4,636 research outputs found

    Recent Results from the MINOS experiment

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    MINOS is an accelerator neutrino oscillation experiment at Fermilab. An intense high energy neutrino beam is produced at Fermilab and sent to a near detector on the Fermilab site and also to a 5 kTon far detector 735 km away in the Soudan mine in northern Minnesota. The experiment has now had several years of running with millions of events in the near detector and hundreds of events recorded in the far detector. I will report on the recent results from this experiment which include precise measurement of Δm322|\Delta m^2_{32}|, ~analysis of neutral current data to limit the component of sterile neutrinos, and the search for νμνe\nu_\mu \to \nu_e conversion. The focus will be on the analysis of data for νμνe\nu_\mu \to \nu_e conversion. Using data from an exposure of 3.14×10203.14\times 10^{20} protons on target, we have selected electron type events in both the near and the far detector. The near detector is used to measure the background which is extrapolated to the far detector. We have found 35 events in the signal region with a background expectation of 27±5(stat)±2(syst)27\pm 5(stat)\pm 2(syst). Using this observation we set a 90% C.L. limit of sin22θ13<0.29\sin^2 2 \theta_{13} < 0.29 for δcp=0\delta_{cp} = 0 and normal mass hierarchy. Further analysis is under way to reduce backgrounds and improve sensitivity.Comment: This was prepared for the proceedings of the XIII International Workshop on Neutrino Telescopes at the Istituto Veneto di Scienze, Lettere ed Arti in Venice, Italy held on March 10-13, 2009. The presentation was on behalf of the MINOS collaboratio

    Very Long Baseline Neutrino Oscillations, The BNL VLBNLO Concept

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    A wide energy-band neutrino beam sent over a very long baseline to a massive detector can break the degeneracies in the neutrino oscillation parameters. It can measure the disappearance parameters with precision and determine the mass hierarchy. If θ13\theta_{13} is large enough the CP violating phase can be measured with neutrino running alone and anti-neutrino running can confirm CPV and improve the parameter measurements. Brookhaven National Laboratory is pursuing such an experiment.Comment: 3 pages, 3 figures, espcrc2.sty. To be published in the proceedings of NuFact0

    A study of hydrogen environment effects on microstructure property behavior of NASA-23 alloy and related alloy systems

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    This work is part of the overall advanced main combustion chamber (AMCC) casting characterization program of the Materials and Processes Laboratory of the Marshall Space Flight Center. The influence of hydrogen on the tensile properties and ductility behavior of NASA-23 alloy were analyzed. NASA-23 and other referenced alloys in cast and hipped conditions were solution treated and aged under selected conditions and characterized using optical metallography, scanning electron microscopy, and electron microprobe analysis techniques. The yield strength of NASA-23 is not affected much by hydrogen under tensile tests carried at 5000 psig conditions; however, the ultimate strength and ductility properties are degraded. This implies that the physical mechanisms operating would be related to the plastic deformation process. The fracture surfaces characteristics of NASA-23 specimens tensile tested in hydrogen, helium, and air were also analyzed. These revealed surface cracks around specimen periphery with the fracture surface showing a combination of intergranular and transgranular modes of fracture. It is seen that the specimens charged in hydrogen seem to favor a more brittle fracture mode in comparison to air and helium charged specimens. The AMCC casting characterization program is to be analyzed for their hydrogen behavior. As a result of this program, the basic microstructural factors and fracture characteristics in some cases were analyzed