用于雷达的16路AD变换及采集系统

模数转换已成为计算机在各个研究和应用领域中的不可缺少的手段之一，本文介绍一个１６通道的模数转换及数据采集系统，该系统用于雷达之中，要求１６个通道有较高的一致性，并与ＩＢＭ２８６／３８６微机接口。     

一个16通道程控时间延尺的VME插件

本文介绍了一人１６通道的程控时间延迟ＶＭＥ插件，该插件将用以正在日本高能物理国家实验室建造的ＢＥＬＬＥ探测器的触发系统，其延迟信号的时间晃动的均方根值小于３００ｐｓ。     

一个 16 通道程控时间延迟的 VME 插件

本文介绍了一个１６通道的程控时间延迟ＶＭＥ插件。该插件将用以正在日本高能物理国家实验室建造的ＢＥＬＬＥ探测器的触发系统，其延迟信号的时间晃动的均方根值小于３００ｐｓ。     

低功耗海洋地震勘探数据采集系统设计

针对海洋地震勘探,设计了一种低功耗数据采集系统。该系统以FPGA为控制核心,采用低功耗24位□-型AD7779模数转换芯片完成多路信号采集,通过USB总线与上位机进行数据交换。同时,系统使用高精度DAC芯片设计了自检电路,用于采集通道性能与质量检测。测试结果表明:系统性能指标与功耗水平均达到了设计目标,满足海洋地震勘探的需求。     

16通道剂量率在线检测系统的软硬件设计

介绍了一种16通道剂量率在线检测系统的软硬件设计.探测器输出的数据经过前端的放大和模数转换后,经FPGA传至微处理器中,进行低频滤波、转换计算、温度补偿、台阶扣除等处理,有效地修正了温度波动带来的暗电流变化,得到了足够精确的瞬时剂量率值.     

微结构气体探测器多通道高速读出系统研制

本文设计并实测了用于多通道微结构气体探测器信号读出的512通道电子学系统。该系统以Spartan-6 FPGA作为控制和数据处理核心,使用4通道ADC芯片对4片APV25芯片的输出信号进行同步模数转换,经千兆以太网发送命令和传输数据,计算机端则以双线程分别接收和发送数据。实测输入电容低于200 pF时,系统噪声低于2000e,有效电荷输入范围为±20 fC,12 fC以下时线性良好。经长时间测试,系统稳定可靠,千兆网数据传输速率可达940 Mb/s。单片APV25工作时,连续触发率可达APV25上限285 kHz,4片时则为134 kHz。在实际应用于GEM探测器α射线成像实验中取得了较好的成像结果。     

16通道高分辨CAMAC时间数字转换器

介绍一种１６通道高分辨ＣＡＭＡＣ时间数字转换器组件,具有１２位动态范围,其最小时间分辨达２６ｐｓ,１６个通道的总变换时间仅１５μｓ。该组件采用ＣＯＭＭＯＮＳＴＡＲＴ模式,１６个独立的ＳＴＯＰ。该且件有两种读出方式;随机读出和稀疏扫描读出方式。     

基于光电二极管阵列的二维成像数据采集系统研究

本文研制了—套基于多像素光子计数器阵列(MPPC)的H_α辐射光二维高速成像系统~([1]),通过对微弱H_α辐射光的成形放大、模数转换和数据处理,实现了128通道高达1Mfps的二维成像系统。该系统用于研究托卡马克聚变实验中的加料过程,通过测量氘分子同等离子体相互作用产生的H_α辐射光的空间分布图像,获得超声分子柬的密度、空间分布等参数随时间的演化过程,是适用于托卡马克聚变装置的重要诊断技术之一。     

