1,721,292 research outputs found
Fission Fragment Production from Uranium Carbide Disc Targets
No full textA possible solution for a target system aimed at the production of exotic nuclei as a result of high-energy fissions in 238U compounds has been analyzed. The configuration proposed is constituted by a primary proton team (40 MeV, 0.4 mA) directly impinging on a UC2 multiple-disc target inserted within a cylindrical tungsten box. In order to extract the fission fragments, the tungsten box has to be kept at 2000°C. This system has been conceived to obtain both a high number of fission fragments (about 2 . 1013 atoms/s) and a quite low power deposition in the target. The power release and the fragment distribution have been calculated by means of the Monte Carlo code MCNPX. The thermal analysis of the proposed configuration shows the capability of the thermal radiation to cool the discs with a reasonable margin below the material melting point. Moreover, the possibility of increasing such margin with simple modifications of the target design is shown by means of parametric analyses. The thermal analysis of the tungsten box, also cooled by radiation, points out the necessity to heat it and/or shield it thermally, in order to take it at the requested temperature. Preliminary calculations of the target-induced activity have also been performed
Graphene derived lanthanum carbide targets for the SPES ISOL facility
Full text linkGraphene derived lanthanum carbide targets for the SPES ISOL facility By:Corradetti, S (Corradetti, S.)[ 1 ] ; Carturan, SM (Carturan, S. M.)[ 1,2 ] ; Andrighetto, A (Andrighetto, A.)[ 1 ] ; Mariotto, G (Mariotto, G.)[ 3 ] ; Giarola, M (Giarola, M.)[ 3 ] ; Fabrizi, A (Fabrizi, A.)[ 4 ] ; Maddalena, A (Maddalena, A.)[ 5 ] ; Biasetto, L (Biasetto, L.)[ 1,4 ] CERAMICS INTERNATIONAL Volume: 43 Issue: 14 Pages: 10824-10831 DOI: 10.1016/j.ceramint.2017.05.106 Published: OCT 1 2017 View Journal Impact Abstract Lanthanum carbide based targets were produced as benchmark tests before the production of radioactive uranium carbide targets. Carbides possessing excess carbon and porosity seem to be the best candidates as target for the production of exotic beams in the SPES-ISOL facility. In addition, the capability of tailoring properties such as grains size and pores size represents a step ahead to improve the ions release efficiency. In this work, multilayered graphene was used as source of carbon for the production of LaC and the main physical properties of the produced targets were compared to standard LaCx produced using micrometric graphite. The main output of the work consisted in the reduced total porosity (28.8 vol% vs 47.8 vol%) and increased shrinkage (20.4 vol% vs 5.8 vol%) of the LaCx-Graphene samples compared to LaCx-Graphite ones. This result showed how graphene can be successfully employed as sintering aid for the sintering of carbides. Further studies are ongoing with UO2 as starting reagent for carburization within the project AUL-2013-16-176 "Study of the use of graphene as source of carbon for Uranium Carbide-Graphene nanocomposites production" now under conclusion at the European Commission DG Joint Research Centre - JRC
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
The SPES Direct Target Project at LNL
No full textThe SPES Direct Target Project at the Laboratori Nazionali di Legnaro (Italy), devoted to the construction of a Radioactive Ion Beam (RIB) Facility within the framework of the new European RIB panorama, is presented. An innovative configuration for the SPES Project, for the production of neutron-rich exotic nuclei, proposes the use of a primary proton beam (40 MeV, 0.2 mA), directly impinging on a large Multi-Slice Uranium Carbide Direct Target. The goal is to reach a high number of fission products (up to 1013 fissions/s), still keeping a quite low power deposition inside the target. The description of the overall facility together with details on the Direct Target configuration is presented. Thermo-mechanical calculations, material preparation and characterisation, effusion--diffusion model predictions for the estimation of the release time and total release fraction for different life times and isotopes will be discussed. Finally, a scaled (1:5) prototype of the Target System built to be tested and compared under existing proton beam facilities, will be described
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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