320KV-ECR离子源表面物理实验终端

建成了兰州重离子加速器国家实验室320KV—ECR离子源表面物理实验终端，阐述了该实验终端的关键技术参数，描述了即将开展的高电荷态离子与表面相互作用的物理研究工作及其研究意义．     

Ar的类氦和类锂离子与Mo表面相互作用过程中的x射线发射

在兰州重离子加速器国家实验室电子回旋共振离子源上用Si(Li)探测器观测到了不同动能的Ar¹⁵⁺和Ar¹⁶⁺离子与Mo表面相互作用过程产生的x射线.在不同动能 的Ar¹⁶⁺与Mo表面作用过程中不仅能观测到Ar的K层x射线而且能观测到Mo的L层x 射线.在不同动能的Ar¹⁵⁺入射下只能观测到Mo的L层x射线.实验结果表明，Ar的 K层x 射线的产额与入射离子的动能、作用过程中形成的空心原子携带的势能以及入射离子和靶原 子x射线的竞争等有关，Mo的L层x射线随入射离子动能的增加而增加. 关键词： x射线发射 高电荷态离子 Mo表面     

320KV-ECR离子源表面物理实验终端

建成了兰州重离子加速器国家实验室320KV-ECR离子源表面物理实验终端,阐述了该实验终端的关键技术参数,描述了即将开展的高电荷态离子与表面相互作用的物理研究工作及其研究意义.     

极化效应对Bohr速度能区O5+离子在低密度氢等离子体中的能损影响

基于HIRFL加速器装置的低能束实验平台,实验测量了1.07 MeV(～66.9 keV/u)高电荷态O⁵⁺离子穿过中性氢气和部分电离的低密度氢等离子体靶后的能量损失,观测到等离子体中离子能损减小的新实验现象.分别考虑部分电离等离子体对炮弹离子的电荷屏蔽效应以及靶区原子的极化效应(Barkas修正),重新计算了离子能损,讨论了离子能损减小的可能物理机制.研究结果表明:在部分电离的低密度等离子体中,靶区的原子极化效应将显著影响Bohr速度能区离子的能量损失过程.     

近玻尔速度能区高电荷态离子与激光等离子体相互作用实验研究装置

近玻尔速度能区高电荷态离子在稠密等离子体中的能量损失是强流重离子束驱动的高能量密度物理等前沿研究中的核心物理问题之一.基于中国科学院近代物理研究所的320 kV实验平台,新建立了一套近玻尔速度能区离子束与激光等离子体相互作用的实验研究装置,用于开展高精度的离子能量损失和电荷态研究.本文将详细介绍该装置的特点,包括脉冲离子束(≥200 ns)的产生与调控、高密度(10¹⁷—10²¹ cm^–3)激光等离子体靶的制备、等离子体参数诊断与离子的高精度测量(<1%)等.基于该装置已开展了百keV的质子束和4 MeV的Xe¹⁵⁺离子束与激光Al等离子体靶相互作用的实验,并取得了相应的结果.本实验装置能够为中国在近玻尔速度能区高电荷离子与稠密激光等离子体相互作用研究提供高精度的实验数据,以促进理论工作的发展.     

HT—6M上电荷交换中性粒子能谱测量

用10道电荷文换中性粒子分析器测量了HT-6M装置的中性粒子能谱,给出了测量和数据处理方法以及在欧姆加热,高能中性粒子束(NBD)和离子回旋共振辅助加热(ICRH)条件下的能谱和离子温度,并对结果进行了分析讨论。     

用于CSRe上16O5+离子精密激光谱学实验的极紫外光子探测系统的研制

高电荷态离子的精密谱学研究不仅为强场QED效应、相对论效应、电子关联效应等基础前沿理论模型的精确检验提供了良好的条件,而且对同位素移动、高电荷态离子光钟等诸多前沿物理研究具有重要意义。为了在兰州重离子加速器冷却储存环的CSRe上开展相对论能量类锂16O5+离子2s_1/2→2p_1/2和2s_1/2→2p_3/2光学跃迁精密测量的激光谱学实验研究,研制了一套适用于前向发射荧光收集测量的新型非拦截式极紫外光子探测系统。该探测系统主要由抛物面型SiC反射镜、镀有CsI的微通道板(MCP)探测器以及高速步进电机等部分组成。在CSRe的高温烘烤环境和超高真空实验环境下,该探测系统能够在不影响储存环内离子束正常运转的同时实现对极紫外波段(50~200 nm)前向发射光子的高效探测,其探测效率较CSRe上现有光子通道倍增管荧光探测器提升约50倍。该探测系统不仅能够为CSRe上高电荷态离子的精密激光谱学实验提供高效实时的探测工具,亦为将来在大科学装置HIAF上开展更高能量、更高电荷态重离子的精密激光谱学实验研究奠定了坚实的基础。     

