1,721,020 research outputs found
Design and development of the target-ion source system for the SPES project
Get PDFThe most important project of LNL (National Laboratory of Legnaro), one of the four Laboratory of INFN (National Institute for Nuclear Physics), is the SPES project, now at the construction phase. The aim of this new facility is to produce Radioactive Ion Beams in the neutron rich side of the so-called “valley of stability”. This is a very challenging project since it requires a lot of knowledge and studies from physical, chemical, engineering points of view. The core of the facility is a uranium carbide target mantained at high temperature (above 2000°C) which produces by fission radioactive atoms by means of an energetic and powerful proton beam.
In this thesis, both the target and some of the most delicate devices which have to be installed inside the SPES bunker where the nuclear reactions occur are presented. In particular, the design phase of the target and the tests performed at iThemba LABS in South Africa will be presented, as the design of all the diagnostics that have to be installed to safely manage and control the production of the radioactive beams. Finally, the design phases and tests of the Wien Filter used as the preliminary mass separator to decrease the unwanted radioactivity along the beam line will be showed
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
A combined experimental and numerical approach for the control and monitoring of the SPES target during operation at high temperature
No full textThe SPES project at INFN-LNL aims at the production of neutron-rich Radioactive Ion Beams (RIBs) using
the ISOL (Isotope Separation On Line) technique. A 40 MeV 200 lA proton beam will directly impinge a
uranium carbide target, generating approximately 1013 fissions per second. The target system is installed
under vacuum inside a water-cooled chamber, and have to maintain high working temperatures, close to
2000 C. During operation the proton beam provides the heating power required to keep the target at the
desired temperature level. As a consequence, its characteristics have to be strictly controlled in order to
avoid undesired overheating. According to the original design of the control system, the proton beam can
be suddenly interrupted in case of out of range vacuum or cooling water flow levels. With the aim to
improve the reliability of the control system a set of temperature sensors has been installed close to
the target. Their types and installation positions were defined taking into consideration the detailed
information coming from a dedicated thermal–electric model that allowed to investigate the most critical
and inaccessible target hot-spots.
This work is focused on the definition and experimental validation of the aforementioned numerical
model. Its results were used to appropriately install two type C thermocouples, a PT100 thermoresistance
and a residual primary beam current detector. In addition the numerical model will be used
for the definition of appropriate thresholds for each installed temperature sensor, since it allows to define
a relationship between the locally measured values with the overall calculated temperature field. In case
of over temperatures the monitoring system will send warning signals or in case interrupt the proton
beam
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
Study of a simplified CoolGal target to support the Phase-0 NEPIR facility
No full textThe NEPIR facility (NEutron and Proton Irradiation), currently in development at the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nucleare (LNL-INFN), will serve as the first fast neutron (En > 1 MeV) irradiation source in Italy specifically designed to support advanced scientific research and industrial applications. Powered by the SPES (Selective Production of Exotic Species) variable-energy proton cyclotron, NEPIR will be implemented in two main phases. Phase-0 will deliver continuous (white spectrum) and Pseudo Quasi-Monoenergetic neutron fields, while Phase-1 will introduce true Quasi-Monoenergetic Neutron beams and an atmospheric-like neutron spectrum. The Phase-0 target system, CoolGal, is based on a thick beryllium target and is intended to evolve into a galinstan-cooled configuration for high-power operation. To simplify initial commissioning, a water-cooled prototype—excluding galinstan—has been developed. This paper presents thermal and structural analysis of the prototype and evaluates its neutron production performance through Monte Carlo simulations. The primary goal is to support an experiment to measure the double-differential neutron yield of the Be(p,n) reaction in the 30–70 MeV range. These results will provide new experimental data to supplement current JENDL evaluations and guide the development of advanced neutron sources at NEPIR
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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