辐射场监测在合肥光源中的应用研究

合肥光源于近期完成了重大升级改造,对电子加速器和储存环的结构进行了重新调整,同时升级了辐射监测系统和束流损失监测系统。除了具备基本的机器保护与人员安全防护功能以外,通过加入时间信息、位置信息和加速器运行参数信息,新监测系统还具有一定的机器诊断能力,对加速器的调机和维护有辅助作用,同时也加深了对辐射源项的了解,对优化防护措施有指导意义。     

托卡马克实验装置的实验大厅移动辐射监测机器人设计

托卡马克实验装置(experimental advanced superconducting tokamak, EAST)在进行聚变等离子体放电实验时,随着中性束注入、低杂波电流驱动、电子回旋波共振加热等大功率辅助加热系统投入运行,等离子体中子出射强度可达10¹⁴ n/s,这导致大厅及窗口区域的中子光子剂量率明显增加。为了保证工作人员及维护人员的安全,需要及时了解不同位置处的辐射剂量。本研究基于六轮移动救援机器人底盘,研制EAST实验大厅移动辐射监测机器人,并搭载X、γ辐射在线监测仪,通过同步定位与建图技术（SLAM）构建环境地图自主移动或通过高清图像远程控制及数据传输系统,将大厅内不同位置的辐射剂量值传递给上位机。通过巡测路径上的剂量率异常,可向周围的工作人员及时发出警示,以此确保实验人员的辐射安全和判断现场维护人员的滞留时间。     

The NRL Cyclotron Beam Control and Handling System

The beam handling apparatus and its associated remote control arrangements are described for the NRL Cyclotron Beam Transport System. The need for reducing duplication of controls and power supplies for such a multi-beam-path facility resulted in the development of a rapid master selector system which can be programmed to accommodate the different beam path requirements. All ion optics and beam sensing components along any particular beam path can be activated from a single selector panel, and then individually controlled. The beam transport display, vacuum control display, and control console, are laid out in graphic form wherever feasible in an effort to present readout and control information concisely and continuously. Precision, versatility, modular construction, and ease of maintenance guided the mechanical and electrical design criteria. Design details and prototypes of beam stops, scanners, viewers, collimators, probes, and pumping stations, are discussed.     

A real-time beam loss monitoring system for storage ring of SSRF

In this paper we report the real-time beam loss monitoring (BLM) system at the storage ring of SSRF.The BLM-XS detectors and Ethernet data acquisition system are used in this system.Some applications and experiments of the BLM system are also presented.The BLM system provides dynamic information of beam loss for the storage ring,and is helpful to ensure the facility commissioning,investigate the problems of machine,optimize the machine parameters and further increase the beam lifetime.     

Collection, cooling and delivery of ISOL beams

The collection of an ISOL beam in a Penning trap using implantation on a surface that is subsequently manipulated so as to become part of an end electrode of a Penning trap and reionization of the implanted material by heat has already been very productive for high-precision nuclear-mass measurements, even though it is limited to elements that are surface ionizable and the collection efficiencies are never better than about 0.1%. More recently, in 1990 a Paul trap system for electric collection of ions was installed at the ISOLDE-3 facility and collection was demonstrated for a 60 kV beam of ¹³²Xe ions. The purpose of this test setup was to determine the relationship between phase space volume of a typical trap and the collection efficiency that could be obtained in direct capture. For the modest trap used, collection efficiencies of up to 0.2% were achieved. A beam of negative bromine ions was collected by simply reversing the polarities of all voltages used. From the experience with this system it appears feasible to build a Paul trap which is about three times as large in linear dimensions as the existing one and which could be driven at up to 10 kV peak at 1 MHz using a modest rf amplifier (300 W). With moderate prebunching of the injected beam at 1 MHz, this system should achieve collection efficiencies approaching 100%. Based on these results, preliminary design work is being carried out on the collection system to be installed at the ISOLDE Booster facility. Suggestions for other uses of a Paul trap collection system for ISOL beams are presented.     

