Influence of thermal treatments on glow curve and thermoluminescence emission spectra of LiF:Mg,Cu,P

Abstract

LiF:Mg,Cu,P is a highly sensitive thermoluminescence material, but loses its sensitivity if annealed at temperatures above 513 K. In this paper, the effects of these annealing temperatures on GR-200A samples are investigated and quantified. The changes in the glow curve and the emission spectrum are investigated as a function of annealing temperature and cooling rate. The return of up to 79% of its sensitivity (after a 633 K for 10 min treatment) is found with a special thermal treatment including a cooling at 40 K min −1 down to 513 K and a dwell time at that temperature for 10 min. Treatments above 513 K lead to both irreversible and reversible processes in the material. A return of TL in the main glow peak is coupled with a decrease of the TL in the high temperature region, which is the main source of the residual signal. Analysis of the emission spectrum shows two emission bands at 347 and 377 nm, of which the latter is influenced by the annealing procedure and can be correlated with the main glow peak, and the other with the residual signal. A comparison with X-ray induced emission spectra indicates that the luminescence processes in LiF:Mg,Cu,P materials may be explained by centre-to-centre recombination.