Correlation of optically and thermally stimulated luminescence of natural fluorite pellets

• CaF2:NaCl pellets are extremelly useful as dosimetric materials.
• Only part of the defects responsible for the TL signal from fluorite is optically active.
• NaCl signals affects the TL and OSL signals from the pellets.
• NaCl OSL signal can be avoided with a pre-heat or after about 1 h waiting time.

Natural fluorite (CaF2), a dosimetric material of large usage, presents Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL). This study examined the behavior of TL and OSL (stimulated with Blue LEDs) signals from the Brazilian natural fluorite pellets with NaCl as binding agent, as well as their correlations, in order to study and optimize the dosimetric process with this material. A series of experiments were conducted, basically with thermal treatments before OSL acquisition, and optical bleaching before TL readout. The role of NaCl in the TL and OSL emission was investigated. It was observed that natural CaF2 TL signal is still ample to be used in dosimetric applications, as dose re-assessment in personal dosimetry after an OSL measurement. Also it was verified that the fluorite OSL signal is extinguished by a 350 °C heating and that NaCl has no contribution to the stable part of the OSL signal.