Instruments of scientific visual representation in atomic databases

Graphic tools of spectral data representation provided by operating information systems on atomic spectroscopy—ASD NIST, VAMDC, SPECTR-W3, and Electronic Structure of Atoms—for the support of scientific-research and human-resource development are presented. Such tools of visual representation of scientific data as those of the spectrogram and Grotrian diagram plotting are considered. The possibility of comparative analysis of the experimentally obtained spectra and reference spectra of atomic systems formed according to the database of a resource is described. The access techniques to the mentioned graphic tools are presented.     

原子分子物理—研究宇宙物质的基础科学

艹勾清泉教授所从事、发展和传授的原子、分子结构理论在天体物理、天体化学、固体物理、材料科学以及极端条件物理的发展中起到基础理论的重要作用。他的研究群体活跃在各个相关的基础与应用领域里     

Euroball: Present status and outlook

Euroball is a European project to build a highly efficient and powerful gamma-ray spectrometer for nuclear structure spectroscopy. The project is an amalgamation of recent technical advances in detectors, electronics and data acquisition. In the first phase the spectrometer consists of 30 large single crystal Ge detectors, 26 Clover Ge detectors and 15 Cluster Ge detectors each with an associated suppression shield. The 239 individual Ge detector elements will have a total photopeak efficiency ∈ _p of ≈ 10% and will enable the properties of the atomic nucleus to be studied with a sensitivity up to or better than 10^?5 of the production cross-section. The elements of the spectrometer, including the detectors, the electronics and the data acquisition system, some of the planned ancillary detectors and the first results will be presented. Several developments are under investigation for the upgrade of Euroball for its second phase. These include an inner BGO ball for multiplicity and summed energy determination and inner particle detectors for charged particle identification. These developments will also be discussed.     

上海激光康普顿散射伽马源的发展和展望

激光康普顿散射(Laser Campton Scattering, LCS)光源,是一种基于相对论电子束与激光光子相互作用的新型X-ray或Gamma-ray光源。它具有能量高、波长短、脉冲快和峰值亮度高的特性,已成为国际先进光源技术的重要选项之一。本文介绍了激光康普顿散射光源的产生原理、国内外发展现状以及目前国际上运行和在建的激光康普顿散射光源装置,其中重点介绍了上海光源二期正在建设的上海激光电子伽马源(Shanghai Laser Electron Gamma Source, SLEGS)装置,以及在这一光源装置上可以开展的核物理、核天体物理、核废料处理及核医学应用等研究。随着上海软X射线自由电子激光试验装置(Soft X-ray Free Electron Laser, SXFEL)升级为用户装置,以及未来十三五国家重大科技基础设施-硬X射线自由电子装置(Shanghai HIgh repetition rate XFEL aNd Extreme light facility,SHINE)的建设完成,基于直线电子加速器(LINear ACcelator, LINAC)的康普顿散射光源的伽马能量将会达到GeV量级的高能量。超短脉冲、高极化度、高通量的激光康普顿散射光源将迎来新的发展机遇,基于康普顿伽马光源的核物理、天体物理、粒子物理及应用基础研究也必将迈上一个新台阶。     

用于火星电离层探测的星-星无线电掩星技术

火星和地球类似,周围束缚了不同密度的电离层.利用无线电掩星技术可以对火星电离层进行观测.星-地无线电掩星在探测精度和探测区域方面都受到一定的限制.中俄联合火星探测计划将于2011年10月一箭双星发射俄罗斯的Phobos-Grunt探测器和中国的萤火1号火星探测器.该计划将开展国际上首次火星电离层的星-星无线电掩星观测试验,重点是对星-地无线电掩星无法观测的正午和子夜区域的火星电离层进行探测.星-星无线电掩星观测试验采用双频工作模式,接收机灵敏度为-145dBm,相位测量精度优于5%周.在地面对接收机进行了动态模拟测试,测试得到的相位数据能很好地反演出火星电离层电子密度廓线.     

