Angular Distribution Measurement of Gamma Rays from Inelastic Neutron Scattering on Fe-56 at the nELBE Time-of-Flight Facility

Inelastic neutron scattering from 56 Fe was studied at the nELBE time-of-flight facility. The incoming neutron energy ranges from 100keV to 10MeV in the fast neutron spectrum, where high precision nuclear data are needed. A detector setup has been installed to investigate the γ-ray angular distributions. It contains five HPGe and five LaBr 3 detectors positioned at 30, 55, 90, 125 and 150 degrees relative to the beam axis. The intrinsic and the neutron induced background from the setup was subtracted by cyclical measurements with and without the natural Fe-target. Corrections for extended source efficiency and gamma-self-absorption, inside the target, were done using GEANT4 simulations.
The angular distributions measured with the HPGe detectors are compared with earlier data. High neutron energy resolution up to a few keV was obtained with the LaBr 3 detectors due to their much better time resolution.