International
Tables for Crystallography Volume C Mathematical, physical and chemical tables Edited by E. Prince © International Union of Crystallography 2006 
International Tables for Crystallography (2006). Vol. C, ch. 7.4, p. 656
Figure 7.4.2.3
B. T. M. Willis^{d}


Figure 7.4.2.3
Scattering surfaces for onephonon scattering of neutrons: (a) for neutrons faster than sound (β < 1); (b) for neutrons slower than sound (β > 1). The scattering surface for Xrays is the Ewald sphere. P_{0}, P_{1}, etc. are different positions of the reciprocallattice point with respect to the Ewald sphere, and the scattering surfaces are numbered to correspond with the appropriate position of P. 