Optimizing the primary knock-on atom for simulating particle radiation-induced structural damage in Zr-based metals

Abstract

Molecular dynamics (MD) can simulate the production of radiation-induced point defects in materials. However, the initial conditions of one “hypothetical” primary knock-on atom (PKA) which starts the MD simulation usually are simplified. In the present work, we aim to obtain the optimized initial conditions of PKA by using the Geant4 software which can simulate the passage of particles through matter. We find that the spectra of kinetic energies of PKAs are similar with each other among pure Zr, Zr2Cu, and Zr2Ni. This indicates that adopting simplified structural models can approximate the atomic-level structural damage in some corresponding served nuclear materials, such as Zr-based and Fe-based alloys. In addition, it is revealed that the moving directions of PKAs strongly relate to the kinetic energies of neutrons, and the corresponding preferred scattering angles of PKAs could be estimated. These findings are helpful for optimizing the initial conditions of MD simulation, and extend our understanding on simulating structural damage in nuclear materials accordingly.