13,131 research outputs found

    Lattice QCD and Hydro/Cascade Model of Heavy Ion Collisions

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    We report here on a recent lattice study of the QCD transition region at finite temperature and zero chemical potential using domain wall fermions (DWF). We also present a parameterization of the QCD equation of state obtained from lattice QCD that is suitable for use in hydrodynamics studies of heavy ion collisions. Finally, we show preliminary results from a multi-stage hydrodynamics/hadron cascade model of a heavy ion collision, in an attempt to understand how well the experimental data (e.g. particle spectra, elliptic flow, and HBT radii) can constrain the inputs (e.g. initial temperature, freezeout temperature, shear viscosity, equation of state) of the theoretical model.Comment: 10 pages, 12 figures. Proceedings for the 26th Winter Workshop on Nuclear Dynamics, Ocho Rios, Jamaica, Jan 2-9, 201

    Atomic displacements and lattice distortion in the magnetic-field-induced charge ordered state of SmRu4_{4}P12_{12}

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    Structural properties of SmRu4_4P12_{12} in the anomalous magnetic ordered phase between T∗∼14T^*\sim 14 K and TN=16.5T_{\text{N}}=16.5 K in magnetic fields has been studied by x-ray diffraction. Atomic displacements of Ru and P, reflecting the field-induced charge order of the pp electrons, have been deduced by analyzing the intensities of the forbidden Bragg peaks, assuming a cubic space group Pm3ˉPm\bar{3}. Also, by utilizing high-resolution x-ray diffraction experiment, we observed a splitting of fundamental Bragg peaks, clarifying that the unit cell in the magnetic ordered phase is rhombohedral elongated along the [1 1 1][1\, 1\, 1] axis. Responses of the rhombohedral domains to the magnetic field, which reflects the direction of the magnetic moment, is studied in detail.Comment: 11 pages, 11 figures, accepted for publication in PR

    Strain transducers for active control - lumped parameter model

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    Spin Fluid Dynamics Observed by Magnetic Fountain Effect and Mechano-Spin Effect in the Ferromagnetic Superfluid 3^3He A1_1 Phase

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    Systematic observations of the magnetically generated fountain pressure in the superfluid 3^3He A1_1 have been carried out in a newly built apparatus designed to reduce the effect of thermal gradients. In the same apparatus, mechanical pumping and filtering of polarized nuclear spins were realized by the pneumatic pumping action of an electrostatically actuated membrane. In both experiments, the measured induced pressure was observed to decay at all temperatures where the A1_1 phase appeared in magnetic fields up to 13 T and liquid pressures between 1 and 29 bar. The inferred spin relaxation rate tended to increase as the low temperature phase boundary with the A2_2 phase (TC2_{C2}) was approached. The increase in spin relaxation rate near TC2_{C2} can be explained by the presence of a minority spin condensate in the A1_1 phase as predicted by Monien and Tewordt and by the application of the Leggett-Takagi theory of spin relaxation in superfluid 3^3He.Comment: 12 pages, 15 figures, to appear in Physical Review

    New Dissipation Relaxation Phenomenon in Oscillating Solid He-4

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    We describe the first observations on the time-dependent dissipation when the drive level of a torsional oscillator containing solid He-4 is abruptly changed. The relaxation of dissipation in solid He-4 shows rich dynamical behavior including exponential and logarithmic time-dependent decays, hysteresis, and memory effects.Comment: 4 pages, 4 figure

    Oscillation Frequency Dependence of Non-Classical Rotation Inertia of Solid 4^4He

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    The non-classical rotational inertia fraction of the identical cylindrical solid 4^4He below 300 mK is studied at 496 and 1173 Hz by a double resonance torsional oscillator. Below 35 mK, the fraction is the same at sufficiently low rim velocities. Above 35 mK, the fraction is greater for the higher than the lower mode. The dissipation peak of the lower mode occurs at a temperature ∼\sim 4 mK lower than that of the higher mode. The drive dependence of the two modes shows that the reduction of the fraction is characterized by critical velocity, \textit{not} amplitude nor acceleration.Comment: 4 pages, 4 figure

    Coherent center domains from local Polyakov loops

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    We analyze properties of local Polyakov loops using quenched as well as dynamical SU(3) gauge configurations for a wide range of temperatures. It is demonstrated that for both, the confined and the deconfined regime, the local Polyakov loop prefers phase values near the center elements 1, exp(i 2 pi/3), exp(-i 2 pi/3). We divide the lattice sites into three sectors according to these phases and show that the sectors give rise to the formation of clusters. For a suitable definition of these clusters we find that in the quenched case deconfinement manifests itself as the onset of percolation of the clusters. A possible continuum limit of the center clusters is discussed
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