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Bench-Top Impedance Measurements for a Rotatable Copper Collimator for the LHC Phase II Collimation Upgrade

Description: Simulations have been performed in Omega3P to study both trapped modes and impedance contributions of a rotatable collimator for the LHC phase II collimation upgrade. Bench-top stretched coil probe impedance methods are also being implemented for measurements on prototype components to directly measure the low frequency impedance contributions. The collimator design also calls for a RF contact interface at both jaw ends with contact resistance much less than a milliohm in order to limit transve… more
Date: August 26, 2010
Creator: Smith, Jeffrey Claiborne; Bane, Karl; Doyle, Eric; Keller, Lew; Lundgren, Steve; Markiewicz, Tom et al.
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Partner: UNT Libraries Government Documents Department
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Illumination Sufficiency Survey Techniques: In-situ Measurements of Lighting System Performance and a User Preference Survey for Illuminance in an Off-Grid, African Setting

Description: 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. … more
Date: August 26, 2010
Creator: Alstone, Peter; Jacobson, Arne & Mills, Evan
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Limits on superconductivity-related magnetization in Sr 2RuO 4 and PrOs 4Sb 12 from scanning SQUID microscopy

Description: We present scanning SQUID microscopy data on the superconductors Sr{sub 2}RuO{sub 4} (T{sub c} = 1.5 K) and PrOs{sub 4}Sb{sub 12} (T{sub c} = 1.8 K). In both of these materials, superconductivity-related time-reversal symmetry-breaking fields have been observed by muon spin rotation; our aim was to visualize the structure of these fields. However in neither Sr{sub 2}RuO{sub 4} nor PrOs{sub 4}Sb{sub 12} do we observe spontaneous superconductivity-related magnetization. In Sr{sub 2}RuO{sub 4}, ma… more
Date: August 26, 2010
Creator: Moler, Kathryn
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Partner: UNT Libraries Government Documents Department
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No Prejudice in Space

Description: We present a summary of recent results obtained from a scan of the 19-dimensional parameter space of the pMSSM and its implications for dark matter searches. We have generated a large set of points in parameter space (which we call 'models') for the 19-parameter CP-conserving pMSSM, where MFV has been assumed. We subjected these models to numerous experimental and theoretical constraints to obtain a set of {approx}68 K models which are consistent with existing data. We attempted to be somewhat … more
Date: August 26, 2010
Creator: Cotta, R. C.; Gainer, J. S.; Hewett, J. L. & Rizzo, T. G.
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Partner: UNT Libraries Government Documents Department
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A Single-Shot Method for Measuring Femtosecond Bunch Length in Linac-Based Free-Electron Lasers

Description: There is growing interest in the generation and characterization of femtosecond and subfemtosecond pulses from linac-based free-electron lasers (FELs). In this report, following the method of Ricci and Smith [Phys. Rev. ST Accel. Beams 3, 032801 (2000)], we investigate the measurement of the longitudinal bunch profile of an ultrashort electron bunch produced by these FELs. We show that this method can be applied in a straightforward manner at x-ray FEL facilities such as the Linac Coherent Ligh… more
Date: August 26, 2010
Creator: Huang, Z.; Bane, K.; Ding, Y. & Emma, P.
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Partner: UNT Libraries Government Documents Department
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SXR Continuum Radiation Transmitted Through Metallic Filters: An Analytical Approach To Fast Electron Temperature Measurements

Description: A new set of analytic formulae describes the transmission of soft X-ray (SXR) continuum radiation through a metallic foil for its application to fast electron temperature measurements in fusion plasmas. This novel approach shows good agreement with numerical calculations over a wide range of plasma temperatures in contrast with the solutions obtained when using a transmission approximated by a single-Heaviside function [S. von Goeler, Rev. Sci. Instrum., 20, 599, (1999)]. The new analytic formu… more
Date: August 26, 2010
Creator: Delgado-Aparicio, L.; Tritz, K.; Kramer, T.; Stutman, D.; Finkentha, M.; Hill, K. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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'Micromanaging de Sitter holography'

Description: We develop tools to engineer de Sitter vacua with semi-holographic duals, using elliptic fibrations and orientifolds to uplift Freund-Rubin compactifications with CFT duals. The dual brane construction is compact and constitutes a microscopic realization of the dS/dS correspondence, realizing d-dimensional de Sitter space as a warped compactification down to (d-1)-dimensional de Sitter gravity coupled to a pair of large-N matter sectors. This provides a parametric microscopic interpretation of … more
Date: August 26, 2010
Creator: Dong, Xi; Horn, Bart; /SLAC /Stanford U., Phys. Dept. /Santa Barbara, KITP; Silverstein, Eva; /Santa Barbara, KITP /SLAC /Stanford U., Phys. Dept.; Torroba, Gonzalo et al.
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Partner: UNT Libraries Government Documents Department
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AdS/CFT and Large-N Volume Independence

