Breakdown Of K Selection In Hf-178

Coulomb activation of the four quasiparticle K-pi=16(+) Hf-178 isomer (t(1/2)=31 y) has led to the measurement of a set of E lambda matrix elements coupling the isomer band to the ground band. The present data combined with earlier Hf-178 Coulomb excitation data have probed the K components in the wave functions and revealed the onset and saturation of K mixing in low-K bands, whereas the mixing is negligible in the high-K bands. The implications can be applied to other quadrupole-deformed nuclei.