Relative mass yields in proton induced fission on natural uranium, from delayed gamma rays analysis

The Ge(Li) spectrometric technique was used to study the delayed gamma rays of the products generated in the 11.2-13.2 MeV proton induced fission on natural uranium. The activity values have been normalized to the analytical expression of the yield, given by the coexistence equation of genetically related nuclides and giving the growth and the decay in time of the gamma emitters. Relative yields of nine isobaric chains have been obtained. The complementary points have been evaluated by taking into account the experimental value of the average number of emitted neutrons for each mass number of the identified chain. The mass yield data were compared with the Gaussian curves. The ratio of the yields of the isobaric chains of atomic masses 99 and 112 has been measured in the range of proton energies from 11.2 to 13.2 MeV and the behaviour of the total fission cross section has been deduced