131 research outputs found

    Emergence of superfluid transport in a dynamical system of ultracold atoms

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    The dynamics of a Bose-Einstein condensate is studied theoretically in a combined periodic plus harmonic external potential. Different dynamical regimes of stable and unstable collective dipole and Bloch oscillations are analysed in terms of a quantum mechanical pendulum model. Nonlinear interactions are shown to counteract quantum-mechanical dephasing and lead to phase-coherent, superfluid transport

    A description of the ratio between electric and magnetic proton form factors by using space-like, time-like data and dispersion relations

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    We use the available information on the ratio between the electric and magnetic proton form factors coming from recently published space-like data and from the few available time-like data. We apply a dispersive procedure on these data to evaluate the behaviour of this ratio, as a complex function, for all values of q^2.Comment: 12 pages, 7 Encapsulated Postscript figures, uses epsfig, rotating, exscale, amsmath, cite, latexsym, graphics, color packages, added reference

    Measurement of the LT-asymmetry in \pi^0 electroproduction at the energy of the \Delta (1232) resonance

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    The reaction p(e,e'p)pi^0 has been studied at Q^2=0.2 (GeV/c)^2 in the region of W=1232 MeV. From measurements left and right of q, cross section asymmetries \rho_LT have been obtained in forward kinematics \rho_LT(\theta_\pi^0=20deg) = (-11.68 +/- 2.36_stat +/- 2.36_sys)$ and backward kinematics \rho_LT(\theta_\pi^0=160deg) =(12.18 +/- 0.27_stat +/- 0.82_sys). Multipole ratios \Re(S_1+^* M_1+)/|M_1+|^2 and \Re(S_0+^* M_1+)/|M_1+|^2 were determined in the framework of the MAID2003 model. The results are in agreement with older data. The unusally strong negative \Re(S_0+^* M_1+)/|M_1+|^2 required to bring also the result of Kalleicher et al. in accordance with the rest of the data is almost excluded.Comment: 7 pages, 7 figures, 4 tables. Changed content. Accepted for publication in EPJ

    Economic assessment of use of pond ash in pavements

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    The paper introduces a new type of industrial waste-based subbase material which can replace conventional subbase material (CSM) in pavement construction. Utilisation of this industrial waste, namely pond coal ash produced from a thermal power plant in road construction will help to reduce the disposal problem of this waste and also will help to reduce the problem of scarcity of CSM. Lime and fibre were also added to the pond ash at various percentages to improve the suitability of this type of mix as subbase material. The optimum service life of pavement is studied with the help of numerical modelling and the cost benefit is also presented in the current study. The study reveals that stabilisation of the coal ash with 2% lime may produce an optimal material and, even though a greater thickness may be required to deliver the same pavement performance, direct cost savings of around 10% may be achieved in addition to less easily quantifiable environmental benefits. Design charts are provided to exploit the findings

    Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV

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    We report the first measurement of charged particle elliptic flow in Pb-Pb collisions at 2.76 TeV with the ALICE detector at the CERN Large Hadron Collider. The measurement is performed in the central pseudorapidity region (|η\eta|<0.8) and transverse momentum range 0.2< pTp_{\rm T}< 5.0 GeV/cc. The elliptic flow signal v2_2, measured using the 4-particle correlation method, averaged over transverse momentum and pseudorapidity is 0.087 ±\pm 0.002 (stat) ±\pm 0.004 (syst) in the 40-50% centrality class. The differential elliptic flow v2(pT)_2(p_{\rm T}) reaches a maximum of 0.2 near pTp_{\rm T} = 3 GeV/cc. Compared to RHIC Au-Au collisions at 200 GeV, the elliptic flow increases by about 30%. Some hydrodynamic model predictions which include viscous corrections are in agreement with the observed increase.Comment: 10 pages, 4 captioned figures, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/389

    High-Frequency (>100 GHz) and High-Speed (<1 ps) Electronic Devices

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    Contains an introduction, reports on three research projects and a list of publications.Advanced Research Projects Agency Contract MDA972-90-C-0021National Aeronautics and Space Administration Grant NAG2-693National Aeronautics and Space Administration Contract 959705National Science Foundation/MRSEC Grant DMR 94-00334MIT Lincoln Laboratory Advanced Concept Program Contract BX-5464MIT Research Laboratory of Electronics Postdoctoral FellowshipRome Air Force Laboratory Graduate FellowshipU.S. Army Research Office Grant DAAL03-92-G-0251Hertz Foundation FellowshipU.S. Army Research Office/ASSERT Grant DAAH04-94-G-016

    Higher harmonic anisotropic flow measurements of charged particles in Pb-Pb collisions at 2.76 TeV

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    We report on the first measurement of the triangular v3v_3, quadrangular v4v_4, and pentagonal v5v_5 charged particle flow in Pb-Pb collisions at 2.76 TeV measured with the ALICE detector at the CERN Large Hadron Collider. We show that the triangular flow can be described in terms of the initial spatial anisotropy and its fluctuations, which provides strong constraints on its origin. In the most central events, where the elliptic flow v2v_2 and v3v_3 have similar magnitude, a double peaked structure in the two-particle azimuthal correlations is observed, which is often interpreted as a Mach cone response to fast partons. We show that this structure can be naturally explained from the measured anisotropic flow Fourier coefficients.Comment: 10 pages, 4 figures, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/387

    Physics of the HL-LHC, and Perspectives at the HE-LHC

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