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Dynamics of α-clusters in N = Z nuclei

  • W. von OertzenEmail author
Nuclear Structure and Reactions

Abstract.

The systematics for binding energies per α-particle in N = Z nuclei, E /N α, are studied up to 164Pb. It is shown that, although a geometrical model can be used to explain the systematics for light nuclei, the binding energy per α-particle exhibits structures which are due to the well-known shells of the mean field of nucleons in nuclei. The overall dependence of E /N α on N α in N = Z nuclei (for the ground-state masses) can be described in a liquid-drop model of α-particles. Conditions for a phase change with the formation of an α-particle condensate, a dilute Bose gas in excited compound nuclei are discussed for E /N α = 0, at the thresholds. This is achieved when the binding energy per nucleon in nuclei is equal to or smaller than in the α-cluster. At somewhat smaller excitation energies the appearance of a Bose gas with a closed-shell core (N = Z, e.g. of 40Ca) is proposed within the same concept. The experimental observation of the decay of such condensed α-particle states is proposed with the coherent emission of several correlated α-particles not described by the Hauser-Feshbach approach for compound-nucleus decay. This decay will be observed by the emission of unbound resonances in the form of 8Be and 12C * (0+ 2) clusters.

PACS.

21.10.-k Properties of nuclei; nuclear energy levels 21.60.Gx Cluster models 

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Copyright information

© Società Italiana di Fisica and Springer-Verlag 2006

Authors and Affiliations

  1. 1.Fachbereich PhysikFreie Universität BerlinBerlinGermany
  2. 2.Hahn-Meitner-Institut BerlinBerlinGermany

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