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1997

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Articles 1 - 30 of 284

Full-Text Articles in Physics

Observation Of The Plasma Channel Dynamics And Coulomb Explosion In The Interaction Of A High-Intensity Laser Pulse With A He Gas Jet, G.S. Sarkisov, V. Yu. Bychenkov, V.T. Tikhonchuk, Anatoly Maksimchuk, Shouyuan Chen, R. Wagner, G. Mourou, Donald P. Umstadter Dec 1997

Observation Of The Plasma Channel Dynamics And Coulomb Explosion In The Interaction Of A High-Intensity Laser Pulse With A He Gas Jet, G.S. Sarkisov, V. Yu. Bychenkov, V.T. Tikhonchuk, Anatoly Maksimchuk, Shouyuan Chen, R. Wagner, G. Mourou, Donald P. Umstadter

Donald Umstadter Publications

We report the first interferometric observations of the dynamics of electron–ion cavitation of relativistically self-focused intense 4 TW, 400 fs laser pulse in a He gas jet. The electron density in a channel 1 mm long and 30 mm in diameter drops by a factor of approximately 10 from the maximum value of ~8x1019 cm23. A high radial velocity of the plasma expansion, ~3.8x108 cm/s, corresponding to an ion energy of about 300 keV, is observed. The total energy of fast ions is estimated to be 6% of the laser pulse energy. The high-velocity radial plasma …

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Global Energetic Neutral Atom (Ena) Measurements And Their Association With The Dst Index, A. M. Jorgensen, Harlan E. Spence, M. G. Henderson, G. D. Reeves, M. Sugiura, T. Kamei Dec 1997

Global Energetic Neutral Atom (Ena) Measurements And Their Association With The Dst Index, A. M. Jorgensen, Harlan E. Spence, M. G. Henderson, G. D. Reeves, M. Sugiura, T. Kamei

Physics & Astronomy

We present a new global magnetospheric index that measures the intensity of the Earth's ring current through energetic neutral atoms (ENAs). We have named it the Global Energetic Neutral Index (GENI), and it is derived from ENA measurements obtained by the Imaging Proton Spectrometer (IPS), part of the Comprehensive Energetic Particle and Pitch Angle Distribution (CEPPAD) experiment on the POLAR satellite. GENI provides a simple orbit-independent global sum of ENAs measured with IPS. Actual ENA measurements for the same magnetospheric state look different when seen from different points in the POLAR orbit. In addition, the instrument is sensitive …

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Nanoscale Imaging Of Domain Dynamics And Retention In Ferroelectric Thin Films, Alexei Gruverman, H. Tokumoto, A. S. Prakash, S. Aggarwal, B. Yang, M. Wuttig, R. Ramesh, O. Auciello, T. Venkatesan Dec 1997

Nanoscale Imaging Of Domain Dynamics And Retention In Ferroelectric Thin Films, Alexei Gruverman, H. Tokumoto, A. S. Prakash, S. Aggarwal, B. Yang, M. Wuttig, R. Ramesh, O. Auciello, T. Venkatesan

Alexei Gruverman Publications

We report results on the direct observation of the microscopic origins of backswitching in ferroelectric thin films. The piezoelectric response generated in the film by a biased atomic force microscope tip was used to obtain static and dynamic piezoelectric images of individual grains in a polycrystalline material. We demonstrate that polarization reversal occurs under no external field (i.e., loss of remanent polarization) via a dispersive continuous-time random walk process, identified by a stretched exponential decay of the remanent polarization.

