热中子非弹性散射及其在材料科学中的应用

本文扼要地叙述了热中子与凝聚态物质相互作用的基本散射理论,说明了热中子非弹性散射实验方法的特点。此外,还介绍了在一定条件下的声子色散关系、声子态密度和自扩散系数的表达式。最后,列举了国内、外有关声子色散关系曲线、声子态密度和自扩散系数实验测量的几个实例。     

热中子非弹性散射及其在材料科学中的应用

本文扼要地叙述了热中子与凝聚态物质相互作用的基本散射理论,说明了热中子非弹性散射实验方法的特点。此外,还介绍了在一定条件下的声子色散关系、声子态密度和自扩散系数的表达式。最后,列举了国内、外有关声子色散关系曲线、声子态密度和自扩散系数实验测量的几个实例。     

西安脉冲堆超热中子束的理论设计

建立超热中子束孔道筛选的三维扩散型,并用蒙特卡罗程序MCNP／4B验证了热柱孔道是实现超热中子束的佳孔道,还建立了硼中子俘获治疗（BNCT）所需超热中子束的理论设计方法,对超热中子束过滤材料的特性进行了分析,提出了将西安脉冲堆热柱孔道改造成超热中子束孔道的3种材料组合方案。     

高灵敏中子剂量当量率仪宽能区响应函数曲线的校准

参考国家相关标准和国际标准化组织(ISO)及国际电工委员会(IEC)对中子剂量当量(率)仪校准的相应标准,对已设计加工组装完毕的一台长圆柱型、较大体积高灵敏中子剂量当量率仪在宽能区(热中子～20MeV)内进行了能量响应和剂量灵敏度的实验校准。能谱响应函数曲线实验校准采用参考仪器和监测仪器归一校准法,利用实验和理论计算方法确定了NH-1型中子剂量当量率仪在较宽能区(热中子～20MeV)内的能量响应曲线;并给出了仪器的综合灵敏度48.9cps/(μSv.h-1)以及在3种特征能谱中的剂量响应。     

PNN测井热中子时间谱的多尺度滤波研究

PNN(脉冲中子-中子)测井是利用He-3管记录热中子时间谱,进而求取地层宏观俘获截面的一种测井方法。热中子时间谱滤波处理是获取有效地层宏观俘获截面值的研究基础。针对热中子时间谱的特点,以X井为研究对象,在探讨小波基及阈值的量化处理基础上,采用了基于阈值收缩的多尺度滤波方法,分别在纵向和横向对热中子时间谱进行了多尺度滤波处理。滤波结果显示热中子计数随时间呈指数规律衰减,满足时间谱后处理的需要。这些探索为PNN测井时间谱的滤波处理提供了一种新方法。     

热中子研究堆薄板型控制棒价值计算

对通过采用能量相关的内边界条件，在扩散理论的范围内计算薄板型热中子研究堆控制棒价值进行了理论分析，成功地计算了日本原子能研究所JRR-3M的控制棒价值，并与日本的计算结果进行了对比。     

HFETR堆芯热中子阱研究

采用扩散和输运两种方法对高通量工程试验堆（HFETR）热中子阱进行研究。计算结果表明：水热中予阱的最佳热阱半径为6．0cm，其最大热中子注量率约是无阱时最大热中子注量率的3．1～3．7倍；铍一水热中子阱的最佳热阱半径分别为7．5cm（扩散方法）和2．5cm（输运方法），其最大热中子注量率约是无阱时最大热中子注量率的3．2～4倍．     

铑自给能中子探测器的灵敏度

本文给出了铑自给能探测器的热中子灵敏度和中子灵敏度的理论计算公式、燃耗修正公式以及不同中子温度下的换算公式。运用这些公式对ZTRh 123型铑自给能探测器的热中子灵敏度和中子灵敏度进行了理论计算,并在反应堆中对其进行了实验验证。其结果表明,理论计算值和实验标定值是相吻合的。其偏差:热中子灵敏度为8.5％,中子灵敏度为3.9％。     

用于热中子探测的正比管性能研究

简要对最常用的三种正比管的热中子探测效率及灵敏度进行了实验比较，还给出了一维^3He位置灵敏热中子探测器的初步实验研究结果。     

基于重复结构卡的BNCT人体头部精细模型剂量分布计算

针对目前BNCT治疗脑胶质瘤所采用的头部模型的粗略性,用MCNP程序的Universe和Fill重复结构卡对人体头部的精细模型进行描述,分别使用热中子、超热中子和快中子对大脑在有、无载硼剂时的剂量分布进行了计算,得到了剂量率随深度分布的曲线.计算结果与有关文献的报道结果相吻合,本文所构建的人体头部精细模型是正确的.     

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.     

有效探测面积大于1000 cm2的正比计数器测量系统性能测试

为对自制的活性面积高达1 000 cm²的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的²⁴¹Am点源及活性区面积为10 cm×15 cm的大面积²⁴¹Am和⁹⁰Sr-⁹⁰Y源对其进行计量学性能测试。结果表明：计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm²;所得²⁴¹Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;⁹⁰Sr-⁹⁰Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。     

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.     

Interaction between uranium and humic acid (Ⅰ): Adsorption behaviors of U(Ⅵ) in soil humic acids

The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) ＞SHA (HA from the surface) ＞THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g)ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5 - 6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.     

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。     

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.     

Information for authors

<正>1.NUCLEAR SCIENCE AND TECHNIQUES(NST),a bimonthly journal,is devoted to all aspects of nuclear science and technology,theoretical or experimental.Its special interest lies in the subjects of synchrotron radiation science and technology;low energy accelerators,radiation technology and applications;radiochemistry,radiopharmaceuticals and nuclear medicine;nuclear electronics and instrumen-     

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

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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.