无机闪烁晶体在我国的发展史

NaI(TI)探测器是典型的闪烁体辐射探测器,其探测过程涉及辐射能量沉积、可见光信号产生与输运、光电转换与信号处理等物理过程。首先利用蒙特卡罗方法、Birks公式及射线追迹程序,开展了射线粒子在晶体中转为可见光输出过程的计算分析,并结合光电倍增管和信号处理电路的指标参数进行模拟仿真,得出探测器最终输出的脉冲电压信号参数;然后,在¹³⁷Cs源辐射场中采用Φ50 mm×50 mm NaI(TI)晶体耦合光电倍增管开展实验验证,实验测得探测器输出脉冲信号的上升/下降时间比为0.39,与模拟计算数值0.36相比,相差约7.69%,表明模拟计算模型的输出结果与实测数据基本符合,初步证明了论文的模拟计算模型及计算分析过程的正确性。论文提出的方法,对于深入理解辐射粒子激发的荧光可见光在晶体闪烁体中的传输规律和闪烁体辐射探测器系统的优化设计,具有一定参考意义。

     

香港大学在束伽玛谱学研究与新一代伽玛探测器阵列(英文)

探索原子核的壳层演化,验证奇特核的幻数结构是香港大学核物理研究的重要方向。目前,科研团队利用在束伽玛谱学技术已经研究了30Ne的N=20幻数消失和78Ni（Z=28,N=50）附近原子核的双幻数结构,而即将开展的53,56Ca在束伽玛谱学实验会对新幻数N=34的定量研究,以及到N=40核的壳层演化提供重要的数据。下一步的研究目标是探索100Sn（N=Z=50）的奇特结构,特别是研究它的第一个2+激发态与其邻近原子核的低激发态性质。100Sn处于质子滴线以及核天体快质子俘获路径上,因此,它的幻数结构及其临近原子核单粒子性能研究将会极大增强对核力和核合成机制的认识。为了进一步提高物理实验统计,香港大学在数量上增加了30% NaI（Tl）晶体从而全面升级了DALI2伽玛探测阵列。此外,为了探索远离稳定线核区的新物理,开展更高精度在束伽玛谱学实验,香港大学与中国科学院近代物理研究所、中国原子能科学研究院计划合作研制基于溴化镧晶体的新一代伽玛探测器阵列。这套阵列主要在兰州重离子加速器（HIRFL）和将来建成的强流重离子加速器（HIAF）等大科学装置上开展实验,从而在奇特核研究方面取得大量重要的成果,促进科研人员全面认识、理解核力以及天体核合成过程。Exploring the evolution of shell closures and examining the magicity of extremely exotic nuclei are the main research interests of HKU (University of Hong Kong) experimental nuclear physics group. The group has employed in-beam gamma-ray spectroscopy technique to investigate the vanishing of N=20 magicity in 30Ne (N=20) and the strong magicity in nuclei around 78Ni (Z=28, N=50). The approved future's experiment on spectroscopy of 53,56Ca, proposed by HKU, will give quantitative information for the \"magic index\" of N=34 and shell evolution toward N=40. The next goal is to investigate the structure of 100Sn (N=Z=50), particularly the energy of the first 2+ state, and the low-lying states in the neighboring nuclei. 100Sn lies on the proton drip-line and on the astrophysical rp-process path. Characterizing the magicity of 100Sn and the nature of single-particle states in its neighboring nuclei is therefore essential to the fundamental understanding of nuclear forces and nucleo-synthesis. To significantly increase the data statistics for our physics goals, HKU group has prepared the upgrade of gamma-ray spectrometer DALI2 with 30% more NaI(Tl) detectors integrated into a new array configuration. On the other hand, next significant insights into the structure of nuclei would require new gamma-ray detection array capable for higher precision gamma-ray spectroscopy. HKU group in collaboration with IMP and CIAE therefore proposes to construct a new-generation gamma-ray detection array based on the novel scintillator LaBr₃(Ce) to explore the new physics in nuclei far from the valley of stability. Utilizing the radioactive beams at the Chinese large-scale facilities such as the Heavy Ion Research Facility in Lanzhou (HIRFL) in IMP and the future's High Intensity heavy-ion Accelerator Facility (HIAF), this novel LaBr₃(Ce) array would lead to a significant boost to the frontiers of exotic-nuclei research, which will guide scientists towards the comprehensive and even beyond-traditional understanding of nuclear forces and nucleosynthesis.     

