1,721,219 research outputs found
The analysis of hybrid events in the Pierre Auger Observatory
No full textThe Pierre Auger Observatory detects ultra-high energy cosmic rays by implementing two complementary air-shower measurements. The combination of the single tank information from the surface detector (SD) and the calorimetric measurements of the shower profile using the fluorescence detector (FD), known as the "hybrid" technique, provides a more reliable event reconstruction than using either detector alone. In this paper the approach used to evaluate the cosmic ray flux using this class of events is described. The analysis method is discussed considering its main steps: the event selection, the detector up time evaluation and the exposure calculation. © 2008 Elsevier B.V. All rights reserved
Exposure of the hybrid detector of the Pierre Auger Observatory
No full textThe exposure of the Pierre Auger Observatory for events observed by the fluorescence detector in coincidence with at least one station of the surface detector is calculated. All relevant monitoring data collected during the operation, like the status of the detector, background light and atmospheric conditions are considered in both simulation and reconstruction. This allows to realistically reproduce time dependent data taking conditions and efficiencies
Update on the measurement of the CR energy spectrum above 1018 eV made using the pierre auger observatory
No full textThe flux of cosmic rays above 1018 eV has been measured with unprecedented precision at the Pierre Auger Observatory. Two analysis techniques have been used to extend the spectrum downwards from 3 × 1018 eV, with the lower energies being explored using a unique technique that exploits the hybrid strengths of the instrument. The spectral features are presented in detail and the impact of systematic uncertainties on these features is addressed. The increased exposure of about 60% with respect to previous publications is exploited
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Multi-Messenger Physics With the Pierre Auger Observatory
No full textAn overview of the multi-messenger capabilities of the Pierre Auger Observatory is presented. The techniques and performance of searching for Ultra-High Energy neutrinos, photons and neutrons are described. Some of the most relevant results are reviewed, such as stringent upper bounds that were placed to a flux of diffuse cosmogenic neutrinos and photons, bounds placed on neutrinos emitted from compact binary mergers that were detected by LIGO and Virgo during their first and second observing runs, as well as searches for high energy photons and neutrons from the Galactic center that constrain the properties of the putative Galactic PeVatron, observed by the H.E.S.S. collaboration. The observation of directional correlations between ultra-high energy cosmic rays and either high energy astrophysical neutrinos or specific source populations, weighted by their electromagnetic radiation, are also discussed. They constitute additional multi-messenger approaches aimed at identifying the sources of high energy cosmic rays
Detection of GRB signals with fluorescence detectors
No full textGamma ray bursts are being searched in many ground based experiments detecting the high energy component (GeV-TeV energy range) of the photon bursts. In this paper, fluorescence detectors are considered as possible candidate devices for these searches. It is shown that GRB photons induce fluorescence emission of UV photons on a wide range of their spectrum. The induced fluorescence flux is dominated by GRB photons from 0.1 to about 100 MeV and, once the extinction through the atmosphere is taken into account, it is distributed over a wide angular region. This flux can be detected through a monitor of the diffuse photon flux, provided that its maximum value exceeds a threshold value, that is primarily determined by the sky brightness above the detector. The feasibility of this search and the expected rates are discussed on the basis of the current GRB observations. The basic requirements for fluorescence detectors to search for GRB signals are finally discussed. It is shown that these requirements are only partially fulfilled by the existing fluorescence detectors and therefore their GRB detection capability turns out to be marginal. (C) 2008 Elsevier B.V. All rights reserved
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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