Köln 2004 – wissenschaftliches Programm
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PV: Plenarvorträge
PV I
PV I: Plenarvortrag
Montag, 8. März 2004, 13:15–13:45, P
Evolution of Quadrupole Collectivity from Proton-Neutron Interaction — •Christoph Fransen — Institut für Kernphysik, Universität zu Köln
Nuclei can exhibit single-particle and collective properties.
The evolution from one extreme to the other is one of the most interesting
phenomena in nuclear structure physics. The proton-neutron (pn)
interaction (QpQn) couples the pn subsystems to form pn
symmetric and non-symmetric (mixed-symmetric) states at low energies.
The local shell structure and the nucleon numbers determine the strength of
this coupling and, consequently, the pn-structure of the nuclear wave
function.
The nuclear mass region A≈ 90 enables us to study this structural
evolution in great detail. Comprehensive data on off-yrast low-spin states
in that mass region was collected in unprecedented richness.
Clear evidence for the pn symmetry character of excited nuclear states is
obtained from measured electromagnetic transition matrix elements [1,2].
The deduced evolution of the pn symmetry character of low-lying quadrupole
excitations in this mass region will be discussed.
Supported by the DFG under Contracts No. Pi 393/1-2, Br
799/8-2/9-1,
and No. Kn 154/30 and the U.S. NSF under Grant No. PHY-0098813.
[1] N. Pietralla, et al., Phys. Rev. Lett 83, 1303
(1999), Phys. Rev. Lett 84, 3775 (2000),
[2] C. Fransen, et al., Phys. Lett. 508B, 219 (2001).