1,721,075 research outputs found
A novel experimental approach to characterize neutron fields at high- and low-energy particle accelerators.
Full text linkThe characterization of particle accelerator induced neutron fields is challenging but fundamental for research and industrial activities, including radiation protection, neutron metrology, developments of neutron detectors for nuclear and high-energy physics, decommissioning of nuclear facilities, and studies of neutron damage on materials and electronic components. This work reports on the study of a novel approach to the experimental characterization of neutron spectra at two complex accelerator environments, namely the CERF, a high-energy mixed reference field at CERN in Geneva, and the Bern medical cyclotron laboratory, a facility used for multi-disciplinary research activities, and for commercial radioisotope production for nuclear medicine. Measurements were performed through an innovative active neutron spectrometer called DIAMON, a device developed to provide in real time neutron energy spectra without the need of guess distributions. The intercomparison of DIAMON measurements with reference data, Monte Carlo simulations, and with the well-established neutron monitor Berthold LB 6411, has been found to be highly satisfactory in all conditions. It was demonstrated that DIAMON is an almost unique device able to characterize neutron fields induced by hadrons at 120 GeV/c as well as by protons at 18 MeV colliding with different materials. The accurate measurement of neutron spectra at medical cyclotrons during routine radionuclide production for nuclear medicine applications is of paramount importance for the facility decommissioning. The findings of this work are the basis for establishing a methodology for producing controlled proton-induced neutron beams with medical cyclotrons
DISPOSITIVO PER IL RILEVAMENTO DI UNA RADIAZIONE IONIZZANTE
No full textDispositivo (1) per il rilevamento di una radiazione ionizzante, il dispositivo (1) comprendendo: un corpo principale (2) dotato di una cavità interna (3) avente simmetria assiale attorno ad un asse centrale (100); una pluralità di elementi di rilevamento (4) strutturati per essere posti ad una rispettiva differenza di tensione elettrica rispetto al detto corpo principale (2) per generare un rispettivo segnale di carica (CS) rappresentativo di una quantità di carica elettrica raccolta dall’elemento di rilevamento (4), dove gli elementi di rilevamento (4) sono disposti internamente alla cavità interna (3) tra loro spazialmente separati e in sequenza spaziale lungo l’asse centrale (100), e dove ciascun elemento di rilevamento (4) ha simmetria assiale attorno a detto asse centrale (100).
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Analytical model for a monolithic silicon telescope - Response function of the E stage
No full textA monolithic silicon telescope coupled to a polyethylene radiator was studied and tested as a neutron
spectrometer. The detector consists of a DE and an E stage detector, about 1.9 and 500 mm in thickness,
respectively. The neutron spectra were derived from the measurement of the energy deposited in the E
stage by recoil-protons generated in the radiator. The detectable energy range of the present detection
system is about 0.350–8 MeV. In order to optimize the reconstruction of the impinging neutron spectra,
an analytical model of the response functions of the detection system to mono-energetic neutrons was
developed and implemented in an unfolding procedure. The model is based on the kinematics of neutron
elastic scattering on hydrogen and takes into account the actual geometrical structure of the silicon
telescope. The calculated response functions were compared with the results of Monte Carlo simulations
(by using the FLUKA code) and those obtained by an experimental characterization
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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