用于团簇碰撞研究的多路多道谱数据在线获取与处理系统

开发成功了基于ISA总线的智能高速AD数据采集接口电路。在一台PC微机中,可以同时使用多个该接口电路而不占用更多的PC机内存空间。在显示和处理数据时,数据采集速度不受影响。在Windows环境下开发成功了配套软件。用此接口电路构成了多路多道能谱数据获取与在线处理系统,并已成功地应用于微团簇与固体相互作用的实验研究中。     

PHELIX – Status and First Experiments

The high-energy high-power laser system PHELIX (Petawatt High Energy Laser for heavy Ion eXperiments) [1] is currently under construction at the Gesellschaft fuer Schwerionenforschung mbH (GSI) Darmstadt. With PHELIX GSI will offer the unique combination of a high-current, high-energy (GeV/u) heavy-ion beam with an intense laser beam. This will open the door to a variety of fundamental science issues in the field of atomic physics, plasma physics and nuclear physics. The project will gain further interest in the near future by the dramatic increase of the accelerator performance with the starting FAIR project at GSI [2]. This paper reports the current status of the project as well as the laser architecture. The proposed physics program and a first experiment carried out with PHELIX, the realization of a transient collisionally excited x-ray laser [3], will also be reviewed briefly.     

AJAC: Atomic data calculation tool in Python

In this work, new features and extensions of a currently used online atomic database management system are reported. A multiplatform flexible computation package is added to the present system, to allow the calculation of various atomic radiative and collisional processes, based on simplifying the use of some existing atomic codes adopted from the literature. The interaction between users and data is facilitated by a rather extensive Python graphical user interface working online and could be installed in personal computers of different classes. In particular, this study gives an overview of the use of one model of the package models (i.e., electron impact collisional excitation model). The accuracy of computing capability of the electron impact collisional excitation in the adopted model, which follows the distorted wave approximation approach, is enhanced by implementing the Dirac R-matrix approximation approach. The validity and utility of this approach are presented through a comparison of the current computed results with earlier available theoretical and experimental results. Finally, the source code is made available under the general public license and being distributed freely in the hope that it will be useful to a wide community of laboratory and astrophysical plasma diagnostics.     

Empirical photoabsorption cross sections for C,N, O,F and Cl obtained from molecular measurements between 50 and 340 Å

For many years, it has been known that many molecular photoabsorption cross sections in the hard X-ray region could be approximately obtained by summing the individual contributions of each atom to the total cross section. This article reports on an attempt to express 15 molecular cross sections as sums of empirical atomic cross sections for five constituent atoms C, N, O, F and Cl. For most wavelength ranges, the empirical atomic cross sections generated from a best fit to the molecular data were capable of describing the measured molecular cross sections to within 2% accuracy. In the 260–300 Å region where broad structures occur in the molecular spectra, the above model was slightly worse, perhaps indicating the appearance of molecular resonance effects discussed by other authors. It is suggested here that sums of empirical atomic cross sections will provide a useful means for prediction of molecular photoabsorption cross sections for molecules other than those investigated here for this limited wavelength region although it is acknowledge that the theoretical basis for this procedure is questionable.     

Quantum superchemistry: dynamical quantum effects in coupled atomic and molecular Bose-Einstein condensates

We show that in certain parameter regimes there is a macroscopic dynamical breakdown of the Gross-Pitaevskii equation. Stochastic field equations for coupled atomic and molecular condensates are derived using the functional positive- P representation. These equations describe the full quantum state of the coupled condensates and include the commonly used Gross-Pitaevskii equation as the noiseless limit. The full quantum theory includes the spontaneous processes which will become significant when the atomic population is low. The experimental signature of the quantum effects will be the time scale of the revival of the atomic population after a near total conversion to the molecular condensate.     

