104 research outputs found

    Charged particle concepts for fog dispersion

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    Charged particle techniques hold promise for dispersing warm fog in the terminal area of commercial airports. This report focuses on features of the charged particle technique which require further study. The basic physical principles of the technique and the major verification experiments carried out in the past are described. The fundamentals of the nozzle operation are given. The nozzle characteristics and the theory of particle charging in the nozzle are discussed, including information from extensive literature on electrostatic precipitation relative to environmental pollution control and a description of some preliminary reported analyses on the jet characteristics and interaction with neighboring jets. The equation governing the transfer of water substances and of electrical charge is given together with a brief description of several semi-empirical, mathematical expressions necessary for the governing equations. The necessary ingredients of a field experiment to verify the system once a prototype is built are described

    Relativistic Hartree-Bogoliubov description of ground-state properties of Ni and Sn isotopes

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    The Relativistic Hartree Bogoliubov (RHB) theory is applied in the description of ground-state properties of Ni and Sn isotopes. The NL3 parameter set is used for the effective mean-field Lagrangian, and pairing correlations are described by the pairing part of the finite range Gogny interaction D1S. Fully self-consistent RHB solutions are calculated for the Ni (28≀N≀5028\leq N\leq 50) and Sn (50≀N≀8250\leq N\leq 82) isotopes. Binding energies, neutron separation energies, and proton and neutron rmsrms radii are compared with experimental data. The model predicts a reduction of the spin-orbit potential with the increase of the number of neutrons. The resulting energy splittings between spin-orbit partners are discussed, as well as pairing properties calculated with the finite range effective interaction in the pppp channel.Comment: 11 pages, RevTex, 12 p.s figures, submitted to Phys. Rev.

    Proton drip-line nuclei in Relativistic Hartree-Bogoliubov theory

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    Ground-state properties of spherical even-even nuclei 14≀Z≀2814\leq Z \leq 28 and N=18,20,22N=18,20,22 are described in the framework of Relativistic Hartree Bogoliubov (RHB) theory. The model uses the NL3 effective interaction in the mean-field Lagrangian, and describes pairing correlations by the pairing part of the finite range Gogny interaction D1S. Binding energies, two-proton separation energies, and proton rmsrms radii that result from fully self-consistent RHB solutions are compared with experimental data. The model predicts the location of the proton drip-line. The isospin dependence of the effective spin-orbit potential is discussed, as well as pairing properties that result from the finite range interaction in the pppp channel.Comment: 12 pages, RevTex, 10 p.s figures, submitted to Phys. Rev.

    Testing the Meson Cloud Model in Inclusive Meson Production

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    We have applied the Meson Cloud Model to calculate inclusive momentum spectra of pions and kaons produced in high energy proton-proton and proton-nucleus collisions. For the first time these data are used to constrain the cloud cut-off parameters. We show that it is possible to obtain a reasonable description of data, especially the large xFx_F (xF≄0.2x_F \geq 0.2) part of the spectrum and at the same time describe (partially) the E866 data on dˉ−uˉ\bar d - \bar u and dˉ/uˉ\bar d / \bar u. We also discuss the relative strength of the πN\pi N and πΔ\pi \Delta vertices. We find out that the corresponding cut-off parameters should be both soft and should not differ by more than 200 MeV from each other. An additional source (other than the meson cloud) of sea antiquark asymmetry, seems to be necessary to completely explain the data. A first extension of the MCM to proton nucleus collisions is discussed.Comment: 14 pages, Latex, 6 ps figures. Submitted to Phys. Rev.

    K* nucleon hyperon form factors and nucleon strangeness

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    A crucial input for recent meson hyperon cloud model estimates of the nucleon matrix element of the strangeness current are the nucleon-hyperon-K* (NYK*) form factors which regularize some of the arising loops. Prompted by new and forthcoming information on these form factors from hyperon-nucleon potential models, we analyze the dependence of the loop model results for the strange-quark observables on the NYK* form factors and couplings. We find, in particular, that the now generally favored soft N-Lambda-K* form factors can reduce the magnitude of the K* contributions in such models by more than an order of magnitude, compared to previous results with hard form factors. We also discuss some general implications of our results for hadronic loop models.Comment: 9 pages, 8 figures, new co-author, discussion extended to the momentum dependence of the strange vector form factor

    Nucleon Structure and Parity-Violating Electron Scattering

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    We review the area of strange quark contributions to nucleon structure. In particular, we focus on current models of strange quark vector currents in the nucleon and the associated parity-violating elastic electron scattering experiments from which vector- and axial-vector currents are extractedComment: 40 pages including 7 figures; review article to be published in Int. J. Mod. Phys.

    Electromagnetic Form Factors of the Nucleon in an Improved Quark Model

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    Nucleon electromagnetic form factors are studied in the cloudy bag model (CBM) with center-of-mass and recoil corrections. This is the first presentation of a full set of nucleon form factors using the CBM. The center of mass motion is eliminated via several different momentum projection techniques and the results are compared. It is found that the shapes of these form factors are significantly improved with respect to the experimental data if the Lorentz contraction of the internal structure of the baryon is also appropriately taken into account.Comment: revtex, 28 pages, 8 ps figs include

    Time-odd components in the mean field of rotating superdeformed nuclei

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    Rotation-induced time-odd components in the nuclear mean field are analyzed using the Hartree-Fock cranking approach with effective interactions SIII, SkM*, and SkP. Identical dynamical moments J(2){{\cal J}^{(2)}} are obtained for pairs of superdeformed bands 151^{151}Tb(2)--152^{152}Dy(1) and 150^{150}Gd(2)--151^{151}Tb(1). The corresponding relative alignments strongly depend on which time-odd mean-field terms are taken into account in the Hartree-Fock equations.Comment: 23 pages, ReVTeX, 6 uuencoded postscript figures include

    Meson exchange and nucleon polarizabilities in the quark model

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    Modifications to the nucleon electric polarizability induced by pion and sigma exchange in the q-q potentials are studied by means of sum rule techniques within a non-relativistic quark model. Contributions from meson exchange interactions are found to be small and in general reduce the quark core polarizability for a number of hybrid and one-boson-exchange q-q models. These results can be explained by the constraints that the baryonic spectrum impose on the short range behavior of the mesonic interactions.Comment: 11 pages, 1 figure added, expanded discussio

    A STRANGE MESONIC TRANSITION FORM FACTOR

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    The strange-quark vector current ρ\rho-to-π\pi meson transition form factor is computed at one-loop order using strange meson intermediate states. A comparison is made with a ϕ\phi-meson dominance model estimate. We find that one-loop contributions are comparable in magnitude to those predicted by ϕ\phi-meson dominance. It is possible that the one-loop contribution can make the matrix element as large as those of the electromagnetic current mediating vector meson radiative decays. However, due to the quadratic dependence of the one-loop results on the hadronic form factor cut-off mass, a large uncertainty in the estimate of the loops is unavoidable. These results indicate that non-nucleonic strange quarks could contribute appreciably in moderate-∣Q2∣|Q^2| parity-violating electron-nucleus scattering measurements aimed at probing the strange-quark content of the nucleon.Comment: Revtex, six figures available as hard copy upon request
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