Results of applying a non-evaporative mitigation technique to laser-initiated surface damage on fused-silica (open access)

Results of applying a non-evaporative mitigation technique to laser-initiated surface damage on fused-silica

We present results from a study to determine an acceptable CO{sub 2} laser-based non-evaporative mitigation protocol for use on surface damage sites in fused-silica optics. A promising protocol is identified and evaluated on a set of surface damage sites created under ICF-type laser conditions. Mitigation protocol acceptability criteria for damage re-initiation and growth, downstream intensification, and residual stress are discussed. In previous work, we found that a power ramp at the end of the protocol effectively minimizes the residual stress (<25 MPa) left in the substrate. However, the biggest difficulty in determining an acceptable protocol was balancing between low re-initiation and problematic downstream intensification. Typical growing surface damage sites mitigated with a candidate CO{sub 2} laser-based mitigation protocol all survived 351 nm, 5 ns damage testing to fluences >12.5 J/cm{sup 2}. The downstream intensification arising from the mitigated sites is evaluated, and all but one of the sites has 100% passing downstream damage expectation values. We demonstrate, for the first time, a successful non-evaporative 10.6 {micro}m CO{sub 2} laser mitigation protocol applicable to fused-silica optics used on fusion-class lasers like the National Ignition Facility (NIF).
Date: October 26, 2010
Creator: Adams, J. J.; Bolourchi, M.; Bude, J. D.; Guss, G. M.; Matthews, M. J. & Nostrand, M. C.
Object Type: Article
System: The UNT Digital Library
Silicon Detector Letter of Intent (open access)

Silicon Detector Letter of Intent

This document presents the current status of SiD's effort to develop an optimized design for an experiment at the International Linear Collider. It presents detailed discussions of each of SiD's various subsystems, an overview of the full GEANT4 description of SiD, the status of newly developed tracking and calorimeter reconstruction algorithms, studies of subsystem performance based on these tools, results of physics benchmarking analyses, an estimate of the cost of the detector, and an assessment of the detector R&D needed to provide the technical basis for an optimised SiD.
Date: May 26, 2010
Creator: Aihara, H.; Burrows, P. & Oreglia, M.
Object Type: Report
System: The UNT Digital Library
Illumination Sufficiency Survey Techniques: In-situ Measurements of Lighting System Performance and a User Preference Survey for Illuminance in an Off-Grid, African Setting (open access)

Illumination Sufficiency Survey Techniques: In-situ Measurements of Lighting System Performance and a User Preference Survey for Illuminance in an Off-Grid, African Setting

Efforts to promote rechargeable electric lighting as a replacement for fuel-based light sources in developing countries are typically predicated on the notion that lighting service levels can be maintained or improved while reducing the costs and environmental impacts of existing practices. However, the extremely low incomes of those who depend on fuel-based lighting create a need to balance the hypothetically possible or desirable levels of light with those that are sufficient and affordable. In a pilot study of four night vendors in Kenya, we document a field technique we developed to simultaneously measure the effectiveness of lighting service provided by a lighting system and conduct a survey of lighting service demand by end-users. We took gridded illuminance measurements across each vendor's working and selling area, with users indicating the sufficiency of light at each point. User light sources included a mix of kerosene-fueled hurricane lanterns, pressure lamps, and LED lanterns.We observed illuminance levels ranging from just above zero to 150 lux. The LED systems markedly improved the lighting service levels over those provided by kerosene-fueled hurricane lanterns. Users reported that the minimum acceptable threshold was about 2 lux. The results also indicated that the LED lamps in use by the …
Date: August 26, 2010
Creator: Alstone, Peter; Jacobson, Arne & Mills, Evan
Object Type: Report
System: The UNT Digital Library
Fermi surface of SrFe2P2 determined by de Haas-van Alphen effect (open access)

