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.     

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.     

HIAF高能辐照终端感生放射性

本工作是基于蒙特卡罗模拟软件FLUKA对高能强流重离子加速器（HIAF）高能辐照终端感生放射性进行初步研究。该终端可运行质子最高能量为9.3 GeV,最大流强是1.45×1012 pps（particle per second）。研究内容包括:（1）预测高能辐照终端内活化物质的放射性活度特性;（2）预测不同冷却时间高能辐照终端内残余剂量率分布。研究结果表明,HIAF正常运行时高能辐照终端内的感生放射性主要受束流垃圾桶活化产生的放射性核素影响。当加速器连续运行100天冷却4小时,垃圾桶表面残余剂量率为2.375 mSv·h-1。终端内空气中13N和15O动态饱和比浓度大于其对应的导出空气浓度。冷却水中13N和15O的活度大于对应的ALI_min。该研究是HIAF辐射防护基础研究以及加速器环境影响评价的一项重要内容。The Monte Carlo code FLUKA was used to predict the induced radioactivity of high-energy irradiation terminal of HIAF. The maximum energy of proton is 9.3 GeV, and the maximum current is 1.45×1012 pps (particle per second). In this study we were to predict:(1) the activity properties of activated substances in the experimental terminal; (2) the residual dose rate distribution in the experimental terminal at different cooling time. The results indicate that the induced radioactivity in the high energy irradiation terminal of the HIAF is mainly affected by the radionuclide induced in the beam dump. The residual dose rate on the surface of the beam dump is 2.375 mSv·h-1, after 100 d irradiation and 4 h cooling. The dynamic saturation ratio of 13N and 15O induced in the air inside the terminal is higher than its corresponding derived air concentration. The activity of 13 N and15O induced in cooling water is higher than its ALI_min. This study is a part of radiation protection basic research and environmental impact assessment for HIAF.     

面向空间高能重离子与辐射屏蔽材料的反应截面地基研究

空间辐射尤其是高能重离子辐射可造成生物机体的严重损伤, 所以对高能重离子进行恰当的辐射屏蔽, 成为实现载人航天的关键性因素之一。 研究表明, 由于高能重离子与不同屏蔽材料发生相互作用, 所产生的核碎片等次级粒子, 直接影响空间辐射屏蔽材料的屏蔽性能研究和屏蔽结构设计。 介绍了太空辐射的分类与组成, 综述了国际地基辐射屏蔽材料与实验现状。 根据文献中的地基实验数据, 重点描述了被动式屏蔽方法: 以相近能量多种重离子, 不同能量的56Fe和28Si重离子分别与C, H, Al和Cu材料相互作用的总反应截面和碎片产生截面, 并结合510 MeV/u 56Fe与不同厚度CH2相互作用产生的碎片通量分布、 碎片平均LET分布和不同厚度CH2的单位入射离子剂量减少量等方面, 系统讨论分析了C, H, Al, Cu和CH2等常用空间辐射屏蔽材料的屏蔽性能。 Cosmic radiation, particularly the high energy heavy ion radiation, may cause serious injury on living organism. Therefore, it is one of critical restriction factor in Manned Spaceflight. Studies show that high energy heavy ions interacting with the shielding materials can produce numerous kinds of fragments and secondaries. These particles have a direct impact on evaluation of shielding properties of different shielding materials, the optimal shielding structure design and low dose evaluation after shielding materials. From perspectives of divisions of cosmic rays and passive shielding methods, this paper introduces the ground based research of shielding materials. The passive shielding method was discussed, based on the experimental data of the total cross sections and fragment（production） cross sections of the aspects of different heavy ions with approximately same energy and 56Fe, 28Si heavy ions with different energies on H, C, CH2, Al and Cu radiation shielding materials. In addition, the fragment fluency distribution, the average LET distribution and the dose reduction per particle of 510 MeV/u 56Fe in different depth of CH2 material were also discussed.     

高能质子引起器件单粒子效应的研究方法

简略介绍了高能质子在半导体芯片中引起单粒子效应的实验测量和理论分析方法,包括核反应分析方法、半经验方法,介绍了质子和重离子翻转截面间的关系,并用重离子实验数据预测器件在质子环境下的翻转率. This article introduces briefly the experimental and theoretical methods that have been used to study high energy proton induced single event effect in semiconductor devices. The theoretical methods including nuclear reaction analysis method and semi empirical method are presented. The relationship of upset cross section between proton and heavy ions is described. Finally, on orbit proton upset rates are predicted by using the heavy ion test data.     

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.     

