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University of Nebraska - Lincoln

2006

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Articles 1 - 30 of 147

Full-Text Articles in Physics

Measurement Of The BS0 Lifetime Using Semileptonic Decays, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Dec 2006

Measurement Of The BS0 Lifetime Using Semileptonic Decays, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We report a measurement of the Bs0 lifetime in the semileptonic decay channel Bs0 → Ds- μ+νX (and its charge conjugate), using approximately 0.4 fb-1 of data collected with the D0 detector during 2002–2004. Using 5176 reconstructed Ds- μ+ signal events, we have measured the Bs0 lifetime to be τ(Bs0) = 1.398 ± 0.044(stat) -0.025+0.028(syst) ps. This is the most precise measurement of the Bs0 lifetime to date.

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Thickness Profiles Through Fatigued Bulk Ceramic Lead Zirconate Titanate, Nina Balke, Doru C. Lupascu, Thomas Blair Dec 2006

Thickness Profiles Through Fatigued Bulk Ceramic Lead Zirconate Titanate, Nina Balke, Doru C. Lupascu, Thomas Blair

Alexei Gruverman Publications

Wedge-cut samples of fatigued ferroelectric lead zirconate titanate ceramics were investigated using piezoresponse force microscopy in conjunction with conventional electrical hysteresis measurements. The local clamping of domains is monitored at different depths in the sample. The coercive fields in grains near the electrodes differ for different materials and preparation methods of the electrodes. For silver, fatigue consistently generates a space charge in the depth of the sample. For platinum electrodes, the fatigue behavior scatters strongly. Microscopically, it either occurs directly underneath the electrodes or resembles the behavior of the silver electrodes in other samples.

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Measurement Of BD Mixing Using Opposite-Side Flavor Tagging, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration Dec 2006

Measurement Of BD Mixing Using Opposite-Side Flavor Tagging, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We report on a measurement of the Bd0 mixing frequency and the calibration of an opposite-side flavor tagger in the D0 experiment. Various properties associated with the b quark on the opposite side of the reconstructed B meson are combined using a likelihood-ratio method into a single variable with enhanced tagging power. Its performance is tested with data, using a large sample of reconstructed semileptonic B → μD0X and B → μD*X decays, corresponding to an integrated luminosity of approximately 1 fb-1. The events are divided into groups depending on …

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Structural Study Of Mn-Doped Zno Fi Lms By Tem, Xingzhong Li, Jun Zhang, David J. Sellmyer Dec 2006

Structural Study Of Mn-Doped Zno Fi Lms By Tem, Xingzhong Li, Jun Zhang, David J. Sellmyer

David Sellmyer Publications

The structural study of diluted magnetic semiconductors is important for interpreting the ferromagnetic behavior associated with the materials. In the present work, a series of low concentration Mn-doped ZnO thin films synthesized by pulsed laser deposition was studied by electron microscopy. All films show the wurtzite structure with (001) preferred growth orientation on the Si substrate. Electron diffraction experiments indicate the deterioration of the growth orientation in some areas of the films with increasing Mn concentration, and the existence of a secondary phase, of Mn2O3-type, in the films with larger Mn concentrations. High-resolution electron microscopy images …

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Modulational Instability In A Layered Kerr Medium: Theory And Experiment, Martin Centurion, Mason A. Porter, Ye Pu, P. G. Kevrekidis, D. J. Frantzeskakis, Demetri Psaltis Dec 2006

Modulational Instability In A Layered Kerr Medium: Theory And Experiment, Martin Centurion, Mason A. Porter, Ye Pu, P. G. Kevrekidis, D. J. Frantzeskakis, Demetri Psaltis

Martin Centurion Publications

We present the first experimental investigation of modulational instability in a layered Kerr medium. The particularly interesting and appealing feature of our configuration, consisting of alternating glass-air layers, is the piecewise-constant nature of the material properties, which allows a theoretical linear stability analysis leading to a Kronig-Penney equation whose forbidden bands correspond to the modulationally unstable regimes. We find very good quantitative agreement between theoretical, numerical, and experimental diagnostics of the modulational instability. Because of the periodicity in the evolution variable arising from the layered medium, there are multiple instability regions rather than just one as in a uniform medium.