Fermi surface of SrFe2P2 determined by de Haas-van Alphen effect

We report measurements of the Fermi surface (FS) of the ternary iron-phosphide SrFe{sub 2}P{sub 2} using the de Haas-van Alphen effect. The calculated FS of this compound is very similar to SrFe{sub 2}As{sub 2}, the parent compound of the high temperature superconductors. Our data show that the Fermi surface is composed of two electron and two hole sheets in agreement with bandstructure calculations. Several of the sheets show strong c-axis warping emphasizing the importance of three-dimensionality in the non-magnetic state of the ternary pnictides. We find that the electron and hole pockets have a different topology, implying that this material does not satisfy a ({pi},{pi}) nesting condition.
Date: May 26, 2010
Creator: Analytis, J.G.
Object Type: Article
System: The UNT Digital Library
Quantum Oscillations in the Parent pnictide BaFe2As2 : Itinerant Electrons in the Reconstructed State (open access)

Quantum Oscillations in the Parent pnictide BaFe2As2 : Itinerant Electrons in the Reconstructed State

We report quantum oscillation measurements that enable the direct observation of the Fermi surface of the low temperature ground state of BaFe{sub 2}As{sub 2}. From these measurements we characterize the low energy excitations, revealing that the Fermi surface is reconstructed in the antiferromagnetic state, but leaving itinerant electrons in its wake. The present measurements are consistent with a conventional band folding picture of the antiferromagnetic ground state, placing important limits on the topology and size of the Fermi surface.
Date: May 26, 2010
Creator: Analytis, J.G.
Object Type: Article
System: The UNT Digital Library
Chemistry, phase formation, and catalytic activity of thin palladium-containing oxide films synthesized by plasma-assisted physical vapor deposition (open access)

Chemistry, phase formation, and catalytic activity of thin palladium-containing oxide films synthesized by plasma-assisted physical vapor deposition

The chemistry, microstructure, and catalytic activity of thin films incorporating palladium were studied using scanning and transmission electron microscopies, X-ray diffraction, spectrophotometry, 4-point probe and catalytic tests. The films were synthesized using pulsed filtered cathodic arc and magnetron sputter deposition, i.e. techniques far from thermodynamic equilibrium. Catalytic particles were formed by thermally cycling thin films of the Pd-Pt-O system. The evolution and phase formation in such films as a function of temperature were discussed in terms of the stability of PdO and PtO2 in air. The catalytic efficiency was found to be strongly affected by the chemical composition, with oxidized palladium definitely playing a major role in the combustion of methane. Reactive sputter deposition of thin films in the Pd-Zr-Y-O system allowed us forming microstructures ranging from nanocrystalline zirconia to palladium nanoparticles embedded in a (Zr,Y)4Pd2O matrix. The sequence of phase formation is put in relation to simple thermodynamic considerations.
Date: November 26, 2010
Creator: Anders, Andre
Object Type: Article
System: The UNT Digital Library
Flavor Physics in the Quark Sector (open access)

Flavor Physics in the Quark Sector

In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved, apart from their masses and quantum numbers, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. In the past, observations of CP violation were confined to neutral K mesons, but since the early 1990s, a large number of CP-violating processes have been studied in detail in neutral B mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of K,D, and B mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of …
Date: August 26, 2010
Creator: Antonelli, Mario; Asner, David Mark; Bauer, Daniel Adams; Becher, Thomas G.; Beneke, M.; Bevan, Adrian John et al.
Object Type: Article
System: The UNT Digital Library
The European Parliament (open access)

The European Parliament

This report provides background on the Congress-European Parliament (EP) relationship and the role of the Transatlantic Legislators' Dialogue (TLD). It also explores potential future options that could strengthen ties between the two bodies.
Date: January 26, 2010
Creator: Archick, Kristin
Object Type: Report
System: The UNT Digital Library
Improved Meteorological Input for Atmospheric Release Decision support Systems and an Integrated LES Modeling System for Atmospheric Dispersion of Toxic Agents: Homeland Security Applications (open access)

Improved Meteorological Input for Atmospheric Release Decision support Systems and an Integrated LES Modeling System for Atmospheric Dispersion of Toxic Agents: Homeland Security Applications

