Astrophysics and Astronomy Commons^™

Navigating The Starless Night: Strategies For Understanding Autobiogeography, Matthew Wolf-Meyer, Davin Heckman

Reconstruction: Studies in Contemporary Culture

[First paragraph]

Ancient mapmakers relied upon the presence of celestial bodies for their conceptualization of the world, for their external knowledge-making tools, as if a far-off body could help to make sense of our terrestrial life/as if it couldn't. Cosmology, as a practice, relied on the construction of an external body of knowledge that the local meaning-maker could situate him- or herself into, and more broadly, their entire society and culture -- the interior is determined by its relationship to the exterior (or the exteriorized). For the ancient Greeks then, the font of Western culture, this cosmology works at once …

Negative-Parity Baryon Masses Using An O(A)-Improved Fermion Action, M. Göckeler, R. Horsley, D. Pleiter, P. E. L. Rakow, G. Schierholz, C. M. Maynard, D. G. Richards

Physics Faculty Publications

We present a calculation of the mass of the lowest-lying negative-parity J=1/2− state in quenched QCD. Results are obtained using a non-perturbatively O(a)-improved clover fermion action, and a splitting is found between the mass of the nucleon, and its parity partner. The calculation is performed on two lattice volumes and at three lattice spacings, enabling a study of both finite-volume and finite lattice-spacing uncertainties. A comparison is made with results obtained using the unimproved Wilson fermion action.

Exclusive Electroproduction Of ᵠ Mesons At 4.2 Gev, M. Bektasoglu, L. Ciciani, G. E. Dodge, T. A. Forest, C. E. Hyde-Wright, S. E. Kuhn, L. M. Qin, F. Sabatié, L. B. Weinstein, Et Al., The Clas Collaboration

Physics Faculty Publications

We studied the exclusive reaction ep → e' p' ᵠ using the ᵠ →K⁺K^- decay mode. The data were collected using a 4.2 GeV incident electron beam and the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. Our experiment covers the range in Q² from 0.7 to 2.2 GeV²and W from 2.0 to 2.6 GeV. Taken together with all previous data, we find a consistent picture of ᵠ production on the proton. Our measurement shows the expected decrease of the t slope with the vector-meson formation time c Δ t …

Mathematical Models Of Quiescent Solar Prominences, Iain Mckaig

Mathematics & Statistics Theses & Dissertations

Magnetic fields in the solar atmosphere suspend and insulate dense regions of cool plasma known as prominences. The convection zone may be the mechanism that both generates and expels this magnetic flux through the photosphere in order to make these formations possible. The connection is examined here by modeling the convection zone as both one-dimensional, then more realistically, two-dimensional.

First a Dirichlet problem on a semi-infinite strip is solved using conformal mapping and the method of images. The base of the strip represents the photosphere where a current distribution can be given as a boundary condition, and the strip extends …

Effective Field Theory For The Small-X Evolution, I. Balitsky

Physics Faculty Publications

The small-x behavior of structure functions in the saturation region is determined by the non-linear generalization of the BFKL equation. I suggest the effective field theory for the small-x evolution which solves formally this equation. The result is the 2+1 functional integral for the structure functions at small x.

Corrected Article: Exclusive Electroproduction Of ᵠ Mesons At 4.2 Gev [Physical. Rev. C 63, 065205, (2001)], M. Bektasoglu, L. Ciciani, G. E. Dodge, T. A. Forest, C. E. Hyde-Wright, S. E. Kuhn, L. M. Qin, F. Sabatié, L. B. Weinstein, Et Al., The Clas Collaboration

Physics Faculty Publications

We studied the exclusive reaction ep → e' p' ᵠ using the ᵠ →K⁺K^- decay mode. The data were collected using a 4.2 GeV incident electron beam and the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. Our experiment covers the range in Q² from 0.7 to 2.2 GeV²and W from 2.0 to 2.6 GeV. Taken together with all previous data, we find a consistent picture of ᵠ production on the proton. Our measurement shows the expected decrease of the t slope with the vector-meson formation time c Δ t …

A Solar Comparison, Larry Weinstein

Physics Faculty Publications

[First paragraph] Gilbert Ward [Phys.Teach 38, 333 (Sept. 2000)] states, "You emit more than 7000 times as much heat per unit mass as the Sun does." This difference was pointed out to me much more graphically by Brian Quinn many years ago as, "If the sun were made out of gerbils, the Earth would be incinerated."

