Thermoluminescence properties of LiF(Mg,Cu,P) with different copper concentrations

TL emission characteristics have been studied from LiF(Mg,Cu,P) samples prepared at the Institute of Nuclear Physics in Krakow, Poland in which the Cu concentration has been varied from 0.002 mol% to 0.5 mol% while the Mg content (0.2 mol%) and P content (1.25 mol%) were kept constant. Thermoluminescence has been recorded both as function of temperature and wavelength and absorption spectra were derived from diffuse reflectance measurements. The TL response of main dosimetry peak 4 increases with increasing Cu concentration up to 0.02 mol% and decreases for higher Cu content. With increasing Cu concentration the high temperature TL decreases. The emission spectra can be described with two overlapping emission bands peaking at 352 nm and 387 nm. The ratio of the intensities of both emission bands alters with temperature and Cu concentration. The high temperature thermoluminescence shows more 352 nm emission. No unique role of copper as trapping or as luminescent centre could be derived. Copper appears to play an indirect role in the trapping of charge carriers, possibly reducing the occurrence of higher order Mg defects and/or the improvement of the efficiency of the luminescent centre.