Slow and fast high-spin sequences in 158Er.

LBL-19598 Slow and Fast High-Spin Sequences in 158Er P.O. Tjom,+ R.M. Diamond, J.C. Bacelar, E.M. Beck, M.A. Deleplanque, J.E. Draper,+ and F.S. Stephens Nuclear Science Division Lawrence Berkeley Laboratory University of California Berkeley, California 94720 Two branches are observed feeding the 38+ level of the yrast line in 158Er. Two -i.2 MeV cascade transitions constitute a fast(< 1 ps) collective component, probably with only minor changes in shape and structure from those at lower spin. Four slower y rays (> 2 ps) suggest a transition to a different shape and structure, most likely to an oblate 46+ state with all valence particles maximally aligned, a band termination. This work was supported by the Director, Office of Energy Research, Division ~ of Nuclear Physics of the Office of High Energy and Nuclear Physics of the U.S. Department of Energy under Contract DE-AC03-76SF00098. + On leave from the Institute of Physics, University of Oslo, Norway +university of California, Davis