基于HIAF的物理研究(英文)

在2010年,中国科学院近代物理研究所向国家发展和改革委员会建议了重大科技基础设施--强流重离子加速器装置（High Intensity Heavy-ion Accelerator Facility,简称HIAF）。经过一系列评估和论证,HIAF于2015年12月被国家发展改革委立项。HIAF建设地址位于广东省惠州市,计划于2018年年底正式开工建造。HIAF由超导直线加速器、同步增强器、高能放射性束流线、储存环谱仪以及若干实验测量装置构成,总投资约为25亿人民币。依托HIAF,我们将拓展核素存在版图,研发先进实验技术和方法,开展前沿物理研究;同时,开展重离子束应用研究,服务国家经济社会发展。简要介绍拟建的加速器系统、实验测量装置以及相关的物理研究计划。The Institute of Modern Physics, Chinese Academy of Sciences, proposed the Major National Science and Technology Infrastructure Facility named as High Intensity Heavy-ion Accelerator Facility (HIAF) in 2010. After a series of assessments charged by the National Development and Reform Commission of China, HIAF was officially approved by China government in December, 2015. HIAF will be constructed in Huizhou, Guangdong Province, and the groundbreaking ceremony of construction is scheduled around the end in the year of 2018. HIAF is composed of a superconducting Linac, a booster ring, a high-energy radioactive beam line, a storage ring, and a number of experiment setups. The total investment of HIAF is about 2.5 billion Chinese Yuan. The major goals for HIAF are to explore the hitherto unknown territories in nuclear chart, to approach the experimental limits, to open new domains of physics researches in experiments, and to develop new ideas and heavy-ion applications beneficial to the societies. In this paper, the accelerator complex of HIAF is briefly introduced, and the experimental setups and associated physics research program are presented.     

Effect of entrance-channel asymmetry on the isospin dependence of nucleon emission in heavy ion collisions

Using the isospin- and momentum-dependent hadronic transport model IBUU04, we have investigated the influence of the entrance-channel isospin asymmetry on the sensitivity of the pre-equilibrium neutron/proton ratio to symmetry energy in central heavy-ion collisions induced by high-energy radioactive beams. Our analysis and discussion are based on the dynamical simulations of the three     

Simulation of the response functions of an extended rangeneutron multisphere spectrometer using FLUKA

In this paper, the distribution of radiation field in the CSNS spectrometer hall at Dongguan, China, was simulated by the FLUKA program. The results show that the radiation field of the high energy proton accelerator is dominated by neutron radiation, with a broad range of neutron energies, spanning about eleven orders of magnitude. Simulation and calculation of the response functions of four Bonner spheres with a simplified model is done with FLUKA and MCNPX codes respectively, proving the feasibility of the FLUKA program for this application and the correctness of the calculation method. Using the actual model, we simulate and calculate the energy response functions of Bonner sphere detectors with polyethylene layers of different diameters, including detectors with lead layers, using the FLUKA code. Based on the simulation results, we select eleven detectors as the basic structure for an Extended Range Neutron Multisphere Spectrometer (ERNMS).     

医用质子和12C离子束的物理性质研究

质子和重离子在现代放射治疗手段中已起着不可替代的作用， 这主要取决于其独特的物理性质。 利用一步过程和两步过程的物理模型解释了离子能量损失的机制， 同时结合Geant4软件包模拟质子和12C在水中的运输过程， 研究了离子束的物理性质， 并讨论了计算的结果， 说明了质子和12C在医学中应用的优缺点。 Depending on their unique physical properties， proton and heavy ions have taken an irreplaceable role in modern means of tumor treatment. One step process and two step process physical models were employed to explain the mechanism of ion energy loss. The transport process of proton and 12C in water was simulated by Geant4 toolkit to study the physical properties of ion beam. The calculation results were discussed， which showed the advantages and disadvantages of proton and 12C in the medical application.     

Moyer模式在高能重离子加速器辐射防护屏蔽设计中的应用

叙述了Moyer模式在高能重离子加速器屏蔽设计中的应用.介绍了Moyer参数的选择,给出了束流的点源损失和无限或有限均匀线源损失的屏蔽计算方法.给出了根据天空反照剂量限值估算屋顶屏蔽厚度的方法.计算结果与Monte Carlo方法进行了比较.     

The simulated workplace field with a high-energy neutron component produced by irradiating a Fe-target with 200 MeV/u 12C-ions

Recent developments in accelerator physics have led to new challenges for radiation protection dosimetry. Doses have to be determined for workplace fields which are characterized by high-energy radiation, a dominant contribution from neutrons, high intensities and pulsed time structure This may present problems for active measuring devices. As is well known, the ambient dose equivalent is often underestimated by area monitors operating in high-energy neutron fields behind shielding. Therefore, it is desirable to calibrate survey monitors in a characterized neutron field with the type of spectral fluence distribution that is expected behind shielding, i.e. where the main dose from neutrons arises from two peaks with mean energies of about 1 MeV and 100 MeV, respectively. Such a neutron fluence distribution is produced by the irradiation of a Fe-target with 200 MeV/u ¹²C-ions. Measurements with the extended range Bonner sphere spectrometer NEMUS of PTB were performed at two positions inside the experimental area Cave A of the heavy-ion synchrotron SIS at GSI. The measured neutron spectra show different fluence contributions for the two peaks at the two positions. The results were compared to Monte Carlo Simulations with MCNPX and FLUKA.     