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Optical And X-Ray Variability Of Agns, C. Martin Gaskell Dec 2006

Optical And X-Ray Variability Of Agns, C. Martin Gaskell

C. Martin Gaskell Publications

I present new comparisons of AGN optical, UV, and X-ray variations. These reveal complex relationships between the different passbands that can change with time in a given object. While there is evidence from several objects that X-ray and optical activity levels are correlated on long timescales, variations on shorter timescales can occur independently. It is proposed that the combination of correlated and uncorrelated short-timescale variability is a consequence of anisotropic high-energy emission. It is also argued that the correlation between X-ray and optical variability on long timescales must be due to a common underlying factor and not to reprocessing of …

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Optical Variability Of The Three Brightest Nearby Quasars, C. Martin Gaskell, Andrew J. Benker, Jeffrey S. Campbell, Thomas A. George, Cecilia H. Hedrick, Mary E. Hiller, Elizabeth S. Klimek, Joseph P. Leonard, Shoji Masatoshi, Bradley W. Peterson, Kelly S. Peterson, Kelly M. Sanders Dec 2006

Optical Variability Of The Three Brightest Nearby Quasars, C. Martin Gaskell, Andrew J. Benker, Jeffrey S. Campbell, Thomas A. George, Cecilia H. Hedrick, Mary E. Hiller, Elizabeth S. Klimek, Joseph P. Leonard, Shoji Masatoshi, Bradley W. Peterson, Kelly S. Peterson, Kelly M. Sanders

C. Martin Gaskell Publications

We report on the relative optical variability of the three brightest nearby quasars, 3C 273, PDS 456, and PHL 1811. All three have comparable absolute magnitudes, but PDS 456 and PHL 1811 are radio quiet. PDS 456 is a broadline object, but PHL 1811 could be classified as a high-luminosity Narrow-Line Seyfert 1 (NLS1). Both of the radio-quiet quasars show significant variability on a timescale of a few days. The seasonal rms V-band variability amplitudes of 3C 273 and PDS 456 are indistinguishable, and the seasonal rms variability amplitude of PHL 1811 was only exceeded by 3C 273 once in …

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The Origin Of Wavelength-Dependent Continuum Delays In Agns – A New Model, C. Martin Gaskell Dec 2006

The Origin Of Wavelength-Dependent Continuum Delays In Agns – A New Model, C. Martin Gaskell

C. Martin Gaskell Publications

A model of wavelength-dependent lags in optical continuum variability of AGNs is proposed which avoids the problems of the popular “lamppost” model. Rather than being due to reprocessing of high-energy radiation from a hypothetical source above the accretion disk, the wavelength-dependent delays observed from the B to I bands are instead due to contamination of an intrinsically coherently variable continuum with the Wien tail of the thermal emission from the hot dust in the surrounding torus. The new model correctly gives the size, wavelength dependence, and luminosity dependence of the lags, and quantitatively predicts observed color hysteresis. The model also …

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A Handheld Neutron-Detection Sensor System Utilizing A New Class Of Boron Carbide Diode, Kevin Osberg, Nathan Schemm, M. Susan Hallbeck, Sina Balkir, Peter A. Dowben, Jennifer I. Brand, Michael W. Hoffman Dec 2006

A Handheld Neutron-Detection Sensor System Utilizing A New Class Of Boron Carbide Diode, Kevin Osberg, Nathan Schemm, M. Susan Hallbeck, Sina Balkir, Peter A. Dowben, Jennifer I. Brand, Michael W. Hoffman

Peter Dowben Publications

A handheld neutron-detection sensor application is described in this paper. The sensor system utilizes a new class of boron carbide diode that interacts with incoming neutrons. To interface with the boron carbide diode, an integrated front end is designed in a 1.5-μm standard CMOS technology. With the diode and front-end microchip, a handheld neutron-detection system was realized with an embedded microcontroller for real-time processing. The handheld detector operation was then tested with a plutonium–beryllium neutron source. Test and measurement results confirm the validity of the approach and the functionality of the design.

