THEORY FOR LATENT PARTICLE TRACKS IN POLYMERS

An atomistic model is developed which accounts for the rate of accumulation of ion-induced radiation damage in the form of latent nuclear tracks in polymers. The theory specifically applies for incident ion energies E greater-than-or-equal-to E(max), where E(max) is that energy corresponding to the peak in the electronic stopping power Se for the particular ion/target combination. It is assumed that basic ionization processes which create irreversible damage in the polymer by means of fundamental bond-breaking events along the particle trajectory totally dominate in track formation. Isolated bond-breaking events, extended regions of damage, and implanted impurity atoms all play key but competing roles in a diffusion scenario leading towards aggregation and growth of macroscopic radiation damage. Evolution of the accumulated damage pattern is calculated using an appropriate set of coupled rate equations which describe the various processes involved.