Calibration of a neutron spectrometer in the energy range 144 keV to 14.8 MeV with ISO energies

For calibration purposes measurements were performed with the neutron spectrometer system ROSPEC (gas proportional counters) and SSS (plastic scintillation detector) at ISO energies from 144 keV to 14.8 MeV. The spectrometer ROSPEC consists of four spherical proportional counters filled at different pressures to cover the complete energy range from 50 keV to 4,5 MeV. The SSS extends the energy range from 4 MeV to 15 MeV. The experimental data prove that both instruments are able to reproduce the nominal neutron energies within an accuracy of less than 8 per cent. The fluence measurements show in the energy range from 50 keV to 2,5 MeV a systematic overestimation of approx. 6 per cent of the absolute neutron fluences. Between 4,2 MeV and 14 MeV these systematic derivations are below 8 per cent and above 14 MeV those deviations are completely within the statistical error of less than 3 per cent.