66 research outputs found

    Search for non-relativistic Magnetic Monopoles with IceCube

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    The IceCube Neutrino Observatory is a large Cherenkov detector instrumenting 1km31\,\mathrm{km}^3 of Antarctic ice. The detector can be used to search for signatures of particle physics beyond the Standard Model. Here, we describe the search for non-relativistic, magnetic monopoles as remnants of the GUT (Grand Unified Theory) era shortly after the Big Bang. These monopoles may catalyze the decay of nucleons via the Rubakov-Callan effect with a cross section suggested to be in the range of 1027cm210^{-27}\,\mathrm{cm^2} to 1021cm210^{-21}\,\mathrm{cm^2}. In IceCube, the Cherenkov light from nucleon decays along the monopole trajectory would produce a characteristic hit pattern. This paper presents the results of an analysis of first data taken from May 2011 until May 2012 with a dedicated slow-particle trigger for DeepCore, a subdetector of IceCube. A second analysis provides better sensitivity for the brightest non-relativistic monopoles using data taken from May 2009 until May 2010. In both analyses no monopole signal was observed. For catalysis cross sections of 1022(1024)cm210^{-22}\,(10^{-24})\,\mathrm{cm^2} the flux of non-relativistic GUT monopoles is constrained up to a level of Φ901018(1017)cm2s1sr1\Phi_{90} \le 10^{-18}\,(10^{-17})\,\mathrm{cm^{-2}s^{-1}sr^{-1}} at a 90% confidence level, which is three orders of magnitude below the Parker bound. The limits assume a dominant decay of the proton into a positron and a neutral pion. These results improve the current best experimental limits by one to two orders of magnitude, for a wide range of assumed speeds and catalysis cross sections.Comment: 20 pages, 20 figure

    Searches for Extended and Point-like Neutrino Sources with Four Years of IceCube Data

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    We present results on searches for point-like sources of neutrinos using four years of IceCube data, including the first year of data from the completed 86-string detector. The total livetime of the combined dataset is 1,373 days. For an E2^{-2} spectrum the median sensitivity at 90\% C.L. is 1012\sim 10^{-12} TeV1^{-1}cm2^{-2}s1^{-1} for energies between 1 TeV-1 PeV in the northern sky and 1011\sim 10^{-11} TeV1^{-1}cm2^{-2}s1^{-1} for energies between 100 TeV - 100 PeV in the southern sky. The sensitivity has improved from both the additional year of data and the introduction of improved reconstructions compared to previous publications. In addition, we present the first results from an all-sky search for extended sources of neutrinos. We update results of searches for neutrino emission from stacked catalogs of sources, and test five new catalogs; two of Galactic supernova remnants and three of active galactic nuclei. In all cases, the data are compatible with the background-only hypothesis, and upper limits on the flux of muon neutrinos are reported for the sources considered.Comment: 36 pages, 15 figures. Submitted to the Astrophysical Journa

    Planck 2015 results. XVI. Isotropy and statistics of the CMB

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    We test the statistical isotropy and Gaussianity of the cosmic microwave background (CMB) anisotropies using observations made by the Planck satellite. Our results are based mainly on the full Planck mission for temperature, but also include some polarization measurements. In particular, we consider the CMB anisotropy maps derived from the multi-frequency Planck data by several component-separation methods. For the temperature anisotropies, we find excellent agreement between results based on these sky maps over both a very large fraction of the sky and a broad range of angular scales, establishing that potential foreground residuals do not affect our studies. Tests of skewness, kurtosis, multi-normality, N-point functions, and Minkowski functionals indicate consistency with Gaussianity, while a power deficit at large angular scales is manifested in several ways, for example low map variance. The results of a peak statistics analysis are consistent with the expectations of a Gaussian random field. The “Cold Spot” is detected with several methods, including map kurtosis, peak statistics, and mean temperature profile. We thoroughly probe the large-scale dipolar power asymmetry, detecting it with several independent tests, and address the subject of a posteriori correction. Tests of directionality suggest the presence of angular clustering from large to small scales, but at a significance that is dependent on the details of the approach. We perform the first examination of polarization data, finding the morphology of stacked peaks to be consistent with the expectations of statistically isotropic simulations. Where they overlap, these results are consistent with the Planck 2013 analysis based on the nominal mission data and provide our most thorough view of the statistics of the CMB fluctuations to date

