Excited states and signature inversion in Cs116

Excited states have been observed for the first time in the very neutron-deficient, odd-odd nucleus, 55116Cs61. The assignment to Cs116 has been made by the detection of γ rays in coincidence with evaporated charged particles and with evaporation residues. The observed states form a rotational band which has been assigned to the ν(h11/2)π(h11/2) configuration. Tentative spin assignments have been made on the basis of systematic comparisons with neighboring cesium isotopes. A low-spin signature inversion is observed in the band at a rotational frequency of about 0.23 MeV/. The observed signature inversions in the odd-odd Cs116-126 isotopes have been compared with the results of extended total Routhian surface calculations, in which signature inversion arises as a consequence of quadrupole-pairing correlations and triaxial deformation. As previously shown for some of the odd-odd 120 isotopes, the calculations reproduce the signature inversions reasonably well.