GAMMA-RAY DIFFRACTOMETRY INVESTIGATION OF DISLOCATION DENSITY IN MASSIVE QUARTZ CRYSTALS

The investigation of dislocation density in massive quartz crystals wa s carried out with the help of gamma-ray diffractometer. High monochro matic gamma-ray radiation from Au-198 source activated by nuclear reac tor neutrons (E = 412 keV, lambda = 0.03 Angstrom; Delta lambda/lambda less than or equal to 10(-6)) was used. The beam cross section was 0. 1 x 10 mm(2) with angular divergence of 9 angular seconds. Statistical dynamic diffraction theory was used for dislocation density calculati on from experimental results. The comparison data were obtained for se veral quartz crystals by determining dislocation density by various me ans, i.e. by using gamma-ray diffractometer, X-ray topography and by c alculation of etching channels in AT-cut plates for the same crystals. Good agreement of the results obtained by these methods shows perspec tivity of gamma-ray diffraciometry method for non-destructive dislocat ion concentration control in massive quartz crystals.