钨酸铅（PbWO4）闪烁晶体研究进展

钨酸铅（ＰｂＷＯ４）闪烁晶体是拟使用于西欧大型强子对撞机（ＬＨＣ）中精密电磁量能器量有希望的候选者，本文概要介绍了近年来国际上对于钨酸铅晶体的研究进展。包括它的闪烁性能、发光机制、辐照硬度和杂质效应等。本文最后列出了欧洲核子研究中心（ＣＥＲＮ）的ＣＣＣ组最近对７５根大尺寸ＰＷＯ晶体综合测试的统计结果。这有助于建立批量生产ＰＷＯ晶体的质量监控方法。     

无机闪烁材料研究进展

闪烁材料的发展已有一百多年的历史,其中无机闪烁材料应用最广、数量最多。无机闪烁材料主要包括陶瓷闪烁材料、晶体闪烁材料和玻璃闪烁材料三大类型。闪烁材料的闪烁性能主要包括光输出、透明性、衰减速率、高能粒子阻止能力和抗辐照损伤能力等。无机闪烁材料在影像核医学诊断、高能离子探测、工业在线无损检测以及油井勘测等领域有着广泛的应用。介绍了无机闪烁材料的三大发展阶段与三大类型,对部分重要无机闪烁材料的闪烁性能做了对比,并概括了闪烁材料的应用,展望了其发展前景。     

钨酸铅晶体的生长及其闪烁性的研究

采用提拉法生长出直径２０－２５ｍｍ,长２５－３０ｍｍ优质ＰｂＷＯ４及Ｌａ＾３＋、Ｍｇ＾２＋、Ｍｏ＾６＋和Ｂｉ＾３＋掺杂ＰｂＷＯ４晶体。测试了晶体的Ｘ射线衍谢谱、透射光谱、激发发射光谱、光产额、抗辐照性能和发光衰减时间。总结并解释了掺杂对ＰｂＷＯ４晶体性能的影响以及氧退火对晶体抗辐照性能的影响,探讨了掺杂改善晶体闪烁性能的可能性。     

无机闪烁晶体及其应用

本世纪４０年代后期发现ＮａＩ：Ｔｌ晶体具有优良的闪烁特性后，ＮａＩ：Ｔｌ被广泛应用于Ｘ射线和γ射线的探测技术。随着核探测技术在医学、物理、化学、地质勘探等科学技术领域中的发展，一系列无机闪烁晶体，如ＢＧＯ、ＣＷＯ、ＣｓＩ：Ｔｌ、ＣｓＩ等相继问世，并在这些领域中得到了应用。近年来，为了提高核医疗设备如ＰＥＴ等的性能和建造大型高能物理实验装置，如ＳＳＣ和ＬＨＣ，对新型快速、高密度、耐辐照的无机闪烁晶体     

闪烁晶体PbWO4的研究现状

综述新型闪烁晶体ＰｂＷＯ４的研究现状，着重评价其中的不同发光表现，透射光说和抗辐照损伤的个体差异，晶体结构和组分挥等，同时剖析了颇具代表性的几种绿光机的机制。     

X射线激发Ce^3＋掺杂硼酸盐玻璃的闪烁发光

实验研究了Ｃｅ＾３＋掺杂６４Ｂ２Ｏ３－３６ＢａＯ,７５Ｂ２Ｏ３－２５Ｌａ２Ｏ３玻璃的闪烁发光。在８０ｋＶ加速电压、阳极电流为５ｍＡ的高能Ｘ射线激发下闪烁光强为同要条件下闪烁晶体Ｎａｌ（Ｔｌ）的３％～４％。对影响闪烁光输出的因素进行了分析。结果表明,Ｃｅ＾３＋的自吸收和Ｃｅ＾４＋离子的荷移吸收是降低闪烁光输出的主要因素;含镧硼硅酸盐玻璃系统可作为发展高密度玻璃有希望的系统;闪烁玻璃的制备技术对提高闪     

Ta：PbWO4晶体闪烁性能的研究

报道了在ＰｂＷＯ４晶体中掺进Ｔａ２Ｏ５生长Ｔａ：ＰｂＷＯ４晶体的研究结果。测定了核晶体的透过率、发光效率和抗辐照损伤能力，研究和探讨了Ｔａ：ＰｂＷＯ４晶体闪烁性能增强的机理。     

超薄Ce:YAG闪烁晶体用于高分辨X光成像

正近期,中国科学院上海光学精密机械研究所中科院强激光材料重点实验室利用提拉法生长出的高品质Ce∶YAG闪烁晶体开展了高分辨率X射线成像系统核心器件——闪烁体研制工作,成功制备了尺寸为30 mm,厚度为30~45μm的高品质闪烁晶体元件,并和中科院上海应用物理研究所合作,研制基于超薄Ce∶YAG闪烁晶体的高分辨X光探测器,实现X光辐照条件下高分辨成像。在同等实验条件下,与Crytur公司同类晶体对比,上海光机所研制的     

