Nuclear data uncertainty in iterative neutron spectrum unfolding

We developed an algorithm for propagating the uncertainty of dosimetry cross sections to that of the neutron spectrum obtained through multiple-foil activation and unfolding process. The algorithm derives the uncertainty of the solution spectrum as the standard deviation of a set of solution spectra...

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Bibliographic Details
Published inJournal of nuclear science and technology Vol. 59; no. 7; pp. 907 - 914
Main Authors Aoki, Katsumi, Kin, Tadahiro, Otuka, Naohiko
Format Journal Article
LanguageEnglish
Published Tokyo Taylor & Francis 03.07.2022
Taylor & Francis Ltd
Subjects
accelerator-based neutron source
activation method
Algorithms
covariance
Covariance matrix
Dosimeters
dosimetry
Foils
Neutron spectrum
Nuclear cross sections
Uncertainty
unfolded spectrum uncertainty
unfolding
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Summary:We developed an algorithm for propagating the uncertainty of dosimetry cross sections to that of the neutron spectrum obtained through multiple-foil activation and unfolding process. The algorithm derives the uncertainty of the solution spectrum as the standard deviation of a set of solution spectra obtained by unfolding with numerous sets of dosimetry cross sections, which are randomly generated from the evaluated cross sections and their covariances in a data library. We simulated a multiple-foil activation experiment in a C(d,n) neutron field by PHITS code for some dosimetry reactions to test the algorithm. The GRAVEL code analyzed production amounts to unfold neutron spectrum and then our new algorithm derived the uncertainties of the resultant neutron spectrum originated in the nuclear data uncertainty. Further, we found the uncertainty of the solution spectrum becomes smaller if we ignore the off-diagonal elements of the covariance matrices of the dosimetry cross sections.
ISSN:0022-3131
1881-1248
DOI:10.1080/00223131.2021.2018370