Calculation of prompt neutron energy spectrum in laboratory system from spontaneous fission of Cf-252

In this work, we discuss the influence of the different forms of prompt fission neutron energy spectrums in the fission fragment center of mass system to the laboratory spectrum of neutrons in spontaneous fission of Cf-252. We show that the Le Couteur spectrum which takes into account multiple neutron emission of neutron emission of neutrons in the center of mass system well describes the observed neutron energy spectrum when transformed to the laboratory system. The Le Couteur in laboratory spectrum, in addition to Watt spectrum, can be used for the representation of observed prompt neutron spectrum of Cf-252 spontaneous fission.