An X-ray topographic study of large crystals for a bent-crystal gamma diffractometer

Abstract

We have developed several conventional techniques of X-ray diffraction topography to the scale and resolution necessary for the selection of crystals and the non-destructive analysis of bend profiles of γ-spectrometers. It is shown that the shape of the Bragg planes in such a spectrometer can be mapped with sufficient precision that the spectrometer performance can be analysed in situ. As a result of applying these techniques we have been able to select and manipulate silicon crystals to the point where they are just better than quartz in both spectrometer efficiency and energy resolution. Further improvements should be possible since the intrinsic crystal perfection is still about 10 times better than the perfection of the cylindrical bend profile achieved in practice.