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2004

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Articles 61 - 90 of 609

Full-Text Articles in Physics

The Origin Of Fe Ii Emission In Active Galactic Nuclei, J. A. Baldwin, Gary J. Ferland, K. T. Korista, F. Hamann, A. Lacluyzé Nov 2004

The Origin Of Fe Ii Emission In Active Galactic Nuclei, J. A. Baldwin, Gary J. Ferland, K. T. Korista, F. Hamann, A. Lacluyzé

Physics and Astronomy Faculty Publications

We used a very large set of models of broad emission line region (BELR) clouds in active galactic nuclei to investigate the formation of the observed Fe II emission lines. We show that photoionized BELR clouds cannot produce both the observed shape and observed equivalent width of the 2200-2800 Å Fe II UV bump unless there is considerable velocity structure corresponding to a microturbulent velocity parameter vturb≥100 km s-1 for the locally optimally emitting cloud models used here. This could be either microturbulence in gas that is confined by some phenomenon such as MHD waves or a …

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Geometric Acoustic Modeling Of The Lds Conference Center, Heather Smith Nov 2004

Geometric Acoustic Modeling Of The Lds Conference Center, Heather Smith

Theses and Dissertations

This thesis discusses the process of modeling a 21,000 seat fan-shaped auditorium using methods of geometric acoustics. Two commercial geometric acoustics software packages were used in the research: CATT-Acoustic™ 8.0 and EASE™ 4.1. The process first included creating preliminary models of the hall using published absorption coefficients for its surfaces and approximate scattering coefficients based on current best-known techniques. A detailed analysis determined the minimum numbers of rays needed in both packages to produce reliable results with these coefficient values. It was found that 100,000 rays were needed for CATT™ and 500,000 rays were needed for EASE™. Analysis was also …

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Theoretical Study Of The Magnetic Ordering In Rare-Earth Compounds With Face-Centered-Cubic Structure, Chun-Gang Duan, Renat F. Sabirianov, Jianjun Liu, Wai-Ning Mei, Peter A. Dowben, John R. Hardy Nov 2004

Theoretical Study Of The Magnetic Ordering In Rare-Earth Compounds With Face-Centered-Cubic Structure, Chun-Gang Duan, Renat F. Sabirianov, Jianjun Liu, Wai-Ning Mei, Peter A. Dowben, John R. Hardy

Peter Dowben Publications

We present a detailed theoretical study of the magnetic ordering in heavy rare-earth compounds with a face-centered-cubic structure. In addition to the exchange interactions which are counted up to the third nearest neighbors, the effect of the dipolar interactions and magnetic anisotropic effect are also included in our model Hamiltonian. The interactions parameters are obtained from first-principles band-structure calculations by fitting the total energies of different magnetic configurations to the Heisenberg Model. Thus from utilizing the Monte Carlo simulations, we explained the formation of different magnetic structures in the rare-earth compounds.

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Noncollinear Spin States And Competing Interactions In Half-Metals, Ralph Skomski, Jian Zhou, Peter A. Dowben, David J. Sellmyer Nov 2004

Noncollinear Spin States And Competing Interactions In Half-Metals, Ralph Skomski, Jian Zhou, Peter A. Dowben, David J. Sellmyer

Peter Dowben Publications

The high-field spin structure of magnetic perovskites and related magnetoresistive materials is investigated by model calculations. Competing exchange as well as real-structure-dependent random field, random anisotropy, and Dzyaloshinskii–Moriya interactions yield a noncollinear magnetic structure that may be called a spin colloid. The noncollinear structure, which contributes to the zero- and finite-temperature spin mixing and reduces the magnetoresistance, is strongly field dependent. © 2005 American Institute of Physics. [DOI: 10.1063/1.1851412]

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Disorder-Induced Depression Of The Curie Temperature In Mechanically Milled Gdal2, Marco Morales Torres, D. S. Williams, P. M. Shand, C. Stark, T. M. Pekarek, Lanping Yue, V. Petkov, Diandra Leslie-Pelecky Nov 2004

