Fission and spallation data evaluation using induced-activity method

Abstract

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 238 U, 232 Th and 181 Ta photofission at the bremsstrahlung end-point energies of 50 and 3500 MeV, and from 241 Am, 238 U and 237 Np 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 238 U and 232 Th targets at the bremsstrahlung end-point energies of 50 and 3500 MeV. 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. PACS numbers: 25.40.Sc, 25.85.-w * Electronic address: gayane@if.usp.br arXiv:1509.00226v1 [nucl-ex] 1 Sep 2015

Systematic study of fission modes in the proton-induced fission of actinide and pre-actinide

“…The number of intermediate mass fragments (IMFs) from 241 Am target in the mass range < < A 28 6 9and the cross sections of heavy elements in the mass range < < A 150 191 from 241 Am, 238 U and 237 Np targets have been obtained in an off-line experiment using an induced-activity method [33]. These correspond to the new measured data that are further analyzed to take into account the cumulative contribution from decay nuclides [34].…”

“…In the case where the cross section of a given isotope includes a contribution from the b  -decay of neighboring unstable isobars, the cross section calculation becomes more complicated. If the formation cross section of the parent isotope is known from the experimental data, or if it can be estimated on the basis of other sources, the independent cross sections of daughter nuclei can be calculated by the relation [33]:…”

Spallation reactions induced by 4.4 GeV deuterons on lead isotopes

“…During the calculation of the production cross section from the 204 Pb target, the obtained cross section was corrected according to the fraction of the corresponding contribution to the cross section from other targets. If the formation cross section of the parent isotope is known from experimental data, or if it can be estimated on the basis of other sources, the independent cross sections of daughter nuclei can be calculated using the relation [16]:…”

Energy dependence of exotic nuclei production cross sections by photofission reaction in GDR range

“…far away from the valley of stability, nuclei having characteristically different structure and dynamics need to be studied. In this context the study of mass and charge distribution in low energy photon [1][2][3], neutron [1] and proton [4] induced fission of actinides, where fission fragments are primarily neutron-rich, is found extremely important.…”