FRAGMENT MASS AND KINETIC-ENERGY DISTRIBUTIONS FOR THE PHOTOFISSION OF U-238 WITH 12-MEV, 15-MEV, 20-MEV, 30-MEV, AND 70-MEV BREMSSTRAHLUNG

Energy correlation measurements with semiconductor detectors were performed for the photofission of U238 with 12-, 15-, 20-, 30-, and 70-MeV bremsstrahlung. The behavior of the mass distribution with changing total kinetic energy of the fragments and with changing excitation energy of the compound nucleus is deduced. The distribution of the total fragment kinetic energy as a function of the fragment mass and as a function of the average excitation energy of the U238 compound nucleus is studied. The results are discussed in terms of the two mode and fragment-shell hypotheses. NUCLEAR REACTIONS, FISSION U238(γ,F), Eγmax=12, 15, 20, 30, 70 MeV; measured fragment energies E1, E2; deduced N(μ,EK)Eexc(Ee). © 1979 The American Physical Society.