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Far Scrape-Off Layer and Near Wall Plasma Studies in DIII-D

Description: 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.
Date: December 3, 2004
Creator: Rudakov, D; Boedo, J; Moyer, R; Brooks, N; Doerner, R; Evans, T et al.
Partner: UNT Libraries Government Documents Department

Picosecond resolution soft x-ray laser plasma interferometry

Description: 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.
Date: December 1, 2003
Creator: Moon, S; Nilsen, J; Ng, A; Shlyaptsev, V; Dunn, J; Hunter, J et al.
Partner: UNT Libraries Government Documents Department

The BNL Super Neutrino Beam Project

Description: 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.
Date: December 2, 2004
Creator: Weng, W-T. & Raparia, D.
Partner: UNT Libraries Government Documents Department

Consistency between Angular Distributions and Integral Quantities Calculated with the Nuclear Ramsauer Model

Description: 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.
Date: December 20, 2004
Creator: Dietrich, F S
Partner: UNT Libraries Government Documents Department

Measurement of the angular distribution in anti-p p ---> psi(2S) ---> e+ e-

Description: 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.
Date: December 1, 2004
Creator: Ambrogiani, M.; Andreotti, M.; Argiro, S.; Bagnasco, S.; Baldini, W.; Bettoni, D. et al.
Partner: UNT Libraries Government Documents Department

The MACHO Project Large Magellanic Cloud Variable Star Inventory. XIII. Fourier Parameters for the First Overtone RR Lyrae Variables and the LMC Distance

Description: 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 ...
Date: December 31, 2003
Creator: Alcock, C; Alves, D; Axelrod, T; Becker, A; Bennett, D; Clement, C et al.
Partner: UNT Libraries Government Documents Department

A Revised Magnitude and Distance Amplitude Correction (MDAC2) Procedure for Regional Seismic Discriminants: Theory and Testing at NTS

Description: 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.
Date: December 21, 2001
Creator: Walter, W R & Taylor, S R
Partner: UNT Libraries Government Documents Department

Techniques in meson spectroscopy

Description: 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.
Date: December 31, 1991
Creator: Longacre, R. S.
Partner: UNT Libraries Government Documents Department

Hadron dynamics in high-energy pion-nucleus scattering

Description: 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.
Date: December 31, 1992
Creator: Johnson, M. B.
Partner: UNT Libraries Government Documents Department

Ringwaldmania reconsidered

Description: 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.
Date: December 31, 1991
Creator: Mattis, M. P.
Partner: UNT Libraries Government Documents Department

Narrow structure in {Lambda}d scattering near the {Sigma} threshold ({sub {Sigma}}{sup 3}He states)

Description: A separable-potential, Faddeev-type calculation of {Lambda}-deuteron scattering near the threshold for {Sigma} production is shown to produce structure (a resonance peak) in the cross section which lies below the {Sigma} threshold for two different YN ({Lambda}N-{Sigma}N coupled-channel) potential models. In one case the {Sigma}NN eigenvalue corresponds to a pole which lies below threshold (bound) and in the second case the poles lies above the threshold.
Date: December 31, 1991
Creator: Gibson, B. F. & Afnan, I. R.
Partner: UNT Libraries Government Documents Department

The E2/M1 mixing ratio in the excitation of the {Delta} from polarized photo-reactions

Description: In constituent quark models, a tensor interaction, mixing quark spins with their relative motion, is introduced to reproduce the observed baryon spectrum. This has a consequence completely analogous to the nuclear tensor force between the n and p in deuterium. A D state component is mixed into what would otherwise be a purely S-wave object. The D-wave component breaks spherical symmetry, resulting in a non-vanishing matrix element for the nucleon and a static quadrupole moment and deformation for its first excited state, the {Delta} resonance, at {approximately}325 MeV. The magnitude and sign of this D-state component are quite sensitive to the internal structure of the proton and have been of great interest in recent years. The intrinsic deformation of the spin 1/2 nucleon cannot be observed directly; it must be inferred from transition amplitudes such as N {yields} {Delta}. In a spherical bag model, the {Delta} is viewed as a pure quark-spin-flip transition proceeding only through M1 excitation. If there are D-state admixtures in the ground state of the nucleon and/or {Delta}, quadrupole excitation, in addition to spin-flip M1, is also allowed. The problem is to evaluate the relative magnitude of this E2 excitation in the presence of the dominant M1 transition. A variety of models predict this mixing ratio to be quite small, anywhere from {minus}0.9% to {minus}6%, so that a high degree of precision is demanded of experiment.
Date: December 1, 1993
Creator: Collaboration, The LEGS
Partner: UNT Libraries Government Documents Department

