Characteristics of Symmetric and Asymmetric Fission Modes as a Function of the Compound Nucleus Excitation in the Proton‐Induced Fission of 233Pa, 239Np and 243Am

Average preequilibrium 〈Mnpreeq〉 average statistical prescission 〈Mnstpre〉 and postscission 〈Mnpost〉 neutron multiplicities as well as average γ‐ray multiplicity 〈Mγ〉, average energy emitted by γ‐rays 〈Eγ〉 and average energy per one gamma quantum 〈eγ〉 as a function of mass and total kinetic energy (TKE) of fission fragments were measured in the proton‐induced reactions p+232Th→233Pa, p+238U→239Np and p+242Pu→243Am (at proton energy Ep=13, 20, 40 and 55 MeV). The fragment mass and energy distributions (MEDs) have been analyzed in terms of the multimodal fission. The decomposition of the experimental MEDs onto the MEDs of the distinct modes has been fulfilled in the framework of a method that is free from any parameterization of the distinct fission mode mass distribution shapes. The main characteristics for symmetric and asymmetric modes have been studied in their dependence on the compound nucleus composition and proton energy. The manifestation of multimodal fission in average γ‐ray multiplicities 〈Mγ〉 o...