Sensitivity of Prompt Neutron Multiplicity to Fission Fragment Characteristics

Abstract

The Point-by-Point (PbP) model as well as the related computer code is a useful tool to provide different prompt emission data [as a function of fragment mass A, fragment charge Z, total kinetic energy (TKE), and total average ones]. The present work focuses on the sensitivity of prompt neutron multiplicity to different properties of the fission fragments. In the construction of the fragmentation range of the PbP treatment, the use of different Z prescriptions affects the multiparametric matrices of different fragment and prompt emission quantities q(A,Z,TKE). The nonnegligible influence of how the most probable charge is considered (as unchanged charge distribution without or with the charge deviations ΔZ as a function of A or an average ΔZ value), as well as the number of Z taken at each A, is discussed. The calculated average prompt emission quantities as a function of A, as a function of TKE, and total average ones depend on the accuracy of experimental Y(A,TKE) distributions. The prompt neutron multiplicity of complementary fragments vpair (A) has a weak dependence on the total excitation energy (TXE) partition between complementary fully accelerated fragments. This assures a good prediction of the average prompt neutron multiplicity as a function of TKE and of the total average one even in the case of a rough or inappropriate TXE partition. The systematic behavior revealed by the experimental ratio vH/vpair as a function of AH together with the weak dependence of vpair(A) on the TXE partition can be exploited—in the absence of experimental v(A) information—for an indirect verification of predicted v(A).