5,620 research outputs found

    Resistojet systems studies directed to the space station/space base. Volume 2 - Biowaste resistojet system development program Final report

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    Space station/base biowaste resistojet system for orbit keeping and control moment gyro desaturation - systems developmen

    Isospin emission and flows at high baryon density: a test of the symmetry potential

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    High energy Heavy Ion Collisions (HIC) are studied in order to access nuclear matter properties at high density. Particular attention is paid to the selection of observables sensitive to the poorly known symmetry energy at high baryon density, of large fundamental interest, even for the astrophysics implications. Using fully consistent transport simulations built on effective theories we test isospin observables ranging from nucleon/cluster emissions to collective flows (in particular the elliptic, squeeze out, part). The effects of the competition between stiffness and momentum dependence of the Symmetry Potential on the reaction dynamics are thoroughly analyzed. In this way we try to shed light on the controversial neutron/proton effective mass splitting at high baryon and isospin densities. New, more exclusive, experiments are suggested.Comment: 10 pages, 16 figures, new figure added, accepted for publication in Phys.Rev.

    Isospin emission and flows at high baryon density: a test of the symmetry potential

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    High energy Heavy Ion Collisions (HIC) are studied in order to access nuclear matter properties at high density. Particular attention is paid to the selection of observables sensitive to the poorly known symmetry energy at high baryon density, of large fundamental interest, even for the astrophysics implications. Using fully consistent transport simulations built on effective theories we test isospin observables ranging from nucleon/cluster emissions to collective flows (in particular the elliptic, squeeze out, part). The effects of the competition between stiffness and momentum dependence of the Symmetry Potential on the reaction dynamics are thoroughly analyzed. In this way we try to shed light on the controversial neutron/proton effective mass splitting at high baryon and isospin densities. New, more exclusive, experiments are suggested.Comment: 10 pages, 16 figures, new figure added, accepted for publication in Phys.Rev.

    Comparison of dynamical multifragmentation models

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    Multifragmentation scenarios, as predicted by antisymmetrized molecular dynamics (AMD) or momentum-dependent stochastic mean-field (BGBD) calculations are compared. While in the BGBD case fragment emission is clearly linked to the spinodal decomposition mechanism, i.e. to mean-field instabilities, in AMD many-body correlations have a stronger impact on the fragmentation dynamics and clusters start to appear at earlier times. As a consequence, fragments are formed on shorter time scales in AMD, on about equal footing of light particle pre-equilibrium emission. Conversely, in BGBD pre-equilibrium and fragment emissions happen on different time scales and are related to different mechanisms

    On the spin-isospin decomposition of nuclear symmetry energy

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    The decomposition of nuclear symmetry energy into spin and isospin components is discussed to elucidate the underlying properties of the NN bare interaction. This investigation was carried out in the framework of the Brueckner-Hartree-Fock theory of asymmetric nuclear matter with consistent two and three body forces. It is shown the interplay among the various two body channels in terms of isospin singlet and triplet components as well as spin singlet and triplet ones. The broad range of baryon densities enables to study the effects of three body force moving from low to high densities.Comment: 8 pages, 4 figure

    Hadron production from quark coalescence and jet fragmentation in intermediate energy collisions at RHIC

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    Transverse momentum spectra of pions, protons and antiprotons in Au+Au collisions at intermediate RHIC energy of sNN=62\sqrt{s_{NN}}=62 GeV are studied in a model that includes both quark coalescence from the dense partonic matter and fragmentation of the quenched perturbative minijet partons. The resulting baryon to meson ratio at intermediate transverse momenta is predicted to be larger than that seen in experiments at higher center of mass energies.Comment: 6 pages, 2 figures. Figures replaced to differentially address the high-pT behavior of baryon versus antibaryon to meson ratio

    Transport properties of isospin effective mass splitting

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    We investigate in detail the momentum dependence (MDMD) of the effective in medium Nucleon-Nucleon (NNNN) interaction in the isovector channel. We focus the discussion on transport properties of the expected neutron-proton (n/pn/p) effective mass splitting at high isospin density. We look at observable effects from collective flows in Heavy Ion Collisions (HICHIC) of charge asymmetric nuclei at intermediate energies. Using microscopic kinetic equation simulations nucleon transverse and elliptic collective flows in Au+AuAu+Au collisions are evaluated. In spite of the reduced charge asymmetry of the interacting system interesting isospinMDisospin-MD effects are revealed. Good observables, particularly sensitive to the n/pn/p-mass splitting, appear to be the differences between neutron and proton flows. The importance of more exclusive measurements, with a selection of different bins of the transverse momenta (ptp_t) of the emitted particles, is stressed. In more inclusive data a compensation can be expected from different ptp_t-contributions, due to the microscopic isospinMDisospin-MD structure of the nuclear mean field in asymmetric matter.Comment: 18 pages, 11 figure
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