Identification of J^π = 19/2⁺ and 23/2⁺ isomeric states in ¹²⁷Sb

The nucleus ¹²⁷Sb, which is on the neutron-rich periphery of the β-stability region, has been populated in complex nuclear reactions involving deep-inelastic and fusion-fission processes with ¹³⁶Xe beams incident on thick targets. The previously known isomer at 2325 keV in ¹²⁷Sb has been assigned spin and parity 23/2⁺, based on the measured γ-γ angular correlations and total internal conversion coefficients. The half-life has been determined to be 234(12) ns, somewhat longer than the value reported previously. The 2194 keV state has been assigned J^π = 19/2⁺ and identified as an isomer with T_1/2 = 14(1) ns, decaying by two E2 branches. The observed level energies and transition strengths are compared with the predictions of a shell model calculation. Two 15/2⁺ states have been identified close in energy, and their properties are discussed in terms of mixing between vibrational and three-quasiparticle configurations.