Fluorescent imaging of heavy charged particle tracks with LiF single crystals

Radiophotoluminescence of F-2 and F-3(+) color centers in LiF was exploited for imaging tracks of energetic heavy charged particles. LiF crystals were irradiated with helium, carbon, neon, silicon and iron ions at the HIMAC accelerator in Chiba, Japan. The patterns created by radiation were visualized with a wide-field fluorescent microscope under blue-light excitation. The shape of the visible tracks was found not to depend on ion type and energy. The full width at half maximum of track profiles was in all cases around 500 nm, what corresponds with the resolution limit of the microscope, which was estimated to be 420 nm. On the other hand the fluorescent intensity of tracks was found to increase in a linear manner with the increasing LET. This indicates possibility of obtaining some spectrometric information on the radiation field.