A fast neutron spectrometer with fast coincidence technique in proportional counters

Abstract The preliminary results on a fast neutron spectrometer, in which a new method of electronic collimation is employed, are reported. The principle and typical performance of the electronic collimation for alpha particles are first reviewed, and in the following part, the performance of the spectrometer is described for mono-energetic neutrons of 0.6–1.5 MeV. The dispensation with a conventional collimator in a neutron spectrometer, by introducing an electronic collimation, was expected to reduce the background due to the collimator material, but a background continuum was still observed in the present method. However, this continuum was removed by combining the present method with a rise time discrimination method which has been described previously.