Level structure of Cs-120

Excited states of the Cs-120 nucleus have been studied by using in-beam gam ma -ray spectroscopy with the Ag-107(O-16,3n)(120)Csfusion-evaporation reac tion at a beam energy of 85 MeV. The level scheme of Cs-120 has been determ ined using gamma-gamma coincidence and gamma-gamma angular correlation anal yses. We suggest that the spin of the lowest state for the pi (h11/2) circl e times vh(11/2) quasiparticle band should be 9(+), which is 2h higher in a ngular momentum than that of previous spin assignment. A spin inversion bet ween the favored and the unfavored states in this positive-parity band was observed below I = 19h. In addition, the spin assignment of the negative-pa rity band with small signature splitting has also been made for the band he ad with I-pi = 8(-). These two rotational bands are found to be connected t o each other at lower spin states and to the high-spin 7(-) isomer with hal f-life of T-1/2 61.2 s through different decay paths. (C) 2001 Elsevier Sci ence B.V. All rights reserved.