第五讲生物医学信息处理--DNA微阵列数据在医学中的应用

飞速发展的生物信息技术为现代医学提供了更为有效的工具．特别是随着人类基因组计划的基本完成和逐步细化，人们已经试图从基因水平上来认识生命现象，特别是一些重要疾病的机理．由于生物特性一般都涉及到多个基因的共同表达，这便出现了同时衡量成千上万个基因的表现水平的所谓DNA微阵列技术与数据．DNA微阵列数据也被称为大规模基因表达谱．根据这些微阵列数据，人们不仅能够对一些疾病进行分析，并且还能够发现一些新的生物特性与规律．另外，利用微阵列数据能够选取出疾病的相关基因并进行疾病的分类与诊断．这项研究无疑将推动医学的发展．最近，人们还进一步通过基因表达水平值来发现基因之间的调控方式，这将为疾病病理的研究与治疗提供更科学的依据．     

物理学和天文学

历史上，物理学和天文学的发展是密切联系的。它们在整个现代科学的发展和技术的发达上起到了先锋的作用。物理学的基本规律和天文学提供的广亵的实验室构成了理想的科学发展的基础。20世纪的一系列科学上的重要突破正是这种优良结合的产物。今天，天文学和物理学又共同面对着更新的前测问题，并一道酝酿着新的科学上的重大进展。它们所取得的每一个进展也必然伴随着技术的创新和提高，也不断更新着人类的认识和文明。     

Atomic and Molecular Data and their Applications

This topical issue on Atomic and molecular data and their applications was motivated by the 10th International Conference on Atomic and Molecular Data (ICAMDATA 2016), which was held from September 26 to 29, 2016 in Gunsan, Republic of Korea. The topics of this issue reflect those of the conference program. The scientific papers in the topical issue cover the fields of atomic and molecular structure, radiative transitions, scattering processes, data base development, and the applications of atomic and molecular data to plasma modeling.     

超重原子核与新元素研究

当前,原子核物理研究的一个重要前沿是探索原子核的电荷与质量极限,研究超重原子核与超重元素的性质,以及合成超重原子核。20世纪60年代,基于量子壳效应,理论预言质子数为114、中子数为184的原子核及其相邻核具有较长的寿命,甚至可能是稳定的,形成一个超重稳定岛。这个理论预言促进了重离子加速器及相关探测设备的建造,推动了重离子物理的发展。到目前,已经合成到了118号元素,填满了元素周期表的第7行。然而,合成更重的超重元素或包含更多中子的超重原子核面临着很多挑战,需要理论与实验密切结合,探索超重原子核的性质与合成机制,以登上超重稳定岛。文章概要评述超重原子核与新元素研究。首先介绍超重原子核与超重元素研究的背景及理论预言,包括超重核存在的根源、理论预言的概况等。之后简要给出实验合成超重核取得的主要进展和新元素命名情况。关于合成更重的超重元素面临的挑战,文章将针对利用重离子熔合蒸发反应合成超重核的截面低、所合成的超重核缺中子等情况展开讨论。最后评述近年来超重原子核结构性质、衰变、裂变与合成机制等方面的理论研究进展,包括超重核区的幻数和超重岛的位置,超重核的稳定性,利用重离子熔合蒸发反应合成超重核的三步过程及其复杂性,利用多核子转移合成超重核的探索,等等。The exploration of charge and mass limits of atomic nuclei and the synthesis of long-lived or stable superheavy nuclei (SHN) are at the frontier of modern nuclear physics. In the 1960s, based on the stability originating from quantum shell effects, the possible existence of an island of stability around 298114 was predicted. This prediction advanced the construction of heavy ion accelerators and detectors and the development of heavy ion physics. So far, superheavy elements (SHE) with Z up to 118 have been synthesized via heavy ion fusion reactions in laboratories. Recently the IUPAC/IUPAP Joint Working Party (JWP) concluded that criteria for the discovery of new elements have been met for those with Z=113, 115, 117 and 118. Therefore the seventh period of the periodic table of elements is completed. To synthesize even heavier elements or more neutron-rich SHN by using heavy ion fusion reactions, one confronts many challenges. More efforts should be made to study the properties of SHN both experimentally and theoretically. In this short review on the study on SHN and SHE, we will first introduce the background and theoretical predictions of SHN, including the origin of the possible existence of SHN and the predicted island of stability of SHN, etc. Then we will present progresses made up to now concerning the synthesis of SHN and the naming of the four new elements. As for the challenges nuclear physicists confront in synthesizing even heavier SHEs, we will detail those connected with heavy ion fusion-evaporation reactions, namely, the tiny cross sections to produce SHN and the fact that only neutron-deficient SHNs can be synthesized. Finally we will discuss some theoretical progresses on the study of SHN, including the structure of SHN and proton and neutron magic numbers after 208Pb, the stability and the synthesis mechanism of SHN as well as what we should focus on in the future.     

