High-K isomers in neutron-rich hafnium nuclei at and beyond the stability line

Pulsed U-238 and Pb-208 beams have been used to populate multi-quasiparticl e high-K isomers in neutron-rich hafnium isotopes at and beyond the line of beta-stability, via inelastic excitation and transfer. Spectroscopic prope rties and configuration assignments of several new high-K isomers are compa red with earlier theoretical predictions. A striking example of the robustn ess of the K quantum number is demonstrated by the observed competition bet ween E1 and E3 decay modes in Hf-180, the heaviest stable isotope of the el ement. [S0556-2813(99)50503-7].