High-spin states in odd-odd nuclei

High-spin states in doubly odd nuclei of 124Cs, 126Cs and 124La have been investigated by γ ray spectroscopy. Rotational bands of πh11/2 x νh11/2 configuration have been assigned by the blocking argument on the first band crossing frequencies for neighboring odd-A nuclei. In cesium isotopes, the signature inversion of quasiparticle routhians has been observed. The spin of the band head in 124Cs has been determined to be (7+) by means of spectroscopic method. This spin assignment implies that the signature inversion occurs at low spin. The signature dependence becomes normal at higher spins than 17h. The occurrence of the signature inversion in the A ∼ 130 mass region is discussed by comparing excitation energies, transition intensities and the shell-model orbits of valence nucleons with those of rare-earth nuclei. (orig.)