Total kinetic energy and mass yields from the fast neutron-induced fission of $$^{239}\hbox {Pu}$$ 239 Pu

The total kinetic energy (TKE) release in fission is an important observable, constituting over 80% of the energy released in fission ( $$\hbox {E}_{f} \approx 200~\hbox {MeV}$$ ). While the TKE release in the $$^{239}\hbox {Pu}$$ (n,f) reaction was previously measured up to 50 MeV incident neutron energy ( $$\hbox {E}_{n}$$ ), there were features in TKE release at the highest values of $$\hbox {E}_{n}$$ that were puzzling. There was a marked flattening of TKE release from $$\hbox {E}_{n} = 30$$ to 50 MeV, in disagreement with the clearly decreasing TKE observed from $$\hbox {E}_{n} = 0.5$$ to 30 MeV. To verify and clarify this trend, TKE measurements at higher values of $$\hbox {E}_n$$ were made. We present absolute measurements of TKE release in $$^{239}\hbox {Pu}$$ (n,f) from $$\hbox {E}_{n} = 2.4$$ to 100 MeV. We used silicon PIN detectors to measure the fragment energies and deduce mass-yield curves using the 2E-method. We also discuss fission asymmetry and the relationships between approximate fission fragment mass and distortion.