Processes of DNA condensation induced by multivalent cations： Approximate annealing experiments and molecular dynamics simulations

The condensation of DNA induced by spermine is studied by atomic force microscopy （AFM） and molecular dynamics （MD） simulation in this paper. In our experiments, an equivalent amount of multivalent cations is added to the DNA solutions in different numbers of steps, and we find that the process of DNA condensation strongly depends on the speed of adding cations. That is, the slower the spermine cations are added, the slower the DNA aggregates. The MD and steered molecular dynamics （SMD） simulation results agree well with the experimental results, and the simulation data also show that the more steps of adding multivalent cations there are, the more compact the condensed DNA structure will be. This investigation can help us to control DNA condensation and understand the complicated structures of DNA--cation complexes.     

《大学物理实验数据检验及存储系统》软件设计

利用ASP设计了网上交互式物理实验数据检验与存储系统.学生可以利用本系统自行检验实验数据含仪器读数的正确性;实验数据提交到数据库中存储,以备事后进行数据处理及教师批改实验报告之用.     

Anharmonic Potential Functions in Polyatomic Molecules as Derived from Their Vibrational and Rotational Spectra

It is well known that the anharmonic part of the molecular potential function contributes to the vibration-rotation energy and to the apparent molecular geometry, although the anharmonic effect is not so profound as that from its harmonic counterpart. Nevertheless, it cannot simply be ignored for the precise treatment of molecular dynamics and structures. For a better understanding of the molecular potential function, it is highly desirable to extend the force constant calculation to evaluate the terms beyond quadratic, which will give a more realistic potential map of polyatomic molecules for wider ranges of atomic displacements. The vibrational anharmonicity also affects the transition intensities through the mixing vibration-rotation wave functions.     

由东南亚海啸引发的一堂物理课

印度洋海啸被认为是一次“全球性地球物理学事件”．通过对“海啸的物理学”的教学设计,利用从互联网收集的最新资料,结合学生的物理知识,对海啸中的物理现象作了计算和分析．     

量子遂穿在双阱异核分子形成过程中的作用(英文）

对于束缚在双阱中的两组分玻色－爱因斯坦凝聚体,本文研究了基于光缔合机制形成分子的过程中,量子隧穿所起的作用．该双阱外势可以在实验上利用磁场生成的谐振子势和由蓝失谐光或射频源生成的中心势垒来实现．在合适的光场中,我们分析了系统在不同初始状态下的短时极限量子动力学,同时对系统做了在平均场近似下的数值计算分析．我们发现无论是隧穿强度还是初始状态的制备都对系统的动力学有很大的影响．我们还计算了同核分子在这些情况下的结果,并和异核分子计算的结果作了比较．量子化的光缔合光场在分子形成过程的影响也在文章中给予了讨论．     

Sub-Doppler laser spectroscopy

Ideal primary data in atomic and molecular physics would include the energy levels of single isolated atoms and molecules, and an approximation to these is obtained from spectra of gases at low pressures. In classical spectroscopy a severe barrier to spectral resolution and measurement precision is often encountered because of the Doppler effect. The absorption frequency of an atom or molecule is modified by its velocity, and so a spectral line will be broadened because of the thermal distribution of velocities in a gas. The barrier can, however, be overcome by using lasers in a variety of different ways. This article introduces the two primary techniques now employed, namely Lamb dip and two-photon spectroscopy, and a variety of examples are discussed. Alternative strategies employing molecular beams, laser cooling and time resolution are also outlined. Limitations on extreme resolution are considered, and the article concludes with a section on laser frequency stabilization and frequency standards which often rely on sub-Doppler spectra.