Multiple Octupole-Band Structures in $^{238}$U

An experiment with a $^{207}$Pb beam (1400 MeV) has been carried out on a thick $^{238}$U target at Gammasphere. The level scheme of the $^{238}$U has been extended significantly. The signature-partner bands of the known K=1 and K=2 octople bands were uncovered for the first time, in addition to another newly observed postive-parity band. This band decays to all the K=0, 1 and 2 octuple bands with an intensity much stronger than that observed for the deexcitation to the groundstate band. Its most important features can be related to a double octuple phonon excitation. The comparison between this band and a similar one in $^{240}$Pu [1] sheds more light on the recently proposed concept of octuple phonon condensation [2].\\[4pt] [1] X. Wang et al., Phys. Rev. Lett. 102, 122501(2009).\\[0pt] [2] S. Frauendorf, Phys. Rev. C 77, 021304(R)(2008)