电子束离子阱光谱标定和Ar13+离子M1跃迁波长精密测量

高电荷态离子精细结构跃迁波长的精密测量不仅可以检验量子电动力学(quantum electrodynamics,QED)效应、电子关联效应等基本物理模型,还能够为天体物理、聚变等离子体物理甚至高电荷态离子光钟等研究提供关键原子物理数据.本工作基于复旦大学现代物理研究所的高温超导电子束离子阱(SHHtscEBIT)装置,搭建了一套新的光谱校刻系统,并结合内校刻与外校刻的方法对其光谱波长测量的不确定度进行了评估,新的光谱校刻系统在可见光波段引起的波长不确定度最低达到0.002 nm.在此基础上,使用SH-HtscEBIT装置结合新的校刻系统开展了Ar1³⁺离子1s²2s²2p²P_1/2—²P_3/2磁偶极跃迁(M1)波长的精密测量,实验测得该跃迁波长为(441.2567±0.0026) nm,是目前SH-HtscEBIT上测量精度最高的实验结果,为下一步开展高电荷态离子超精细分裂和同位素位移等精密测量实验奠定了基础.     

用于高电荷态离子与表面相互作用研究的原子物理实验平台

在重离子加速器国家实验室ECR离子源上,成功组建了用于高电荷态离子与表面相互作用研究的原子物理实验平台;利用该实验平台,研究了用不同电荷态和不同速度的高电荷态离子与不同表面相互作用的可见光和X射线发射的情况,同时还研究了高电荷态Xe离子轰击晶体材料所引起的材料性质和表面结构变化的情况.     

高电荷态离子207Pbq+(24≤q≤36)与Si(110)固体表面作用的电子发射研究

报道了利用兰州重离子加速器国家实验室ECR源引出的高电荷态离子207Pbq+(24≤q≤36)入射到Si(110)表面产生的电子发射的实验测量结果.结果表明,高电荷态离子与固体表面相互作用产生的电子发射产额Y与入射离子的电荷态q、入射角度ψ和入射能量E都有很强的关联.首次发现,电子发射产额Y与入射角度ψ间有接近1/tanψ的关系.理论分析认为,这些过程与基于经典过垒模型的势能电子发射过程密切相关.     

Response of HD-V2 radiochromic film to argon ions

A two-dimensional dose detector for ion beam is required in many high energy density physics experiments. As a solid detector, the GAFChromic film offers a good spatial resolution and dosimetric accuracy. For an absolute dose measurement, the relative effectiveness, which represents the darkening efficiency of the film to a radiation source, needs to be taken into consideration. In this contribution, the dose-response of HD-V2 to argon ions is presented for the first time. The calibration was taken over the dose range of 65 Gy-660 Gy with 8-keV argon ions. The response of net optical density is from 0.01 to 0.05. Triple-color dose-response functions are derived. The relative effectiveness for the argon ion beams is about 5%, much lower than that of protons and carbon ions. To explain this effect, the inactivation probability based on track theory of ion bombardment is proposed. Furthermore, a theoretical prediction of the relative effectiveness for single ion is presented, showing the dependence of the darkening efficiency on the atomic number and the incident energy of ions.     

The REX-ISOLDE project

The Radioactive Beam Experiment REX-ISOLDE [1–3] is a pilot experiment at ISOLDE (CERN) testing the new concept of post acceleration of radioactive ion beams by using charge breeding of the ions in a high charge state ion source and the efficient acceleration of the highly charged ions in a short LINAC using modern ion accelerator structures. In order to prepare the ions for the experiments singly charged radioactive ions from the on-line mass separator ISOLDE will be cooled and bunched in a Penning trap, charge bred in an electron beam ion source (EBIS) and finally accelerated in the LINAC. The LINAC consists of a radiofrequency quadrupole (RFQ) accelerator, which accelerates the ions up to 0.3 MeV/u, an interdigital H-type (IH) structure with a final energy between 1.1 and 1.2 MeV/u and three seven gap resonators, which allow the variation of the final energy. With an energy of the radioactive beams between 0.8 MeV/u and 2.2 MeV/u a wide range of experiments in the field of nuclear spectroscopy, astrophysics and solid state physics will be addressed by REX-ISOLDE. This revised version was published online in July 2006 with corrections to the Cover Date.     