γ射线探测器响应函数的JMCT模拟计算

采用自主研发的JMCT软件,模拟计算了射线在NaI闪烁探测器中的响应函数。JMCT模拟计算了探测过程中所有的、完整的光子-电子耦合输运过程。其模拟计算的射线能量沉积谱、探测器响应函数,与MCNP的计算结果符合得非常好,与Berger解析法计算的结果也基本符合,表明JMCT软件可以在探测器响应函数方面得到满意的结果,JMCT将在实验核物理、核分析技术应用等方面发挥越来越重要的作用。     

STUDY OF THE CORRELATION BETWEEN POWER DEPOSITION OF THE LOWER HYBRID WAVES AND THE HARD X-RAY RADIATION ON HT-7 TOKAMAK

A seven-channel NaI(Tl) detector array installed on an HT-7 superconducting tokamak has been used to detect the hard X-ray (E_hν>20keV) emitted from the plasma. The physical mechanism of the lower hybrid waves propagating and absorbed in the plasma is investigated by the measurement of hard X-ray radial profile at different discharge parameters.     

A multi NaI(Tl) detector array for medium energyγ-ray spectroscopy

An array of seven hexagonal NaI(Tl) detectors has been set up for measuringγ-ray spectra in the energy region 5 MeV ≤E _γ ≤ 40 MeV with good accuracy. This is in contrast to earlier set ups which mostly used one large sized (about 10 inchesφ × 15 inches long)NaI(Tl) detector. This set up has been made for the study ofγ decay of GDR based on high spin states and ultra-dipole radiations. The array has been provided with the following features: a) TOF discrimination against neutrons, b) pile up detection and elimination, c) active and passive shielding to cut down background and d) an array of trigger counters for multiplicity dependence measurements. The well known program EGS4 has been used to determine the response of the array forγ-rays in the energy region 5–40 MeV and several test measurements have been carried out to confirm the validity of the calculated response functions. Some typicalγ-ray spectra fromα and¹⁶O induced reactions measured at VECC, Calcutta and Pelletron accelerator at TIFR are also shown.     

MEGHNAD — A multi element detector array for heavy ion collision studies

In the coming decade, the expanding field of experimental nuclear physics in our country is going to see a quantum leap in research and developmental activities with new accelerator facilities like the variable energy cyclotron with ECR heavy ion source, the upcoming K-500 superconducting cyclotron, both at VECC, Calcutta, and the superconducting linac boosters at both the Pelletron Accelerator Facilities at TIFR, Mumbai and NSC, New Delhi. When heavy ion beam available from such machines fall on a target and undergo collision, very rich and often pristine fields of research open up. In order to carry on such activities, we have taken up a project to build a multi element gamma, heavy ion and neutron array of detectors (MEGHNAD) to detect and study the properties of a wide variety of particles like neutrons, protons, light mass clusters, massive ejected fragments, and gamma rays with good solid angle coverage and efficiency. Design of the detector array, performance of the prototype detector and brief outline of the research programme to be undertaken with the detector array will be discussed. For MEGHNAD Project.     

PET探测器技术的新进展

PET设备中探测器的研发, 一直是很活跃且具有高创新性的领域。 提高现有基于闪烁晶体探测器的性能, 研究适用于多模式成像设备（PET/CT和PET/MRI）的新型探测器, 满足TOF和DOI技术的需求并促进其发展应用, 构成PET探测器的几个主要研究方向。 介绍了PET探测器在闪烁晶体、 光电探测器和半导体探测器等方面的最新进展, 指出未来最有潜力的探测器设计方案。 The research on PET detector is a very active and highly innovative field. The main research interests of PET detector include improving performances of scintillation crystal detectors, investigating new detectors being suitable for multimodality imaging (e.g., PET/CT and PET/MRI), meeting needs of TOF and DOI technologies in order to promote their development and application. In this paper, new developments in PET detector technology about scintillation crystal, photodetector and semiconductor detector are introduced and the most potential detector design scheme in the future is brought forward.     

Measurement of radiation dose at the north interaction point of BEPCⅡ

The technique details for measuring radiation dose are expounded.The results of gamma and neutron radiation levels are presented and the corresponding radiation shielding is discussed based on the simplified estimation.In addition, the photon radiation level move as background for future experiments is measured by a NaI(T1) detector.     

用于中能重离子反应测量的塑料闪烁探测器阵列

描述了用于中能(10-100MeV/u)重离子核反应前角度(5°≤θ≤20°)测量的36单元phoswich闪烁探测器阵列.每个phoswich探测器单元由1mm厚的快塑料闪烁体NE102A和100mm厚的慢塑料闪烁体NE115组成,用传统的快、慢门控制的QDC积分方法,对Z=1-20范围的碎片得到了好的粒子鉴别,其粒子分辨能力Z/△Z～45.     

