Transition probabilities and interacting boson-fermion model description of positive parity states in117Sb

The Doppler shift attenuation method was used to determine lifetimes in the picosecond region for excited states of ${}^{117}\mathrm{Sb}$ populated with the $(\alpha ,2n\gamma )$ reaction at $E_{\alpha }=27.2\mathrm{}\mathrm{MeV}.$ Interacting boson-fermion model calculations explain reasonably well the main features of the positive parity levels known up to about 2.5 MeV excitation. The mixing of the lowest one-quasiparticle ${9/2}^{+}$ state with the intruder $\mathrm{}(2p-1h)\mathrm{}$ ${9/2}^{+}$ state, as well as the quadrupole deformation of the intruder band are also discussed.