High-dose high-temperature emission of LiF:Mg,Cu,P: Thermally and radiation induced loss & recovery of its sensitivity

Highly sensitive LiF:Mg,Cu,P (MCP) detectors enable measurements of radiation doses from tens of nanograys up to a few kilograys, where the saturation of the signal of the main dosimetric peak occurs. Thanks to the recently observed high-dose high-temperature emission of MCP detectors heated to temperatures up to 600 °C after exposures to radiation doses ranging from 1 kGy to 1 MGy, a new method of thermoluminescent measurement of radiation doses has been recently developed at the Institute of Nuclear Physics (IFJ). This method can measure doses ranging from micrograys up to a megagray. So far, high dose measurements were performed on fresh MCP samples and each detector was used only once, because as a result of these measurements, the detectors lose their sensitivity to a large extent. In this study, a specific thermal treatment intended to fully restore the loss of MCPs TL sensitivity was sought. We have investigated several annealing procedures, applying different temperatures (from 400 °C up to 700 °C) for different periods of time (10–30 min) in argon atmosphere. In this way we were able to recover MCP sensitivity fully, allowing for reuse of the samples after high-dose irradiation and high-temperature measurement.

► High-dose high-temperature TL emission is present in LiF:Mg,Cu,P’ glow-curves.
► LiF:Mg,Cu,P can measure doses ranging from below 1 μGy to about 1 MGy.
► Thermally-induced sensitivity loss of the samples can be recovered.
► Sensitivity damage of the samples after high-dose measurements is fully reversible.
► High-dose measurements changes to the structure of the material are reversible.