The modal structure of fragment mass and energy yields from the 10.3–30.0 MeV proton induced fission of 232Th and 235U

Mass and energy distributions of fragments from fission of target nuclei 232Th and 235U induced by the 10.3–30.0 MeV protons have been measured with surface-barrier silicon detectors. A new method for decomposition of experimental distributions into fragment mass and energy yields of four independent fission modes has been proposed. Main characteristics of fission modes such as distinct mode mass yields, mean masses and kinetic energies as well as variances in fragment masses and energies have been studied in relation with energy of protons. Revealed regularities in these quantities for given energy range of incident protons support the assumption that the modes S1 and S2 are initially formed in a unified asymmetric fission valley.