Description: We study the Eguchi-Kawai reduction in the strong-coupling domain of gauge theories via the gravity dual of N=4 super-Yang-Mills on R{sup 3} x S{sup 1}. We show that D-branes geometrize volume independence in the center-symmetric vacuum and give supergravity predictions for the range of validity of reduced large-N models at strong coupling.
Date: August 26, 2010
Creator: Poppitz, Erich; U., /Toronto; Unsal, Mithat & /SLAC /Stanford U., Phys. Dept.
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Partner: UNT Libraries Government Documents Department
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Realization of Center Symmetry in Two Adjoint Flavor Large-N Yang-Mills

Description: We report on the results of numerical simulations of SU(N) lattice Yang Mills with two flavors of (light) Wilson fermion in the adjoint representation. We analytically and numerically address the question of center symmetry realization on lattices with {Lambda} sites in each direction in the large-N limit. We show, by a weak coupling calculation that, for massless fermions, center symmetry realization is independent of {Lambda}, and is unbroken. Then, we extend our result by conducting simulati… more
Date: August 26, 2010
Creator: Catterall, Simon; U., /Syracuse; Galvez, Richard; U., /Syracuse; Unsal, Mithat & /SLAC /Stanford U., Phys. Dept.
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Partner: UNT Libraries Government Documents Department
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e+ e- Factory Developments

Description: The impressive performance of current (KEKB) and recent (PEP-II) B-Factory colliders has increased interest in developing even higher luminosity B-factories. Two new designs are being developed (SuperKEKB and SuperB). Both designs plan to deliver a luminosity in the range of 1 x 10{sup 36} cm{sup -2}s{sup -1}, nearly 100 times the present B-factory level. Achieving this high luminosity requires high-current beams and short bunch lengths and/or a new way of colliding the beams. The SuperB design… more
Date: August 26, 2010
Creator: Sullivan, Michael
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Partner: UNT Libraries Government Documents Department
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Observation of the three-body rare decay B-> J/psi phi K

Description: 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}) =… more
Date: August 26, 2010
Creator: Aubert, B.
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Partner: UNT Libraries Government Documents Department
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Conformality or confinement: (IR)relevance of topological excitations

Description: What distinguishes two asymptotically-free non-abelian gauge theories on R{sup 4}, one of which is just below the conformal window boundary and confines, while the other is slightly above the boundary and flows to an infrared conformal field theory? In this work, we aim to answer this question for non-supersymmetric Yang-Mills theories with fermions in arbitrary chiral or vectorlike representations. We use the presence or absence of mass gap for gauge fluctuations as an identifier of the infrar… more
Date: August 26, 2010
Creator: Poppitz, Erich; U., /Toronto; Unsal, Mithat & /SLAC /Stanford U., Phys. Dept.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Bigger, Better, Faster, More at the LHC

Description: Multijet plus missing energy searches provide universal coverage for theories that have new colored particles that decay into a dark matter candidate and jets. These signals appear at the LHC further out on the missing energy tail than two-to-two scattering indicates. The simplicity of the searches at the LHC contrasts sharply with the Tevatron where more elaborate searches are necessary to separate signal from background. The searches presented in this article effectively distinguish signal fr… more
Date: August 26, 2010
Creator: Izaguirre, Eder; /SLAC; Manhart, Michael; /Rutgers U., Piscataway; Wacker, Jay G. & /SLAC
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Partner: UNT Libraries Government Documents Department
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Large-N reduction in QCD-like theories with massive adjoint fermions

Description: 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 st… more
Date: August 26, 2010
Creator: Azeyanagi, Tatsuo; U., /Kyoto; Hanada, Masanori; Inst., /Weizmann; Unsal, Mithat; /Weizmann Inst. /SLAC /Stanford U., Phys. Dept. et al.
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Partner: UNT Libraries Government Documents Department
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Massless versus Kaluza-Klein gravitons at the LHC

Description: We show that the LHC will be able to differentiate between a four-dimensional model with quantum gravity at {approx} 1 TeV where the (massless) graviton becomes strongly coupled to standard model particles at 1 TeV and brane world type models with a large extra-dimensional volume and massive Kaluza-Klein gravitons. We estimate that the 14 TeV LHC could put a limit of the order of {approx} 5 TeV on the four dimensional Planck mass in a model independent way.
Date: August 26, 2010
Creator: Calmet, Xavier; U., /Sussex; de Aquino, Priscila; /Louvain U., CP3 /Leuven U.; Rizzo, Thomas G. & /SLAC
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Partner: UNT Libraries Government Documents Department
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Observation of the decay B0bar -> LambdaC antiproton pi0