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The All Boron Carbide Diode Neutron Detector: Comparison With Theory, A. N. Caruso, Peter A. Dowben, S. Balkir, Nathan Schemm, Kevin Osberg, R.W. Fairchild, Oscar Barrios Flores, Snjezana Balaz, A.D. Harken, Brian W. Robertson, Jennifer I. Brand Nov 2006

The All Boron Carbide Diode Neutron Detector: Comparison With Theory, A. N. Caruso, Peter A. Dowben, S. Balkir, Nathan Schemm, Kevin Osberg, R.W. Fairchild, Oscar Barrios Flores, Snjezana Balaz, A.D. Harken, Brian W. Robertson, Jennifer I. Brand

Peter Dowben Publications

A boron carbide diode detector, fabricated from two different polytypes of semiconducting boron carbide, will detect neutrons in reasonable agreement with theory. Small deviations from the model calculations occur due to the detection efficiencies of the 10B capture products Li plus α sum signal differing somewhat from expectation in the thin diodes. The performance of the all boron carbide neutron detector does depart from the behavior of devices where a boron rich neutron capture layer is distinct from the diode charge collection region (i.e. a conversion layer solid state detector), as is expected.

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Measurement Of The Top Quark Mass In The Lepton +Jets Final State With The Matrix Element Method, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Nov 2006

Measurement Of The Top Quark Mass In The Lepton +Jets Final State With The Matrix Element Method, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We present a measurement of the top quark mass with the matrix element method in the lepton +jets final state. As the energy scale for calorimeter jets represents the dominant source of systematic uncertainty, the matrix element likelihood is extended by an additional parameter, which is defined as a global multiplicative factor applied to the standard energy scale. The top quark mass is obtained from a fit that yields the combined statistical and systematic jet energy scale uncertainty. Using a data set of 0.4 fb-1 taken with the D0 experiment at Run II of the Fermilab Tevatron Collider, the …

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Domain Overlap In Antiferromagnetically Coupled [Co/Pt]/Nio/ [Co/Pt] Multilayers, Andrew Baruth, Lu Yuan, John D. Burton, Karolina Janicka, Evgeny Y. Tsymbal, Sy_Hwang Liou, Shireen Adenwalla Nov 2006

Domain Overlap In Antiferromagnetically Coupled [Co/Pt]/Nio/ [Co/Pt] Multilayers, Andrew Baruth, Lu Yuan, John D. Burton, Karolina Janicka, Evgeny Y. Tsymbal, Sy_Hwang Liou, Shireen Adenwalla

Sy-Hwang Liou Publications

Antiferromagnetically coupled magnetic thin films with perpendicular anisotropy exhibit domain overlap regions originating from magnetostatic stray fields localized in the vicinity of the domain walls. Using high resolution magnetic force microscopy, the authors investigate these overlap regions in [Co/Pt] /NiO/ [Co/Pt] multilayers with various strengths of the interlayer exchange coupling. They develop a simple model that provides a quantitative explanation of the formation of these regions and the relationship between the domain overlap width and the coupling strength. Their results are important for application of magnetic layered structures with perpendicular anisotropy in advanced magnetoresistive devices.

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High-Resolution Imaging Of Proteins In Human Teeth By Scanning Probe Microscopy, Alexei Gruverman, D. Wu, B. J. Rodriguez, Sergei V. Kalinin, S. Habelitz Nov 2006

High-Resolution Imaging Of Proteins In Human Teeth By Scanning Probe Microscopy, Alexei Gruverman, D. Wu, B. J. Rodriguez, Sergei V. Kalinin, S. Habelitz

Alexei Gruverman Publications

High-resolution studies of dental tissues are of considerable interest for biomedical engineering and clinical applications. In this paper, we demonstrate the application of piezoresponse force microscopy (PFM) to nanoscale imaging of internal structure of human teeth by monitoring the local mechanical response to an electrical bias applied via a conductive tip. It is shown that PFM is capable of detecting dissimilar components of dental tissues, namely, proteins and calcified matrix, which have resembling morphology but different piezoelectric properties. It is demonstrated that collagen fibrils revealed in chemically treated intertubular dentin exhibit high piezoelectric activity and can be visualized in PFM …

