The Study of Second-order Contamination Caused by Multiple Diffraction in a Ge(113) Monochromator

Abstract

Neutron intensities of the main wavelength (λ), the second-order (λ/2) and the third-order (λ/3) components in the Ge(113) reflecJed reactor beam were measured by the time-of-flight method for wavelength λ from 1.6 up to 2.41 Å. 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 secondorder 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.