HIAF-BRing中极化质子加速研究

为了更深入地研究核子性质,中国科学院近代物理研究所将在强流重离子加速器装置（HIAF）上利用极化质子束开展实验。HIAF增强器BRing能够提供最大能量9.3 GeV/u的极化质子束,在加速过程中极化束流会遇到多次退极化共振,需要特殊设计才能使束流保持较高的极化度。利用退极化共振强度模拟程序DEPOL,研究了BRing加速过程中不同退极化共振对束流极化度的影响。结果表明,加速过程遇到的两种退极化共振将会使束流完全退极化;在BRing电子冷却段加入Full Siberian Snake可以使质子束在加速时保持较高的极化度。In order to explore the nucleon properties in details, the polarized proton will be used for some special experiments at HIAF project in Institute of Modern Physics, Chinese Academy of Sciences (IMP,CAS). The maximum energy of 9.3 GeV/u for Polarized protons will be provided in the Booster Ring(BRing) at HIAF. The polarized beam experiences depolarizing resonances many times during acceleration process, so it's necessary to suppress those resonances to keep polarizability well by special design. In this paper, the code DEPOL is used to simulate the influence of depolarizing resonances process in BRing. According to the results, the beam's polarization has been destroyed completely by the depolarizing resonances in the acceleration process. And the Full Siberian Snake is chosen in the Electron Cooler part of BRing to preserve the beam's polarization during the acceleration, and its strength and location of the Siberian Snake are also presented here.     

BRing中电荷交换引起的束流损失分布模拟计算

在强流重离子加速器运行中,带电粒子与真空管道中的残余气体分子相互作用发生的电荷交换反应是影响重离子束流寿命的关键因素。这种电荷交换过程导致的束流损失将解吸出真空管壁上吸附的气体分子,进而引起真空压力的动态变化,将严重影响加速器的稳定运行和最终束流引出流强。中国科学院近代物理研究所将在广东省惠州市建造的强流重离子加速器装置（High Intensity heavy-ion AcceleratorFacility,简称HIAF）利用增强器（Booster Ring,简称BRing）提供束流流强高达2×1011 ppp的238U35+用于核物理及原子物理等实验研究。对强流重离子加速器BRing中238U35+束流发生电荷交换反应,损失一个电子成为238U36+的过程进行了追踪模拟,计算得到了U36+损失前的运动径迹和全环粒子损失位置分布,模拟结果显示U36+受到色散元件的影响,将集中损失在位于二极磁铁后的漂移节区域中。基于模拟结果,在束流损失位置处设计安装由低解吸率材料制作的准直器,优化设计后的准直效率高达95%以上;并模拟计算了有无准直器时真空压力和束流流强的变化,安装准直器后BRing的平均真空度变化小于10%,将确保BRing加速器的稳定运行。During heavy ion accelerator operation, the charge exchange effect between ions and residual gas molecules is the key factor to influence beam lifetime. The charge exchange process has ions lost on the wall and leads to a dynamical vacuum change, which will seriously affect the accelerator operation and reduce the extraction beam intensity. The Institute of Modern Physics' future project, called High Intensity heavy ion Accelerator Facility (HIAF), will be built in Huizhou city, Guangdong Province, China. The Booster Ring (BRing) will provide 2×11 ppp 238U35+ for nuclear physics experiments. This article studies the track of particle U36+ before impacting on the wall, which is the reference particle U35+ losing one electron, and gets the U36+ loss distribution along the BRing. The simulation result shows that U36+ will be influenced seriously by dispersion elements, and will be lost in the drift sections after the dipoles. Collimators made out of materials with low desorption will be installed in the particles lost positions. The collimator efficiency after optimization can be larger than 95%. It also shows BRing average pressure change and beam intensity change between collimators on and off. The result points out that the BRing average pressure change will be less than 10% with collimators on, which makes BRing operate stably.     

