用于~(16)C核集团结构实验研究的望远镜探测器阵列性能研究

对16C核集团结构实验研究中使用的望远镜探测器阵列的性能进行了研究,此望远镜阵列主要用于靶后反应产物的探测及粒子鉴别。探测器阵列由9组望远镜组成,其中包括了硅微条、位置灵敏硅探测器(PSD)、大面积硅探测器(SSD)和CsI探测器单元在内的多种类型的探测器。用241Amα源对组成望远镜的各探测器进行了测试和优化,且在中国科学院近代物理研究所的重离子加速器放射性次级束流线(RIBLL)上进行了在束测试。结果表明,研制的望远镜探测器阵列具有较好的能量分辨、高的角分辨及粒子鉴别能力,可满足通过碎裂反应来研究16C等原子核的集团结构的需要。     

利用MCNP程序对充气电离室探测性能的研究

利用MCNP程序研究了充气电离室的探测径能，计算了探测器内工作气体和电扳片在射线探测中各自的作用，得到该电离室的探测效率．然后计算不同偏角入射时探测器的信号输出值，并给出计算的探测灵敏废。计算结果表明，高压充气电离室探圈^60Co源γ射线也可达到高的探测效率和灵敏度．     

批量塑闪单元条测试技术的研究

寻找暗物质粒子是目前最有影响力的前沿课题之一,广泛受到世界各国重视。我国启动了暗物质粒子探测卫星(Dark Matter Particles Explorer,DAMPE)先导专项,致力研究这一科学问题。暗物质粒子探测卫星有效载荷由塑闪阵列探测器(Plastic Scintillator Detector Array,PSD)、硅阵列探测器、BGO(Bi2O3-Ge O2)量能器以及中子探测器组成,用于探测5 Ge V-10 Te V高能电子、γ及重离子能谱。中国科学院近代物理研究所承担了塑闪阵列探测器的研制工作,塑闪阵列探测器由82根塑闪单元模块采用横竖交叉结构组成,主要协助BGO量能器区分γ事件和电子事件,并作为硅阵列探测器的备份,探测Z=1-20的重离子事件。由于塑闪单元条模块存在较大的差异,所以搭建了一套具有较高测试效率的塑闪单元条批量测试平台,并对塑闪单元条进行宇宙线测试,得到其基本性能参数,如光衰减曲线、光衰减长度、相对光产额、能量分辨率以及探测效率。这为后续筛选出一致性较好并能满足功能需求的82根单元条提供了依据。     

大面积光纤阵列探测器探测单元性能的进一步测试

对大面积光纤阵列探测器中的光纤阵列探测单元的性能进行检测。测试了不同形状、不同材料的光导以及光导包裹不同反光材料时光纤探测单元的传输效率及时间分辨和位置分辨。确定了大面积光纤探测器探测单元所使用光导的材料和形状，给出了光纤阵列探测器探测单元可达到的时间分辨。     

硅光伏探测器探测α粒子研究

采用蒙特卡罗方法计算了硅光伏探测器探测α粒子的能量分辨率等参数,通过实验测得了其α谱和探测效率。实验表明,硅光伏探测器对α粒子具有较高的探测效率和能量分辨率,受β、γ射线影响小,非常适合用作α粒子探测器。     

大面积塑料闪烁体γ探测技术研究

使用大面积塑料闪烁体探测器对γ射线进行探测时会出现远离信号采集端的入射粒子探测效率低的现象,在对大面积塑料闪烁体探测器两端同时进行信号采集的基础上,使用加和器对两路信号加和的测量方法,明显提高了探测效率.     

Si-PIN型X射线探测器灵敏度的MC模拟

在能量色散X荧光仪设计过程中,探测器的尺寸、系统几何结构和目标元素等都涉及到探测器灵敏度的问题。论文从玻尔兹曼方程及电子输运Spencer-Lewis方程入手推导探测器灵敏度的理论计算公式,基于MCNP5模拟平台研究Si-PIN型探测器灵敏度变化规律。研究发现:Si-PIN型探测器灵敏度随探测器灵敏材料厚度的增加呈指数增长;随入射射线能量增加,其规律与探测效率曲线相同;当探测器与样品间的距离小于100 mm时,距离对探测器灵敏度的影响可以忽略。     

φ60mm×600μm硅PNI探测器γ灵敏度和时间响应测量

φ6 0 mm× 6 0 0μm硅 PIN半导体探测器是近年国内新研制的大面积高灵敏度探测器 ,用 10 13Bq级的 60 Coγ放射源测量了该类探测器的 60 Coγ灵敏度 ,用 CΓC脉冲辐射源 (约 0 .2 Me V)测量了该类探测器的时间响应。实验和理论计算表明 :该类探测器的 60 Coγ灵敏度约为 5 f C·cm2 / Me V。脉冲响应上升时间约为 10 ns,脉冲响应半高宽约为 35 ns。     

大面积阵列中子伽马甄别探测器的蒙特卡罗模拟研究

对特殊核材料的检测关乎国土安全,需要一个快速、安全可靠的辐射检测系统。采用Geant4蒙特卡罗模拟软件建立一套基于塑料闪烁体的大面积中子伽马探测系统。研究单根闪烁体晶体不同截面边长、多种层数结构以及不同natGd₂O₃包裹方式等探测器的关键参数,通过调整探测器的响应数目阈值评估探测器的n/γ甄别性能。结果表明,当采用截面边长为6 cm×6 cm的塑料闪烁体包裹25 μm厚的natGd₂O₃、探测器之间放置3 mm厚Pb板以及探测器响应数目阈值设置为3时,阵列探测器可以达到约23%的中子探测效率以及约802的n/γ甄别比。计算结果可对大面积阵列探测器的关键参数优化提供理论依据。     

受控热核聚变装置软X射线反演成像探测研究

介绍了探测系统的角向分辨率、径向分辨率、探测器空间分辨率、探测器阵列空间分辨率和探测系统的时间分辨率的设计原则。其角向分辨率由探测阵列数目决定．其径向分辨率由阵列中探测器数量决定。根据装置的具体条件,研制专用的条形探测器可以获得最佳的探测器空间分辨率和探测器阵列空间分辨率。研制宽频带放大滤波电路系统可以保证高时间分辨率。高质量反演探测系统可采用多角度多阵列方式或在刚体旋转假设下采用完美的单阵列方式。小装置上的高灵敏的反演成像探测系统可在中心电子温度约150eV,电子密度约10^15cm-3的低参数条件下探测到稳定信号并完成图像反演。     

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.     

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.     

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.