    Planck 2013 results. III. LFI systematic uncertainties

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    We present the current estimate of instrumental and systematic effect uncertainties for the Planck-Low Frequency Instrument relevant to the first release of the Planck cosmological results. We give an overview of the main effects and of the tools and methods applied to assess residuals in maps and power spectra. We also present an overall budget of known systematic effect uncertainties, which are dominated sidelobe straylight pick-up and imperfect calibration. However, even these two effects are at least two orders of magnitude weaker than the cosmic microwave background (CMB) fluctuations as measured in terms of the angular temperature power spectrum. A residual signal above the noise level is present in the multipole range <20\ell<20, most notably at 30 GHz, and is likely caused by residual Galactic straylight contamination. Current analysis aims to further reduce the level of spurious signals in the data and to improve the systematic effects modelling, in particular with respect to straylight and calibration uncertainties.Comment: Accepted for publication by A&

    Multimessenger Search for Sources of Gravitational Waves and High-Energy Neutrinos: Results for Initial LIGO-Virgo and IceCube

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    We report the results of a multimessenger search for coincident signals from the LIGO and Virgo gravitational-wave observatories and the partially completed IceCube high-energy neutrino detector, including periods of joint operation between 2007-2010. These include parts of the 2005-2007 run and the 2009-2010 run for LIGO-Virgo, and IceCube's observation periods with 22, 59 and 79 strings. We find no significant coincident events, and use the search results to derive upper limits on the rate of joint sources for a range of source emission parameters. For the optimistic assumption of gravitational-wave emission energy of 10210^{-2}\,M_\odotc2^2 at 150\sim 150\,Hz with 60\sim 60\,ms duration, and high-energy neutrino emission of 105110^{51}\,erg comparable to the isotropic gamma-ray energy of gamma-ray bursts, we limit the source rate below 1.6×1021.6 \times 10^{-2}\,Mpc3^{-3}yr1^{-1}. We also examine how combining information from gravitational waves and neutrinos will aid discovery in the advanced gravitational-wave detector era

    Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

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    Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

    Observation of High-Energy Astrophysical Neutrinos in Three Years of IceCube Data

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    Comportamiento productivo, consumo de nutrientes y productividad al parto de ovejas de pelo suplementadas con energía en el preparto durante verano e invierno

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    Se utilizaron 48 ovejas multíparas gestantes para evaluar el efecto de la suplementación energética (100 y 125% de energía metabolizable) y la época (verano e invierno) sobre el comportamiento productivo y el consumo de nutrientes durante el último tercio de gestación, en un clima árido. Adicionalmente fue evaluada la productividad de la oveja al parto. Las dietas experimentales se ofrecieron del día 100 de gestación al parto. Las condiciones climáticas en verano fueron de estrés calórico y en invierno termoneutrales. La interacción suplementación por época no fue significativa (P > 0,05) para ninguna variable. Las ovejas suplementadas comparadas con el grupo testigo presentaron mayor (P < 0,05) consumo de nutrientes digestibles totales y energía metabolizable, asimismo, mayor (P < 0,05) ganancia diaria de peso y eficiencia alimentaria. La suplementación no afectó (P > 0,05) el peso al nacimiento de los corderos y la productividad de la oveja al parto. Por lo demás, el consumo de nutrientes, la ganancia de peso y la eficiencia alimentaria fueron mayores (P < 0,05) en invierno que en verano. Al parto, la época no afectó (P > 0,05) el peso al nacimiento pero sí (P < 0,05) el tamaño y peso de camada. En conclusión, la suplementación energética mejoró el consumo de energía, lo que se reflejó en un incremento en el peso vivo de la oveja pero no sobre el peso al nacimiento de las crías. Las altas temperaturas de verano redujeron la productividad de la oveja como resultado de un bajo consumo de nutrientes
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