超短脉冲X射线激发荧光寿命谱议的设计与研制

介绍了一种超短脉冲X射线作为激光光源，用时间关联单光子计数法进行,测量的荧光衰减时间谱仪的设计与研制。该仪器具有时间分辨率高、测量动态范围大、使用方便等优点，可应用于晶体、粉末和液体等各种样品的测量，该仪器同时还具有很强的扩展性。     

弱电流测试仪的研制

介绍了最近研制的弱电流测试仪，它的原理和设计要点。该仪器是一 便携式弱电流测试仪，可以测量10^-10-10^-4A范围的弱小电流。该仪器具有测量精度高、工作稳定、结构简单、便携等优点。     

数字化反应堆物理启动仪器的研制

研制了一套数字化的反应堆物理启动仪器,该套仪器主要由探测器、数据采集电路、微型计算机及计算机数据处理软件组成,其中数据采集电路包括脉冲放大电路及计数器电路、多量程微电流放大电路及模数转换电路、数据传输电路。该仪器能够完成次临界外推、超临界内插、中心控制棒效率测量及径向燃料元件效率测量等实验。在微堆低浓化零功率实验中对该仪器的测量功能进行验证,实验结果验证了该仪器测量的准确性。     

基于高精度时间分辨技术的四路低本底αβ测量仪研发

为了提高仪器性能,开发了一款新型的总α总β低本底测量仪,与传统的信号幅度区分方式不同,仪器采用高精度时间分辨技术能够更准确地区分α信号和β信号。通过各项性能指标测试表明,仪器性能指标优越。测量室采用新型结构设计,具有高灵敏、小型化、数字化及允许脱机自主工作等特点,测量缓存机制保证了断电情况下的数据完整性,适用于αβ放射性活度的长时间稳定测量。     

脉冲堆启动时间测量仪

研制了启动时间测量仪。该仪器通过光电传感器检测控制棒到达堆体内限位置的时刻,通过闪烁探测器探测脉冲堆功率,用于测量脉冲堆控制棒快速插入堆体内限到堆爆发脉冲功率达到某预选水平时的时间间隔。仪器采用Intersil ICM7226B芯片实现计数器和显示驱动功能,时间测量范围分为5档,具有8位数字显示。启动时间测量仪经过多次实验应用,测量结果满足相关物理实验研究的需要。     

脉冲时间序列采集分析器的研制与验证

介绍了脉冲时间序列采集器(TSA)的研制及实验验证。该仪器采用FPGA和DSP技术实现了三通道并行、最高定时精度5ns、最高计数容量109的脉冲序列采集存储。根据Rossi-α原理编制软件算法实现了在线和离线测量。该仪器应用于核装置瞬发中子衰减常数测量的实验验证,测量结果与Rossi-α测量结果一致。     

脉冲堆启动时间测量仪

研制了启动时间测量仪.该仪器通过光电传感器检测控制棒到达堆体内限位置的时刻,通过闪烁探测器探测脉冲堆功率,用于测量脉冲堆控制棒快速插入堆体内限到堆爆发脉冲功率达到某预选水平时的时间间隔.仪器采用Intersil ICM7226B芯片实现计数器和显示驱动功能,时间测量范围分为5档,具有8位数字显示.启动时间测量仪经过多次实验应用,测量结果满足相关物理实验研究的需要.     

脉冲时间序列采集分析器的研制与验证

介绍了脉冲时间序列采集器(TSA)的研制及实验验证.该仪器采用FPGA和DSP技术实现了三通道并行、最高定时精度5ns、最高计数容量109的脉冲序列采集存储.根据Rossi-α原理编制软件算法实现了在线和离线测量.该仪器应用于核装置瞬发中子衰减常数测量的实验验证,测量结果与Rossi-α测量结果一致.     

基于QTC(电荷测量)技术的γ能谱仪的研制

基于QTC(电荷测量)技术的新型轻便式γ能谱仪的研制,包括仪器的系统结构原理、硬件和软件设计特征。并通过系统的实际测试结果,证明该新型γ能谱仪具有高精度的谱线测量、方便的数字化控制、突出的测量精度指标等优秀的综合技术指标。     

ZF-102S工具污染监测仪的硬件设计

本文介绍了ZF—102S工具污染监测仪的组成、电路原理设计和主要性能测试。该仪表选用两套大面积塑料闪烁体+PMT作为探测器,采用智能单向测量流程,测量腔室外加铅屏蔽,可在复杂环境下有效测量待测工具的γ放射性水平。试验结果表明:在条件为本底0.2μGy/h,测量时间60 s,置信度为95%,仪器最低可探测限小于100 Bq(参考源~(60)Co)。仪表具有长短工具两种测量模式,大容量蓄电池在仪器断电后持续工作超过3 h。     

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。     

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.     

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.