动态偏置频率对X射线总剂量效应的影响

辐射偏置条件是影响MOSFET(Metal Oxide Silicon Field Effect Transistor)总剂量辐射效应的主要因素之一,因为辐射时栅氧化层中电荷的产生、传输与俘获都与辐射偏置有关.本文采用10 keV X射线对MOSFET在不同频率的动态偏置条件下进行总剂量辐射,分析了MOSFET辐照前后的阈值电压的漂移量和辐射感生电荷对阈值电压的影响.实验结果表明,动态偏置频率越高,辐射对MOSFET电特性的影响越小,产生的辐射感生电荷越少.     

SRAM辐射效应测试装置的研制与应用

SRAM辐射效应测试装置由主机和下位计算机测试板构成,可在多种辐射源下进行SRAM单粒子翻转、单粒子锁定等实验.介绍了SRAM辐射效应测试装置的硬件、软件构成及有关测试技术.利用该装置在激光辐射效应实验装置及HI-13串列加速器上成功地进行了SRAM的辐射效应实验.通过对SRAM芯片电流的检测,断电保护解决了在SRAM实验过程中SRAM芯片的损坏问题.     

SiC MOSFET单粒子效应研究现状

伴随核能与空间技术的快速发展,SiC MOSFET等高压大功率器件的应用不断增加,其因环境中的高能粒子辐射所引起的单粒子效应问题（如单粒子烧毁、单粒子栅击穿等）也逐渐凸显。为全面深入认识该问题,首先,论证了SiC MOSFET的优势特性,及其在辐射应用中面临的关键问题。然后,整理了目前国内外关于SiC MOSFET单粒子效应的模拟计算、辐照实验及相应研究成果,总结了在SiC MOSFET单粒子效应研究中的主要关注点,并分析了SiC MOSFET单粒子效应敏感性较高的原因。最后,基于目前SiC MOSFET单粒子效应研究中仍存在的问题,展望了未来可重点关注的研究方向。通过系统总结国内外SiC MOSFET单粒子效应研究进展,希望能为研究SiC MOSFET单粒子效应物理机制以及改进其抗单粒子效应加固技术提供有价值的参考。     

应用于空间系统的Power MOSFET辐射响应特性

为给金属氧化物半导体场效应功率管（Power MOSFET）在航天系统中的应用提供辐照数据基础和依据。用60^Co源对将应用于空间系统的两种Power MOSFET进行了不同总剂量的辐照实验。从微观氧化物陷阱电荷和界面态的辐射感生角度，分析了Power MOSFET器件在60^Co γ，射线辐射下的总剂量和剂量率效应以及辐照后70℃退火特性。试验表明与N沟道Power MOSFET相比，P沟道Power MOSFET可能更适合空间应用。     

功率MOSFET器件单粒子烧毁252Cf源模拟试验研究

本工作涉及利用²⁵²Cf源进行辐射效应试验研究的方法。结合功率MOSFET器件单粒子烧毁测试技术，对功率MOSFET器件辐射效应进行模拟试验研究。研究结果表明：在空间辐射环境下，功率MOSFET器件尽量使用在低电压范围内；在电路设计中附加必要的限流电阻是1种十分有效的抗单粒子烧毁措施。     

静态随机存取存储器辐射效应测试系统的研制

由于空间辐射效应会导致SRAM器件单粒子翻转、单粒子锁定等现象的产生。文中介绍了SRAM辐射效应测试装置的硬件、软件构成及有关测试技术。通过对SRAM芯片电流的检测、断电保护,解决了在SRAM实验过程中SRAM芯片的损坏问题,利用该装置在不同的辐射实验源上对SRAM进行辐射效应实验研究,获得了预期的实验数据。为星载计算机系统存储器的运行寿命评估及加固设计提供重要参考依据。     

MOSTET器件单粒子烧毁效应（SEB）截面测量

MOSFET功率管器件是卫星关键器件之一。单粒子烧毁(SEB)效应指由于功率晶体管中的高电流状态致使器件损伤,造成永久性破坏。在本MOSFET功率管烧毁效应截面测量实验装置的探测器室中,DUT为被研究的10片MOSFET功率管器件,连同检测探测器SD2和位置灵敏探测器PPSD一起,固定在可沿焦面移动的小车上。通过92芯真空密封座引出,器件与专用MOSFET功率管测试系     

同步辐射软X射线对单细胞的辐射损伤

应用国家同步辐射实验室软X射线显微术光束线的光学系统,搭建了适合软X射线单细胞辐照损伤效应研究的实验装置,选择氧元素K吸收边能量对Hela细胞进行单细胞辐照,运用单细胞凝胶电泳技术进行辐照损伤评价.实验结果表明,辐射损伤效应与辐射剂量有依赖性关系.     

JFET区宽度对SiC MOSFET单粒子效应的影响

SiC MOSFET(金属-氧化物半导体场效应晶体管)关键参数——结型场效应晶体管(JFET)区宽度一直被认为是SiC MOSFET单粒子效应的主要影响因素。针对这一影响因素,以同一结构不同JFET区宽度的1.2 kV SiC MOSFET器件为对象进行单粒子效应实验,探究JFET区宽度对器件单粒子烧毁阈值电压、漏电退化阈值电压以及负栅压条件下器件性能的影响。结果表明：随着JFET区宽度的减小,漏电退化阈值电压增大;减小器件JFET区宽度可有效改善器件的抗单粒子效应能力;在负栅压条件下对器件单粒子效应也会有此效果。采用Sentaurus TCAD进行模拟仿真,模拟结果证实,JFET区宽度以及负栅压的变化会影响氧化层下JFET区内空穴的积累,随之影响氧化层电场强度,从而影响器件单粒子漏电退化,与实验结果相符。以上结果为SiC MOSFET抗单粒子效应加固提供了理论基础。     

剂量率对MOS器件总剂量辐射性能的影响

对3种MOS器件在不同模拟源的两种辐照剂量率下进行辐照实验,研究了MOSFET阈值电压随辐射剂量及剂量率的变化关系。对实验结果进行了分析讨论。试验表明：在相同辐射剂量下,低剂量率辐照损伤比高剂量率大。     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

The preclinical pharmacological study of dopamine transporter imaging agent 18F-FP-β-CIT

The paper is to study pharmacologic characteristics of 18F-FP-β-CIT (18F-N-(3-fluoropropyl)-2β- carbomethoxy-3β- (4-iodophenyl)nortropane) as an imaging agent for dopamine transporter. The radiochemical purity of 18F-FP-β-CIT in aqueous solution was over 95% after standing at room temperature for 4h. Biodistribution displayed rapid uptake in rat brain (1.375 %ID/organ at 5min and 0.100 %ID/organ at 180 min) and the striatal uptake was 1.444,0.731, 0.397, 0.230 and 0.146 %ID/g at 5, 30, 60, 120 and 180 min, respectively. The values of striatum/cerebellum,striatum/frontal cortex and striatum / hippocampus in rat's brain at 30 min were 3.38, 2.17 and 2.40 respectively. The uptake in striatum can be blocked by β-CFT, suggesting that 18F-FP-β-CIT binds to DAT peculiarly. The compound was rapidly cleared from monkey's blood. The striatal uptake was bilaterally decreased in the left-sided lesioned PD rats, compared with normal control. Brain PET imaging studies in normal monkey showed that 18F-FP-β-CIT was concentrated in striatum. The test of undue toxicity showed that the dose received by mice was 1250 times as by human, which indicates that 18F-FP-β-CIT is very safe. So 18F-FP-β-CIT is a promising PET imaging agent for DAT with safety and validity.