The neutron-induced fission cross section of ${}_{}{}^{230}{}_{}{}^{}\mathrm{Th}$ near 720 keV is resolved into sharp structures interpreted as two rotational bands with opposite parities, indicating an asymmetrically deformed third minimum in the fission barrier.

• Received 7 August 1978

DOI:https://doi.org/10.1103/PhysRevLett.41.1282