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Hyperfine Splitting Of Low-Lying Heavy Baryons, Joseph Schechter, Masayasu Harada, Asif Qamar, Francesco Sannino, Herbert Weigel Dec 1997

Hyperfine Splitting Of Low-Lying Heavy Baryons, Joseph Schechter, Masayasu Harada, Asif Qamar, Francesco Sannino, Herbert Weigel

Physics - All Scholarship

We calculate the next-to-leading order contribution to the masses of the heavy baryons in the bound state approach for baryons containing a heavy quark. These 1/N_C corrections arise when states of good spin and isospin are generated from the background soliton of the light meson fields. Our study is motivated by the previously established result that light vector meson fields are required for this soliton in order to reasonably describe the spectrum of both the light and the heavy baryons. We note that the inclusion of light vector mesons significantly improves the agreement of the predicted hyperfine splitting with experiment. …

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Phase Structure Of Dynamical Triangulation Models In Three Dimensions, Simon Catterall, Ray L. Renken, John B. Kogut Dec 1997

Phase Structure Of Dynamical Triangulation Models In Three Dimensions, Simon Catterall, Ray L. Renken, John B. Kogut

Physics - All Scholarship

The dynamical triangulation model of three-dimensional quantum gravity is shown to have a line of transitions in an expanded phase diagram which includes a coupling mu to the order of the vertices. Monte Carlo renormalization group and finite size scaling techniques are used to locate and characterize this line. Our results indicate that for mu < mu1 ~ -1.0 the model is always in a crumpled phase independent of the value of the curvature coupling. For mu < 0 the results are in agreement with an approximate mean field treatment. We find evidence that this line corresponds to first order transitions extending to positive mu. However, the behavior appears to change for mu > mu2 ~ 2-4. The simplest scenario that is consistent with the data is the existence of a critical end point.

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Remark On The Potential Function Of The Linear Sigma Model, Joseph Schechter, David Delphenich Dec 1997

Remark On The Potential Function Of The Linear Sigma Model, Joseph Schechter, David Delphenich

Physics - All Scholarship

It is shown that the potential functions for the ordinary linear sigma model can be divided into two topographically different types depending on whether the quantity R\equiv (m_\sigma /m_\pi)^2 is greater than or less than nine. Since the Wigner-Weyl mode (R=1) and the Nambu-Goldstone mode (R=\infty belong to different regions, we speculate that this classification may provide a generalization to the broken symmetry situation, which could be convenient for roughly characterizing different possible applications of the model. It is noted that a more complicated potential does not so much change this picture as add different new regions.

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Measurement Of The Decay Amplitudes And Branching Fractions Of B → J/Ψ K* And B → J/Ψ K Decays, C. P. Jessop, Kenneth A. Bloom, Cleo Collaboration Dec 1997

Measurement Of The Decay Amplitudes And Branching Fractions Of B → J/Ψ K* And B → J/Ψ K Decays, C. P. Jessop, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

Using data taken with the CLEO II detector at the Cornell Electron Storage Ring, we present the first full angular analysis in the color-suppressed modes B0 → J/Ψ K *0and B0 → J/Ψ K*+. This leads to a complete determination of the decay amplitudes of these modes including the longitudinal polarization ΓL/Γ= 0.52 ± 0.07 ± 0.04 and the P wave component │P│2= 0.16 ± 0.08 ± 0.04. In addition, we update the branching fractions for B → J/Ψ K and B → J/Ψ K …

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Stern-Gerlach Effect For Electron Beams, Herman Batelaan, Timothy J. Gay, J. J. Schwendiman Dec 1997

Stern-Gerlach Effect For Electron Beams, Herman Batelaan, Timothy J. Gay, J. J. Schwendiman

Timothy J. Gay Publications

The conflict between Bohr’s assertion that the magnetic moment of the electron cannot be measured with experiments based on the concept of classical trajectories, and the measurement of the magnetic moment of electrons in a modified Penning trap by Dehmelt et al. has led us to reevaluate other implications of Bohr’s assertion. We show that, contrary to the analysis of Bohr and Pauli, the assumption of classical trajectories in a Stern-Gerlach–like device can result in a high degree of spin separation for an electron beam. This effect may persist within a fully quantum-mechanical analysis. The magnetic fields considered are such …

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"Hands-On" Epicycles And Retrograde Motion, Matthew J. Moelter, Bernard A. Bates Dec 1997

"Hands-On" Epicycles And Retrograde Motion, Matthew J. Moelter, Bernard A. Bates

Physics

No abstract provided.

