Fabrication And Properties Of Glass Composites For Radiation Detection

Scintillator as a radiation detection material has an especially important role in nuclear medicine,high-energy physics,homeland security and atomic energy,and is an important tool for effective detection of various ionizing radiation(e.g.,X-rays,?-rays)and high-energy particles(e.g.,?-particles,?-particles,neutrons).Scintillators have been developed for more than 100 years and many inorganic and organic scintillator materials with excellent properties have been discovered.Among them,inorganic single crystal materials are one of the most widely used scintillators,such as Bi₄Ge₃O₁₂,Lu_1.8Y_0.2Si O₅:Ce,Gd₃Al₂Ga₃O₁₂:Ce and Na I:Tl.The glass material,on the other hand,has outstanding advantages in terms of preparation and processing.With the increasing requirements for scintillator performance and the diversification of application scenarios,there are still many difficulties and pain points for single materials.And composite materials can provide unlimited possibilities for the development of scintillator materials through integrating a variety of materials.In order to further expand the types of scintillator materials,we seek better comprehensive improvement in sample preparation,luminescent performance,detection ability and so on through the coordination of the characteristics of different substances:(1)the chloride crystal-glass composite scintillator materials were investigated systematically.The composites were prepared by an efficient method of glass melt quenching,using chloride crystal powder and glass oxide powder.By using the viscous flow state of the glass phase to provide a buffer for the volume change during rapid solidification,the defect-free and transparent Sr Cl₂-B₂O₃,KCl-P₂O₅ and Rb Cl-P₂O₅ composites were obtained.The relationship between the two-phase density,refractive index and the transparency of the composites were determined by systematic experimental analysis of the phase-separated structure and chemical composition of the transparent composites.And the transparent composite scintillator materials with the phase separation structure of glass-phase-encapsulated crystal phase were obtained by suitable raw material composition and melting process.These methods have the following two outstanding advantages:on the one hand,the phase separation structure can be controlled by adjusting the ingredients of the composite materials,and the crystal content can be continuously adjusted at 0?86 vol%;on the other hand,the deliquescence of chloride crystals can also be alleviated by coating the crystal phase with the glass phase.In addition,the phase separation structure can be extended to the different combinations of alkali chlorides,alkaline earth chlorides with oxides,which provides a new idea for preparing transparent composite scintillation materials with high chloride crystal content in an efficiency and low-cost way.(2)Eu-doped Sr Cl₂-B₂O₃ transparent composite scintillator materials were designed and prepared based on the above method and applied to the detection of thermal neutrons.Using the above experimental results,Eu-doped Sr Cl₂-B₂O₃ transparent composite scintillator materials were efficiently prepared by melt quenching method,and Eu ions existed as Eu²⁺ions in the chloride crystal phase,which exhibited bright blue luminescence under UV excitation.Meanwhile,the luminescence patterns of Eu-doped Sr Cl₂-B₂O₃ transparent composite scintillator materials with different chloride crystal contents were experimentally investigated,and it was found that the luminescence of Eu²⁺ions was significantly stronger than that of Eu³⁺ions under the excitation of UV light,X-rays and?particles.Monte Carlo simulation was used to investigate the effect of the ratio between the boundary glass phase and chloride crystal phase in the Sr Cl₂-B₂O₃ transparent composite scintillator materials on the detection effect of thermal neutron has also been investigated.The influence of crystal phase content,material thickness and ¹⁰B abundance on the thermal neutron detection effect were determined,and optimized design was provided for the preparation of transparent composite samples for neutron detection.In practical experiments,the transparent composite samples with both natural and 95%abundance of ¹⁰B isotope can achieve effective thermal neutron detection.(3)Ce-doped Lu-Y-Si,Li-Mg-Al-Si and B-Al-Si glass scintillating fibers were prepared.The composite glass scintillating fiber was fabricated by melt-in-tube method by using Ce doped Lu_1.8Y_0.2Si O₅ crystal,Li-Mg-Al-Si and B-Al-Si glass as the core materials.The experimental results show that the composite glass scintillating fiber has a perfect core-cladding structure,and the element diffusion is controllable.The core of the composite glass scintillating fiber exhibits bright blue emission of Ce³⁺ion under the excitation of ultraviolet light and X-ray.The core of Lu-Y-Si composite glass scintillating fiber contains Lu element with high atomic number,which can be used for X-ray detection.The core of Li-Mg-Al-Si and B-Al-Si composite glass scintillating fiber contains ⁶Li and ¹⁰B isotopes,which make the scintillating fiber useful for thermal neutron detection.In addition,because of the similarity between the constituents of the composite glass scintillating fiber and that of the commercial silica fiber,the prototype device of the glass scintillating fiber detector for X-ray detection is fabricated through the fusion splice,thus realizing the real-time remote X-ray monitoring.(4)The interaction effect between Ce-doped Lu-Y-Si,Li-Mg-Al-Si and B-Al-Si composite glass scintillation fibers and radiation is explored by Monte Carlo simulation.It was found that due to the small size and core-cladding structure of the scintillating fiber,the range of the secondary particles generated by the interaction of high-energy radiation with the scintillating fiber has an important effect on the amount of energy deposited in the core area.Lu-Y-Si composite glass scintillating fiber has good absorption and linear response capabilities for low-energy X-rays.However,with the increase of X-ray energy,Compton scattering and the escape of secondary electrons from the fiber core have a negative impact on the radiation detection property and linear response capabilities of the scintillating fiber.As for the Li-Mg-Al-Si and B-Al-Si composite glass scintillating fibers,the secondary particles produced by the nuclear reaction with thermal neutron have a shorter range,so that more energy can be deposited in the core area.At the same time,it was also found that the ¹⁰B isotope with lower energy produced by the nuclear reaction has a shorter range of the secondary particles,and its energy deposition value in the core area is slightly higher than that of the ⁶Li isotope with higher energy produced by the nuclear reaction.This further illustrates the important influence of the range of the secondary particles on the radiation detection performance of the composite glass scintillating fiber,and also provides suggestions for the design and application of the composite glass scintillating fiber in future work.