YAG:Ce and YAP:Ce – Suitable Fast Detectors for Transmission Mössbauer Spectroscopy

Yttrium aluminum garnet and perovskite activated by cerium are fast mechanically and chemically resistant scintillation materials. Their mechanical properties enable easy and precise machining. Both scintillation materials have a decay time shorter than 100 ns and, therefore, are suitable to use for high counting rates. The luminescence maximum of YAP:Ce and YAG:Ce are 360 and 550 nm, respectively. Their luminescence bands correspond with the sensitivity spectral range of the most widely used photomultipliers. Moreover, the semiconductor light detectors can be used with YAG:Ce scintillation crystals. Theoretical and experimental comparative analysis of characteristics for both YAP:Ce and YAG:Ce detectors and good experience over relatively long periods of using these detectors allow us to draw a conclusion regarding their unconditional advantages over other commonly used detectors for transmission Mössbauer spectroscopy. The considerable improvement in data production enhances the capabilities of Mössbauer spectroscopy as a research and analytical tool.     

Growth of high quality Ce~(3 ):YAP and (Ce~(3 ) Nd~(3 )): YAP single crystals

The effect of melt pretreatment of Ce~(3 ): YAP and (Ce~(3 ) Nd~(3 )): YAP and their growth ambient gases on the quality of the crystals are described. Firstly, a superheating pretreatment of YAP melt is adopted in a nitrogen atmosphere containing a little oxygen to eliminate carbon; then the YAP melt is superheated in a reduction atmosphere to fully reduce Ce~(4 ) ions into Ce~(3 ) ions in the melt. Finally, in a growth atmosphere of pure nitrogen, high quality Ce~(3 ): YAP and (Ce~(3 ) Nd~(3 )): YAP single crystals with high Ce~(3 ) concentration with only few light scattering centers were grown.     

Study of radiation background at the north crossing point of the BEPC in collision mode

Understanding the radiation background at the north crossing point (NCP) in the tunnel of BEPCII is crucial for the performance safety of the High Purity Germanium (HPGe) detector, and in turn of great significance for long-term stable running of the energy measurement system. Therefore, as the first step, a NaI(Tl) detector is constructed to continuously measure the radiation level of photons as background for future experiments. Furthermore, gamma and neutron dosimeters are utilized to explore the radiati...     

用闪烁探测器验证放射性衰变的统计规律

介绍了用闪烁探测器代替盖革-米勒计数管验证放射性衰变中的统计规律,为缺少G-M计数管的实验室提供一种新的实验方法.     

国产CsI(TI)晶体辐照损伤实验研究

研究了ＣｓＩ（ＴＩ）晶体在１．３ＧｅＶｅ－束形成的电磁辐射场和６０Ｃｏγ辐射场照射后的辐照损伤，测量了晶体光输出和透射率的变化，以及辐射损伤的自然恢复和加热恢复效应。     

溴化镧探测器时间分辨率的测量

用60 Coγ源和搭建的电子学测量系统,测量了自制塑料闪烁探测器、3英寸的溴化镧探测器和电子学系统的时间分辨率,得到了圣戈班公司生产的3英寸溴化镧探测器的时间分辨率为(283.2±0.9)ps.     

Be(d,n)反应中子源能谱测量及应用

利用中子飞行时间技术和BC501A液体闪烁探测器的粒子分辨特性,测量了0°方向、20 MeV氘束轰击厚金属铍靶反应产生的中子源能谱,测量的中子能谱范围为0.7～25.0 MeV。在60°方向放置芪晶体闪烁探测器,由刻度好的BC501A液体闪烁探测器归一校正后,用于中子源强度监测。利用Be(d, n) 反应中子源,采用单粒子灵敏度标定方法,实验标定了0.75~15.75 MeV能量范围内的薄膜闪烁探测器中子能量响应曲线,实验结果与蒙特卡罗模拟计算结果在8%的不确定度范围内一致。     

用于脉冲n/γ混合场γ强度测量的ICI探测器

研制成功一种基于康普顿效应, 用于脉冲裂变n/γ混合场γ强度绝对测量的新型辐射探测器—ICI(绝缘体－导体－绝缘体)探测器. 除具有现有真空康普顿和介质康普顿探测器时间响应快、线性电流大、抗辐射干扰能力强等优点外,该探测器从结构上抑制了真空康普顿在快脉冲γ测量中的前后负冲信号, 并且工作时不需要高真空, 而γ灵敏度却与同尺寸介质康普顿探测器相当. 由于其探测灵敏介质厚度小于2mm, 因而在群脉冲辐射探测中, 不会显著影响后续和周围探测器的测量环境, 是一种探测脉冲γ射线较理想的探测器.