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Séminaire présenté par le Professeur W. Von OERTZEN

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Nuclear Clusters and Molecules
Nuclear structure beyond the shell model.

Professeur W. Von OERTZEN
(Hahn Meitner Institut Berlin and Freie Universität Berlin)

le Jeudi 7 juin 2007 à 15 h30

Salle de Visioconférences - Bâtiment 25
IPHC, 23 rue du Loess, Strasbourg-Cronenbourg

Abstract :

Nuclear structure of nuclei in the valley of stability is determined by the mean field concept, where protons and neutrons create their own potential. The majority of the states in these nuclei are described by the shell model. In contrast weakly bound nuclear systems, e.g. light nuclei off the stability valley show strong deviations from the shell model due to clustering. Weakly bound states in nuclei will therefore show new phenomena. Clustering into α particles appears in excited states if the binding energy per nucleon is smaller than in α particles. A precipitation of the fermion gas (or liquid) into a Bose gas of α particles will take place in N=Z nuclei at the thresholds for the decomposition into clusters. The properties of the condensed states and their observation in compound nucleus decay are discussed. The considerations are linked to the very high chemical potential for α particles and the properties of the α-α potential. A similar shape of a molecular potential is observed in the 16O-α system. These molecular potentials are also the basis for the formation of covalently bound nuclear molecules in neutron-rich Be, C and Ne isotopes. The observation of an intrinsically reflection asymmetric molecular shape in 21Ne with its rotational bands as parity doublets is reported. Personnes a contacter :

Sandrine COURTIN

Florent HAAS