MULTIPLICITY COUNTING FROM FISSION DETECTOR SIGNALS WITH TIME DELAY EFFECTS

Year
2017
Author(s)
Lajos Nagy - Division of Subatomic an Plasma Physics, Chalmers University of Technology, Budapest University of Technology and Economics, Institute of Nuclear Techniques
Imre P´azsit - Division of Subatomic an Plasma Physics, Chalmers University of Technology
L´en´ard P´al - Centre for Energy Research, Hungarian Academy of Sciences
Abstract
In recent work, we have developed the theory of using the first three auto or joint central moments of the currents of up to three fission chambers to extract the singles, doubles and triples count rates of traditional multiplicity counting. Such a method would make it possible to determine the same item parameters (in particular the mass of the sample) as the traditional multiplicity counting with detectors in the pulse mode, without dead time problems. A restriction of the previous work was that all neutrons born in a source event (spontaneous fission) were assumed to reach the detector simultaneously, which is not fulfilled in reality. In the present work, this restriction is eliminated. It is shown how the central moments of the detector current(s) are related to the S, D and T count rates in the case when delay effects between neutrons from the same source event are taken into account. The presented formulas, and hence also the performance of the proposed method, are tested by numerical simulations.