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

A theoretical analysis of the properties of the dispersion surface rel ated to the dynamical theory of diffraction of neutron or X-rays by pe rfect crystals leads to the prediction of an angular amplification eff ect when an asymmetric cut of the crystal is performed. Contrary to th e well-known angular amplification effect occurring inside the crystal and disappearing at the outer surface in the symmetrical Laue case, t he angular amplification discussed in the present paper concerns the b eam emerging from the crystal, so that several angular amplifiers in c ascade can be used. A possible application of this effect is discussed .