Disorder-Induced Depression Of The Curie Temperature In Mechanically Milled Gdal2, Marco Morales Torres, D. S. Williams, P. M. Shand, C. Stark, T. M. Pekarek, Lanping Yue, V. Petkov, Diandra Leslie-Pelecky

Diandra Leslie-Pelecky Publications

The effect of disorder on the ferromagnetic transition is investigated in mechanically milled GdAl2. GdAl2 is a ferromagnet when crystalline and a spin glass when amorphous. Mechanical milling progressively disorders the alloy, allowing observation of the change from ferromagnetic to a disordered magnetic state. X-ray diffraction and pair-distribution-function analysis are used to determine the grain size, lattice parameter, and mean-squared atomic displacements. The magnetization as a function of temperature is described by a Gaussian distribution of Curie temperatures. The mean Curie temperature decreases with decreasing lattice parameter, where lattice parameter serves as a measure of defect concentration. …

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A Geometrical Approach To N=2 Super Yang-Mills Theory On The Two Dimensional Lattice, Simon Catterall Nov 2004

A Geometrical Approach To N=2 Super Yang-Mills Theory On The Two Dimensional Lattice, Simon Catterall

Physics - All Scholarship

We propose a discretization of two dimensional Euclidean Yang-Mills theories with N=2 supersymmetry which preserves exactly both gauge invariance and an element of supersymmetry. The approach starts from the twisted form of the continuum super Yang Mills action which we show may be written in terms of two real Kahler-Dirac fields whose components transform into each other under the twisted supersymmetry. Once the theory is written in this geometrical language it is straightforward to discretize by mapping the component tensor fields to appropriate geometrical structures in the lattice and by replacing the continuum exterior derivative and its adjoint by appropriate …

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Direct Comparison Between Phase Locked Oscillator And Direct Resonance Oscillator In The Noncontact Atomic Force Microscopy Under Ultrahigh Vacuum, Byung I. Kim Nov 2004

Direct Comparison Between Phase Locked Oscillator And Direct Resonance Oscillator In The Noncontact Atomic Force Microscopy Under Ultrahigh Vacuum, Byung I. Kim

Physics Faculty Publications and Presentations

I have demonstrated the advantage of the phase locked oscillator (PLO) over the conventional direct resonance oscillator (DRO) in noncontact mode atomic force microscopy (AFM) under ultrahigh vacuum. Direct comparison between PLO and DRO has been made in terms of background noise level, temporal response, and stability. Compared to the DRO method without phase coherence, the experimental results show that the PLO method is more effective in reducing the noise level and enhancing the stability over all force regimes in UHV noncontact AFM. The noise reduction and stability enhancement in PLO indicate the important role of the phase coherent effect …

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Theoretical Study Of The Magnetic Ordering In Rare-Earth Compounds With Face-Centered-Cubic Structure, Chun-Gang Duan, Renat F. Sabirianov, Jianjun Liu, Wai-Ning Mei, Peter A. Dowben, John R. Hardy Nov 2004

Theoretical Study Of The Magnetic Ordering In Rare-Earth Compounds With Face-Centered-Cubic Structure, Chun-Gang Duan, Renat F. Sabirianov, Jianjun Liu, Wai-Ning Mei, Peter A. Dowben, John R. Hardy

Physics Faculty Publications

We present a detailed theoretical study of the magnetic ordering in heavy rare-earth compounds with a face-centered-cubic structure. In addition to the exchange interactions which are counted up to the third nearest neighbors, the effect of the dipolar interactions and magnetic anisotropic effect are also included in our model Hamiltonian. The interactions parameters are obtained from first-principles band-structure calculations by fitting the total energies of different magnetic configurations to the Heisenberg Model. Thus from utilizing the Monte Carlo simulations, we explained the formation of different magnetic structures in the rare-earth compounds.