When hazardous material is accidently or intentionally released into the atmosphere, emergency response organizations look to decision support systems (DSSs) to translate contaminant information provided by atmospheric models into effective decisions to protect the public and emergency responders and to mitigate subsequent consequences. The Department of Homeland Security (DHS)-led Interagency Modeling and Atmospheric Assessment Center (IMAAC) is one of the primary DSSs utilized by emergency management organizations. IMAAC is responsible for providing 'a single piont for the coordination and dissemination of Federal dispersion modeling and hazard prediction products that represent the Federal position' during actual or potential incidents under the National Response Plan. The Department of Energy's (DOE) National Atmospheric Release Advisory Center (NARAC), locatec at the Lawrence Livermore National Laboratory (LLNL), serves as the primary operations center of the IMAAC. A key component of atmospheric release decision support systems is meteorological information - models and data of winds, turbulence, and other atmospheric boundary-layer parameters. The accuracy of contaminant predictions is strongly dependent on the quality of this information. Therefore, the effectiveness of DSSs can be enhanced by improving the meteorological options available to drive atmospheric transport and fate models. The overall goal of this project was to develop and …
Date: April 26, 2010
Creator: Arnold, E; Simpson, M; Larsen, S; Gash, J; Aluzzi, F; Lundquist, J et al.
Object Type: Report
System: The UNT Digital Library
Observation of the three-body rare decay B-> J/psi phi K (open access)

Observation of the three-body rare decay B-> J/psi phi K

The authors report the study of the B meson decays B{sup {+-}} {yields} J/{psi}{phi}K{sup {+-}}, B{sup 0} {yields} J/{psi}{phi}K{sup 0} using 433 million of B{bar B} events collected at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II e{sup +}e{sup -} asymmetric-energy collider. They obtain the branching fraction measurements: {Beta}(B{sup {+-}} {yields} J{psi}{phi}K{sup {+-}}) = (5.6 {+-} 0.9(stat) {+-} 0.3(sys)) x 10{sup -5}, {Beta}(B{sup {+-}} {yields} J{psi}{phi}K{sup 0}) = (5.4 {+-} 1.2(stat) {+-} 0.4(sys)) x 10{sup -5}.
Date: August 26, 2010
Creator: Aubert, B.
Object Type: Article
System: The UNT Digital Library
Observation of the decay B0bar -> LambdaC antiproton pi0 (open access)

Observation of the decay B0bar -> LambdaC antiproton pi0

In a sample of 467 million B{bar B} pairs collected with the BABAR detector at the PEP-II collider at SLAC we have observed the decay {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup 0} and measured the branching fraction to be (1.94 {+-} 0.17 {+-} 0.14 {+-} 0.50) x 10{sup -4}, where the uncertainties are statistical, systematic, and the uncertainty on the {Lambda}{sub c}{sup +} {yields} pK{sup -}{pi}{sup +} branching fraction, respectively. We determine an upper limit of 1.5 x 10{sup -6} at 90% C.L. for the product branching fraction {Beta}({bar B}{sup 0} {yields} {Sigma}{sub c}{sup +}(2455){bar p}) x {Beta}({Lambda}{sub c}{sup +} {yields} pK{sup -}{pi}{sup +}). Furthermore, we observe an enhancement at the threshold of the invariant mass of the baryon-antibaryon pair.
Date: August 26, 2010
Creator: Aubert, B.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Object Type: Article
System: The UNT Digital Library
Measurement of CP violation observables and parameters for the decays $B^{\pm}\to DK^{*\pm}$ (open access)

Measurement of CP violation observables and parameters for the decays $B^{\pm}\to DK^{*\pm}$

