Prompt Neutron Emission in the Neutron-Induced Fission of 239Pu and 235U

A series of experiments has been performed to measure the dependence on the fragment mass and total kinetic energy of the average number and energy of prompt neutrons emitted from 235U and 239Pu fission fragments in thermal neutron induced fission. The experiments were carried out using neutrons from the PNPI WWR‐M research reactor in Gatchina. For the 239Pu target the fragment — neutron correlation measurement was also performed at the first resonance. In this case the neutron energy of the strong resonance at 0.296 eV was selected by a Sm filter which was arranged in the neutron flux from the reactor. The description of the experimental set‐up and some preliminary results of the average number and kinetic energies of prompt neutrons as a function fragment mass are presented in this article.