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 (\n $$\\hbox {E}_{f} \\approx 200~\\hbox {MeV}$$\n ). While the TKE release in the $$^{239}\\hbox {Pu}$$\n (n,f) reaction was previously measured up to 50 MeV incident neutron energy (\n $$\\hbox {E}_{n}$$\n ), there were features in TKE release at the highest values of $$\\hbox {E}_{n}$$\n that were puzzling. There was a marked flattening of TKE release from $$\\hbox {E}_{n} = 30$$\n to 50 MeV, in disagreement with the clearly decreasing TKE observed from $$\\hbox {E}_{n} = 0.5$$\n to 30 MeV. To verify and clarify this trend, TKE measurements at higher values of $$\\hbox {E}_n$$\n were made. We present absolute measurements of TKE release in $$^{239}\\hbox {Pu}$$\n (n,f) from $$\\hbox {E}_{n} = 2.4$$\n 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.