Octupole Deformation in Neutron Rich 145,147 La Nuclei
- Received Date: 1999-03-02
- Accepted Date: 1900-01-01
- Available Online: 2000-04-05
Abstract: The level schemes with high spin states in neutron-rich145,147La nuclei have been established from the study of prompt γ-rays emitted in the spontaneous fission of 252Cf. Many new levels and γ transitions have been idenfified. The highest spin states in both nuclei were expanded up to(41/2+)and (43/2-)respectively. The alternating parity band structures and strong E1 transitions between negative-and positive-parity bands show strong octupole deformation. The collective bands observed in 145La give evidence for co-existence and competition between symmetric and asymmetric shapes. From the systematic comparison with the neighboring isotones, the s=+i bands in both nuclei most probably originate from the single particle πh11/2 orbital coupling with the neighboring even-even cores, respectively. Band crossing of the πh11/2 bands was found aroundω≈0.26—0.30MeV and these backbends are related to the alignment of two i13/2 neutrons from cranked shell model calculations.