Doublet bands in 128La and systematic features of energy separationof doublet bands observed in the A～130 mass region

High spin states of 128La have been studied through the fusion-evaporation reaction 118Sn(14N,4n) 128La at a beam energy of 69 MeV. A positive-parity side band with the same configuration as that of the yrast band has been identified. Moreover, it is noted that the energy separation △E(I) = E(I)side-E(I)yrast of all doublet bands reported in odd-odd nuclei in the A～130 mass region exhibit a staggering pattern systematically, and they stagger up at even-spin and stagger down at odd-spin.     

Band Structures of the Nucleus 129Cs

High-spin states in ^129Cs are populated via the ^122Sn （^11B, 4n） reaction at beam energies of 55 and 60MeV. Two additional bands are placed in the level scheme and the previously known bands are extended to higher spins. The results are compared to the cranked shell model calculations and to the systematics of the adjacent Cs isotpoes. One of the new bands is interpreted as the 7-vibrational band built on the πh11/2 orbital. The possible configuration for another new band is discussed. Upbend caused by （Vh11/2）^2 alignment is observed both in the favored and unfavored sequences of the πh11/2 configuration. The band based on the πgτ/2 configuration at low spins forks around spin 17//2, and the two different S-bands are attributed to （Vh11/2）^2 and （πh11/2）^2 rotational alignments, respectively.