Eur. Phys. J. A 10, 13-19
New excited superdeformed bands in heavy
nuclei: Clue for an
octupole softness near the
gap at large deformation
A. Prévost1, N. Buforn1, A. Astier1, R. Duffait1, M. Meyer1, S. Perriès1, N. Redon1, O. Stézowski1, A. Bauchet2, I. Deloncle2, M.G. Porquet2, A. Görgen3, H. Hübel3, E. Mergel3, S. Neumann3, D. Roßbach3, N. Nenoff3, G. Schönwaßer3, A.N. Wilson4, R. Lucas5, F.A. Beck6, D. Curien6, G. Duchêne6, B.J.P. Gall6, N. Kintz6, J.P. Vivien6 and D.M. Cullen7
1 IPN Lyon, IN2P3/CNRS, Université Lyon-1, F-69622 Villeurbanne Cedex, France
2 CSNSM Orsay, IN2P3/CNRS, Université Paris-Sud, F-91405 Orsay Campus, France
3 Institut für Strahlen- und Kernphysik, Universität Bonn, Nussallee 14-16, D-53115 Bonn, Germany
4 Department of Physics, University of York, York Y01 5DD, United Kingdom
5 CEA/Saclay, DAPNIA/SPhN, F-91191 Gif sur Yvette, France
6 IReS Strasbourg, IN2P3/CNRS, Université Louis Pasteur, F-67037 Strasbourg Cedex 2, France
7 Oliver Lodge Laboratory, Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom
astier@ipnl.in2p3.fr
(Received: 20 December 2000 Communicated by D. Schwalm )
Abstract
We report the identification of six new superdeformed (SD)
bands in
197,198Pb observed with the EUROBALL IV
spectrometer. The results are interpreted in the framework of cranked
Hartree-Fock calculations with approximate projection on the particle
number by means of the Lipkin-Nogami method. A mixing between
quasi-particle excitations and an octupole vibration is suggested in
the two SD isotopes. We have estimated the ordering of the neutron
valence orbitals and confirm indirectly a N=118 SD gap.
21.10.Re - Collective levels.
21.60.Ev - Collective models.
23.20.Lv - Gamma transitions and level energies.
27.80.+w - 190

© Società Italiana di Fisica, Springer-Verlag 2001