复旦大学核微探针系统

复旦大学现代物理研究所利用国家“211工程”的资助，从英国Oxford Microbeams公司引进了微探针关键部件，建立了新的核微探针实验装置.介绍了该装置各个组成部分,包括束线，靶室，聚集、扫描系统以及数据采集系统等.现已得到线度为μm量级的离子束.A nuclear microprobe was set up at the Institute of Modern Physics of Fudan University.The key parts were imported from Oxford Microbeams Ltd.The hardware system of the microprobe,including beam line,target chamber,focusing system and DAQ system is introduced. About several micrometer could be achieved at present beam spot size.     

核探针技术及其应用

核探针的概念起源于电子探针,它综合了离子束分析技术的特点,已成为很有应用前景的分析工具.本文结合上海新建成的核探针,介绍它们的原理、结构和部分应用. In concept,the scanning nuclear microprobe is similar to the scanning electron micro-probe,but has much higher sensitivity for microanalysis.The main features and the construction of thenew-built Nuclear Microprobe in Shanghai are described.It has been proved to be an ideal tool for mi-croanalysis in the fields of medical and biology,metallurg,microelectronics,archaeology and earthsciences.Its potentiality is demonstrated with examples in the applications of these fields.     

Structure study of light unbound nuclei near drip line

Some experimental techniques and theoretical analysis on unbound nuclei structure study are briefly introduced in this article. The unbound nuclei structure investigation can inspect the reliability of theoretical calculation, and is also important to extend the modern nuclear structure model to exotic nuclear regions. With the recent development of radioactive Ion Beam (RIB) facility and some new experimental methods, the structure of unbound nuclei near drip line can be studied in experiment.     

离子微束技术及其多学科应用

通过微米孔准直或电磁聚焦技术可将加速器产生的MeV离子束形成微米尺寸的离子束斑(微束), 从而用来研究固体和生物样品的微米空间分辨的材料信息和辐照响应。 结合MeV离子微束的发展历史综述了微束技术和跨学科应用, 包括利用微束开展具有空间分辨的离子束分析、 单粒子效应、 微纳加工和细胞辐射响应等研究。 介绍了中国科学院近代物理研究所的高能重离子微束辐照装置, 该装置成功地将总能量为1 GeV的C离子在大气中聚焦为1 μm×2 μm的微米束斑。 Beam of MeV ions from particle accelerators can be confined by collimators or focused by electrical/magnetic quadruples into micrometer size, and this microbeam can be used to obtain spatial information or radiation effect in solids and biological samples. This paper reviews the technical developments and the multi disciplinary applications of microbeam, including ion beam analysis, single event effect in semiconductor devices, proton beam writing and cellular response to targeted particle irradiations. Finally, the high energy heavy ion microbeam facility at the Institute of Modern Physics of Chinese Academy of Sciences is introduced, which has successfully focused 1 GeV Carbon ions into a beam spot of 1 μm×2 μm in air.     

金属环境中低能D(d,p)T反应的研究

近年来一系列实验表明， 金属环境中的低能带电粒子引起的核反应截面与气体靶中的相比出现明显增大， 这种现象通常被归结为电子屏蔽效应。 全面介绍了金属环境中D(d, p)T反应电子屏蔽效应的测量方法、 数据分析和实验结果的规律性， 并简要论述了包括德拜等离子体模型在内的各种理论模型对实验结果的解释。 通过研究， 可以获得有关核物理、 核天体物理和凝聚态物理的宝贵知识。 The cross sections σ(E) of low energy nuclear reactions induced by charged particles in metallic environment are much larger than that in gas. Generally, it was taken as the effect of the electron screening. In this work, the experimental method of the D(d, p)T reaction in metallic environment was introduced. The data analysis and the regularity of experimental results were also discussed. All kinds of theoretical models including the Debye model were discussed, which can roughly explain the results of the experiments. The valuable knowledge of nuclear physics, nuclear astrophysics and condensed state physics can be obtained in the study of low energy nuclear reaction in metallic environment.     