Scattering From Stellar Acoustic-Gravity Potentials: Ii. Phase Shifts Via The First Born Approximation, J. A. Adam, I. Mckaig

Mathematics & Statistics Faculty Publications

Using the first Born approximation, properties of the scattering phase shift are investigated for waves that are scattered by a schematic representation of a large-scale “stellar potential,” i.e., one for which the star itself is viewed as the potential inducing a phase shift in an incoming wave. In particular, the phase shift properties are examined as functions of the relative wavenumber (α) and the azimuthal wavenumber (l), high l-values being of interest in helioseismology.

Evidence For Virtual Compton Scattering From Proton, J.F.J. Van Den Brand, R. Ent, P. L. Anthony, R. G. Arnold, J. Arrington, E. J. Beise, J. E. Belz, P. E. Bosted, H. J. Bulten, M. S. Chapman, K. P. Coulter, F. S. Dietrich, M. Epstein, B. W. Filippone, H. Gao, R. A. Gearhart, D. F. Geesaman, J.-O. Hansen, R. J. Holt, H. E. Jackson, C. E. Jones, C. E. Keppel, E. R. Kinney, S. Kuhn, K. Lee, W. Lorenzon, A. Lung, N.C.R. Makins, D.J. Margaziotis, R.D. Mckeown, R.G. Milner, B. Mueller, J. Napolitano, J. Nelson, T. G. O'Neill, V. Pavavassiliou, G. G. Petratos, D. H. Potterveld, S. E. Rock, M. Spengos, Z. M. Szalata, L. H. Tao, K Van Bibber, D. A. Wasson, J.L. White, B. Zeidman

Physics Faculty Publications

In virtual Compton scattering an electron is scattered off a nucleon such that the nucleon emits a photon. We show that these events can be selected experimentally, and present the first evidence for virtual Compton scattering from the proton in data obtained at the Stanford Linear Accelerator Center. The angular and energy dependence of the data is well described by a calculation that includes the coherent sum of electron and proton radiation.

Exclusive Electron Scattering From Deuterium At High Momentum Transfer, H. J. Bulten, P. L. Anthony, R. G. Arnold, J. Arrington, E. J. Beise, E. Belz, K. Van Bibber, P. E. Bosted, J.F.J. Van Den Brand, M. S. Chapman, K. P. Coulter, F. S. Dietrich, R. Ent, M. Epstein, B. W. Filippone, H. Gao, R.A. Gearhart, D. F. Geesaman, J.-O. Hansen, R. J. Holt, H. E. Jackson, C. E. Jones, C. E. Keppel, E. Kinney, S. E. Kuhn, K. Lee, W. Lorenzon, A. Lung, N.C.R. Makins, D. J. Margaziotis, R.D. Mckeown, R. G. Milner, B. Mueller, J. Napolitano, J. Nelson, T.G. O'Neill, V. Papavassiliou, G. G. Petratos, D. H. Potterveld, S. E. Rock, M. Spengos, Z. M. Szalata, L. H. Tao, J. L. White, B. Zeidman

Physics Faculty Publications

Cross sections are presented for the reaction ²H(e,e′p)n for momentum transfers in the range 1.2 ≤Q²≤ 6.8 (GeV/c)2 and for missing momenta from 0 to 250 MeV/c. The longitudinal-transverse interference structure function has been separated at Q²=1.2(GeV/c)². The observables are compared to calculations performed in nonrelativistic and relativistic frameworks. The data are best described by a fully relativistic calculation.

Precision Measurement Of Relative Dipole Matrix Elements In Atomic Sodium, Rodney P. Meyer

Physics Theses & Dissertations

Relative dipole matrix elements are measured by means of a new spectroscopic technique called polarization interference spectroscopy. It is a two-color two-photon nonresonant process that maps the matrix elements into the energy domain by means of quantum mechanical interference. The technique measures the relative magnitude of the reduced matrix elements, particularly those involving excited states, to accuracies that are an order of magnitude better than previously available. Also, for the first time the relative phase of the reduced matrix elements is measured. The ratio of reduced matrix elements for the transitions 3s ²S_1/2 →3P ²P_3/2 →5s …

Strong Magnetic Field Effects And Molecular Processes With Applications To White Dwarfs, Phillip C. Stancil

Physics Theses & Dissertations

Radiative transitions of hydrogenlike atoms in external magnetic fields of strength applicable to magnetic white dwarfs, i.e. B < 10³ megagauss, have been investigated for field-free principal quantum numbers n < 6. Finite proton mass corrections are included. Relativistic corrections are also investigated. Transition probabilities are determined using the length, velocity, and acceleration forms of the electric dipole operator. Discrepancies between previous calculations and magnetic white dwarf observations of low-lying boundbound transitions have been studied. New results for high-lying transitions are also obtained.

