Complete neutron-multiplicity distributions in fast-neutron-induced fission
B. Fraïsse, G. Bélier, V. Méot, L. Gaudefroy, A. Francheteau, O. Roig
Abstract
The average number of neutrons emitted in neutron-induced nuclear fission has been measured for major actinides from thermal to relativistic incident energy ranges. On the other hand, the complete probability distributions could not be reconstructed from experimental data beyond a few MeV because the unfolding of the neutron-counter response is an ill-conditioned inverse problem. In order to obtain the complete neutron-multiplicity distributions without simplifying assumption on their shapes, this paper submits a robust Tikhonov-inspired regularization procedure. A revaluation, with this method, of the only available dataset, provides precise neutron-multiplicity distributions for uranium-235 and plutonium-239 up to 12 MeV. Their exact shapes are exploited to extract, for the first time from experimental data, the second-chance fission partial probability.