33,915 research outputs found

    Prospects for Measurement of the Neutrino Mass Hierarchy

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    The unknown neutrino mass hierarchy -- whether the ν3\nu_3 mass eigenstate is the heaviest or the lightest -- represents a major gap in our knowledge of neutrino properties. Determining the hierarchy is a critical step toward further precision measurements in the neutrino sector. The hierarchy is also central to interpreting the next generation of neutrinoless double beta decay results, plays a role in numerous cosmological and astrophysical questions, and serves as a powerful model discriminant for theories of neutrino mass generation and unification. Various current and planned experiments claim sensitivity for establishing the neutrino mass hierarchy. We review the most promising of these here, paying special attention to points of concern and consolidating the projected sensitivities into an outlook for the years ahead.Comment: Uploading final version. 13 pages, 7 figure

    Process characteristics and design methods for a 300 deg quad OP amp

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    The results of process characterization, circuit design, and reliability studies for the development of a quad OP amplifier intended for use up to 300 C are presented. A dielectrically isolated complementary vertical bipolar process was chosen to fabricate the amplifier in order to eliminate isolation leakage and the possibility of latch up. Characterization of NPN and PNP junctions showed them to be suitable for use up to 300 C. Interconnect reliability was predicted to be greater than four years mean time between failure. Parasitic MOS formation was eliminated by isolation of each device

    Library Event Matching event classification algorithm for electron neutrino interactions in the NOvA detectors

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    We describe the Library Event Matching classification algorithm implemented for use in the NOvA νμνe\nu_\mu \rightarrow \nu_e oscillation measurement. Library Event Matching, developed in a different form by the earlier MINOS experiment, is a powerful approach in which input trial events are compared to a large library of simulated events to find those that best match the input event. A key feature of the algorithm is that the comparisons are based on all the information available in the event, as opposed to higher-level derived quantities. The final event classifier is formed by examining the details of the best-matched library events. We discuss the concept, definition, optimization, and broader applications of the algorithm as implemented here. Library Event Matching is well-suited to the monolithic, segmented detectors of NOvA and thus provides a powerful technique for event discrimination.Comment: 10 pages, 7 figures. Minor fixe

    Determination of transmitter function by neuronal activity

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    The role of neuronal activity in the determination of transmitter function was studied in cultures of dissociated sympathetic neurons from newborn rat superior cervical ganglia. Cholinergic and adrenergic differentiation were assayed by incubating the cultures with radioactive choline and tyrosine and determining the rate of synthesis and accumulation of labelled acetylcholine and catecholamines. As in previous studies, pure neuronal cultures grown in control medium displayed much lower ratios of acetylcholine synthesis to catecholamine synthesis than did sister cultures grown in medium previously conditioned by incubation on appropriate nonneuronal cells (conditioned medium). However, here we report that neurons treated with the depolarizing agents elevated K+ or veratridine, or stimulated directly with electrical current, either before or during application of conditioned medium, displayed up to 300-fold lower acetylcholine/catecholamine ratios than they would have without depolarization, and thus remained primarily adrenergic. Elevated K+ and veratridine produced this effect on cholinergic differentiation without significantly altering neuronal survival. Because depolarization causes Ca2+ entry in a number of cell types, the effects of several Ca2+ agonists and antagonists were investigated. In the presence of the Ca2+ antagonists D600 or Mg2+, K+ did not prevent the induction of cholinergic properties by conditioned medium. Thus depolarization, either steady or accompanying activity, is one of the factors determining whether cultured sympathetic neurons become adrenergic or cholinergic, and this effect may be mediated by Ca2+

    Improved Measurement of Muon Antineutrino Disappearance in MINOS

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    We report an improved measurement of ν̅_μ disappearance over a distance of 735 km using the MINOS detectors and the Fermilab Main Injector neutrino beam in a ν̅_μ-enhanced configuration. From a total exposure of 2.95×10^20 protons on target, of which 42% have not been previously analyzed, we make the most precise measurement of Δm̅^2=[2.62_(-0.28)^(+0.31)(stat)±0.09(syst)]×10^(-3)  eV^2 and constrain the ν_μ mixing angle sin^(2)(2θ̅)>0.75 (90% C.L.). These values are in agreement with Δm^2 and sin^(2)(2θ) measured for νμ, removing the tension reported in [ P. Adamson et al. Phys. Rev. Lett. 107 021801 (2011)]

    Radial honeycomb core

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    Core alleviates many limitations of conventional nacelle construction methods. Radical core, made of metals or nonmetals, is fabricated either by joining nodes and then expanding, or by performing each layer and then joining nodes. Core may also be produced from ribbons or strips with joined nodes or ribbons oriented in longitudinal planes
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