Kr and Xe ion induced aggregation processes in LiF crystals during irradiation and thermal annealing

The efficiency of F and F_n center creation in LiF crystals irradiated with 147 MeV Kr and 195 MeV ions was studied via ion fluence and flux. In the case of Kr ions with flux of 8.9×10⁹ ions/(cm²×s) saturation of F centers (∼ 10¹⁹cm⁻³) was observed at a fluence of 10¹² ions/cm². Further irradiation decrease the F center concentration. In LiF irradiated with both ions an enhancement of electron color centers (F and F_n) via flux was observed. In LiF crystals irradiated with Kr ions an enhancement of F_n centers was observed after thermal annealing up to 600 K. The mechanisms of the processes are discussed.