Cold spontaneous fission processes of252Cf and the structure of neutron rich Ba and La nuclei

Rare cold (zero neutron emission and low excitation energy) binary fission, cold α and 10Be-accompanied ternary fission and cold fission with two neutrons emitted at scission and new nuclear structure effects have been observed in the spontaneous fission of 252Cf. Evidence for stable octupole deformation in 143,144,146 Ba and 145,147La are presented. The roles of rotation in both enhancing and quenching stable octupole deformation are observed. In 145La one has a new class of shape coexistence with symmetric and asymmetric rotational bands.