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The Dynamics And Tuning Of Orchestral Crotales, Bradley M. Deutsch, Cherie L. Ramirez, Thomas R. Moore Nov 2004

The Dynamics And Tuning Of Orchestral Crotales, Bradley M. Deutsch, Cherie L. Ramirez, Thomas R. Moore

Student-Faculty Collaborative Research Publications

Crotales are center-weighted, tuned cymbals that are found in the percussion section of most orchestras. They are arranged like a keyboard in octave sets and are commercially available in two octaves, from C6 to C8. Little information about the physics of crotales has been reported in the literature, despite their having the interesting property of producing a particularly pleasing sound. In this study, the acoustic and vibrational properties of crotales from C6 to C8 are theoretically and experimentally investigated. Interferograms of typical vibrational modes are presented, and the frequencies of the acoustically important modes of crotales are identified and reported. …

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Light Hadrons With Improved Staggered Quarks: Approaching The Continuum Limit, James E. Hetrick, C. Aubin Nov 2004

Light Hadrons With Improved Staggered Quarks: Approaching The Continuum Limit, James E. Hetrick, C. Aubin

All Faculty Articles - School of Engineering and Computer Science

We have extended our program of QCD simulations with an improved Kogut-Susskind quark action to a smaller lattice spacing, approximately 0.09 fm. Also, the simulations with a ≈ 0.12 fm have been extended to smaller quark masses. In this paper we describe the new simulations and computations of the static quark potential and light hadron spectrum. These results give information about the remaining dependences on the lattice spacing. We examine the dependence of computed quantities on the spatial size of the lattice, on the numerical precision in the computations, and on the step size used in the numerical integrations. We …

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Light Pseudoscalar Decay Constants, Quark Masses, And Low Energy Constants From Three Flavor Lattice Qcd, James E. Hetrick, C. Aubin Nov 2004

Light Pseudoscalar Decay Constants, Quark Masses, And Low Energy Constants From Three Flavor Lattice Qcd, James E. Hetrick, C. Aubin

All Faculty Articles - School of Engineering and Computer Science

As part of our program of lattice simulations of three-flavor QCD with improved staggered quarks, we have calculated pseudoscalar meson masses and decay constants for a range of valence quark masses and sea-quark masses on lattices with lattice spacings of about 0.125 and 0.09 fm. We fit the lattice data to forms computed with “staggered chiral perturbation theory.” Our results provide a sensitive test of the lattice simulations, and especially of the chiral behavior, including the effects of chiral logarithms. We find: fπ = 129.5 ± 0.9 ± 3.5 MeV, fK = 156.6 ± 1.0 ± 3.6 MeV, and fK/ …

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The Effect Of Low Energy Electron And Uv/Vis Radiation Aging On The Electron Emission Properties And Breakdown Of Thin-Film Dielectrics, John R. Dennison, C. D. Thomson, Alec Sim Nov 2004

The Effect Of Low Energy Electron And Uv/Vis Radiation Aging On The Electron Emission Properties And Breakdown Of Thin-Film Dielectrics, John R. Dennison, C. D. Thomson, Alec Sim

All Physics Faculty Publications

Studies of secondary and backscattered electron yield curves of thin-film dielectrics have recently been made using pulsed, low current electron beam methods to minimize insulator charging. These capabilities have allowed us to investigate the evolution of surface and internal charge profiles as a function of low energy electron (keV) pulsed-electron fluence to determine how quickly insulators charge, and how this can affect subsequent electron emission properties. We have also studied critical incident electron energies that result in electrical breakdown of insulator materials and the effect of breakdown on subsequent emission, charging and conduction. The qualitative physics of such processes in …

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Transitions Into The Negative-Energy Dirac Continuum, P Krekora, Q Su, Rainer Grobe Nov 2004

Transitions Into The Negative-Energy Dirac Continuum, P Krekora, Q Su, Rainer Grobe

Faculty publications – Physics

We compare the predictions of the single-particle Dirac equation with quantum field theory for an electron subjected to a space and time dependent field. We demonstrate analytically and numerically that a transition into the negative-energy subspace predicted by the single-particle Dirac equation is directly associated with the degree of suppression of pair-production as described by quantum field theory. We show that the portion of the mathematical wave function that populates the negative-energy states corresponds to the difference between the positron spatial density for systems with and without an electron initially present.