窄矩形通道内Ledinegg不稳定性实验研究

为研究窄矩形通道Ledinegg不稳定性，分析影响系统Ledinegg不稳定性的主要因素，对窄矩形通道进行了一系列的实验研究和数学理论推导。实验表明：随热流密度的增加或系统压强的减小，窄矩形通道内部特征曲线负斜率区斜率变小。此斜率越小，系统发生不稳定的概率越大，且流量漂移的波动振幅越大；与常规通道不同，过冷度对窄矩形通道Ledinegg不稳定性的影响程度很小。在忽略窄矩形通道内的加速压降和重力压降，仅考虑摩擦压降的情况下，推导出窄矩形通道内部特征曲线的数学关系式，给出了系统达到稳定的数学条件。     

SFC引出磁通道

在原有的ＨＩＲＦＬＳＦＣ引出系统基础上，设计了两个无线圈磁通道。一个通道将ＳＦＣ边缘场改变成正梯度的线性分布场，使引出束流在径向聚焦；另一个通道屏蔽一部分边缘场，使引出束向大半径方向偏转；此外，还设计了１２０°对称的假磁通道，以平衡磁通道给ＳＦＣ带来的一次谐波扰动场。实际的测磁结果表明，磁通道达到了设计的理论要求。此设计完善了ＳＦＣ束流引出系统。     

Analysis of the desorption of clusters of intact amino acid valine molecules induced by energetic monoatomic and cluster ions

The experiments on the desorption of intact valine molecules and (nM + H)⁺ clusters are analyzed and a ln(Y/S_e) − 1/S_e scaling is found where Y, and S_e are the sputtering yield and the electronic stopping power, respectively. The scaling can be derived with the assumption of a thermal activation mechanism. In the plots the desorption is a uniform process without threshold value of S_e, having different activation energies U in various charge states. The desorption of (nM + H)⁺ clusters proceeds in n steps with varying Coulomb contributions. Irradiation with C₁₀ and C₆₀ ions leads to higher Y, however, the increment is reduced with the increase of S_e.     

2 MeV Si ion implantation damage in relaxed Si1−xGex

The damage produced by implanting, at room temperature, 3 μm thick relaxed Si_1−xGe_x layers with 2 MeV Si⁺ ions has been measured as a function of Ge content (x = 0.04, 0.13, 0.24 or 0.36) and Si dose in the dose range 10¹⁰–10¹⁵ cm⁻². The accumulation of damage with increasing dose has been studied as a function of Ge content by Rutherford Backscattering Spectrometry, Optical Reflectivity Depth Profiling and Transmission Electron Microscopy and an increased damage efficiency in Si_1−xGe_x with increasing x is observed. The characteristics of implantation-induced defects have been investigated by Electron Paramagnetic Resonance. The results are discussed in the context of a model of the damage process in SiGe.     

The Electronegativity Analysis of c-C4F8 as a Potential Insulation Substitute of SF6

The density distributions related to gas electronegativity for c-C₄F₈ gas, including negative ion, electron number and electron energy densities in the discharge process, are derived theoretically in both plane-to-plane and point-to-plane electrode geometries. These calculations have been performed through the Boltzmann equation in the condition of a steady-state Townsend (SST) experiment and a fluid model in the condition of both uniform and non-uniform electric fields. The electronegativity coefficients a = n−/ne of c-C₄F₈ and SF₆ are compared to further describe the electron affinity of c-C₄F₈. The result shows that c-C₄F₈ represents an obvious electron-attachment performance in the discharge process. However, c-C₄F₈ still has much weaker gas electronegativity than SF₆, whose electronegativity coe?cient is lower than that of SF₆ by at least three orders of magnitude.     

Diamagnetic measurement on HT-7 superconducting tokamak

Diamagnetic measurement is a basic diagnostics on tokamak. Some important plasma parameters such as plasma energy and betap β_p can be obtained from this measurement. For most case, diamagnetic flux ΔΦ is extremely smaller than toroidal flux Φ (ΔΦ/Φ − 10⁻⁴). Therefore we have to use techniques that allow measurement to better than 1 part in 104 to get 10% accuracy in value of β_p. Using a compensation coil is a typical technique to improve the signal to noise ratio. In this paper the design of diamagnetic diagnostics system for HT-7 superconducting tokamak device is introduced and some experimental results of plasma energy and β_p are given in different plasma discharges.     