锂玻璃探测器中子探测效率的刻度

为了精确测量keV能区的中子俘获截面,中国原子能科学研究院正在建造一台4π 全吸收型γ 探测装置---GTAF,锂玻璃探测器将会作为中子束流监视器测量中子能谱。利用5SDH-2 加速器刻度了锂玻璃探测器在两个入射中子单能点(250 和565 keV) 的探测效率,并使用EANT4 和MCNP 程序模拟计算了锂玻璃探测器的相对探测效率。通过归一化实验数据和模拟结果,得到了锂玻璃探测器在10keV~1 MeV 能区的中子探测效率曲线。对于把锂玻璃探测器测量得到的飞行时间谱转化为中子束流能谱,是一项非常重要的工作,同时为探测器效率刻度提供了新方法。In order to accurately measure the neutron capture cross section in the energy range of keVMeV, 4 πgamma-ray total absorption facility (GTAF) is being constructed at China Institute of Atomic Energy (CIAE). The lithium glass detector will be used as a neutron beam monitor for GTAF. The detection efficiency of the lithium glass detector at two incident neutron energy points (250, 565 keV) was calibrated in 5SDH-2 accelerator, and the relative detection efficiency was simulated by GEANT4 and MCNP code. By the normalization of the experimental data and simulation result, the neutron detection efficiency curve of the lithium glass detector between 10 keV and 1 MeV was obtained. This work will be important to convert the Time-of-flight spectrum that be measured by Li-glass detector to the energy spectrum of neutron beam, and provide the new method for calibration of detection efficiency.     

Hadronization and chirality in strongly interacting partonic matter — The future of the RHIC Program

New physics and detector concepts for a future pp and heavy ion program at the RHIC-II accelerator facility will be discussed. I will focus on hadronic observables which enable us to gain a better understanding on the hadronization from a sQGP and the chiral symmetry restoration in a sQGP. The ultimate question of how matter acquires mass can be addressed by this program in a complementary way to the Higgs search in high energy physics. The contributions of the RHIC program to the study of QCD will be discussed in detail.     

北京大学1.7MV串列静电加速器的离子注入/辐照实验系统

北京大学1.7 MV串列静电加速器运行至今已有三十多年.该加速器配备有高频电荷交换负离子源和铯溅射负离子源,能够引出从H到Au之间的大部分元素的离子.离子能量可被加速至几百keV到若干MeV,主要开展离子注入/辐照实验和卢瑟福背散射(RBS)和沟道分析等离子束分析工作.基于辐照实验需求,建立了高温辐照系统,温度最高可达...     

基于智能算法的CR39径迹刻蚀过程模拟

CR39可以用于激光等离子物理实验中的离子探测,并给出离子数目、种类和能量信息。通过采用唯象模型,利用离子在CR39中径迹形成的阻止本领动力学方程以及粒子群智能算法对径迹形成的过程进行了数值化模拟,研究了CR39中离子径迹在刻蚀过程中的演化过程,获得了入射离子能量和径迹直径、深度的对应关系,并且发现当离子射程与刻蚀深度相等时,径迹深度最大,给出了利用总刻蚀时间计算最大径迹深度对应的临界能量的公式。     

Commissioning and early experiments of the PHELIX facility

At the Helmholtz center GSI, PHELIX (Petawatt High Energy Laser for heavy Ion eXperiments) has been commissioned for operation in stand-alone mode and, in combination with ions accelerated up to an energy of 13 MeV/u by the heavy ion accelerator UNILAC. The combination of PHELIX with the heavy-ion beams available at GSI enables a large variety of unique experiments. Novel research opportunities are spanning from the study of ion–matter interaction, through challenging new experiments in atomic physics, nuclear physics, and astrophysics, into the field of relativistic plasma physics.     

Electron-ion collider in China

Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a po- larization of 80%) and protons (with a polarization of 70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2–3)×10³³ cm−2•s−1. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.     

一种校验带电粒子速度成像探测器的新方法

带电粒子(离子或者电子)速度成像技术可以精确测量带电粒子产物的速度分布和角分布,获得光谱级别分辨率的原子分子能级结构,广泛应用于光电离和光解离等分子反应动力学实验中.速度成像探测器的效率和信号相对强度对带电粒子速度分布信息的提取具有重要的影响.由于难以精确测量入射离子数,至今仍然没有直接校验速度成像探测器的方法报道.本文基于铷原子磁光阱搭建了一套离子速度成像实验装置,实现了入射离子数的精确测量及连续可调,并对冷原子的光电离过程、微通道板探测器采集的飞行时间信号、电荷耦合器件采集的荧光屏信号进行了校验,对可能影响速度成像信号相对强度的因素进行了检验.实验结果表明:当入射离子数低于1×105个/(100 ns)时,微通道板探测器的增益稳定,而荧光屏信号强度与入射其表面的电子数量的关系受荧光屏电压影响比较严重.同时,结果表明本方法可以有效校验带电粒子速度成像探测器的效率和信号的相对强度,对使用速度成像技术的实验具有一定的借鉴意义.