HIAF BRing及高能外靶实验终端的辐射屏蔽设计

强流重离子加速器（HIAF）是中国科学院近代物理研究所自主研制的一台高能强流重离子加速器,它可以实现p到U的全离子加速。为了保证HIAF运行时的辐射安全,针对该装置的增强器（BRing）及高能外靶实验终端,利用蒙特卡洛程序FLUKA及外推法计算得到了加速p,C及U三种离子时所需的辐射屏蔽。结果表明,加速质子时所需屏蔽厚度最大,并以此为依据给出了全地下结构的屏蔽设计。在此基础上,提出了一种估算高能质子/重离子加速器束流均匀损失时横向屏蔽厚度的方法。结果显示,估算结果与FLUKA计算结果符合较好,验证了该方法的有效性和准确性。High Intensity heavy-ion Accelerator Facility (HIAF) is designed by the Institute of Modern Physics, Chinese Academy of Sciences, which can accelerate particles from proton up to uranium. To guarantee the radiation safety of HIAF during operation, the FLUKA code and extrapolation method were adopted to calculate the shielding thickness. The calculations were based on proton, carbon and uranium particles when losing on the Booster Ring (BRing) and the high-energy experimental terminal. The results indicate that the shielding thickness required for accelerating protons was the largest. Basing on the results, a method for estimating the lateral shielding of a high-energy proton/heavy-ion accelerator was proposed. A good agreement shows between the estimated results and the FLUKA calculated results, the validity and accuracy of the method were verified.     

HIAF-SRing的等时性模式光学设计

高精度环形谱仪SRing作为HIAF装置的核心之一,是获取高品质放射性次级束,并将束流用于加速器技术研究、原子物理及核物理实验的关键设备。SRing有三种运行模式:等时性模式、正常模式与内靶模式。等时性模式下,SRing运行在特殊线性光学设置下,可以精确测量寿命低至几十微秒的原子核的质量。介绍SRing等时性模式的线性光学及高阶项校正的设计方案。在使用程序GICOSY进行等时性高阶项校正数值计算后,将得到的光学传输矩阵输入到程序MOCADI进行粒子跟踪模拟。以γ_t=1.43的等时性模式为例,SRing的动量接收度为±0.20%,粒子跟踪结果显示,在仅满足一阶等时性条件时SRing的质量分辨能力R=1.6×104。在保证动量接收度不变的前提下,考虑了等时性高阶项校正后SRing的质量分辨能力提高到R=1.2×106,达到设计要求。The Spectrometer Ring, as the most important experiment terminal of the High Intensity heavy-ion Accelerator Facility (HIAF) project, is a key device to obtain high-quality radioactive ion beams (RIBs) for atomic physics, nuclear physics experiments and accelerator technology researches. Three operation modes including the isochronous mode, the normal mode and the internal target mode, have been designed for the SRing. In the isochronous mode, the SRing operates under a special ion optics and could be used for precision mass measurement of short-lived nuclei with half-life shorter than several tens of microseconds. This study aims to design the ion optics for the isochronous mode and improve the mass resolving power of the SRing with higher-order ion-optical correction scheme for isochronism while preserve a large momentum acceptance of SRing. The ion optics and the higher-order correction for the isochronous mode are calculated with the code MAD-X and GICOSY respectively. Three ion optics with γ_t=1.43, 1.67, 1.83 settings have been calculated. The code MCOADI which utilizes the matrixes generated by the code GICOSY is used for particles tracking to verify the correction results. For the ion-optical setting of γ_t=1.43 with a momentum acceptance of ±0.20%, the mass resolving power of the SRing could be improved from R=1.6×104 to R=1.2×106, after isochronous higher-order corrections.     

