Doubly decoupled structure in odd-odd Ir178-186 nuclei

High-spin states in (178,180) Ir have been studied via the 152,154Sm(P, 5n gamma) reactions through excitation functions, x-gamma and gamma-gamma -t c oincidence measurements. A doubly decoupled band has been identified in eac h of the isotopes. The level spacings for such structures in odd-odd Ir178- 188 have been inspected and thus a regular level staggering as a function o f the neutron number is revealed. This particular phenomenon may be associa ted with bandmixing at lower excitation energies.