Neutron Laue diffraction in a weakly deformed crystal at the Bragg angles close to $\pi/2$

An essential magnification of an external force acting on a diffracting neutron for the Bragg angles $\theta_B$ close to the right one is observed. Any external action (caused by either crystal deformation or external force affected the neutron) results in a bend of so called "Kato trajectories" inside the crystal and, for the case of finite crystal, gives a considerable variation of the intensities of both diffracted neutron beams (direct and reflected). It is shown that the magnification factor is proportional to $\tan^2(\theta_B)$ and can reach $~(10^2\text{--}10^3)$ for Bragg angles sufficiently close to 90$^\circ$.