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Towards in-situ water quantification via neutron imaging: insights from NeXT-Grenoble

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Measurement Science and Technology
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Arash Nemati at Grenoble Alpes University
Arash Nemati
Bratislav Lukić at European Synchrotron Radiation Facility
Bratislav Lukić
Alessandro Tengattini at Joseph Fourier University
Alessandro Tengattini
Matthieu Briffaut at École Centrale de Lille
Matthieu Briffaut
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Abstract and Figures

Neutron imaging has gained increasing attention in recent years. A notable domain is the in-situ study of flow and concentration of hydrogen-rich materials. This demands precise quantification of the evolving concentrations. Several implementations deviate from the ideal conditions that allow the direct applicability of the Beer–Lambert law to assess this concentration. The objective of this work is to address these deviations by applying both calibration and correction procedures to ensure and validate accurate quantitative measurements during 2D and 3D neutron imaging conducted at the cold neutron source at the NeXT instrument of the Institute Laue–Langevin, Grenoble, France. Linear attenuation coefficients and non-linear correlations have been proposed to measure the water concentration based on the sample-to-detector distance. Furthermore, the effectiveness of the black body grid correction method, introduced by Boillat et al (2018 Opt. Express 26 15769), is evaluated which accounts for spurious deviations arising from the scattering of neutrons from the sample and the surrounding environment. The applicability of the Beer–Lambert law without any data correction is found to be reasonable within limited equivalent thickness (e.g. below 4 mm of water) beyond which the correction algorithm proves highly effective in eliminating spurious effects. Notably, this correction method maintains its effectiveness even with transmissions below 1%. We examine here the impact of grid location and resolution with respect to sample heterogeneity.
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Measurement Science and Technology
Meas. Sci. Technol. 35 (2024) 075405 (18pp) https://doi.org/10.1088/1361-6501/ad3cff
Towards in-situ water quantification
via neutron imaging: insights from
NeXT-Grenoble
Arash Nemati1,∗, Bratislav Luki´
c2,6, Alessandro Tengattini3,4, Matthieu Briffaut5
and Philippe Séchet1
1Université Grenoble Alpes, LEGI, 38000 Grenoble, France
2The European Synchrotron Radiation Facility, 38043 Grenoble Cedex 9, France
3Institute Laue-Langevin, 38042 Grenoble Cedex 9, France
4Université Grenoble Alpes, 3SR, 38000 Grenoble, France
5CNRS, Centrale Lille, UMR9013-LaMcube-Laboratoire de mécanique multiphysique et multiéchelle,
Université de Lille, F-59000 Lille, France
6Department of Materials, Henry Royce Institute, The University of Manchester, Manchester, United
Kingdom
E-mail: arash.nemati@univ-grenoble-alpes.fr
Received 25 January 2024, revised 23 February 2024
Accepted for publication 10 April 2024
Published 26 April 2024
Abstract
Neutron imaging has gained increasing attention in recent years. A notable domain is the in-situ
study of ow and concentration of hydrogen-rich materials. This demands precise quantication
of the evolving concentrations. Several implementations deviate from the ideal conditions that
allow the direct applicability of the Beer–Lambert law to assess this concentration. The
objective of this work is to address these deviations by applying both calibration and correction
procedures to ensure and validate accurate quantitative measurements during 2D and 3D
neutron imaging conducted at the cold neutron source at the NeXT instrument of the Institute
Laue–Langevin, Grenoble, France. Linear attenuation coefcients and non-linear correlations
have been proposed to measure the water concentration based on the sample-to-detector
distance. Furthermore, the effectiveness of the black body grid correction method, introduced by
Boillat et al (2018 Opt. Express 26 15769), is evaluated which accounts for spurious deviations
arising from the scattering of neutrons from the sample and the surrounding environment. The
applicability of the Beer–Lambert law without any data correction is found to be reasonable
within limited equivalent thickness (e.g. below 4 mm of water) beyond which the correction
algorithm proves highly effective in eliminating spurious effects. Notably, this correction
method maintains its effectiveness even with transmissions below 1%. We examine here the
impact of grid location and resolution with respect to sample heterogeneity.
Keywords: neutron tomography, water concentration, scattering correction,
black-body (BB) correction, in-situ measurements, fast tomography
1. Introduction
Neutron imaging is a powerful non-destructive method that
has gained signicant interest in recent years. In contrast to
x-ray radiation, which interacts with the electron cloud of
∗Author to whom any correspondence should be addressed.
atoms, neutron imaging relies on the interaction with the nuc-
lei of the elements along the penetrated material thickness [1,
2]. Neutron imaging is sensitive to certain lighter elements
(e.g. hydrogen and lithium) as can distinguish between iso-
topes, while is able to deeply penetrate some high atomic num-
ber materials (e.g. gold, iron, lead) [3]. Recent advancements
have fostered time-resolved 4D tomography (3D+time), while
1 © 2024 IOP Publishing Ltd
... This limitation hindered the ability to validate and develop numerical benchmarks and to encourage future advancements in numerical modeling. In this work the calibration results performed by Nemati et al. (2024) were applied so as to extract the 3D water content in sandstone samples during constant flow rate vapor injection experiments. Consistency was observed between the overall evolving water content in the sample, as identified from the neutron tomography data, and the measured boundary condition in the experiments. ...
... It was then followed by a 3D Gaussian filter (standard deviation of 1.5 voxels) to smooth the data and mitigate noise unavoidable with the low exposure time. A more detailed description of the imaging system is available in Nemati et al. (2023Nemati et al. ( , 2024, Tengattini et al. (2020). ...
... (3)-(6) due to deviations and non-linearities in the assumptions made by the Beer-Lambert law. In a previous study (Nemati et al., 2024), the impacts of scattering and beam hardening of water were investigated at NeXT, with a specific focus on the effects of water content measurements, as deduced from calibration experiments on reference samples (phantoms). Results showed that, for water thicknesses in the range of [0, 4] mm along the beam direction, the deviation from the Beer-Lambert law is negligible, and scattering as well as beam hardening contribution can be taken into account simply by selecting an appropriate water attenuation coefficient. ...
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