Measurements are made with a pulsed neutron source using the time-of-flight method to determine the neutron energy. Neutrons are produced by a particle beam on a heavy material target.
The detection of reaction products (neutrons, gammas, fission fragments) is done by specific detectors optimized to operate in presence of neutrons.
These time-of-flight facilities are complementary. The resolution of GELINA is excellent while the instantaneous flux at CERN is extremely intense, which is an advantage for measurements with radioactive isotopes. A second beam line (20 m) is operational since 2014 at CERN.
The pulsed source of particles produces neutrons of various energies at a given time. At a distance of typically 10 to 200 m the neutron beam interacts with the sample under study. The reaction product is detected by a suitable detector and the detection time determines the neutron flight time and therefore its incident energy.
Les détecteurs typiquement utillisés sont