Latest content added for Digital Libraryhttps://digital.library.unt.edu/search/?amp=&t5=dc_subject&q5=%22Amplitudes%22&searchType=advanced&fq=untl_institution%3AUNTGD2019-01-23T12:54:46-06:00UNT LibrariesThis is a custom feed for searching Digital LibraryFar Scrape-Off Layer and Near Wall Plasma Studies in DIII-D2019-01-23T12:54:46-06:00https://digital.library.unt.edu/ark:/67531/metadc1406623/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc1406623/"><img alt="Far Scrape-Off Layer and Near Wall Plasma Studies in DIII-D" title="Far Scrape-Off Layer and Near Wall Plasma Studies in DIII-D" src="https://digital.library.unt.edu/ark:/67531/metadc1406623/small/"/></a></p><p>Far scrape-off layer (SOL) plasma parameters in DIII-D depend strongly on the discharge density and confinement regime. In L-mode, cross-field transport increases with the average discharge density and elevates the far SOL density, thus increasing plasma-wall contact. Far SOL density near the low field side (LFS) of the main chamber wall also increases with decreasing plasma current and with decreasing outer wall gap. In H-mode, between edge localized modes (ELMs), plasma-wall contact is weaker than in L-mode. During ELMs plasma fluxes to the LFS wall increase to, or above the L-mode levels. A large fraction of the net cross-field fluxes is convected through the SOL by large amplitude intermittent transport events. In high density L-mode and during ELMs in H-mode, intermittent events propagate all the way to the LFS wall and may cause sputtering.</p>Picosecond resolution soft x-ray laser plasma interferometry2019-01-23T12:54:46-06:00https://digital.library.unt.edu/ark:/67531/metadc1405840/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc1405840/"><img alt="Picosecond resolution soft x-ray laser plasma interferometry" title="Picosecond resolution soft x-ray laser plasma interferometry" src="https://digital.library.unt.edu/ark:/67531/metadc1405840/small/"/></a></p><p>We describe a soft x-ray laser interferometry technique that allows two-dimensional diagnosis of plasma electron density with picosecond time resolution. It consists of the combination of a robust high throughput amplitude division interferometer and a 14.7 nm transient inversion soft x-ray laser that produces {approx} 5 ps pulses. Due to its picosecond resolution and short wavelength scalability, this technique has potential for extending the high inherent precision of soft x-ray laser interferometry to the study of very dense plasmas of significant fundamental and practical interest, such as those investigated for inertial confined fusion. Results of its use in the diagnostics of dense large scale laser-created plasmas are presented.</p>The BNL Super Neutrino Beam Project2019-01-23T12:54:46-06:00https://digital.library.unt.edu/ark:/67531/metadc1409565/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc1409565/"><img alt="The BNL Super Neutrino Beam Project" title="The BNL Super Neutrino Beam Project" src="https://digital.library.unt.edu/ark:/67531/metadc1409565/small/"/></a></p><p>To determine the neutrino mixing amplitudes and phase accurately, as well as the CP violation parameters, a very long base line super neutrino beam facility is needed. This is possible due to the long distance and wideband nature of the neutrino beam for the observation of several oscillations from one species of the neutrino to the other [1,2]. BNL plans to upgrade the AGS proton beam from the current 0.14 MW to higher than 1.0 MW and beyond for such a neutrino facility which consists of three major subsystems. First is a 1.5 GeV superconducting linac to replace the booster as injector for the AGS, second is the performance upgrade for the AGS itself for the higher intensity and repetition rate, and finally is target and horn system for the neutrino production. The major contribution for the higher power is from the increase of the repetition rate of the AGS form 0.3 Hz to 2.5 Hz, with moderate increase from the intensity [3]. The design consideration to achieve high intensity and low losses for the linac and the AGS will be reviewed. The target horn design for high power operation and easy maintenance will also be presented.