Neutron focusing effects in perfect-crystal systems

Abstract

Four different focusing effects in two-crystal systems are discussed. (i) Focusing of monochromatic radiation at the back face, (ii) a geometric focus of polychromatic radiation, (iii) pure-wavefield foci due to lenses between the crystal plates and (iv) effective-mass enhanced focusing inside crystals due to the action of inhomogeneous external forces. We present some new experimental results on these foci and point out their relevance for the development of novel neutron interferometry systems.