储存环HIAF-SRing等时性模式的非线性磁场影响研究

高精度环形谱仪SRing（Spectrometer Ring）是强流重离子加速器装置（HIAF）的重要组成部分,其等时性模式为远离β稳定线的短寿命原子核质量和寿命的精确测量提供国际领先的科研条件。为了扩大短寿命原子核质量测量精度和范围,SRing等时性模式设计了两种光学:γ_t=1.43和1.67。质量分辨是衡量等时性储存环的最重要参数。二极磁铁的高阶场以及磁铁的边缘场能强烈地引起束流光学高阶畸变,对质量分辨产生影响,因此需要高极磁铁对其进行校正。介绍了SRing等时性模式的线性计算,对非线性磁场的影响进行了详细研究。应用六极磁铁和八极磁铁对非线性场和发射度的影响进行了校正后,离子的循环时间标准偏差σ（T）/T达到3.5×10-7,质量分辨△m/m达到1×106。The isochronous mode of the Spectrometer Ring at the High Intensity heavy-ion Accelerator Facility (HIAF) project in China offers the capacity of measuring the mass and half-life of short-lived nuclides. The transition energy settings of the SRing are 1.43 and 1.67, which have been calculated in the same injection scheme. The resolution of mass or revolution time is the most important parameter of the isochronous mode design of a storage ring. The nonlinear magnetic field errors, including high-order magnet field of dipole, fringe field of magnets, have strongly effect to the resolution of revolution time. High-order corrections are required to improve the resolution of revolution time and mass. In this paper, the SRing linear isochronous optical were shown. The influence of nonlinear magnetic field errors on the revolution time resolving power were investigated. With 3 sextupole families and 1 octupole family corrections, the relative variation of revolution time reaches 4.6×10-7 with the momentum spread of ±0.2%. The relation of the relative standard revolution time deviation σ(T)/T and revolution turns was researched. With corrections of high-order isochronous condition and emittance influence by 3 sextupole families and 1 octupole family, one can reach a resolution of up to σ(T)/T=3.5×10-7, which corresponds to the mass resolution of △m/m=1×106.     

HIAF-BRing的双向涂抹注入模拟

BRing是HIAF工程的主加速器,其设计流强为每个脉冲内的粒子数1×1011个（238U34+）,为了达到此设计流强,注入增益应达到88倍以上。BRing采用了双向涂抹注入方案,其满足BRing的注入增益要求,同时具有注入时间短和累计束分布较均匀而减小了空间电荷效应的特点。双向涂抹注入方案利用水平和垂直两组凸轨磁铁以及倾斜的静电偏转板,在水平相空间和垂直相空间内同时进行涂抹。为了检验双向涂抹注入方案能否达到BRing的设计要求,利用ORBIT程序对双向涂抹注入过程进行了模拟,模拟结果显示,在单次双向涂抹注入113圈的情况下,注入效率为97.7%,注入增益达到110.3倍,满足了BRing流强要求。累积束的分布相对均匀,空间电荷效应引起的工作点漂移约为-0.02,粒子因共振损失风险很小。针对注入束流偏角、切割板角度、工作点偏差和Bump延时等不同注入参数进行了误差分析,结果显示BRing的双向涂抹注入效率对注入参数偏差的容忍度较高。BRing is the main accelerator of High Intensity heavy Ion Accelerator Facility(HIAF) and its design current is 1×1011 particles per pulse (238U34+). To accumulate beams up to the design current, the injection gain has to reach 88. Two planes painting injection scheme is proposed for BRing. This scheme uses a tilted electrostatic septum and 8 bump magnets to paint beams into horizontal and vertical phase space simultaneously. It can inject enough beams into the ring in a short time and paint beams uniformly. The injection process is simulated using ORBIT code and 113 turns is injected into BRing with an injection efficiency of 97.7% which meets the requirement for beam current of BRing. The accumulated beams are distributed uniformly in transverse and hence have a little tune shift of -0.02 which reduces the risk of beam loss due to the resonance. Errors of injection parameters are analysed and the result shows two planes painting injection scheme has a high tolerance for errors of injection parameters.     

Progress of HIRFL-CSR Project in 2003

Great progress was achieved in HIRFL-CSR project in the year of 2003. A large number of components has been completed, tested, installed, and commissioned, especially for the HIRFL-upgrade, for the new injection beam line to the CSRm and for the CSRm. The project is now in the transition from the construction to the installation and commissioning phase. Component delivery and installation is proceeding in accordance with schedule. On the average more than 98% of the components have been contracted. More than 350 magnets have been manufactured. The magnets, the power supplies, the vacuum system and the beam detectors for the injection beam line to the CSRm have been installed. All the magnets for the CSRm have been manufactured     

The parametric source method for measuring characteristics of underwater acoustic materials in a pressure vessel

