Isotopic Distributions and Element Yields in the Photofission of 235U and 238U with 12-, 15-, 20- and 30-MeV Bremsstrahlung

Abstract

Using chemical separation techniques, γ-spectrometry of fission product catcherfoils and direct γ-spectrometry of irradiated uraniumsamples, the fractional independent or cumulative chain yields of about 50 fission products were measured for the photofission of 235U and 238U with 12-, 15-, 20- and 30-MeV bremsstrahlung. In addiation a number of fractional independent chain yields were calculated using the charge distribution curves. This enables us to study the isotopic distributions for Kr, Rb, Sr, Sn, Sb, Te, I, Xe, Cs and Ba isotopes for the photofission of 235U and for Rb, Sn, Sb, Te, I and Xe isotopes for the photofission of 238U. The corresponding element yields for all investigated isotopic distributions were calculated. As well for the photofission of 235U as for 238U at all bremsstrahlung end point energies a very low yield of 136I and 134Sb was obtained.