Description: 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{… more
Date: August 26, 2010
Creator: Aubert, B.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
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Partner: UNT Libraries Government Documents Department
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F-Theory Uplifts and GUTs

Description: 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 i… more
Date: August 26, 2010
Creator: Blumenhagen, Ralph; Grimm, Thomas W.; Jurke, Benjamin & Weigand, Timo
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Partner: UNT Libraries Government Documents Department
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11.424 Ghz Stripline Transversal Filter for Sub-Picosecond Bunch Timing Measurements

Description: Measurement of time-of-arrival or instantaneous longitudinal position is a fundamental beam diagnostic. We present results from a stripline transversal periodic coupler structure which forms the heart of a sub-ps beam timing detector. This filter structure approximates a sinx/x response in the frequency domain which corresponds to a limited pulse length response in the time domain. These techniques have been used extensively in beam feedback systems at 3 GHz center frequencies with operational … more
Date: August 26, 2010
Creator: Van Winkle, D.; Young, A. & Fox, J. D.
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Partner: UNT Libraries Government Documents Department
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BPM Design and Impedance Considerations for a Rotatable Collimator for the LHC Collimation Upgrade

Description: The Phase II upgrade to the LHC collimation system calls for complementing the 30 high robust Phase I graphite secondary collimators with 30 high Z Phase II collimators. This paper reports on BPM and impedance considerations and measurements of the integrated BPMs in the prototype rotatable collimator to be installed in the Super Proton Synchrotron (SPS) at CERN. The BPMs are necessary to align the jaws with the beam. Without careful design the beam impedance can result in unacceptable heating … more
Date: August 26, 2010
Creator: Smith, Jeffrey Claiborne; Keller, Lewis; Lundgren, Steven; Markiewicz, Thomas & Young, Andrew
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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On the Physical Relevance of the Study of gamma* gamma -> pi pi at small t and large Q2

Description: We discuss the relevance of a dedicated measurement of exclusive production of a pair of neutral pions in a hard {gamma}*{gamma} scattering at small momentum transfer. In this case, the virtuality of one photon provides us with a hard scale in the process, enabling us to perform a QCD calculation of this reaction rate using the concept of Transition Distribution Amplitudes (TDA). Those are related by sum rules to the pion axial form factor F{sub A}{sup {pi}} and, as a direct consequence, a cros… more
Date: August 26, 2010
Creator: Lansberg, J. P.; Pire, B. & Szymanowski, L.
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Partner: UNT Libraries Government Documents Department
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Gravity Waves and Linear Inflation From Axion Monodromy

Description: Wrapped branes in string compactifications introduce a monodromy that extends the field range of individual closed-string axions to beyond the Planck scale. Furthermore, approximate shift symmetries of the system naturally control corrections to the axion potential. This suggests a general mechanism for chaotic inflation driven by monodromy-extended closed-string axions. We systematically analyze this possibility and show that the mechanism is compatible with moduli stabilization and can be rea… more
Date: August 26, 2010
Creator: McAllister, Liam; /Cornell U., LEPP /Cornell U., Phys. Dept.; Silverstein, Eva; Westphal, Alexander & /SLAC /Stanford U., Phys. Dept.
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Partner: UNT Libraries Government Documents Department
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Retrofitting and the mu Problem

Description: One of the challenges of supersymmetry (SUSY) breaking and mediation is generating a {mu} term consistent with the requirements of electro-weak symmetry breaking. The most common approach to the problem is to generate the {mu} term through a SUSY breaking F-term. Often these models produce unacceptably large B{mu} terms as a result. We will present an alternate approach, where the {mu} term is generated directly by non-perturtative effects. The same non-perturbative effect will also retrofit th… more
Date: August 26, 2010
Creator: Green, Daniel; Weigand, Timo & /SLAC /Stanford U., Phys. Dept.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Large-N volume independence in conformal and confining gauge theories

Description: Consequences of large N volume independence are examined in conformal and confining gauge theories. In the large N limit, gauge theories compactified on R{sup d-k} x (S{sup 1}){sup k} are independent of the S{sup 1} radii, provided the theory has unbroken center symmetry. In particular, this implies that a large N gauge theory which, on R{sup d}, flows to an IR fixed point, retains the infinite correlation length and other scale invariant properties of the decompactified theory even when compac… more
Date: August 26, 2010
Creator: Unsal, Mithat & Yaffe, Laurence G.
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Partner: UNT Libraries Government Documents Department
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