一台14.5GHz新型高磁场高电荷态ECR离子源

自行研制成功一台14.5GHz新型高磁场高电荷态电子回旋共振(ECR)离子源.描述了该离子源结构特点、参数优化及其磁场分布,并给出了调试测量结果.该离子源轴向磁镜场在轴线上的最高磁场可达1.5T,六极永磁体在弧腔内表面磁场可达1.0T.经初步调试,可得到0⁷+140eμA,Ar¹¹+185eμA,Xe²⁶⁺50eμA.所得结果与1998年国际上最好的ECR离子源进行了比较.     

强流高电荷态Pb离子束的产生与优化研究

随着原子物理及表面物理研究的发展,电荷态金属离子束的需求日益增多. 近来,中国科学院近代物理研究所,14.5GHz LECR3,离子源实验平台上, 以炉子法产生的铅离子束作为研究对象, 进行了一系列,ECR,离子源关键参数(如：磁场、炉子功率、掺气等)影响高电荷态铅离子束产额的实验研究, 在此基础上, 调整优化了,LECR3,离子源的状态参数, 从而获得了强流高电荷态铅离子束,18eμa ²⁰⁷Pb³⁰⁺,和6.7eμa ²⁰⁷Pb³⁷⁺.     

J/ψ共振参数的测定

利用北京正负电子对撞机(BEPC)和北京谱仪(BES),测量了e+e－对撞束在J/ψ共振峰附近能区内末态为强子、e⁺e^－和μ⁺μ^－的实验观测截面,对这些截面的拟合得到J/ψ衰变宽度和分支比的新的实验测定值:Γ=84.4±8.9keV,Γh =74.1±8.1keV,Γe=5.14±0.39keV,Γμ=5.13±0.52keV, /=(87.8±0.5)%,Γe/Γ=(6.09±0.33)%,Γh/Γ=(6.08±0.33)%.     

K+介子的三体轻子衰变

本文利用色散关系方法,假设普适V-A弱相互作用和奇异矢量流不守恒,从而对形状因子f₀,f₁的色散关系进行一次减去,计算了K_μ3⁺、K_e3⁺衰变中的π⁰能谱,K_μ3⁺衰变中的μ⁺能谱和μ⁺的纵向极化。计算中只考虑了K₁^*(m_*=888MeV)中间态对色散积分的贡献。参数σ取为+2.1的结果和实验在误差范围内相符合。放弃奇异矢量流部分守恒假设与实验符合的程度比保持这一假设要好一些。     

激光离子源的首次在线实验结果

介绍了在线同位素分离器使用激光离子源的重要性、激光离子源原理和相关激光技术,以及热毛细管激光离子源和靶室的结构.在首次在线实验中使用50MeV/u ¹⁸O+^natTa→¹⁶⁷Yb(T_1/2=17.5m)反应道,实现了加速器、分离器和激光系统的联合运行.通过测量分离后产物的γ谱,确定了分离后的¹⁶⁷Yb的产额,并与从产生截面、束流强度、收集时间和靶厚度计算得到的产生率相比,得到总分离效率约为0.2%.通过有激光与无激光条件下测量的γ谱中¹⁶⁷Yb与¹⁶⁷Lu相应峰下面积比值K得到元素选择性η为3.2.发现了新的¹⁶⁷Yb的长寿命高自旋的同质异能态,分析了提高效率的途径.     

Afterglow工作模式下ECR离子源脉冲束的产生

为满足国家大科学工程兰州重离子冷却储存环的要求,在14.5GHz ECR 离子源上进行afterglow工作模式的实验,首次产生了高电荷态脉冲束流Ar¹¹⁺和Ar¹²⁺,给出了初步实验结果,并对结果进行了分析和解释.     

