Refraction Shift of Bragg Reflection of Neutrons

A refraction shift of the asymmetric Bragg reflection of thermal neutrons is observed. Germanium crystals are used to demonstrate this in an invariant geometry while the index of refraction is changed. Two values of the index-of-refraction jump at one crystal surface are created by simultaneous reflection of neutrons with fractional wavelengths, by immersing the crystal partially a liquid (heavy water), and by creating a jump of magnetic induction at the crystal surface. The observed Bragg reflection shifts reach values of 40 to 50 s of arc. The presented method can be used for measuring the indices of refraction. [Russian Text Ignored]