Dosimetric characterisation of the high temperature peaks of LiF:Mg,Ti and CaF2:Tm using computerised glow curve deconvolution

Computerised glow curve deconvolution (CGCD) has been used to study the high temperature peaks in both LiF:Mg,Ti (TLD-700, Harshaw) and CaF2:Tm (TLD-300, Harshaw). The dose response of peak 7 in TLD-700 is supralinear and is strongly dependent on photon energy. This behaviour significantly complicates the use of peak 7 to peak 5 ratios in n-γ dosimetry. Peak 6, although linear in its dose response, is difficult to separate accurately from its more intense neighbours and cannot, therefore, be measured reliably below 10 mGy. CaF2:Tm, due to its linear response, is thus definitely superior to LiF:Mg, Ti for n-γ dosimetry, via peak 5 to peak 3 ratios. For environmental dosimetry, peak 3 in CaF2:Tm is a poor choice due to its fading and the presence of a strong, non-radiation induced TL signal of between 5 and 25 μGy which lies directly under peak 3. However, peaks (5 + 6) can be used to measure dose levels down to 9 μGy with the CGCD analysis with no measurable fading. The X ray relative TL response of the peaks in CaF2:Tm appears to be strongly heating rate and/or batch dependent so that the use of peak (5 + 6)/peak 3 ratios for accurate determination of gamma radiation field quality requires further study. (author)