What is it about?
Extinction effects are the phenomenon where Bragg diffraction intensity is reduced and, consequently, transmission is increased, relative to the predictions of an ideal polycrystalline model. We carried out complementary time-of-flight neutron powder diffraction and transmission measurements to characterize four beryllium samples and assess extinction effects. The measured transmission data could be explained with a lattice-plane-dependent extinction model, while the diffraction measurements rule out texture as the cause of the discrepancies between the calculated and observed cross-sections. Our results demonstrate that neutron transmission measurements are particularly sensitive to extinction effects.
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Why is it important?
Extinction effects have been widely explored in X-ray and neutron diffraction for decades. However, their influence on neutron transmission, especially in the context of cross-section measurements, has received less emphasis. Here, we show that transmission measurements are particularly sensitive to extinction. This insight may shed light on extinction effects in diverse materials and has important implications for neutron transmission measurements including wavelength-resolved imaging and accurate cross-section measurements.
Perspectives
Extinction models, such as those by Sabine and Becker & Coppens, are rooted in Darwin's phenomenological equations. A promising direction for advancing this field is the single-to-polycrystal approach, which offers a novel pathway for exploring extinction effects in polycrystalline materials.
Shuqi Xu
Lunds Universitet
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This page is a summary of: Impact of extinction effects on neutron transmission in solid beryllium metal, Journal of Applied Crystallography, October 2025, International Union of Crystallography,
DOI: 10.1107/s1600576725007939.
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