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We investigated the influence of terbium and thulium trivalent rare-earth (RE) ions co-doping on the luminescent properties enhancement of LiMgPO4 (LMP) crystal host. The studied crystals were grown from the melt by micro-pulling-down (MPD) technique. Luminescent properties of the obtained crystals were investigated by thermoluminescence (TL) method. The most favorable properties and the highest luminescence enhancement were measured for Tb and Tm double doped crystals. A similar luminescence level can be also obtained for Tm, B co-doped samples. In this case, however, the low-temperature TL components have a significant contribution. The measured luminescent spectra showed a typical emission of Tb3+ and Tm3+ ions of an opposite trapping nature, namely the holes and electron-trapping sites, respectively. The most prominent transitions of 5D4 → 7F3 (550 nm for Tb3+) and 1D2 → 3F4 (450 nm for Tm3+) were observed. It was also found that Tb3+ and Tm3+ emissions show temperature dependence in the case of double doped LMP crystal sample, which was not visible in the case of the samples doped with a single RE dopant. At a low temperature range (up to around 290 °C) Tm3+ emission was dominant. At higher temperatures, the electrons occupying Tm3+ sites started to be released giving rise to emissions from Tb-related recombination centers, and emissions from Tm3+ centers simultaneously decreased. At the highest temperatures, emission took place from Tb3+ recombination centers, but only from deeper 5D4 level-related traps which had not been emptied at a lower temperature range.

This work is dedicated to the development of new types of composite thermoluminescent (TL) detectors for simultaneous registration of the different components of ionization radiation based on the single crystalline films (SCFs) of Ce3+-doped Lu3−xGdxAl5O12:Ce (x = 0–1.5) garnet and Y3Al5O12:Ce (YAG:Ce) substrates using the liquid phase epitaxy (LPE) growth method. For this purpose, the TL properties of the mentioned epitaxial structures were examined in Risø TL/OSL-DA-20 reader under excitation by α- and β-particles from 242Am and 90Sr-90Y sources. We have shown that the cation engineering of SCF content can result in more significant separation of the TL glow curves of SCFs and substrates under α- and β-particle excitations in comparison with the prototype of such composite detectors based on the Lu3Al5O12:Ce (LuAG:Ce)/YAG:Ce epitaxial structure. Specifically, the difference between the TL glow curves of Lu1.5Gd1.5Al5O12:Ce SCFs and YAG:Ce substrates increases up to 120 K in comparison with a respective value of 80 degrees in the prototype based on the LuAG:Ce/YAG:Ce epitaxial structure. Therefore, the LPE-grown epitaxial structures containing Lu1.5Gd1.5Al5O12:Ce SCFs and Ce3+-doped YAG:Ce substrate can be successfully applied for simultaneous registration of α- and β-particles in mixed fluxes of ionization radiation.

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Several samples of lithium aluminate (LiAlO 2 ) were prepared in an attempt to achieve material, which can be applicable in optically stimulated luminescence (OSL) dosimetry. Both undoped and carbon or copper doped lithium aluminate samples were investigated. The results of preliminary study of theirs reproducibility, sensitivity, dose response characteristic and fading are presented. Applications in mixed field (beta, alpha, neutrons) dosimetry are discussed.

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HIGHLIGHTSThe RPL readouts of LiF detectors were performed for ultra-high doses.Linearity range of LiF RPL signal was investigated.Thermal stability of RPL signal and its connection to CCs are showed.Application of combined RPL/TL is proposed to improve high-dose dosimetry readouts. ABSTRACTThe radio-photoluminescent (RPL) characteristics of LiF:Mg,Ti (MTS) and LiF:Mg,Cu,P (MCP) thermoluminescent detectors, routinely used in radiation protection dosimetry, were investigated after irradiation with ultra-high electron doses ranging up to 1 MGy. The photoluminescence of both types of LiF detectors was stimulated by a blue light (460 nm) and measured within a spectral window around 530 nm. The RPL dose response was found to be linear up to 50 kGy and sublinear in the range of 50 kGy to 1 MGy for MCP detectors and linear up to 3 kGy and next sublinear in the range from 5 kGy to 1 MGy for MTS detectors.For both type of LiF detectors RPL signal is saturated for doses higher than 100 kGy. The observed differences between MCP and MTS may suggest, that the RPL effect in LiF is not entirely governed by intrinsic defects (F 2 and F 3 + centers), but impurities may also have a significant influence. Due to the non-destructive character of the RPL measurement, it is suggested to apply combined RPL/TL readouts, what should improve accuracy of high-dose dosimetry.