Optimization of the LCLS Single Pulse Shutter (open access)

Optimization of the LCLS Single Pulse Shutter

A mechanical shutter which operates on demand is used to isolate a single pulse from a 120 Hz X-ray source. This is accomplished with a mechanical shutter which is triggered on demand with frequencies ranging from 0 to 10 Hz. The single pulse shutter is an iron blade that oscillates on a pivot in response to a force generated by a pair of pulsed electromagnets (current driven teeter-totter). To isolate an individual pulse from the X-ray beam, the motion of the mechanical shutter should be synchronized in such a way that it allows a single pulse to pass through the aperture and blocks the other incoming pulses. Two consecutive pulses are only {approx} 8 ms apart and the shutter is required to complete one full cycle such that no two pulses pass through the opening. Also the opening of the shutter blade needs to be at least 4 mm so that a 1 mm diameter rms Gaussian beam can pass through without modulation. However, the 4 mm opening is difficult to obtain due to blade rebound and oscillation of the blade after colliding with the electromagnet. The purpose of this project is to minimize and/or totally eliminate the rebound of …
Date: August 25, 2010
Creator: Adera, Solomon & /Georgia Tech., Atlanta /SLAC
Object Type: Report
System: The UNT Digital Library
Assistance to States on Electric Industry Issues (open access)

Assistance to States on Electric Industry Issues

This project seeks to educate state policymakers through a coordinated approach involving state legislatures, regulators, energy officials, and governors’ staffs. NCSL’s activities in this project focus on educating state legislators. Major components of this proposal include technical assistance to state legislatures, briefing papers, coordination with the National Council on Electricity Policy, information assistance, coordination and outreach, meetings, and a set of transmission-related activities.
Date: October 25, 2010
Creator: Andersen, Glen
Object Type: Report
System: The UNT Digital Library
The European Parliament (open access)

The European Parliament

This report discusses the construction and history of the European Parliament (EP), its role in functions of the EU as well as internationally, various international supports and criticisms of the EP, and the EP's ties with the U.S. Congress.
Date: February 25, 2010
Creator: Archick, Kristin & Mix, Derek E.
Object Type: Report
System: The UNT Digital Library
The European Union: Questions and Answers (open access)

The European Union: Questions and Answers

This report provides a summary overview of issues regarding the relationship between the United States and the EU, many of which may be of interest to the second session of the 111th Congress. The global financial crisis and recession has challenged both sides to forge a common response. The United States and EU have a number of lingering trade disputes, but have led the push to liberalize world trade, and have sought to reduce non-tariff and regulatory barriers in the transatlantic marketplace.
Date: February 25, 2010
Creator: Archick, Kristin & Mix, Derek E.
Object Type: Report
System: The UNT Digital Library
The European Union: Questions and Answers (open access)

The European Union: Questions and Answers

This report provides a brief overview of the European Union (EU), an economic and political partnership between 27 sovereign member states. The report describes the formation of the EU, the three main institutions of the EU, and the EU's relationship with the United States.
Date: August 25, 2010
Creator: Archick, Kristin & Mix, Derek E.
Object Type: Report
System: The UNT Digital Library
Higher-Twist Contributions to Large Transverse Momentum Hadron Production in hadronic collisions (open access)

Higher-Twist Contributions to Large Transverse Momentum Hadron Production in hadronic collisions

The scaling behavior of large-p{sub {perpendicular}} hadron production in hadronic collisions is investigated. A significant deviation from the NLO QCD predictions is reported, especially at high values of x{sub {perpendicular}} = 2p{sub {perpendicular}}/{radical}s. In contrast, the prompt photon and jet production data prove in agreement with leading-twist expectations. These results are interpreted as coming from a non-negligible contribution of higher-twist processes, where the hadron is produced directly in the hard subprocess. Predictions for scaling exponents at RHIC are successfully compared to PHENIX preliminary measurements. We suggest to trigger on isolated large-p{sub {perpendicular}} hadron production to enhance higher-twist processes, and point that the use of isolated hadrons as a signal for new physics at colliders can be affected by the presence of direct hadron production processes.
Date: August 25, 2010
Creator: Arleo, Francois; /Annecy, LAPTH; Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; Hwang, Dae Sung; U., /Sejong et al.
Object Type: Article
System: The UNT Digital Library
The Market Structure of the Health Insurance Industry (open access)

