202,048 research outputs found

    The relativistic continuum Hartree-Bogoliubov description of charge-changing cross section for C,N,O and F isotopes

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    The ground state properties including radii, density distribution and one neutron separation energy for C, N, O and F isotopes up to the neutron drip line are systematically studied by the fully self-consistent microscopic Relativistic Continuum Hartree-Bogoliubov (RCHB) theory. With the proton density distribution thus obtained, the charge-changing cross sections for C, N, O and F isotopes are calculated using the Glauber model. Good agreement with the data has been achieved. The charge changing cross sections change only slightly with the neutron number except for proton-rich nuclei. Similar trends of variations of proton radii and of charge changing cross sections for each isotope chain is observed which implies that the proton density plays important role in determining the charge-changing cross sections.Comment: 10 pages, 4 figure

    The surface diffuseness and the spin-orbital splitting in relativistic continuum Hartree-Bogoliubov theory

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    The Relativistic Continuum Hartree Bogoliubov theory (RCHB), which is the extension of the Relativistic Mean Field and the Bogoliubov transformation in the coordinate representation, has been used to study tin isotopes. The pairing correlation is taken into account by a density-dependent force of zero range. RCHB is used to describe the even-even tin isotopes all the way from the proton drip line to the neutron drip line. The contribution of the continuum which is important for nuclei near the drip-line has been taken into account. The theoretical S2nS_{2n} as well as the neutron, proton, and matter rmsrms radii are presented and compared with the experimental values where they exist. The change of the potential surface with the neutron number has been investigated. The diffuseness of the potentials in tin isotopes is analyzed through the spin-orbital splitting in order to provide new way to understand the halo phenomena in exotic nuclei. The systematic of the isospin and energy dependence of these results are extracted and analyzed.Comment: 11 figure

    Lorentz Group and Oriented MICZ-Kepler Orbits

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    The MICZ-Kepler orbits are the non-colliding orbits of the MICZ Kepler problems (the magnetized versions of the Kepler problem). The oriented MICZ-Kepler orbits can be parametrized by the canonical angular momentum L\mathbf L and the Lenz vector A\mathbf A, with the parameter space consisting of the pairs of 3D vectors (A,L)(\mathbf A, \mathbf L) with Lβ‹…L>(Lβ‹…A)2{\mathbf L}\cdot {\mathbf L} > (\mathbf L\cdot \mathbf A)^2. The recent 4D perspective of the Kepler problem yields a new parametrization, with the parameter space consisting of the pairs of Minkowski vectors (a,l)(a,l) with lβ‹…l=βˆ’1l\cdot l =-1, aβ‹…l=0a\cdot l =0, a0>0a_0>0. This new parametrization of orbits implies that the MICZ-Kepler orbits of different magnetic charges are related to each other by symmetries: \emph{SO+(1,3)Γ—R+{\mathrm {SO}}^+(1,3)\times {\mathbb R}_+ acts transitively on both the set of oriented elliptic MICZ-Kepler orbits and the set of oriented parabolic MICZ-Kepler orbits}. This action extends to O+(1,3)Γ—R+{\mathrm {O}}^+(1,3)\times {\mathbb R}_+, the \emph{structure group} for the rank-two Euclidean Jordan algebra whose underlying Lorentz space is the Minkowski space.Comment: 7 page

    On pluricanonical maps for threefolds of general type, II

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    This note mainly studies the generic finiteness of \phi_m of a complex projective 3-fold of general type. A new result on the classification to bicanonical pencil for Gorenstein 3-folds is attached in the last section.Comment: 16 pages, Amstex, The final version, Accepted for publication in Osaka Journal of Mathematic

    The Stability of the Steady State and Bistable Response of a Flexible Rotor Supported on Squeeze Film Dampers

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    The stability of the steady state response, the bistable response, and the jumping characteristics are analyzed for the case when a system accelerates or decelerates through the bistable region of a flexible rotor-centralized squeeze film damper system. It was found that the system steady state responses have two unstable regions. The larger the unbalance parameter and the smaller the bearing parameter and the external damping ratio, the easier it is for the system to lose stability. The larger the mass ratio and the smaller the stiffness ratio, the lower the threshold rotating speed of instability. The instability of the system steady-state response determined here is due to the system nonsynchronous response in many cases
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