The new CERN-ISOLDE on-line mass-separator facility at the PS-Booster

The ISOLDE on-line isotope separators have been operated since 1967 at the CERN-SC. This 600 MeV proton synchro-cyclotron had to be shut down in December 1990 after 33 years of service and it was decided to move ISOLDE to a new experimental area. The new on-line mass-separator facility is now under construction at the CERN PS-Booster. This accelerator provides an average current of about 2 μA of 1 GeV protons in very short high intensity pulses at low repetition rate. The beam can hit either one of the two target stations, the general purpose separator (GPS), a reconstructed ISOLDE-2 type machine (which can deliver beams simultaneously into three beam lines), and the high resolution separator (HRS), which is essentially the slightly modified ISOLDE-3 separator. The central GPS beam line and the HRS feed a common beam transport system to which most of the experiments will be connected. The new facility will be taken into operation in spring 1992.     

Optimization of a neutron detector for pulsed photonuclear monitoring of fissile materials

The objective of the present work is optimization of the geometry of a multilayer detector used in the pulsed photonuclear method of remote monitoring of fissile materials. Numerical simulation of the conversion of an electron beam into bremsstrahlung and the interaction of the latter radiation with components of the facility and the contents of the object of monitoring, resulting in neutron emission, is performed. The spectral-time parameters of the neutron flux arriving at the detector are obtained and the probability of detecting neutrons with different energy is calculated as a function of the thickness of the layers for moderation and absorption. The construction of the detector giving high fission-neutron detection efficiency and low sensitivity to background neutrons is chosen. The data obtained were used to build the neutron detector used in the experimental model of a facility for detecting fuel-cycle materials by the photonuclear method based on the U-28 accelerator. Translated from Atomnaya énergiya, Vol. 106, No. 1, pp. 48–52, January, 2009.     

A variable-energy positron beam for low to medium energy research

A positron beam facility is described which provides a monoenergetic beam (± 1 eV) which is variable in energy from a few eV up to a maximum of ∼ 80 keV. The positron moderation process, beam transport, and design of the target chamber are discussed in detail. Some of the research being done with the facility is summarized, including scattering and energy-loss measurements, near-surface defect profiling studies, and low energy positron channeling studies. An ultrahigh-vacuum 2-axis goniometer is described, which is used in the channeling work.     

High Sensitivity Measurement of Iodine-129/Iodine-127 Ratio by Accelerator Mass Spectrometry

An iodine beam line has been set up at the AMS facility of the Japan Atomic Energy Agency. This beam line has a high mass resolution magnet and a high energy resolution electrostatic analyzer to remove the interfering peaks. Reproducibility of 0.53% and precision of 1.1% attained after solving some problems and realigning the equipments again are better than those of the acceptance test. It was demonstrated that this beam line has excellent measurement linearity between 10^?10 and 10^?12 iodine isotopic ratio by testing standard samples which have a variety of iodine isotopic ratios. Its detection limit is substantially below 10^?13 iodine isotopic ratio. Evaluating these performance tests, it was found that this iodine line would be a potentially powerful tool not only for monitoring around a nuclear facility but also for geochemical studies such as dating and tracing in hydrogeologic and oceanographic research.     

Laboratory and In-Beam Tests of a Novel Real-Time Beam Monitor for Hadrontherapy

Real time monitoring of hadrontherapy beam intensity and profile is a critical issue for the optimization of dose delivery to carcinogenic tissue, patient safety and operation of the accelerator complex. For this purpose an innovative beam monitor, secondary electron emission for low interception monitoring (SLIM) is being developed in the framework of the EC-funded silicon ultra-fast cameras for electrons and gamma sources in medical application (SUCIMA) project. The detector system is based on the secondary emission of electrons by a nonperturbative, sub-micron thick Al foil placed directly in the extracted beam path. The secondary electrons, accelerated by an electrostatic focusing system, are detected by a monolithic silicon position-sensitive sensor, which provides the beam intensity and its position with a precision of 1 mm at a 10 kHz frame rate. The results of the laboratory tests of the first system prototype with thermoionic electrons emitted from a hot Tungsten wire are presented together with the measurements performed on a low intensity hadron beam at the Cyclotron of the Joint Research Centre in Ispra.     

