1.5 MeV He~+离子注入SI-GaAs制备太赫兹光电导天线

用1.5MeV He+离子注入半绝缘砷化镓晶体(SI-GaAs),以其为基体制成光电导天线。太赫兹时域光谱测量显示,以离子注入晶体为基体的光电导天线,其时域信号强度是未注入晶体的3倍,略强于以LT-GaAs晶体为基体的光电导天线,但拥有比LT-GaAs晶体为基体的光电导天线略宽的频谱宽度和相当的信噪比。实验结果表明,用1.5MeV He+室温注入SI-GaAs制备太赫兹光电导天线的最佳注量约为1×1016ions·cm-2。     

离子辐照缺陷对太赫兹波发射性能的影响

应用半经典的蒙特卡罗方法,模拟计算了处于不同缺陷条件下的砷化镓在超快激光激发下的载流子输运行为及其相应的太赫兹波发射性能。计算结果表明,缺陷的类型和浓度都会对太赫兹波的脉宽和峰高产生显著的影响。分别采用500 keV和1.5 MeV的氮离子在不同剂量下辐照了半绝缘的砷化镓和掺铁磷化铟样品,并将辐照样品制备成太赫兹波发射天线。通过对辐照样品的太赫兹波发射能力进行测量,发现不同辐照条件下制备的太赫兹发射天线其太赫兹波的脉宽基本一致,只有峰高随辐照产生的缺陷浓度增大呈现先增大后减小的变化。结合理论计算和实验测量结果,分析讨论了光电导材料太赫兹波发射的缺陷机制。     

基于WG-PM与HEMT的高定向光学发射器设计

为了使无线通信系统短距离数据传输速率达到10 Gbit/s,利用光电结合技术以THz波段为载波,建立了太赫兹无线通信系统.为提高无线通信系统的传输距离,设计了带有高增益天线和波导输出光电二极管模块的光学发射器.模块采用载波单向导通光电二极管、宽带高电子迁移率晶体管放大器和平面电路-波导转换衬底等技术.并对适合分析太赫兹...     

1.55 MeV 3He离子辐照单晶Si引起的损伤效应研究

室温下使用1.55 MeV、5×1013-5×1016/cm2注量的3He离子注入单晶Si,采用透射电子显微镜(TEM)观测分析了高温退火后单晶Si中由注入引起的损伤形貌,同时使用核反应分析(NRA)技术研究了3He气体原子的热解吸.结果显示,低注量3He离子注入在Si中产生的缺陷主要为一些小尺寸的位错或位错环;在中等照射剂量,退火导致了气泡和气泡团簇的形成并伴随着高密度的位错环从这些气泡团簇中发射出来;而对于较高的照射剂量,3He离子注入加上随后的高温退火则在离子射程附近产生了一个具有确定边界的空腔带.结合NRA结果对实验现象进行了分析.     

O、C离子注入n型GaN的黄光发射研究

采用光致发光(Photoluminescencc,PL)谱的测量,研究了1012～1017cm-2的O和C两种离子注入和退火对非有意掺杂的n型GaN黄光发射(Yellow luminescence,YL)的影响,注入后的样品在流动N2的保护下进行退火,退火温度950℃,退火时间30 min.对比相同剂量下N离子注入GaN黄光发射,结果表明O、C两种离子的注入在GaN中分别引入了与黄光发射相关的不同的深能级中心,当C离子注入剂量高达1017cm-2时,能引起黄光发射的C相关的深能级中心显著增多.     

H、He离子辐照对国产ZIRLO合金氧化膜的影响

针对国产ZIRLO合金开展了H、He离子辐照对其腐蚀性能影响的研究。对国产ZIRLO合金样品分别进行高温（300 ℃）H、He离子辐照试验，辐照峰值剂量为1 dpa，之后进行模拟一回路腐蚀试验。通过腐蚀增重方法得到腐蚀动力学曲线。利用慢正电子湮没多普勒展宽谱对未辐照样品和辐照样品进行微观结构表征，用透射电子显微镜对腐蚀125 d的样品进行微观结构表征。结果表明，H、He离子辐照并未改变ZIRLO合金的腐蚀机理。He离子辐照产生的空位团可促进腐蚀过程中裂纹形核，增加了氧扩散通道，减少氧扩散激活能，导致腐蚀初期有明显的加速效应。H离子辐照对腐蚀的加速现象不如He离子辐照明显，原因是H离子辐照产生H-空位复合缺陷对氧扩散激活能减少作用较小。     

利用淀粉粘滞性谱快速检测稻米辐照研究

为了快速鉴别或检测稻米是否经过辐照杀虫处理,研究了粳米经辐照处理后淀粉粘滞性谱的变化规律.结果表明,随吸收剂量增大淀粉粘滞性显著下降,在检测助剂的调控下,辐照与未辐照的淀粉粘滞性谱有明显差异.利用淀粉的最高粘度、热浆粘度、冷胶粘度与吸收剂量之间的变化关系,可估算稻米辐照后的吸收剂量.借助检测助剂的调控,可快速检测稻米是否经过辐照处理.     

