Photon and proton induced fission on heavy nuclei at intermediate energies
We present an analysis of fission induced by intermediate energy protons or photons on actinides. The 660 MeV proton induced reactions are on 241 Am, 238 U, and 237 Np targets and the Bremmstrahlung-photons with end-point energies at 50 MeV and 3500 MeV are on 232 Th and 238 U targets. The study was performed by means of the Monte Carlo simulation code CRISP. A multimodal fission extension was added to the code within an approach which accounts for the contribution of symmetric and asymmetric fission. This procedure allowed the investigation of fission cross sections, fissility, num- ber of evaporated nucleons and fission-fragment charge distributions. The comparison with experimental data show a good agreement between calculations and experiments.
Measurement of the total cross section for 238U photofission in the nucleon resonance region
Abstract We present the results of the photofission cross section for 238 U measured between 200 and 1200 MeV. In the ‡ region our results agree with existing data on the total photoabsorption cross section, while at higher energy they show no evidence of the higher nucleon resonances, clearly seen in the photon absorption on the photon, and a damping of the absolute value.
Fission of /sup 232/Th at energies up to 90 MeV
In a recent work, the yields of spallation residues from 8--90 MeV proton induced fission of /sup 232/Th were reproduced by exciton model calculations to which a fission option had been added. This allowed evaluation of the spectrum of fissioning nuclei. In this work, an extension of that calculation to the properties of the fission products is presented. Dividing the fissioning nuclei according to their fissionability, an approach is introduced which accounts for the percentage of symmetric and asymmetric fission, allows calculation of the most probable charge for a given fission product mass chain, and evaluates the numbers of pre- and post-fission neutrons. A comparison of the results of this calculation is made with extensive amounts of experimental data, and the implications of the calculation discussed.