The composite structure of peak 5 in the glow curve of LiF:Mg,Ti (TLD-100): Confirmation of peak 5a arising from a locally trapped electron-hole configuration

The hypothesis that glow peak 5a arises from localised e-h capture is confirmed by the following experimental observations: (i) The high conversion efficiency (CE) (CE_5a→4 = 3 ± 0.5) of peak 5a to peak 4 (a hole-only trap) deduced from detailed I_m-T_stop optical bleaching studies at 3 10 nm compared to the much lower CE of peak 5 (an electron-only trap) (CE_5π[4 = 0.0026 ± 0.012). (ii) The lack of an increase in the sensitivity of glow peak 5a following 2.6 MeV and 6.8 MeV He ion irradiation in 'sensitised' material compared to the factor two increase in the sensitivity of peak 5; (S/S₀)_5a = 0.86 ± 0.12, compared to (S/S₀)₅ = 2.0 ± 0.2. (iii) The late entry into saturation of the 2.6 MeV and 6.8 MeV He ion TL-fluence response curves for peak 5a compared to peak 5 in sensitised and normal material resulting in the following values for the track radial saturation parameter; (r₅₀)_5a = 100 ± 20 Ångstroms compared to (r₅₀)₅ = 380 ± 30 Ångstroms. (iv) The low value of 0.1 for the 'track-escape' parameter of peak 5a deduced from the Extended Track Interaction Model analysis of He ion TL fluence response compared to order of magnitude greater values for peaks 5 and 5b.