High-dose characterization of different LiF phosphors

The dose response of three LiF TLDs: standard LiF:Mg,Ti (denoted MTS), high-sensitive LiF:Mg,Cu,P (MCP) and a recently developed in Kraków version of LiF:Mg,Ti with modified activator composition (MTT) and increased high-LET response was measured. The TLDs have been exposed to 60Co gamma-rays, up to dose of 10 000 Gy, i.e. beyond saturation dose of the main dosimetric peaks, which corresponds to ca. 1000 Gy. The measured glow-curves were deconvolved into separate peaks with first order kinetic function (using self-developed GlowFit software). The dose response of the main peaks was found to be supralinear for MTS and sublinear for MCP detectors, as expected. The dose response of MTT was found to be even more supralinear than that of MTS. An interesting effect has been observed with regard to glow-curve shape of MCP detectors. Up to a dose of 1 kGy it remains practically unchanged, while for higher doses a strong growth of high-temperature peaks is observed. In the same dose region a decrease of the main peak of MCP with increasing dose is observed, unlike LiF:Mg,Ti detectors.