阳离子有序相Ce2Zr2O7.97的石墨还原制备及其结构表征

采用石墨还原法探索了CeO₂-ZrO₂二元体系在不同还原温度、还原时间条件下的物相组成及结构,借助X射线衍射、红外振动光谱等手段对还原样品进行了物相表征及结构分析。实验结果表明：通过石墨还原能在较低温度（T_red＝1050 ℃）、较短时间（t＝24 h）内合成纯相Ce₂Zr₂O_7.97,较传统先还原（95%Ar+5%H₂,T_red≥1400℃,t＞48 h）后氧化（O₂或空气气氛）工艺更简单经济;Ce₂Zr₂O_7.97相能在1050～1300 ℃、24～72 h还原条件下稳定存在并保留至室温而不发生相分解,其机制可能归因于石墨所形成的弱还原环境;Ce₂Zr₂O_7.97相拥有与烧绿石Ce₂Zr₂O₇相近的有序阳离子亚晶胞结构,但由于其氧空位（O3、O4、O11）被大部分氧离子所填充,导致该相结构对称性降低。本文提出的石墨还原法制备富氧相Ce₂Zr₂O_7.97有望成为一种较传统制备工艺更简单经济的新方法,而Ce₂Zr₂O_7.97相能在还原气氛中稳定存在,可为An₂Zr₂O_7+x固化体的存放环境提供借鉴和参考。     

Channeling of low energy light and heavy ions in single-wall nanotubes

The Monte Carlo simulation program has been used to study low energy channeling in the single-wall nanotube and its rope, in comparisons between beam sizes and between light (He) and heavy (Ar) ions. The simulation mainly shows that the critical angle Ψ_C = 48 E^−1/2 (E is incident energy) for the He (light) ion channeling but Ψ_C = 18 E^−1/2 for the Ar (heavy) ion channeling, in the (17,0) zigzag single-wall nanotube. Thus, it might be found in the simulation that Ψ_C strongly depends on the ion mass.     

Role de l''iodure de cesium sur le developpement des reactions combustible-gaine

TEM of thin foils taken from irradiated fuel element ((UPu)O_2−x fuel in type 316 stainless steel cladding) shows precipitates rich in iron and chromium in the fuel, together with a reduction of chromium content in the cladding. We have undertaken simulation experiments out-of-pile to study the compatibility, both isothermally and in thermal gradients, of the steel/CsI and steel/(CsI + UO ₂) systems, making use of metallography, X-ray diffraction and microprobe analysis, with a view to gaining a better understanding of the reactions at the fuel cladding interface in reactor service. The results of the simulation and reactor-irradiation experiments have enabled us to prepare a transport mechanism in the gas phase, of van Arkel type, involving stainsless steel (at low temperature), (UPu)O_2±x (at high temperature) caesium iodide serving as vector. This transport mechanism which essentially involves displacement of manganese, chromium and iron from cold zones to hot zones, is possible only in the presence of an oxygen source (and the mixed oxide, (UPu)O_2±x, in particular).     

