Small-angle neutron scattering study of radiation defects in synthetic quartz

The superatomic structure of synthetic quartz single crystals with dislocation densities p = 54 and 570 cm(-2) was studied in the initial state and after irradiation with fast neutrons with energies E-n > 0.1 MeV in a WWRM reactor (St. Petersburg Nuclear Physics Institute) in the fluence range F = 0.2 x 10(17)-5.0 x 10(18) neutrons/cm(2). Weak irradiation with F = 0.2 x 10(17) neutrons/cm(2) causes only slight structural changes, whereas appreciable generation of defects with radii of gyration r(g) similar to 1-2 nm and R-G similar to 40-50 nm occurs at F = 7.7 x 10(17)-5.0 x 10(18) neutrons/cm(2). As the fluence increases further, the number and volume fraction of point defects, as well as extended (channels similar to 2 nm in radius) and globular (amorphous phase nuclei) defects, increase.