Study On Preparation And Nuclear Physics Performance Of Thermal Neutron Detection Glass Scintillator

With the use of thermal neutron detecting in nuclear energy, the discovery ofradioactive isotope and nuclear physics research,the research of thermal neutrondetection materials has attracted more and more attention of world material andphysical scholars. Because of its unique superiority in such aspects as materialcomposition design, chemical stability,thermal shock resistance and large sizepreparation, glass scintillator has become the focus of research in the field of neutrondetection.Neutrons cannot be directly detected by material ionization because of neutralparticles. Therefore conventional glass scintillator cannot achieve the purpose ofdetecting neutrons. Internationally it is usually to change the energy of neutrons tothe UV or visible light with the use of energy conversion materials which can bedetected by a variety of methods. The aim of this thesis is to develop a new kind ofvaluable glass scintillator, and to clearly know the mechanism of its scintillating andthermal neutron detection through the study on its composition, preparation,scintillating and nuclear physics performance, and to further enrich and develop thetheory and application of glass scintillator. This research has important theoreticaland practical significance.The indications of the study are as follows.:By using lithium-6for target nuclide, Ce³⁺for activator ions, Li-Al-Si asglass matrix, high-performance thermal detection glass scintillator can besuccessfully produced, which has such characteristics as short attenuation time, goodtemperature performance, excellent performance of n-γdiscrimination, togetherwith the glass material chemistry stability, good performance on thermal shock,and easy production of large size.In glass matrix systems, there are different degrees of concentration quencheseffects between lithium-6and Ce³⁺, in which the importing of La³⁺has significantsuppression effect to the concentration quenches effect of Ce³⁺ï¼›Light basicity ofglass components has important effect on scintillating performance of glass scintillator,the higher of light basicity, the longer of emission wavelength, the biggerof the Stokes displacementï¼›Since there are Gd³⁺-Ce³⁺energy transfer mechanism,the introduction of Gd³⁺is helpful for improving the luminous intensity of glassscintillator.Melting process has decisive effect on the performance of thermal detectionglass scintillator. It can guarantee Ce³⁺single valence stability during the glassmelting process with the method of using strong reducing atmosphere and theappropriate introduction of Ce³⁺and valence ions. By using glass second meltingprocess and special glass melting devices, some technical problems as glassscintillation tiny bubbles, stripes and uniformity can be effectively solved,at thesame time Ce³⁺single valence stability can be guaranteed.Comparing with other oxide glass system, excitation and emission peak of Ce³⁺doped aluminum glass matrix produce obvious red-shift phenomenon, and stokesdisplacement is bigger. Aluminum glass has many other advantages as higher densityand larger refractive index, and is expected to become excellent optical fiber matrixmaterial.The results of the study have enriched and developed research theory of thermalneutron detection glass scintillator. It has innovation in glass composition designingand preparation, especially in the bubbleless and stripeless melting process understrong reduction melting atmosphere. This technology breaks the problem thatplatinum crucible cannot melt optical glass under the strong reduction atmosphere inthe traditional process, and also solves the long-term technical problem that glassscintillator cannot be applied to reality. Therefore, it has strong application value.Now,neutron dosimeters assembled with the glass scintillator have been used inmany fields such as nuclear power plant, neutron radiation monitoring station, postprocessing field, and will be used in the future for neutron flight test, neutronradiography, NDT, and oil well logging fields.