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Active Damping of the E-P Instability at the Los Alamos Proton Storage Ring (open access)

Active Damping of the E-P Instability at the Los Alamos Proton Storage Ring

A prototype of an analog, transverse (vertical) feedback system for active damping of the two-stream (e-p) instability has been developed and successfully tested at the Los Alamos Proton Storage Ring (PSR). This system was able to improve the instability threshold by approximately 30% (as measured by the change in RF buncher voltage at instability threshold). The feedback system configuration, setup procedures, and optimization of performance are described. Results of several experimental tests of system performance are presented including observations of instability threshold improvement and grow-damp experiments, which yield estimates of instability growth and damping rates. A major effort was undertaken to identify and study several factors limiting system performance. Evidence obtained from these tests suggests that performance of the prototype was limited by higher instability growth rates arising from beam leakage into the gap at lower RF buncher voltage and the onset of instability in the horizontal plane, which had no feedback.
Date: March 17, 2008
Creator: Macek, R. J.; Assadi, S.; Byrd, J. M.; Deibele, C. E.; Henderson, S. D.; Lee, S. Y. et al.
Object Type: Article
System: The UNT Digital Library
The Altus Times (Altus, Okla.), Vol. 109, No. 247, Ed. 1 Monday, March 17, 2008 (open access)

The Altus Times (Altus, Okla.), Vol. 109, No. 247, Ed. 1 Monday, March 17, 2008

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date: March 17, 2008
Creator: Bush, Michael
Object Type: Newspaper
System: The Gateway to Oklahoma History
The Baytown Sun (Baytown, Tex.), Vol. 88, No. 77, Ed. 1 Monday, March 17, 2008 (open access)

The Baytown Sun (Baytown, Tex.), Vol. 88, No. 77, Ed. 1 Monday, March 17, 2008

Daily newspaper from Baytown, Texas that includes local, state, and national news along with advertising.
Date: March 17, 2008
Creator: Clements, Clifford E.
Object Type: Newspaper
System: The Portal to Texas History
Beam Dynamics Studies for the SPARC Project (open access)

Beam Dynamics Studies for the SPARC Project

The aim of the SPARC project, is to promote an R&D activity oriented to the development of a high brightness photoinjector to drive SASE-FEL experiments. We discuss in this paper the status of the beam dynamics simulation activities.
Date: March 17, 2008
Creator: Ferrario, M.; Biagini, Maria E.; Boscolo, M.; Fusco, V.; Guiducci, S.; Migliorati, M. et al.
Object Type: Article
System: The UNT Digital Library
A CCD Camera with Electron Decelerator for Intermediate Voltage Electron Microscopy (open access)

A CCD Camera with Electron Decelerator for Intermediate Voltage Electron Microscopy

Electron microscopists are increasingly turning to Intermediate Voltage Electron Microscopes (IVEMs) operating at 300 - 400 kV for a wide range of studies. They are also increasingly taking advantage of slow-scan charge coupled device (CCD) cameras, which have become widely used on electron microscopes. Under some conditions CCDs provide an improvement in data quality over photographic film, as well as the many advantages of direct digital readout. However, CCD performance is seriously degraded on IVEMs compared to the more conventional 100 kV microscopes. In order to increase the efficiency and quality of data recording on IVEMs, we have developed a CCD camera system in which the electrons are decelerated to below 100 kV before impacting the camera, resulting in greatly improved performance in both signal quality and resolution compared to other CCDs used in electron microscopy. These improvements will allow high-quality image and diffraction data to be collected directly with the CCD, enabling improvements in data collection for applications including high-resolution electron crystallography, single-particle reconstruction of protein structures, tomographic studies of cell ultrastructure and remote microscope operation. This approach will enable us to use even larger format CCD chips that are being developed with smaller pixels.
Date: March 17, 2008
Creator: Downing, Kenneth H; Downing, Kenneth H. & Mooney, Paul E.
Object Type: Article
System: The UNT Digital Library
China-U.S. Relations: Current Issues and Implications for U.S. Policy (open access)

