COMPUTER-SIMULATION OF CASCADE DAMAGE IN METALS

Using the time-evolution binary collision lattice computer simulation code DYACOCT, the collisional phase of cascade damage in metals produced by a high-energy PKA has been investigated. The calculated subcascade energies of Cu, Ag and Au metals are about 5 keV, 10 keV, and 10 keV, respectively. These calculated subcascade energies are in good agreement with experimental results for Ag and Au metals, but not for a Cu target. It is found that the focussing collision plays an important role in the structure of individual subcascades. About 10% of produced recoils experience at least one focussing collision, and the average migration length due to focussing collision is about 0.8 nm. The collision cascade is found to have a fractal structure and the collision cascades in Cu, Ag and Au metals produced by high PKA energy (E > 20 keV) have the same fractal structures.