1,720,988 research outputs found
The calibration system for the Borexino experiment
No full textBorexino is a large liquid scintillator detector designed to study solar neutrinos in real-time. Since the beginning of data-taking in 2007, Borexino has been able to perform a complete spectroscopy of neutrinos from the Sun, thanks to its unprecedented radiopurity. Calibrations have been crucial for the success of the experiment. In this paper, we describe the Borexino calibration system, emphasizing its most critical aspects, in particular to those related to radiopurity. We also discuss some of the results of the calibration campaigns performed in Borexino Phase-1
Geo-neutrinos signal with Borexino
Full text linkGeo-neutrinos are electron antineutrinos produced in β-decays of long-lived radioactive isotopes naturally present in the Earth (238U, 232Th and 40K).
By measuring their fluxes it is possible to have a unique direct probe of our planet’s
interior, to reveal the terrestrial distribution of uranium and thorium and to assess the radiogenic contribution to the total heat balance of the Earth. The Borexino
experiment is one of the few which can perform a geo-neutrino analysis: we present
the evidence of geo-neutrinos’ signal with 252.6 ton·y Borexino data
Calibration of the solar neutrino detectors
No full textCalibrations have been crucial for the success of solar neutrino experiments. In this contribution we review the calibration strategies adopted by different solar neutrino experiments. In particular, we will emphasize their common critical aspects and their main differences. In order to do so, we will schematically divide the solar neutrino experiments in two groups: those based on radiochemical techniques, i.e. Homestake, Gallex/GNO, SAGE and those based on real-time techniques i.e. Kamiokande, Super-Kamiokande, SNO, Borexino and KamLAND
THE BOREXINO IMPACT IN THE GLOBAL ANALYSIS OF NEUTRINO DATA
No full textThis thesis reports on work I carried out within the Borexino collaboration in the past three years. The main purpose of my work was to collect, analyze and understand the implications of the Borexino results in neutrino oscillation physics and in solar physics. We first studied the impact of each single piece of information coming from the
Borexino experiment in determining the allowed regions of the (tan(theta_12), D m2_21) space of parameters. Concerning the neutrino oscillations field, we combined the Borexino results with those obtained by the other solar experiment (Gallex/GNO, SAGE, Homestake, Super
Kamiokande, SNO) and we showed that, thanks to the Borexino inclusion, the LOW region of MSW regime is, for the first time, strongly disfavored by solar neutrino data alone.
For what concerns solar Physics, in order to study the Standard Solar Model parameters and to look deeper into the low/high metallicity controversy, we left Phi(7Be) and Phi(8B) as free parameters of the fit. Under the luminosity constraint, we showed how, at present, solar neutrino data cannot discriminate between the low/high metallicity hypothesis in the standard solar model
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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