The Ratio of the Uranium-238 to Uranium-235 Fission Cross Sections from 1 to 5 MeV

Measurements of the ²³⁸U:²³⁵U fission cross section ratio were carried out in the 2 to 3 MeV region using two different methods to determine the relative masses. The energy dependence of the ratio was measured from 1 to 5 MeV and normalized to the results at 2.5 MeV. The measured value of the ratio at 2.5 MeV is 0.432 ± 0.004.