三双符合比-切伦科夫方法中β核素壁效应的影响

为分析三双符合比-切伦科夫(TDCR (Triple-to-double Coincidence Ratio)-切伦科夫)方法中壁效应对效率计算的影响。首先，对β粒子在溶液到瓶壁过程的输运进行分段分析，得到不同能量的粒子在不同材料中的沉积能谱与所产生的切伦科夫光子数的关系式，并对其进行了计算上的简化，进一步完善TDCR-切伦科夫效率的计算模型；之后利用Geant4计算了β在介质和瓶壁中的沉积谱，得到考虑了壁效应的切伦科夫光子数与β能量的关系曲线以用于对核素的效率计算；最后开展了多种纯β核素的实验测量以验证考虑壁效应后的计算模型的准确性。结果显示：考虑壁效应后的TDCR-切伦科夫方法与液闪方法的结果在不确定度范围内一致，且对高能β核素，其结果与液闪之间的相对偏差由原方法的0.47%降低至0.02%(⁹⁰Y),0.64%降低至-0.16%(32P)，表明考虑壁效应后的TDCR-切伦科夫方法对高能β核素的测量结果更准确。     

STCF RICH原型探测器的测试电子学系统构建与联调测试

环形成像切伦科夫（RICH）探测器作为超级陶粲装置（STCF）带电强子(π/K/p)鉴别的技术选项之一,采用厚型气体电子倍增器+微网格气体（THGEM+Micromegas）混合探测器结构以实现对切伦科夫光的探测。针对RICH原型探测器的信号读出,构建了一套1 024通道测试电子学系统,并与探测器进行了联合测试。该测试电子学系统使用高密接插件与RICH原型探测器进行连接,探测器输出信号通过测试电子学系统上的AGET和ADC芯片进行放大、成形和波形数字化,输出的数据经FPGA处理后通过千兆以太网传输至后端PC并进行数据分析。测试结果表明,在120 fC输入动态范围下,系统的等效噪声电荷（ENC）小于0.3 fC,且具有良好的输入-输出线性。该系统成功应用于RICH原型探测器切伦科夫成像束流实验中,并取得了良好的切伦科夫光成像结果。     

STCF RICH原型探测器的测试电子学系统构建与联调测试

环形成像切伦科夫(RICH)探测器作为超级陶粲装置(STCF)带电强子(π/K/p)鉴别的技术选项之一,采用厚型气体电子倍增器+微网格气体(THGEM+Micromegas)混合探测器结构以实现对切伦科夫光的探测。针对RICH原型探测器的信号读出,构建了一套1 024通道测试电子学系统,并与探测器进行了联合测试。该测试电子学系统使用高密接插件与RICH原型探测器进行连接,探测器输出信号通过测试电子学系统上的AGET和ADC芯片进行放大、成形和波形数字化,输出的数据经FPGA处理后通过千兆以太网传输至后端PC并进行数据分析。测试结果表明,在120 fC输入动态范围下,系统的等效噪声电荷(ENC)小于0.3 fC,且具有良好的输入-输出线性。该系统成功应用于RICH原型探测器切伦科夫成像束流实验中,并取得了良好的切伦科夫光成像结果。     

用液体闪烁谱仪对~(32)P进行切伦科夫计数

液体闪烁谱仪一般用于测量含有~3H、~(14)C等低能β放射性核素的样品。当电子能量超过263keV时,在水中就能产生切伦科夫辐射。~(32)P β粒子的最大能量为1.7MeV,是理想的切伦科夫辐射源。我们用液体闪烁谱仪进行切伦科夫计数时,为确定最佳介质体积,提高计数效率,研究了~(32)P在几种介质中的计数效率与介质体积的关系。     

