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Abstract

Dynamic Monte Carlo simulations of primary defect aggregation

in tracks of swift heavy ions in alkali halides have been
performed. The study was motivated by recent experimental
findings on dense F-center clusters observed even at 15 K in
LiF irradiated by GeV heavy ions. We relied on a recently
suggested model, which assumes local heating and diffusion of
single defects in their excited electronic state. The main
parameters (migration energy, initial defect concentration,
diffusion time) are estimated from available experimental data.
Simulation results confirm the formation of a core with large
F-aggregates and a broad halo of single and dimer defects
around it. The fraction of large (more than 10 defects)
aggregates in the core is negligible, making ESR detection
impossible. The low sensitivity of the model to changes in
parameters can be explained by its universal features, which we
first report in this paper. Unexpected power laws in the
kinetics of single defect concentrations are also emphasized.
(C) 2002 Elsevier Science B.V. All rights reserved.