A truncated broadband parametric array with a primary frequency of 500 kHz and difference frequency range of 1 kHz to 30 kHz was designed as a sound source of the underwater acoustic material measurement system.By analyzing the theoretical calculation and actual measurement results in array directivity of the truncated broadband parametric source at typical frequencies,we observed that the curves of the two results were basically consistent,which proved that the calculation model was correct.Application of bell-shaped short-duration pulse to achieve broadband measurement for characteristics of underwater acoustic materials was beneficial to reduce the effects of diffraction from the panel edges.The measurement system was established for measuring the sound pressure reflection coefficients,sound pressure transmission coefficients and absorption coefficients of the large panel sample in the pressure vessel.The size of this tank is φ4 m×12 m,the maximum hydrostatic pressure is 4.5 MPa,and the corresponding measuring frequency range is from 1 kHz to 30 kHz.The measured curves had a good agreement with theoretical curves,which verified that the parametric source measurement method was feasible.Then,the sound absorption properties of the rubber plate sample were measured under different hydrostatic pressures.The studying results could show that the parametric source measurement method had the potential application in the limited space water,such as the pressure vessel.     

兰州重离子冷却储存环二极磁铁设计

介绍了兰州重离子冷却储存环主环(CSRm)的改进W型二极磁铁和实验环(CSRe)C型二极磁铁的磁场计算和物理设计,在降低了磁铁造价和运行费用的前提下设计参数达到或超过了物理要求.根据样机的加工和检测结果来看,所有的磁场计算和物理设计的结果是可靠的.Magnetic field calculation and design of CSRm modified W-type dipoles and of CSRe C-type dipoles are presented in this paper. Under the condition of lower cost, all of the designed parameters are better than required values. Now the prototype has been fabricated and also the magnetic field measurement has been done. According to the measured results, all the calculation and design are very reliable.     

关于在HIAF-BRing上开展自旋物理研究的提议(英文)

国家重大科技基础设施"强流重离子加速器装置"（High Intensity heavy-ion Accelerator Facility,HIAF）已由国家发改委批准立项并开始建设。建成之后,HIAF将为微观物质结构和重离子应用等研究提供很好的实验平台。HIAF的加速储存环（Booster Ring,BRing）设计可以加速最高动量为11.9 GeV/c的高流强质子束流。因此,HIAF-BRing将为GeV能区的核物理和强子物理研究带来新的机遇。另一方面,极化实验是研究微观物质及其相互作用的有力工具。我们提议启动相关物理和极化技术的预研工作,为在HIAF-BRing上开展自旋物理研究打下基础。The construction of the future scientific facility High Intensity heavy-ion Accelerator Facility (HIAF) in China has started. Once established, HIAF will provide excellent conditions for fundamental investigations on both matter structure and heavy-ion applications. The booster ring (BRing) of HIAF is designed to accelerate high-intensity protons with the maximum momentum of 11.9 GeV/c. Therefore it will bring new opportunities for the nuclear and hadron physics in the GeV region. Polarized experiments have been proved as a powerful tool in the explorations of the building blocks of matter. We propose to initiate a pre-investigation for the related physics and polarization techniques, which will lay the foundation of the spin physics at the HIAF-BRing.     

强流重离子加速器装置的增强器慢引出系统

中国科学院近代物理研究所承担的强流重离子加速器装置目前已进入了初步设计阶段。增强器作为该装置的主加速器,可利用双向涂抹技术将238U35+束的粒子数累积至1.0×1011,并将其从注入能量为17 MeV/u加速至高能量,引出能量的范围为200-835 MeV/u。为了提供s量级的准连续束以开展辐照实验,增强器中设计了慢引出系统,该系统将采用三分之一共振与RF-knockout的引出方法。同步加速器中有两种不同种类的六极磁铁,用于实现色品校正与共振驱动,并在设计中考虑了两者能同时运行并互不影响。针对增强器中不同引出能量的238U35+束,对其相应的稳定接受度模拟结果进行了比较,并给出了在引出静电偏转板处的光学匹配参数,这将为增强器中重离子束的慢引出及放射性次级束流分离器的入口光学设计提供重要的理论依据。     