Resonant and non-resonant magnetic scattering

Description: The tunability and the polarization of synchrotron radiation open upon new possibilities for the study of magnetism. Studies on magnetic materials performed at the National Synchrotron Light Source are reviewed, and thy fall into four areas: structure, evolution of magnetic order, separation of L and S, and resonance effects. In the vicinity of atomic absorption edges, the Faraday effect, magnetic circular dichroism, and resonant magnetic scattering are all related resonance effects which measure the spin polarized density of states. The production and analysis of polarized beams are discussed in the context of the study of magnetism with synchrotron radiation.
Date: December 31, 1991
Creator: McWhan, D. B.; Hastings, J. B.; Kao, C. C. & Siddons, D. P.
Partner: UNT Libraries Government Documents Department

Inelastic electron scattering from surfaces. Progress report for second grant year

Description: This report contains highlights of accomplishments of the past year, for the University of California, Irvine and the University of Wisconsin, Milwaukee collaboration on surface excitations, and their interactions with low energy electrons. In addition, we present a summary of future research to be carried out in the coming grant year.
Date: December 31, 1991
Creator: Tong, S. Y. & Mills, D. L.
Partner: UNT Libraries Government Documents Department

Proton-proton and proton-antiproton elastic scattering at high energies: Theory, phenomenology, and experiment

Description: This is a brief review of the progress in the understanding, during the past twenty years, of hadronic elastic scattering near the forward direction at high energies. On the basis of quantum gauge field theories, the Pomeron is found to be a branch cut above 1. Using the physical picture that this result implies, phenomenology for proton-proton and antiproton-proton elastic scattering is constructed. Two noteworthy features are that, at high energies, both the total cross section and the ratio of the integrated elastic cross section to the total cross section to the total cross section are increasing functions of the center-of-mass energy. Detailed predictions are given for the elastic differential cross sections, Coulomb interference and the ratios of the real to imaginary parts of the forward amplitudes. These predictions have been extensively and accurately confirmed by experiments, and have also been given both for future experiments on existing accelerators and for experiments on future accelerators. 14 refs., 2 figs.
Date: December 31, 1990
Creator: Wu, Tai Tsun
Partner: UNT Libraries Government Documents Department

A tevatron collider beauty factory. [Final report, 1980--1992]

Description: This document which is labeled a final report consists of several different items. The first is a proposal for a detector to be developed for beauty physics. The detector is proposed for the Fermilab Tevatron, and would be designed to measure mixing reactions, rare decay modes, and even CP violation in hadron collider beauty production. The general outline of the work proposed is given, and an estimate of the time to actually design the detector is presented, along with proposed changes to the Tevatron to accommodate the system. A preliminary report on an experiment to verify a reported observation of a 17 keV neutrino in tritium decay is presented. The present results in the decay spectra actually show a depression below expected levels, which is not consistent with a massive neutrino. Additional interest has been shown in finishing an electrostatic beta spectrometer which was started several years previously. The instrument uses hemispherical electrostatic electric fields to retard electrons emitted in tritium decay, allowing measurement of integral spectra. The design goal has a 5 eV energy resolution, which may be achievable. A new PhD student is pursuing this experiment. Also the report contains a proposal for additional work in the field of non-perturbative quantum field theory by the theoretical group at OU. The work which is proposed will be applied to electroweak and strong interactions, as well as to quantum gravitational phenomena.
Date: December 31, 1992
Partner: UNT Libraries Government Documents Department

Space and time correlation in high velocity multiple electron transitions

Description: In collisions of high velocity projectiles of charge Z and velocity v, perturbations expansions in Z/v usually converge when Z/v<l. Under these conditions Z{sup 3} contributions to cross sections for two electron transitions (e.g. double excitation) may arise if there is interference between first order and second order contributions to the probability amplitude. Non-zero Z{sup 3} terms in two electron excitation or ionization cross sections occur if spatial electron correlation is present. For double excitation non-zero Z{sup 3} contributions require a correlation in time as well. This time correlation corresponds to quantum time ordering arising from virtual off-energy-shell intermediate states. As with second order amplitudes for Thomas singularities in single electron capture, the energy non-conserving amplitude is connected to the energy-conserving amplitude in second order in Z by a dispersion relation. Generalization to higher order transitions (e.g. triple excitation) is discussed.
Date: December 31, 1990
Creator: McGuire, J. H. & Straton, J. C.
Partner: UNT Libraries Government Documents Department

Higher twist contributions to lepton-pair production and other QCD processes

Description: A general discussion of the calculations and phenomenological consequences of power-law suppressed QCD processes is given with emphasis on tests in massive lepton pair production. Absolutely normalized predictions are given for the leading twist (transverse current) and higher twist (longitudinal current) contributions to the meson structure function in the region of large x.
Date: December 1, 1982
Creator: Brodsky, S.J.; Berger, E.L. & Lepage, G.P.
Partner: UNT Libraries Government Documents Department

