch behind the e- drive bunch at the plasma Interaction Point. The new optics will mostly use the existing SLAC magnets to minimize the project cost. Details of the FACET optics design and results of particle tracking simulations are presented.
Date: May 7, 2009
Creator: Nosochkov, Y.; Bane, K.; Bentson, L.; Erickson, R.; Hogan, M. J.; Li, N. et al.
Object Type: Article
System: The UNT Digital Library
Chiral Gauge Dynamics and Dynamical Supersymmetry Breaking (open access)

Chiral Gauge Dynamics and Dynamical Supersymmetry Breaking

We study the dynamics of a chiral SU(2) gauge theory with a Weyl fermion in the I = 3/2 representation and of its supersymmetric generalization. In the former, we find a new and exotic mechanism of confinement, induced by topological excitations that we refer to as magnetic quintets. The supersymmetric version was examined earlier in the context of dynamical supersymmetry breaking by Intriligator, Seiberg, and Shenker, who showed that if this gauge theory confines at the origin of moduli space, one may break supersymmetry by adding a tree level superpotential. We examine the dynamics by deforming the theory on S{sup 1} x R{sup 3}, and show that the infrared behavior of this theory is an interacting CFT at small S{sup 1}. We argue that this continues to hold at large S{sup 1}, and if so, that supersymmetry must remain unbroken. Our methods also provide the microscopic origin of various superpotentials in SQCD on S{sup 1} x R{sup 3}--which were previously obtained by using symmetry and holomorphy--and resolve a long standing interpretational puzzle concerning a flux operator discovered by Affleck, Harvey, and Witten. It is generated by a topological excitation, a 'magnetic bion', whose stability is due to fermion pair exchange …
Date: May 7, 2009
Creator: Poppitz, Erich; U., /Toronto; Unsal, Mithat & U., /SLAC /Stanford
Object Type: Article
System: The UNT Digital Library
Digitally Controlled High Availability Power Supply (open access)

Digitally Controlled High Availability Power Supply

This paper will report on the test results of a prototype 1320 watt power module for a high availability power supply. The module will allow parallel operation for N+1 redundancy with hot swap capability. The two quadrant output of each module allows pairs of modules to provide a 4 quadrant (bipolar) operation. Each module employs a novel 4 FET buck regulator arranged in a bridge configuration. Each side of the bridge alternately conducts through a small saturable ferrite that limits the reverse current in the FET body diode during turn off. This allows hard switching of the FETs with low switching losses. The module is designed with over-rated components to provide high reliability and better then 97% efficiency at full load. The modules use a Microchip DSP for control, monitoring, and fault detection. The switching FETS are driven by PWM modules in the DSP at 60 KHz. A Dual CAN bus interface provides for low cost redundant control paths. The DSP will also provide current sharing between modules, synchronized switching, and soft start up for hot swapping. The input and output of each module have low resistance FETs to allow hot swapping and isolation of faulted units.
Date: May 7, 2009
Creator: MacNair, David
Object Type: Article
System: The UNT Digital Library
Thin Silicon MEMS Contact-Stress Sensor (open access)

Thin Silicon MEMS Contact-Stress Sensor

This work offers the first, thin, MEMS contact-stress (CS) sensor capable of accurate in situ measruement of time-varying, contact-stress between two solid interfaces (e.g. in vivo cartilage contact-stress and body armor dynamic loading). This CS sensor is a silicon-based device with a load sensitive diaphragm. The diaphragm is doped to create piezoresistors arranged in a full Wheatstone bridge. The sensor is similar in performance to established silicon pressure sensors, but it is reliably produced to a thickness of 65 {micro}m. Unlike commercial devices or other research efforts, this CS sensor, including packaging, is extremely thin (< 150 {micro}m fully packaged) so that it can be unobtrusively placed between contacting structures. It is built from elastic, well-characterized materials, providing accurate and high-speed (50+ kHz) measurements over a potential embedded lifetime of decades. This work explored sensor designs for an interface load range of 0-2 MPa; however, the CS sensor has a flexible design architecture to measure a wide variety of interface load ranges.
Date: December 7, 2009
Creator: Kotovsky, J; Tooker, A & Horsley, D A
Object Type: Article
System: The UNT Digital Library
Solid Solution Phases in the Olivine-Type LiMnPO4/MnPO4 System (open access)

