ELECTRO-FISSION OF U-238 AND TH-232

Absolute electrofission cross sections for238U and232Th in the energy region Ee=7 -65 MeV and fission fragment angular distributions for Ee=7-30 MeV have been measured. The angular distributions show strong anisotropies for low energies. The relative dipole and quadrupole contributions as a function of excitation energy are discussed in terms of the low lying fission transition states above the fission barriers. The cross sections show significant deviations from the results of some earlier measurements, in particular in the energy region above the giant dipole resonance. From the difficulties of absolute electrofission cross section measurements and the ambiguities in their interpretation it is concluded that by this time the quantitative analysis of electrofission cross sections with respect to the contributions of the giant quadrupole resonances to the fission decay channel should be regarded as rather tentative. © 1979 Springer-Verlag.