The influence of multiple Bragg scattering in γ-ray diffractometry

The occurrence of multiple Bragg scattering in a copper single-crystal was investigated using a well collimated γ-ray beam of wavelength 0.03 Å. The radius of the corresponding Ewald sphere is 2π/λ = 208 Å−1. With 2 20 in reflecting position multiple scattering can be avoided in principle by rotating the sample about 5° around the scattering vector. There is a possibility that multiple scattering will affect the γ-ray measurements only if the mosaic spread of the sample is larger than the smallest Bragg angle obtainable. The reflectivity of even the strongest reflections from a copper crystal of 25′ mosaic spread and thickness T = 1 cm, however, is only of the order of 5% with respect to 0.03 Å γ-radiation and therefore the influence of multiple scattering on the shape of the measured rocking curve is negligible.