Neutron emission effects on fragment mass and kinetic energy distribution from fission of 239[sup Pu] induced by thermal neutrons

Abstract

The average of fragment kinetic energy (Ē*) and the multiplicity of prompt neutrons (ν̄) as a function of fragment mass (m*), as well as the fragment mass yield (Y(m*)) from thermal neutron‐induced fission of 239Pu have been measured by Tsuchiya et al.. In that work the mass and kinetic energy are calculated from the measured kinetic energy of one fragment and the difference of time of flight of the two complementary fragments. However they do not present their results about the standard deviation σE*(m*). In this work we have made a numerical simulation of that experiment which reproduces its results, assuming an initial distribution of the primary fragment kinetic energy (E(A)) with a constant value of the standard deviation as function of fragment mass (σE(A)). As a result of the simulation we obtain the dependence σE*(m*) which presents an enhancement between m* = 92 and m* = 110, and a peak at m* = 121.