Interstitial clustering in cascades in fast-neutron-irradiated aluminium investigated by diffuse X-ray scattering

Abstract We measure diffuse X-ray scattering close to Bragg reflections in aluminium single crystals after irradiation with fast-neutrons at 4.6 K. Detailed evaluation of the data demonstrates that interstitials are located in cascades (radius rK = 50 A). Within a cascade the institials form small clusters. The average number of three interstitials per cluster is independent of dosage up to 2.4 × 1018 n/cm2. During annealing the small clusters grow and finally form interstitial loops. For this growth long-range migration of the interstitials out of their cascade is observed.