</p>Consistency between Angular Distributions and Integral Quantities Calculated with the Nuclear Ramsauer Model2019-01-23T12:54:46-06:00https://digital.library.unt.edu/ark:/67531/metadc1410454/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc1410454/"><img alt="Consistency between Angular Distributions and Integral Quantities Calculated with the Nuclear Ramsauer Model" title="Consistency between Angular Distributions and Integral Quantities Calculated with the Nuclear Ramsauer Model" src="https://digital.library.unt.edu/ark:/67531/metadc1410454/small/"/></a></p><p>This report reviews the connection between the exact expression for the scattering amplitude and its approximation by the nuclear Ramsauer model. This approximation is well defined only for integral values of kR, the product of the neutron wave number and a nuclear radius parameter. Using the model between these integral values requires the introduction of an interpolation scheme. We show the effects on physical observables of adding an extra term to the scattering amplitude. By choosing the functional form of this term it is possible to obtain smooth behavior with energy of some of the physical observables, but not all.</p>Measurement of the angular distribution in anti-p p ---> psi(2S) ---> e+ e-2019-01-23T12:54:46-06:00https://digital.library.unt.edu/ark:/67531/metadc1406092/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc1406092/"><img alt="Measurement of the angular distribution in anti-p p ---> psi(2S) ---> e+ e-" title="Measurement of the angular distribution in anti-p p ---> psi(2S) ---> e+ e-" src="https://digital.library.unt.edu/ark:/67531/metadc1406092/small/"/></a></p><p>The authors present the first measurement of the angular distribution for the exclusive process {bar p}p {yields} {psi}(2S) {yields} e{sup +}e{sup -} based on a sample of 6844 events collected by the Fermilab E835 experiment. They find that the angular distribution is well described by the expected functional form dN/d cos {theta}* {proportional_to} 1 + {lambda} cos{sup 2} {theta}*, where {theta}* is the angle between the antiproton and the electron in the center of mass frame, with {lambda} = 0.67 {+-} 0.15(stat.) {+-} 0.04(sys.). The measured value for {lambda} implies a small but non zero {psi}(2S) helicity 0 formation amplitude in {bar p}p, comparable to what is observed in J/{psi} decays to baryon pairs.</p>The MACHO Project Large Magellanic Cloud Variable Star Inventory. XIII. Fourier Parameters for the First Overtone RR Lyrae Variables and the LMC Distance2019-01-23T12:54:46-06:00https://digital.library.unt.edu/ark:/67531/metadc1416294/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc1416294/"><img alt="The MACHO Project Large Magellanic Cloud Variable Star Inventory. XIII. Fourier Parameters for the First Overtone RR Lyrae Variables and the LMC Distance" title="The MACHO Project Large Magellanic Cloud Variable Star Inventory. XIII. Fourier Parameters for the First Overtone RR Lyrae Variables and the LMC Distance" src="https://digital.library.unt.edu/ark:/67531/metadc1416294/small/"/></a></p><p>Shapes of RR Lyrae light curves can be described in terms of Fourier coefficients which past research has linked with physical characteristics such as luminosity, mass and temperature. Fourier coefficients have been derived for the V and R light curves of 785 overtone RR Lyrae variables in 16 MACHO fields near the bar of the LMC. In general, the Fourier phase differences {phi}{sub 21}, {phi}{sub 31} and {phi}{sub 41} increase and the amplitude ratio R{sub 21} decreases with increasing period. The coefficients for both the V and R magnitudes follow these patterns, but the phase differences for the R curves are on average slightly greater, and their amplitudes are about 20% smaller, than the ones for the V curves. The {phi}{sub 31} and R{sub 21} coefficients have been compared with those of the first overtone RR Lyrae variables in the Galactic globular clusters NGC 6441, M107, M5, M3, M2, {omega} Centauri and M68. The results indicate that many of the LMC variables have properties similar to the ones in M2, M3, M5 and the Oosterhoff type I variables in {omega} Cen, but they are different from the Oosterhoff type II variables in {omega} Cen. Equations derived from hydrodynamic pulsation models have been used to calculate the luminosity and temperature for the 330 bona fide first-overtone variables. The results indicate that they have Log L in the range 1.6 to 1.8 L{sub {center_dot}} and log T{sub eff} between 3.85 and 3.87. Based on these temperatures, a mean color excess E(V-R) = 0.08 mag, equivalent to E(B-V) = 0.14 mag, has been estimated for these 330 stars. The 80 M5-like variables (selected according to their location in the {phi}{sub 31} - log P plot) are used to determine an LMC distance. After correcting for the effects of extinction and crowding, a mean apparent magnitude < V{sub 0} > = 18.99 {+-} 0.02 (statistical) {+-} 0.16 (systematic) has been estimated for these 80 stars. Combining this with a mean absolute magnitude M{sub V} = 0.56 {+-} 0.06 for M5-like stars derived from Baade-Wesselink analyses, main sequence fitting, Fourier parameters and the trigonometric parallax of RR Lyrae, they derive an LMC distance modulus {mu} = 18.43 {+-} 0.06 (statistical) {+-} (systematic) mag. The large systematic error arises from the difficulties of correcting for interstellar extinction and for crowding.