离心沉淀法制备粉末材料靶

一、引言核物理实验一般希望使用的自支撑靶,主要用真空蒸发、电镀和滚轧等技术来制备。但制备希土和硷土金属,高熔点材料以及数量较少而又贵重的同位素材料的自支撑靶就比较困难。一般说来,这些元素的同位素以氧化物,碳酸盐等化合物粉末状存在。对这些粉末材料可配制成溶液或悬浮液,用重力沉淀,电喷涂,电泳等方法来制备有衬底靶。这些     

几种特殊的滚轧制靶技术

描述了几种特殊的滚轧技术，包括中间退火，双层的材料靶的轧制电容器纸作内衬，气体靶室封窗膜的制备，材料熔化和粉末材料靶的轧制等。     

多孔氧化铝的制备及表征

采用两类不同制备方法,分别制备出多孔氧化铝薄膜和多孔粉末氧化铅。薄膜多孔氧化铝的制备是通过二次阳极氧化法来实现。经不同电压下的一次阳极氧化、二次阳极氧化以及相同电压下的时间单因素实验可知,制备薄膜氧化铝的最佳工艺条件为：二次阳极氧化时间,7h;氧化电压,40V。分别使用加热法、水热法、溶胶 凝胶法制备粉末多孔氧化铝,利用XRD、热分析、N₂吸附脱附和TEM对粉末多孔氧化铝进行表征。溶胶 凝胶法制备的粉末氧化铝比表面积最大,达到263m²/g,且具有较宽的孔径分布、较大的孔容。     

用分子镀法制备钕靶

众所周知,没有一种薄膜制备的方法能对各种材料普遍适用。目前,少数稀土元素可用真空蒸发的方法制备核物理实验用靶,但收集效率较低,同时由于稀土金属蒸发温度高,使靶造成污染。而分子镀方法是适于稀土元素快速定量的一种电沉积方法。它和一般电沉积方法的区别在于:电流通过期间以化合物的形式沉积在阴极上,保持恒定的高电压,使用有机溶剂。这种方法制备靶的优点是能给出极薄的薄膜或较厚的膜(10～2000μg/cm~2以上);大多数情况下沉积的膜是比较均匀的,并有很好的附着力,沉积效率可达100％,沉积时间短,制备样品所需的材料量少并易处理,所以对稀有或贵重材料如放射性同位素制靶是特别适用的。本文叙述了在异丙醇溶液中电沉积制备Nd靶的方法。     

低密度氢(氘)化锂微靶制备工艺

研究采用氢(氘)化锂粉末松装填充微靶柱腔,在氩气保护气氛中以10 ℃/h速度升温至430 ℃并保温,烧结30 min,制备直径0.6～1.0 mm、长1～2 mm的氢(氘)化锂微靶.不添加造孔剂的氢化锂和氘化锂微靶密度分别可达(0.283±0.009) g/cm3和(0.369±0.009) g/cm3.以氘化锂与造孔剂C型环二体混合粉末松装柱腔烧结制备的微靶试样密度达到(0.301±0.010) g/cm3.该造孔剂对氘化锂粉末烧结材料的物理品位、氘丰度、6Li丰度无明显影响.严格的氩气保护气氛是防止氢(氘)化锂微靶物理品位降低的有效手段.     

氟体系AUC流程制备陶瓷UO_2粉末及其母液处理工艺

介绍了以UF6水解液为原料采用气提环流搅拌沉淀反应器制备AUC粉末、用流化床分解还原氟体系AUC制备陶瓷级UO2粉末、用离子交换树脂处理含氟废液中的铀和用生石灰沉淀离子交换尾液中氟的处理工艺。具体研究了以UF6水解液为原料制备AUC粉末的主要控制参数;讨论了氟体系制备的AUC粉末与硝酸体系制备的粉末的各种差异。实验结果表明:采用气体环流搅拌反应器并以UF6水解液为原料制备AUC粉末,组成恒定且质量稳定,重现性好;采用流化床技术分解还原氟体系AUC晶体,并在最佳工艺条件下能够稳定地获得性能优良的陶瓷级UO2粉末,完全满足Gd2O3-UO2芯块制造的要求。     

