The CMS experiment workflows on StoRM based storage at Tier-1 and Tier-2 centers

Approaching LHC data taking, the CMS experiment is deploying, commissioning and operating the building tools of its grid-based computing infrastructure. The commissioning program includes testing, deployment and operation of various storage solutions to support the computing workflows of the experiment. Recently, some of the Tier-1 and Tier-2 centers supporting the collaboration have started to deploy StoRM based storage systems. These are POSIX-based disk storage systems on top of which StoRM implements the Storage Resource Manager (SRM) version 2 interface allowing for a standard-based access from the Grid. In this notes we briefly describe the experience so far achieved at the CNAF Tier-1 center and at the IFCA Tier-2 center

Polarization-correlated photon pairs from a single ion

In the fluorescence light of a single atom, the probability for emission of a photon with certain polarization depends on the polarization of the photon emitted immediately before it. Here correlations of such kind are investigated with a single trapped calcium ion by means of second order correlation functions. A theoretical model is developed and fitted to the experimental data, which show 91% probability for the emission of polarization-correlated photon pairs within 24 ns.Comment: 8 pages, 9 figure

Rotational dynamics in the plastic-crystal phase of ethanol: Relevance for understanding the dynamics during the structural glass transition

The reorientational dynamics within the rotationally disordered cubic plastic phase of solid ethanol is investigated by means of the concurrent use of computer molecular dynamics and quasielastic neutron scattering. Motions involving widely different time scales are shown to take place above the calorimetric "glass transition" which is centered at Tg≈97 K. These correspond to well-defined reorientations belonging to the cubic point group. The dynamics of this solid exhibits features remarkably close to those of the supercooled liquid that can exist at the same temperature. Such similitude of dynamic behavior serves to provide some clues for the understanding of the nature of molecular motions at temperatures close to the canonical liquid→glass transitio

Mercado nacional de ganados en Torrelavega. España

The roof of this Market received one of the awards granted by SERCOMENTAL to the best metal constructions. All roofing has a three-dimensional reticular structural system. Among the several possible structural solutions for the very large main hall (250 m X 60 m), the one chosen was a circular running axis vault, having the advantage over the funicular valt that all tubes are of equal length. The fiat three-dimensional structures maintain the same 1.50 x 1.64 m mesh size, but changing the height from 1.50 m. In the hall nº 2 to 1 m in the canopy. This work stands out for its visual lightness and aesthetic valué as well as for the simplicity of the materials used (tubes and spheres) and the solution of the nodes and mounting methods.Las cubiertas de este mercado obtuvieron uno de los premios a las mejores construcciones metálicas otorgados por Sercometal. Todas las cubiertas tienen una estructura reticulada espacial. Entre las posibles soluciones estructurales para la nave principal, que tiene una notable magnitud (250 x 60 m), se eligió la de una bóveda de directriz circular, cuya ventaja sobre la funicular es que todos los tubos tienen la misma longitud. Las estructuras espaciales planas llevan la misma malla de 1,50 x 1,64 m, pero variando el canto de 1,50 m en la nave n.° 2 a 1 m en la marquesina. Destaca en esta obra su ligereza y valor estético, así como la simplicidad de los materiales utilizados (esferas y tubos) y la ejecución de los nudos y el montaje

Control the entanglement of two atoms in an optical cavity via white noise

Two two-level atoms within a leaky optical cavity is driven by two independent external optical white noise fields. We investigate how entanglement between two atoms arises in such a situation. The steady state entanglement of two atoms is also investigated. A stochastic-resonance-like behavior of entanglement is revealed. Finally, the Bell violation between atoms is discussed.Comment: 10 pages, 9 figure

Rotational dynamics in the plastic-crystal phase of ethanol: Relevance for understanding the dynamics during the structural glass transition

12 págs.; 14 figs.; 1 tab.; 1 apéndiceThe reorientational dynamics within the rotationally disordered cubic plastic phase of solid ethanol is investigated by means of the concurrent use of computer molecular dynamics and quasielastic neutron scattering. Motions involving widely different time scales are shown to take place above the calorimetric >glass transition> which is centered at Tg≈97 K. These correspond to well-defined reorientations belonging to the cubic point group. The dynamics of this solid exhibits features remarkably close to those of the supercooled liquid that can exist at the same temperature. Such similitude of dynamic behavior serves to provide some clues for the understanding of the nature of molecular motions at temperatures close to the canonical liquid→glass transition. ©2000 The American Physical Society.This work was supported in part by Grant No. DGICYTPB95- 0072-C03 (Spain). Work at ANL was supported by the U.S. Department of Energy, BES–Materials Sciences, under Contract No. W-31-109-ENG-38.Peer Reviewe

Role of low-frequency vibrations on sound propagation in glasses at intermediate temperature

We report measurements of the temperature dependence of the sound attenuation and the fractional change in sound velocity for the glass (G) and orientational-glass (OG) phases of polymorphic ethanol. Strikingly similar behaviors are found for both phases despite the OG's underlying crystal (bcc) lattice. Such similarity, which is also revealed in dielectric spectroscopy and inelastic neutron scattering measurements, suggests whole molecule small-angle librations as a common microscopic origin for a wide variety of "glassy" phenomena.Dirección General de Investigación Científica y Técnica PB95-0075-C03-0

Nonclassical Interference Effects In The Radiation From Coherently Driven Uncorrelated Atoms

We demonstrate the existence of new nonclassical correlations in the radiation of two atoms, which are coherently driven by a continuous laser source. The photon-photon-correlations of the fluorescence light show a spatial interferene pattern not present in a classical treatment. A feature of the new phenomenon is, that bunched and antibunched light is emitted in different spatial directions. The calculations are performed analytically. It is pointed out, that the correlations are induced by state reduction due to the measurement process when the detection of the photons does not distinguish between the atoms. It is interesting to note, that the phenomena show up even without any interatomic interaction.Comment: 4 pages, 6 Figure