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Evidence For Two Kinematically Distinct Broad Emission Line Producing Regions In Active Galactic Nuclei, Stephanie A. Snedden, C. Martin Gaskell Nov 2006

Evidence For Two Kinematically Distinct Broad Emission Line Producing Regions In Active Galactic Nuclei, Stephanie A. Snedden, C. Martin Gaskell

C. Martin Gaskell Publications

We present the results of an analysis of line profiles of high- and low-ionization broad emission lines in 8 AGNs observed by the Hubble Space Telescope. We derive the physical conditions in the gas as a function of velocity. We find no evidence for a separate intermediate line region. For the broad line region as a whole we find a major contradiction between the velocity dependencies of conditions deduced from the major high-ionization lines and those deduced from the hydrogen lines alone if they are assumed to come from the same gas clouds. The hydrogen lines imply that the density …

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X-Ray/Ultraviolet Observing Campaign Of The Markarian 279 Active Galactic Nucleus Outflow: A Close Look At The Absorbing/Emitting Gas With Chandra-Letgs, E. Constantini, Jelle S. Kaastra, Nahum Arav, Gerard A. Kriss, K.C. Steenbrugge, Jack R. Gabel, F. Verbunt, Ehud Behar, C. Martin Gaskell, Kirk T. Korista, Daniel Proga, Jessica Kim-Quijano, J.E. Scott, Elizabeth S. Klimek, C.H. Hedrick Nov 2006

X-Ray/Ultraviolet Observing Campaign Of The Markarian 279 Active Galactic Nucleus Outflow: A Close Look At The Absorbing/Emitting Gas With Chandra-Letgs, E. Constantini, Jelle S. Kaastra, Nahum Arav, Gerard A. Kriss, K.C. Steenbrugge, Jack R. Gabel, F. Verbunt, Ehud Behar, C. Martin Gaskell, Kirk T. Korista, Daniel Proga, Jessica Kim-Quijano, J.E. Scott, Elizabeth S. Klimek, C.H. Hedrick

C. Martin Gaskell Publications

We present a Chandra-LETGS observation of the Seyfert 1 galaxy Mrk 279. This observation was carried out simultaneously with HST-STIS and FUSE, in the context of a multiwavelength study of this source. The Chandra pointings were spread over ten days for a total exposure time of ~360 ks. The maximal continuum flux variation is of the order of 30%. The spectrum of Mrk 279 shows evidence of broad emission features, especially at the wavelength of the O VII triplet. We quantitatively explore the possibility that this emission is produced in the broad line region (BLR). We modeled the broad …

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Nondipole Effects In Double Photoionization Of He, A.Y. Istomin, N. L. Manakov, A. V. Meremianin, Anthony F. Starace Nov 2006

Nondipole Effects In Double Photoionization Of He, A.Y. Istomin, N. L. Manakov, A. V. Meremianin, Anthony F. Starace

Anthony F. Starace Publications

Lowest-order nondipole effects are studied in double photoionization (DPI) of the He atom. Ah initio parametrizations of the quadrupole transition amplitude for DPI from the 1S0state are presented in terms of the exact two-electron reduced matrix elements. Parametrizations for the dipole-quadrupole triply differential cross section (TDCS) and doubly differential cross section (DDCS) are presented in terms of polarization-independent amplitudes for the case of an elliptically polarized photon. Expressions for the DDCS in terms of the reduced two-electron matrix elements are also given. A general analysis of retardation-induced asymmetries of the TDCS including the circular dichroism effect at …

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Measurement Of The Cp-Violation Parameter Of B0 Mixing And Decay With Pp̅ → ΜμX Data, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Nov 2006

