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Improving FNMC for the matrix effect of spherical shell plutonium samples

Suxia Hou and Jijun Luo
From the journal Kerntechnik


The fissile mass deduced from fast neutron multiplicity counting (FNMC) measurement is underestimated if the matrix self-absorption effect of the radioactive source is not taken into account. Based on the analysis of FNMC equations, a set of FNMC system was built to simulate and study the mass attribute of the hollow sphere (spherical shell) plutonium under different shapes and different masses conditions. Geant4 simulation shows that an appropriate parameter correction successfully removes the bias because of the matrix effect. Consequently, the self-multiplication factor, α coefficient and scattering crosstalk of the simulation result were corrected after analyzing the detection efficiency and multiplicity counting rate, and the corresponding polynomial fitting equation was obtained. The corrected mass deviation of samples was less than ±1% in this interval. The results show that the combination of the FNMC and parameter correction can accurately measure the sample mass attribute, which provides a new method for solving similar problems.

Corresponding author: Suxia Hou, Shaanxi Engineering Research Center of Controllable Neutron Source, School of Science, Xijing University, Xi’an, Shaanxi 710123, P. R. China, E-mail:

Funding source: National Nature Science Fund of China

Award Identifier / Grant number: 51309228

Funding source: Postdoctoral Science Foundation of China

Award Identifier / Grant number: 2013M3M542459

Funding source: Shaanxi Technology Committee Natural Science Basic Research Project

Award Identifier / Grant number: 2016JM6026


The authors are grateful to the precious comments made by anonymous reviewers. We would like to acknowledge the technical supports from professor Quanhu Zhang (Xi’an Research Institute of Hi-Tech). The authors also thank the technical supports for experimental data measurement from China Institute of Atomic Energy.

  1. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: This study was financially supported by the National Nature Science Fund of China Grants Agreement Number 51309228, the Postdoctoral Science Foundation of China (No. 2013M542459), and Shaanxi Technology Committee Natural Science Basic Research Project (No. 2016JM6026).

  3. Conflict of interest statement: The authors declare no conflicts of interest regarding this article.


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Received: 2021-03-15
Published Online: 2022-05-17
Published in Print: 2022-06-27

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