逆运动学弹性共振散射方法在非束缚核结构研究中的应用

简要介绍了近几年发展起来的厚靶逆运动学弹性共振散射方法在非稳定核结构测量中的应用。它是研究非束缚态核结构的实验方法之一。通过测量反冲轻核的激发函数，提取共振态的能量、自旋宇称和衰变宽度等。主要用于研究非稳定核素的结构、核天体物理中相关核的阈能共振态的能级参数测量等。The method of elastic resonance scattering in inverse kinematics, which was progressed in recent years, is briefly introduced. It is a novel experimental technique to perform meaningful experiments under conditions of the very short-lived nuclides and the beam intensities only 1 000 atoms/s. The excitation function of recoil proton has been measured in experiment; the shape of proton energy spectrum can be also used to uniquely deter- mine the energy of resonant states, spin-parity, partial decay width and spectroscopic factors of the states. This method is mainly used in the investigation of unstable nuclei and the level parameters measurement of near threshold resonant state of the nuclear astrophysics related nuclei.     

Application of wavelet transform in-ray spectra analysis

The frequency distribution of different ingredients in-ray spectra,e.g.,photo-peak,fluctuations of counts and Compton region,is separately analyzed.After wavelet transform of-ray spectra,the wavelet coefficients of a photo-peak increase with transforming scales and these coefficients show direct proportion with intensity of peak at determinate scale.A novel algorithm based on wavelet transform is proposed and studied.The results indicate that most of the photo-peaks in multi-spectra can be determined accurately,the-rays energy and intensity of the peak can also be determined.This method has the prospect of being applied in on-line multi-spectra analysis in such fields as radioprotection and nuclear safety monitoring.     

兰州320kV高压平台低能核天体物理实验研究进展(英文)

在低温核天体物理环境下，如静态核稳定燃烧阶段的核反应都发生较低的能区，其伽莫夫窗口内的核反应截面非常小，这就需要加速器提供较强束流才能完成核反应截面的直接测量。最近在中国科学院近代物理的320 kV高压平台上建立了低能核天体物理实验室以及相应的研究平台。驱动该平台的是一个14.5 GHz的永磁铁型ECR离子源，它能够提供非常强的束流离子。对于质子和氦离子，离子源出口的最大流强可以达到100 eμA，在实验终端上可以获得大约30 eμA的流强。基于此强流加速器装置，我们建立了核天体物理实验测量装置，包括靶室以及带电粒子和伽玛射线探测器等设备。利用已知的核反应对探测器性能和实验方法进行了一系列测试。同时，展示了近年来取得的一些主要实验结果。最后，对该平台上开展工作的前景进行了展望，并指出基于该地面装置的低能核反应研究所积累的技术及经验对于我国锦屏深地核天体物理JUNA项目的重要意义。For the hydrostatic stable burning in stars, the Gamow window is well below the Coulomb barriers for the charged-particle-induced nuclear reaction involved. Such nuclear reaction occurs through the quantum-mechanics tunneling effect, and its cross section drops rapidly approaching the Gamow window. An accelerator which can provide intense beam current is thus required to directly measure the reactions at low energies. An experimental setup for low-energy nuclear astrophysics studies has been recently established at a 320 kV high-voltage platform of the Institute of Modern Physics (IMP), Lanzhou, China. The driver machine of this platform is a very strong ECR ion source employing all-permanent magnets, which can typically supply up to about 100 eμA proton, alpha and many other heavy ions, and ultimately about 30 eμA currents can be achieved at the experimental terminal. The experimental setup includes a target chamber, and the charged-particle and γ-ray HPGe detectors. This work describes the setup established, characteristics of detectors, methodologies, and test results of several reactions with known cross sections. Furthermore, some important results published are shown briefly. We believe that the experimental technologies developed and experiences accumulated at this above-ground platform will be extremely helpful for the Jinping Underground Nuclear Astrophysics laboratory (JUNA) project in China.     

核子微探针技术的发展及其应用研究

核子微探针的发展提供了一种在微米尺度内分析微量元素的强有力的工具，用它研究海洋矿物已成为一项热门的课题．因为象海洋锰结核和海山锰结壳这种海洋矿物的生长速率很慢，一百万年只长几毫米，用核子微探针能够直接地、仔细地观察这些矿物缓慢的生长过程．核子激探针能够测量单个细胞中微量元素的成分和分布，以及它们对生物的作用．它还能研究在球墨铸铁中微量元素的含量，以及它们对球化过程的影响．目前，ＳＩＮＲ核子微探针的空间分辨率是２ｍｍ，通过改进聚焦系统和扫描图像解卷积技术，分辨率将进一步提高．三维成像技术已经发展成一个重要分支，其中扫描透射显微技术（ＳＴＩＭ）是一个成功的例子．因为成像技术只需要非常小的束流强度，它有可能使核子微探针的分辨率达到纳米水平． The development of nuclear microprobe techniques provides a powerful means for micro-analysis in areas with micron scales. Great interest has been shown in the applications of the nuclear microprobe for investigating marine ores. Because the accumulations of marine ores, such as deep-sea ferromanganese nodules and seamount ferromanganese crusts,are very slow, about a few millimeters per million years, the ability of microscopic analysis of trace elements brings the nuclear microprobe...     