The Market Structure of the Health Insurance Industry

This report discusses whether or not the current health insurance market structure hinders the U.S. health system's ability to reach the policy goals of expanding health insurance coverage and containing health care costs. It also describes the forces that have shaped the health insurance industry, including its historical evolution, characteristics of health care and health insurance, determinants of supply and demand for health insurance, and the nature of competition among health insurers.
Date: May 25, 2010
Creator: Austin, D. Andrew & Hungerford, Thomas L.
Object Type: Report
System: The UNT Digital Library
Exploratory Experimentation and Computation (open access)

Exploratory Experimentation and Computation

We believe the mathematical research community is facing a great challenge to re-evaluate the role of proof in light of recent developments. On one hand, the growing power of current computer systems, of modern mathematical computing packages, and of the growing capacity to data-mine on the Internet, has provided marvelous resources to the research mathematician. On the other hand, the enormous complexity of many modern capstone results such as the Poincare conjecture, Fermat's last theorem, and the classification of finite simple groups has raised questions as to how we can better ensure the integrity of modern mathematics. Yet as the need and prospects for inductive mathematics blossom, the requirement to ensure the role of proof is properly founded remains undiminished.
Date: February 25, 2010
Creator: Bailey, David H. & Borwein, Jonathan M.
Object Type: Report
System: The UNT Digital Library
Pep-X Impedance and Instability Calculations (open access)

Pep-X Impedance and Instability Calculations

PEP-X, a next generation, ring-based light source is designed to run with beams of high current and low emittance. Important parameters are: energy 4.5 GeV, circumference 2.2 km, beam current 1.5 A, and horizontal and vertical emittances, 185 pm by 8 pm. In such a machine it is important that impedance driven instabilities not degrade the beam quality. In this report they study the strength of the impedance and its effects in PEP-X. For the present, lacking a detailed knowledge of the vacuum chamber shape, they create a straw man design comprising important vacuum chamber objects to be found in the ring, for which they then compute the wake functions. From the wake functions they generate an impedance budget and a pseudo-Green function wake representing the entire ring, which they, in turn, use for performing microwave instability calculations. In this report they, in addition, consider in PEP-X the transverse mode-coupling, multi-bunch transverse, and beam-ion instabilities.
Date: August 25, 2010
Creator: Bane, K. L. F.; Lee, L. -Q.; Ng, C.; Stupakov, G.; au Wang, L. & Xiao, L.
Object Type: Article
System: The UNT Digital Library
COMPARISON OF SIMULATION CODES FOR MICROWAVE INSTABILITY IN BUNCHED BEAMS (open access)

COMPARISON OF SIMULATION CODES FOR MICROWAVE INSTABILITY IN BUNCHED BEAMS

In accelerator design, there is often a need to evaluate the threshold to the (longitudinal) microwave instability for a bunched beam in an electron storage ring. Several computational tools are available that allow them, once given the wakefield representing a ring, to numerically find the threshold current and to simulate the development of the instability. In this work, they present results of coputer simulations using two codes recently developed at the SLAC National Accelerator Laboratory: a Vlasov-Fokker-Planck (VFP) solver based on an algorithm by Warnock and Ellison, and a program that find the threshold from the linearized Vlasov equation. They apply the programs to find the instability threshold for three models of ring impedances: that of a Q = 1 resonator, of shielded coherent synchrotron radiation (CSR), and of a resistive wall. The first example is wel-bheaved, but the other two are singular wakes that need special care. Note that similar numerical studies of the threshold of a Q = 1 resonantor wake have been performed by Oide and Yokova, and others. They compare the results of the two programs and discuss their respective capabilities and limitations. In this report they assume the slippage factor {eta} is always positive. They …
Date: August 25, 2010
Creator: Bane, K.L.F.; Cai, Y. & Stupakov, G.
Object Type: Article
System: The UNT Digital Library
Data Quality Objectives Supporting Radiological Air Emissions Monitoring for the PNNL Site (open access)