</p>A Revised Magnitude and Distance Amplitude Correction (MDAC2) Procedure for Regional Seismic Discriminants: Theory and Testing at NTS2019-01-23T12:54:46-06:00https://digital.library.unt.edu/ark:/67531/metadc1411205/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc1411205/"><img alt="A Revised Magnitude and Distance Amplitude Correction (MDAC2) Procedure for Regional Seismic Discriminants: Theory and Testing at NTS" title="A Revised Magnitude and Distance Amplitude Correction (MDAC2) Procedure for Regional Seismic Discriminants: Theory and Testing at NTS" src="https://digital.library.unt.edu/ark:/67531/metadc1411205/small/"/></a></p><p>The Magnitude and Distance Amplitude Correction (MDAC; Taylor and Hartse, 1998; Taylor et al., 2002) procedure for correcting regional seismic amplitudes for seismic event identification has been modified to include more realistic earthquake source models and source scaling. In the MDAC2 formulation we generalize the Brune (1970) earthquake source spectrum to use a more physical apparent stress model that can represent non-constant stress-drop scaling. We also event include a parameter that allows for variable P-wave and S-wave comer frequency scaling, imposing some of the constraints of ratio correction techniques (Rodger and Walter, 2002). Very Stable moment magnitude measures (Mayeda et al., 2002) from regional coda wave envelopes that have been tied to independently derived regional seismic moments are incorporated. This eliminates two fitting parameters that were necessary in relating seismic moment to magnitude. The incorporation of Bayesian tomography to replace the assumption of a constant Q0 model is also described. These modifications allow for more flexibility in the MDAC grid-search procedure. The direct tie to regional seismic moment rather than body wave magnitude reduces effects of upper mantle bias on the corrected amplitudes. In this paper, we develop the theory and test the formulation on Nevada Test Site (NTS) data.</p>Techniques in meson spectroscopy2019-01-12T16:41:59-06:00https://digital.library.unt.edu/ark:/67531/metadc1395028/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc1395028/"><img alt="Techniques in meson spectroscopy" title="Techniques in meson spectroscopy" src="https://digital.library.unt.edu/ark:/67531/metadc1395028/small/"/></a></p><p>This report contains lectures on the following topics: the quark model and beyond using quantum chromodynamics; analysis of formation reactions; energy dependence of the partial wave amplitudes; where the data for the t-matrix analysis comes from; and coupled channel analysis of isoscalar mesons.</p>Hadron dynamics in high-energy pion-nucleus scattering2018-11-03T11:47:27-05:00https://digital.library.unt.edu/ark:/67531/metadc1311452/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc1311452/"><img alt="Hadron dynamics in high-energy pion-nucleus scattering" title="Hadron dynamics in high-energy pion-nucleus scattering" src="https://digital.library.unt.edu/ark:/67531/metadc1311452/small/"/></a></p><p>It is argued that pion-nucleus scattering at high energy (above 300 MeV) is likely to be easier to interpret than it has been at lower energies where the {Delta}{sub 33} resonance dominates. We establish this by examining the relative importance of various dynamic ingredients of scattering theory for high-energy pions and comparing different versions of the theory: a ``model-exact`` microscopic optical model and an eikonal approximation. For nuclei as heavy as Ca, the eikonal theory is an excellent approximation to the full theory for the angular distribution out to the position of the second minimum in the cross section. The prospects for using high-energy pions to examine modifications of nucleons and baryon resonances in nuclei, nuclear structure, exchange currents, short-range correlations, and to characterize pion propagation are discussed.</p>Ringwaldmania reconsidered2018-10-12T06:44:00-05:00https://digital.library.unt.edu/ark:/67531/metadc1272158/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc1272158/"><img alt="Ringwaldmania reconsidered" title="Ringwaldmania reconsidered" src="https://digital.library.unt.edu/ark:/67531/metadc1272158/small/"/></a></p><p>The exciting possibility that anomalous baryon and lepton number violation might be observable at the next generation of supercolliders is suggested by an instanton calculation due to Ringwald and Espinoa. Here, the current controversial status of these claims is discussed, and progress on several fronts is described.</p>