Measurement Of The Cp-Violation Parameter Of B0 Mixing And Decay With Pp̅ → ΜμX Data, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We measure the dimuon charge asymmetry A in pp̅ collisions at a center of mass energy √s =1960 GeV. The data was recorded with the D0 detector and corresponds to an integrated luminosity of approximately 1:0 fb-1. Assuming that the asymmetry A is due to asymmetric B0 ↔ B̅ mixing and decay, we extract the CP-violation parameter of B0 mixing and decay: [ℜ(∊B0)]/[1+∣∊B0∣2 = (AB0)/4 = -0.0023 ± 0.0011 (stat) ± 0.0008(syst). AB0 is the dimuon charge asymmetry from decays of B …

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Threshold Effects In Strong-Field Detachment Of H- And F-: Plateau Enhancements And Angular Distribution Variations, Katarzyna Krajewska, Ilya I. Fabrikant, Anthony F. Starace Nov 2006

Threshold Effects In Strong-Field Detachment Of H- And F-: Plateau Enhancements And Angular Distribution Variations, Katarzyna Krajewska, Ilya I. Fabrikant, Anthony F. Starace

Anthony F. Starace Publications

Above-threshold detachment (ATD) rates for H1 and F1 ions in the high-energy plateau region are calculated as functions of photon number and laser intensity by solving the time-dependent Schrödinger equation within the Sturmian-Floquet approach. Pronounced enhancements of the ATD rates are found (up to an order of magnitude) as the laser-field intensity passes across ponderomotive-potential-induced channel closings. We confirm the zero-range potential model results of Borca et al. [Phys. Rev. Lett. 88, 193001 (2002)] for negative ions whose initial states have s symmetry, and we investigate here the case of initial states having p symmetry. Depending on …

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Experimental Observation Of Nonlinear Thomson Scattering, Szu-Yuan Chen, Anatoly Maksimchuk, Donald Umstadter Nov 2006

Experimental Observation Of Nonlinear Thomson Scattering, Szu-Yuan Chen, Anatoly Maksimchuk, Donald Umstadter

Donald Umstadter Publications

A century ago, J. J. Thomson showed that the scattering of low-intensity light by electrons was a linear process (i.e., the scattered light frequency was identical to that of the incident light) and that light’s magnetic field played no role. To- day, with the recent invention of ultra-high-peak- power lasers it is now possible to create a sufficient photon density to study Thomson scattering in the relativistic regime. With increasing light intensity, electrons quiver during the scattering process with increasing velocity, approaching the speed of light when the laser intensity approaches 1018 W/cm2. In this limit, the …

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Fluorescence Polarization Of Helium Negative-Ion Resonances Excited By Polarized Electron Impact, J. W. Maseberg, Timothy J. Gay Nov 2006

Fluorescence Polarization Of Helium Negative-Ion Resonances Excited By Polarized Electron Impact, J. W. Maseberg, Timothy J. Gay

Timothy J. Gay Publications

We have investigated helium (1s3d) 3D → (1s2p) 3P (588 nm) fluorescence produced by electron impact excitation in the vicinity of the (2s22p) 2P and (2s2p2) 2D negative-ion resonances at 57.2 and 58.3 eV, respectively. In contrast to previous work, we use spin-polarized incident electrons and report the relative Stokes parameters P1, P2, and P3 in the 55–60 eV region. Our failure to see discernable resonance effects in P2 indicates that even though the lifetime of these resonances is significant (~10 fs), magnetic forces acting on …

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Production Of Excited Atomic Hydrogen And Deuterium From H2 And D2 Photodissociation, J. D. Bozek, J. E. Furst, Timothy J. Gay, H. Gould, A. L. D. Kilcoyne, J. R. Machacek, F. Martin, K. W. Mclaughlin, J. L. Sanz-Vicario Nov 2006

Production Of Excited Atomic Hydrogen And Deuterium From H2 And D2 Photodissociation, J. D. Bozek, J. E. Furst, Timothy J. Gay, H. Gould, A. L. D. Kilcoyne, J. R. Machacek, F. Martin, K. W. Mclaughlin, J. L. Sanz-Vicario

