Optical absorption and thermoluminescence in LiF: Mg, Ti (TLD-100). Dependence on linear energy transfer

Abstract

Thermoluminescence (TL) and optical absorption (OA) studies in LiF TLD-100 single crystals are carried out after thermal neutron and y-irradiations. For thermal neutrons, similar to the T L peak VII (300 "C) to peak V (225 "C) height ratio, the 250 nm to 310 nm OA band height ratio is quite large as compared to that for y-rays. The changes in 250 nm band during peak VII readout reveal that the preferential increase in 250 nm OA band for thermal neutrons is associated with an increase in peak VII T L only, thereby indicating that the peculiar LET (linear energy transfer) dependence of peak VII can be a direct consequence of the two-hit nature of its traps. This conclusion receives further support from the similar LET dependence exhibited by M (448 nm)-centres and peak VII centres in TLD-100. The structure, i.e. the two-hit nature, and the position of OA of M-centres in LiF are already well established. I )

Photoluminescence ofF-aggregate centres in thermal neutron irradiated LiF TLD-100 single crystals

“…When electrons are available, the F~-and F~-centres capture electrons and transform to F2 and F3 centres respectively. Unlike the case with ?-rays, the OA band around 445 nm in LiF TLD-100 can be observed even at relatively low thermal' neutron fluences (Lakshmanan 1994). This has prompted us to conduct a fluorimetric study of the F-aggregate centres in thermal neutron and ?-ray irradiated LiF TLD-100 and undoped LiF crystals.…”