- and Hyperdeformed States in the Actinide Region

The ²³⁹Pu(d,pf)²⁴⁰Pu, and the ²³³U(d,pf)²³⁴U reactions have been studied with high energy resolution. The observed fission resonances were described as members of rotational bands with rotational parameters characteristic to super- and hyperdeformed nuclear shapes. Information on the K values of the bands and for the J values of the band members has been obtained from fission fragment angular distribution measurements. The level density of the most strongly excited states has been compared to the prediction of the back-shifted Fermi-gas formula and the energy of the ground state in the second and third minimum has been estimated for ²⁴⁰Pu and ²³⁴U, respectively. The fission fragment mass distribution of the hyperdeformed states in ²³⁶U has also been measured. The width of the mass distribution, coincident with the hyperdeformed bands, is significantly smaller than the ones obtained in coincidence with background regions below and above the resonances, which suggests a pear-shaped di-nuclear configuration of ²³⁶U in the third well of the potential barrier.