上海硬X射线自由电子激光装置调试用束流收集桶的设计

在建上海硬X射线自由电子激光装置(Shanghai high repetition rate XFEL and extreme light facility,SHINE)包含一台8 GeV的超导直线加速器,100 PW的激光系统,三条波荡线和10条实验线站。主加速器的第三磁压缩段(BC3段)有一调试用的束流收集桶,BC3段的调试电子流强为0.3 μA、能量为7.7 GeV,束流功率为2.31 kW。本文从材料对7.7 GeV电子的能量吸收方面考虑,对束流收集桶的结构进行了确定。用ANSYS 17.0对束流收集桶的温度场进行了分析,结果证明在有表面空气自然对流换热的情况下,铝芯的最高温度为193.14 ℃,在束流收集桶坑道无外界换气的情况下,束流收集桶需要外围冷却水;用蒙特卡罗程序FLUKA对束流收集桶的活化进行了分析,保守假设束流收集桶连续注束2 000 h。结果证明要保证停机1 h后,束流收集桶周围30 cm处的剩余辐射剂量小于25 μSv/h,束流收集桶外围需要55～85 cm的混凝土屏蔽体;结果显示束流收集桶的剩余辐射剂量在30 min内衰减的非常快,这是由于刚停机时束流收集桶内产生的50%左右的放射性核素半衰期都小于10 min。     

Monitoring the Electron-Orbit Shift and Radiation Beams

A system for performing television monitoring of the position of the synchrotron radiation beam is discussed. The results of measurements of the stability of the beam position in several user channels are presented. It is shown that further work is needed to determine and eliminate the factors causing beam displacement. The results of measurements performed by different methods of the electron-beam dimensions in the accumulator are presented.     

重离子束治癌装置及技术发展

首先简要回顾了重离子束治癌在我国的兴起与发展的情况.随后着重介绍了重离子束治癌装置及部分关键技术:总体布局方案、束流引出模式、束流配送系统、束流旋转机架、辐照门控系统、PET成像等.     

New directions in the Bartol PIXE system for studies in archaeometry

This paper describes, firstly, the physical processes of PIXE that underly its advantages as an analytical tool and the practical limitation met in the compositional patterning of ancient bronzes, irons and glasses. Controlled variation of the energy of the proton beam and the use of selective filters in the X-ray detection system allows certain background effects from the X-ray output of the dominant elements to be significantly reduced. Secondly, plans for a new beam line for the Bartol PIXE facility are described. This system will provide for a beam diameter as small as 20 μm with a laser-based optical system that will allow for the precise location of the proton beam on the artifact's surface. This system will enable one to study inhomogeneous materials, such as metal residues trapped in smelted slag, solder joints in classical jewelry and islands of metal in heavily corroded artifacts.     

IR-FEL装置数据存档和查询系统

IR-FEL装置控制系统是基于EPICS的分布式控制系统,装置运行过程中产生的历史数据可用于装置的性能分析和故障诊断,对装置的性能提升和运行维护具有重要意义。本文以Archiver Appliance作为历史数据存档工具,采用前、后端分离的软件架构,设计和开发了IR-FEL装置数据存档和查询系统。系统后端包含历史数据查询和实时数据推送两种服务端程序,使用Nginx反向代理服务器提供了统一的数据查询接口;前端是基于Vue.js的单页应用,提供了历史数据定制查询、自由查询和运行状态显示页面。系统自投入运行以来,性能稳定、功能完善,满足了IR-FEL调试和运行的需求。     