Solid Solution Phases in the Olivine-Type LiMnPO4/MnPO4 System

Nonstoichiometry is reported in the LiMnPO{sub 4}/MnPO{sub 4} system for the first time. As lithium is removed from crystalline LiMnPO{sub 4} by chemical or electrochemical methods, the resulting two phase mixture consists of stoichiometric LiMnPO{sub 4} and a delithiated phase, Li{sub y}MnPO{sub 4}, whose lattice parameters depend upon the global extent of delithiation and on the crystalline domain size of the delithiated phase. This behavior is reproduced during electrochemical insertion of lithium. Again, no evidence for nonstoichiometry was found in the vicinity of LiMnPO{sub 4}. Attempts to create single phase solid solutions by heating mixtures of the two phases failed due to the thermal instability of Li{sub y}MnPO{sub 4}.
Date: April 7, 2009
Creator: Chen, Guoying & Richardson, Thomas J.
Object Type: Article
System: The UNT Digital Library
Design and Operation of a tunable MeV-level Compton-scattering-based (gamma-ray) source (open access)

Design and Operation of a tunable MeV-level Compton-scattering-based (gamma-ray) source

A mono-energetic gamma-ray (MEGa-ray) source based on Compton-scattering, targeting nuclear physics applications such as nuclear resonance fluorescence, has been constructed and commissioned at Lawrence Livermore National Laboratory. In this paper, the overall architecture of the system, as well as some of the critical design decisions made in the development of the source, are discussed. The performances of the two laser systems (one for electron production, one for scattering), the electron photoinjector, and the linear accelerator are also detailed, and initial {gamma}-ray results are presented.
Date: July 7, 2009
Creator: Gibson, D. J.; Albert, F.; Anderson, S. G.; Betts, S. M.; Messerly, M. J.; Phan, H. H. et al.
Object Type: Article
System: The UNT Digital Library
Binary pseudo-random gratings and arrays for calibration of the modulation transfer function of surface profilometers: recent developments (open access)

Binary pseudo-random gratings and arrays for calibration of the modulation transfer function of surface profilometers: recent developments

The major problem of measurement of a power spectral density (PSD) distribution of the surface heights with surface profilometers arises due to the unknown Modulation Transfer Function (MTF) of the instruments. The MTF tends to distort the PSD at higher spatial frequencies. It has been suggested [Proc. SPIE 7077-7, (2007), Opt. Eng. 47 (7), 073602-1-5 (2008)] that the instrumental MTF of a surface profiler can be precisely measured using standard test surfaces based on binary pseudo-random (BPR) patterns. In the cited work, a one dimensional (1D) realization of the suggested method based on use of BPR gratings has been demonstrated. Here, we present recent achievements made in fabricating and using two-dimensional (2D) BPR arrays that allow for a direct 2D calibration of the instrumental MTF. The 2D BPRAs were used as standard test surfaces for 2D MTF calibration of the MicromapTM-570 interferometric microscope with all available objectives. The effects of fabrication imperfections on the efficiency of calibration are also discussed.
Date: July 7, 2009
Creator: Barber, Samuel K.; Soldate, Paul; Anderson, Erik H.; Cambie, Rossana; Marchesini, Stefano; McKinney, Wanye R. et al.
Object Type: Article
System: The UNT Digital Library
Thermal Instability of Olivine-Type LiMnP04 Cathodes (open access)

Thermal Instability of Olivine-Type LiMnP04 Cathodes

The remarkable thermal stability of LiFePO{sub 4} and its charged counterpart, FePO{sub 4}, have been instrumental in its commercialization as a lithium ion battery cathode material. Despite the similarity in composition and structure, and despite the high thermal stability of the parent compound, LiMnPO{sub 4}, we find that the delithiated phase Li{sub y}MnPO{sub 4}, (which contains a small amount of residual lithium), is relatively unstable and reactive toward a lithium ion electrolyte. The onset temperature for heat evolution in the presence of 1M LiPF{sub 6} in 1:1 ethylene carbonate/propylene carbonate is around 150 C, and the total evolved heat is 884 J/g, comparable to that produced under similar conditions by charged LiCoO{sub 2} electrodes.
Date: July 7, 2009
Creator: Chen, Guoying & Richardson, Thomas J.
Object Type: Article
System: The UNT Digital Library
BaBrI:Eu2 + , a new bright scintillator (open access)