Timothy J. Gay Publications

We have measured the production of both Lyα and Hα fluorescence from atomic H and D for the photodissociation of H2 and D2 by linearly polarized photons with energies between 24 and 60 eV. In this energy range, excited photofragments result primarily from the production of doubly excited molecular species which promptly autoionize or dissociate into two neutrals. Our data are compared with ab initio calculations of the dissociation process, in which both doubly excited state production and prompt ionization (non resonant) channels are considered. Agreement between our experimental data and that of earlier work, and with our …

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Electronic Structure And Polymerization Of A Self-Assembled Monolayer With Multiple Arene Rings, D.Q. Feng, David Wisbey, Yaroslav B. Losovyj, Y. Tai, M. Zharnikov, Peter A. Dowben Oct 2006

Electronic Structure And Polymerization Of A Self-Assembled Monolayer With Multiple Arene Rings, D.Q. Feng, David Wisbey, Yaroslav B. Losovyj, Y. Tai, M. Zharnikov, Peter A. Dowben

Peter Dowben Publications

We find evidence of intermolecular interactions for a self-assembled monolayer (SAM) formed from a large molecular adsorbate, [1,1′;4′,1′′-terphenyl]-4,4′′-dimethanethiol, from the dispersion of the molecular orbitals with changing wave vector k. With the formation self-assembled molecular (SAM) layer, the molecular orbitals hybridize to electronic bands, with indications of significant band dispersion of the unoccupied molecular orbitals. The electronic structure is also seen to be dependent upon temperature, and cross linking between the neighbor molecules, indicating that the electronic structure may be subtly altered by changes in molecular conformation and packing.

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Search For Pair Production Of Scalar Bottom Quarks In Pp̅ Collisions At √S =1:96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Oct 2006

Search For Pair Production Of Scalar Bottom Quarks In Pp̅ Collisions At √S =1:96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

A search for direct production of scalar bottom quarks (b̃) is performed with 310 pb-1 of data collected by the D0 experiment in pp̅ collisions at √s = 1.96 TeV at the Fermilab Tevatron Collider. The topology analyzed consists of two b jets and an imbalance in transverse momentum due to undetected neutralinos (χ̃10), with χ̃10 assumed to be the lightest supersymmetric particle. We find the data consistent with standard model expectations, and set a 95% C.L. exclusion domain in the (mb̃, m χ̃10) mass plane, …

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Application Of Coulomb Wave Function Discrete Variable Representation To Atomic Systems In Strong Laser Fields, Liang-You Peng, Anthony F. Starace Oct 2006

Application Of Coulomb Wave Function Discrete Variable Representation To Atomic Systems In Strong Laser Fields, Liang-You Peng, Anthony F. Starace

Anthony F. Starace Publications

We present an efficient and accurate grid method for solving the time-dependent Schrödinger equation for an atomic system interacting with an intense laser pulse. Instead of the usual finite difference (FD) method, the radial coordinate is discretized using the discrete variable representation (DVR) constructed from Coulomb wave functions. For an accurate description of the ionization dynamics of atomic systems, the Coulomb wave function discrete variable representation (CWDVR) method needs three to ten times fewer grid points than the FD method. The resultant grid points of the CWDVR are distributed unevenly so that one has a finer grid near the origin …

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Search For Neutral, Long-Lived Particles Decaying Into Two Muons In Pp̅ Collisions At √S = 1:96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Oct 2006

Search For Neutral, Long-Lived Particles Decaying Into Two Muons In Pp̅ Collisions At √S = 1:96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We present a search for a neutral particle, pair produced in pp̅ collisions at√s = 1.96 TeV, which decays into two muons and lives long enough to travel at least 5 cm before decaying. The analysis uses ≈ 380 pb-1 of data recorded with the D0 detector. The background is estimated to be about one event. No candidates are observed, and limits are set on the pair-production cross section times branching fraction into dimuons + X for such particles. For a mass of 10 GeVand lifetime of 4 × 10-11 s, we exclude values greater than 0.14 pb …

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Search For The Standard Model Higgs Boson In The Pp̅→ Zh → Νν̅Bb̅ Channel, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Oct 2006

