Signature inversion in the semidecoupled pi h_{9/2} x nu i_{13/2}band of the odd-odd nucleus 172 Lu

High-spin states in the odd-odd nucleus 172Lu have been populated in a 170Er(7Li,5n) reaction at 51 MeV and the emitted -radiation was detected with the GASP array. A new semidecoupled band with the proposed 12−[541]72+[633] configuration has been established exhibiting a signature inversion. A systematic study of the signature inversion in odd-odd nuclei of the rare-earth region is presented. The variation of the inversion spin remains nearly constant for nuclei with the same N-Z, increases with N for an isotopic chain and decreases with Z for an isotonic chain. On the basis of the systematics a change of the spins by 1h is proposed for the semidecoupled bands in 180Re, 182,184Ir and 184,186Au.