China-U.S. Relations: Current Issues and Implications for U.S. Policy

This report mainly focuses on Current Issues and Implications for U.S. Policy of China-U.S. Relations.U.S relations with China remarkably smooth from 2001-2004 have shown signs of becoming somewhat more problematic again since 2005 as some U.S policymakers.
Date: March 17, 2008
Creator: Dumbaugh, Kerry
Object Type: Report
System: The UNT Digital Library
Clean Water Act: A Summary of the Law (open access)

Clean Water Act: A Summary of the Law

This report presents a summary of the law, describing the essence of the statute without discussing its implementation. Other CRS products do discuss implementation, including CRS Report RL33800, Water Quality Issues in the 110th Congress: Oversight and Implementation, and numerous products cited in that report.
Date: March 17, 2008
Creator: Copeland, Claudia
Object Type: Report
System: The UNT Digital Library
Commerce, Justice, Science, and Related Agencies: FY2008 Appropriations (open access)

Commerce, Justice, Science, and Related Agencies: FY2008 Appropriations

This report is a guide to the regular appropriations bills that Congress consider each year. It lists the key CRS staff relevant to the issues covered and related CRS products.
Date: March 17, 2008
Creator: Krouse, William J.; Murphy, Edward V. & Villarreal, M. Angeles
Object Type: Report
System: The UNT Digital Library
Constitutionality of Applying the FCC’s Indecency Restriction to Cable Television (open access)

Constitutionality of Applying the FCC’s Indecency Restriction to Cable Television

This report examines whether such as extension would violate the First Amendment's guarantee of freedom of speech.
Date: March 17, 2008
Creator: Cohen, Henry
Object Type: Report
System: The UNT Digital Library
Coupling Correction and Beam Dynamics at Ultralow Vertical Emittance in the ALS (open access)

Coupling Correction and Beam Dynamics at Ultralow Vertical Emittance in the ALS

For synchrotron light sources and for damping rings of linear colliders it is important to be able to minimize the vertical emittance and to correct the spurious vertical dispersion. This allows one to maximize the brightness and/or the luminosity. A commonly used tool to measure the skew error distribution is the analysis of orbit response matrices using codes like LOCO. Using the new Matlab version of LOCO and 18 newly installed power supplies for individual skew quadrupoles at the ALS the emittance ratio could be reduced below 0.1% at 1.9 GeV yielding a vertical emittance of about 5 pm. At those very low emittances, additional effects like intra beam scattering become more important, potentially limiting the minimum emittance for machine like the damping rings of linear colliders.
Date: March 17, 2008
Creator: Steier, Christoph; Robin, D.; Wolski, A.; Portmann, G.; Safranek, J. & /LBL, Berkeley /SLAC
Object Type: Article
System: The UNT Digital Library
DESIGN OF AN OPTICAL DIFFERACTION RADIATION BEAM SIZE MONITOR AT SLAC FETB (open access)

DESIGN OF AN OPTICAL DIFFERACTION RADIATION BEAM SIZE MONITOR AT SLAC FETB

We design a single bunch transverse beam size monitor which will be tested to measure the 28.5 GeV electron/positron beam at the SLAC FFTB beam line. The beam size monitor uses the CCD images of the interference pattern of the optical diffraction radiation from two slit edges which are placed close to the beam path. In this method, destruction of the accelerated electron/positron beam bunches due to the beam size monitoring is negligible, which is vital to the operation of the Linear Collider project.
Date: March 17, 2008
Creator: Fukui, Y.; Cline, D.; Zhou, F.; Tobiyama, M.; Urakawa, J.; Bolton, P. R. et al.
Object Type: Article
System: The UNT Digital Library
Digitral Down Conversion Technology for Tevatron Beam Line Tuner at FNAL (open access)

Digitral Down Conversion Technology for Tevatron Beam Line Tuner at FNAL

Fermilab is presently in Run II collider operations and is developing instrumentation to improve luminosity. Improving the orbit matching between accelerator components using a Beam Line Tuner (BLT) can improve the luminosity. Digital Down Conversion (DDC) has been proposed as a method for making more accurate beam position measurements. Fermilab has implemented a BLT system using a DDC technique to measure orbit oscillations during injections from the Main Injector to the Tevatron. The output of a fast ADC is downconverted and filtered in software. The system measures the x and y positions, the intensity, and the time of arrival for each proton or antiproton bunch, on a turn-by-turn basis, during the first 1024 turns immediately following injection. We present results showing position, intensity, and time of arrival for both injected and coasting beam. Initial results indicate a position resolution of {approx}20 to 40 microns and a phase resolution of {approx}25 ps.
Date: March 17, 2008
Creator: Schappert, W.; Lorman, E.; Scarpine, V.; Ross, M.C.; Sebek, J.; Straumann, T. et al.
Object Type: Article
System: The UNT Digital Library

