Octupole states have been studied systematically in the deformed actinide nuclei ${}^{230}\mathrm{Th},$ ${}^{234,236,238}\mathrm{U},$ ${}^{240}\mathrm{Pu},$ ${}^{246}\mathrm{Cm},$ and ${}^{250}\mathrm{Cf}$ using the interacting boson approximation 1. Parameters for the positive parity cores were set by reproducing data from the ground state and γ-vibration bands with the extended consistent-$Q$ formalism. A prescription for setting the parameter ${\epsilon }_f$ systematically was adopted for the calculations of the octupole bands. The ordering of the $K^{\pi }{=0\mathrm{}}^{-},$ $1^{-},$ and $2^{-}$ bands and the behavior of many $E1\mathrm{}$ and $E3\mathrm{}$ transitions are well reproduced with a narrow range of parameters, particularly when the existence of a $N=164\mathrm{}$ subshell gap is assumed. It is predicted that in ${}^{246}\mathrm{Cm}$ and ${}^{250}\mathrm{Cf}$ the $K^{\pi }{=3\mathrm{}}^{-}$ octupole states built on the ground state are located above 6 MeV and are strongly fragmented.

• Received 25 March 1998

DOI:https://doi.org/10.1103/PhysRevC.58.1500