The study of second-order contamination caused by multiple diffraction in a Ge(113) monochromator

Abstract

Abstract Neutron intensities of the main wavelength (λ), the second-order (λ/2) and the third-order (λ/3) components in the Ge(113) reflected reactor beam were measured by the time-of-flight method for wavelength λ from 1.6 up to 2.41 A. The measurements have been made as a function of the azimuthal angle ψ of a Ge (113) monochromator rotation around the scattering vector. It is shown that the second-order component caused by multiple diffraction is present over a wide interval of angle ψ and its maximum value increases with wavelength. The second-order contamination can be avoided or decreased by the proper orientation of the monochromator.