We study the decay B{sup -} {yields} DK*{sup -} using a sample of 379 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II B-factory. We perform a 'GLW' analysis where the D meson decays into either a CP-even (CP+) eigenstate (K{sup +}K{sup -}, {pi}{sup +}{pi}{sup -}), CP-odd (CP-) eigenstate (K{sub S}{sup 0}{pi}{sup 0}, K{sub S}{sup 0}{phi}, K{sub S}{sup 0}{omega}) or a non-CP state (K{sup -}{pi}{sup +}). We also analyze D meson decays into K{sup +}{pi}{sup -} from a Cabibbo-favored {bar D}{sup 0} decay or doubly suppressed D{sup 0} decay ('ADS' analysis). We measure observables that are sensitive to the CKM angle {gamma}: the partial-rate charge asymmetries A{sub CP{+-}}, the ratios R{sub CP{+-}} of the B-decay branching fractions in CP{+-} and non-CP decay, the ratio R{sub ADS} of the charge-averaged branching fractions, and the charge asymmetry A{sub ADS} of the ADS decays: A{sub CP+} = 0.09 {+-} 0.13 {+-} 0.06, A{sub CP-} = -0.23 {+-} 0.21 {+-} 0.07, R{sub CP+} = 2.17 {+-} 0.35 {+-} 0.09, R{sub CP-} = 1.03 {+-} 0.27 {+-} 0.13, R{sub ADS} = 0.066 {+-} 0.031 {+-} 0.010, and A{sub ADS} = -0.34 {+-} 0.43 {+-} 0.16, where the first …
Date: August 26, 2010
Creator: Aubert, Bernard; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Object Type: Article
System: The UNT Digital Library
Mechanics of Individual, Isolated Vortices in a Cuprate Superconductor (open access)

Mechanics of Individual, Isolated Vortices in a Cuprate Superconductor

None
Date: May 26, 2010
Creator: Auslaender, O.M.
Object Type: Article
System: The UNT Digital Library
Large-N reduction in QCD-like theories with massive adjoint fermions (open access)

Large-N reduction in QCD-like theories with massive adjoint fermions

Large-N QCD with heavy adjoint fermions emulates pure Yang-Mills theory at long distances. We study this theory on a four- and three-torus, and analytically argue the existence of a large-small volume equivalence. For any finite mass, center symmetry unbroken phase exists at sufficiently small volume and this phase can be used to study the large-volume limit through the Eguchi-Kawai equivalence. A finite temperature version of volume independence implies that thermodynamics on R3 x S1 can be studied via a unitary matrix quantum mechanics on S1, by varying the temperature. To confirm this non-perturbatively, we numerically study both zero- and one-dimensional theories by using Monte-Carlo simulation. Order of finite-N corrections turns out to be 1/N. We introduce various twisted versions of the reduced QCD which systematically suppress finite-N corrections. Using a twisted model, we observe the confinement/deconfinement transition on a 1{sup 3} x 2-lattice. The result agrees with large volume simulations of Yang-Mills theory. We also comment that the twisted model can serve as a non-perturbative formulation of the non-commutative Yang-Mills theory.
Date: August 26, 2010
Creator: Azeyanagi, Tatsuo; U., /Kyoto; Hanada, Masanori; Inst., /Weizmann; Unsal, Mithat; /Weizmann Inst. /SLAC /Stanford U., Phys. Dept. et al.
Object Type: Article
System: The UNT Digital Library
INDEPENDENT VERIFICATION REVIEW AND SURVEY of the Argonne National Laboratory Building 301 Footprint (open access)

INDEPENDENT VERIFICATION REVIEW AND SURVEY of the Argonne National Laboratory Building 301 Footprint

INDEPENDENT VERIFICATION REVIEW AND SURVEY of the Argonne National Laboratory Building 301 Footprint, Argonne Illinois 5061-SR-01-0
Date: May 26, 2010
Creator: Bailey, E.N.
Object Type: Report
System: The UNT Digital Library
IMPEDANCE CONSIDERATIONS FOR THE DESIGN OF THE VACUUM SYSTEM OF THE CERN PS2 (open access)

