The scission neutron spectrum of252CF (SF)

Abstract

The scission neutron spectrum was obtained as a difference between the integral experimental fission neutron spectrum evaluated by Mannhart based on measurements in the laboratory reference system from several authors in the different neutron energy ranges, and the laboratory fission neutron spectrum stemming only from those neutrons which are evaporated from the fully accelerated fission fragments. The scission neutron spectrum was represented by a Weisskopf evaporation spectrumps(ɛ l )=P0/(Ts)2·ɛl·exp(−ɛl/Ts). A least squares fit gave for the fraction of scission neutrons with respect to all fission neutrons a value ofp0=(0.011±0.003) and for the pseudo scission neutron temperature a value ofTs=(0.20±0.03) MeV. The low pseudo temperature is compatible with a cold nuclear matter of the prescission configuration. The low energy of the scission neutrons indicates that they come from a slowly moving source. The width of the distribution suggests that the source is small: radius of about 5 fm. This information conforms with the idea of satellite droplets which are formed when the neck snaps.