Doctoral Recital: 2008-03-17 - Jeremy Wirths, conductor

Recital presented at the UNT College of Music Recital Hall in partial fulfillment of the Doctor of Musical Arts (DMA) degree.
Date: March 17, 2008
Creator: Wirths, Jeremy
Object Type: Sound
System: The UNT Digital Library
Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2007 Annual Report. (open access)

Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2007 Annual Report.

This document is the first annual report for the study titled 'Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta in the Lower Columbia River'. Hereafter, we refer to this research as the Tidal Freshwater Monitoring (TFM) Study. The study is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The project is performed under the auspices of the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program. The goal of the 2007-2009 Tidal Freshwater Monitoring Study is to answer the following questions: In what types of habitats within the tidal freshwater area of the lower Columbia River and estuary (LCRE; Figure 1) are yearling and subyearling salmonids found, when are they present, and under what environmental conditions?1 And, what is the ecological importance2 of shallow (0-5 m) tidal freshwater habitats to the recovery of Upper Columbia River spring Chinook salmon and steelhead and Snake River fall Chinook salmon? Research in …
Date: March 17, 2008
Creator: Sobocinski, Kathryn; Johnson, Gary & Sather, Nichole
Object Type: Report
System: The UNT Digital Library
Electron Cloud Generation and Trapping in a Quadrupole Magnet at the Los Alamos Proton Storage Ring (open access)

Electron Cloud Generation and Trapping in a Quadrupole Magnet at the Los Alamos Proton Storage Ring

Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the 'prompt' electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the 'swept' electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100 {micro}s. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the …
Date: March 17, 2008
Creator: Macek, Robert J.; Browman, Andrew A.; Ledford, John E.; Borden, Michael J.; O'Hara, James F.; McCrady, Rodney C. et al.
Object Type: Article
System: The UNT Digital Library
Electron Cloud Mitigation in the Spallation Neutron Source Ring (open access)

Electron Cloud Mitigation in the Spallation Neutron Source Ring

The Spallation Neutron Source (SNS) accumulator ring is designed to accumulate, via H{sup -} injection, protons of 2 MW beam power at 1 GeV kinetic energy at a repetition rate of 60 Hz [1]. At such beam intensity, electron-cloud is expected to be one of the intensity-limiting mechanisms that complicate ring operations. This paper summarizes mitigation strategy adopted in the design, both in suppressing electron-cloud formation and in enhancing Landau damping, including tapered magnetic field and monitoring system for the collection of stripped electrons at injection, TiN coated beam chamber for suppression of the secondary yield, clearing electrodes dedicated for the injection region and parasitic on BPMs around the ring, solenoid windings in the collimation region, and planning of vacuum systems for beam scrubbing upon operation.
Date: March 17, 2008
Creator: Wei, J.; Blaskiewicz, Michael; Brodowski, J.; Cameron, P.; Davino, Daniele; Fedotov, A. et al.
Object Type: Article
System: The UNT Digital Library
The Executive Office of the President: An Historical Overview (open access)

The Executive Office of the President: An Historical Overview

This report reviews the particular circumstances of the creation pf, and underlying authority for, the Executive Office of the President, and provides profiles of the entities that have been, and still are, located within that enclave.
Date: March 17, 2008
Creator: Reylea, Harold C.
Object Type: Report
System: The UNT Digital Library
The Express-Star (Chickasha, Okla.), Ed. 1 Monday, March 17, 2008 (open access)

The Express-Star (Chickasha, Okla.), Ed. 1 Monday, March 17, 2008

Daily newspaper from Chickasha, Oklahoma that includes local, state, and national news along with advertising.
Date: March 17, 2008
Creator: Wilson, Chris
Object Type: Newspaper
System: The Gateway to Oklahoma History
The FCC’s Broadcast Media Ownership Rules (open access)

