基于高能γ源的CdZnTe成像探测器极化效应研究

应用第一类边界条件泊松方程,推导了碲锌镉(CdZnTe)探测器晶体内部电势分布,研究了CdZnTe探测器在¹³⁷Cs高能γ源成像探测过程中的极化效应。数值计算与实验结果表明：在低辐射注量率条件下,即CdZnTe晶体内部载流子电荷密度较低时,内部电势分布主要受外加偏压影响,晶体内部电势与偏压为线性关系,电场呈均匀分布。在高辐射注量率条件下,即晶体内部载流子电荷密度较高时,内部电势分布出现极化区域,电场分布发生扭曲,电子载流子向辐照区域外侧迁移,形成辐照中心无信号而辐照边缘区域仍有响应信号的极化探测图像。极化效应造成CdZnTe探测器探测性能严重退化,辐照边缘区域像素事件计数下降约70%。     

BGO探测器制冷保温系统的制作和应用

采用蒸汽压缩式制冷方法制作了BGO探测器真空保温系统,并探讨了温度对BGO探测器能量分辨率的影响.结果显示,使用该制冷保温系统能使探测器周围的温度保持在实验所要求的范围内,从而减小了温度对探测器的影响.     

高能X射线探测器射线串扰模拟研究

探测器的串扰噪声会对探测器的信噪比以及高能工业CT的图像质量产生很大的影响。本文利用EGSnrc程序模拟估算了CdWO4探测器模块的串扰噪声,并初步分析比较了影响探测器模块串扰噪声的各种因素。对在实际中选用和设计探测器模块有一定的指导意义,同时为利用软件修正探测器串扰噪声提供了理论计算参数。     

压水堆堆内中子探测器响应函数特性研究

中子探测器响应函数是中子探测器周边区域对其读数贡献的分布函数,是将反应堆物理数值模拟计算结果与探测器实际电流相结合的有效途径。本文对中子探测器响应函数的计算公式进行了推导,并采用蒙特卡罗方法计算堆内固定式中子探测器的响应函数。针对影响中子探测器响应函数的相关因素进行了数值分析,分析结果表明,对中子吸收特性影响较大的因素,如硼酸、控制棒、可燃毒物等,对中子探测器响应函数的影响较大,需在实际的反应堆监测中着重考虑,本文中未考虑的因素影响也可采用本文类似的方法进行研究分析。     

压水堆堆内中子探测器响应函数特性研究

中子探测器响应函数是中子探测器周边区域对其读数贡献的分布函数,是将反应堆物理数值模拟计算结果与探测器实际电流相结合的有效途径。本文对中子探测器响应函数的计算公式进行了推导,并采用蒙特卡罗方法计算堆内固定式中子探测器的响应函数。针对影响中子探测器响应函数的相关因素进行了数值分析,分析结果表明,对中子吸收特性影响较大的因素,如硼酸、控制棒、可燃毒物等,对中子探测器响应函数的影响较大,需在实际的反应堆监测中着重考虑,本文中未考虑的因素影响也可采用本文类似的方法进行研究分析。     

硅位置灵敏探测器

半导体位置灵敏探测器是探测带电粒子位置的一种探测器,它具有位置分辨率和能量分辨率高、线性好的优点。在核物理实验和研究工作中——鉴别粒子,角度校正,核极化测量,裂变碎片和重离子的测定以及衰变反冲物的角分布测量等方面得到了广泛的应用。国外研制这种器件的单位较多。目前已达到的水平为:在器件整个长度上满刻度的线性为1%;位置分辨率为0.1毫米;能量分辨率对5.486兆电子伏的α粒子半宽度为50千电子伏;几何尺寸为30×8,40×8,50×8毫米~2。我们所研制的硅位置灵敏探测器见图1。     

2H(d,n)3He核反应中子注量的伴随粒子法测量

^2H(d,n)^3He核反应单能中子源广泛应用于MeV中子的散射和极化实验。采用伴随粒子法测量中子注量，用Si半导体探测器测量^3He粒子，用0.8μm Al箔来屏蔽散射的d束，系统可很好地分辨^3He,d,T和p，可测d^ 束能量到165keV，测量结果与用NE213探测器的结果相比较，一致性好于97％。     

放射性惰性气体探测器模拟研究

利用蒙特卡罗程序研究了核电厂气载放射性监测通道中重要监测设备放射性惰性气体探测器的结构设计思路、性能评估,主要研究内容包括优化探测器结构、分析影响测量准确性的因素、分析探测器测量范围、探测器自检源活度及其对周围环境的影响,本文详细展示了模拟计算结果,并总结其反应规律,为放射性惰性气体探测器的研制提供了重要的数据参考和理论支持。     