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Electron-Impact Total Ionization Cross Sections Of Ch And C2H2, Yong-Ki Kim, M. Asgar Ali, M. Eugene Rudd Dec 1997

Electron-Impact Total Ionization Cross Sections Of Ch And C2H2, Yong-Ki Kim, M. Asgar Ali, M. Eugene Rudd

M. Eugene Rudd Publications

Electron-impact total ionization cross sections for the CH radical and C2H2 (acetylene) have been calculated using the Binary-Encounter-Bethe (BEB) model. The BEB model combines the Mott cross section and the asymptotic form of the Bethe theory, and has been shown to generate reliable ionization cross sections for a large variety of molecules. The BEB cross sections for CH and C2H2 are in good agreement with the available experimental data from ionization thresholds to hundreds of eV in incident energies.

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Shielding Strategies For Human Space Exploration Chapter 9: Hze Interactions In Biological Materials, M. Eugene Rudd Dec 1997

Shielding Strategies For Human Space Exploration Chapter 9: Hze Interactions In Biological Materials, M. Eugene Rudd

M. Eugene Rudd Publications

It is shown that most of the energy deposited by fast charged particles traversing matter occurs through ionization, i.e., the ejection of electrons during the atomic collision. The important mechanisms of ionization are identified and several methods of calculating the relevant differential and total cross sections are described. These include both classical and quantum theoretical methods and two semi-empirical models. The calculational methods were intended only for light, bare-ion projectiles, and care must be exercised in extending them to heavy, dressed projectiles.

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Joint Map Registration And High Resolution Image Estimation Using A Sequence Of Undersampled Images, Russell C. Hardie, Kenneth J. Barnard, Ernest E. Armstrong Dec 1997

Joint Map Registration And High Resolution Image Estimation Using A Sequence Of Undersampled Images, Russell C. Hardie, Kenneth J. Barnard, Ernest E. Armstrong

Electrical and Computer Engineering Faculty Publications

n many imaging systems, the detector array is not sufficiently dense to adequately sample the scene with the desired field of view. This is particularly true for many infrared focal plane arrays. Thus, the resulting images may be severely aliased. This paper examines a technique for estimating a high-resolution image, with reduced aliasing, from a sequence of undersampled frames. Several approaches to this problem have been investigated previously. However, in this paper a maximum a posteriori (MAP) framework for jointly estimating image registration parameters and the high-resolution image is presented. Several previous approaches have relied on knowing the registration parameters …

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Spin Splitting Of Donor-Bound Excitons In Zno Due To Combined Stress And Spin Exchange, D. C. Reynolds, David C. Look, B. Jogai, T. C. Collins Dec 1997

Spin Splitting Of Donor-Bound Excitons In Zno Due To Combined Stress And Spin Exchange, D. C. Reynolds, David C. Look, B. Jogai, T. C. Collins

Physics Faculty Publications

No abstract provided.

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Exotic Mesons In Quenched Lattice Qcd, James E. Hetrick, C. Bernard Dec 1997

Exotic Mesons In Quenched Lattice Qcd, James E. Hetrick, C. Bernard

All Faculty Articles - School of Engineering and Computer Science

Since gluons in QCD are interacting fundamental constituents just as quarks are, we expect that in addition to mesons made from a quark and an antiquark, there should also be glueballs and hybrids (bound states of quarks, antiquarks and gluons). In general, these states would mix strongly with the conventional q-bar-q mesons. However, they can also have exotic quantum numbers inaccessible to q-bar-q mesons. Confirmation of such states would give information on the role of "dynamical" color in low energy QCD. In the quenched approximation we present a lattice calculation of the masses of mesons with exotic quantum numbers. These …

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Bound Μ⁺Μˉ System, Ulrich D. Jentschura, Gerhard Soff, Vladimir G. Ivanov, Savely Karshenboim Dec 1997

Bound Μ⁺Μˉ System, Ulrich D. Jentschura, Gerhard Soff, Vladimir G. Ivanov, Savely Karshenboim