单体迁移驱使的聚集体生长

本文提出了一个可解的聚集体生长模型。在系统中，在质量为l的B聚集体的作用下，一个单体从质量为i的A聚集体迁移到质量为j的A聚集体，这个迁移反应速率核为K(i;j;l) i^μ j^ν l^varpi（ω≥0）。利用平均场速率方程方法，本文得到了几种不同情况下的聚集体质量分布的解析解。对μ=ν的系统，在μ<3/2的情况下系统的聚集体质量分布a_k(t)具有一种普适的标度形式。对于μ≠ν的系统，只有在μ<ν和μ+ν<2的情况下a_k(t)才满足标度形式。同时，在μ+ν>2（μ≠ν）或者μ>3/2（μ=ν）的情况下，系统将发生类凝胶相变。此外，本文也研究了反应核为K(i;j;l)μ(i^μ j^ν+ i^νj^μ )lω的系统的动力学标度行为。结果表明，聚集体质量分布只有在μ+ν<3的情况下才遵循标度律，而在其他情况下系统将在足够长的时间后发生类凝胶相变。     

FLUORESCENCE MECHANISMS OF Tm3+- AND Yb3+/Tm3+ DOPED AlF3-BASED FLUORIDE GLASS

A complete set of spectroscopic parameters, including Judd-Ofelt parameters, radiative transition probabilities, radiative lifetime, branching ratios and integrated absorption cross section, have been calculated for Tm³⁺- doped fluoroaluminate (AYF) glass, based on the measured absorption spectra. The mechanism of Tm³⁺→Tm³⁺ and Yb³⁺\Leftrightarrow Tm³⁺ energy transfers and fluorescence properties have been investigated in both Tm³⁺ single-doped and Yb³⁺/Tm³⁺ double-doped AYF glasses. The cross-relaxation process, ³F₄+³H₆→2³H₄, is proved, which makes the optimum Tm³⁺ concentration of 1.77μm fluorescence (³H₄→³H₆) much higher than 1.45μm fluorescence (³F₄→³3H₄) in Tm³⁺:AYF glasses. In Yb³⁺/Tm³⁺:AYF glasses, a stronger concentration quenching is found for the 476nm emission than that for the 797nm emission, and is discussed under the 970nm-excitation.     

医用3μm与2μm级联振荡钬光纤激光器的工作原理与初步设计

分析了医用3μm与2μm级联振荡Ho³⁺:ZBLAN光纤激光器的工作原理,首次给出了1.1μm带泵浦下级联振荡Ho³⁺:ZBLAN光纤激光器的动态及稳态速率方程,最后给出了级联振荡Ho³⁺:ZBLAN光纤激光器的初步设计.     

高能正负电子对的湮没与超窄共振ψ粒子的作用

本文给出了R=(σ(e⁺e^-→强子))/(σ(e⁺e^-→μ⁺μ^-))随能量上涨的一个解释。研究了新发现ψ粒子所具有作用的性质,指出其强度f²/(4π)～10^-5—10^-6。求得峰值截面σ₀=(12π)/m_ψ²(Γ(ψ→e⁺e     

Sm3+在玻璃中的发光以及Sb6+、Ce6+、Gd3+对Sm3+发光性质的影响

本文研究了单掺(Sm3+,Ce3+、Gd3+.Sb3+、双掺(Sm3++Ce3+、Sm3++Gd3+,Sm3++Sb3+)和兰掺(Sm3++Gd3++Ce3+)约四十余种不同玻璃的发射谱和激发谱.探讨了玻璃成份和掺杂离子浓度对Sm3+发光性质的影响以及Ce3+,Gd3+、Sb3+、Ce3++Gd3+对Sm3+的敏化作用。     

Study on relationship of luminescence in CaS:Eu,Sm and dopants concentration

In order to study different characteristic luminescence of Eu²⁺ and Sm³⁺, delayed photoluminescence (DPL) and infrared stimulated luminescence (ISL) spectra of CaS doped with europium and samarium have been investigated. The influence of Eu and Sm concentration on luminescence of Eu²⁺ in photoluminescence (PL) and ISL was respectively studied. It was found that, at low doping levels, PL emission intensity of Eu²⁺ increased linearly with increment of Eu, while decreased linearly with increment of Sm. However, further increment of Eu and Sm in CaS:Eu,Sm could not increase either the luminescent centres of Eu²⁺ or electron trapping sites of Sm³⁺. Different local environment of Eu²⁺ and Sm³⁺ in the lattice position is thought to be the cause of all observed luminescence phenomena. Finally, the maximum emission in ISL was obtained at 1000 ppm europium and 750 ppm samarium.     

低能离子束横向发射度的测量及分析

The transverse emittance of an ion beam describes its transverse size as the particles are transported from a source to a target.It allows for predicting beam losses in limiting apertures and the beam focus size at the target.Various definitions and issues are discussed.The most common and emerging measuring techniques are presented,including their advantages.Several methods of emittance data analysis,their accuracy and trustworthiness,are discussed.     

