基于ASIC的GEM自触发电子学系统研制

针对同步辐射衍射探测的需求,设计了一套应用于三层GEM的自触发电子学系统。介绍了此电子学系统的整体架构、系统主要插件的电路设计、FPGA内部逻辑及算法的实现,以及与相应探测器配合的自触发读出方案。最后给出电子学系统初步调试结果。     

小型多参数程控记录仪

针对恶劣环境下信号测试的实际需要,设计了一种通用、灵活的小型多参数程控记录仪。以PIC16F877A单片机和复杂可编程逻辑器件(CPLD)组成的双控制器为核心,实现了对采样频率、触发值、存储长度等参数的可编程设置。USB和SPI双通信接口的设计使系统更具有可扩展性。针对单点测试,可灵活地根据被测信号和应用环境的特殊要求来设定参数并有效记录存储数据。在场测试中,可多点分布并在不同参数下协同工作,以获取尽可能多的场信息。经系统试验,该设计方案切实、可行。     

单光电子谱测试中触发方式对比研究

光电倍增管(PMT)单光电子谱测试中触发方式的对比研究对PMT性能刻度具有很强的指导意义。通过搭建自触发、同步触发、异步触发三套测试系统,对比研究不同触发方式对PMT性能刻度的影响。实验结果表明:自触发只可用于初步性能刻度;而异步触发在信号触发频率小于触发门采样频率时,得到多光电子谱,刻度结果远偏离实际值;同步触发方式能更可靠地刻度出更多更精确的PMT参数,是PMT性能刻度的最佳触发方式。     

多通道同步高速数据采集系统研制

介绍了一个最高采样率为100MHz，采样精度为8bit，基于PCI总线和计算机并口的8通道同步高速数据采集系统的设计，整套系统具有同步误差小、触发方式多样、操作灵活等特点。     

超级神冈中微子的强制触发模块设计

使用强制触发的方法,清华大学高能中心的研究人员首次在日本超级神冈实验的纯水探测介质中观察到了中子俘获寿命曲线.本文讨论强制触发的实现原理和强制触发电子学模块的具体设计,并对实验过程和结果进行了讨论.     

4π BaF2装置的触发系统研究

设计了一套γ全吸收型BaF₂探测装置,用于中子辐射俘获反应截面的在线测量,其中信号测量部分采用了基于高速采集卡的数字化脉冲波形采集技术。并设计了一套触发系统,由触发单元产生的信号作为数据获取系统的外触发控制数据采集,以在数据测量过程中剔除绝大多数本底事件。触发系统采用了符合测量技术,通过多通道、多参数之间的符合测量,实现释放瞬发级联γ射线的中子俘获反应事件的判选和本底的剔除。本文对触发系统的电路设计和实验测试进行了阐述。     

α/β放射性气溶胶的小流量采样快速测量技术研究

针对放射性气溶胶监测仪的便携要求,设计了一套小流量采样快速测量系统和测量方法。采用累积采样累积测量的方式,联合利用能量甄别修正法与α/β比值法去除Rn子体的干扰,实现小流量采样条件下的α/β放射性气溶胶的同时监测。通过对探测下限的分析,表明该方法可满足应急监测的需求,为便携式α/β放射性气溶胶监测仪设计提供了参考。     

塑闪单元条测试系统标定触发电路设计

为记录和分析塑闪阵列探测器(PSD)中塑闪单元条的有效输出信号,设计一款针对PSD塑闪单元条的标定触发电路。该触发电路由时间检出单元和逻辑触发单元组成,使用三路模拟电路实现对三路探测器的精确时间检出。通过现场可编程门阵列(FPGA)进行逻辑符合统计结果,并与上位机通信实现对定时电路的控制,可通过上位机配置阈值和设置符合通道。测试结果表明:该标定触发电路工作性能稳定,计数率高,通道一致性好,能够灵活配置逻辑,可满足使用要求。     

福清核电站余热排出泵漩涡探测报警触发分析

文章介绍了福清核电站余热排出系统漩涡探测装置设置的目的以及报警触发后的动作,及当前设计上为避免泵入口出现漩涡已采取的措施;并结合福清核电机组在满足设计所需采取的措施的前提下触发该报警的现象,详细介绍了该报警触发的经过并结合机组当时的工况分析其原因及漩涡探测触发的机理;分析了该报警触发后所需的响应和可能产生的影响,并最终提出余热排出泵在运行时避免出现漩涡的解决办法。     

一种基于FPGA的高精度单周期TDC设计

设计了一种基于FPGA的高精度TDC,通过延迟链插值和多沿采样等方法,达到与全定制专用集成电路相同的时间精度,实测结果好于9 ps.采用多路选择器阵列和加法器构造的编码器将转换死时间降低到1个时钟周期.设计还使用了自校准的机制,增加了可移植性,可广泛应用于粒子飞行时间探测、核医学影像等领域.     

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。     

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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