Multi-mode Spiral Wave in a Coupled Oscillatory Medium

Multi-mode spiral wave and its breakup in 1-d and 2-d coupled oscillatory media is studied here by theoretic analysis and numerical simulations. The analysis in 1-d system shows that the dispersion relation curve could be nonmonotonic depending on the coupling strength. It may also lead to the coexistence of different wave numbers within one system. Direct numerical observations in 1-d and 2-d systems conform to the prediction of dispersion relation analysis. Our findings indicate that the wave grouping can also be observed in oscillatory media without tip meandering and waves with negative group velocity can occur without inhomogeneity.     

Optimal laser pulse design for transferring the coherent nuclear wave packet of H+2

Within the Franck–Condon approximation, the single ionisation of H₂ leaves H⁺₂ in a coherent superposition of 19 nuclear vibrational states. We numerically design an optimal laser pulse train to transfer such a coherent nuclear wave packet to the ground vibrational state of H⁺₂. Frequency analysis of the designed optimal pulse reveals that the transfer principle is mainly an anti-Stokes transition, i.e. the H⁺₂ in 1sσ_g with excited nuclear vibrational states is first pumped to 2pσ_g state by the pulse at an appropriate time, and then dumped back to 1sσ_g with lower excited or ground vibrational states. The simulation results show that the population of the ground state after the transfer is more than 91%. To the best of our knowledge, this is the highest transition probability when the driving laser field is dozens of femtoseconds.     

Development Towards Muonic Atom Formation with Unstable Nuclei

We report on the latest development of a new method for extending muonic atom X-ray spectroscopy to the use of radioactive isotope beams to form muonic atoms with unstable nuclei. This would allow studies of the nuclear properties and nuclear sizes of unstable atoms by means of the muonic X-ray method at facilities where both negative muon and radioactive nuclear beams would be available. Progress of a feasibility study at RIKEN-RAL muon facility is also reported. This revised version was published online in August 2006 with corrections to the Cover Date.     

Proposal for X-ray spectroscopy of muonic atoms formed from implanted ions in solid hydrogen films

A new method is proposed to extend muonic atom X-ray spectroscopy to the study of nuclear beams, including radioactive beams, by stopping both muon and nuclear beams in a solid hydrogen film. The muon transfer reaction to higher Z nuclei is used then to form muonic atoms. This method would allow studies of the nuclear charge distribution of unstable atoms. This revised version was published online in August 2006 with corrections to the Cover Date.     

少周期XUV激光中氢分子离子单光子电离理论研究

通过数值求解二维含时薛定谔方程研究了氢分子离子在圆偏振XUV少周期激光电场中的单光子电离,结果观察到不同核间距的氢分子离子的光电子能谱的能移现象.分析表明,在少周期激光场宽频情况下,分子电离电子的双中心干涉改变了夫兰克-康登因子的单调递减趋势,使不同核间距氢分子离子的光电子能谱出现能量移动.     

用B样条函数计算氢分子离子的能级和波函数

采用B样条函数展开方法数值求解了氢分子离子的定态薛定谔方程,计算了不同核间距时氢分子离子的基态和第一激发态的能级,结果表明,将氢分子离子的核位置作为B样条函数的节点,即使对较大的核间距,基态和第一激发态的能级值仍可达到很高的精度,所得基态径向波函数与用GAUSSIAN化学软件计算的结果符合得很好.     