Theoretical Atomic Physics code development IV: LINES, A code for computing atomic line spectra

Description: A new computer program, LINES, has been developed for simulating atomic line emission and absorption spectra using the accurate fine structure energy levels and transition strengths calculated by the (CATS) Cowan Atomic Structure code. Population distributions for the ion stages are obtained in LINES by using the Local Thermodynamic Equilibrium (LTE) model. LINES is also useful for displaying the pertinent atomic data generated by CATS. This report describes the use of LINES. Both CATS and LINES are part of the Theoretical Atomic PhysicS (TAPS) code development effort at Los Alamos. 11 refs., 9 figs., 1 tab.
Date: December 1, 1988
Creator: Abdallah, J. Jr. & Clark, R.E.H.
Partner: UNT Libraries Government Documents Department

The status of strange meson spectroscopy

Description: The present status of strange meson spectroscopy is reviewed with emphasis on the results obtained with the LASS spectrometer at SLAC. The systematics of the level structure are discussed with respect to quark model expectations, and the impact of the proposed KAON Factory on the future of the subject considered. 12 refs., 14 figs.
Date: December 1, 1990
Creator: Dunwoodie, W.
Partner: UNT Libraries Government Documents Department

Nuclear decay studies far-from-stability

Description: Nuclear decay studies far-from-stability are performed not merely to characterize new isotopes, but to establish an experimental footing for improving our theoretical understanding of nuclear structure and decay. Although progress has been made in explaining low-lying level structure for a broad range of nuclei, transition probabilities are not yet quantitatively understood. The ability to understand nuclei far-from-stability is important to astrophysics for extending r- and s-process calculations to unknown nuclei, and to nuclear engineering for decay-heat calculations. Finally, by studying nuclei far-from-stability, we probe extremes of both decay energy and proton-neutron ratios where unforeseen and important new nuclear properties may be exhibited. The decays of nearly 100 isotopes and isomers have been studied with the OASIS mass-separation facility on-line at the Lawrence Berkeley Laboratory SuperHILAC. These studies have concentrated on neutron-deficient nuclei with 55{le}Z{le}71 up to A=157 and neutron-rich nuclei with 166{le}A{le}174. The results of these experiments are combined in this paper with those from many other laboratories to provide insight into systematic trends of beta- and {gamma}-ray transition probabilities near N=82. It is hoped that the smooth systematic trends in these transition probabilities will provide clues towards interpreting the underlying nuclear structure. Nuclei near N=82 and Z=64 are expected to be spherical and should be described by simple Shell Model considerations. Away from the shell closures, deformation sets in which should exhibit itself in the transition probabilities. The Z=64 shell closure is expected to disappear near N=78. The qualitative nature of these phenomena will be discussed.
Date: December 1, 1989
Creator: Firestone, R.B.; Nitschke, J.M.; Wilmarth, P.A.; Vierinen, K.S.; Chasteler, R.M.; Gilat, J. et al.
Partner: UNT Libraries Government Documents Department

Kaon decay amplitudes using staggered fermions

Description: A status report is given of an attempt, using staggered fermions to calculate the real and imaginary parts of the amplitudes for K ..-->.. ..pi pi..,. Semi-quantitative results are found for the imaginary parts, and these suggest that epsilon' might be smaller than previously expected in the standard model.
Date: December 1, 1986
Creator: Sharpe, S.R.
Partner: UNT Libraries Government Documents Department

Is there a hard gluonic contribution to the first moment of g sub 1

Description: We show that the size of the hard gluonic contribution to the first moment of the proton's spin-dependent structure function g{sub 1} is entirely a matter of the convention used in defining the quark distributions. If the UV regulator for the spin-dependent quark distributions respects the gauge invariance of Green's functions (allows shifts of loop momenta) and respects the analyticity structure of the unregulated distributions, then the hard gluonic contribution to the first moment of g{sub 1} vanishes. This is the case, for example, in dimensional regularization. By relaxing the requirement that the regulator allow shifts of loop moments, we are able to obtain a nonvanishing hard gluonic contribution to the first moment of g{sub 1}. However, the first moments of the resulting quark distributions correspond to matrix elements that are either gauge variant or involve nonlocal operators and, hence, have no analogue in the standard operator-product expansion. 11 refs., 2 figs.
Date: December 19, 1990
Creator: Bodwin, G.T. (Argonne National Lab., IL (USA)) & Qiu, Jianwei (State Univ. of New York, Stony Brook, NY (USA). Inst. for Theoretical Physics)
Partner: UNT Libraries Government Documents Department