Evaluation of the Prompt Fission Neutron Spectrum of Thermal-neutron Induced Fission in U-235

A new evaluation of the prompt fission neutron spectra (PFNS) for the neutron-induced fission of the U-235 nucleus is presented. By using differential data as “shape data” good consistency was achieved between selected sets of differential data. A fit of dif- ferential PFNS data with the generalised least-squares method using the GANDR code allowed the estimation of the uncertainties and correlations. All experimental data were consistently fitted in a model independent way giving a PFNS average energy of2.000 MeV with an estimated 9 keV uncertainty.