Application of microscopic transport model in the study of nuclear equation of state from heavy ion collisions at intermediate energies

The equation of state (EOS) of nuclear matter, i.e., the thermodynamic relationship between the binding energy per nucleon, temperature, density, as well as the isospin asymmetry, has been a hot topic in nuclear physics and astrophysics for a long time. The knowledge of the nuclear EOS is essential for studying the properties of nuclei, the structure of neutron stars, the dynamics of heavy ion collision (HIC), as well as neutron star mergers. HIC offers a unique way to create nuclear matter with high density and isospin asymmetry in terrestrial laboratory, but the formed dense nuclear matter exists only for a very short period, one cannot measure the nuclear EOS directly in experiments. Practically, transport models which often incorporate phenomenological potentials as an input are utilized to deduce the EOS from the comparison with the observables measured in laboratory. The ultrarelativistic quantum molecular dynamics (UrQMD) model has been widely employed for investigating HIC from the Fermi energy (40 MeV per nucleon) up to the CERN Large Hadron Collider energies (TeV). With further improvement in the nuclear mean-field potential term, the collision term, and the cluster recognition term of the UrQMD model, the newly measured collective flow and nuclear stopping data of light charged particles by the FOPI Collaboration can be reproduced. In this article we highlight our recent results on the studies of the nuclear EOS and the nuclear symmetry energy with the UrQMD model. New opportunities and challenges in the extraction of the nuclear EOS from transport models and HIC experiments are discussed.     

A Carbon-13 NMR Assignment Study of Certain 6-Substituted Dibenz [c,e] Azepine 5, 7-Dione

The natural abundance carbon-13 nuclear magnetic resonance spectra of diphenic acid and some 6-substituted dibenz [c,e] azepine, 5, 7-dione - which can be considered also as N-substituted diphenimide - were recorded using Fourier transform technique. The chemical shifts of various carbon resonance have been assigned on the basis of chemical shift theory, the signal multiplicity observed in the single frequency off-resonance decoupled (SFORD) spectra and comparison with the chemical shifts of the model compounds.     

Using short pulses to enhance the production rate of vibrationally excited hydrogen molecules in hydrogen discharge

Hydrogen discharges driven by the combined radio-frequency(rf)/short pulse sources are investigated using the particle-in-cell method.The simulation results show that the discharge driven additionally by the short pulse can enhance the electron density and modulate the electron energy to provide a better condition for negative hydrogen ion production than the discharge driven by the rf-only source.     

基于北京大学4.5 MV静电加速器的核技术应用

北京大学4.5 MV静电加速器是20世纪80年代我国自主研发的静电加速器。该器端电压在0.7~3.8 MV连续可调,主要加速氢/氦同位素离子,并可通过打靶产生准单能直流/脉冲中子场,具有多条束线及多个实验终端。该器作为开放仪器多年来为国内外从事核技术研究的团队提供了实验平台。近年来,针对我国在能源、航天和国防等领域材料研究的重要需求,该器进行了多次升级改造。一方面通过产生7 MeV以下和14~19 MeV的准单能中子场,应用于(n, a)核反应截面的测量和聚变堆中子谱仪刻度;另一方面,通过温控辐照、核反应分析等实验终端,实现了材料辐照损伤及聚变堆材料元素定量分析等研究方向的功能拓展。此外,设计新增用于半导体材料电学性能测试的原位在线辐照终端和用于研究材料微观尺度元素分布的离子束综合分析实验终端。目前部分新终端已设计组装完成,相关搭建和调试工作正在进行中。     

Correlation Between Segmental Dynamics,Glass Transition,and Lithium Ion Conduction in Poly(Methyl Methacrylate)/Ionic Liquid Mixture

A solid-state membrane of a polymer/ionic liquid miscible mixture, poly(methyl methacrylate) (PMMA) and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF₆) doped with lithium perchlorate (LiClO₄), was prepared and characterized. Miscibility, segmental dynamics, glass transition and ionic conductivity were investigated. Based on the results from differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA), the system is fully miscible and of single phase. Broadening of the glass transition was observed when increasing the amount of ionic liquid, which can be attributed to mobility and flexibility differences between the polymer and ionic liquid. A large dynamical asymmetry and intrinsic mobility difference allow segmental and structural motion/relaxation over a wider temperature range by increasing the amount of ionic liquid. Saturation recovery spin–lattice relaxation time (T₁) versus temperature obtained from ⁷Li nuclear magnetic resonance (NMR) showed high mobility of lithium ions, which was almost temperature independent. Lithium ion conductivity significantly increases with increasing ionic liquid amount. It is concluded that lithium ion mobility and its conduction is positively correlated to segmental dynamics of ion carriers in this model system, which is more noticeable in mixtures with higher amounts of the ionic liquid.