Computational Investigation and Experimental Verification of Multiplicity Counting from the Continuous Signals of Fission Chambers

In a series of previous publications, we suggested an alternative method to the pulse-counting based multiplicity counting technique for the characterisation of special nuclear materialscollision number expansion. The new method uses the continuous signals of fission chambers, and the multiplicity rates, i.e. the singles, doubles and triples rates are extracted from the auto- and cross-covariances of one or more fission chambers. Until recently only the theory of the method was elaborated. The purpose of the work described in this report was to verify the method and investigate its performance and applicability through detailed simulations as well as with a dedicated experiment. Numerical simulations of the method were performed by a code specially developed for this study, and pilot measurements were performed at the critical assembly KUCA of the Institute for Integrated Radiation and Nuclear Science, Kyoto University (KURNS). This report gives an account of both the work performed and the results of the study