基于切伦科夫探测器的高能双能X射线物质有效原子序数检测

介绍了采用切伦科夫探测器在高能双能X射线物质有效原子序数检测中的应用优势。采用电子加速器产生的X射线源的双能物质有效原子序数检测中,由于能量较低的X射线(低于0.5 M eV)占有重要的份额,其光电效应的存在干扰物质有效原子序数的检测,故一般需要加滤波材料降低其数量从而改善检测效果。切伦科夫探测器由于对X射线有探测阈值要求,可以不用加滤波材料即可实现物质检测功能;另外,对高能X射线有更好的相对能量响应是其在此方面应用的另一个优势。通过在一个双能检查系统(采用6 M eV和3 M eV电子加速器)的实验证明了这种设想,实验结果和预期的设想以及模拟计算结果相吻合。     

γ灵敏切伦科夫光纤阵列探测器的γ/n分辨能力研究

在脉冲辐射混合场(n,γ)中进行γ射线参数测量,要求探测器系统必须有很快的时间响应,还应有很高的γ/n分辨能力。本文详述了切伦科夫(Cherenkov)辐射原理,用蒙特卡罗软件MCNP模拟计算了γ、中子在不同光纤阵列材料中的能量沉积,根据计算结果选择铅玻璃作为光纤阵列切伦科夫辐射体,配合常聚甲基丙烯甲酯(polymethylmethacrylate,PMMA)塑料光纤光导传输,由光电倍增管转换为电信号输出,研制了一种γ灵敏切伦科夫铅玻璃光纤阵列探测器。在中国原子能科学研究院的600 k V高压倍加器上进行了14.1 MeV中子灵敏度实验,又在西北核技术研究所60Co源上完成了1.25 MeVγ灵敏度实验。实验数据与模拟结果推算得出的数据基本相符,表明该探测器系统具有较高的γ/n分辨能力,可满足在脉冲中子、γ辐射混合场中对γ射线参数测量的分辨能力要求。     

基于嵌入式系统的LHAASO WCDA中TCP/IP数据传输接口设计

针对大型高海拔空气簇射观测站水切伦科夫探测器阵列,开展了前端电子学数据传输接口设计。基于实验数据率大、数据可靠性要求高的特点,进行了千兆以太网下的TCP/IP数据传输模块的设计。本文主要介绍了基于FPGA嵌入式系统的TCP/IP数据传输技术在LHAASO WCDA中的应用研究。实验结果表明:此数据传输模块数据率可达237 Mbps,满足应用要求。同时,还对此模块进行了24小时的传输测试,数据传输率保持稳定。     

大气切伦科夫望远镜中的探测器系统

本文介绍兴隆站大气切伦科夫望远镜中的探测器系统，测量了抛物面反射镜的反射效率和光电倍增管磁屏蔽的效果，给出了测得的宇宙线切伦科夫光的幅度谱。     

切伦科夫光:纳米核药物诊断治疗一体化的新光源

切伦科夫光是放射性核素衰变过程中的发光现象，在生物医学领域受到越来越多的关注。切伦科夫光的可见光波段可以直接被相机捕获实现切伦科夫成像，有望运用于术中导航。同时，切伦科夫光在此过程中作为体内光源的性质也受到关注，将核素作为体内光源结合纳米颗粒进行光动力治疗可以取得较好的肿瘤抑制性。但是由于切伦科夫光的发光效率极低，相关研究仍存在争议，其可能并不是仅有切伦科夫光起作用的结果。虽然切伦科夫光在生物医学领域具有独特运用，但其较低的发光效率是限制其发展的关键因素。基于纳米颗粒-核素相互作用的体系则可解决这一问题，为进一步拓展切伦科夫光在生物医学研究中的应用奠定基础。     

羊八井水切伦科夫探测器阵列分布式电子学系统原理验证

讨论了羊八井大型高海拔宇宙线探测实验(Large High Altitude Air Observatory,LHAASO)的水切伦科夫探测器阵列(water Cherenkov detector array,WCDA)分布式电子学系统原理。并设计了一个包括两个原型模块的原理验证电子学系统,用于验证相关原理,包括远距离大范围时钟分配方案和回声原理的校准方法。测试结果表明分布式电子学原理满足WCDA实验需求,并将运用到实际工程设计中。     

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.