Simulation study of collision cascade of NaI crystal

Abstract

The collision cascade between the primary knock-on atom and the crystal lattice atoms is an important physical process of the radiation damage of NaI crystals. The study of the collision cascades of NaI crystals is significant for their radiation performance evaluation and improvement research. In this paper, the collision cascades of NaI crystals are studied by means of molecular dynamics simulation, aiming at providing a theoretical basis for the radiation damage research of NaI crystals. First, the physical model and the numerical simulation method of the collision cascades of NaI crystals are introduced. Second, the threshold displacement energies of NaI crystals were calculated by means of molecular dynamics simulation, and their influencing factors were analyzed. The calculation results show that, when the material temperature is 300 K, the maximums of the threshold displacement energies of the recoiled Na and I atoms are 49.5 eV and 80.6 eV respectively. At last, the collision cascade processes of NaI crystals were simulated and analyzed, and the variation laws between the number of the displaced atoms, the atom spatial distribution in the NaI crystal and the time were calculated.