Present and future rare isotope accelerator facilities provide new opportunities to explore the structure of unstable nuclei. We report the measurements of the elastic scattering angular distributions of 21Na and 22Na on the doubly magic 40Ca above the Coulomb barrier energies, using high-purity post-accelerated ISOL beams from Beijing Radioactive Ion Beam Facility (BRIF). Angular distributions were measured with a silicon detector telescope array, and relative cross sections were determined with a CaF2 target on Au backing. The data were well reproduced by optical model calculations with Woods–Saxon and USNP potentials, the latter giving better agreement. These results confirm the stable operation and performance of the BRIF ISOL production and post-acceleration system, demonstrate its capability to provide radioactive beams of useful intensity and purity for future investigations of reaction dynamics and astrophysically relevant processes involving proton-rich nuclei, and simultaneously extend proton-rich elastic scattering studies to heavier systems.

The Beijing Radioactive Ion-beam Facility (BRIF), based on the Isotope Separation On-Line (ISOL) technique, consists of a 100 MeV proton cyclotron as the driving accelerator, a two-stage ISOL system for ion separation, a 13-MV tandem accelerator for post-acceleration, a superconducting linac for further boosting beam energies. It is capable of providing ISOL beams in the energy range from 60 to 300 keV, and post-accelerated beams in the energy range from 3 to 10 MeV/u for nuclei with mass numbers of A < 80. For nuclei with A up to 170, energies are still able to reach 3 MeV/u. This facility offers opportunities to address key questions of current interest in nuclear astrophysics, nuclear structure and reactions of unstable nuclei. In this review we present a comprehensive introduction to the BRIF and the typical experimental instruments installed on it, and then summarize current experimental results on unstable Na and Rb isotopes and future plan for development of the BRIF to improve its performance.

The compact cyclotron CYCIAE-100, developed by the China Institute of Atomic Energy (CIAE), can generate a continuous proton beam with an energy of 100 MeV. To meet the pulsed beam requirements for nuclear data measurements, a beam pulsing system was developed. A chopper was installed in the injection line to convert the continuous beam from the ion source into a pulsed beam with a frequency adjustable from the MHz range to lower frequencies. Two phase selectors were used to limit the beam's phase width, and a dual extraction method was employed to reduce beam overlaps in the extraction region, thus achieving quasi-single-turn extraction. The design and fabrication of the chopper and phase selectors were completed, and experimental tests were conducted. The experimental results demonstrated that the pulse width was successfully compressed to less than 5 ns, ensuring sufficiently high energy resolution and providing the conditions for nuclear data measurement experiments.

Nuclear physics has been expanding rapidly to the limits of nuclear stability due to the increase of available rare isotopes[1].The nuclear binding energies of light loosely bound nuclei near the drip-lines are lower than those of stable isotopes located in the β-stability valley.Light loosely bound nuclei could exhibit exo-tic properties,such as neutron halo,neutron skin and two-proton emission.

Based on the excellent radionuclide properties of 18F, amino acids labeled with radioactive nuclide 18F have shown its unique advantages in brain tumor imaging. A liquid target system with niobium as the target material and 18O(p, n)18F isotope was developed based on the 14 MeV cyclotron of the cyclotron research group of the Department of Nuclear Technology and Application, China Institute of Atomic Energy. In order to solve the problems of complicated structure and poor cooling effect of liquid target system cooled by helium, a liquid target system with direct water cooling is designed. The structure design process and material selection of liquid target are introduced in detail, and the stability of its transport system and control system is tested. The analysis results show that the liquid target system produced by this isotope has good stability. Under the irradiation of 20 μA beam intensity for 2 h, the yield of the product is 1.5 Ci. At present, it has been applied in Peking University, the system has good stability and repeatability, and has been highly praised by users.

In some radioisotope production experiments，100 MeV high-current proton cyclotron is required to extract a single-turn beam to meet the experimental requirements，but at present，there is a serious problem of turn overlap when the beam is extracted，and a beam screening device needs to be designed to improve the quality of the drawn beam. The beam screening device has a frame structure and slit motion system based on the cyclotron，and a control system based on PLC design to control the stepper motor and use the electronic ruler and PID control algorithm to achieve closed-loop control. After many times of operation and debugging，the motion accuracy of the mechanical device is ±0.2 mm，and the beam screening can be realized during the operation of the accelerator，which has reference significance for the design and manufacture of the cyclotron beam screening device.

