| 题名 | 高温闪烁晶体Ce:YAP的生长与性能测试 |
| 作者 | 李涛 |
| 学位类别 | 硕士 |
| 答辩日期 | 2002 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 徐军 |
| 关键词 | Ce:YAP闪烁晶体 晶体生长 晶体缺陷 浓度分布 性能测试 |
| 其他题名 | Study on the growth and properties of high-temperature scintillator crystal Ce:YAP |
| 中文摘要 | 该论文主要从以下几个方面展开工作:1.探索利用提拉法生长Ce:YAP晶体合适的温场条件、工艺参数及工艺流程,成功解决了晶体生长过程中容易出现的开裂及孪晶问题,并利用了提拉法生长了不同掺杂浓度的直径为30~35mm,等径部分长度为70~80mm的外形完整的Ce:YAP晶体.2.用同步辐射X-射线形貌照相研究了Ce:YAP晶体中的缺陷,其缺陷类型主要是生长条纹和包裹物.详细描述了YAP晶体的变色现象并研究了不同退火气氛及掺杂离子对其颜色变化的影响,提出用电子陷阱O<'->模型能合理解释其变色现象.3.利用电感耦合等离子体发射光谱法及电子探针分析了掺杂剂Ce离子在晶体中的分布.结果表明:Ce离子在晶体中的轴向分布基本呈线性变化;直径方向上,在晶体中心的"核心"区浓度较高,偏离"核心"区其分布比较均匀.4.测定了Ce:YAP晶体在200~500nm范围内的吸收谱,晶体的发射谱及激发谱;测试了标志闪烁晶体性能的最重要的两个参数光产额及衰减时间常数;并分析了不同掺杂浓度、退火气氛、晶体取向及厚度对它们的影响. |
| 英文摘要 | A scintillation material is a kind of converter transforming the energy of high energy photons(X-ray, γ-ray) or particles (proton, electron, α-particle, etc) into UV/visible photons, which are easily detected. It has wide applications for radiation detection in different fields such as high energy physics, nuclear physics, nuclear medical diagnostics and industrial measuring systems. In recent years, the development of scientific research has required scintillation materials with improved properties and much effort has been focused on materials with fast response time and high light yield. Ce:YAP, as a kind of high-temperature scintillator crystal, is mainly characterized by a high light output of 40% relative to NaI:Tl; a short decay time constant of 25～30ns; emission spectrum being well coupled with the sensitivity of typical photomultipliers; a moderate efficiency for γ-ray detection and good chemical stability. As a result , Ce:YAP presents enormous potential application in γ-ray detection and nuclear medical diagnostics, and the research on Ce:YAP bears much significance. Several following investigations were carried out in this paper: 1. Cracking and twinning of Ce:YAP crystals which were prone to occur in the Czochralski growth of YAP crystals were successfully overcome by investigation on the appropriate temperature gradient, growth parameters and growth process. Perfect Ce:YAP crystals with different Ce doping concentrations were grown by Czochralski method with diameter of 30～35mm and length of 70～80mm with uniform diameters. The imperfection in the Ce:YAP crystals was revealed by synchrotron radiation X-ray topography method, especially growth stripes and inclusions. The color changes of YAP crystal were described in detail and different conditions, such as annealing atmosphere and doping ions, which could greatly influence the color change were studied. This color change could be interpreted reasonably using the O- centers model. The concentration distribution of Ce ions in the crystals was analyzed by means of ICP-AES and electronic microprobe. The results showed that Ce concentration changed linearly in the axis direction and that in the radial direction, the concentration was higher in the "core" area and it was uniform apart from the "core". The absorption spectra of Ce:YAP at 200～500nm, the fluorescence spectra and excitation spectra were measured; two parameters, light yield and decay constant, which were most important to scintillation crystals, were measured; the effects of different conditions like different doping concentrations, annealing atmosphere, different crystal directions and thickness, to the crystal performance were investigated. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16609]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 李涛. 高温闪烁晶体Ce:YAP的生长与性能测试[D]. 中国科学院上海光学精密机械研究所. 2002. |
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