404 research outputs found
Mediarecht en communicatievrijheid : situering van het mediarecht als rechtsgebied en van de communicatievrijheid als grondslag van het mediarecht : adstructie van de communicatievrijheid op basis van art. 10 E.V.R.M
No full textThe scientific legacy of J. P. Elliott
No full text14 pagesJames Philip Elliott, one of the towering figures of nuclear physics of the second half of the twentieth century, died on the 21st of October 2008. Obituaries appeared in the British press but relatively little attention was paid by the international scientific community to Elliott's contributions. Given their importance, in particular for theoretical nuclear physics, it seems appropriate to reflect here, two years after his death, on the scientific legacy left by Phil Elliott
Geometry of shell-model matrix elements
No full textWith use of Wigner’s classical-limit expressions for 3 j symbols, matrix elements of the nuclear shell model are given a geometric interpretation in terms of the angle between neutron and proton angular momenta
A geometry for the shell model
No full textInternational audienceA geometric interpretation is given of matrix elements of a short-range interaction between states that are written in terms of aligned neutron–proton pairs
Nuclear charge radii and electric monopole transitions in the interacting boson model
No full text8 pages, 5 figures, to be published in AIP Conference Proceedings, Proceedings of the International Conference on Beauty in Physics: Theory and Experiment, Cocoyoc, Mexico, May 12-18, 2012International audienceThe interacting boson model (IBM) of Arima and Iachello is applied to calculate nuclear charge radii and electric monopole transitions of even-even nuclei in the rare-earth region. Consistent operators are used for the two observables. A relation between summed M1 strength and values is pointed out
Interacting boson models for N~Z nuclei
No full textInternational audienceThis contribution discusses the use of boson models in the description of N~Z nuclei. A brief review is given of earlier attempts, initiated by Elliott and co-workers, to extend the interacting boson model of Arima and Iachello by the inclusion of neutron-proton s and d bosons with T = 1 (IBM-3) as well as T = 0 (IBM-4). It is argued that for the N~Z nuclei that are currently studied experimentally, a different approach is needed which invokes aligned neutron-proton pairs with angular momentum J = 2j and isospin T = 0. This claim is supported by an analysis of shell-model wave functions in terms of pair states. Results of this alternative version of the interacting boson model are compared with shell-model calculations in the 1g9/2 shell
Seniority isomers in nuclei
No full textInternational audienceSeniority isomers are nuclear states with an electromagnetic decay that is hindered by selection rules related to the seniority quantum number. A simple analysis is presented of their possible formation with reference to the nickel isotopes 70−76Ni and the N = 50 isotones from molybdenum to cadmium. It is shown that the existence of seniority isomers in a j = 9/2 shell is predominantly governed by the quadrupole pairing matrix element of the nucleon-nucleon interaction. The analysis is generalized to shells with larger j
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