Data Quality Objectives Supporting Radiological Air Emissions Monitoring for the PNNL Site

This document of Data Quality Objectives (DQOs) was prepared based on the U.S. Environmental Protection Agency (EPA) Guidance on Systematic Planning Using the Data Quality Objectives Process, EPA, QA/G4, 2/2006 (EPA 2006) as well as several other published DQOs. Pacific Northwest National Laboratory (PNNL) is in the process of developing a radiological air monitoring program for the PNNL Site that is distinct from that of the nearby Hanford Site. Radiological emissions at the PNNL Site result from Physical Sciences Facility (PSF) major emissions units. A team was established to determine how the PNNL Site would meet federal regulations and address guidelines developed to monitor and estimate offsite air emissions of radioactive materials. The result is a program that monitors the impact to the public from the PNNL Site.
Date: May 25, 2010
Creator: Barnett, J. M.; Meier, Kirsten M.; Snyder, Sandra F.; Fritz, Brad G.; Poston, Ted M. & Rhoads, Kathleen
Object Type: Report
System: The UNT Digital Library
Gaussian Quadrature for Optical Design with Non-circular Pupils and Fields, and Broad Wavelength Ranges (open access)

Gaussian Quadrature for Optical Design with Non-circular Pupils and Fields, and Broad Wavelength Ranges

None
Date: June 25, 2010
Creator: Bauman, B J & Xiao, H
Object Type: Article
System: The UNT Digital Library
Characterization of High Level Waste from a Hybrid LIFE Engine for Enhanced Repository Performance (open access)

Characterization of High Level Waste from a Hybrid LIFE Engine for Enhanced Repository Performance

None
Date: August 25, 2010
Creator: Beckett, E. & Fratoni, M.
Object Type: Report
System: The UNT Digital Library
Thermometric- and Acoustic-Based Beam Power Monitor for Ultra-Bright X-Rays (open access)

Thermometric- and Acoustic-Based Beam Power Monitor for Ultra-Bright X-Rays

A design for an average beam power monitor for ultra-bright X-ray sources is proposed that makes simultaneous use of calorimetry and radiation acoustics. Radiation incident on a solid target will induce heating and ultrasonic vibrations, both of which may be measured to give a fairly precise value of the beam power. The monitor is intended for measuring ultra-bright Free-Electron Laser (FEL) X-ray beams, for which traditional monitoring technologies such as photo-diodes or scintillators are unsuitable. The monitor consists of a Boron Carbide (B{sub 4}C) target designed to absorb most of the incident beam's energy. Resistance temperature detectors (RTD) and piezoelectric actuators are mounted on the outward faces of the target to measure the temperature changes and ultrasonic vibrations induced by the incident beam. The design was tested using an optical pulsed beam (780 nm, 120 and 360 Hz) from a Ti:sapphire oscillator at several energies between 0.8 and 2.6 mJ. The RTDs measured an increase in temperature of about 10 K over a period of several minutes. The piezoelectric sensors recorded ringing acoustic oscillations at 580 {+-} 40 kHz. Most importantly, the amplitude of the acoustic signals was observed to scale linearly with beam power up to 2 mJ of …
Date: August 25, 2010
Creator: Bentsen, Gregory & /SLAC, /Rochester U.
Object Type: Report
System: The UNT Digital Library
Physical Properties of Hanford Transuranic Waste (open access)

Physical Properties of Hanford Transuranic Waste

The research described herein was undertaken to provide needed physical property descriptions of the Hanford transuranic tank sludges under conditions that might exist during retrieval, treatment, packaging and transportation for disposal. The work addressed the development of a fundamental understanding of the types of systems represented by these sludge suspensions through correlation of the macroscopic rheological properties with particle interactions occurring at the colloidal scale in the various liquid media. The results of the work have advanced existing understanding of the sedimentation and aggregation properties of complex colloidal suspensions. Bench scale models were investigated with respect to their structural, colloidal and rheological properties that should be useful for the development and optimization of techniques to process the wastes at various DOE sites.
Date: March 25, 2010
Creator: Berg, John C.
Object Type: Report
System: The UNT Digital Library
Vector Boson Jets with BlackHat and Sherpa (open access)

