Absolute determination of neutron detection efficiencies of NE213 detectors using a 252Cf source in time-of-flight measurements

Neutron detection efficiencies of NE213 scintillation detectors were determined by comparison of the measured neutron time-of-flight spectrum of a 252Cf source deposited in a parallel-plate, low-mass ionization chamber with its reference neutron energy distribution. Measurement conditions and parameters were systematically varied to study their influence on the efficiencies obtained. The efficiencies derived from the measurement were compared with well-established efficiencies of the detectors used. These efficiencies were calculated with a Monte Carlo code and corrected after comparison with a proton recoil telescope in neutron fluence measurements. Details of the measurement and the data analysis including the corrections needed are discussed.