International
Tables for
Crystallography
Volume H
Powder diffraction
Edited by C. J. Gilmore, J. A. Kaduk and H. Schenk

International Tables for Crystallography (2018). Vol. H, ch. 2.3, p. 69

Section 2.3.2.4. Neutron attenuation

C. J. Howarda* and E. H. Kisia

aSchool of Engineering, University of Newcastle, Callaghan, NSW 2308, Australia
Correspondence e-mail:  chris.howard@newcastle.edu.au

2.3.2.4. Neutron attenuation

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Neutron beams are attenuated by coherent scattering, incoherent scattering and true absorption. The cross sections for all these processes are included in the tables cited above. For powder diffraction, the coherent scattering is usually small because it takes place only in that small fraction of crystallites correctly oriented for Bragg reflection; the other processes, however, take place throughout the sample.

If a particular scattering entity i with scattering cross sections (σi)inc and (σi)abs is present at a number density Ni, then the contribution it makes to the linear attenuation coefficient μ is [{\mu }_{i}={N}_{i}[{{(\sigma }_{i})}_{\rm inc}+{{(\sigma }_{i})}_{\rm abs}]]. If the mass is Mi, then the density is simply [{\rho }_{i}={N}_{i}{M}_{i}], so we have the means to evaluate the mass absorption coefficient [(\mu /\rho)_{i}]. The calculation of absorption for elements, compounds and mixtures commonly proceeds by the manipulation of mass absorption coefficients, in the same manner as is employed for X-rays (see Section 2.4.2 in Kisi & Howard, 2008[link]).

References

Kisi, E. H. & Howard, C. J. (2008). Applications of Neutron Powder Diffraction. Oxford University Press.Google Scholar








































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