Observation of signature partner bands in Sb117

Rotational band structures and low-lying single-particle levels in Sb-117 have been populated using reaction In-115(alpha, 2n) Sb-117 at a beam energy of 28 MeV and investigated using gamma-ray spectroscopic techniques. The existing level scheme has been extended with the observation of 31 new transitions. The signature partner of the band structure based on the configuration of pi g(7/2) circle times 2p-2h of the Sn-116 core has been established in Sb-117 for the first time. Several single-particle nonyrast transitions connecting to various band structures have also been identified. Measurements of the DCO ratios, polarization asymmetry and angular distribution of the observed gamma rays have been carried out to assign the spin-parities to the levels of all the band structures and the low-lying single-particle states, populated in the present work. The spin-parities are also determined for the states of the two previously unassigned bands. The lower-spin structures have been interpreted on the basis of large-scale shell-model calculations using OXBASH. Particle Rotor Model (PRM) calculations have been carried out to explain the large signature splitting of the observed signature partner bands.