BGO探测器制冷保温系统的制作和应用

采用蒸汽压缩式制冷方法制作了BGO探测器真空保温系统，并探讨了温度对BGO探测器能量分辨率的影响。结果显示，使用该制冷保温系统能使探测器周围的温度保持在实验所要求的范围内，从而减小了温度对探测器的影响。     

离子注入型与金硅面垒型半导体探测器温度特性比较

半导体探测器性能受温度影响较大,影响着辐射探测系统的稳定性和测量精度。本文设计了一个温度测试电路,通过温度测试实验分别得出了离子注入型和金硅面垒型半导体探测器的温度特性曲线。测试结果表明,离子注入型半导体探测器的温度特性明显优于金硅面垒型半导体探测器。本文的结果可为半导体探测器的使用、筛选提供参考。     

Capabilities of Mercuric Iodide as a Room Temperature X-Ray Detector

Measurement results obtained with HgI2 detectors at room temperature in the low energy x-ray region down to 2 keV are reported. The best resolution obtained is 548 e V for 5.9 keV x-rays, and the 2.01 keV phosphorous x-ray line has been resolved with a detector with an area of 14 mm2. The different noise sources of the detector-amplifier system are analysed and polarization effects in the detectors are discussed. The mercuric iodide crystals were grown from the vapour phase by gradient reversal techniques.     

Moisture proof columnar cesium iodide (CsI) layers for gasavalanche microdetectors

Cesium iodide columnar layers having a diameter of ≈3 μm, and wall spacing of ≈1 μm act as secondary electron emitters and can be used for detection of radiation: charged particles, X-rays and gamma rays. With a large enough electric field across the columnar layers, ≈400 μm in thickness, gas avalanche gain is evident when placed in a suitable gas, such as P10 or argon-ethane mixtures. The cesium iodide columns are damaged by ambient moisture. This damage can be prevented by evaporating protective layers of insoluble, low boiling point inorganic materials, such as mercuric iodide. Columnar layers with 20 nm coatings of mercuric iodide yield more than 30000 electrons on average when traversed by electrons from a ⁹⁰Sr beta source     

Preliminary Studies on Mercuric Iodide Soft-Gamma-Ray Detector

Tetragonal mercuric iodide single crystals were grown and applied to the fabrication of soft-gamma-ray detectors with high detection efficiencies and moderate energy resolutions. The studies included: 1) the dependency of single crystals grown by various techniques such as solution growth including recrystallization of the vapor transport grown crystal, vapor transport growth and temperature oscillation growth techniques on detector characteristics, 2) polarization effects, 3) electrical contacts problem, 4) fast-neutron-induced radiation damage and 5) linearity between pulse heights and energies. The detectors with various thicknesses from approximately 50 to 1000 microns were applied to the X-ray fluorescence analysis proved to be a very promising tool in this field for the linearity calibration and charge collection efficiencies examination of the detector of various thicknesses.     

碘化汞探测器及其对HL-1M装置中X射线辐射测量

本文叙述新研制的以高纯度碘化汞晶体为基片的低噪声、高探测效率、高计数率、较高能量分辨率，常温状态下运行的ＨｇＩ２半导体探测器的特点，以及特制的电荷灵敏前放和主放大器组成的探测系统对ＨＬ－１Ｍ托卡马克在欧姆加热、低杂波电流驱动、外加径向电场以及激光吹气掺杂等实验条件下，来自等离子体心部的硬Ｘ射线辐射进行测量，得到辐射强度和能谱随时间的变化等实验结果，并对实验结果作了初步的解释。     

Present Performances and Potential Applications of Mercuric Iodide Detectors

The need for room temperature detectors capable of high detection efficiency for x-ray and ?-ray spectroscopy has long been recognized. This has resulted in substantial work on potentially suitable high-Z semiconductors. Detectors made from mercuric iodide have proved to be the most attractive candidates, particularly for low-energy x-ray applications. Such detectors are now commercially available. Mercuric iodide exhibits the wide-band gap required for room temperature operation and the high atomic number (Z) required for efficient photons detection. However, in common with other II-VI compound semiconductors, poor hole collection results from deep hole traps. Fortunately, for low-energy x-rays incident on the negatively-biased contact, the signal is dominated by electron collection. Therefore in this case, very good energy resolution can sometimes be obtained, opening up the possibility of wide-ranging applications for x-ray fluorescence spectroscopy. Good resolution, long-term stability, and a lack of polarization effects all represent the objectives of work on these detectors; these factors and their control will be discussed here. The performance of recent detectors has been discussed elsewhere. The paper will focus on three aspects of development of HgI2 detectors: i) Methods of purification and crystal growing. Several methods are used and these will be discussed. ii) Fabrication of detectors. iii) Applications and performance of detectors. Mercuric iodide detectors are described here both from the point of view of fabrication methods and from the user's point of view. The paper highlights the performance achieved at different photon energies.     

