NOVEL DECAY MODES OF HIGH-K ISOMERS - TUNNELING IN A TRIAXIAL LANDSCAPE

The nucleus W-176 has been studied using the reaction Nd-150(Si-30,4n) , with prompt and delayed gamma-gamma coincidence techniques. A K = 14 isomer (t(1/2) approximate to 70 ns) is found to exhibit a unique dec ay pattern, primarily decaying to K = 0 states, in contrast to all pre viously studied high-K isomers. Calculations have been performed of bo th Coriolis mixing and tunneling through a potential barrier in the tr iaxial degree of freedom to understand these unusual decays. While Cor iolis mixing models do not reproduce the variations in the decay patte rns in neighboring nuclei, the tunneling calculations are remarkably s uccessful.