Advances in neutronics and radiological protection of HiPER 4a

The HiPER project, phase 4a, is evolving. In this study we present the progress made in the field of neutronics and radiological protection for an integrated design of the facility. In the current model, we take into account the optical systems inside the target bay, as well as the remote handling requirements and related infrastructure, together with different shields. The last reference irradiation scenario, consisting of 20 MJ of neutron yields, 5 yields per burst, one burst every week and 30 years of expected lifetime is considered for this study. We have performed a characterization of the dose rates behavior in the facility, both during operation and between bursts. The dose rates are computed for workers, regarding to maintenance and handling, and also for optical systems, regarding to damage. Furthermore, we have performed a waste management assessment of all the components inside the target bay. Results indicate that remote maintenance is mandatory in some areas. The small beam penetrations in the shields are responsible for some high doses in some specific locations. With regards to optics, the residual doses are as high as prompt doses. It is found that the whole target bay may be fully managed as a waste in 30 years by recycling and/or clearance, with no need for burial.     

The Utrecht accelerator facility for precision dating with radionuclides

The Utrecht facility for accelerator mass spectrometry is described. The set-up with an EN tandem accelerator is designed for measurements of a broad range of long-lived radionuclides and of stable trace elements. In particular, dating measurements with ¹⁰Be and ¹⁴C can be performed with high precision by rapid switching between the measurements of the isotopes. Optimal beam transmission through the accelerator is achieved with a new injection system in conjunction with the installation of axially symmetric acceleration tubes with spirally inclined electrodes. The first ¹⁴C/¹²C measurement with this set-up is reported.     

Charge integration in external-beam PIXE

Direct measurements of the beam current in external-beam PIXE are difficult due to the ionization of air molecules. A method for indirect charge integration has been earlier presented by our research group. The method utilizes the light emission from air molecules excited by the particle beam. The light emission originates from the second positive band system in N₂. The light was measured with a photomultiplier tube. The geometry and the electronics have been improved during the six years that have passed since the method was taken into use. The current from the PM-tube is today about 210 times higher than the particle beam current measured by the means of a Faraday cup. This amplification is useful in the monitoring of small beam currents. The linearity and accuracy of the improved system are discussed.     

Design study of a rotating gantry for the HIMAC new treatment facility

A project to construct a new treatment facility as an extension of the existing HIMAC facility has been initiated for the further development of carbon-ion therapy. In the new facility, one of the treatment rooms will be equipped with an iso-centric gantry system employing a 3D pencil beam scanning irradiation method. In order to realize a compact design, the final 90° bending magnet is divided into two bending magnets of 60° and 30°. The scanning magnets are set between these two bending magnets, although the aperture of the 30° magnet increases. Finally, we achieved 350 tons of total weight for 400 MeV/u carbon beams with a 150 mm square field.     

Therapeutic techniques applied in the heavy-ion therapy at IMP

Superficially-placed tumors have been treated with carbon ions at the Institute of Modern Physics (IMP), Chinese Academy of Sciences (CAS), since November 2006. Up to now, 103 patients have been irradiated in the therapy terminal of the heavy ion research facility in Lanzhou (HIRFL) at IMP, where carbon-ion beams with energies up to 100 MeV/u can be supplied and a passive beam delivery system has been developed and commissioned. A number of therapeutic and clinical experiences concerning heavy-ion therapy have been acquired at IMP. To extend the heavy-ion therapy project to deep-seated tumor treatment, a horizontal beam line dedicated to this has been constructed in the cooling storage ring (CSR), which is a synchrotron connected to the HIRFL as an injector, and is now in operation. Therapeutic high-energy carbon-ion beams, extracted from the HIRFL-CSR through slow extraction techniques, have been supplied in the deep-seated tumor therapy terminal. After the beam delivery, shaping and monitoring devices installed in the therapy terminal at HIRFL-CSR were validated through therapeutic beam tests, deep-seated tumor treatment with high-energy carbon ions started in March 2009. The therapeutic techniques in terms of beam delivery system, conformal irradiation method and treatment planning used at IMP are introduced in this paper.