The fast neutron induced fission of $^{240}$Pu and $^{242}$Pu

TL;DR

This study measures the total kinetic energy release in fast neutron-induced fission of plutonium isotopes and compares results with models and previous experiments, revealing better precision but some discrepancies in distribution variances.

Contribution

First absolute measurements of TKE in fast neutron fission of $^{240}$Pu and $^{242}$Pu, with detailed comparison to models and prior data, highlighting differences in variance predictions.

Findings

TKE decreases non-linearly with neutron energy.

Measurements agree with previous data for specific neutron energies.

Variance of TKE distributions is lower than model predictions.

Abstract

We report the measurement of the TKE release in the fast neutron induced fission of $^{240}$Pu and $^{242}$Pu. The results are compared to the predictions of the GEF model, the CGMF model, and the model of Denisov and Sedykh as well as previous experimental work on these reactions. Our absolute measurements of the TKE release are in good agreement with the previous measurements of Nethaway \textit{et al.} for the interaction of 14.8 MeV neutrons with $^{240}$Pu \cite{Nethaway} and of Winkelmann and Aumann for the interaction of 15 MeV neutrons with $^{242}$Pu \cite{Winkelmann}. The general trends of the measured TKE values agree with phenomenological models but the variances of the TKE distributions are significantly less than predicted by various models. The mean post neutron emission TKE release decreases non- linearly with increasing neutron energy and can be represented as TKE(MeV) = 175.8 $\pm$ 0.3 - (2. 4 $\pm$ 0.8)log$_{10}$E$_n$ - (1.4 $\pm$0.4)log$_{10}$E$_{n}^2$ for $^{240}$Pu and TKE(MeV) = 177.1 $\pm$ 0.3 - (1.2 $\pm$ 0.9)log$_{10}$E$_n$ - (1.8 $\pm$0.5)log$_{10}$E$_{n}^2$ for $^{242}$Pu.