Olivine-type phosphate LiMgPO4 doped with rare-earth elements is currently considered as a new dosimetric material suitable for both OSL and TSL applications and able to compete with top commercial ...detectors. In this work, the samples of LiMgPO4:Er3+ were synthesized by the conventional solid state reaction method. We first studied X-ray luminescence and thermally and optically stimulated luminescence in LiMgPO4:Er3+ in detail. Our studies included the structure refinement, DFT calculations, which predicted the preferred positions of both erbium and charge-compensating vacancies, and UV-vis spectroscopy. We showed that the thermoluminescence spectrum of irradiated LiMgPO4:Er3+ does not contain components caused by the 4f–4f transitions in erbium, but coincides with the spectrum of the phosphate matrix with two broad bands at 360 nm and 650 nm. We discovered a high OSL and TSL output in LiMgPO4:Er3+, despite the nonradiative deexcitation of erbium ions.
Pure and terbium-doped lithium-magnesium phosphate LiMgPO4 was investigated with respect to its thermoluminescent properties. The samples were synthesized by solid state, ultrasonic spray pyrolysis, ...as well as by melting and quenching methods. To predict the terbium site, ab initio calculations were carried out. Additional treatment in atmospheres with different oxygen partial pressures was used. The larger is the concentration of oxygen in the atmosphere and, accordingly, the smaller is the quantity of surface oxygen vacancies, the greater is the intensity of thermoluminescence. For a better understanding of thermoluminescence in LiMgPO4 and LiMgPO4:Tb, the TL spectra were recorded. It was concluded that the thermoluminescence of LiMgPO4:Tb is additively composed of the signals of the matrix and activator ions.
A prototype of a skin dosimeter with a lower limit of the measured dose range of 100 μSv has been created for an automated system of individual dosimetric control that takes the readings with the use ...of the effect of optically stimulated luminescence. The energy and dose characteristics of this prototype meet Russian and foreign nuclear safety standards. The obtained results became possible due to the development and implementation of the new approach to the creation of an irradiation-sensitive layer with a mass thickness of 5 mg/cm
2
on the detector surface. This is described in this paper. The approach is based on a special laser treatment of the detector surface. The logic of the parameter selection for this treatment is regarded with special attention in this paper.
Unusual intrinsic thermoluminescence in LiMgPO 4 :Er Kellerman, D G; Kalinkin, M O; Abashev, R M ...
Physical chemistry chemical physics : PCCP,
2020-Dec-16, 2020-12-16, Letnik:
22, Številka:
47
Journal Article
Recenzirano
Olivine-type phosphate LiMgPO4 doped with rare-earth elements is currently considered as a new dosimetric material suitable for both OSL and TSL applications and able to compete with top commercial ...detectors. In this work, the samples of LiMgPO4:Er3+ were synthesized by the conventional solid state reaction method. We first studied X-ray luminescence and thermally and optically stimulated luminescence in LiMgPO4:Er3+ in detail. Our studies included the structure refinement, DFT calculations, which predicted the preferred positions of both erbium and charge-compensating vacancies, and UV-vis spectroscopy. We showed that the thermoluminescence spectrum of irradiated LiMgPO4:Er3+ does not contain components caused by the 4f-4f transitions in erbium, but coincides with the spectrum of the phosphate matrix with two broad bands at 360 nm and 650 nm. We discovered a high OSL and TSL output in LiMgPO4:Er3+, despite the nonradiative deexcitation of erbium ions.
The main elements of a developed portable radiometric system (PRS) and options for its application are discussed. When developing the PRS detector modules, silicon photomultipliers were used that ...made it possible to considerably reduce the size of these modules. Devices and systems of this kind find application in solving various problems of medical radionuclide diagnostics that require an increased field of view, an extended research time range, and mobility. The main goal of this work was to find the optimal configuration of PRS elements to ensure its minimum size and, at the same time, the maximum radiation detection efficiency, taking into account the features of the objects under study and the kinetics of the processes occurring in them. An algorithm for selecting the minimum amount of activity of a radioactive preparation required for each study is additionally considered.
It is shown that complex aggregate centers of oxygen divacancy type (F2 centers) and interstitial aluminum type near the anion vacancy (Ali) are formed in anion-deficient crystals of corundum ...(α-Al2O3-δ) and beryllium oxide (BeO1-δ) under thermo-optical treatment (TOT). These centers are similar to those created in stoichiometric α-Al2O3 and BeO crystals under neutron irradiation. It is important to note that thermal stability of the TOT-created complex centers is higher than that of similar neutron-induced centers. It is also established that the probability of their formation is related to the temperature of the TOO, the wavelength of the stimulating light, and the initial anionic deficiency manifested as F+ and F centers (anion vacancies with one and two electrons, respectively).
•Thermo-optical treatment (TOT) can create complex centers in wide-gap anion-deficient oxide.•These centers are more thermally stable than neutron- and electron-induced centers.•Their creation at TOT depends on temperature and supplied energy density of UV light.•TOT of α-Al2O3-δ creates complex centers in most effectively at 1000 K and 15 J/cm2.
A method for monitoring the degradation of the optical density in films of polytetrafluoroethylene and its modification, a copolymer of tetrafluoroethylene and ethylene, irradiated by electrons with ...energies of 100 keV and 10 MeV is described. The method is based on measuring the optical density of irradiated films in the photon energy range of 1–6 eV and is confirmed by established “dose–optical absorption” relationships. In particular, using the described method, a completely different nature of the radiation degradation of the optical properties of the two types of films under study was discovered. With an increase in the irradiation dose, “clearing effect” in the region of 2–5 eV and the occurrence of an absorption band at 5.6 eV are observed in polytetrafluoroethylene films. With a similar dose increase, three absorption bands at 4.0, 4.6, and 5.5 eV appear and grow in films of copolymer of tetrafluoroethylene and ethylene. The evidence of the critical role of the optical density of films in the functioning of space technology devices is given.
Abstract The KLOE electromagnetic calorimeter is expected to be reused in the Near Detector complex of the DUNE experiment at Fermilab. The possible substitution of traditional Photomultiplier Tubes ...(PMTs) with Silicon Photomultipliers (SiPMs) in the refurbished calorimeter is the object of this investigation. A block of the KLOE lead-scintillating fiber calorimeter has been equipped with light guides and external trigger scintillators. The signals induced by cosmic rays and environmental radioactivity have been collected by SiPM arrays on one side of the calorimeter, and by conventional PMTs on the opposite side. Efficiency, stability, and timing resolution of SiPMs have been studied and compared with KLOE-PMTs performance. Conclusions about the convenience of substituting PMTs with SiPMs are drawn.
Lithium magnesium phosphate LiMgPO
4
is one of the most promising materials for luminescence dosimetry. In this paper, we consider methods for the synthesis or additional processing of this material, ...such as microwave, hydrothermal, and flux techniques, as well as melting followed by quenching, which makes it possible to enhance its thermoluminescence by increasing the crystallinity of the samples and improving grain contacts. The best properties are shown by the LiMgPO
4
–Na
2
B
4
O
7
composite.
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