The influence of post-exposure heating on the stability of MCP-N (LiF:Mg,Cu,P) TL detectors.
Post-exposure annealing of highly sensitive LiF:Mg,Cu,P (MCP-N) detectors, at 100 degrees C over 10 or 20 min prior to readout, is usually recommended for routine dosimetry. The purpose of this anneal is to eliminate low-temperature peaks, especially peak 3, which fades at room temperature in about 3 months. However, as this annealing procedure does not entirely eliminate peak 3, 10% of its thermoluminescent (TL) signal still being readable, a fading correction must be applied. The aim of this work was to optimise the conditions of post-exposure treatment, i.e. its temperature and duration, in order to facilitate the use of MCP-N detectors in routine dosimetry. MCP-N detectors were annealed in standard conditions, i.e. at 240 degrees C over 10 min and exposed to a dose of 5 mGy (137Cs). For post-exposure annealing, six different temperatures between 100 degrees C and 150 degrees C and two time periods (10 and 20 min) were tested. TL glow curves were deconvoluted with the GCA code. A post-exposure anneal at 120 degrees C over 10 min was found to be optimal. Heating at this temperature eliminates 100% of the TL signal of peak 3, while maintaining the area and maximum intensity of the main peak 4 unchanged. In this case, no fading correction needs to be applied. Annealing at higher temperatures, up to 150 degrees C, results in a loss of peak 4 signal, and is therefore not recommended.
Budzanowski
M
M
Institute of Nuclear Physics, Kraków, Poland. maciej.budzanowski.@ifj.edu.pl
D003300:Copper; D005459:Fluorides; D006358:Hot Temperature; D018020:Lithium Compounds; D008274:Magnesium; D010758:Phosphorus; D012016:Reference Values; D012680:Sensitivity and Specificity; D013819:Thermoluminescent Dosimetry / Q000379:methods*
D018020:Lithium Compounds; C027651:lithium fluoride; D010758:Phosphorus; D003300:Copper; D008274:Magnesium; D005459:Fluorides