Sm~(3+)在玻璃中的发光以及Sb~(6+)、Ce~(6+)、Gd~(3+)对Sm~(3+)发光性质的影响

本文研究了单掺(Sm~(3+),Ce~(3+)、Gd~(3+).Sb~(3+)、双掺(Sm~(3+)+Ce~(3+)、Sm~(3+)+Gd~(3+),Sm~(3+)+Sb~(3+))和兰掺(Sm~(3+)+Gd~(3+)+Ce~(3+))约四十余种不同玻璃的发射谱和激发谱.探讨了玻璃成份和掺杂离子浓度对Sm~(3+)发光性质的影响以及Ce~(3+),Gd~(3+)、Sb~(3+)、Ce~(3+)+Gd~(3+)对Sm~(3+)的敏化作用。     

空心圆管端点附近等离子体源离子注入过程中鞘层的时空演化

等离子体源离子注入过程中，鞘层的演化规律直接影响到离子注入到材料中的深度进而影响材料表面的性质和结构，对材料的不同部位这种影响是不同的.利用无碰撞两维流体动力学模型，研究了有限上升时间的电压脉冲作用下，共轴放置附加零电极的半无限空心圆管端点附近等离子体源离子注入过程中，鞘层的时空演化规律.通过计算得到了鞘层内随时间变化的电势分布和离子密度分布，计算了端点附近材料表面处的离子流密度分布和注入剂量分布随时间的变化规律.计算机模拟结果显示了空心圆管内部、外部及端点表面处的离子流密度分布和注入剂量分布存在很大差异.     

Improvement of the Applicability, Efficiency, andPrecision of the Penning Trap Mass Spectrometer ISOLTRAP

With the Penning trap mass spectrometer ISOLTRAP, close to 200 nuclides have already been investigated and their masses determined with a typical relative precision of δm/m=10⁻⁷. Recently, ISOLTRAP's beam preparation system was replaced by an RFQ ion beam cooler and buncher. The principle and the characteristics of this new beam preparation system will be presented. It is planned to use ions of various carbon clusters C⁺ _n (n>1) as reference ions for mass measurements. Apart from negligible molecular binding energies, these clusters have masses that are exact multiples of the unified atomic mass unit. This will allow ISOLTRAP to carry out absolute mass measurements as well as to investigate possible mass-dependent systematic errors. The results of tests of the production, transport, and trapping of such carbon clusters will be presented. This revised version was published online in July 2006 with corrections to the Cover Date.     

半圆形容器等离子体源离子注入过程中离子动力学的两维PIC计算机模拟

利用两维particle-in-cell方法研究了半圆形容器表面等离子体源离子注入过程中鞘层的时空演化规律. 详尽考察了鞘层内随时间变化的电势分布和离子密度分布规律,离子在鞘层中的运动轨迹和运动状态,得到了半圆容器内、外表面和边缘平面上各点离子注入剂量分布规律,获得了工件表面各点注入离子的入射角分布规律. 研究结果揭示了半圆容器边缘附近鞘层中离子聚焦现象,以及离子聚焦现象导致工件表面注入剂量分布和注入角度分布存在很大不均匀的基本物理规律. 关键词： 等离子体源离子注入 鞘层 两维particle-in-cell方法 离子运动轨迹     

ECR ion source based low energy ion beam facility

Mass analyzed highly charged ion beams of energy ranging from a few keV to a few MeV plays an important role in various aspects of research in modern physics. In this paper a unique low energy ion beam facility (LEIBF) set up at Nuclear Science Centre (NSC) for providing low and medium energy multiply charged ion beams ranging from a few keV to a few MeV for research in materials sciences, atomic and molecular physics is described. One of the important features of this facility is the availability of relatively large currents of multiply charged positive ions from an electron cyclotron resonance (ECR) source placed entirely on a high voltage platform. All the electronic and vacuum systems related to the ECR source including 10 GHz ultra high frequency (UHF) transmitter, high voltage power supplies for extractor and Einzel lens are placed on a high voltage platform. All the equipments are controlled using a personal computer at ground potential through optical fibers for high voltage isolation. Some of the experimental facilities available are also described.     

CSR放射性次级束流线

兴建中的放射性次级束流线,是兰州重离子冷却储存环中连接主环和实验环的束运线的主要部分.描述它的结构、离子光学,以及二、三阶像差校正.