ANGULAR AMPLIFICATION IN NEUTRON OR X-RAY DYNAMICAL DIFFRACTION BY PERFECT CRYSTALS

A theoretical analysis of the properties of the dispersion surface related to the dynamical theory of diffraction of neutron or X-rays by perfect crystals leads to the prediction of an angular amplification effect when an asymmetric cut of the crystal is performed. Contrary to the well-known angular amplification effect occurring inside the crystal and disappearing at the outer surface in the symmetrical Laue case, the angular amplification discussed in the present paper concerns the beam emerging from the crystal, so that several angular amplifiers in cascade can be used. A possible application of this effect is discussed.