新型闪烁晶体NaBi(WO4)2的研制及闪烁性能的研究

报道了新型闪烁晶体ＮａＢｉ（ＷＯ４）２的生长。测试了晶体的透过率，抗辐照损伤能力和发光效率，ＮａＢｉ（ＷＯ４）２晶体的衰减为３ｎｓ，是闪烁晶体中最短者之一。     

Y3+:PbWO4晶体低剂量辐照行为研究

三价稀土离子(Ｌａ^３＋、Ｌｕ^３＋和Ｙ^３＋等)掺杂显著地提高了钨酸铅晶体的辐照硬度,但是部分Ｙ^３＋掺杂钨酸铅晶体表现出特殊的低剂量辐照行为,即光产额辐照后升高,并且辐照硬度对退火温度较敏感 本研究挑选了存在这一现象的Ｙ^３＋:ＰｂＷＯ_４晶体,测试不同温度的退火处理对晶体透过率、光产额和辐照硬度的关系,发现:辐照后光产额升高的现象同时存在于晶体的晶种端,而不是只集中在晶体顶端,并且和辐照前后晶体在４００~５００ｕｍ波段附近的透过率变化有关;生长态Ｙ^３＋:ＰＷＯ晶体中导致４３０ｕｍ吸收带的色心的稳定性很低,低剂量辐照对该色心有“漂白”作用,辐照剂量率加大则晶体表现出光产额的降低;分段晶体的系列退火实验解释了辐照硬度对退火温度较为敏感这一现象,为进一步深入研究提供了实验基础．     

Characterization of polysiloxane organic scintillators produced with different phenyl containing blends

Aiming at the fabrication of elastomeric organic scintillators for the detection of ionizing particles and neutrons with good light yield, mechanical robustness and radiation resistance, several samples of polysiloxane added with suitable amounts of fluorophores, such as 2,5-diphenyloxazole (PPO) and Lumogen Violet (LV), have been herein produced starting from either the copolymer polydiphenyldimethylsiloxane with 22 mol% of diphenyl groups or from blends of this precursor with different amounts of the homopolymer polymethylphenylsiloxane, thereby ultimately obtaining, after room temperature vulcanization (RTV), siloxane scintillators bearing different amounts of phenyl side groups. The scintillators have been characterized as for optical properties by excitation and fluorescence spectroscopy, while their performances as radiation detectors have been derived from light yield measurements upon irradiation with α particles. Ion beam-induced luminescence (IBIL) has been also applied using a proton beam of 2 MeV to compare the behavior of the different compositions by observing the in-situ degradation rate of the emitting species under ion irradiation. The samples and commercial scintillators (EJ-212 and EJ-200) used as a standard underwent heavy irradiation with γ-rays from a ⁶⁰Co source at different doses, up to 54 kGy. Then, the ex-situ light yield toward α particles for each scintillator was collected twice again: immediately after the irradiation stage and after one month, in order to characterize the stability and the radiation hardness of scintillators produced with the different blends.     

New scintillators discovered by high-throughput screening

We report the scintillation luminosities, decay times, and emission wavelengths for 19 Ce³⁺ activated scintillators, 18 Eu²⁺ activated scintillators, and 4 self-activated scintillators. Of these, 18 have not been previously reported either as phosphors or scintillators. Their luminosities range from 40,000 to under 1000 photons/MeV. While these scintillators may not have properties that make them top candidates for widespread use, their data will contribute to a deeper understanding of factors that limit scintillator performance.     

Perovskite: Scintillators,direct detectors,and X-ray imagers

Halide perovskites (HPs) are used in various applications, including solar cells, light-emitting diodes, lasers, and photodetectors. These materials have recently received a great deal of attention as high-energy radiation detectors and scintillators due to their excellent light yield, mobility-lifetime product (µτ), and X-ray sensitivity. In addition, due to their solution-processability and low cost, perovskite materials could be used to produce thick perovskite films across wide areas, allowing for low-dose X-ray imaging. Perovskite-based scintillators and detectors could eventually replace commercialized products like thallium‐doped cesium iodide (CsI:Tl) and amorphous silicon (Si). Here, we review all of the key properties of HPs, the relevant terminology necessary for radiation detection and scintillation, the physical mechanisms underlying their operation, the fabrication process, and perovskite crystals and thin-films of varying dimensionality used for high-energy radiation detection. We also cover the critical issues and solutions that HPs as detectors, scintillators, and imagers face.     

