高性能微电流集成放大器的设计

介绍了用ICL7650运算放大器设计高性能微电流集成放大器的方法,阐述了电路的工作原理和提高放大器性能的措施,给出了实际应用的实验结果。该放大器测量范围10^-9～10^-12A,自换量程,自动校零,测量准确,工作稳定。     

REM-Ⅱ型氡析出率仪的研制

介绍了一种可携式介质表面氡析出率仪，该仪器用静电收集探测室对氡衰变的218Po所释放的α粒子脉冲计数进行测量，用φ50mm金硅面垒探测器，计数容量999 999，测量范围10^-5-10^2Bq/m^2.s，仪器有两种工作方式以适应高低不同析出率范围的选择测量，可改变参数设置，计数自动显示，数据存储与结果打印等功能。     

长时间电流积分数字仪的设计

本文介绍的长时间电流积分数字仪,是用电流-频率(I-F)转换电路将微弱电流转换成脉冲信号,结合后级脉冲计数器及处理控制电路,实现对10pA-10μA量级输入电流的长时间测量。该仪器可用于电离室、法拉第筒等输出电流或电荷的测量,测量时间范围1s-192h。该电路的设计实现,为长时间测量电流或电荷,并进行束流监测提供了一种可行、通用、高性价比的好方法。     

微弱电流的测量与I/F变换电路的设计

介绍了反馈式电流放大器型I／V转换和V／F变换电路的设计,详细讨论了减少噪声干扰的措施。可以测量10^-11～10^-6A的弱电流。     

用于ADS启明星1#中子涨落特性测量的微电流放大器研制

通过对次临界反应堆中子噪声特性的分析,设计了一种能反映ADS系统启明星1#实验装置中子涨落特性的微电流放大器。通过设计和调试,该放大器能够实现10^-9－10^-11A的电流－电压通频带转换放大,达到了设计的要求。     

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。     

离子收集式α探测器

文章叙述自行试制的１台ＤＬ－０１型α探测器。利用流动空气将α粒子在空气中产生的电离离子送入离子电离室内进行电流测量，电流值的大小与α源活度成比例，流动空气可将离子传送至数十厘米甚至数米以上。该探测器的电流探测限为３５ｆＡ，灵敏度为（６．６６±０．１２）ｆＡ／Ｂｑ，在较宽的活度范围内，探测器有较好的线性。对在该装置上进一步降低本底电流及增加本底电流的稳定性、防止空气尘埃对电离室的污染、刻度仪器用α辐射源的选择等问题进行了讨论。仪器的刻度问题、污染物的大小以及不同部位的污染对测量结果所带来的影响等问题有待进一步研究。     

变温法测量贮氢材料-氢系P-C-T曲线

描述了采用变温法测量室温下平衡压为10^-3～10^-5Pa量级、易于毒化的贮氢材料－氢系P－C－T曲线的测量原理、装置和具体测试步骤等，并通过测量贮氢材料－氢系P－C－T曲线检验了变温法的操作可行性，同时对变温法的特点和存在的问题进行了初步分析。     

Stability Analysis of Some Nonlinear Feedback Control Methods for Beam Halo-chaos Suppression

^151Sm（半衰期90a）属于稀土元素，它在工业、农业、国防等应用研究中占有重要地位，研究其对环境和人体健康的影响非常重要。因其在样品中、尤其在生物样品中含量很低（只有10^-6～10^-9），所以加速器质谱（AMS）成为实现其高灵敏测量的有效方法。AMS测量要求离子源引出的束流尽可能大而且稳定，通过选择合适的负离子可以降低同量异位素的干扰。     

MSV-5型综合测试仪

为了在野外设备简陋的条件下,能够快速准确地检修和调整野外常用放射性测量仪器,我们特自制和装配了MXV-5型综合测试仪。现将该仪器的特点、用途和主要技术性能介绍如下。一、结构特点和用途 MSV-5型综合测试仪由脉冲讯号发生器、脉冲毫伏表、晶体管检验器、表头检测、可变电阻箱等五部分组成(图1)。在检查、校验野外放射性普查仪器时,该仪器可用于讯号     

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.     

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.     

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%。     

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.