Comparison of Proton Shower Developments in the BGO Calorimeter of the Dark Matter Particle Explorer between GEANT4 and FLUKA Simulations

The DArk Matter Particle Explorer(DAMPE) is a satellite-borne detector for high-energy cosmic rays and y-rays. To fully understand the detector performance and obtain reliable physical results, extensive simulations of the detector are necessary. The simulations are particularly important for the data analysis of cosmic ray nuclei, which relies closely on the hadronic and nuclear interactions of particles in the detector material. Widely adopted simulation softwares include the GEANT4 and FLUKA, both of which have been implemented for the DAMPE simulation tool. Here we describe the simulation tool of DAMPE and compare the results of proton shower properties in the calorimeter from the two simulation softwares. Such a comparison gives an estimate of the most significant uncertainties of our proton spectral analysis.     

Simulation of Space Shuttle neutron measurements with FLUKA

FLUKA is an integrated particle transport code that has enhanced multigroup low-energy neutron transport capability similar to the well-known MORSE transport code. Gammas are produced in groups but many important individual lines are specifically included, and subsequently transported by the main FLUKA routines which use a modified version of EGS4 for electromagnetic (EM) transport. Recoil protons are also transported by the primary FLUKA transport simulation. The neutron cross-section libraries employed within FLUKA were supplied by Giancarlo Panini (ENEA, Italy) based upon the most recent data from JEF-1, JEF-2.2, ENDF/B-VI, JENDL-3, etc. More than 60 different materials are included in the FLUKA databases with temperature ranges including down to cryogenic temperatures. This code has been used extensively to model the neutron environments near high-energy physics experiment shielding. A simulation of the Space Shuttle based upon a spherical aluminum equivalent shielding distribution has been performed with reasonable results. There are good prospects for extending this calculation to a more realistic 3-D geometrical representation of the Shuttle including an accurate representation of its composition, which is an essential ingredient for the improvement of the predictions. A proposed project to develop a combined analysis and simulation package based upon FLUKA and the analysis infrastructure provided by the ROOT software is under active consideration. The code to be developed for this project will be of direct application to the problem of simulating the neutron environment in space, including the albedo effects.     

400 MeV/u碳离子打靶的屏蔽参数计算

为了给医用重离子加速器提供一种专用的快速计算屏蔽厚度或对蒙特卡罗模拟结果进行验证的方法。采用FLUKA程序完成了400 MeV/u碳离子打不同靶的屏蔽参数计算。首先研究了打厚靶(铁、水)产生的次级辐射场的角度分布及主要成分;接着给出了不同角度范围下周围剂量当量在屏蔽体中的衰减曲线,通过拟合数据进一步得到不同角度范围下的辐射源项值H₀和衰减长度λ₀;最后结合莆田市医用重离子加速器治疗室的屏蔽设计,介绍了此套屏蔽参数的使用方法,通过与蒙特卡罗模拟结果的对比,证明了这套屏蔽参数的可靠性。该参数可为同类医用重离子加速器的屏蔽设计提供可靠的参考数据。     

HIAF及CiADS项目进展与展望

强流重离子加速器（HIAF）及加速器驱动嬗变研究装置（CiADS）是"十二五"期间国家优先安排建设的16项中的重大科技基础设施。本文介绍了HIAF及CiADS项目意义、科学目标、装置构成及主要特点,对项目实施进展进行了阶段性总结,并对未来发展进行了展望。High Intensity heavy-ion Accelerator Facility (HIAF) and China initiative Accelerator Driven System (CiADS) are among 16 national research facilities built as a priority during China's Twelfth Five Year Plan. In this paper, the scientific feasibility, structures and the features of HIAF and CiADS are briefly summarized. Meanwhile, their present construction progresses are reported and their developments in the near future are outlined.     

Antiproton production in heavy-ion collisions at subthreshold energies

Within the framework of the Lanzhou quantum molecular dynamics model,the deep subthreshold antiproton production in heavy-ion collisions has been investigated thoroughly.The elastic scattering,annihilation and charge exchange reactions associated with antiproton channels are implemented in the model.The attractive antiproton potential extracted from the G-parity transformation of nucleon selfenergies reduces the threshold energies in meson-baryon and baryon-baryon collisions,and consequently enhances the antiproton yields to some extent.The calculated invariant spectra are consistent with the available experimental data.The primordial antiproton yields increase with the mass number of the colliding system.However,annihilation reactions reduce the antiproton production which becomes independent of the colliding partners.Anti-flow phenomena of antiprotons correlated with the mean field potential and annihilation mechanism is found by comparing them with the proton flows.Possible experiments at the high-intensity heavy-ion accelerator facility(HIAF) in China are discussed.