An event-triggered coincidence algorithm for fast-neutron multiplicity assay corrected for cross-talk and photon breakthrough

Sarwar, R. and Astromskas, V. and Zimmerman, C.H. and Nutter, G. and Simone, A.T. and Croft, S. and Joyce, M.J. (2018) An event-triggered coincidence algorithm for fast-neutron multiplicity assay corrected for cross-talk and photon breakthrough. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 903. pp. 152-161. ISSN 0168-9002

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Abstract

A model quantifying detector cross-talk and the misidentification of events in fast neutron coincidence distributions is described. This is demonstrated for two experimental arrangements comprising rings of 8 and 15 organic liquid scintillation detectors. Correction terms developed as part of this model are tested with  252Cf and a relationship is developed between the  235U enrichment of U 3 O8 and the order of correlated, fast neutron multiplets induced by an americium-lithium source. The model is also supported by Geant4 simulations. The results suggest that a typical assay, for experimental arrangements that are similar to the examples investigated in this research, will exhibit cross-talk for less than 1% of all detected fast neutrons but, if not accounted for, this can bias the numerical analysis by a margin of 10% and 35% in second- and third-order coincidences (i.e. couplet and triplet counts), respectively. Further, for the case of  252Cf, it is shown that a relatively low proportion of 4% breakthrough by γ rays (that is, photons misidentified as neutrons by the pulse-shape discrimination process) can lead to an erroneous increase of 20% in total neutron counts in the assay of a mixed-field, in this case of  252Cf. These findings will help direct the developments needed to enable organic scintillation detectors with pulse shape discriminators to be applied reliably to nuclear safeguards and non-proliferation verification tasks.

Item Type:
Journal Article
Journal or Publication Title:
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Additional Information:
This is the author’s version of a work that was accepted for publication in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 903, 2018 DOI: 10.1016/j.nima.2018.06.056
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/3100/3106
Subjects:
ID Code:
126227
Deposited By:
Deposited On:
02 Jul 2018 09:02
Refereed?:
Yes
Published?:
Published
Last Modified:
25 Sep 2020 03:47