Comparison of TL Spectra of Co-Doped Dosimetric Materials

Wavelength resolved spectra of the dosimetric materials CaSO4 and MgB4O7 with the rare earth (RE) ions Dy and Tm are presented. The study of co-doped samples provides, within a single sample, unequivocal evidence of a glow peak displacement of the two dopants. In the case of the main dosimetric peak for CaSO4 at γ220 deg. C, a reproducible systematic temperature difference of 7 to 8 deg. C is observed between the glow peaks near 230 to 240 deg. C for Tm and Dy. No comparable displacement is detected between Tm and Dy for the main dosimetric peak for MgB4O7 at about 180 deg. C. However, higher temperature glow peaks above 300 deg. C display a noticeable displacement of Dy and Tm on the scale of 30 deg. C. This research provides further evidence supporting the view that the RE ions could form part of a complex defect acting as both charge trap and recombination centre. (author)