| 1. |
- Devitsin, EG, et al.
(författare)
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Non-stoichiometry defects and radiation hardness of lead tungstate crystals PbWO4
- 2002
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 486:1-2, s. 336-344
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Tidskriftsartikel (refereegranskat)abstract
- It has been stated many times that the formation of radiation infringements in PbWO4 is to a big extent stipulated by the non-stoichiometry defects of the crystals, arising in the process of their growth and annealing. To refine the idea of characteristics of the non-stoichiometry defects and their effect on the radiation hardness of PbWO4, the current study is aimed at the melt composition infringements during its evaporation and at optical transmission of crystals obtained in these conditions after their irradiation ((CS)-C-137 source). In the optical transmission measurements along with traditional techniques a method "in situ" was used, which provided the measurements in fixed points of the spectrum (380, 470 and 535nm) directly in the process of the irradiation. X-ray phase and fluorescence analysis of condensation products of vapours over PbWO4 melt has found PbWO4 phase in their content as well as compounds rich in lead PbO, Pb2WO5 with overall ratio Pb/W (3.2). Correspondingly, the lack of lead and variations in the content of oxygen are pointed out as the major growth defects of nonstoichiometry of PbWO4 crystals. The oxygen variations are determined by the partial oxygen pressure in the atmosphere of growth or annealing of the crystals. The obtained results were compared with known conceptions of PbWO4 crystal colour centres. The possibilities of the formation of these centres accounting for the discovered loss of lead and oxygen exchange between the external medium and the crystal were considered. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 2. |
- Nagirnyi, V, et al.
(författare)
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Energy transfer in ZnWO4 and CdWO4 scintillators
- 2002
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 486:1-2, s. 395-398
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Tidskriftsartikel (refereegranskat)abstract
- A systematic spectroscopic study of oriented single ZnWO4 crystals was performed using UV and synchrotron excitation. Emission and phosphorescence spectra in the energy region 1-4 eV as well as reflection spectra and excitation spectra of various emissions and phosphorescence in the energy region 3.5-32eV were studied at 4.2-300K using synchrotron radiation. The results are compared to those available for CdWO4. The peculiarities of the band structure and those of excitonic and electron-hole processes in the systems investigated are discussed.
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| 3. |
- Nagirnyi, V, et al.
(författare)
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Iron-related luminescence centers in ZnWO4 : Fe
- 2002
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Ingår i: Radiation Effects and Defects in Solids. - : Informa UK Limited. - 1042-0150 .- 1029-4953. ; 157, s. 1123-1123
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Tidskriftsartikel (refereegranskat)abstract
- A systematic spectroscopic study of single ZnWO4 :Fe crystals with different iron concentrations has been performed under excitation by ultraviolet light, by synchrotron radiation or under photostimulation by near-infrared light. The luminescence of Fe3+-related centres has been studied. It is shown that iron centres of different types efficiently promote the formation of crystal defects at low temperatures. Electrons and holes can be trapped near Fe2+ or Fe3+ ions, which is further revealed in phosphorescence, thermostimulated or photostimulated luminescence. At room temperature the main effect of iron impurity is to reduce the light yield of a ZnWO4 scintillator.
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