Modeling of Damage along the Tracks of Swift Heavy Ions in Polyethylene

Abstract

The results of atomic-level modeling of damage formation along the whole trajectory of swift heavy ions, stopping in the electronic energy loss mode in polyethylene are presented. Theoretical models could significantly improve the understanding of track formation in polymers, but their main disadvantage is an insufficient level of detail. In this paper, this problem is solved by using a multiscale hybrid approach: the Monte–Carlo TREKIS program describes the excitation of an electronic system of a target; the reactive molecular dynamics of the response of an atomic system to an ion-induced perturbation within the framework of the LAMMPS program allows to trace the damage up to the time of complete cooling of the track. Detailed tracing of the coupled electronic and atomic kinetics has shown that the damage maxima are spatially separated by at least 10 μm from the maxima of energy released by the ions. The differences occur due to the dependence of the initial spectra of electrons generated near the ion trajectory on the ion energy. The effects demonstrated should be the same for all polymers and may be critical for the effective operation of devices and detectors containing thin polymer films irradiated with swift heavy ions.