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Two-Loop Bethe Logarithms For Higher Excited S Levels, Ulrich D. Jentschura Nov 2004

Two-Loop Bethe Logarithms For Higher Excited S Levels, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

Processes mediated by two virtual low-energy photons contribute quite significantly to the energy of hydrogenic S states. The corresponding level shift is of the order of ( α / π )2 ( Z α )6 mec2 and may be ascribed to a two-loop generalization of the Bethe logarithm. For 1 S and 2 S states, the correction has recently been evaluated by Pachucki and Jentschura [Phys. Rev. Lett. 91, 113005 (2003)]. Here, we generalize the approach to higher excited S states, which in contrast to the 1 S and 2 S states can decay to …

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Nucleation Rates Of Water And Heavy Water Using Equations Of State, Abdalla Obeidat, Jin-Song Li, Gerald Wilemski Nov 2004

Nucleation Rates Of Water And Heavy Water Using Equations Of State, Abdalla Obeidat, Jin-Song Li, Gerald Wilemski

Physics Faculty Research & Creative Works

The original formula of Gibbs for the reversible work of critical nucleus formation is evaluated in three approximate ways for ordinary and heavy water. The least approximate way employs an equation of state to evaluate the pressure difference between the new and old phases. This form of the theory yields a temperature dependence for the nucleation rate close to that observed experimentally. This is a substantial improvement over the most commonly used (and most approximate) form of classical theory.©2004 American Institute of Physics.

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Micro-Auger Electron Spectroscopy Studies Of Chemical And Electronic Effects At Gan-Sapphire Interfaces, X. L. Sun, S. T. Bradley, G. H. Jessen, David C. Look, Richard J. Molnar, L. J. Brillson Nov 2004

Micro-Auger Electron Spectroscopy Studies Of Chemical And Electronic Effects At Gan-Sapphire Interfaces, X. L. Sun, S. T. Bradley, G. H. Jessen, David C. Look, Richard J. Molnar, L. J. Brillson

Physics Faculty Publications

We have used cross-sectional micro-Auger electron spectroscopy (AES), coupled with micro-cathodoluminescence (CLS) spectroscopy, in a UHV scanning electron microscope to probe the chemical and related electronic features of hydride vapor phase epitaxy GaN/sapphire interfaces on a nanometer scale. AES images reveal dramatic evidence for micron-scale diffusion of O from Al2O3 into GaN. Conversely, plateau concentrations of N can extend microns into the sapphire, corresponding spatially to a 3.8 eV defect emission and Auger chemical shifts attributed to Al-N-O complexes. Interface Al Auger signals extending into GaN indicates AlGaN alloy formation, consistent with a blue-shifted CLS local interface …

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As-Doped P-Type Zno Produced By An Evaporation/Sputtering Process, David C. Look, G. M. Renlund, R. H. Burgener, J. R. Sizelove Nov 2004

As-Doped P-Type Zno Produced By An Evaporation/Sputtering Process, David C. Look, G. M. Renlund, R. H. Burgener, J. R. Sizelove

Physics Faculty Publications

Strongly p-type ZnO is produced by the following sequence of steps: (1) evaporation of Zn3As2 on a fused-quartz substrate at 350 °C; and (2) sputtering of ZnO with substrate held at 450 °C. The electrical characteristics include: resistivity of 0.4 Ω cm, a mobility of 4 cm2∕V s, and a hole concentration of about 4×1018 cm−3. This resistivity is among the best (lowest) ever reported for p-type ZnO. Secondary-ion mass spectroscopic analysis gives an average As concentration about 5×1019 cm−3, and a simple one-band fit of the …

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Relaxation To Native Conformation Of A Bond-Fluctuating Protein Chain With Hydrophobic And Polar Nodes, Johan Bjursell, Ras B. Pandey Nov 2004

Relaxation To Native Conformation Of A Bond-Fluctuating Protein Chain With Hydrophobic And Polar Nodes, Johan Bjursell, Ras B. Pandey