IMPEDANCE CONSIDERATIONS FOR THE DESIGN OF THE VACUUM SYSTEM OF THE CERN PS2

In order for the LHC to reach an ultimate luminosity goal of 10{sup 35}/cm{sup 2}/s, CERN is considering upgrade options for the LHC injector chain, including a new 50 GeV synchrotron of about 1.3 km length for protons and heavy ions, to be called the PS2 [1]. The proton energy will be ramped from 4 GeV to 50 GeV in 1.2 s, and the design proton current for LHC operation is 2.7 A. In the LARP framework, we are studying the instability thresholds and the impedance requirements of the vacuum system for the PS2. Goal of this study is to develop an impedance budget for the machine. We consider the standard single and multi-bunch collective effects that may be an issue in the PS2. For single bunch, we study the microwave instability and the transverse mode coupling instability (TMCI); for multi-bunch, the transverse coupled bunch instability. While the impedance budget will include many components in the machine, at present, we only have sufficient information to include the resistance of the beam pipe, the vacuum flanges that connect the various pieces of the vacuum chamber, and space charge impedance in our estimate. Note that earlier estimates of the impedance and its …
Date: August 26, 2010
Creator: Bane, K.L.F.; Stupakov, G.; Wienands, U.; Benedikt, M.; Grudiev, A.; Mahner, E. et al.
Object Type: Article
System: The UNT Digital Library
Impeachment: An Overview of Constitutional Provisions, Procedure, and Practice (open access)

Impeachment: An Overview of Constitutional Provisions, Procedure, and Practice

On June 19, 2009, the House voted to impeach U.S. District Judge Samuel B. Kent of the U.S. District Court for the Southern District of Texas. The impeachment process provides a mechanism for removal of the President, Vice President, and other federal civil officers found to have engaged in "treason, bribery, or other high crimes and misdemeanors." This report explains the impeachment process, including its history and the process itself.
Date: April 26, 2010
Creator: Bazan, Elizabeth B. & Henning, Anna C.
Object Type: Report
System: The UNT Digital Library
A Twisted Ladder: Relating the Fe Superconductors to the High Tc Cuprates (open access)

A Twisted Ladder: Relating the Fe Superconductors to the High Tc Cuprates

We construct a 2-leg ladder model of an Fe-pnictide superconductor and discuss its properties and relationship with the familiar 2-leg cuprate model. Our results suggest that the underlying pairing mechanism for the Fe-pnictide superconductors is similar to that for the cuprates.
Date: May 26, 2010
Creator: Berg, E.
Object Type: Article
System: The UNT Digital Library
Intelligence Issues for Congress (open access)

Intelligence Issues for Congress

This report discusses the efforts currently underway to improve coordination and encourage better analysis amongst the various agencies within the U.S. Intelligence Community, especially with regard to the ongoing and prominent issue of international terrorism. In particular, this report addresses the false intelligence regarding Iraqi weapons of mass destruction and the current efforts in Iraq and Iran in general.
Date: February 26, 2010
Creator: Best, Richard A., Jr.
Object Type: Report
System: The UNT Digital Library
Director of National Intelligence Statutory Authorities: Status and Proposals (open access)

Director of National Intelligence Statutory Authorities: Status and Proposals

This report discusses the Director of National Intelligence (DNI) position created by the Intelligence Reform and Terrorism Prevention Act of 2004 (P.L. 108-458). It includes an overview of the authorities granted to the DNI by legislation in 2004 and later as well as the varying opinions of Congress regarding new DNI authorities, as well as related legislation from FY2010 through FY2012.
Date: May 26, 2010
Creator: Best, Richard A., Jr. & Cumming, Alfred
Object Type: Report
System: The UNT Digital Library
P1-Marx Modulator for the ILC (open access)