With the rapid development of nuclear science and technology, medical radioisotopes play an increasingly important role in nuclear medicine, and are widely used in the diagnosis and treatment of cardiovascular and cerebrovascular diseases, tumors and other diseases. Accelerator production of medical radioisotopes has the advantages of flexibility, efficiency, system safety and high nuclide activity, and is one of the important production methods to ensure the safe and stable supply of medical radioisotopes. In 2021, China Atomic Energy Authority together with seven other ministries, jointly released the “Medium - and Long Term Development Plan for Medical Isotopes (2021−2035)”, which clarifies that there are 14 important medical isotopes that China needs to focus on developing before 2035, of which 9 isotopes can be produced by accelerators. This article mainly introduces the production and application overview of accelerators for the 9 important medical isotopes listed in the plan. The 9 important medical isotopes include the imaging nuclides 123I, 124I, 64Cu, 68Ga, 89Zr and the therapeutic nuclides 186Re, 103Pd, 225Ac ,223Ra .Among them,225Ac、68Ge and 223Ra are the focus of isotope production in medium and high energy accelerators, and also are the main development trend of accelerator production radioisotopes. This study provides a comprehensive review of the nuclear properties, applications, reaction cross-sections, yields, and production methods of the diagnostic and therapeutic nuclides mentioned above, providing reference for the production of related nuclides.

Cyclotrons are indispensable scientific equipment and platforms for cutting-edge research and are widely applied in nuclear science and life science, as well as the innovative development of nuclear technology. The difficulties and corresponding key technologies of compact high-intensity proton cyclotron research are fourfold: the insufficient axial focusing force of a compact cyclotron frustrates improvements in beam energy and beam intensity; the smelting capacity of large-scale magnets and modern manufacturing restricts magnetic field accuracy, which affects the dynamic performance of high-intensity beams; high-beam dynamic loads and coupling resonance considerably influence the stable operation of cyclotrons; and high-intensity negative hydrogen ion sources, the coupling of multiple physical fields in the narrow space of the central region, and the high-precision six-dimensional matching of beam optics in the extraction region are also great challenges for compact high-intensity cyclotrons. To solve these problems, a strong focusing theory of radially modulated magnetic field gradients was innovatively created by a cyclotron team at the China Institute of Atomic Energy (CIAE), and a parallel computing algorithm and software for multi-cluster high-intensity beam dynamics were also invented. These innovations extend the acceleration energy limit of compact cyclotrons and help increase beam intensity substantially under the restriction of space charges. A magnet shimming algorithm for isochronous fields and nonideal harmonic fields, based on the shape function of odd and even triangles, was developed to improve axial focusing effectively and solve problems in magnet engineering. Key RF technologies, such as suppression of "transmission line-resonator" system coupling oscillation and dynamic loading changes, were researched, and then a long-term operation with high stability was achieved for the entire machine. A high-intensity cyclotron prototype with strong focusing was built based on these innovations, effectively promoting the beam intensity of miniaturized cyclotrons from 50-100 mu A to 300-500 mu A. Subsequently, more than ten high-intensity compact cyclotrons have been developed at the CIAE, and these cyclotrons can provide beam intensity at the mA order after necessary upgrades. The main performance indexes of the cyclotrons, such as intensity, injection efficiency, and extraction efficiency, are world-class. Cyclotron applications are also applied in the projects of the CIAE, National Space Science Center, Irradiation Hardening Application Technology Innovation Center, and Peking University and contribute much to scientific research. We provide proton beams for similar to 100 units to perform scientific and technological research related to nuclear technology and its applications. The research and applications prompt the development of high-intensity proton cyclotrons.

