Monte Carlo Simulation to relate primary and final fragments mass and kinetic energy distribution from low energy fission of $^{234}U$

TL;DR

This study uses Monte Carlo simulations to connect primary and final fragment distributions in low energy uranium-234 fission, clarifying experimental observations and reproducing key features of the measured data.

Contribution

The paper introduces a numerical experiment that models the relationship between primary and final fragment distributions, explaining experimental peaks without assuming initial peak structures.

Findings

Reproduces the experimental peak around m=109 in kinetic energy distribution

Shows a depletion from m=121 to m=129 in the final fragment mass distribution

Successfully matches experimental data on neutron emission and kinetic energy as functions of mass

Abstract

The kinetic energy distribution as a function of mass of final fragments (m) from low energy fission of $^{234}U$, measured with the Lohengrin spectrometer by Belhafaf et al. presents a peak around m=108 and another around m = 122. The authors attribute the first peak to the evaporation of a large number of neutrons around the corresponding mass number; and the second peak to the distribution of the primary fragment kinetic energy. Nevertheless, the theoretical calculations related to primary distribution made by Faust et al. do not result in a peak around m = 122. In order to clarify this apparent controversy, we have made a numerical experiment in which the masses and the kinetic energy of final fragments are calculated, assuming an initial distribution of the kinetic energy without peaks on the standard deviation as function of fragment mass. As a result we obtain a pronounced peak on the standard deviation of the kinetic energy distribution around m = 109, a depletion from m = 121 to m = 129, and an small peak around m = 122, which is not as big as the measured by Belhafaf et al. Our simulation also reproduces the experimental results on the yield of the final mass, the average number of emitted neutrons as a function of the provisional mass (calculated from the values of the final kinetic energy of the complementary fragments) and the average value of fragment kinetic energy as a function of the final mass.