Level structure of the N=88 isotones ¹⁴⁹Pm, ¹⁵¹Eu and ¹⁵³Tb

The level structures of the N=88 isotones ¹⁴⁹Pm, ¹⁵¹Eu and ¹⁵³Tb are studied in a version of the unified vibrational model which incorporates both pairing effects and anharmonicity in the core vibrations. The proton quasiparticle states in the Z=50-82 shell are coupled to anharmonic vibrations of the corresponding even cores. The calculated level energies, spectroscopic factor and E2 transition strengths are compared with available experimental data and predictions of other theoretical calculations.