ABSTRACT A new double-gap buncher is designed for the CYCIAE-10 cyclotron in order to get the high-intensity proton beam with the order of mA. RF simulation is carefully performed to achieve a deep quantitative analysis of the equivalent capacitance and electrical field distribution. Uniform electrical field technology is verified by EM field simulation to get an electrical field uniformity of 94.67%. Type L matching circuit is used to transfer the loading reactance to 50 Ohms. Variable vacuum capacitor with 5–50 pF is selected for its small power loss and the convenience of commissioning. Dynamic calculation of the buncher and mechanical design are also presented in this paper. The open-loop bench test shows that 370 Vpeak RF voltage is established in the central electrode with power consumption of 37 W. Alternative redesign and online test are carried out, and more than 1 mA H− beams are achieved on the inner target, which verify the buncher design. Graphical Abstract

通过理论分析和仿真模拟对中国原子能科学研究院一台100 M eV强流质子回旋加速器的束流切割器进行了优化设计,并同时研制出两套束流切割器进行实测对比,选定最佳方案.该切割器波形选择为回旋加速器高频频率的16分频2.8 M Hz正弦波,具有结构紧凑体积小、螺旋谐振器Q相对较高、加载切割电压较高且功率损耗低、无需水冷等特点,同时配套研制了一套开口形状为正方形的选束狭缝装置.最后在实验终端成功获得了能量为100 M eV、重复频率为5.6 M Hz的脉冲质子束.该切束器的成功研制不仅满足了核数据测量的应用需求,还极大地推动了回旋加速器束流脉冲化技术的发展.

Superconducting synchrocyclotron for proton therapy has grown rapidly in recent years. Frequency modulation is considered as the unique technology of synchrocyclotron. In the process of theoretical cavity design of CIAE-230 MeV superconducting synchrocyclotron, the frequency modulation algorithm, based on the characteristic of cavity electromagnetic field distribution, is developed and then validated on the model cavity test. The rotor system works effectively at the speed of 7500 RPM, which indicates that the cavity modulation frequency reaches the kHz level. The interactive design related to the magnetic field is also introduced in this paper. The technical feasibility research on frequency modulation in this paper paves the way for the whole machine development.

Yttrium-86 (86Y, t1/2 = 14.7 h, 33% β+) is a nonstandard medical nuclide with a longer half-life than other standard nuclides such as gallium-68 for radiolabelling for PET (positron emission computed tomography) imaging. 86Y is compatible with DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and can be used to evaluate DOTA-chelated radiopharmaceuticals with long clearance half-lives, particularly therapeutic radiopharmaceuticals in several days. 86Y can be produced through 86Sr(p, n)86Y reaction, in which 86Sr-enriched SrCO3 powder is bombarded with low-energy protons. To handle the SrCO3 powder, a powder target for 86Y production in 14.6 MeV proton cyclotron was designed while maximizing yield, reliability and efficiency. To that end, the target's primary design parameters were traversed, simulated and optimized using computer algorithms to obtain advantageous parameter combinations. In this way, 86Y was produced on the powder target with high yield and successfully isolated with high purity (>97%) by solid-phase extraction via DGA resin for high-quality PET imaging and drug screening.

In this paper, the domestic and international demand and development trend of clinical diagnostic radionuclides are analyzed, and the medium and high-energy cyclotrons, adequate and systematic facilities, and preparation techniques required for the production of medical radionuclides based on solid targets are introduced. This paper focuses on the research and development carried out by some important medical institutions and scientific research institutes in China over the years in the aspects of medium and high-energy cyclotrons, beam transmission lines, high-power irradiation target stations and new medical isotope production processes etc. It also looks forward to some new directions for the development of medical radionuclides in China during the 14th Five-Year Plan period.

在230 MeV超导回旋加速器中,磁场调节棒及其驱动系统是束流调试的重要辅助装置.为满足束流对中和束流引出所需的磁场,设计并研制了16套磁场调节棒及其驱动装置.机械执行机构采用美国Thomson公司的精密直线执行器,其重复定位精度为±0.01 mm,位置传感器采用德国Novotechnik公司的直线位移电子尺,其重复精度为0.002 mm.此外,运动控制采用PLC加直线位移传感器负反馈闭环的方案.在实际工况下,系统定位精度达到0.05 mm,重复精度达到±0.02 mm,优于设计要求.此外,对该系统进行了静电放电测试、电快速瞬变脉冲群测试和浪涌抗扰度测试,结果满足医用电气设备电磁兼容标准YY 0505-2012/IEC 60601-1-2:2004的要求.该驱动系统的研制,克服了在强电离辐射、高磁场强度、狭小安装空间的特殊环境中达到高定位精度和高重复精度的难点,对优化束流的径向进动、减小加速区域的相干振荡振幅、提高引出区的束流引出效率等具有重要意义.

