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.     

近Bohr速度的152Eu20+入射Au表面产生的X射线谱

测量了动能为2.0–6.0 MeV的高电荷态离子¹⁵²Eu²⁰⁺ 入射Au表面产生的特征X射线谱, 结果表明, 相互作用不仅激发出了Au的 M_ζ, M_α和M_δ特征X射线, 还激发出了Eu的M_α X射线, 且X射线总产额随入射离子动能的增加而增加. 计算了Au的M壳层总的X射线产生截面, 并与理论模型的计算结果做了比较分析. 关键词： 高电荷态离子 X射线 产额 截面     

Nd L-shell x-ray emission induced by light ions

The L-shell x-ray of Nd has been obtained for 300-600 keV He²⁺ ions impacting, and compared with that produced by H⁺ and H₂⁺ ions. The threshold of projectile kinetic energy for L-shell ionization of Nd is crudely verified in the energy region of about 300-400 keV. It is found that the energy of the distinct L-subshell x-rays has a blue shift. The relative intensity ratios of Lβ_{1, 3, 4} and Lβ_{2, 15} to Lα_{1, 2} x-ray are enlarged compared to the atomic data, and they decrease with the increase of the incident energy, and increase with increasing the effective nuclear charge of the incident ions. That is interpreted by the multiple ionization of outer-shells induced by light ions.     

Study of the PIN detector's radiation tolerance

PIN detectors have been extensively used to detect charged particles and X-ray. The new type PIN detectors were irradiated by different energy protons, and their irradiation tolerance was investigated. Relative charge collection efficiency, energy spectrometer and relative energy resolution were also measured. With the increasing of irradiation dose, charge collection efficiency decreased and relative energy resolution grown. The results suggested that the irradiation tolerance in the PIN detector depended on the range of the protons in the detector. The maximum tolerance irradiation doses of the detector for the impacts of 3.5 and 7.2 MeV protons were 3×10¹⁰p/cm² and 7.2×10⁹p/cm², respectively.     

高电荷态离子与SiO2表面相互作用的研究

高电荷态离子(Pbq ,Arq )由兰州近代物理研究所的ECR实验平台所产生,轰击非晶态SiO2表面.用微通道板测量溅射粒子产额的角分布.用公式拟合实验溅射角分布得到了较好的结果,并给出了初步的理论解释.由此得出了高电荷态离子与SiO2表面作用的微分溅射截面.实验结果表明高电荷态离子能够增加动能溅射;同时高电荷态离子入射能够引起势能溅射.在大角度入射时,溅射产额主要是由碰撞引起的;在小角入射时势能溅射所占比重会增大.     

高能电子成像暗场成像技术特性研究及改进方案

基于EGS5与PARMELA模拟软件组成的高能电子成像系统,对暗场成像的模拟研究发现,通过调节光阑位置实现的暗场成像结果存在失真现象。针对该失真现象提出的改进方案,消除了暗场成像结果的失真。通过对40 MeV电子透射7~224 μm的铝样品开展的成像模拟结果表明:40 MeV高能电子暗场成像技术在铝样品厚度小于25 μm情况下具有明显的面密度分辨优势,且空间分辨率达到μm量级,非常适用于高能量密度物质诊断。     

Areal density and spatial resolution of high energy electron radiography

Ultrafast imaging tools are of great importance for determining the dynamic density distribution in high energy density(HED) matter. In this work, we designed a high energy electron radiography(HEER) system based on a linear electron accelerator to evaluate its capability for imaging HED matter. 40 MeV electron beams were used to image an aluminum target to study the density resolution and spatial resolution of HEER. The results demonstrate a spatial resolution of tens of micrometers. The interaction of the beams with the target and the beam transport of the transmitted electrons are further simulated with EGS5 and PARMELA codes, with the results showing good agreement with the experimental resolution.Furthermore, the experiment can be improved by adding an aperture at the Fourier plane.     

重离子轰击Ta靶引起的多电离效应

在兰州重离子加速器国家实验室分别测量了H⁺, He²⁺, Ar¹¹⁺和Xe²⁰⁺离子轰击Ta表面过程中辐射的X射线谱, 并得到了Ta特征X射线谱中M_γ (M₃N₅)和N_αβ (M_4,5N_6,7)线的强度, 即I_γ和I_αβ. 分析结果表明, 强度比值I_γ/I_αβ 随着入射离子原子序数的增加而显著增加, 这是由于碰撞过程中Ta原子的多电离效应使M₃支壳层的荧光产额ω₃产生了显著增强.     

X-ray emission from 424-MeV/u C ions impacting on selected target

The K-shell x-rays of Ti, V, Fe, Co, Ni, Cu, and Zn induced by 424-MeV/u C~(6+) ion impact are measured. It is found that the K x-ray shifts to the high energy side and the intensity ratio of Kβ/Kα is larger than the atomic data, owing to the L-shell multiple-ionization. The x-ray production cross sections are deduced from the experimental counts and compared with the binary encounter approximation(BEA), plane wave approximation(PWBA) and energy-loss Coulomb-repulsion perturbed-stationary-state relativistic(ECPSSR) theoretical predictions. The BEA model with considering the multipleionization fluorescence yield is in better consistence with the experimental results. In addition, the cross section as a function of target atomic K-shell binding energy is presented.