Vector Boson Jets with BlackHat and Sherpa

We review recent NLO QCD results for W, Z + 3-jet production at hadron colliders, computing using BlackHat and SHERPA, and including also some new results for Z + 3-jet production for the LHC at 7 TeV. We report new progress towards the NLO cross section for W + 4-jet production. In particular, we show that the virtual matrix elements produced by BlackHat are numerically stable. We also show that with an improved integrator and tree-level matrix elements from BlackHat, SHERPA produces well-behaved real-emission contributions. As an illustration, we present the real-emission contributions - including dipole-subtraction terms - to the p{sub T} distribution of the fourth jet, for a single subprocess with the maximum number of gluons.
Date: August 25, 2010
Creator: Berger, C.F.; /MIT, LNS; Bern, Z.; /UCLA; Dixon, Lance J.; /SLAC et al.
Object Type: Article
System: The UNT Digital Library
The Complete Four-Loop Four-Point Amplitude in N (open access)

The Complete Four-Loop Four-Point Amplitude in N

We present the complete four-loop four-point amplitude in N = 4 super-Yang-Mills theory, for a general gauge group and general D-dimensional covariant kinematics, and including all non-planar contributions. We use the method of maximal cuts - an efficient application of the unitarity method - to construct the result in terms of 50 four-loop integrals. We give graphical rules, valid in D-dimensions, for obtaining various non-planar contributions from previously-determined terms. We examine the ultraviolet behavior of the amplitude near D = 11/2. The non-planar terms are as well-behaved in the ultraviolet as the planar terms. However, in the color decomposition of the three- and four-loop amplitude for an SU(N{sub c}) gauge group, the coefficients of the double-trace terms are better behaved in the ultraviolet than are the single-trace terms. The results from this paper were an important step toward obtaining the corresponding amplitude in N = 8 supergravity, which confirmed the existence of cancellations beyond those needed for ultraviolet finiteness at four loops in four dimensions. Evaluation of the loop integrals near D = 4 would permit tests of recent conjectures and results concerning the infrared behavior of four-dimensional massless gauge theory.
Date: August 25, 2010
Creator: Bern, Z.; Carrasco, J.J.M.; /UCLA; Dixon, Lance J.; /CERN, /SLAC; Johansson, H. et al.
Object Type: Article
System: The UNT Digital Library
Accelerator Production Options for 99MO (open access)

Accelerator Production Options for 99MO

Shortages of {sup 99}Mo, the most commonly used diagnostic medical isotope, have caused great concern and have prompted numerous suggestions for alternate production methods. A wide variety of accelerator-based approaches have been suggested. In this paper we survey and compare the various accelerator-based approaches.
Date: August 25, 2010
Creator: Bertsche, Kirk
Object Type: Article
System: The UNT Digital Library
Solenoid Compensation for the SuperB Interaction Region (open access)

Solenoid Compensation for the SuperB Interaction Region

We present an approach for compensating adverse effects of the detector solenoid in the SuperB Interaction Region (IR). We place compensating solenoids around the IR quadrupole magnets to reduce the magnetic fields nearly to zero. This allows more operational headroom for superconducting IR magnets and avoids saturation of ferric IR magnets. We place stronger compensating solenoids between IR magnets to reverse the magnetic field direction. This allows adjusting the total integrated solenoid field to zero, which eliminates coordinate plane rotation and reduces vertical beam displacements in the IR.
Date: August 25, 2010
Creator: Bertsche, Kirk & Sullivan, Michael K.
Object Type: Article
System: The UNT Digital Library
SuperB Lattice Studies (open access)