Physics Faculty Research & Creative Works

We consider the hyperfine structure, the atomic spectrum, and the decay channels of the bound μ+μ- system (dimuonium). The annihilation lifetimes of low-lying atomic states of the system lie in the 10-12 s range. The decay rates could be measured by detection of the decay products (high-energy photons or electron-positron pairs). The hyperfine-structure splitting of the dimuonic system and its decay rate are influenced by electronic vacuum polarization effects in the far timelike asymptotic region. This constitutes a previously unexplored kinematic regime. We evaluate next-to-leading-order radiative corrections to the decay rate of low-lying atomic states. We …

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A Search For Excited Fermions In E+P Collisions At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti Dec 1997

A Search For Excited Fermions In E+P Collisions At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

Using the ZEUS detector at HERA, we have searched for heavy excited states of electrons, neutrinos, and quarks in e+p collisions at a center-of-mass energy of 300 GeV. With an integrated luminosity of 9.4 pb-1, no evidence was found for electroweak production and decay of such states. Limits on the production cross section times branching ratio and on the characteristic couplings, f/Λ, are derived for masses up to 250 GeV. For the particular choice f/Λ = 1/Mf*, we exclude at the 95% confidence level excited electrons with mass between 30 and 200 GeV, excited electron neutrinos with mass between 40 …

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Three-Dimensional Camera Calibration Technique For Stereo Imaging Velocimetry Experiments, Mark D. Bethea, James A. Lock, Frank Merat, Paul Crouser Dec 1997

Three-Dimensional Camera Calibration Technique For Stereo Imaging Velocimetry Experiments, Mark D. Bethea, James A. Lock, Frank Merat, Paul Crouser

Physics Faculty Publications

A three-dimensional camera calibration technique is developed by combining two, 2-D camera calibrations for an orthogonal stereo viewing geometry. The left camera view (YZ view) and the right camera view (XZ view) are calibrated separately and then combined to produce an XYZ (3-D) calibration routine, Our technique employs three parallel calibration planes. One is placed along the main diagonal of the cubic experimental chamber, and the other two planes are placed known distances in front of it and behind it within the chamber. Both cameras view the calibration points on the planes simultaneously. Given the coordinates of a number of …

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Near-Field Measurements On Contrail Properties From Fuels With Different Sulfur Content, Andreas Petzold, Reinhold Busen, Franz Peter Schroder, Robert Baumann, Markus Kuhn, Johan Strom, Donald E. Hagen, Philip D. Whitefield, Darrel G. Baumgardner, Frank Arnold, Stephan Borrmann, Ulrich Schumann Dec 1997

Near-Field Measurements On Contrail Properties From Fuels With Different Sulfur Content, Andreas Petzold, Reinhold Busen, Franz Peter Schroder, Robert Baumann, Markus Kuhn, Johan Strom, Donald E. Hagen, Philip D. Whitefield, Darrel G. Baumgardner, Frank Arnold, Stephan Borrmann, Ulrich Schumann

Physics Faculty Research & Creative Works

Microphysical properties of jet exhaust aerosol and contrails were studied in the near field of the emitting aircraft for different fuel sulfur contents. Measurements were performed behind two different aircraft (ATTAS test aircraft of type VFW 614 and Airbus A310-300) using fuels with sulfur contents of 6 ppm and 2700 ppm, respectively. At closest approach (plume age < 1 s), the total number concentrations exceeded the measuring range of the condensation particle counter, i.e., N > 105 cm-3. The concentration of the dry accumulation mode aerosol, i.e., predominantly soot particles, was not affected by the fuel sulfur content. At a plume age of 10 s, an increase in total number concentration (Dp > 0.01 μm) by a …

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Unfolding Of The Period-Two Bifurcation In A Fiber Laser Pumped With Two Modulation Tones, Scott Glasgow, T. C. Newell, A. Gavrielides, V. Kovanis, D. Sukow, T. Erneux Dec 1997

Unfolding Of The Period-Two Bifurcation In A Fiber Laser Pumped With Two Modulation Tones, Scott Glasgow, T. C. Newell, A. Gavrielides, V. Kovanis, D. Sukow, T. Erneux

Faculty Publications

The effect of a small second frequency component on a pump modulated neodymium fiber laser is investigated experimentally and theoretically. This term, whose frequency is exactly half the primary driver, incites an unfolding of the attractor. It breaks the period two pitchfork bifurcation and splits the period one orbit. The modification of the bifurcation diagram is studied analytically by employing a map derived from the class B laser rate equations. We determine specific conditions and scaling laws for this phenomenon. Our analytical predictions are in good agreement with recorded experimental data.

