Hyperdeformation and clusterization in the actinide region

The U-233(d,pf)U-234, and the U-235(d,pf)U-236 reactions have been studied with high energy resolution. The observed fission resonances were described as members of rotational bands with rotational parameters characteristic of 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 third minimum has been estimated for U-234. Th, fission fragment mass distribution of the hyperdeformed states in U-236 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 U-236 in the third well of the potential barrier.