SuperB Lattice Studies

The SuperB asymmetric e{sup +}e{sup -} collider is designed for 10{sup 36} cm{sup -2} s{sup -1} luminosity and beam energies of 6.7 and 4.18 GeV for e{sup +} and e{sup -} respectively. The High and Low Energy Rings (HER and LER) have one Interaction Point (IP) with 66 mrad crossing angle. The 1258 m rings fit to the INFN-LNF site at Frascati. The ring emittance is minimized for the high luminosity. The Final Focus (FF) chromaticity correction is optimized for maximum transverse acceptance and energy bandwidth. Included Crab Waist sextupoles suppress betatron resonances induced in the collisions with a large Piwinski angle. The LER Spin Rotator sections provide longitudinally polarized electron beam at the IP. The lattice is flexible for tuning the machine parameters and compatible with reusing the PEP-II magnets, RF cavities and other components. Details of the lattice design are presented.
Date: August 25, 2010
Creator: Biagini, M. E.; Raimondi, P.; Piminov, P.; Sinyatkin, S.; Nosochkov, Y. & Wittmer, W.
Object Type: Article
System: The UNT Digital Library
Dark Energy Camera for Blanco (open access)

Dark Energy Camera for Blanco

In order to make accurate measurements of dark energy, a system is needed to monitor the focus and alignment of the Dark Energy Camera (DECam) to be located on the Blanco 4m Telescope for the upcoming Dark Energy Survey. One new approach under development is to fit out-of-focus star images to a point spread function from which information about the focus and tilt of the camera can be obtained. As a first test of a new algorithm using this idea, simulated star images produced from a model of DECam in the optics software Zemax were fitted. Then, real images from the Mosaic II imager currently installed on the Blanco telescope were used to investigate the algorithm's capabilities. A number of problems with the algorithm were found, and more work is needed to understand its limitations and improve its capabilities so it can reliably predict camera alignment and focus.
Date: August 25, 2010
Creator: Binder, Gary A. & /SLAC, /Caltech
Object Type: Report
System: The UNT Digital Library
A New United Nations Entity for Women: Issues for Congress (open access)

A New United Nations Entity for Women: Issues for Congress

In September 2009, U.N. member states, including the United States, adopted a General Assembly resolution expressing strong support for the consolidation of four U.N. bodies addressing women's issues into one composite entity. This report discusses possible policy issues that may arise as the composite gender entity is established, including its funding mechanisms, the creation of an effective governance structure, the entity's possible impact on U.N. system in-country operational capacity, and the relationships and coordination between the entity and other U.N. system bodies. The report also discusses the entity in the context of broader U.N. reform efforts and examines the involvement of nongovernmental organizations (NGOs). Finally, it analyzes U.S. policy toward the new entity, including its possible role in U.S. foreign policy and the level and extent of U.S. financial contributions to existing U.N. system gender entities.
Date: May 25, 2010
Creator: Blanchfield, Luisa
Object Type: Report
System: The UNT Digital Library
In Situ X-Ray Diffraction of the Delta to Alpha-Prime Transformation in Pu-Ga Alloys (open access)

In Situ X-Ray Diffraction of the Delta to Alpha-Prime Transformation in Pu-Ga Alloys

None
Date: May 25, 2010
Creator: Blobaum, K. J.; Jeffries, J. R.; Wall, M. A.; Cynn, H.; Evans, W. J. & Schwartz, A. J.
Object Type: Article
System: The UNT Digital Library
War in Afghanistan: Strategy, Military Operations, and Issues for Congress (open access)

War in Afghanistan: Strategy, Military Operations, and Issues for Congress

The character of the war in Afghanistan evolved from a violent struggle against al Qaeda and its Taliban supporters to a multi-faceted counterinsurgency (COIN) effort. This report provides an examination of the war's background, context, and early execution; an analytical discussion of the COIN war to date, including strategy, organization, participation, and key facets of the effort including population security, advising the Afghan National Security Forces (ANSF), counter-narcotics, reconciliation, community outreach, and civil-military coordination; and an analysis of major strategic and operational issues and options that the 111th Congress may opt to consider.
Date: February 25, 2010
Creator: Bowman, Steve & Dale, Catherine
Object Type: Report
System: The UNT Digital Library