Search For The Standard Model Higgs Boson In The Pp̅→ Zh → Νν̅Bb̅ Channel, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We report a search for the standard model (SM) Higgs boson based on data collected by the D0 experiment at the Fermilab Tevatron Collider, corresponding to an integrated luminosity of 260 pb-1. We study events with missing transverse energy and two acoplanar b jets, which provide sensitivity to the ZH production cross section in the νν̅bb̅ channel, and to WH production when the lepton from the W → ℓν decay is undetected. The data are consistent with the SM background expectation, and we set 95% C.L. upper limits on σ(pp̅ → ZH/WH) × …

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Observation Of Relativistic Cross-Phase Modulation In High-Intensity Laser-Plasma Interactions, Shouyuan Chen, Matthew Rever, P. Zhang, W. Theobald, Donald Umstadter Oct 2006

Observation Of Relativistic Cross-Phase Modulation In High-Intensity Laser-Plasma Interactions, Shouyuan Chen, Matthew Rever, P. Zhang, W. Theobald, Donald Umstadter

Donald Umstadter Publications

A nonlinear optical phenomenon, relativistic cross-phase modulation, is reported. A relativistically intense light beam (I=1.3×1018 W cm-2, λ =1.05 μm) is experimentally observed to cause phase modulation of a lower intensity, copropagating light beam in a plasma. The latter beam is generated when the former undergoes the stimulated Raman forward scattering instability. The bandwidth of the Raman satellite is found to be broadened from 3.8–100 nm when the pump laser power is increased from 0.45–2.4 TW. A signature of relativistic cross-phase modulation, namely, asymmetric spectral broadening of the Raman signal, is observed at a pump …

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Measurement Of The Inclusive Jet Cross Section In Pp̅ Interactions At √S = 1:96 Tev Using A Cone-Based Jet Algorithm, A. Abulencia, Kenneth A. Bloom, Cdf Collaboration Oct 2006

Measurement Of The Inclusive Jet Cross Section In Pp̅ Interactions At √S = 1:96 Tev Using A Cone-Based Jet Algorithm, A. Abulencia, Kenneth A. Bloom, Cdf Collaboration

Kenneth Bloom Publications

We present a measurement of the inclusive jet cross section in pp̅ interactions at √s = 1:96 TeV using 385 pb-1 of data collected with the CDF II detector at the Fermilab Tevatron. The results are obtained using an improved cone-based jet algorithm (Midpoint). The data cover the jet transverse momentum range from 61 to 620 GeV/c, extending the reach by almost 150 GeV/c compared with previous measurements at the Tevatron. The results are in good agreement with next-to-leading order perturbative QCD predictions using the CTEQ6.1M parton distribution functions.

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Remote Bond Breaking By Interacting Temporary Anion States, Paul Burrow, Gordon A. Gallup Oct 2006

Remote Bond Breaking By Interacting Temporary Anion States, Paul Burrow, Gordon A. Gallup

Gordon Gallup Publications

The cross section for bond breaking at the site of a dissociative temporary negative ion state through the dissociative electron attachment process can be considerably enhanced by the presence of a second longer-lived temporary negative ion state elsewhere in the molecule, even one quite remote from the first. In a series of chloroalkenes possessing both C–Cl and C=C bonds separated by various distances, we show that the cross sections are determined by the lifetime of the lower anion state created by the mixing of the anion states of these two moieties, with the wave function’s coefficients giving the probability that …

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Remote Bond Breaking By Interacting Temporary Anion States, Paul Burrow, Gordon A. Gallup Oct 2006

Remote Bond Breaking By Interacting Temporary Anion States, Paul Burrow, Gordon A. Gallup

Paul Burrow Publications

The cross section for bond breaking at the site of a dissociative temporary negative ion state through the dissociative electron attachment process can be considerably enhanced by the presence of a second longer-lived temporary negative ion state elsewhere in the molecule, even one quite remote from the first. In a series of chloroalkenes possessing both C–Cl and C=C bonds separated by various distances, we show that the cross sections are determined by the lifetime of the lower anion state created by the mixing of the anion states of these two moieties, with the wave function’s coefficients giving the probability that …

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