A Study on the CdZnTe Array Detector

The CdZnTe array detector is a new type of semiconductor detector being rapidly developed in recent years. It possesses a high spatial resolution and a high energy resolution, and it can work at room temperatures. This paper describes the physical properties and working principle of the CdZnTe array detector, as well as the manufacturing technology, including the chip pretreatment, passivation, ohmic electrode preparation, array template selection, and array packaging technology (micro-interconnection). For evaluating the perfor-mance of the detector, the authors have developed successfully a 4 pixel×4 pixel CdZnTe array and an 8 pixel×8 pixel CdZnTe array (with the thicknesses of 5 mm and 2 mm, the pixel size of 2 mm×2 mm, and the gaps of 0.15 mm and 0.2 mm, respectively) in cooperation with the partner. A multi-channel electronic readout system based on the ASIC (Application Specific Integrated Circuit) chip is devel-oped independently for the charge measurement of the 4 pixel×4 pixel CdZnTe array. The energy spectra and corresponding energy resolutions of the 16 pixels are obtained with the ¹³⁷Cs radiative source, among them the best resolution is 4.8%@662 kev.     

Development of a new photon diffraction imaging system for diagnostic nuclear medicine

The objective of this project is to develop and construct an innovative imaging system for nuclear medicine and molecular imaging that uses photon diffraction and is capable of generating 1–2 mm spatial resolution images in two or three dimensions. The proposed imaging system would be capable of detecting radiopharmaceuticals that emit 100–200 keV gamma rays which are typically used in diagnostic nuclear medicine and in molecular imaging. The system is expected to be optimized for the 140.6 keV gamma ray from a Tc-99m source, which is frequently used in nuclear medicine. This new system will focus the incoming gamma rays in a manner analogous to a magnifying glass focusing sunlight into a small focal point on a detector's sensitive area. Focusing gamma rays through photon diffraction has already been demonstrated with the construction of a diffraction lens telescope for astrophysics and a scaled-down lens for medical imaging, both developed at Argonne National Laboratory (ANL). In addition, spatial resolutions of 3 mm have been achieved with a prototype medical lens. The proposed imaging system would be comprised of an array of photon diffraction lenses tuned to diffract a specific gamma ray energy (within 100–200 keV) emitted by a common source. The properties of photon diffraction make it possible to diffract only one specific gamma ray energy at a time, which significantly reduces scattering background. The system should be sufficiently sensitive to the detection of small concentrations of radioactivity that can reveal potential tumor sites at their initial stages of development. Moreover, the system's sensitivity would eliminate the need for re-injecting a patient with more radiopharmaceutical if this patient underwent a prior nuclear imaging scan. Detection of a tumor site at its inception could allow for an earlier initiation of treatment and wider treatment options, which can potentially improve the chances for cure.     

矿物包裹体的气、液相成分测定

矿物中包裹体温度、压力和气、液相成分的测定数据是阐明矿床成因、成矿物质来源、成矿物质化学条件和成矿元素运移方式等的重要地球化学参数。本文介绍了用载气热爆—气相色谱法测定气相成分(H_2、O_2、N_2、CH_4、CO、CO_2、H_2O)和用超声波提取液相成分,再用原子吸收分光光度计法和数字离子计法分别测定阳离子(K~+、Na~+、Ca~(2+)、Mg~(2+))、阴离子(F~-、Cl~-)。对实验装置、工作条件和分析步骤等本文均有叙述。并以石英标样,对实验结果作了初步讨论。其中对气相成分的提取,用载气热爆法代替真空热爆法可提高工作效率五倍。     

改良3D-WE-FLASH序列在关节软骨成像中的应用

目的:对附加水激发技术的3D-FLAsH序列进行优化,并与传统的频率预饱和脂肪抑制技术的3DIFLASH序列进行比较.方法:健康成年志愿者10人,扫描序列采用不同的脉冲重复时间(TR)、回波时间(TE)和翻转角度(FA)的3组3D-WE-FLASH序列和一组3D-FS-FLASH序列.在各扫描序列标准矢状位图像上测量膝关节软骨信噪比(sNR)、关节软骨与周围组织之间的对比度噪声比(CNR)和关节软骨与关节液体之间的对比度噪声比效率(CNca-fluidefficiency).采用重复测量资料的方差分析对量化数据进行分析.结果:SNca,CNRcafluid,CNRca-fat,CNRca-menlsus在序列4组均显著性高于序列1、2、3组;SNRcaCNRca-fluid,CNRca-fatCNRca-bone在序列2组显著性高于序列1、3组;CNRca-fluideff在序列2、4组之间无显著性差异.结论:经优化后的水激发3D-FLASH序列能够显著缩短扫描时间并达到理想的软骨成像效果.     

等效偏移距偏移方法在声波反射成像测井中的应用研究(英文)

声波反射成像测井能够获得井眼周围构造的重要信息,然而,由于接收到的反射波信号远小于井眼模式波、信噪比较低,且每次发射只有8道接收,因此应用常规的偏移成像处理方法成像效果不好。本文应用一种基于散射理论的等效偏移距偏移方法,对声波反射成像测井模拟数据及现场数据进行偏移处珲。结果表明,与常规叠后深度偏移方法相比,等效偏移距方法可以有效提高覆盖次数,对于低信噪比的声波反射测井资料可以获得较好的井旁构造成像效果。     

Localization of water bearing fractured zones in a hard rock area using integrated geophysical techniques in Andhra Pradesh,India

Knowledge of the existence of fracture zones, their extent, intensity and direction is very useful for assessing groundwater in hardrock regions and in this context geophysical methods are widely accepted as a powerful means of study. In the modern era of exploration, application of the Resistivity Imaging technique gives a new opportunity for groundwater study in hardrock regions. Exploration surveys were conducted at one of the important sites in Maheshwaram watershed, Andhra Pradesh, India with a multielectrode resistivity imaging system. To reduce the ambiguity of geophysical interpretation some complementary geophysical studies like ground Magnetic and VLF were also carried out.A number of 2D resistivity images were prepared in a grid pattern, which clearly show the weathered and fractured zones in different parts of the study area. With the help of all 2D profiles a quasi-3D image has been created, which indicates the orientation and extension of the fracture zone in a horizontal as well as vertical direction in the study area. Strong agreement exists among the anomalies identified using the ground magnetic, VLF and resistivity imaging methods. The litholog data available in the study area also helps to interpret geophysical results to find a potential groundwater bearing zone in that area.     

绳索取心钻杆超声波探伤方法分析研究

对绳索取心钻杆断裂的原因进行了分析,对超声波探伤绳索取心钻杆方法进行了研究,对具体探测方法、探测仪器和探伤过程进行了分析。对有效预判绳索取心钻杆断裂、降低孔内事故发生率和减少经济损失具有一定的现实意义。