Neutron and gamma emission in fission

The total kinetic energy freed by the mass rearrangement in binary low-energy nuclear fission is roughly of the order of 180 to 240 MeV, depending on the fissioning system. This energy is distributed at the end of the fission process between the total kinetic energy of the two fragments, the energy released by neutron and γ-ray emission, and lastly by the β or electron conversion decay which is accompanied by the delayed emission of neutrons and γ-rays. In general, 75 to 85% of the total available energy is present as fragment kinetic energy, whereas about 10% and 3 to 4% are contained in the prompt neutron and γ-ray emission processes. A fraction of about 8% of the total available energy from the whole mass rearrangement down to stable isotopes is released in the β decay and electron conversion and subsequent delayed γ-ray and neutron emission. This chapter discusses time scale in fission, the integral fission neutron energy spectrum, early neutrons, neutron multiplicities, the dependence of neutron emission on excitation energy, prompt neutron emission in the resonance region, neutron emission in ternary fission, prompt gamma emission in fission, and delayed neutron and gamma emission. 132 refs., 29 figs., 3 tabs