悬浮硼粉喷射法制备硼靶

一般制备同位素~(10)B靶,需要使用较大功率的电子枪;不然难以蒸发制备成靶,特别是厚靶。我们将硼粉制成悬浮状态,用小型玻璃喷雾器,将悬浮硼粉喷射到靶衬底上,制成了牢度较好、厚薄比较均匀的、直径为8～12mm、厚度为400～1500μg/cm~2的~(10)B靶,使用这种靶,成功地进行了实验工作,得到了比较满意的成果(见图1)。 硼的比重为1.73～2.34,一般呈无定形或结晶的粉末,放入液体会产生沉淀。因此,只有将粉末磨细,构成分布均匀的~(10)B悬浮液体,才能用悬浮喷雾法制靶。我们利用小型三轴球磨机进行滚磨,比较好地解决了硼粉的研磨问题(装置示意图见图2)。研磨瓶采用九五料硬质玻璃制成,尺寸见图3所示,内装φ15、φ10、φ5的玛瑙球各10个。这样能使硼粉得到充分的研磨。在研磨过程中,为了不使悬浮剂漏出来,必须用透明胶纸加以密封,并在密封罐外绕上二圈胶布防止在转动过程中打滑(见图4)。     

PSⅡ工业样机用平面磁控溅射靶设计及工艺实验

根据全方位等离子体源离子注入(PSII)工业样机实验和应用的需要,用等效电流磁场计算法获得的数据结果,设计了一种子面磁控溅射靶。并利用此平面磁控靶在一定的Ar、N_2气体分压及不同电流、电压条件下,成功地制备出金黄色氮化钛薄膜,并利用台阶轮廓仪测量了TiN薄膜的沉积速率,这表明该靶的沉积速率能满足增强沉积TiN涂层的需要。 在现代工业的许多领域中,已认识到提高材料的耐磨损、耐腐蚀的必要性和迫切性,而对材料表面进行改性是提高材料性能的最有效和经济的手段。离子注入技术作为金属材料表面性能改善的有效手段,愈来愈受到人们的关注。特别是近年来发展的全     

同位素208Pb靶的制备

介绍了一种弧形靶框夹芯208pb靶的制备工艺,包括核靶的制备装置和制备方法、核靶厚度和均匀性的控制和测量方法,并对结果进行了讨论.制备采用旋转蒸镀法,该法可以大大提高材料的利用率.所制靶的结构为30μg/cm2 C+361 μg/cm2 208pb+15 μg/cm2 C,同一次所制的靶平均厚度为361μg/cm2,不均匀性小于9.8%.其性能能够很好地满足超重核实验研究的要求.     

同位素208Pb靶的制备

介绍了一种弧形靶框夹芯^208pb靶的制备工艺,包括核靶的制备装置和制备方法、核靶厚度和均匀性的控制和测量方法,并对结果进行了讨论.制备采用旋转蒸镀法,该法可以大大提高材料的利用率.所制靶的结构为30μg/cm^2 C＋361 μg/cm^2 ^208pb＋15 μg/cm^2 C,同一次所制的靶平均厚度为361μg/cm^2,不均匀性小于9.8%.其性能能够很好地满足超重核实验研究的要求.     

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.     

Characteristics of pulsed photo-stimulated luminescence and thermoluminescence for the identification of gamma irradiated poultry eggs

Pulsed photo-stimulated luminescence (PPSL) is a simple screening method that can be employed qualitatively at the spot for the detection of eggs treated with ionizing radiation.Due to the variations in the results during storage,the eggs of ostrich,duck,hen,and quail were irradiated to doses of 0,1,2,and 3 kGy.Most of the samples were incorrectly identified during storage after four months of irradiation.Thermoluminescence (TL) technique was also tried by using egg shells in order to confirm the irradiation treatment in eggs.TL glow curves were recorded between the temperatures 50℃to 400℃at the rate of 5°/s for all the control and irradiated samples.On the basis of integrated areas of first glow curves (TL1),the glow curve ratios (TL1/TL2) and the shapes of maxima of TL1, the irradiation treatment of all the eggs was confirmed.Furthermore,the presence of calcite and aragonite minerals that cause the TL signal in the egg shells were studied using X-ray diffraction spectrometry.     

