BESⅢ飞行时间电子学在线刻度电路

本文介绍了BESⅢ(北京正负电子对掩机第三代谱仪)飞行时间(TOF)读出电子学在线刻度电路.该电路被集成在读出电子学插件上,用VME总线接口在线控制高精度DAC和高速模拟开关,产生幅度(电荷)可程控的指数衰减脉冲,对电子学通道进行时间测量检测和电荷测量的非线性校准,有大于20倍的电荷动态范围和好于10 bit的精度,能有效实现电荷非线性的校准功能.经测试,刻度修正后TOF电子学电荷测量的积分非线性小于0.69%,远好于修正前2%的性能指标,满足设计要求,目前该刻度电路已成功应用于BESⅢ工程.     

六端口自动反射计及其在盘荷波导调配中的应用

本文简述了六端口自动反射计的原理,介绍了我们研制的自动反射计和用它来调配北京正负电子对撞机的直线加速器盘荷波导的结果。实验表明,相位调谐精度远优于测量线法,误差很容易控制在±1.5°范围内,调配速度比用测量线法提高十倍以上。全部结果可由计算机存盘保存,并由打印机,绘图机输出。     

用于防护级照射量实验室标准的薄壁球形电离室

本文介绍了一种可作为防护级照射量实验室标准的塑料薄壁球形电离室的设计和主要性能。该电离室容积为100cm~3;本底电流不大于1×10~(15)A;在33keV—1.25MeV 能区内的能量响应(以~(60)Coγ射线的响应归1)<±5%;在上述能区内,当照射量率为10mR/h时,校准因子的总不确定度(一倍标准差)估计为±0.9%,在近一年内的长期稳定性<±1.2%。该电离室于1987年 IAEA 关于次级标准实验室校准程序亚太地区比对研讨会期间与 IAEA 剂量实验室比对,在上述能区内与本实验室校准结果在1.2%内相符。     

用γ射线衰减技术测量两相流中空泡份额精度的试验研究

一、引言用γ射线衰减技术测量两相流中的空泡份额,方法简单,应用最为广泛,并常以它来对其它测量方法进行标定,因此它的测量精度就十分重要。对于一次测量法,在空泡份额>10%的情况下认为可达±5%,而实际上一般取为±10%。     

直流电流传感器高精度校准系统设计

直流电流传感器（DCCT）的测量精度是高精度直流稳流电源输出电流精度的关键影响因素之一。针对DCCT优于1×10^-5的电流测量精度，本文提出了一种通过用高准确度的直流比较仪（DCC）测量电阻原理设计的校准系统，可实现DCCT 0~400 A测量范围内的高精度校准，且在整个校准范围内系统测量的相对不确定度优于1.1 ppm。通过实验测试DCCT的准确度和线性度验证了整个校准系统的精度，为进一步提高磁铁电源的电流精度提供了保障。     

精密钛涂层测厚仪

本文介绍一种用微机控制的精密钛涂(镀)层厚度测定仪,测量范围为0.1—10μm,最小测量面直径为3mm,精度优于±5％。     

直流电流传感器高精度校准系统设计

直流电流传感器(DCCT)的测量精度是高精度直流稳流电源输出电流精度的关键影响因素之一。针对DCCT优于1×10~(-5)的电流测量精度,本文提出了一种通过用高准确度的直流比较仪(DCC)测量电阻原理设计的校准系统,可实现DCCT 0～400 A测量范围内的高精度校准,且在整个校准范围内系统测量的相对不确定度优于1.1 ppm。通过实验测试DCCT的准确度和线性度验证了整个校准系统的精度,为进一步提高磁铁电源的电流精度提供了保障。     

微弱电离电荷校准系统构建

为了更加准确地校准微弱电离电荷,设计、构建了微弱电离电荷校准系统。该系统由静电计6517B、高压源2410-C和标准电容等仪器搭建。测试结果表明:灵敏度约等于1;测量电荷与采集电荷的线性相关系数为1;短期稳定性为0.1%,长期稳定性在0.3%左右;测量结果的不确定度不大于3.06×10-5(k=1)。     

20000克镭当量Co~(60)γ辐射源装置的辐照样品温度控制系统

本文报导了20000克镭当量Co~(60)γ辐射源装置的辐照样品温度测量控制系统.温度测量控制范围从-196℃到±250℃.精度平均为±0.5℃.整个系统都是利用国产仪器设备或经过改装的仪器构成的.目前,它已应用于辐射化学研究中,并证明其性能良好.     

铁品位分析仪的研制

铁品位分析仪配上小型压片机可用于铁矿粉中铁含量的快速测量,其测量一次时检测精度达到小于±０．５％的水平。     

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.     

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.     

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。     

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.