Characterization of a neutron generator for the JET monitoring system calibration with NE-213 sp ectrometer

Content: The second experimental deuterium-tritium (DT2) campaign is planned at JET in 2019. Acalibration of the JET neutron emission monitoring system, consisting of fission chambers (KN1) and of an activation system (KN2), will be carried out with a compact deuterium-tritium neutron generator (NG) with suitable intensity (5x10 8 n/s). The accuracy goal for this calibration is <10% uncertainty at 14 MeV neutron energy. To achieve this goal, the compact NG was intensively examined at the National Physical Laboratory (NPL) Teddington and neutron emission spectra measured at different angles with respect to the NG axis. The examination was done utilizing diamond diodes, long counters, silicon diodes, foil activation techniques, and a NE-213 scintillator spectrometer. In parallel, a MCNP model of the NG is developed which is checked and validated by the results of the neutron spectra measurements. This MCNP model will play an essential role in the JET neutron monitor calibration.Here we report on the measurement of fast neutron spectra emitted from the compact NG recorded with a NE-213 scintillator based neutron spectrometer. The NE-213 scintillator was placed at several angles with respect to the NG axis covering a full circle with a radius of 146 cm. The measurement provides data for comparison with the MCNP model of the NG, in particular the position of the DT neutron peak in the neutron spectrum and a possible DD neutron contribution.