High-spin structure of the neutron-rich odd-odd and isotopesM.-G. Porquet1, Ts. Venkova2, P. Petkov2, A. Bauchet1, I. Deloncle1, A. Astier3, N. Buforn3, J. Duprat4, 1, B.J.P. Gall5, C. Gautherin6, E. Gueorguieva7, F. Hoellinger5, T. Kutsarova2, R. Lucas6, M. Meyer3, A. Minkova7, N. Redon3, N. Schulz5, H. Sergolle4 and A. Wilson1
1 CSNSM, IN2P3/CNRS and Université Paris-Sud, F-91405 Orsay Campus, France
2 INRNE, BAS, 1784 Sofia, Bulgaria
3 IPNL, IN2P3/CNRS and Université Claude Bernard, F-69622 Villeurbanne, France
4 IPN, IN2P3/CNRS and Université Paris-Sud, F-91406 Orsay, France
5 IReS, IN2P3/CNRS and Université Louis Pasteur, F-67037 Strasbourg Cedex 2, France
6 DAPNIA/SPhN, CEA Saclay, F-91191 Gif-sur-Yvette, France
7 University of Sofia, Faculty of Physics, 1126 Sofia, Bulgaria
(Received: 1 June 2001 / Revised version: 15 July 2002 / Published online: 10 December 2002)
The and nuclei have been produced as fission fragments following the fusion reaction + at 145 MeV bombarding energy and studied with the Eurogam2 array. The yrast high-spin states of these four odd-odd nuclei, which are observed for the first time, consist of rotational bands in which the odd proton occupies the subshell and the odd neutron the subshell. Their behaviour as a function of spin values does not vary with the number of neutrons: as observed in the odd- N neighbouring nuclei, the motion of the odd neutron remains decoupled from the motion of the core, from N = 61 to N = 65. Moreover, the staggering observed in the yrast bands of odd-odd isotopes is strongly reduced as compared to the large values displayed by the rotational bands built on the subshell in the odd- A Rh and Ag isotopes. The results of particle-rotor calculations indicate that this reduction is related to a change of the core deformation.
21.60.Ev - Collective models.
23.20.Lv - Gamma transitions and level energies.
25.85.Ge - Charged-particle-induced fission.
27.60.+j - .
© Società Italiana di Fisica, Springer-Verlag 2002