Atomistic simulation of track formation by energetic recoils in zircon

Abstract

We have performed classical molecular dynamics simulations of fission trackformation in zircon. We simulated the passage of a swift heavy ion throughcrystalline zircon using cylindrical thermal spikes with energy deposition (dE/dx) of 2.5–12.8 keV nm − 1 and a radius of3 nm. At a low dE/dx of 2.55 keV nm − 1, the structural damage recovered almost completely and a damage track was not produced. At highervalues of dE/dx, tracks were observed and the radius of the track increased with increasingdE/dx. Our structural analysis shows amorphization in the core of the trackand phase separation into Si-rich regions near the center of the track andZr-rich regions near the periphery. These simulations establish a thresholddE/dx for fission track formation in zircon that is relevant to thermochronology and nuclear wasteimmobilization.