Background Pulse Pile-Up in Neutron Counting Channels

An experimental study of background pulse pileup in neutron counting channels has been performed. Noutron- and gamma-produced pulses from two BF3-filled counters and one boron-lined counter were photographed for several input circuit time constants. Several measurements were made for each of ten counting channels: five commercially available circuits, three Bettis reactor source range channels, and two experimental systems. Integral bias curves taken with simulated neutron and gamma pulses were the major comparison criterion. Wide differences in performance were found, even among very similar circuits. The results indicate that small pulse pile-up in the test circuitry may greatly influence data taken with counters operating in high-background gamma fluxes. Recommendations are made for the design of circuitry with reduced pile-up.