Pb离子辐照注碳a-SiO2薄膜的光致发光性能

用湿氧化法在单晶硅表面生长了非晶态SiO2薄膜,进行120 keV C离子注入和950 MeV Pb离子辐照,用荧光光谱分析样品发光特性的改变.结果发现,C离子注入和高能Pb离子辐照均能显著影响样品的发光特性,且荧光光谱的改变强烈依赖于注入和辐照剂量,预示不同注入和辐照剂量将导致不同的发光结构形成.对注入和辐照造成薄膜...     

钛离子注入9Cr18钢的强流脉冲电子束后处理

对９Ｃｒ１８钢经Ｔｉ＾＋离子注入后又使用脉冲强流电子束进行了表面辐照处理用ＡＥＳ分析了注入层的成分,考查了电子束处理前后的硬度,并讨论了脉冲强流电子对离子注入金属材料表面成分产生辐照增强扩散的影响。     

色心激光器材料LiF和LiF：（OH）^—的正电子湮没谱研究

对LiF(F_2~+)和LiF:(OH)~-(F_2~+)色心晶体经液氮温度电子束辐照后,在室温下放置不同时刻的正电子湮没谱进行了研究,发现寿命谱中第一、第二成分的相对强度I_1、I_2及Doppler展宽谱中S参数随着F_2~+心的衰减呈有规律的变化,且与辐照剂量有一定关系。     

Shallow-Land Buriable PCA-Type Austenitic Stainless Steel for Fusion Application

Neutron-induced activity in the PCA austenitic stainless steel is examined, when used for first-wall components in a DEMO fusion reactor. Some low-activity definitions, based on different waste management and disposal concepts, are introduced.

Activity in the PCA is so high that any recycling of the irradiated material can be excluded. Disposal of PCA radioactive wastes in Shallow-Land Buriable (SLB) is prevented as well. Mo, Nb and some impurity elements have to be removed or limited, in order to reduce the radioactivity of the PCA. Possible low-activity versions of the PCA are introduced (PCA-la); they meet the requirements for SLB and may also be recycled under certain conditions.     

高温He离子辐照GH3535合金的损伤效应

采用500 keV的He离子在750 ℃下对GH3535合金样品进行辐照，然后利用掠入射X射线衍射（GIXRD）、透射电子显微镜（TEM）和纳米压痕仪分别对样品的氦泡和位错环辐照缺陷的演化及纳米硬度的变化进行了研究。结果表明，GH3535合金晶格辐照后发生了轻微畸变；离子辐照在样品中形成了大量尺寸为2～5 nm的氦泡和位错环。辐照产生的氦泡和位错环等缺陷在基体中钉扎位错，从而使材料产生了辐照硬化现象，样品硬度随辐照剂量的增加而增大。当辐照剂量达2×1016 cm-2时，辐照样品发生了明显的硬化饱和现象，利用Nix Gao模型计算得此时的硬化程度为64%。     

聚二甲基硅氧烷在过氧化氢溶液中的伽玛辐射效应

研究了6%过氧化氢(H_2O_2)溶液中的聚二甲基硅氧烷(Polydimethylsiloxane,PDMS)橡胶材料的g辐射效应。首先利用拉伸实验测试了辐照前后PDMS橡胶材料力学性能的变化,然后利用甲苯平衡溶胀法,差示扫描量热分析和傅里叶变换衰减全反射红外光谱分析(Attenuated total reflection-Fourier transform infrared,ATR-FTIR)法对其辐照前后的化学结构变化进行了表征。结果表明,在H_2O_2溶液中辐照的PDMS仍发生以辐射交联为主的反应,且在相同的吸收剂量下,相较于空气中辐照的PDMS,在H_2O_2溶液中辐照的PDMS的断裂伸长率较高,弹性模量较小,交联密度较低。这可能是由于H_2O_2溶液在辐照过程中产生的氧化性活性物质能够捕获PDMS辐照生成的大分子活性自由基,从而降低了PDMS发生交联反应的概率。ATR-FTIR结果则进一步表明,随着吸收剂量的增加,PDMS表面出现一定程度的氧化,而相较于空气中辐照的样品,在H_2O_2溶液中辐照的样品表面氧化程度并未明显增强。     

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.     

Provenance studies of archaeological ceramics from Mar-Takla(Ain-Minin,Syria)using radioisotope X-ray fluorescence method

The radioisotope X-ray fluorescence method was applied to studies of the provenance of the ceramics fragments originated from the Mar-Takla site in Syria.The samples were irradiated 1000s by a ^109Cd radioisotope source and 13 elements (Ca,Ti,Mn,Fe,Zn,Ga,As,Rb,Sr,Y,Zr,Nb,and Pb)were determined in 35 samples.The data were subjected to two multivariate statistical methods,cluster and principal components analysis(PCA).It was shown from the combination of the statistical techniques and the determination of elemental composition of the samples that 94% of the ceramic samples analyzed can be considered to be manufactured using two sources of raw materials.     

