1,832 research outputs found

    Al-Substitution Effects on Physical Properties of the Colossal Magnetoresistance Compouns La0.67ca0.33mno3

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    We present a detailed study of the polycrystalline perovskite manganites La0.67Ca0.33AlxMn1-xO3 (x = 0, 0.1, 0.15, 0.5) at low temperatures and high magnetic fields, including electrical resistance, magnetization, ac susceptibility. The static magnetic susceptibility was also measured up to 1000 K. All the samples show colossal magnetoresistance behavior and the Curie temperatures decrease with Al doping. The data suggest the presence of correlated magnetic clusters near by the ferromagnetic transition. This appears to be a consequence of the structural and magnetic disorder created by the random distribution of Al atoms.Comment: 13 pages including 5 figure

    A new technique for the reconstruction, validation, and simulation of hits in the CMS Pixel Detector

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    This note describes new techniques for the reconstruction/validation and the simulation of pixel hits. The techniques are based upon the use of pre-computed projected cluster shapes or ``templates''. A detailed simulation called Pixelav that has successfully described the profiles of clusters measured in beam tests of radiation-damaged sensors is used to generate the templates. Although the reconstruction technique was originally developed to optimally estimate the coordinates of hits after the detector became radiation damaged, it also has superior performance before irradiation. The technique requires a priori knowledge of the track angle which makes it suitable for the second in a two-pass reconstruction algorithm. However, the same modest angle sensitivity allows the algorithm to determine if the sizes and shapes of the cluster projections are consistent with the input angles. This information may be useful in suppressing spurious hits caused by secondary particles and in validating seeds used in track finding. The seed validation is currently under study but has the potential to significantly increase the speed of track finding in the offline reconstruction. Finally, a new procedure that uses the templates to re-weight clusters generated by the CMSSW simulation is described. The first tests of this technique are encouraging and when fully implemented, the technique will enable the fast simulation of pixel hits that have the characteristics of the much more CPU-intensive Pixelav hits. In particular, it may be the only practical technique available to simulate hits from a radiation damaged detector in CMSSW

    Insights into the raw materials and technology used to produce Copper Age ceramics in the Southern Carpathians (Romania)

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    © 2016, Springer-Verlag Berlin Heidelberg. The Copper Age Coţofeni culture occupied a large territory which covers present day W Romania, NE Serbia, and NW Bulgaria. The Coțofeni people lived in settlements located on hill slopes and river terraces, as well as in caves. Their hand-modeled ceramic pottery is richly ornamented by incisions, incrustations, and “lentil bean” appliqués. Potsherds found in the “Peştera Mare de la Cerişor” (i.e., the “Great Cave of Cerişor”) located in Paleozoic crystalline limestones and dolomites (Southern Carpathians, Romania) were studied in terms of mineralogy and petrography by OM, XRD, and EMPA. The sherds consist of an Fe-rich illitic matrix embedding quartz, K-feldspar, muscovite, plagioclase, biotite, chlorite, various heavy minerals, metamorphic, magmatic and sedimentary lithoclasts, as well as soil concretions and chamotte. Within a temperature interval, spanning between ∼800 and ∼900 °C, three firing groups were roughly separated, based on the optical characteristics of the matrix and the intensity of the illite/muscovite diffraction peaks. Quaternary and Miocene rocks from the area were analyzed by XRD in order to determine the provenance of the raw materials

    Vision Bus Aotearoa: a platform for strengthening eye health teaching, research and community partnership

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    CLINICAL RELEVANCE: Vision Bus Aotearoa is a fully equipped mobile eye health clinic designed to provide a novel platform for undergraduate optometry clinical training, community eye health research and deliver services to underserved communities. BACKGROUND: Aotearoa New Zealand has inequitable access to eye health care. Vision Bus Aotearoa aims to work in partnership with communities to provide comprehensive mobile primary eye health care services while training optometry students, and integrating community eye health research. METHODS: A description is provided of the governance model which has been involved throughout the project. RESULTS: The process of vehicle manufacture, clinical set-up, funding models and service delivery are described. The aims of the project are detailed in terms of optometry teaching, clinical services in partnership with communities, and research integration and implementation. CONCLUSION: Vision Bus Aotearoa represents a valuable opportunity to deliver mobile eye health care to historically underserved communities, enhance undergraduate optometry teaching and to provide a unique platform for community eye health research

    Measurement of neutrino velocity with the MINOS detectors and NuMI neutrino beam

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    The velocity of a ~3 GeV neutrino beam is measured by comparing detection times at the near and far detectors of the MINOS experiment, separated by 734 km. A total of 473 far detector neutrino events was used to measure (v-c)/c=5.12.910-5 (at 68% C.L.). By correlating the measured energies of 258 charged-current neutrino events to their arrival times at the far detector, a limit is imposed on the neutrino mass of mnu<50 MeV/c2 (99% C.L.)

