Measurement of the inelastic neutron scattering cross section of 56Fe

The (n,n'γ) cross section σinel to the 1st excited state of 56Fe has been measured at the neutron time-of-flight facility nELBE of the Forschungzentrum Dresden-Rossendorf. The nELBE neutron source delivers neutrons with energies from 100 keV up to 10 MeV. By means of a ''double-time-of-flight'' setup σinel of the 1st excited state could be measured over the whole energy range without knowledge about cross sections of higher-lying levels. Plastic scintillators were used to detect the inelastically scattered neutron and BaF2 detectors to detect the correlated γ-ray. The time of detection of the γ-ray defines the time-of-flight of the incoming neutron. The time difference between γ- and neutron-detection gives the energy of the scattered neutron. By this method the excitation of the 1st level can be identified independently from the emitted γ-ray energy.