Darwin plateau width w_D = 2χ_H/sin(2θ_B); Pendellösung Λ_p = λ·cos θ_B/χ_H

Sympy-exact symbolic witness of the Darwin-Prins dynamical-diffraction width, period, and integrated reflectivity. Setup: χ_H, θ_B, λ sp-symbols positive. Darwin plateau angular full-width: w_D = 2·χ_H/sin(2·θ_B); sympy canonical…