The FCC’s Broadcast Media Ownership Rules

This report provides information about The FCC’s Broadcast Media Ownership Rules which is intended to foster the three long-standing goals of U.S media policy-competition, localism, and diversity of voices.
Date: March 17, 2008
Creator: Goldfarb, Charles B.
Object Type: Report
System: The UNT Digital Library
Freedom of Speech and Press: Exceptions to the First Amendment (open access)

Freedom of Speech and Press: Exceptions to the First Amendment

This report provides an overview of the major exceptions to the First Amendment.
Date: March 17, 2008
Creator: Cohen, Henry
Object Type: Report
System: The UNT Digital Library
The FY2009 Budget Request for the U.S. Department of Agriculture (open access)

The FY2009 Budget Request for the U.S. Department of Agriculture

The report discusses the U.S. Department of Agriculture (USDA) budget request for FY2009. The request includes a $76 billion in mandatory funds for food stamps, child nutrition, and farm subsidies.
Date: March 17, 2008
Creator: Monke, Jim
Object Type: Report
System: The UNT Digital Library
GAO: Government Accountability Office and General Accounting Office (open access)

GAO: Government Accountability Office and General Accounting Office

This report explains the establishment and evolution of the Government Accountability Office (GAO) and its resources. The Government Accountability Office is the largest of three agencies that provides support staff, research, review, and analysis of congress.
Date: March 17, 2008
Creator: Kaiser, Frederick M.
Object Type: Report
System: The UNT Digital Library
General Relativistic Effects in Atom Interferometry (open access)

General Relativistic Effects in Atom Interferometry

Atom interferometry is now reaching sufficient precision to motivate laboratory tests of general relativity. We begin by explaining the non-relativistic calculation of the phase shift in an atom interferometer and deriving its range of validity. From this we develop a method for calculating the phase shift in general relativity. This formalism is then used to find the relativistic effects in an atom interferometer in a weak gravitational field for application to laboratory tests of general relativity. The potentially testable relativistic effects include the non-linear three-graviton coupling, the gravity of kinetic energy, and the falling of light. We propose experiments, one currently under construction, that could provide a test of the principle of equivalence to 1 part in 10{sup 15} (300 times better than the present limit), and general relativity at the 10% level, with many potential future improvements. We also consider applications to other metrics including the Lense-Thirring effect, the expansion of the universe, and preferred frame and location effects.
Date: March 17, 2008
Creator: Dimopoulos, Savas; /Stanford U., Phys. Dept.; Graham, Peter W.; /SLAC /Stanford U., Phys. Dept.; Hogan, Jason M.; Kasevich, Mark A. et al.
Object Type: Article
System: The UNT Digital Library
Global War on Terrorism: Reported Obligations for the Department of Defense (open access)

Global War on Terrorism: Reported Obligations for the Department of Defense

Correspondence issued by the Government Accountability Office with an abstract that begins "Since 2001, Congress has provided the Department of Defense (DOD) with hundreds of billions of dollars in supplemental and annual appropriations for military operations in support of the Global War on Terrorism (GWOT). DOD's reported annual obligations for GWOT have shown a steady increase from about $0.2 billion in fiscal year 2001 to about $139.8 billion in fiscal year 2007. To continue GWOT operations, the President requested $189.3 billion in appropriations for DOD in fiscal year 2008. Through December 2007, Congress has provided DOD with about $86.8 billion of this request, including $16.8 billion for Mine Resistant Ambush Protected vehicles. As of February 2008, Congress has not taken action on the remaining $102.5 billion. The United States' commitments to GWOT will likely involve the continued investment of significant resources, requiring decision makers to consider difficult trade-offs as the nation faces an increasing long-range fiscal challenge. The magnitude of future costs will depend on several direct and indirect cost variables and, in some cases, decisions that have not yet been made. DOD's future costs will likely be affected by the pace and duration of operations, the types of facilities …
Date: March 17, 2008
Creator: United States. Government Accountability Office.
Object Type: Text
System: The UNT Digital Library