Previous theoretical results on the inelastic scattering of neutrons in ideal crystals are reviewed. Restrictive conditions imposed by crystal interference on inelastic scattering are discussed. It is found that if the velocity of the incident neutrons is smaller than the sound velocity in the crystal, neutrons from a monochromatic, well-defined beam are scattered by inelastic processes into sharply limited areas. On the other hand, inelastic scattering of faster neutrons should give rise to diffuse spots similar to those observed in inelastic scattering of x-rays.

• Received 4 March 1942

DOI:https://doi.org/10.1103/PhysRev.62.37