EXTRACTING GATE UTILIZATION FACTORS

摘要

In the last several years a concerted effort has been made by the safeguards community to re-examine the theory and practice of neutron multiplicity counting. This has led to a renewed interest in the extraction and application of deadtime corrected net Singles, Doubles, Triples, Quads and Pents in various ways complementary to the usual approach based on event triggered multiplicity shift register time correlation analysis. If we are to invert these rates for item parameters, such as ~(240)Pu-effective mass, (α,n)/(SF,n)-ratio, and leakage multiplication, we also need ways to obtain and confirm the corresponding detector model parameters including the rate-extraction-method-specific gate utilization factors. The gate utilization factor is the fraction of correlated events of a given order on the pulse train that are counted by the finite coincidence gate. In this work we provided the expressions needed to extract gate utilization factors for signal triggered shift register time correlation analysis (MIXed) and randomly triggered inspection (RTI) rates using fast accidental sampling. These are then applied to characterization data acquired using ~(252)Cf for the LANL ENMC (Epithermal Neutron Multiplicity Counter). The extrapolated infinite gate rates obtained using different approaches are compared as a basic test of instrument non-ideal behavior and self-consistency.