Eur. Phys. J. A 12, 15-28 (2001)

Study of ¹⁶⁹Hf at high rotational frequency

K.A. Schmidt¹, M. Bergström¹, G.B. Hagemann¹, B. Herskind¹, G. Sletten¹, P.G. Varmette¹, J. Domscheit², H. Hübel², S.W. Ødegård³, S. Frattini⁴, A. Bracco⁴, B. Million⁴, M.P. Carpenter⁵, R.V.F. Janssens⁵, T.L. Khoo⁵, T. Lauritsen⁵, C.J. Lister⁵, S. Siem⁵, I. Wiedenhöver⁵, D.J. Hartley⁶, L.L. Riedinger⁶, A. Maj⁷, W.C. Ma⁸ and R. Terry<sup>8

1</sup>  The Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark
²  Institut für Strahlen- und Kernphysik, University of Bonn, Nussallee 14-16, D-53115, Bonn, Germany
³  Department of Physics, University of Oslo, Norway
⁴  Dipartimento di Fisica, University of Milano and INFN Milano, Italy
⁵  Argonne National Laboratory, Argonne, Illinois 60439, USA
⁶  Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA
⁷  Niewodniczanski Institute of Nuclear Physics, Krakov, Poland
⁸  Mississippi State University, Mississippi State, MS 39762, USA

hagemann@nbi.dk

(Received: 23 March 2001 / Revised version: 20 September 2001 Communicated by D. Schwalm )

Abstract
High-spin properties of the nucleus ¹⁶⁹Hf have been studied through the fusion evaporation reaction ⁹⁶Zr(⁷⁶Ge,3n)¹⁶⁹Hf at a beam energy of 310 MeV. The known rotational bands have been extended considerably and 6 new bands have been established, four of which form coupled bands with pronounced M1 connections. Quasiparticle assignments are suggested for the new band structures, and it appears that coupling to vibrational degrees of freedom plays a role. Both coupled bands involve the excitation of quasiprotons. In the region of highest spin, a large alignment gain is interpreted in terms of a mixed crossing where an h_9/2 and an h_11/2 quasiproton provide the two signatures of the aligning configuration.

PACS
21.10.-k - Properties of nuclei; nuclear energy levels.
23.20.Lv - Gamma transitions and level energies.
25.70.-z - Low and intermediate energy heavy-ion reactions.
27.70.+q - .

© Società Italiana di Fisica, Springer-Verlag 2001