From Online Dictionary of Crystallography
Angle de Bragg (Fr). Bragg-Winkel (Ge). Angolo di Bragg (It). ブラッグ角度 (Ja). Ángulo de Bragg (Sp).
In Bragg's law describing the condition for a plane wave to be diffracted from a family of lattice planes, the angle θ between the wave vector of the incident plane wave, ko, and the lattice planes (see figure).