中国原子能科学研究院目前正在研制用于硼中子俘获治疗(BNCT)的强流质子回旋加速器,该加速器设计引出能量14 MeV、质子束流强大于1 mA.相比引出流强为400μA的PET回旋加速器,BNCT强流质子回旋加速器对中心区相位接收度和轴向聚焦的要求更高.为实现mA量级的束流的加速和引出,BNCT强流质子回旋加速器采取了增加负氢束流注入能量、增大磁铁镶条孔径、使用用于增大D ee盒头部张角的阶梯状结构及调整加速间隙的入口和出口高度等一系列中心区结构优化设计,有效地提高了中心区的相位接收度,改善了轴向电聚焦.在新的离子源注入能量下通过数值计算得到实测场下的轴向电聚焦和间隙高度的关系,选取合适的间隙高度获得最佳的轴向聚焦,从而确定了mA量级束流的注入和加速的中心区结构.同时在设计中考虑空间电荷效应的影响,计算了不同流强下的束流尺寸变化.中心区结构在实测磁场下的优化设计计算结果表明,BNCT强流质子回旋加速器中心区的束流对中好于0.5 mm,相位接收度大于40°,中心区最高可接收流强3 mA.目前,新的中心区结构已进入机械加工阶段.

中国原子能科学研究院建成了100 MeV紧凑型强流质子回旋加速器,其引出能量为75～100 MeV,流强为200～500μA.为了减小粒子加速时束流损失并满足加速器粒子对真空的要求,文中设计了一个内径为4040 mm、高度为1270 mm的主真空室来保证加速器的真空.介绍了主真空室结构设计的难点,并对应力分析情况、放射性防护方面设计进行了介绍.

A 14 MeV high intensity compact cyclotron, CYCIAE-14, was built at China Institute of Atomic Energy (CIAE). In order to provide high quality proton beams for instant radiopharrnaceutical distribution, and to produce a variety of radioactive ion beams taking use of the solid target, CYCIAE-14 adopts an injection system based on the external H+ ion source, axial injection, and spiral inflector with a designed high beam intensity, while most PET cyclotrons adopt internal ion source. With the different using for the cyclotron, there are two projects. One project with 200 mu A/14 MeV can be used for isotope production of C-11, O-18, N-13 and F-18. Another project with more than 400 mu A with 14 MeV can be used for more isotopes produced such as Cu-64, I-124 and Tc-99m. This paper will introduce the cyclotron of CYCIAE-14 with the two projects, and some experiments finished on the cyclotron will also be given in the paper, for example the F-18 and Zr-89 production, BNCT test.

为调试100 MeV回旋加速器高功率束流及放射性同位素研制,设计了一条高功率质子束流线及可插拔式高功率束流调试靶.研究了100 MeV回旋加速器引出区色散效应及剥离膜的散射效应,从而优化了光学模拟的初始参数,使得模拟结果更加精确.高功率束流调试靶设计为可插拔式以代替常用固定式调试靶,该靶插入束流管道中时可进行高功率质子束流调试,在拔出时,质子束流可直接轰击束流线终端的靶站以生产放射性同位素.优化了高功率束流调试靶的水冷结构,确保调试靶可承受500μA以上的质子束流.经调试,该束流线可传输最高流强520μA的质子束流.

CYCIAE-100, a 100 MeV high current compact cyclotron has been constructed and first beams were extracted in 2014. The machine has 5 beam lines for multi-application purposes. N1, one of the beam lines, is designed for high current beam transportation, for beam dump tests and isotope production. In 2016, a mA proton beam was tested on the internal target. In 2017 and 2018, 200 mu A and 520 mu A proton beams were extracted and transported to the beam dump respectively. In addition to increasing the cw beam power of 52 kW extracted from the machine and transported to the beam dump, this paper will also present the simultaneous dual-beam extraction from CYCIAE-100 and the improvement of the uniformity of the beam spot on the target, which will benefit isotope production.