数字射线扫描成像系统MTF的测试分析

为有效实现数字射线扫描成像检测系统性能的定量分析评价,据此进行检测工艺参数的优化,对数字射线扫描成像检测系统调制传递函数(Modulation transfer function,MTF)进行了测试分析。采用刀口工具、双线型像质计、分辨率测试卡,对系统在不同焦点大小、放大倍数、运动方向的检测情况,分别进行了MTF的测试并进行了比较。结果表明,双线型像质计与分辨率测试卡的测试结果基本一致,但双线型像质计更便于对比度的定量计算;双线型像质计的对比度传递函数近似符合二次曲线,经转换得到的调制传递函数值高于刀口法的测试值,刀口法计算数值偏低的原因在于运动不平稳所带来的不利影响。分析表明,数字射线扫描成像系统性能受到多个因素的共同影响,MTF测试结果可较全面地对影响因素进行定量评价,可用于确定最佳的检测参数或找出等价的参数组合。     

基于物理体模CT图像的1岁儿童体素体模构建

本文介绍了基于1岁儿童物理体模（Model 704-D）的CT图像和中国成年男性参考人体素体模(CRAM)的1岁儿童体素体模（CPP01）的构建,包括通过对物理体模扫描得到OCP01体模（基于儿童物理体模的CT图像建立的一粗略的体素体模）,进而构建和优化CPP01。该体素体模的各器官组织的质量与GBZ/T 200.2-2007所给数据的相对偏差约在5%以内,且其外部轮廓和主要器官的位置与Model 704-D相匹配。     

Activity level of gross α and gross β in airborne aerosol samples around the Qinshan NPP

The monitoring results of gross α and gross β activity from 2001 to 2005 for environmental airborne aerosol samples around the Qinshan NPP base are presented in this paper. A total of 170 aerosol samples were collected from monitoring sites of Caichenmen village, Qinlian village, Xiajiawan village and Yangliucun village around the Qinshan NPP base. The measured specific activity of gross α and gross β are in the range of 0.02 ～ 0.38 mBq/m3 and 0.10 ～ 1.81 mBq/m3, respectively, with an average of 0.11 mBq/m3 and 0.45mBq/m3, respectively. They are lower than the average of 0.15 mBq/m3 and 0.52mBq/m3, of reference site at Hangzhou City. It is indicated that the specific activity of gross α and gross β for environmental aerosol samples around the Qinshan NPP base had not been increased in normal operating conditions of the NPP.     

Simulation of the mixing process in FCIs with hydrodynamic fragmentation model

Fuel Coolant Interactions (FCIs) are important issues in nuclear reactor severe accident analysis. In FCIs, fragmentation model of molten droplets is a key factor to estimate degree of possible damage. In this paper, the mixing process in FCIs is studied by the simulation of MIXA experiment with hydrodynamic fragmentation model. The result shows that hydrodynamic fragmentation model underestimates the fragmentation rate of high temperature molten droplets under the condition of low Weber numbers. It is concluded that models based on thermal fragmentation mechanism should be adopted to analyze the FCI process and its consequence.     

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.     

PLASMA SCIENCE AND TECHNOLOGY AUTHOR INDEX TO VOLUME 16(2014)

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NUCLEAR SCIENCE AND TECHNIQUES Volume 25,2014

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Probing stray surface electric patch fields using Rydberg atoms

The stray electric “patch” fields present at a Au(1 1 1) surface are investigated by studying the ionization of Rydberg atoms incident at near-grazing angles. Measurements of the threshold conditions required to observe the resulting ions are used to estimate how large such stray fields can be. The data show that the stray fields can be sizeable, as large as ∼10³ V cm⁻¹ 100 nm from the surface and ∼20 V cm⁻¹ 500 nm from the surface, and illustrate the potential of Rydberg atoms for detecting and characterizing surface electric fields.