Octupole correlations in stable nucleus ¹⁵³Eu within reflection-asymmetric particle rotor model*

The observed low-lying positive- and negative-parity bands in the stable nucleus 153 Eu are investigated using the reflection-asymmetric triaxial particle rotor model. The experimental energy spectra, energy staggering parameters, and intraband and transition probabilities are well reproduced. The calculated interband values are found to depend sensitively on the octupole deformation parameter , although the energy spectra and intraband and transitions can be reproduced without the octupole degree of freedom. The observed enhanced transition probabilities can be reproduced with . The detailed analysis of the intrinsic wave functions shows these nearly degenerate positive- and negative-parity bands are built on two individual proton configurations, i.e. , dominated by and , respectively, which differs from the parity doublet bands built on a single parity-mixed configuration.