10～150keV X射线碘化汞探测器阵列研制

碘化汞半导体探测器阵列具有低噪声水平、高探测效率、高计数率、较高的能量分辨率、常温下运行的特点,用它研制成功的5通道阵列因去掉体积庞大且费用昂贵的冷氮冷却系统很适合观察HL－1M托卡马克在各种放电条件下,超热电子和低能逃逸电子引起的其能量在10－150keV 范围内X射线辐射强度的变化及超热电子辐射的X射线能谱,并由此得到辅助加热时能量沉积的区域及超热电子的温度。     

High-purity titanium,zirconium, and hafnium in nuclear power

The use of high-purity (iodide) titanium, zirconium, and hafnium for obtaining building and absorbing materials for use in nuclear power is examined. The possibilities for iodide refining of these metals to remove impurities and the chemical composition, microstructure, and microhardness of iodide rods are presented. Regimes for chemical decontamination of raw materials and iodide refining of metals in commercial equipment are examined. It is shown that iodide refining makes it possible to use as raw materials the wastes and recyclables from metallurgical and rolled production of titanium, zirconium, and hafnium and to obtain from them under commercial conditions high-purity metals with multiple uses, including as components of a charge for smelting alloys to be used in nuclear power. Materials based on titanium, zirconium, and hafnium of consistent quality which are obtained using metal iodides will make it possible to extend the VVER service life to 60 years.     

Experimental study of retinoic acid on improving iodide uptake in MCF-7 breast cancer cells

The study aims to investigate the effect of retinoic acid on the iodide uptake of MCF-7 cells and its mechanism. The iodide uptake and expression of hNIS（human sodium/iodide symporter）mRNA in the breast cancer MCF-7 cells were compared individually before and after the intervention of all-trans retinoic acid （ATRA） with the iodide uptake assay and RT-PCR. The following results are obtained： （1） when treated with all-trans retinoic acid in the concentration of 1.0 μtmol/L, the capacity of iodide uptake of MCF-7 cells reached about 1.5 times of the basal state; （2） 12 h aftef the intervention of 1.0 μtmol/L ATRA, the hNISmRNA expression of the MCF-7 cells reached maximum. The study shows that all-trans retinoic acid has the effect to improve the iodide uptake of the MCF-7 cells and this effect may result from its up-regulation of the hNISmRNA expression.     

Transport and Deposition of Halide in Alkali Metal-Stainless Steel Systems, (III)

Solubility of sodium iodide in liquid sodium was determined over a temperature range of 350~650°C by using capsules of two different kinds.

Stainless steel capsule of short type loaded with 2~3.5g sodium and fragments of sodium iodide crystal was put in a pair of holders and heated under an uniform temperature distribution in a vertical electric furnace. Stainless steel capsule of long type loaded with 20 g sodium and powders of the iodide was heated at its upper part in the furnace and cooled at its bottom to establish a large temperature gradient along the capsule tube. After a given term of heating, the iodide was fixed in solidified sodium by quick quenching of these capsules.

The iodide solubility data measured by using the capsules are in good agreement with the data reported by Miyahara, Power Reactor and Nuclear Fuel Development Corp. (PNC). It is not observed in the measurement that the iodide is enriched at free surface of the liquid sodium and forms particles in the solution; these were thought of as reasons why PNC expressions of the solubility are about 10 times as large as Allan's expression.     

A Proposal for Detecting Anomaly with Use of Autoregressive Parameter of Innovation Series

Deposition behavior and solubility of sodium iodide in sodium-stainless steel system was studied with using capsules placed vertically under a large temperature gradient.

The stainless steel capsule loaded with 20 g of reactor grade sodium containing sodium iodide was heated at its upper part and cooled at its bottom to establish the temperature gradient along the capsule tube and to precipitate and accumulate the iodide onto the capsule bottom, and was quenched to fix the Iodide in solidified sodium after the diffusing run. Distributions of the iodide in the sodium in radial and axial directions were obtained as a function of temperature during the run. A partition value of the iodide between the core sodium and its periphery was calculated from the radial distribution in the sample in unsaturated regions. The solubility of the iodide in sodium was determined from the axial distribution in the core sodium samples.

Heat of adsorption obtained from the partition value and the solubility determined with this method are in reasonable agreement respectively with the data reported by Allan.