P1-Marx Modulator for the ILC

A first generation prototype, P1, Marx-topology klystron modulator has been developed at the SLAC National Accelerator Laboratory for the International Linear Collider (ILC) project. It is envisioned as a lower cost, smaller footprint, and higher reliability alternative to the present, bouncer-topology, baseline design. The application requires 120 kV (+/-0.5%), 140 A, 1.6 ms pulses at a rate of 5 Hz. The Marx constructs the high voltage pulse by combining, in series, a number of lower voltage cells. The Marx employs solid state elements; IGBTs and diodes, to control the charge, discharge and isolation of the cells. Active compensation of the output is used to achieve the voltage regulation while minimizing the stored energy. The P1-Marx has been integrated into a test stand with a 10 MW L-band klystron, where each is undergoing life testing. A review of the P1-Marx design and its operational history in the L-band test stand are presented.
Date: August 26, 2010
Creator: Beukers, T.; Burkhart, C.; Kemp, M.; Larsen, R.; Nguyen, M.; Olsen, J. et al.
Object Type: Article
System: The UNT Digital Library
Super-B Project Overview (open access)

Super-B Project Overview

The SuperB project aims at the construction of an asymmetric very high luminosity B-Factory on the Frascati/Tor Vergata (Italy) area, providing a uniquely sensitive probe of New Physics in the flavour sector of the Standard Model. The luminosity goal of 10{sup 36} cm{sup -2} s{sup -1} can be reached with a new collision scheme with 'large Piwinski angle' (LPA) and the use of 'crab waist sextupoles' (CW). A LPA&CW Interaction Region (IR) has been successfully tested at the DA{Phi}NE {Phi}-Factory at LNF-Frascati in 2008. The LPA&CW scheme, together with very low {beta}*, will allow for operation with relatively low beam currents and reasonable bunch length, comparable to those of PEP-II and KEKB. In the High Energy Ring (HER), two spin rotators will bring longitudinally polarized beams into collision at the IP. The lattice has been designed with a very low intrinsic emittance and is quite compact, less than 2 km long. The tight focusing requires the final doublet quadrupoles to be very close to the IP and very compact. A Conceptual Design Report was published in March 2007, and beam dynamics and collective effects R&D studies are in progress in order to publish a Technical Design Report by the end …
Date: August 26, 2010
Creator: Biagini, M.E.; Boni, R.; Boscolo, M.; Demma, T.; Drago, A.; Guiducci, S. et al.
Object Type: Article
System: The UNT Digital Library
F-Theory Uplifts and GUTs (open access)

F-Theory Uplifts and GUTs

We study the F-theory uplift of Type IIB orientifold models on compact Calabi-Yau threefolds containing divisors which are del Pezzo surfaces. We consider two examples defined via del Pezzo transitions of the quintic. The first model has an orientifold projection leading to two disjoint O7-planes and the second involution acts via an exchange of two del Pezzo surfaces. The two uplifted fourfolds are generically singular with minimal gauge enhancements over a divisor and, respectively, a curve in the non-Fano base. We study possible further degenerations of the elliptic fiber leading to F-theory GUT models based on subgroups of E{sub 8}.
Date: August 26, 2010
Creator: Blumenhagen, Ralph; Grimm, Thomas W.; Jurke, Benjamin & Weigand, Timo
Object Type: Article
System: The UNT Digital Library
Global F-theory GUTs (open access)

Global F-theory GUTs

We construct global F-theory GUT models on del Pezzo surfaces in compact Calabi-Yau fourfolds realized as complete intersections of two hypersurface constraints. The intersections of the GUT brane and the flavour branes as well as the gauge flux are described by the spectral cover construction. We consider a split S[U(4) x U(1){sub X}] spectral cover, which allows for the phenomenologically relevant Yukawa couplings and GUT breaking to the MSSM via hypercharge flux while preventing dimension-4 proton decay. General expressions for the massless spectrum, consistency conditions and a new method for the computation of curvature-induced tadpoles are presented. We also provide a geometric toolkit for further model searches in the framework of toric geometry. Finally, an explicit global model with three chiral generations and all required Yukawa couplings is defined on a Calabi-Yau fourfold which is fibered over the del Pezzo transition of the Fano threefold P{sup 4}.
Date: August 26, 2010
Creator: Blumenhagen, Ralph; Grimm, Thomas W.; Jurke, Benjamin & Weigand, Timo
Object Type: Article
System: The UNT Digital Library