Regular Article - Theoretical Physics
Influence of energy partition in fission and pre-neutron fragment distributions on post-neutron fragment yields, application for 235U(nth,f)
University of Bucharest, Faculty of Physics, POB MG-11, str. Atomistilor 405, Magurele, 77125, Bucharest, Romania
Accepted: 10 June 2022
Published online: 11 July 2022
The key role in the calculation of post neutron fragment yields (independent fission product yields FPY) is played by (a) the pre-neutron fragment distributions Y(A,Z,TKE) and (b) the prompt neutron multiplicity (calculated in the frame of a prompt emission model). The knowledge of excitation energies of fully accelerated fragments is crucial in any modeling of prompt emission. Consequently in this paper the influence on independent FPY and kinetic energy distributions of post neutron fragments of both the pre-neutron fragment distribution and the partition of total excitation energy (TXE) is investigated. To do that, two reliable experimental Y(A,TKE) distributions of the standard fissioning nucleus 235U(nth,f) and two methods of TXE partition are considered. Nowadays two types of TXE partitions are employed in different prompt emission models, i.e. energy partitions based on different modelings at scission and different parameterizations which allow the TXE sharing by avoiding what is happening at scission. For this reason the methods of TXE partition chosen in this work belong to both types, i.e. (i) the TXE partition based on modeling at scission used in the deterministic prompt emission models PbP and DSE and (ii) the TXE partition according to the temperature ratio RT = TL/TH of complementary fully accelerated fragments (employed in the deterministic HF3D model and the probabilistic Monte-Carlo code CGMF). The independent FPY results (Y(Z,Ap) and Y(Ap)) obtained with both TXE partition methods and both Y(A,TKE) data describe reasonably well the experimental data. The use of different TXE partitions and Y(A,TKE) data does not change the position of the most pronounced peaks and dips in the Y(Ap) structure (e.g. at Ap = 134, 138, 94 and Ap = 136, 141, 97, respectively) and Y(Np) structure (e.g. at Np = 82, 84, 56 and Np = 83, respectively) only their magnitude is influenced by Y(A,TKE) distribution, while the TXE partition influences the position of less pronounced peaks and dips in the structures of Y(Ap) and Y(Np). The TXE partition has an insignificant influence on different kinetic energy distributions of post-neutron fragments, while the differences existing between the kinetic energy distributions of pre-neutron fragments are reflected in the kinetic energy distributions of post-neutron fragments.
© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2022