3,813 research outputs found

    The SuperNova Early Warning System

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    A core collapse in the Milky Way will produce an enormous burst of neutrinos in detectors world-wide. Such a burst has the potential to provide an early warning of a supernova's appearance. I will describe the nature of the signal, the sensitivity of current detectors, and SNEWS, the SuperNova Early Warning System, a network designed to alert astronomers as soon as possible after the detected neutrino signal.Comment: 3 pages, appearing in refereed proceedings of "Hotwiring the Transient Universe 2007", eds. A. Allan, J. S. Bloom, R. Seaman, Astron. Nachr. vol. 329, March 200

    MONOLITH: a next generation experiment for athospheric neutrinos

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    MONOLITH is a massive magnetized tracking calorimeter, optimized for the detection of atmospheric muon neutrinos, proposed at the Gran Sasso laboratory in Italy. The main goal is to establish (or reject) the neutrino oscillation hypothesis through an explicit observation of the full first oscillation swing (the ``L/E pattern''). Its performance, status and prospects are briefly reviewed.Comment: Talk given at Europhysics Neutrino Oscillation Workshop (NOW2000), Otranto, Italy, September 9-16, 2000 (4 pages, 3 figures

    Detector Time Offset and Off-line Calibration in EAS Experiments

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    In Extensive Air Shower (EAS) experiments, the primary direction is reconstructed by the space-time pattern of secondary particles. Thus the equalization of the transit time of signals coming from different parts of the detector is crucial in order to get the best angular resolution and pointing accuracy allowed by the detector. In this paper an off-line calibration method is proposed and studied by means of proper simulations. It allows to calibrate the array repeatedly just using the collected data without disturbing the standard acquisition. The calibration method is based on the definition of a Characteristic Plane introduced to analyze the effects of the time systematic offsets, such as the quasi-sinusoidal modulation on azimuth angle distribution. This calibration procedure works also when a pre-modulation on the primary azimuthal distribution is present.Comment: 9 pages, 5 figures, submitted to Astroparticle Physic

    Spectra of hadrons and muons in the atmosphere: primary spectra, characteristics of hadron-air interactions

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    Self-consistency of interaction models QGSJET 01, SIBYLL 2.1, NEXUS 3.97 and QGSJET II is checked in terms of their ability to reproduce simultaneously experimental data on fluxes of muons and hadrons. From this point of view SIBYLL 2.1 gives the most acceptable, though not quite satisfactory, results. Analysis of the situation for muons supports our previous conclusions, that high-energy muon deficit is due both to underestimation of primary light nuclei fluxes in direct emulsion chamber experiments and to softness of p+A→π±,K±+Xp+A\to\pi^\pm,K^\pm+X inclusive spectra in fragmentation region, especially prominent in case of QGSJET 01 model.Comment: Talk given at the XIVth ISVHECRI (Weihai, China, 2006

    The Crux of the Matter: Ratings and Credit Risk Valuation at the heart of the Structured Finance Crisis

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    The 2007/2008 global credit crisis was born out of opaque securitization transactions. Introducing structured products risk estimation techniques shows how the most basic investment analysis could not be done without detailed and updated knowledge on the assets of the pool. Access to such details was crucial for investors to perform an autonomous valuation, the lack of which led to a pervading acceptance of ratings at face value. The crisis brought numerous delusions to naĂŻve users of these privately issued opinions. Coming back to the central role that investor played during the previous speculative episode and introducing a theoretical discussion on the dynamics of market finance, it is shown that trusting market discipline and due diligence was bound to end up being misguiding. Given that unprecedented rating volatility brought a share of the blame game to rating firms, strategies that would aim at securing an informed use of ratings are finally outlined.financial crisis, credit risk, rating agencies

    Muon simulation codes MUSIC and MUSUN for underground physics

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    The paper describes two Monte Carlo codes dedicated to muon simulations: MUSIC (MUon SImulation Code) and MUSUN (MUon Simulations UNderground). MUSIC is a package for muon transport through matter. It is particularly useful for propagating muons through large thickness of rock or water, for instance from the surface down to underground/underwater laboratory. MUSUN is designed to use the results of muon transport through rock/water to generate muons in or around underground laboratory taking into account their energy spectrum and angular distribution.Comment: 22 pages, 9 figures, 1 table, to be published in Computer Physics Communication

    Cosmic rays measurements around the knee of the primary spectrum

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    In this contribution I will summarize and discuss some recent results about the study of the knee of the cosmic rays energy spectrum, indicating that this spectral feature is originated by astrophysical processes. I will then discuss the current experimental efforts that are giving further insights. Latest all particle spectrum measurements have shown that, between 1016eV and 1018eV, the spectrum cannot be described by a single slope power law: an hardening around 1016eV and a steepeningaround 1017eV have been observed. This last feature has been attributed, by the KASCADE-Grande experiment, to the heavy primary component, confirming that the energy of the elemental spectra change of slope increase with the mass of the primary particle
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