Subbarrier resonances in fission of /sup 234/U, /sup 236/U, and /sup 240/Pu

The subbarrier fission probabilities of /sup 234/U, /sup 236/U, and /sup 240/Pu have been studied using the (d,pf) reaction, with improved statistics over previous measurements. A number of previously unidentified resonances have been found in /sup 236/U and /sup 240/Pu; in addition, a shelf or plateau from 4.0 to 4.5 MeV in the fission probability of /sup 234/U has been observed. The fission probabilities have been analyzed using the doorway-state model, and barrier parameters, transition state energies, and the energies of K/sup ..pi../ = 0/sup +/ fission vibrations have been determined. The systematic behavior of transition state and K/sup ..pi../ = 0/sup +/ resonance energies with varying N and Z is discussed.