Faculty Publications

The conformation and dynamics of a protein chain with hydrophobic and polar nodes are examined by the bond-fluctuation model using Monte Carlo simulations on a cubic lattice. The minimal (nearest neighbor) interaction leads to standard (self-avoiding walk) conformation, i.e., the scaling of the radius of gyration Rg with the molecular weight N Rg ∝ Nγ with γ ≃ 3/5/ Specific interactions with longer range and higher strength are needed to approach the native globular conformations with γ < 3/5. Relaxation into the globular ground state shows a weak power-law decay, i.e., Rg ∝ t-α, α ~ 0.06-0.12.

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Comparison Of Auto-Adjusting And Fixed Level Continuous Positive Airway Pressure Therapy In Patients With Mild To Moderate Obstructive Sleep Apnoea Hypopnoea Syndrome, Geraldine Nolan Nov 2004

Comparison Of Auto-Adjusting And Fixed Level Continuous Positive Airway Pressure Therapy In Patients With Mild To Moderate Obstructive Sleep Apnoea Hypopnoea Syndrome, Geraldine Nolan

Masters

Obstructive Sleep Apnoea Hypopnoea syndrome (OSAHS) is a potentially serious medical disorder associated with increased morbidity and mortality. It is estimated to affect 4% of males and 2% of females between the ages of forty and sixty. Nasal continuous positive airway pressure (CPAP) is the first choice treatment for this condition and it is extremely effective at controlling OSAHS. However, not all patients can tolerate this therapy, in particular those within the mild to moderate category, and there are also many others who are unable to comply with the minimum usage requirements of at least four hours every night. A …

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Complex Multiplication Of Exactly Solvable Calabi-Yau Varieties, Monika Lynker, Rolf Schimmrigk, Steven Stewart Nov 2004

Complex Multiplication Of Exactly Solvable Calabi-Yau Varieties, Monika Lynker, Rolf Schimmrigk, Steven Stewart

Faculty Articles

We propose a conceptual framework that leads to an abstract characterization for the exact solvability of Calabi–Yau varieties in terms of abelian varieties with complex multiplication. The abelian manifolds are derived from the cohomology of the Calabi–Yau manifold, and the conformal field theoretic quantities of the underlying string emerge from the number theoretic structure induced on the varieties by the complex multiplication symmetry. The geometric structure that provides a conceptual interpretation of the relation between geometry and conformal field theory is discrete, and turns out to be given by the torsion points on the abelian varieties.

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Surface Structure Of Ultrathin Copolymer Films Of Ferroelectric Vinylidene Fluoride (70%) With Trifluoroethylene (30%) On Graphite, Lei Cai, Hongwei Qu, Chenxi Lu, Stephen Ducharme, Peter A. Dowben, Jiandi Zhang Oct 2004

Surface Structure Of Ultrathin Copolymer Films Of Ferroelectric Vinylidene Fluoride (70%) With Trifluoroethylene (30%) On Graphite, Lei Cai, Hongwei Qu, Chenxi Lu, Stephen Ducharme, Peter A. Dowben, Jiandi Zhang

Department of Physics and Astronomy: Faculty Publications

The structure and local structural distortions, through the polarization manipulation, of crystalline films of ferroelectric vinylidene fluoride (70%) with trifluoroethylene (30%) [P(VDF-TrFE)] copolymer on graphite were studied by scanning tunneling microscopy (STM). A quasispiral twist in C[Single Bond]C bonds with rotations about the polymer chain axis was observed by high-resolution STM, indicating a surface relaxation of the strained copolymer films. Such a relaxation behavior appears to be linked to the observed local dipole rotations accompanied by the reversal of the local polarization with biasing the STM tip. A structure model is proposed based upon the observations

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Computing The M = 1 Diocotron Frequency Via An Equilibrium Calculation In Non-Neutral Plasmas, Ross L. Spencer Oct 2004

Computing The M = 1 Diocotron Frequency Via An Equilibrium Calculation In Non-Neutral Plasmas, Ross L. Spencer