Modelling of composite neutron scintillators

Composite neutron scintillators consisting of neutron-insensitive fluorescent dopant particles (e.g. ZnS:Ag) embedded in a matrix material containing isotopes with high neutron cross sections that emit energetic charged particles (e.g. 6Li) are a popular method for neutron detection in a variety of applications. The size and volume doping fraction of the fluorescent dopant particles and the densities of both dopant particles and the matrix material determine the characteristics of the pulse-height spectrum of emitted light and the probability that capture of a neutron will result in scintillation. In this work, we characterise the effects of these parameters for ZnS:Ag particles in a lithiated glass matrix using a Monte Carlo simulation of composite neutron detectors that we have constructed.     

Photoluminescence and scintillation properties of Al(PO3)3–CsPO3–CsBr–CeBr3 glass scintillators

Scintillators, which are widely used as radiation detectors, are phosphors that release absorbed ionizing radiation energy as ultraviolet or visible light. Inorganic glass scintillators have several advantages over inorganic crystal scintillators, such as ease of fabrication and low costs. However, unlike inorganic crystals, which can emit up to tens of thousands of photons/MeV, inorganic glasses exhibit less than several hundred photons/MeV in most cases. Here, we studied an inorganic glass scintillator that exhibits a light yield of 2700 photons/MeV, which exceeds those of previous inorganic glass scintillators with high light yields of approximately 2000 photons/MeV. The density of this material is 3.28 g/cm³, which is relatively high among glass scintillators. Moreover, a fast scintillation decay with a decay time constant of 30.0 ns was obtained and is attributed to the 5d–4f transition of Ce³⁺. Thus, this glass is suitable for gamma- and X-ray detection, thereby expanding the practical applicability of inorganic glass scintillators.

     

Scintillation properties of SrF2 and SrF2-Ce3+ crystals

This Letter presents the results of measuring scintillation properties of pure SrF₂ crystals and crystals activated by various concentrations of Ce³⁺ ions. The light yield of these materials is compared to that of the known scintillators NaI-Tl and CaF₂-Eu²⁺. Strontium fluoride crystals activated with Ce³⁺ ions are found to be characterized by high light yield and to be promising materials for use in scintillation detectors employed for γ-ray well logging.     

稀土离子掺杂Gd2O2S闪烁陶瓷的研究进展

稀土离子掺杂Gd₂O₂S闪烁陶瓷是20世纪80年代以后发展的硫氧化物闪烁体。高密度和高热中子吸收截面的Gd₂O₂S基质具有高的X射线和热中子阻止能力, 稀土离子(Pr³⁺、Tb³⁺等)的掺杂使其表现出快衰减或高光产额等特性, 在闪烁领域的应用中占据着重要地位。硫氧化合物的组分控制一直是其合成过程中需要解决的关键问题, Gd₂O₂S材料的高熔点和S元素挥发严重的问题, 限制了高光学质量和优良闪烁性能单晶的制备, 因此陶瓷是Gd₂O₂S闪烁体的主要应用形式。颗粒小、粒径分布窄且低团聚的纯相Gd₂O₂S粉体是高质量闪烁陶瓷烧结的关键, 单纯提高烧结温度制备的Gd₂O₂S闪烁陶瓷会产生大量的硫空位和氧空位, 降低材料的闪烁性能。制备Gd₂O₂S闪烁陶瓷通常需要压力辅助烧结, 这种苛刻的制备条件提高了生产成本。本文介绍了闪烁体的闪烁机理及研究概况, 着重综述了Gd₂O₂S闪烁陶瓷的制备工艺、缺陷的解决方法以及在中子成像和医学X-CT上的研究现状及应用情况, 最后对全文进行总结并对Gd₂O₂S闪烁陶瓷发展前景进行了展望。     

核医学成像技术对无机闪烁材料的需求

介绍了目前正在使用的X－射线成像屏、X－CT和PET等核医学成像技术的原理及其探头对无机闪烁体的性能要求，展示了几种最有发展前景的无机闪烁晶体－－硅酸镥（LSO）、铝酸镥（LuAP）和钨酸铅晶体的研究现状和存在的问题。指出透明陶瓷闪烁体的出现是对传统闪烁晶体的一个挑战。     

掺Yb3+闪烁晶体的研究进展

掺Yb³⁺闪烁晶体是新近发展起来的一类闪烁体,有可能用于探测太阳中微子.本文简要介绍了掺Yb³⁺闪烁晶体的电荷迁移发光的机理以及基质晶体对温度猝灭与浓度猝灭的影响.综述了具有石榴石结构和钙钛矿结构的两类掺Yb³⁺闪烁晶体的研究进展,特别是Yb:YAG和Yb:YAP晶体的生长、闪烁性能以及应用前景.最后,对掺Yb³⁺闪烁晶体的未来研究方向做了展望.