Many-Particle Cooperative Scattering of X-Rays in the Two-Crystal Spectrometer

It has been emphasized previously that low-angle x-ray scattering pattenns should theoretically exhibit a relatively high, extremely narrow central maximunn because the entire irradiated sample will scatter coherertly in the same phase at scattering angles very close to zero. This should be observed in some cases where the x-ray beam has been collimated by means of a plane, nearly perfect crystal. Such a case arises when the two-crystal spectrometer is used in parallel position for the study of low-angle x-ray-diffraction patterns. (W.D.M)