Faculty Publications

The m = 1 diocotron mode in non-neutral plasmas has long been thought of as a shifted equilibrium, and its frequency has been approximately calculated in this way by Fine and Driscoll [Phys. Plasmas 5, 601 (1998)]. This article shows that this idea can be coupled with a standard axisymmetric equilibrium calculation on a grid to calculate the frequency of this mode to very high precision including both finite-length and thermal effects, provided that the Debye length is small enough. As the Debye length begins to approach the plasma size not only does the shifted equilibrium calculation fail to predict …

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Direct Photon Cross Section With Conversions At Cdf, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Oct 2004

Direct Photon Cross Section With Conversions At Cdf, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a measurement of the isolated direct photon cross section in pp̅ collisions at √s =1.8 TeV and |η|0→γγ and η→γγ events from the data we use a new background subtraction technique which takes advantage of the tracking information available in a photon conversion event. We find that the shape of the cross section as a function of photon pT is poorly described by next-to-leading-order QCD predictions, but agrees with previous CDF measurements.

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Controlling Dissociative Adsorption For Effective Growth Of Carbon Nanotubes, Vijaya Kayastha, Yoke Khin Yap, Svetlana Dimovski, Yury Gogotsi Oct 2004

Controlling Dissociative Adsorption For Effective Growth Of Carbon Nanotubes, Vijaya Kayastha, Yoke Khin Yap, Svetlana Dimovski, Yury Gogotsi

Department of Physics Publications

Dissociative adsorption has been widely simplified as part of the vapor–liquid–solid (VLS) growth model. We found that the addition of specific carrier gases can critically modify the growth rate and growth density of multiwall carbon nanotubes (MWNTs). These results were explained by dissociative adsorption of C2H2 molecules and a solid-core VLS growth model. Based on these integrated mechanisms, vertically aligned MWNTs were grown with an initial growth rate as high as ∼800μm∕h. This efficient growth process results at temperature and C2H2 partial pressures at which the decomposition and segregation rates of carbon are balanced. …

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Ferroelectric Nanomesa Formation From Polymer Langmuir-Blodgett Films, Mengjun Bai, Stephen Ducharme Oct 2004

Ferroelectric Nanomesa Formation From Polymer Langmuir-Blodgett Films, Mengjun Bai, Stephen Ducharme

Stephen Ducharme Publications

We report the fabrication and characterization of nanoscale ferroelectric structures consisting of disk-shaped nanomesas averaging 8.7±0.4 nm in height and 95±22 nm in diameter, and nanowells 9.8±3.3 nm in depth and 128±37 nm in diameter, formed from Langmuir–Blodgett films of vinylidene fluoride copolymers after annealing in the paraelectric phase. The nanomesas retain the ferroelectric properties of the bulk material and so may be suitable for use in high-density nonvolatile random-access memories, acoustic transducer arrays, or infrared imaging arrays. The nanomesa and nanowell patterns may provide useful templates for nanoscale molding or contact-printing.

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Mechanisms And Dynamics Of The Metastable Decay In Ar-2(+), J. Fedor, K. Gluch, R. Parajuli, S. Matt-Leubner, Olof E. Echt, P. Scheier, T. D. Mark Oct 2004

Mechanisms And Dynamics Of The Metastable Decay In Ar-2(+), J. Fedor, K. Gluch, R. Parajuli, S. Matt-Leubner, Olof E. Echt, P. Scheier, T. D. Mark

Physics & Astronomy

A detailed experimental as well as theoretical investigation of the properties of the metastable dissociation Ar-2(+)-->Ar++Ar is presented. The mass-analyzed ion kinetic energy (MIKE) scan technique has been performed using a three sector field mass spectrometer. The possible mechanisms of the metastability of Ar-2(+) have been examined and the observed decay process is assigned to the II(1/2)(u)-->I(1/2)(g) bound to continuum radiative transition, in agreement with earlier work. The calculation of the theoretical shape of the kinetic energy release distribution of fragment ions allowed us to construct the theoretical MIKE peak and compare it with the raw experimental data. …

