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Progress in the study of the gamma decay of the giant dipole resonance in very hot rotating nuclei
No full textThe γ decay of the Giant Dipole Resonance in 132Ce nuclei has been measured in the compound temperature range 2.5 - 4.1 MeV using a symmetric reaction 64Ni (300, 400, 500 MeV) + 68Zn and an asymmetric one 16O (130, 250 MeV) + 116Sn. Both cases produce 132Ce compound nuclei at the same excitation energy and angular momentum. Light charged particles and evaporation residues have been measured in coincidence with high energy γ-rays. The data show that pre-equilibrium emission is present only in the asymmetric reaction while only statistical emission from a fully equilibrated 132Ce compound is present in the symmetric one. The measured Giant Dipole Resonance widths show an almost linear increase with the effective temperature. Such a measured trend is reproduced by the thermal fluctuation model which includes the lifetime of the compound nucleus. The comparison between the high energy γ-ray spectra in the symmetric and asymmetric reactions shows a dynamic dipole emission in the 16O-induced reaction. The yield is consistent with what has been previously measured in the same mass and energy range
The gamma decay of the giant dipole resonance : From zero to finite temperature
No full textThis paper is intended to give a selected and rather brief overview of the work made in the last thirty years to study the properties of the giant dipole resonance focusing in particular on nuclei formed at finite temperatures using heavy ion reactions. The physical problems that are discussed (using examples of particular results) in this paper can be grouped into 3 major topics: (i) the temperature dependence of the GDR width; (ii) the dipole oscillation in reaction dynamics; (iii) the isospin mixing at finite temperature
Progress in the study of the gamma-decay of the giant dipole resonance in hot nuclei
No full textThe problem of the damping of the Giant Dipole Resonance (GDR) at finite temperature at T>2 MeV is discussed here. The experimental results are based on fusion evaporation reactions. The most recent results on the mass region A = 132 (Ce isotopes) obtained in exclusive measurements are compared with the existing results on the A = 110–120 region (Sn isotopes). The comparison with the theoretical predictions based on thermal shape fluctuations is also discussed. The GDR width is found to increase also in the region T>2 MeV and this is accounted by the combined effect of the increase of the compound nucleus width (smaller lifetime) and to the increase of the average deformation of the nucleus
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
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