6,814 research outputs found

    Precise Electroweak Measurements at the Z0 Pole

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    Over the last decade, precise LEP and SLC measurements of electroweak coupling parameters at the Z0 pole have lead to tests of the Standard Model to unprecedented precision. This report presents a comprehensive review of these studies, including a review of relevant Z0 pole physics issues, facilities, instrumentation, and the measurements made. Global fits for the Higgs Boson mass and Z0-b coupling parameters are also presented.Comment: LaTex, 17 pages, 9 Postscript figures, uses ws-p8-50x6-00a.cls and epsfig.sty. Submitted to the Proceedings of the 1999 Conference on Physics in Collision, Ann Arbor, Michigan, June 24-26, 199

    Numerical simulation of the turbulent convective buoyant flow of sodium over a backward- facing step

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    A forced convective and a buoyancy-aided turbulent liquid sodium flow over a backward-facing step with a constant heat flux applied on the indented wall is simulated. Linear eddy viscosity models are used for the Reynolds stresses. Turbulent heat fluxes are modelled with a single gradient diffusion hypotheses with two different approaches to evaluate the turbulent Prandtl number. Moreover, the inuence of turbulence on heat transfer to sodium is also assessed through simulations with zero turbulent thermal diffusivity. The results are compared with DNS data from literature. The velocity and turbulent kinetic energy profiles predicted by all models are in good agreement with the DNS data. The local Nusselt number trend is qualitatively well captured, however, its magnitude is underestimated by all models for the mixed convection case. For forced convection, the heat transfer is overestimated by all heat flux models. The simulation with neglected turbulent heat transfer shows the best overall agreement for the forced convection case. For the mixed convection best agreement is obtained using a correlation to locally evaluate the turbulent thermal diffusivity

    Numerical simulation of the turbulent convective buoyant flow of sodium over a backward- facing step

    Get PDF
    A forced convective and a buoyancy-aided turbulent liquid sodium flow over a backward-facing step with a constant heat flux applied on the indented wall is simulated. Linear eddy viscosity models are used for the Reynolds stresses. Turbulent heat fluxes are modelled with a single gradient diffusion hypotheses with two different approaches to evaluate the turbulent Prandtl number. Moreover, the influence of turbulence on heat transfer to sodium is also assessed through simulations with zero turbulent thermal diffusivity. The results are compared with DNS data from literature. The velocity and turbulent kinetic energy profiles predicted by all models are in good agreement with the DNS data. The local Nusselt number trend is qualitatively well captured, however, its magnitude is underestimated by all models for the mixed convection case. For forced convection, the heat transfer is overestimated by all heat flux models. The simulation with neglected turbulent heat transfer shows the best overall agreement for the forced convection case. For the mixed convection best agreement is obtained using a correlation to locally evaluate the turbulent thermal diffusivity

    Ultracold atoms in radio-frequency-dressed potentials beyond the rotating wave approximation

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    We study dressed Bose-Einstein condensates in an atom chip radio-frequency trap. We show that in this system sufficiently strong dressing can be achieved to cause the widely used rotating wave approximation (RWA) to break down. We present a full calculation of the atom - field coupling which shows that the non-RWA contributions quantitatively alter the shape of the emerging dressed adiabatic potentials. The non-RWA contributions furthermore lead to additional allowed transitions between dressed levels. We use RF spectroscopy of Bose-Einstein condensates trapped in the dressed state potentials to directly observe the transition from the RWA to the beyond-RWA regime.Comment: 6 pages, 4 figure

    Evaluation of the storage of diffuse sources of salinity in the Upper Colorado River Basin

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    OWRT project no. B-121-COL

    Dual-species quantum degeneracy of potassium-40 and rubidium-87 on an atom chip

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    In this article we review our recent experiments with a 40K-87Rb mixture. We demonstrate rapid sympathetic cooling of a 40K-87Rb mixture to dual quantum degeneracy on an atom chip. We also provide details on efficient BEC production, species-selective magnetic confinement, and progress toward integration of an optical lattice with an atom chip. The efficiency of our evaporation allows us to reach dual degeneracy after just 6 s of evaporation - more rapidly than in conventional magnetic traps. When optimizing evaporative cooling for efficient evaporation of 87Rb alone we achieve BEC after just 4 s of evaporation and an 8 s total cycle time.Comment: 8 pages, 4 figures. To be published in the Proceedings of the 20th International Conference on Atomic Physics, 2006 (Innsbruck, Austria

    Geomorphology of the middle Mississippi River

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    DBS-SAS-MAS 9.Includes bibliographical references (pages 79-80).Prepared for U.S. Army Engineer Waterways Experiment Station, Corps of Engineers, Vicksburg, Mississippi under Contract No. DACW39-73-C- 0026 by Engineering Research Center, Colorado State University, Fort Collins, Colorado.January 1974.Sponsored by U.S. Army Engineer District, St. Louis
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