In-beam spectroscopy of224Th

A rotational band with states of alternating parity has been populated in224Th via the208Pb(18O, 2n) reaction. Spins up to Iπ=10>+ (11−) are identified. Stretched El and E2 transitions compete in the deexcitation, the average ratio of the reduced transition probabilities being B(E1)/B(E2)=(1.5±0.4)×10−6 fm−2. This ratio implies that224Th has one of the largest intrinsic electric dipole moments observed so far.