The Rotor-Vibrator Plus Multi-Particle-Hole Description of ¹⁵⁴Gd

Abstract

Based on the well-known rotor-vibrator model and the particle-plus-rotor model, multi-particle-hole excitations from a collective even-even core described by the rotor-vibrator is considered to describe well-deformed even-even nuclei. Like the particle-plus-rotor model, the intrinsic Vierergruppe (D2) symmetry is still preserved in the rotor-vibrator plus multi-particle-hole description. It is shown that a series of experimentally observed 0+ states in these nuclei may be interpreted as the multi-particle-hole excitations in a complementary manner to the beta and gamma vibrations described by the rotor-vibrator model. As a typical example of the model application, low-lying positive parity level energies below 1.990 MeV in the eight experimentally identified positive parity bands; a series of 0+ excitation energies up to 016+; and some experimentally known B(E2) values, E2 branching ratios, and E2/M1 and E0/E2 mixing ratios of 154Gd are fitted and compared to the experimental data. The results suggest that the multi-particle-hole-pair configuration mixing may play a role in these 0+ states.

Keywords

• rotor-vibrator
• multi-particle-hole excitation
• configuration mixing
• well-deformed nuclei