The transition probability for the hydrogenlike 2s two-photon decay has been investigated and shown to increase substantially with field strength. The computed two-photon spectra show resonances and interference minima. Anomalous Zeeman depolarization features are found in computed two-photon polarization spectra of alkali atoms in laboratory strength magnetic fields. A previously observed fine structure depolarization feature is shown to decay with decreasing field strength.

Nuclear Fragmentation Energy And Momentum Transfer Distributions In Relativistic Heavy-Ion Collisions, Ferdous Khan

Physics Theses & Dissertations

An optical model description of energy and momentum transfer in relativistic heavy-ion collisions, based upon composite particle multiple scattering theory, is presented. Transverse and longitudinal momentum transfers to the projectile are shown to arise from the real and absorptive part of the optical potential, respectively. Comparisons of fragment momentum distribution observables with experiments are made and trends outlined based on our knowledge of the underlying nucleon-nucleon interaction. Corrections to the above calculations are discussed. Finally, use of the model as a tool for estimating collision impact parameters is indicated.

The Energy-Dependence Of Polarization Observables In The ²H(D,Γ)⁴He Reaction, H. R. Weller, R. M. Whitton, J. Langenbrunner, Evans Hayward, W. R. Dodge, S. Kuhn, D. R. Tilley

Physics Faculty Publications

Measurements of the tensor and vector analyzing powers, A_yy(130°) and A_y(130°), have been obtained for the ²H(d,γ )⁴He reaction for energies ranging from E_d(lab) = 0.3 MeV to E_d(lab) = _{50 MeV}. The A_yy(130°) data are sensitive to the D-state present in the ground state of ⁴He and are observed to have their maximum value near E_d = 30 MeV. The vector analyzing power data show a maximum near E_d = 3 MeV. The data are compared to the results of a microscopic …

Influence Of Nonequilibrium Radiation And Shape Change On The Flowfield Of A Jupiter Probe With Ablation And Mass Injection, Sundaresa Venkata Subramanian

Mechanical & Aerospace Engineering Theses & Dissertations

The influence of nonequilibrium radiative energy transfer and the effect of probe configuration changes on the flow phenomena around a Jovian entry body is investigated. The radiating shock-layer flow is assumed to be axisymmetric, viscous, laminar and in chemical equilibrium. The radiative transfer equations are derived under nonequilibrium conditions which include multi-level energy transitions. The equilibrium radiative transfer is calculated with an existing nongray radiation model which accounts for molecular band, atomic line and continuum transitions. The nonequilibrium results are obtained with and without ablation injection in the shock layer. The nonequilibrium results are found to be influenced greatly by …

Solar Magnetoatmospheric Waves-A Simplified Mathematical Treatment, John A. Adam

Mathematics & Statistics Faculty Publications

The inhomogeneous wave equation for a special class of magnetoatmospheric waves is formally solved, and the principle of stationary phase used to provide information on the group velocity properties of such waves. General results are presented concerning the associated mechanical energy flux. The basic problem considered is relevant to waves initiated by sudden events in the solar atmosphere.

Sensitivity Of A Gas Filter Correlation Instrument To Variations In Atmospheric Profile And Earth Surface Temperatures, Joseph C. Casas

Physics Theses & Dissertations

The Gas Filter Correlation Radiometer Analyzer (GFCR), in application to the remote sensing of trace gases in the atmosphere, is potentially limited by the sensitivity of the measured upwelling thermal radiation to surface temperature and atmospheric temperature conditions. This study has been carried out to examine the principles of operation of the GFCR Analyzer and to obtain quantitative estimates of the errors produced in GFCR Analyzer measurements of CO (4.6μ), S02 (8.6μ), NH3 (11.0μ), and CH4 (8.1μ) resulting from uncertainties in the atmospheric temperature profile and ground temperature.

A simple mathematical prototype GFCR Analyzer was assumed. A line-by-line atmospheric radiative …