Fission and spallation data evaluation using induced-activity method

摘要

The induced-activity investigations in off-line analysis performed in different experiments, concerning pre-actinide and actinide nuclei, are here presented and discussed. Generalized expressions for the determination of independent yields/cross sections of radioactive nuclei, formed in the targets, are derived and analysed. The fragment mass distribution from U-238, Th-232 and Ta-181 photofission at the bremsstrahlung end-point energies of 50 and 3500 MeV, and from Am-241, U-238 and Np-237 fission induced by 660 MeV protons, are scrutinized from the point of view of the multimodal fission approach. The results of these studies are hence compared with theoretical model calculations using the CRISP code. A multimodal fission option has been added to this code, which allows to account the contribution of symmetric and asymmetric (superasymmetric) fission to the total fission yield. Moreover, this work contains the general results obtained in the analysis of the isomer ratios of fission fragments from U-238 and Th-232 targets at the bremsstrahlung end-point energies of 50 and 3500MeV. Moreover, the values of the average angular momenta of primary fragments are estimated by using the statistical model calculation. We subsequently discuss the complex particle-induced reaction, such as heavy ions and deuterons, by using the thick-target thick-catcher technique and the two-step vector model framework as well. This is accomplished in order to present the investigation of the main processes (fission, spallation and (multi) fragmentation) in intermediate-and high-energy ranges of the incident particle. The set of experimental data, presented in this work, encompasses not merely the data as total production cross sections. Notwithstanding, it further covers other data, as individual yields/cross sections, charge, mass and spin distributions of the reaction fragments, as well as kinematic features. These sources of experimental data can serve as a consistent set of benchmarking data, still necessary for the study of heavy nuclei. Besides, it is also useful for technological applications, from astrophysics and environmental sciences to accelerator technology and accelerator-based nuclear waste transmutation and energy amplification as well.