Study of the K=8 and K=16 isomeric states in Hf-178

In Hf-178 it has been found that some 2- and 4-quasiparticle states can occ ur lower in energy than members of the collective ground state rotational b and with corresponding spin. Recent studies of these high-it isomers in the Lu, Hf, Ta, region have uncovered the existence of surprisingly large tran sition probabilities between the K = 0 ground state band and the high-K ban ds which should be forbidden if the K selection rule is valid. For the popu lation of the K-pi=8(-) isomer in Hf-178 a 2-band K-mixing model is present ed which reproduces both the long lifetime of the isomer and the strong Cou lomb excitation. In two scattering experiments at the Munich tandem acceler ator and at the UNILAC in Darmstadt we searched for excited states built on the K-pi=16(+) isomer. Micro weight quantities of 10(15) atoms in the isom eric state have been produced by a Dubna-Orsay-GSI collaboration in order t o prepare a radioactive target. In both measurements the first excited stat e built on the K-pi=16(+) isomer has been observed at an excitation energy of 357 keV with respect to the isomeric state. The intrinsic electric quadr upole moment of Q(o) = 8.2 +/- 1.1 b has been derived from the experimental data within the rigid rotor model.