99Tcm-3PRGD2 SPECT显像用于胰腺癌荷瘤裸鼠动物实验及临床转化研究

本工作探讨了新型示踪剂⁹⁹Tc^m-HYNIC-3PEG₄-E［c(RGDfK)］₂（⁹⁹Tc^m-3PRGD₂）用于胰腺癌的诊断价值及临床转化可行性。用免疫组化实验测定PANC-1胰腺癌细胞以及肿瘤组织中的整合素α_vβ₃的表达。将PANC-1胰腺癌细胞种植于BALB/c裸鼠肩部,建立合格的动物模型。以联肼尼克酰胺(HYNIC)作为双功能连接剂,采用无亚锡一步法制备⁹⁹Tc^m-3PRGD₂。在0.5~6.0 h,每隔0.5 h行一次荷瘤鼠⁹⁹Tc^m-3PRGD₂全身平面显像,观察全身分布情况,于肿瘤及健侧勾画感兴趣区（ROI, region of interest）,计算肿瘤与本底(T/NT)的比值。对6例胰腺肿瘤患者行99Tcm-3PRGD₂单光子发射的计算机断层显像（SPECT）,评估对胰腺癌的检出率。结果表明：PANC-1胰腺癌细胞以及肿瘤组织中高表达整合素α_vβ₃。⁹⁹Tc^m-3PRGD2标记率大于99%。荷瘤鼠显像显示肿瘤对示踪剂摄取好,0.5 h时即可见肿瘤显影,1.5 h时T/NT达最大值,6.0 h时肿瘤仍可清晰显示。⁹⁹Tc^m-3PRGD₂ SPECT显像可检出6例患者的胰腺肿瘤原发灶和肝转移灶,检出率为100%。⁹⁹Tc^m-3PRGD₂是一种安全有效的示踪剂,特异性结合整合素α_vβ₃,⁹⁹Tc^m-3PRGD₂ SPECT对胰腺癌的临床诊断具有潜在的应用前景。     

超顺磁性氧化铁纳米粒子SPION-dopa-PEG-DOTA/RGD的~(64)Cu标记、纯化及生物分布

对64 Cu标记超顺磁性氧化铁纳米粒子SPION-dopa-PEG-DOTA/RGD的标记及纯化条件进行探索,并根据其在小鼠体内的生物分布研究结果,揭示其主要的代谢方式。通过对标记过程中配体浓度、温度、时间等条件的改变,探究64 Cu标记SPION-dopa-PEG-DOTA/RGD的最优条件;并采用二乙基三胺五乙酸(DTPA)螯合标记混合物中游离的64 Cu,经PD-10柱纯化后得到放化纯较高的标记物;采用快速薄层层析法测定标记物的标记率和放化纯;分别测定了标记物的体外稳定性和脂水分配系数;将64 Cu标记的氧化铁纳米粒子经尾静脉注射到正常鼠的体内,分别于注射后不同时间点取各脏器,称重、测定放射性计数率,计算每克组织的百分注射剂量率(%ID/g)。经条件优化后得到的64 Cu-SPION-dopa-PEG-DOTA/RGD的标记率为63%,PD-10柱纯化后放化纯大于95%,水溶性良好,且放化纯在标记后12h内在磷酸盐缓冲液和人血清白蛋白中表现出了较高的稳定性;动物体内生物分布实验显示,该标记物在小鼠体内主要经肝脏代谢,肾脏排泄,血液中放射性清除较快。该标记物可用于后续的PET/MRI双模态显像的研究。     

Heavy ion irradiation effects in the rare-earth sesquioxide Dy2O3

Polycrystalline pellets of the rare-earth sesquioxide Dy₂O₃ with cubic C-type rare-earth structure were irradiated with 300 keV Kr²⁺ ions at fluences up to 5 × 10²⁰ Kr/m² at cryogenic temperature. Irradiation-induced microstructural evolution is characterized using grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). In previous work, we found a phase transformation from a cubic, C-type to a monoclinic, B-type (C2/m) rare-earth structure in Dy₂O₃ during Kr²⁺ ion irradiation at a fluence of less than 1 × 10²⁰ Kr/m². In this study, we find that the crystal structure of the top and middle regions of the implanted layer transform to a hexagonal, H-type (P6₃/mmc) rare-earth structure when the irradiation fluence is increased to 5 × 10²⁰ Kr/m²; the bottom of the implanted layer, on the other hand, remains in a monoclinic phase. The irradiation dose dependence of the C-to-B-to-H phase transformation observed in Dy₂O₃ appears to be closely related to the temperature and pressure dependence of the phases observed in the phase diagram. These transformations are also accompanied by a decrease in molecular volume (or density increase) of approximately 9% and 8%, respectively, which is an unusual radiation damage behavior.