Effect of double false pulses in calibrated neutron coincidence collar during measuring time-correlated neutrons from PuBe neutron sources

Characterizations of double pulsing in neutron multiplicity and coincidence counting systems

“…Recent results have shown that contrary to the commonly-held assumption that a pre-delay is effective in eliminating the effect of double pulsing in shift register-based time correlation analysis, double pulsing still affects the measured coincidence rates [3]. This research also showed that double-pulsing yields a distinctive signature in the Rossi-alpha distribution (RAD),…”

“…As the design of 3 He counters can have an effect on the intensity and magnitude of imperfections such as double pulsing, the starting point of these simulations is as accurate and detailed a description of an actual counter as possible. Neutron coincidence and multiplicity counters are typically a composite of many 3 He tubes, with several tubes electronically bundled to the same preamplifier. Note that preamplifiers refer here to a signal processing unit composed of signal shaping and identification and logical pulse generation.…”

“…To simulate double pulsing and dead time, the neutron-capture location (i.e. in which 3 He tube the capture occurred) along with the time of a neutron detection is tracked, so it is possible to add these electronic imperfections to the simulations on a preamplifier level.…”

“…While previous work [3] focused on the effect that double pulsing has on singles and doubles rates and noticed a signature of double pulsing in the RAD, current research characterizes the quantitative effects double pulsing has on both the RAD and the correlated rates, including higher order multiplicities not addressed in [3], so as to be able to recognize and correct for it.…”

“…Assay of special nuclear material (SNM) for international nuclear safeguards typically relies on nondestructive assay techniques such as neutron coincidence and multiplicity counting. This is most often done using 3 He-based detector systems and shift register analysis to extract and quantify neutron correlations [1,2]. These techniques suffer from detector and electronics effects such as dead time or can be affected by detector and electronics artifacts like double pulsing.…”