1,721,035 research outputs found
Predicted CALET measurements of electron and positron spectra from 3 to 20 GeV using the geomagnetic field
No full textThe CALorimetric Electron Telescope (CALET) is an imaging calorimeter under construction for launch to the ISS in 2014 for a planned 5 year mission. CALET consists of a charge detection module (CHD) with two segmented planes of 1 cm thick plastic scintillator, an imaging calorimeter (IMC) with a total of 3 radiation lengths (X-o) of tungsten plates read out with 8 planes of interleaved scintillating fibers, and a total absorption calorimeter (TASC) with 27 X-o of lead tungstate (PWO) logs. The primary objectives of the experiment are to measure the electron e(-) + e(+) energy spectra from 1 GeV to 20 TeV, to detect gamma-rays above similar to 10 GeV, and to measure the energy spectra of nuclei from protons through iron up to 1000 TeV. In this paper we describe how the geomagnetic field at the 51.6 degrees inclination orbit of the ISS can be used to allow CALET to measure the distinct electron and positron fluxes. The positron fraction has been seen to rise above 10 GeV by previous experiments (HEAT, AMS-01), and more recently to continue to increase to higher energies (similar to 80 GeV for PAMELA, similar to 200 GeV for Fermi and similar to 350 GeV with the best statistics for AMS-02). Utilizing the geomagnetic cutoff, CALET will be able to distinguish electrons and positrons in the similar to 3-20 GeV energy range where the positron fraction turns upward to complement existing high statistics measurements. (C) 2013 COSPAR. Published by Elsevier Ltd. All rights reserved
Beam test performance of SiPM-based detectors for cosmic-ray experiments
No full textParticle detector prototypes, equipped with Silicon PhotoMultipliers (SiPMs) and readout by dedicated front-end electronics, were tested with beams of fully ionized nuclei from boron (Z=5) to nickel (Z=28) with a kinetic energy , at the Fragment Separator (FRS) of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt. The tested instruments included prototypes of Cherenkov and scintillation hodoscopes designed for cosmic-ray experiments in space or in the upper atmosphere. In this paper, we summarize the results from the analysis of the beam tests data and of dedicated laboratory tests to characterize the response of the photosensors, the front-end electronics and the performance of the prototypal detectors
Beam test performance of a pixelated silicon array for the charge identification of cosmic rays
No full textA large area silicon array for the next generation of space-based experiments has been designed to determine, via multiple dE/dx measurements, the electric charge of cosmic radiation. The instrument can achieve an excellent charge discrimination, thus allowing to assess the elemental composition of charged cosmic rays at relativistic energies. Pairs of silicon sensors segmented into pixels were tested with a beam of fully ionized nuclei from boron to nickel (Z=28) with a kinetic energy of , at the Fragment Separator (FRS) of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt. The response of the sensors to different nuclear species was accurately characterized. The results of the beam test clearly show that a double-layered silicon array can achieve single-element separation with a resolution close to 0.2 electron charge units, in the whole interval of atomic number Z under test
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
The CREAM balloon experiment
No full textCREAM (Cosmic Ray Energetic and Mass) is an experiment aiming at the
measurement of the composition of the cosmic ray nuclei from proton to iron, in an energy
range between ' 1011 and ' 1015 eV, by exploiting the Ultra Long Duration Balloon
(ULDB) flights technology. Goal of the experiment is to give new insights in the origin,
propagation and acceleration of the Galactic cosmic rays. A first balloon flight took place
in December 2004- January 2005 in Antarctica, for a total of more than 42 days
Variations on the Author
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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