2,333 research outputs found

    Dielectric Response in Microscopically Heterogeneous Dielectrics: Example of KTaO_3:Nb

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    New experimental data on solid solutions of quantum paraelectrics with KTaO_3:Nb as an example are considered within a framework of a quantum theory of ferroelectric phase transitions. In order to describe the effect of local heterogeneities a percolation type theory together with a random field approach were employed.Comment: 4 figure

    Preliminary Results on gamma gamma -> Ks K pi from CLEO

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    We analyzed 13.8 fb^{-1} of the integrated e+e- luminosity collected at 10.6 GeV center-of-mass energy with the CLEO II and II.V detectors to study exclusive two-photon production of single hadronic resonances. We searched for hadrons decaying into Ks K pi when both leptons remain undetected. In this analysis we studied the detection efficiency and evaluated systematic errors using independent data samples. We estimated 90% CL upper limits on the products of the two-photon partial widths of (pseudo)scalar hadrons with masses below 1.7 GeV/c2 and their branching fractions into Ks K pi. Our preliminary results are marginally consistent with the first observation of eta(1440) in two-photon collisions by the L3 experiment.Comment: 4 pages, 1 figure, proceedings contribution for PANIC'0

    In situ visualization of Ni-Nb bulk metallic glasses phase transition

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    We report the results of the Ni-based bulk metallic glass structural evolution and crystallization behavior in situ investigation. The X-ray diffraction (XRD), transmission electron microscopy (TEM), nano-beam diffraction (NBD), differential scanning calorimetry (DSC), radial distribution function (RDF) and scanning probe microscopy/spectroscopy (STM/STS) techniques were applied to analyze the structure and electronic properties of Ni63.5Nb36.5 glasses before and after crystallization. It was proved that partial surface crystallization of Ni63.5Nb36.5 can occur at the temperature lower than for the full sample crystallization. According to our STM measurements the primary crystallization is originally starting with the Ni3Nb phase formation. It was shown that surface crystallization drastically differs from the bulk crystallization due to the possible surface reconstruction. The mechanism of Ni63.5Nb36.5 glass alloy 2D-crystallization was suggested, which corresponds to the local metastable (3x3)-Ni(111) surface phase formation. The possibility of different surface nano-structures development by the annealing of the originally glassy alloy in ultra high vacuum at the temperature lower, than the crystallization temperature was shown. The increase of mean square surface roughness parameter Rq while moving from glassy to fully crystallized state can be caused by concurrent growth of Ni3Nb and Ni6Nb7 bulk phases. The simple empirical model for the estimation of Ni63.5Nb36.5 cluster size was suggested, and the obtained values (7.64 A, 8.08 A) are in good agreement with STM measurements data (8 A-10 A)

    Upcoming Revolution with the LHC

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    Sensitivity to various BSM physics scenarios with the ALTAS and CMS detectors at the LHC is discusse
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