Convolutional discrete Fourier transform method for calculating thermal neutron cross section in liquids

Being exact at both short- and long-time limits, the Gaussian approximation is widely used to calculate neutron incoherent inelastic scattering functions in liquids. However, to overcome a few numerical difficulties, extra physical approximations are often employed to ease the evaluation. In this wo...

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Bibliographic Details
Published inJournal of computational physics Vol. 466; p. 111382
Main Authors Du, Rong, Cai, Xiao-Xiao
Format Journal Article
LanguageEnglish
Published Cambridge Elsevier Science Ltd 01.10.2022
Subjects
Computational physics
Fast Fourier transformations
Inelastic scattering
Light water
Liquids
Mathematical analysis
Nuclear cross sections
Numerical methods
Scattering functions
Thermal neutrons
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Summary:Being exact at both short- and long-time limits, the Gaussian approximation is widely used to calculate neutron incoherent inelastic scattering functions in liquids. However, to overcome a few numerical difficulties, extra physical approximations are often employed to ease the evaluation. In this work, a new numerical method, called convolutional discrete Fourier transform, is proposed to perform Fourier transform of exp⁡[−f(t)]. We have applied this method to compute the differential cross sections of light water up to 10 eV. The obtained results, thoroughly benchmarked against experimental data, showed a much higher dynamic range than conventional fast Fourier transform. The calculated integral cross sections agree closely with the light water data in the state-of-the-art nuclear data library. It is in evidence that this numerical method can be used in the place of the extra physical approximations.
ISSN:0021-9991
1090-2716
DOI:10.1016/j.jcp.2022.111382