First observation of the orbital in the mass regionW. Urban1, J.A. Pinston2, T. Rzaca-Urban1, A. Zlomaniec1, G. Simpson3, J.L. Durell4, W.R. Phillips4, A.G. Smith4, B.J. Varley4, I. Ahmad5 and N. Schulz6
1 Institute of Experimental Physics, Warsaw University, ul. Hoza 69, 00-681 Warszawa, Poland
2 Institut des Sciences Nucléaires, F-38026 Grenoble Cedex, France
3 Institut Laue-Langevin, F-38042 Grenoble Cedex, France
4 Schuster Laboratory, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
5 Argonne National Laboratory, Argonne, IL 60439, USA
6 Institut de Recherches Subatomiques UMR7500, CNRS-IN2P3 et Université Louis Pasteur, 67037 Strasbourg, France
(Received: 11 September 2002 / Published online: 17 January 2003)
A new band, populated by the spontaneous fission of 248Cm and studied by means of prompt -ray spectroscopy using the EUROGAM2 array, was observed in 99Zr. The 1038.8 keV band head with a half-life T1/2=54(10) ns is interpreted as a K-isomer, corresponding to the 9/2 neutron-hole excitation. It is the first observation of this orbital in the mass region. The quadrupole moment, Q0=3.9(3) eb deduced for the new band indicates a large deformation of , which is produced by a specific shape-coexistence mechanism, known in other regions and now found in the nuclei.
23.20.Lv - Gamma transitions and level energies.
21.60.Cs - Shell model.
25.85.Ca - Spontaneous fission.
27.60.+j - .
© Società Italiana di Fisica, Springer-Verlag 2003