A High-Performance Neutron Time Correlation Counter

A new, high-performance neutron time correlation, or coincidence, counter has been developed for the measurement of nuclear materials. This detector is an improvement over the high-level neutron coincidence counter that was used previously in that it has better counting rate capability, electronic stability, noise resistance, uniform counting zone, and portability. The system uses ³He gas tubes coupled to the shift register coincidence electronics through a new hybrid charge-sensitive preamplifier/discriminator. Counting rates of 1.3 MHz have been obtained and a counting stability of 0.002% has been measured. The system has been applied to the assay of plutonium content in metal, PuO₂, and PuF₄, as well as in uranium-plutonium mixtures.