Experimental verification of an APF linac for a proton therapy facility

Alternating phase focusing (APF) is known as a beam focusing method; it was applied to an interdigital H-mode structure and successfully accelerated high current proton beams up to the desired energy for a medical synchrotron injector. A high-current APF linac was achieved by the optimal design of the cavity and the drift tubes themselves, as well as drift tube arrangement based on the co-iteration of a precise electromagnetic field and space charge beam dynamics.A proton injector for a medical accelerator complex was fabricated with the newly developed APF linac. The injector consists of an electron cyclotron resonance ion source, a radio-frequency quadrupole linac and the APF linac. The experimental results showed that over 10 mA proton beams were accelerated up to 7.4 MeV.     

Development of an effective dose calculation method for the downstairs room of a linac facility

ABSTRACT

An effective dose calculation method is important in the design of efficient shields in radiation facilities. Some analytical methods have been shown to provide a simple and quick design analysis; however, no suitable method exists that can be applied to a room located directly under an X-ray irradiation room. We propose a new analytical method that uses the multiple reflection ratio predetermined by a Monte Carlo simulation and the differential dose albedo given by the Chilton–Huddleston semi-empirical equation. Our method is verified by comparison with the Monte Carlo simulation, performed for the case of an electron linac facility with an accelerated energy of 10 MeV, where the shielding floor has a thickness of 1.6–2.0 m and the downstairs room has a height of 0.5–1.5 m. The difference between the effective X-ray doses in the downstairs room calculated via the proposed analytical method and the Monte Carlo simulation is less than 25% when the horizontal distance from the X-ray beam to the evaluation point exceeds 3 m and the evaluation point is set at half of the height of the room. The new analytical method can be efficiently and accurately applied to the calculation of the effective dose.     

A 16-Channel high-resolution time and charge measurement module for the external target experiment in the CSR of HIRFL

High precision time measurement is required in the readout of the neutron wall and TOF walls in the ex- ternal target experiment of the Cooling Storage Ring （CSR） project in the Heavy Ion Research Facility in Lanzhou （HIRFL）. Considering the time walk correction, both time and charge are measured in the readout electronics. In this 16-channel measurement module, time and charge information are digitized by TDCs at the same time based on the Time-Over-Threshold （TOT） method; meanwhile, by employing high-density ASIC chips, the electronics complexity is effectively reduced. Test results indicate that this module achieves a time resolution better than 25 ps and a charge resolution better than 5% over the input amplitude range from 50 mV to 3V.     

Simulation study of slow extraction for the Shanghai Advanced Proton Therapy facility

The Shanghai Advanced Proton Therapy facility employs third-integer slow extraction. In order to achieve accurate treatment, high-quality spill is needed. Therefore,parameters that may affect slow extraction should be investigated by simulation. A computer model of the synchrotron operation slow extraction was constructed with MATLAB~. By simulating the motion of the circulating protons, we could quantify the influence of machine and initial beam parameters on properties of the extracted beam, such as ripple, uniformity, stability, on-and off-time of the spill and spill width in the synchrotron.Suitable design parameters including the horizontal tunes,power supply ripple, longitudinal RF cavity voltage, RFKO and the chromaticities were determined.     

我国矿产资源开发利用辐射环境监管探索与进展

介绍了我国铀（钍）矿以外的矿产资源开发利用辐射环境监管工作开展的必要性,调研分析了国际辐射防护委员会、国际原子能机构、欧盟、美国等国际组织与国家关于铀（钍）矿以外的矿产资源开发利用辐射环境监管的实践,介绍了我国矿产资源开发利用辐射环境监督管理的范围和要求.     

重水堆技术优势及发展设想

与作为技术主流的压水堆相比,重水堆因其独特的堆芯设计和运行特点,具有燃料灵活多样、铀资源利用率高、可利用钍资源和回收铀、可大量生产60Co等多种同位素的技术优势。秦山三核正在根据重水堆的比较优势开发重水堆相关技术,目前已经实现60Co生产棒束入堆,并正在联合国内外科研院所研发重水堆回收铀应用和重水堆利用钍资源技术。一旦实现重水堆利用回收铀或重水堆利用钍技术,重水堆运行将不再大量消耗天然铀资源,对后续在其他堆型推广应用,多渠道解决核燃料供应并促进核电产业的科学发展均意义重大。     

AD显像剂11C-PIB合成效率的影响因素

¹¹C-PIB是诊断阿尔茨海默病（AD）的特征靶Aβ斑块的正电子放射性药物,本工作系统研究了以¹¹CH₃-Triflate为甲基化试剂合成¹¹C-PIB合成的影响因素。在国产碳多功能合成仪上, 研究前体量、溶剂、反应温度及体系的pH等对¹¹C-PIB效率的影响,并对合成条件进行优化。结果显示：前体量、溶剂、反应温度及体系的pH均明显影响合成效率。优化后的合成条件为：丙酮为溶剂,前体浓度为5 g/L,反应温度为常温,pH为中性。在此条件下,¹¹C-PIB的合成效率为65.2%±4.7%(n=8,校正效率),产品的放化纯度大于99%,比活度为70.6 GBq/g（18.0 TBq/mmoL）。从¹¹CO₂到¹¹C-PIB的合成时间为30 min, 单次合成的产量为3.7 GBq。以上结果表明,通过优化合成条件,可以稳定、高质量地合成¹¹C-PIB,以满足临床需要。     

美国核电厂GALL报告解读

GALL报告是美国NRC颁布的用于指导审查核电厂执照更新申请的技术文件,它采用表单化形式,从具体的构筑物与部件层面出发,详细记录了材料、环境、老化效应与机理、老化管理大纲间逐一对应的关系。基于文献调研与分析,从开发背景、发展历史、内容框架、应用情况等方面介绍了GALL报告的基本信息,应是我国对该文件的首次全面解读,对我国建立核电厂老化管理大纲及有关核电厂延寿的核安全监管法规具有重要参考价值。