Characterization of neutron-induced defects in metals by positron annihilation spectroscopy

The development of radiation-tolerant materials is crucial for the next generation of nuclear fission and fusion reactors. Recent molecular-dynamic simulations predict that nanostructured materials may demonstrate radiation resistance due to effective defect annealing at the grain boundaries. In this work, we investigate and compare neutron-induced defects in copper in the single crystal and ceramic forms. Samples were irradiated by neutrons inside a nuclear reactor and characterized by positron lifetime spectroscopy and Doppler broadening measurements. The study reveals the effect of grain boundaries on defect formation and annealing.