上海光源150MeV直线加速器传输波导相长度测量与调整

上海光源直线加速器加速器主体由电子枪、次谐波束聚器、基波聚束器及四台加速管组成,其功能是通过低能输运线向增强器注入150 MeV能量的电子束.直线加速器2006年12月开始安装,2007年5月出束,10月完成束流调试,向增强器供束,束流指标达到设计目标.传输波导相长度的测量与调整是微波系统及加速器建设安装过程中的的关键环节,调试结果直接关系到直线加速器的升能效果,影响到束流其它相关参数.本文阐述了上海光源直线加速器波导相长度测量与调整过程,给出了加速器束流调试的相关指标结果.     

等离子喷涂硼化镧阴极电子枪

一、引言现代大型医用电子直线加速器电子枪的设计有如下特点: 1.要求电子枪束流在大范围内连续可调。对于一个二极型电子枪系统,枪必须工作在温度限制区域内,故阴极发射的稳定性十分重要。2.行波电子直线加速器通常采用可拆性结构,这就要求阴极必须有较好的抗中毒特性。     

SSRF电子枪控制系统的设计与实现

电子枪是上海光源SSRF(Shanghai Synchrotron Radiation Facility)中的直线加速器的关键部件,上海光源的束流品质很大程度上取决于电子枪的束流指标,因此电子枪需要一个稳定的控制系统来保证其可靠运行.本文介绍了上海光源电子枪控制系统的设计与实现过程.该系统底层采用可编程控制器PLC(Programmable Logic Controller)作为设备控制器,上层监控软件使用加速器控制系统通用软件EPICS (Experimental Physical and Industrial Control System),整个控制系统基于以太网连接.PLC和以太网技术的应用,使该系统具有可靠性好、易于维护等特点.     

NDZ-20医用电子直线加速器的注入系统

文章介绍了NDZ-20医用电子直线加速器的束流注入系统的结构和特性。电子枪为轰击型的皮尔斯电子枪。漂移管上的预聚焦线圈、偏掉线圈、导向线圈和束流前沿切割线圈用来实现对电子束的多种控制,实现加速器的ARC,ADC和BLC运用,以保证加速器运行的稳定性和可靠性,改善反馈加速器的能谱。     

宽范围高精度电子枪系统的设计与验证

“空间环境地面模拟装置”是“十二五”国家重大科技基础设施项目,针对其子项目“低能电子加速器及束线”中辐照加速器的要求,在原有二极电子枪基础上增加了控制栅极。使用CST Particle Studio仿真研究了电子枪部分结构参数变化对引出束流强度的影响,设计出产生50 mA高品质束流的电子枪,并用PBGUNS(Particle Beam GUN Simulation)软件对设计结果进行验证。最后在电子枪实验平台上检验了电子枪结构参数变化对引出束流强度的影响规律,并对电子枪结构进行了优化。结果表明优化后的电子枪能够以阴极初级加热电压作粗调、栅极电压作细调的方式引出1μA～50 mA高品质电子束。     

新型电子直线加速器测试与改进

一种新型的省略电子枪的小型直线加速器被研制成功。高功率速调管的用毕束流被引出作为注入电子,从而取代了传统的电子枪部分。装置在调试完成后开始运行,我们对获得加速后的电子束性能做了初步测量,并与模拟结果进行了对比。结果表明,加速器输出流强远低于设计目标。运用Parmela程序详细分析了电子束流损失的主要因素,针对减少束流损失,提高加速器输出流强,提出了新的改进方案。通过计算分析,得出了该方案良好的可行性。     

强流栅控电子枪设计分析

电子枪是超高真空电子器件,可用于各类加速器的束流源与功率源中,是加速器与微波电子管的主要与关键部件之一.结合某辐照加速器电子枪实际需要,对其束流光学系统进行了计算机模拟和优化设计.模拟结果表明该电子枪在80 kv高压下工作时,输出电流可以达到5 A以上,束流发射度、枪区电场以及束腰半径可以满足该加速器运行的需要.电子枪...     

可更换阴极热子的辐照加速器用电子枪

本文介绍了工作电压为60 kV、峰值电流为550-600 mA、射程要求为60 mm、注腰不大于Φ4 mm的电子枪的研制.该电子枪用于辐射加工电子直线加速器(10 MeV 1.5 mA).为降低加速器的运营成本,该电子枪特别设计为可更换阴极热子型.采用Egun、Mafia等软件进行模拟计算,基本按照速调管生产的工艺流程...     

准周期聚焦-加速耦合系统的‘均温’设计方法(英文)

强流质子直线加速器要求严格控制束流损失和束流发射度增长。理论已经证明,强的空间电荷作用在不同自由度之间的耦合,会因为其间的‘温度’差异,通过束流的相干不稳定性,使束流发射度增长。因此,有必要按照‘均温’的原则设计强流加速器。但是,由于质子直线加速器的各种加速结构均为准周期耦合系统,使得‘均温’设计十分繁琐而难以达到完全‘均温’。利用国际上通用的束流动力学软件TRACE3-D,给它补充了‘均温’设计功能,通过与PARMILA程序的配合使用,可以方便地在加速器设计中实现‘均温’条件。介绍了对TRAcE3-D的修改补充,并以强流质子直线加速器设计实例,说明均温设计的必要性。     

NFZ-10工业辐照电子直线加速器束流控制方法

在ＮＦＺ－１０工业辐照电子直线加速器上，分析了以输出束流来负反馈控制轰击型二极电子枪灯丝电压进而稳定输出束流的方法及存在的缺点。提出了新的控制轰击高压的方法，在此加速器上得到了高稳定性和高精度的输出束流。     

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.