高能重离子辐照制备SiOC复合材料的研究

用120 kev碳离子注入非晶SiO2薄膜,再用高能Xe、Pb和U离子辐照.注碳剂量范围为2.0×1017-8.6×1017 cm-2,高能离子辐照剂量1.0×1010-3.8×1012 cm-2.辐照后的样品用傅里叶变换红外光谱仪进行系统分析.实验结果显示,高能离子辐照在注碳非晶SiO2薄膜中形成了大量的Si-O-C键和Si-C键.这些Si-O-C结构具有环链、开链和笼链等多种结构形式.随电子能损、辐照剂量或者沉积能量密度的增加,SiOC结构由类笼向环/开链结构演化.对高能重离子驱动产生SiOC结构的机理进行了简单的讨论.     

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...     

高能铁离子辐照二氧化硅玻璃产生的缺陷研究

室温下用紫外-可见吸收光谱、荧光光谱和电子顺磁共振技术测量分析1.157 GeV56Fe离子辐照的二氧化硅玻璃,研究了高能重离子辐照产生缺陷的规律.紫外-可见吸收光谱测量结果显示,高能铁离子辐照产生了包括E'心、非桥连氧空穴心(NBOHC)和缺氧心ODC(Ⅱ)在内的多种缺陷结构.随着离子辐照量的增加,各类缺陷的数量逐渐增大并在高辐照量时趋于饱和.用单离子饱和损伤模型对实验结果进行拟合,获得了各类缺陷的产生截面在90-140 nm2.根据缺陷相对数量的变化关系探讨了E心和NBOHC的产生机制.荧光光谱显示,当以5 eV的紫外光激发辐照样品时,观测到三个荧光发射峰,分别位于4.28 eV(α带)、3.2 eV(β带)和2.67 eV(γ带),α带和γ带的存在证实辐照产生了ODC(Ⅱ)缺陷.实验发现β带是二氧化硅玻璃中的一种固有缺陷,高能离子辐照可使其部分脱色.电子顺磁共振测量进一步证实了E'心的产生规律.     

团簇沉积C-N薄膜的研究

利用荷能团族沉积装置在高阻硅（111）衬底上沉积了碳氮薄膜。通过红外光谱、拉曼谱和X光电子能谱对薄膜的结构和化学组分进行了分析。结果表明,薄膜中存在N－sp^3(β－C3N4的键合方式）,但以N－^2C和C＝C双键的结合方式为主。     

碳离子辐射对空间GaAs/Ge太阳电池性能影响的研究

利用2×1.7 MV串列静电加速器提供的碳(C)离子束模拟空间环境辐射,对空间GaAs/Ge太阳电池用注量为3.1×109-6.9×1012 cm-2的2 MeV C离子进行辐照.通过Ⅰ-Ⅴ特性和光谱响应测试,研究分析了GaAs/Ge太阳电池的C离子辐射效应.结果表明:随着C离子辐照注量的增加,GaAs/Ge太阳电池电性能参数Isc、Voc和Pmax衰降增大,其中Pmax衰降最大,Isc次之,Voc最小.该衰降规律和质子辐照的衰降规律相似.但使GaAs/Ge太阳电池的Pmax衰降到原值的50%,用C离子辐照所需注量要比相同射程的质子辐照小两个量级.在低注量辐照时,光谱响应衰降主要发生在长波范围;而注量大于3.1×1010 cm-2时,则发生明显的长、短波整个波段的光谱响应衰降;当注量增大到2.3×1011 cm-2以上,光谱响应基本消失.     

DLC薄膜中子辐照效应

采用射频等离子体化学汽相沉积法得到了类金刚石（以下简称DLC）薄膜,并用能量为14MeV的中子对其进行辐照,辐照剂量为1.4×1012n/cm2～7.2×1012n/cm2。通过Raman及红外光谱分析得出,中子辐照造成膜中SP3C-C键的明显减少及SP2C=C键的增加,并形成少见的非晶型SP1C≡C键碳（直线型碳）,使DLC膜进一步非晶化。经辐照后的DLC薄膜红外透过率均有所提高,在实验剂量范围内,基本上与辐照剂量无关。     