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Observation And Properties Of The X(3872) Decaying To J/Ψπ+Π- In Pp̅ Collisions At √S = 1.96 Tev, V. M. Abazov, Gregory R. Snow, D0 Collaboration Oct 2004

Observation And Properties Of The X(3872) Decaying To J/Ψπ+Π- In Pp̅ Collisions At √S = 1.96 Tev, V. M. Abazov, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

We report the observation of the X(3872) in the J/ψπ+π- channel, with J/ψ decaying to μ+μ-, in pp̅ collisions at √s = 1.96 TeV. Using approximately 230 pb-1 of data collected with the Run II D0 detector, we observe 522 ± 100 X(3872) candidates. The mass difference between the X(3872) state and the J=J/ψ is measured to be 774.9 ± 3.1(stat) ± 3.0(syst) MeV/c2. We have investigated the production and decay characteristics of the X(3872) and find them to be …

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Underlying Event In Hard Interactions At The Fermilab Tevatron P̅P Collider, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Oct 2004

Underlying Event In Hard Interactions At The Fermilab Tevatron P̅P Collider, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

For comparison of inclusive jet cross sections measured at hadron-hadron colliders to next-to-leading order (NLO) parton-level calculations, the energy deposited in the jet cone by spectator parton interactions must first be subtracted. The assumption made at the Tevatron is that the spectator parton interaction energy is similar to the ambient level measured in minimum bias events. In this paper, we test this assumption by measuring the ambient charged track momentum in events containing large transverse energy jets at √s =1800 GeV and √s =630 GeV and comparing this ambient momentum with that observed both in minimum bias events and with …

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Measurement Of Beauty Production In Deep Inelastic Scattering At Hera, S. Chekanov, M. Derrick, J. H. Loizides, S. Magill, S. Miglioranzi, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, A. Montanari, R. Nania, F. Palmonari, A. Pesci, L. Rinaldi Oct 2004

Measurement Of Beauty Production In Deep Inelastic Scattering At Hera, S. Chekanov, M. Derrick, J. H. Loizides, S. Magill, S. Miglioranzi, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, A. Montanari, R. Nania, F. Palmonari, A. Pesci, L. Rinaldi

Faculty Publications

The beauty production cross section for deep inelastic scattering events with at least one hard jet in the Breit frame together with a muon has been measured, for photon virtualities Q2>2 GeV2, with the ZEUS detector at HERA using integrated luminosity of 72 pb-1. The total visible cross section is σbb̄(ep→e jet μX)=40.9±5.7(stat.)-4.4+6. 0(syst.) pb. The next-to-leading order QCD prediction lies about 2.5 standard deviations below the data. The differential cross sections are in general consistent with the NLO QCD predictions; however at low values of Q2, Bjorken x, and muon transverse momentum, and high values of jet transverse …

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Optical Properties And Application Of Uranium-Based Thin Films For The Extreme Ultraviolet And Soft X-Ray Region, Richard L. Sandberg, David D. Allred, Shannon Lunt, Marie K. Urry, R. Steven Turley Oct 2004

Optical Properties And Application Of Uranium-Based Thin Films For The Extreme Ultraviolet And Soft X-Ray Region, Richard L. Sandberg, David D. Allred, Shannon Lunt, Marie K. Urry, R. Steven Turley

Faculty Publications

Uranium oxide and uranium nitride thin films reflect significantly more than all previously known/standard reflectors (e.g., nickel, gold, and iridium) for most of the 4-10 nm range at low angles of incidence. This work includes measurements of the EUV/soft x-ray (2-20 nm) reflectance of uranium-based thin films (~20 nm thick) and extraction of their optical constants (d and ?). We report the reflectances at 5, 10, and 15 degrees grazing incidence of air-oxidized sputtered uranium, reactively sputtered (O2) uranium oxide, and reactively sputtered (N2) uranium nitride thin films measured at Beamline 6.3.2 at the Advanced Light Source (ALS) at Lawrence …

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