Investigation of irradiated uranium-plutonium mixed oxide fuel by synchrotron based micro X-ray diffraction

Specimens of a 4.7 wt % plutonium MOX fuel, irradiated for a period of 6 years up to 60 MW d kg⁻¹ were investigated using synchrotron based micro X-ray diffraction technique (μXRD). The μXRD measurements at the Swiss Light Source SLS with a beam spot size of about 2 μm × 2 μm were carried out on the center and periphery region on the cross section of the irradiated fuel, as well as on un-irradiated reference MOX material. The profiles of characteristic (111), (200), (220), (311) and (222) diffraction lines of the irradiated samples were analyzed in detail and compared with the data of the non-irradiated MOX material, revealing the lattice distortion and dilatation in the irradiated fuel matrix. Broadening of reflexes can be observed due to the increasing stress finally yielding strain up to fuel grain fracture. This phenomenon is quantified thanks to the analysis of the reflexes arcs fine structure. The sub-grain number per grain volume is analysed as a function of fuel location and history.     

γ辐照30%三烷基氧化膦-煤油体系萃取乳化的研究

研究了γ辐射三烷基氧化膦（TRPO）的乳化性能，实验表明，萃取水相酸度的增加，有利于去乳化作用。γ辐射对305TRPO－煤油－硝酸体系的乳化作用有显著影响，不同厂家生产的TRPO具有不同的乳化性能。γ辐照的磷酸三丁酯(TBR)－煤油－硝酸体系较TRPO－煤油－HNO3体系分相和去乳化速度较快。但当用5％Na2CO3溶液洗涤上述两个体系时，TBP－煤油体系有机相去乳化速度较慢，其平衡水相有乳化现象，而TRPO－煤油体系虽分相慢，但分相后有机相的去乳化速度较快，其平衡水相无乳化现象。     

含脂食品辐解产物2–烷基环丁酮的研究进展

含脂食品被辐照时,食品中的脂肪酸和酰基甘油会分解形成相应的同碳原子数2–烷基环丁酮(2-alkylcyclobutanones,2-ACBs)。自发现以来,2-ACBs一直是含脂辐照食品研究的热点。作为含脂食品辐照的标志性化合物,2-ACBs可用来检测含脂辐照食品。2-ACBs的产生及其稳定性受很多因素影响,如辐照剂量、辐照温度与贮藏条件等。同时,2-ACBs的毒理性也一直是含脂辐照食品研究的热点。本文阐述了利用2-ACBs检测含脂辐照食品方法的研究现状;影响2-ACBs的产生和稳定性的因素;以及2-ACBs的毒理性研究进展。     

Color center creation in LiF crystals irradiated with Xe, Kr and N ions: Dependence on fluence and beam current density

Single LiF crystals were irradiated with Xe (195 MeV), Kr (117 MeV), and N (18 MeV) ions. Using absorption spectroscopy, color center creation was analyzed as a function of the ion energy loss, fluence, and flux. The concentration of single F centers and F₂ centers versus fluence and flux exhibits a nonlinear evolution with saturation at higher fluences. For LiF irradiated with N ions at high fluence, the concentration of F centers is proportional to the cube root of the flux indicating the strong interaction of primary hole centers. Macroscopic hillocks were observed in all irradiated LiF crystals by atomic force microscopy.     

Wear and corrosion resistance of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

The wear and corrosion resistance of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam (HIPIB) at an ion current density of 100–300 A/cm² with shot number of 1–10 are investigated by sliding wear test and potentiodynamic polarization measurement. The surface and cross-sectional morphologies, phase structure and surface microhardness of the irradiated AZ31 magnesium alloy samples are characterized by scanning electron microscopy (SEM), optical microscopy, X-ray diffraction (XRD) and Vickers tester, respectively. The HIPIB irradiation produces the hardened surface layers and improves abrasive wear resistance of all the samples. The wear volume of the irradiated samples at 200 A/cm² and 300 A/cm² with 10 shots as well as 100 A/cm² with 5 shots is about four times less than that of the original sample. The apparent increase in corrosion resistance is achieved for all the irradiated samples in 0.01 mol/l NaCl solution with a pH value of 12. The corrosion potential and pitting breakdown potential for the samples irradiated at 100 A/cm² with 5 shots are 560 and 630 mV higher than those of the original sample, −1560 mV and −1300 mV (SCE), respectively. It is found that the combined improvement in wear and corrosion resistance of AZ31 magnesium alloy is achieved by HIPIB irradiation, which is ascribed to the microstructural refinement and the chemical homogeneity of the irradiated magnesium alloy.