Photofission cross sections of 232Th and 236U from threshold to 8 MeV

Abstract

Measurements of the photofission cross sections of 232Th and 236U for an energy range of 5.0 to 8.0 MeV are reported. The Compton scattering facility at the Ames Laboratory Research Reactor was used for these measurements. Resonance structure at γ-ray energies of 6.3 and 7.6 MeV is observed in 232Th and at 5.3, 6.0, 6.5, and 7.5 MeV in 236U. The present results are compared with other photofission experiments and particle-induced fission studies. Suggestions for the interpretation of the resonances are given on the basis of Bohr's fission-channel theory and the existence of a double-humped fission barrier.