BaBrI:Eu2 + , a new bright scintillator

The scintillation properties of BaBrI:Eu2+ are reported. Crystals were produced by the vertical Bridgman technique in a sealed quartz ampoule. Excellent scintillation properties were measured. A light yield of 81,0007 +- 3000 photons per MeV (ph/MeV) of absorbed gamma-ray energy was measured. An energy resolution (FWHM over peak position) of 4.870.5percent was observed for the 662keV full absorption peak. Pulsed X-ray luminescence measurements show two exponential decay components of 297 and 482 ns with a contribution to the total light output of 23percent and 77percent, respectively. Under X-ray and UV excitation, the emission corresponds to a broadband center at 413 nm. These initial values make BaBrI:Eu2+ one of the brightest and the fastest known Eu2+ doped scintillators.
Date: November 7, 2009
Creator: Bourret-Courchesne, E.D.; Bizarri, G.; Hanrahan, S.M.; Gundiah, G.; Yan, Z. & Derenzo, S.E.
Object Type: Article
System: The UNT Digital Library
Kinase Expression and Chromosomal Rearrangements in Papillary Thyroid Cancer Tissues: Investigations at the Molecular and Microscopic Levels (open access)

Kinase Expression and Chromosomal Rearrangements in Papillary Thyroid Cancer Tissues: Investigations at the Molecular and Microscopic Levels

Structural chromosome aberrations are known hallmarks of many solid tumors. In the papillary form of thyroid cancer (PTC), for example, activation of the receptor tyrosine kinase (RTK) genes, ret or the neurotrophic tyrosine kinase receptor type I (NTRK1) by intra- or interchromosomal rearrangements have been suggested as a cause of the disease. The 1986 accident at the nuclear power plant in Chernobyl, USSR, led to the uncontrolled release of high levels of radioisotopes. Ten years later, the incidence of childhood papillary thyroid cancer (chPTC) near Chernobyl had risen by two orders of magnitude. Tumors removed from some of these patients showed aberrant expression of the ret RTK gene due to a ret/PTC1 or ret/PTC3 rearrangement involving chromosome 10. However, many cultured chPTC cells show a normal G-banded karyotype and no ret rearrangement. We hypothesize that the 'ret-negative' tumors inappropriately express a different oncogene or have lost function of a tumor suppressor as a result of chromosomal rearrangements, and decided to apply molecular and cytogenetic methods to search for potentially oncogenic chromosomal rearrangements in Chernobyl chPTC cases. Knowledge of the kind of genetic alterations may facilitate the early detection and staging of chPTC as well as provide guidance for therapeutic intervention.
Date: July 7, 2009
Creator: Weier, Heinz-Ulrich; Kwan, Johnson; Lu, Chun-Mei; Ito, Yuko; Wang, Mei; Baumgartner, Adolf et al.
Object Type: Report
System: The UNT Digital Library
The Shifting Landscape of Ratepayer-Funded Energy Efficiency in the U.S. (open access)

The Shifting Landscape of Ratepayer-Funded Energy Efficiency in the U.S.

None
Date: July 7, 2009
Creator: Barbose, G.; Goldman, C. & Schlegel, J.
Object Type: Article
System: The UNT Digital Library
A Topological Framework for the Interactive Exploration of Large Scale Turbulent Combustion (open access)

A Topological Framework for the Interactive Exploration of Large Scale Turbulent Combustion

None
Date: August 7, 2009
Creator: Bremer, Peer-Timo; Weber, Gunther; Tierny, Julien; Pascucci, Valerio; Day, Marcus & Bell, John
Object Type: Article
System: The UNT Digital Library
High pressure phase transformation in iron under fast compression (open access)

High pressure phase transformation in iron under fast compression

We present experimental results on the solid-solid, {alpha} to {epsilon} phase transformation kinetics of iron under high pressure dynamic compression. We observe kinetic features - velocity loops - similar with the ones recently reported to occur when water is frozen into its ice VII phase under comparable experimental conditions. We analyze this behavior in terms of general ideas coupling the steady sample compression with phase nucleation and growth with a pressure dependent phase interface velocity. The model is used to predict the response of iron when steadily driven across the {alpha} - {epsilon} phase boundary on very short time scales, including those envisioned to be achieved in ultra-fast laser experiments.
Date: July 7, 2009
Creator: Bastea, M; Bastea, S & Becker, R
Object Type: Article
System: The UNT Digital Library
Enemy Combatant Detainees: Habeas Corpus Challenges in Federal Court (open access)

