Pairing and two-state mixing models in Cs133

Abstract

The pairing model with configuration mixing has been applied to the odd-$A{}^{133}\mathrm{Cs}$ nucleus to study band mixing. Then, a simple two-state mixing model has been utilized for the two lowest ground and excited bands. Unique solutions were identified for the $3/2^{+}$ and $5/2^{+}$ mixing in both bands, as well as for the $E2$ matrix elements connecting the basis states. The excited band exhibited greater collectivity compared to the ground-state band. The use of a quasispin pairing operator with configuration mixing significantly improves the model's accuracy, especially in replicating experimental data for positive parity states and $E2$ transition rates.