Angular distributions and anisotropy of fission fragments from neutron-induced fission of 239Pu, 237Np, and natPb in energy range 1–200 MeV

This work summarizes some results of a series of experiments aimed at the investigation of energy dependence of anisotropy of fission fragments (FFs) in (n , f ) reactions for neutron energies from low to intermediate. Angular distributions of FFs from the neutron-induced fission of 239 Pu, 237 Np, and nat Pb have been measured in the energy range 1–200 MeV at the neutron TOF spectrometer GNEIS based on the spallation neutron source at 1 GeV proton synchrocyclotron of the Petersburg Nuclear Physics Institute (Gatchina, Russia). The anisotropies of FFs deduced from the measured angular distributions are presented. In the neutron energy range above 20 MeV the results have been obtained for the first time in our works. The experimental data for FF anisotropy in 237 Np(n , f ) are compared with calculations based on adapted TALYS software.