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Results from CERN experiment WA80
No full textRecent photon-measurement results are presented. Accurate reconstructed and {pi}{sup 0} and {eta} results have been obtained down to signal/noise ratios of 0.002. The production of {eta} mesons was found to be consistent with MT scaling observed in hadron-hadron collisions. ``Direct,`` single-photon yields were extracted from high-statistics S+Au data obtained at 200 GeV/nucleon. A slight excess of photons over the number of photons that can be accounted for by hadronic decays was observed for central events. Two-proton correlations were obtained in the target fragmentation region in p+A, {sup 16}O+A and {sup 32}S+A reaction at 200 GeV/nucleon. Source radii extracted from the correlations were found to follow an A{sup 1/3} dependence. This indicates that entire target nuclei are involved in the collisions and that a simple target-spectator picture does not apply at these energies
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Investigation of direct photon production in 200 A GeV S + Au reactions
No full textDirect thermal photons in the p{sub T} range of 0--5 GeV/c are expected to provide a sensitive probe of the early conditions of the Quark Gluon Plasma which may be formed in relativistic heavy ion collisions. The production of single photons in 200 A GeV S + Au reactions has been investigated using the 3,800 element Pbglass calorimeter of CERN experiment WA80. Neutral {pi}{sup 0} and {eta} cross sections have been measured via their two-photon decay branch yields. The measured {pi}{sup 0} and {eta} cross sections have been used to calculate the expected inclusive yield of decay photons. Excess photon yield, beyond that attributed to radiative decays and background sources, may be associated with thermal photon emission. Excess, ``direct`` photon yields have been extracted from high-statistics S + Au photon data for different event centrality classes. A slight excess photon yield above that which may be accounted for by hadronic decays was observed for central events
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Nuclear stopping power
Get PDFEstimators of the stopping power and the attainable energy density in high energy p+A and A+A collisions are discussed. Scaling laws for the stopping power and the energy densities are derived based on a phenomenological parameterization of transverse energy data from the WA80 collaborations at CERN. The shortcomings of the widely used Bjorken formula are discussed
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
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
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Neutral pion production in nucleus-nucleus collisions at 158 and 200 GeV/nucleon
Get PDFTwo years ago, at the 12th Winter Workshop on Nuclear Dynamics held here in Snowbird, the authors presented WA80 limits on direct photon production in 200-GeV {sup 32}S + Au collisions. It was found that the results were consistent (within 1{sigma}) with the absence of an excess of photons over those that can be accounted for by the two-photon decay branches of {pi}{sup 0} and {eta} mesons and by the small photon contributions from other radiative decays. They are in the process of finalizing the direct-photon production results from collisions of lead nuclei at 158 GeV/nucleon. The author briefly discusses the status of the analysis and gives some preliminary results at the end of this talk. However, most of this presentation is concerned with a very different aspect of the photon measurements: distributions of neutral pions. In contrast to direct photons which probe initial collision conditions, hadrons, such as neutral pions, interact strongly and decouple late in the reaction evolution and, thus, provide information concerning the system at freeze out. Transverse momentum spectra at low and intermediate p{sub T} relate to thermodynamic and hydrodynamic descriptions of the hot, dense systems. In addition, the high-p{sub T} region reflects the hard-scattering regime and may help one understand initial-state particle production by forming a bridge to proton-proton and proton-nucleus results. It follows that it is essential that the {pi}{sup 0} measurements cover a large p{sub T} range
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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