Combined Bonner sphere and threshold fission detector spectrometer

A combined spectrometer is proposed consisting of Bonner sphere and threshold detectors, suitable for in-pile neutron spectra measurement. The utilization of the Bonner sphere resulted in better resolution of the spectrometer in the region of neutron energy less than 1 MeV, a reduced oscillation of calculations in the resonance neutron region, and in an increased sensitivity in the entire intermediate neutron region. The combination of the Bonner sphere 7.62 cm in diameter with 235U in the centre, a polyethylene sphere 10 cm in diameter wrapped in boron of 1.4 g/cm2 in density with 235U in the centre, and of 232Th, 237Np and 235U fission track detectors in cadmium and without cadmium is considered to be the most suitable and general purpose system for long-term study of neutron spectra. (Z.M.)