几种常用闪烁体受60Coγ源辐照前后探测器灵敏度比对

在闪烁体耐辐照特性研究中,通过比较闪烁体受辐照前后闪烁探测器系统灵敏度的变化,说明在大辐照剂量后闪烁探测器是否处于正常工作状态.利用三通道脉冲X射线源(平均能量800keV)、DPF脉冲中子源(D-T中子能量14.4MeV),通过实验标定几种常用闪烁探测器对脉冲中子、脉冲X射线的相对灵敏度值.所用闪烁体包括φ40mm,不同厚度的CeF3,NaI(T1)和BaF2等无机晶体及ST-401,ST-1422,NE111等塑料闪烁体.     

几种常用闪烁体受^30Coγ源辐照前后探测器灵敏度比对

在闪烁体耐辐照特性研究中,通过比较闪烁体受辐照前后闪烁探测器系统灵敏度的变化,说明在大辐照剂量后闪烁探测器是否处于正常工作状态。利用三通道脉冲X射线源（平均能量800keV）、DPF脉冲中子源（D-T中子能量14．4MeV）,通过实验标定几种常用闪烁探测器对脉冲中子、脉冲X射线的相对灵敏度值。所用闪烁体包括Ф40mm,不同厚度的CeF3,NaI（T1）和BaF2等无机晶体及ST-401,ST-142Z,NE111等塑料闪烁体。     

φ76mm×100mm BGO闪烁探测器在20 MeV以下能区的能量响应

用上海硅酸盐所提供的φ76mm×100mm BGO晶体制作γ闪烁探测器、用来探测???离子核反应中放出的10-100 MeV的γ射线,该探测器对~?Cs的0.661 MeV γ射线的?????14.2%。在加速器上用若干(p,γ)反应产生的单能光子测试探测器的能量响应,通过细致的数?拟合得到该探测器在20 MeV以下能区的能量响应和全能峰能量分辨率。对17.65 MeVγ射线。探测器的能量分辨率为4.1%。     

厚入射窗真空康普顿探测器设计

利用γ射线与物质作用的康普顿散射效应,设计了用于强流脉冲γ射线测量的具有厚入射窗真空型康普顿探测器。前窗采用厚度4.5 mm的Al,易于机械加工、真空除气和真空保持。收集极为φ50 mm×5.6 mm的Fe,对于1.25 MeV的γ射线,探测器灵敏度的设计值为4.5×10-22C/MeV。     

硅PIN光敏二极管探测X、γ射线的性能及应用

介绍了硅PIN光敏二极管和电荷灵敏前放组成的X射线探测器和配合CsI(Tl)晶体构成的γ射线探测器的性能和测量结果,同时研究了光敏二极管探测器能量分辨率的温度特性。测量X射线时,在-10℃下对241Am的59.5keV射线的能量分辨率为4.8%;用PIN光敏二极管配合10mm×10mm×10mm的CsI(Tl)晶体测量γ射线时,在20℃下对137Cs0.662MeVγ射线的能量分辨率为9.9%,60Co的1.332MeVγ射线的能量分辨率为6.4%,-10℃下的能量分辨率分别为8.7%和6.3%。     

闪烁体-光纤组合式辐射探测器γ相对灵敏度研究

根据光纤光导的耦合理论,推导了闪烁体-光纤组合式探测器γ灵敏度理论公式,计算了LSO、 ST401两种闪烁体-光纤探测器的相对灵敏度,在平均能量为1.25 MeV的60Co射线源上测得10 mm厚LSO闪烁体-光纤组合式探测器的灵敏度是相同厚度ST401的19倍,理论计算和实验结果在不确定度范围内一致.     

用于X射线探测的CVD金刚石薄膜探测器

研制了用于X射线测量的化学气相沉积(CVD)金刚石薄膜探测器.该探测器灵敏区直径为15 mm、厚度300 μm,其暗电流在800 V偏压下小于50 pA,且暗电流-电压曲线线性较好.就CVD金刚石探测器对不同能量X射线的响应及脉冲X射线时间响应进行了理论和实验研究.结果表明:该探测器对6～22 keV X射线具有10-4～10-2A·W-1的灵敏度,假设电荷收集效率为39%时,灵敏度的理论值与实验测量值符合较好,探测器的RC时间常数约为1.5 ns;对亚纳秒脉冲X射线的响应上升时间为2～3 ns.     

CeF3晶体伽玛能响及抗中子能力研究

用Monte Carlo和核物理理论分析的方法研究了CeF3晶体对γ射线的能量响应趋势,并通过实验测量了CeF3晶体与光电倍增管组合构成的闪烁探测器对不同能量的中子和γ射线的灵敏度。结果表明:CeF3晶体在0.3～0.9 MeV能区具有较平坦的γ能量响应曲线,较强的抗中子干扰能力。     

闪烁薄膜探测器X/γ射线能量响应研究

为准确评估闪烁薄膜探测器(OSFD)在脉冲裂变中子参数测量中γ射线对测量结果的影响,利用Geant4程序对闪烁薄膜探测器的X（或γ）射线响应进行模拟,结合半经验电子发光效率曲线,获得探测器能量响应理论曲线,利用662 keV和1.25 MeV的单能γ射线源,以及窄谱剂量标准的48~208 keV准单能X射线能点对探测器响应进行刻度。本研究结果为闪烁薄膜探测器结构的改进,以及探测器在宽能谱脉冲X射线场测量中的应用提供了重要依据。     

φ60mm×600μm硅PIN探测器γ灵敏度和时间响应测量

φ60mm×600μm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1013Bq级的60Coγ放射源测量了该类探测器的60Co γ灵敏度,用CΓC脉冲辐射源(约0.2MeV)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60Co γ灵敏度约为5 fC*cm2/MeV.脉冲响应上升时间约为10ns,脉冲响应半高宽约为35ns.     

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.