    Measurement of the Atmospheric Muon Charge Ratio at TeV Energies with MINOS

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    The 5.4 kton MINOS far detector has been taking charge-separated cosmic ray muon data since the beginning of August, 2003 at a depth of 2070 meters-water-equivalent in the Soudan Underground Laboratory, Minnesota, USA. The data with both forward and reversed magnetic field running configurations were combined to minimize systematic errors in the determination of the underground muon charge ratio. When averaged, two independent analyses find the charge ratio underground to be 1.374 +/- 0.004 (stat.) +0.012 -0.010(sys.). Using the map of the Soudan rock overburden, the muon momenta as measured underground were projected to the corresponding values at the surface in the energy range 1-7 TeV. Within this range of energies at the surface, the MINOS data are consistent with the charge ratio being energy independent at the two standard deviation level. When the MINOS results are compared with measurements at lower energies, a clear rise in the charge ratio in the energy range 0.3 -- 1.0 TeV is apparent. A qualitative model shows that the rise is consistent with an increasing contribution of kaon decays to the muon charge ratio.Comment: 16 pages, 17 figure

    Precise measurement of the W-boson mass with the CDF II detector

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    We have measured the W-boson mass MW using data corresponding to 2.2/fb of integrated luminosity collected in proton-antiproton collisions at 1.96 TeV with the CDF II detector at the Fermilab Tevatron collider. Samples consisting of 470126 W->enu candidates and 624708 W->munu candidates yield the measurement MW = 80387 +- 12 (stat) +- 15 (syst) = 80387 +- 19 MeV. This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined

    Search for Neutral Higgs Bosons in Events with Multiple Bottom Quarks at the Tevatron

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    The combination of searches performed by the CDF and D0 collaborations at the Fermilab Tevatron Collider for neutral Higgs bosons produced in association with b quarks is reported. The data, corresponding to 2.6 fb-1 of integrated luminosity at CDF and 5.2 fb-1 at D0, have been collected in final states containing three or more b jets. Upper limits are set on the cross section multiplied by the branching ratio varying between 44 pb and 0.7 pb in the Higgs boson mass range 90 to 300 GeV, assuming production of a narrow scalar boson. Significant enhancements to the production of Higgs bosons can be found in theories beyond the standard model, for example in supersymmetry. The results are interpreted as upper limits in the parameter space of the minimal supersymmetric standard model in a benchmark scenario favoring this decay mode.Comment: 10 pages, 2 figure

    Search for the standard model Higgs boson decaying to a bbˉb\bar{b} pair in events with no charged leptons and large missing transverse energy using the full CDF data set

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    We report on a search for the standard model Higgs boson produced in association with a vector boson in the full data set of proton-antiproton collisions at s=1.96\sqrt{s} = 1.96 TeV recorded by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45 fb1^{-1}. We consider events having no identified charged lepton, a transverse energy imbalance, and two or three jets, of which at least one is consistent with originating from the decay of a bb quark. We place 95% credibility level upper limits on the production cross section times standard model branching fraction for several mass hypotheses between 90 and 150GeV/c2150 \mathrm{GeV}/c^2. For a Higgs boson mass of 125GeV/c2125 \mathrm{GeV}/c^2, the observed (expected) limit is 6.7 (3.6) times the standard model prediction.Comment: Accepted by Phys. Rev. Let

    Search for the standard model Higgs boson decaying to a bb pair in events with one charged lepton and large missing transverse energy using the full CDF data set

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    We present a search for the standard model Higgs boson produced in association with a W boson in sqrt(s) = 1.96 TeV p-pbar collision data collected with the CDF II detector at the Tevatron corresponding to an integrated luminosity of 9.45 fb-1. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the W boson to an electron or muon and a neutrino, we set 95% credibility level upper limits on the WH production cross section times the H->bb branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125 GeV/c2 we observe (expect) a limit of 4.9 (2.8) times the standard model value.Comment: Submitted to Phys. Rev. Lett (v2 contains clarifications suggested by PRL
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