HFETR辐照石墨材料中子注量验证试验

钍基熔盐堆石墨材料辐照考验目标为:中子注量为5×10~(20)cm~(-2)(±15%)(E>0.1 Me V),堆内辐照试验温度650℃(允许偏差±50℃)。为了满足辐照考验要求,在高通量工程试验反应堆(HFETR)第92-I炉的K07孔道进行辐照验证试验。该验证试验辐照装置采用分段构成的型式,主要由辅助密封段、辐照试验段、气管组件3部分构成,辐照罐外围为去离子水,辐照罐内为惰性气体用于控制辐照试验温度。使用MCNP程序对各样品中子注量进行预示计算,同时在辐照装置阳面和阴面都布置了探测器进行中子注量测量。试验表明:在辐照试验过程中,在辐照装置调气系统最佳导热模式下辐照温度略高于上限700℃;利用MCNP程序预示计算中子注量结果为5.7×10~(20)cm~(-2)(E>0.1 Me V),而中子注量测量结果为4.83×10~(20)cm~(-2)(E>0.1 Me V),基本满足石墨材料辐照考验中子注量要求。     

基于多模式扫描探针显微镜技术分析碳化硅的辐照损伤

本文在600℃对6H-SiC进行了He~+辐照实验,离子辐照能量为100 keV,剂量为5×10~(15)ions·cm~(-2)、1×10~(16)ions.cm~(-2)、3×10~(16)ions.cm~(-2)和8×10~(16)ions·cm~(-2)。本文采用多模式扫描探针显微镜技术,包括轻敲模式原子力显微镜、纳米压痕/划痕和导电模式原子力显微镜技术对样品辐照前后的表面损伤进行了分析。结果表明,随辐照剂量的增加,样品表面粗糙度逐渐增加,表面硬度逐渐下降。导电模式原子力显微镜能清晰地观测到样品表面氮泡分布形态,进一步说明材料表面的肿胀是由材料内部高压氮泡产生的。     

类金刚石薄膜的同步辐射光电子能谱研究

利用同步辐射光电子能谱全电子产额模式(TEY)对石墨、金刚石薄膜和类金刚石薄膜(DLC)的ClsX射线吸收谱进行了研究。在高真空里表面净化处理后,在类金刚石薄膜的Cls吸收谱中分别观察到对应于金刚石sp^3杂化结构成分和石墨sp^2杂化结构成分的特征峰,说明了类金刚石薄膜是由碳sp^2、sp^3两种杂化结构无序混合形成的非晶碳结构;然后,测量了一系列类金刚石薄膜样品的ClsX射线光电子能谱(XPS),得到了每组样品的sp^2、sp^3成分比。     

熔盐/辐照环境中细结构等静压石墨的结构和化学稳定性研究

熔盐堆以石墨作为反射体和慢化体,熔盐与石墨直接接触,石墨在熔盐中的腐蚀反应和辐照损伤是值得研究的问题。本文采用自主研发的细结构石墨,阻隔熔盐浸渗,采用30 MeV He+模拟中子辐照,研究不同温度及熔盐环境下石墨微观形貌、微结构和化学结构的变化。研究结果表明,高温环境下,由于高温的退火效应,石墨缺陷密度的增加及形貌的变化都远小于室温环境。辐照后的石墨与熔盐接触,其缺陷密度略微降低。这种微结构的改善与高温熔盐环境中的退火效应及熔盐固化引起内部微裂纹的闭合有关。辐照后的熔盐浸泡可在石墨C—C键结构中引入C—F键,且C—F键的形成与缺陷密度及缺陷类型密切相关。稳定的空位簇及间隙原子的迁移均会影响层间化合物的形成,从而产生限制C—F键形成的环境,进而降低由层间化合物的形成对石墨表面结构的破坏。     

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.     

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。     

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.     

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.     

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.     

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.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.     

微型X射线管空气比释动能和能谱的测量

为研究微型X射线管的特性,通过电离室测量光管出射口30 cm远处的空气比释动能,使用高纯锗探测器分别测量了Ag过滤和Cu过滤下的X射线能谱。结果表明,空气比释动能随电流的增加有线性增加的趋势,能谱图明显的观察到银的两个特征X射线。完成了微型X射线管空气比释动能和能谱的测量方法以及实验测量的工作,为微型x射线管下辐射质的建立提够了条件基础。     

Gamma-ray attenuation technique for measuring void fraction in horizontal gas-liquid two-phase flow

The measurement of void fraction is of importance to the oil industry and chemical industry. In this article, the principle and mathematical method of determining the void fraction of horizontal gas-liquid flow by using a single-energy γ-ray system is described. The γ-ray source is the radioactive isotope of 241Am with γ-ray energy of 59.5 keV. The time-averaged value of the void fraction in a 50.0-mm i.d. transparent horizontal pipeline is measured under various combinations of the liquid flow and gas flow. It is found that increasing the gas flow rate at a fixed liquid flow rate would increase the void fraction. Test data are compared with the predictions of the correlations and a good agreement is found. The result shows that the designed γ-ray system can be used for measuring the void fraction in a horizontal gas-liquid two-phase flow with high accuracy.