Electric dipole moments in 230, 232U and implications for tetrahedral shapes
The nuclei 230U and 232U were populated in the compound nucleus reactions 232Th(α,6n) and 232Th(α,4n), respectively. Gamma rays from these nuclei were observed in coincidence with a recoil detector. Acomprehensive set of in-band E2 transitions were observed in the lowest lying negative-parity band of 232Uwhile one E2 transition was also observed for 230U. These allowed B(E1; I - → I + - 1)/B(E2; I - → I - - 2) ratios to be extracted and compared with systematics. The values are similar to those of their Th and Ra isotones. The possibility of a tetrahedral shape for the negative-parity U bands appears difficult to reconcile with the measured Q2 values for the isotone 226Ra. © 2010 The American Physical Society.