Thorium fission by 4.8 and 14 MeV neutrons
AbstractThe fission of natural Thorium byEn=4.8 and 14.0 MeV neutrons has been investigated by measuring the kinetic energies of both fragments in surface barrier detectors. The fragments were detected forEn=14.0 MeV neutron energy at 90 ° to the neutron beam, forEn=4.8 MeV at 0 ° and 90 °. The results given are the distributions of mass and of energy correlative to the fragment mass, and the correlation between anisotropy and fragment mass atEn=4.8 MeV. The average total kinetic energy before prompt neutron emission atEn=4.8 and 14.0 MeV neutron energy has been found to be

$$\overline {E_K^* } $$

=170.47±0.03 and 168.1 ± 0.05 MeV respectively. Within the limits of statistical error the anisotropy atEn=4.8 MeV is independent of the fragment mass. The results are analysed in the framework of the Two-Mode-Fission-Hypothesis. It appears, that the behaviour of the kinetic energy is too complicated as to be well described by the Two-Mode-Fission-Hypothesis. Both the Cluster Model of fission and the Fragment Shell Theory are suited to reproduce qualitatively the observed energetics of fission.