Higher moments in the kinetic energy distribution of fission products

摘要

Data concerning the kinetic-energy distributions of selected fragments in the mass range A = 86 to A = 150 are reported for thermal neutron induced fission of U-233. The energy distributions have been measured with high resolution in energy steps of 1 MeV over energy ranges as wide as 35 Mev. Mean kinetic energies and variances as well as the lineshapes are compared to the results of a model, which assumes that fission fragments are randomly excited in the reaction, and that the temperature of the final fragments is solely determined by the reaction Q-value. From the temperature we calculate the excitation functions of the fission products, and derive by a Monte Carlo procedure the distribution functions for the kinetic energies. The excitation functions have been used too as input values into the PACE II statistical code to calculate neutron evaporation probabilities. It is shown that the model calculations give good agreement with the experimental data. (C) 2004 Elsevier B.V. All rights reserved.