EAST真空室内巡视系统的真空性能研究分析

介绍了EAST真空室内巡视系统(IVVS)系统对EAST真空室第一壁进行巡检操作的工作原理,并基于系统部分材料出气率测试对其真空性能进行了分析。获得了在有效抽速为1064L•s^–1的条件下,IVVS系统试验样机所采用的真空容器的极限真空度为3.37×10^–3Pa。为优化IVVS真空性能,结合材料放气率试验,将部分材料更换为放气率低的材料,对系统进行烘烤处理,并对其中的相关结构提出了优化方案。优化后系统的真空性能有明显提高,在同等抽速条件下的极限真空度在1×10^–4Pa范围内,能够满足EAST接受的真空环境要求。此外,抽气机组增添低温泵可以更进一步提高系统的真空性能。     

锐钛矿金红石的高温原位X射线衍射研究

对TiO₂粉末进行了空气和真空条件下从室温到1200℃的加热原位X射线衍射实验, 得到了空气和真空条件下微米级锐钛矿颗粒转变为金红石的起始温度分别为850℃ 和855℃; 分别修正了空气条件下锐钛矿在(27–850℃)范围和金红石在(900–1200℃) 范围内的晶胞参数和真空条件下锐钛矿在(27–850℃)范围和金红石在(950–1200℃) 范围的晶胞参数, 从而得到了晶胞参数随温度变化的关系, 得到了锐钛矿和金红石在空气中和真空中的热膨胀系数, 并总结了热膨胀系数随温度变化的规律. 室温下锐钛矿在空气条件下的热膨胀系数为 α_a=4.55063×10^-6/℃, α_c=7.7543×10^-6/℃, β=16.85836×10^-6/℃; 真空下为 α_a=4.69429×10^-6/℃, α_c=9.02850×10^-6/℃, β=18.69688×10^-6/℃. 室温下, 金红石在空气条件下的热膨胀系数为 α_a=6.81243×10^-6/℃, α_c=8.71644×10^-6/℃, β=22.22178×10^-6/℃; 真空条件下为 α_a=6.05834×10^-6/℃, α_c= 8.39280×10^-6/℃, β=20.52362×10^-6/℃. 关键词： 2')" href="#">TiO₂ 原位X射线衍射 相转变 热膨胀     

EAST�������Ѳ��ϵͳ����������о�����

介绍了EAST真空室内巡视系统(IVVS)系统对EAST真空室第一壁进行巡检操作的工作原理,并基于系统部分材料出气率测试对其真空性能进行了分析.获得了在有效抽速为1064L·s–1的条件下,IVVS系统试验样机所采用的真空容器的极限真空度为3.37×10–3Pa.为优化IVVS真空性能,结合材料放气率试验,将部分材料更换为放气率低的材料,对系统进行烘烤处理,并对其中的相关结构提出了优化方案.优化后系统的真空性能有明显提高,在同等抽速条件下的极限真空度在1×10–4Pa范围内,能够满足EAST接受的真空环境要求.此外,抽气机组增添低温泵可以更进一步提高系统的真空性能.     

HIAF随机冷却系统slot-ring型pickup/kicker及相应合路器/功分器的设计与仿真

为降低束流发射度,提高束流强度,得到高品质的束流,强流重离子加速器装置(HIAF)高精度环形谱仪(SRing)将建造随机冷却系统。随机冷却系统的关键硬件pickup/kicker在一定程度上决定了其冷却效率。本工作讨论了随机冷却系统pickup/kicker的具体作用及设计指标,介绍了分路阻抗概念。SRing随机冷却系统采用周期性单元结构slot-ring模型,利用高频结构仿真(HFSS)软件对其进行建模并仿真优化。通过对不同结构参数进行扫参,确认了slot-ring结构各参数对pickup/kicker分路阻抗值的影响。仿真结果表明,slot-ring结构有较高的分路阻抗,适用于SRing随机冷却系统。同时,考虑到pickup/kicker工作带宽内分路阻抗的平坦度,提出了采用不同尺寸slot-ring结构进行组合的方式来优化其平坦度。最后设计并加工实测了该slot-ring结构相匹配的十六路功率分配器/功率合成器,实测结果表明:该功分器/合路器具有各端口输出幅度平坦度较好、隔离度大、插入损耗低、电压驻波比小等特点,满足SRing随机冷却系统的要求。