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A New Dynamic Mechanism Of Topological Charge Creation In A Commensurate One-Dimensional Charge Density Wave Near The Contact With A Normal Metal, A. S. Rozhavsky, Yuriy V. Pershin Dr, A. S. Kovalev Dec 1997

A New Dynamic Mechanism Of Topological Charge Creation In A Commensurate One-Dimensional Charge Density Wave Near The Contact With A Normal Metal, A. S. Rozhavsky, Yuriy V. Pershin Dr, A. S. Kovalev

Faculty Publications

The dynamics of conversion of conduction electrons into topological solitons of a charge density wave (CDW) commensurability in an external electric field is investigated. A novel mechanism of initiation of a nonlinear CDW current in the vicinity of the interface between a CDW and a normal metal is revealed and explained. The nonlinear current is produced by the conduction solitons created by the moving profile of the order parameter, formed during the conversion of electrons into collective phase excitations of a CDW. The field dependence of the current is of threshold nature and has no analogs in the bulk mechanisms …

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Observation Of Scaling Violations In Scaled Momentum Distributions At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti Nov 1997

Observation Of Scaling Violations In Scaled Momentum Distributions At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of x and Q2 using the ZEUS detector. The evolution of the scaled momentum, xp, with Q2, in the range 10 to 1280 GeV2, has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a single experiment, for scaling violations in scaled momenta as a function of Q2. © 1997 Elsevier Science B.V.

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Low-Field Hole Mobility In A Photorefractive Polymer, Arosha Goonesekera, Stephen Ducharme, James M. Takacs, Lei Zhang Nov 1997

Low-Field Hole Mobility In A Photorefractive Polymer, Arosha Goonesekera, Stephen Ducharme, James M. Takacs, Lei Zhang

Stephen Ducharme Publications

We present the time-of-flight measurements of hole mobility in a photorefractive polymer composite as a function of temperature and applied electric field. The analysis shows that the temperature dependence of the low-field mobility is in apparent disagreement with the predictions of the Gaussian disorder model and also with polaron models.

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Study Of The Decay Τ-→2Π-Π+3Π0ΝΤ, S. Anderson, Kenneth A. Bloom, Cleo Collaboration Nov 1997

Study Of The Decay Τ-→2Π-Π+3Π0ΝΤ, S. Anderson, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

The decay τ-→2π-π+3π0ντ has been studied with the CLEO II detector at the Cornell Electron Storage Ring. The branching fraction is measured to be (2.85 ± 0.56 ± 0.51) X 10-4. The result is in good agreement with the isospin expectation but somewhat below the conserved-vectorcurrent prediction. We have searched for resonance substructure in the decay. Within the statistical precision, the decay is saturated by the channels τ-→π-2π0ωντ, 2π-π+ωντ, and π-2π0ων …

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Limit On The Two-Photon Production Of The Glueball Candidate FJ(2220) At The Cornell Electron Storage Ring, R. Godang, Kenneth A. Bloom, Cleo Collaboration Nov 1997

Limit On The Two-Photon Production Of The Glueball Candidate FJ(2220) At The Cornell Electron Storage Ring, R. Godang, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

We use the CLEO detector at the Cornell e+e- storage ring, CESR, to search for the two-photon production of the glueball candidate fJ (2220) in its decay to KsKs. We present a restrictive upper limit on the product of the two-photon partial width and the KsKs branching fraction, (Γγγ BKsKs)fJ(2220). We use this limit to calculate a lower limit on the stickiness, which is a measure of the two-gluon coupling relative to the two-photon coupling. This limit on stickiness …