Enemy Combatant Detainees: Habeas Corpus Challenges in Federal Court

This report provides an overview of the early judicial developments and the establishment of Combatant Status Review Tribunals (CSRTs) procedures; summarizes selected court cases related to the detentions and the use of military commissions; and discusses the Detainee Treatment Act, as amended by the Military Commissions Act of 2006 and the Military Commissions Act of 2009, analyzing its effects on detainee-related litigation in federal court. The report summarizes the Supreme Court's decision in Boumediene invalidating Congress's efforts to revoke the courts' habeas jurisdiction, and discusses some remaining issues and subsequent developments.
Date: April 7, 2009
Creator: Elsea, Jennifer K. & Garcia, Michael J.
Object Type: Report
System: The UNT Digital Library
Nanotechnology: A Policy Primer (open access)

Nanotechnology: A Policy Primer

This report provides an overview of nanotechnology, nanomanufacturing, and public understanding of and attitudes toward nanotechnology. Congress has demonstrated continuing support for nanotechnology and has directed its attention primarily to three topics that may affect the realization of this hoped for potential: federal research and development (R&D) in nanotechnology; U.S. competitiveness; and environmental, health, and safety (EHS) concerns.
Date: February 7, 2009
Creator: Sargent, John F., Jr.
Object Type: Report
System: The UNT Digital Library
Iraqi Police and Security Forces Casualties Estimates (open access)

Iraqi Police and Security Forces Casualties Estimates

This report presents various governmental and non-governmental estimates of Iraqi police and security forces fatalities. The Department of Defense (DOD) regularly updates total U.S. military deaths and wounded statistics from Operation Iraqi Freedom (OIF), as reflected in CRS Report RS21578, Iraq: U.S. Casualties, and has released the monthly pattern of Iraqi security forces deaths. For information on Iraqi civilian deaths, see CRS Report RS22537, Iraqi Civilian Deaths Estimates. Because these estimates are based on varying time periods and have been created using differing methodologies, readers should exercise caution when using them and should look on them as guideposts rather than as statements of fact.
Date: January 7, 2009
Creator: Fischer, Hannah
Object Type: Report
System: The UNT Digital Library
Israel and the Palestinians: Prospects for a Two-State Solution (open access)

Israel and the Palestinians: Prospects for a Two-State Solution

This report gives a brief overview of the Israeli-Palestinian conflict and examines recent developments, diplomatic and otherwise. The report also states two options for reaching a two-state solution and several alternative proposals for dealing with the conflict.
Date: October 7, 2009
Creator: Zanotti, Jim
Object Type: Report
System: The UNT Digital Library
The Strategic Petroleum Reserve: History, Perspectives and Issues (open access)

The Strategic Petroleum Reserve: History, Perspectives and Issues

This reports discusses the history and establishment of Strategic Petroleum Reserve (SPR), acquisition of crude oil for the SPR. It talks about the debate over the years regarding when should the SPR be used.
Date: January 7, 2009
Creator: Bamberger, Robert
Object Type: Report
System: The UNT Digital Library
Strategic Arms Control After START: Issues and Options (open access)

Strategic Arms Control After START: Issues and Options

The United States and Soviet Union signed the Strategic Arms Reduction Treaty in 1991; it entered into force in December 1994 and expired in December 2009. This report provides background information about the START Treaty and reviews the discussions about a possible successor to START. It also presents a range of alternatives that the United States and Russia might consider if they choose to follow START with a new framework for the arms control process.
Date: December 7, 2009
Creator: Woolf, Amy F.
Object Type: Report
System: The UNT Digital Library
An Overview of the Presidential Pardoning Power (open access)

An Overview of the Presidential Pardoning Power

This report provides an overview of the scope of the President's pardoning power, the legal effects of a pardon, and the procedures that have traditionally been adhered to in the consideration of requests for pardons.
Date: January 7, 2009
Creator: Burrows, Vanessa K.
Object Type: Report
System: The UNT Digital Library
Federal Government Corporations: An Overview (open access)

Federal Government Corporations: An Overview

This report provides an overview of federal government corporations, a category currently consisting of some 17 corporate agencies performing functions assigned to them in law. A government corporation, as defined in this report, is a government agency that is established by Congress to provide a market-oriented public service and required to produce revenues that meet or approximate its expenditures.
Date: January 7, 2009
Creator: Kosar, Kevin R.
Object Type: Report
System: The UNT Digital Library