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Upper Limits To The Outflow Of Ions At Mars: Implications For Atmospheric Evolution, Jane L. Fox Nov 1997

Upper Limits To The Outflow Of Ions At Mars: Implications For Atmospheric Evolution, Jane L. Fox

Physics Faculty Publications

Escape of ions is potentially important for the evolution of volatiles on Mars, but the mechanisms and rates of ion escape processes are not fully understood. Instruments on the Russian Phobos 2 orbiter have, however, measured fluxes of heavy ions apparently of ionospheric origin in the optical shadow of Mars. These ions are assumed to arise from escape processes induced by the interaction of the solar wind with the ionosphere. We determine here upper limits to the ion loss rates by imposing upward flux boundary conditions on models of the low and high solar activity Mars ionosphere. The maximum fluxes …

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Characterizing The Coherence Of Bose-Einstein Condensates And Atom Lasers, R. J. Dodd, Charles W. Clark, Mark Edwards, Keith Burnett Nov 1997

Characterizing The Coherence Of Bose-Einstein Condensates And Atom Lasers, R. J. Dodd, Charles W. Clark, Mark Edwards, Keith Burnett

Department of Physics and Astronomy Faculty Publications

For a dilute, interacting Bose gas of magnetically-trapped atoms at temperatures below the critical temperature T 0 for Bose-Einstein condensation, we determine the second-order coherence function g (2)(r 1, r 2) within the framework of a finite-temperature quantum field theory. We show that, because of the different spatial distributions of condensate and thermal atoms in the trap, g (2)(r 1, r 2) does not depend on |r 1 - r 2| alone. This means that the experimental determinations of g (2) reported to date give only its spatial average. Such an average may underestimate the degree of coherence attainable in …

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Observation Of Isolated High-ET Photons In Photoproduction At Hera: Zeus Collaboration, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti Nov 1997

Observation Of Isolated High-ET Photons In Photoproduction At Hera: Zeus Collaboration, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

Events containing an isolated prompt photon with high transverse energy, together with a balancing jet, have been observed for the first time in photoproduction at HERA. The data were taken with the ZEUS detector, in a γp centre of mass energy range 120-250 GeV. The fraction of the incoming photon energy participating in the production of the prompt photon and the jet, xγ, shows a strong peak near unity, consistent with LO QCD Monte Carlo predictions. In the transverse energy and pseudorapidity range 5 ≤ EγT < 10 GeV, -0.7 ≤ ηγ < 0.8, EjetT ≥ 5 GeV, and -1.5 ≤ ηjet ≤ 1.8, with xOBSγ > 0.8, the measured cross section is 15.3 ± 3.8 ± 1.8 pb, in good …

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Hands-On Phasors And Multiple-Slit Interference, Rand S. Worland, Matthew J. Moelter Nov 1997

Hands-On Phasors And Multiple-Slit Interference, Rand S. Worland, Matthew J. Moelter

Physics

No abstract provided.

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Teaching College Physics To A Blind Student, Michelle Parry, Mark Brazier, Ephraim Fischbach Nov 1997

Teaching College Physics To A Blind Student, Michelle Parry, Mark Brazier, Ephraim Fischbach

Chemistry & Physics Faculty Publications

No abstract provided.

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Spectrum Of Hot O At The Exobases Of The Terrestrial Planets, Jane L. Fox, Aleksander B. Hać Nov 1997

Spectrum Of Hot O At The Exobases Of The Terrestrial Planets, Jane L. Fox, Aleksander B. Hać

Physics Faculty Publications

The distribution of energetic O produced in dissociative recombination of O2+ at the exobases of the terrestrial planets is important in determining the structure of the outer hot O coronas and for the escape flux of O from Mars. Using recently measured values for the branching ratios of the energetically allowed channels in O2+ dissociative recombination, along with models of the vibrational distribution of O2+, we compute the velocity distribution of hot O atoms produced at the exobases of Mars, Venus, and Earth. We take into account the effects of the ion and …

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