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On the knee of Galactic cosmic rays in light of sub-TeV spectral hardenings

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Chinese Physics C 2018年第7期42卷 113-122页

作者： Yi-Qing Guo1.2.Qiang Yuan1.3 1. Key {1. of Dark Matter and Space astronomy Purple Mountain Observatory Chinese {2. of Sciences nanjing 2.0008 china 2. Key {1. of Particle Astrophysics Institute of High Energy Physics Key laboratory of Dark Matter and Space {1. Purple Mountain ObservatoryChinese Academy of Sciences Key laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of Sciences School of astronomy and Space Science University of Science and Technology of China

More than fifty years after the discovery of the knee in the cosmic ray （CR） spectra, its physical origin remains a mystery. This is partly due to the ambiguity of the energy spectra of individual components. Recently, direct measurements from several space experiments found significant spectral hardenings of CR nuclei at ~2.0 GV. A {1. modeling of the direct and indirect measurements may help to understand the experimental systematics and the physics of the knee. In this work, we update the phenomenological ＂poly-gonato＂ model to include the spectral hardenings, with a changing spectral index of γ ＋ β·logE. This modification gives a reasonable description of the CR spectra in a wide energy range. However, the fits to different data sets give different results. We find that the fit to the AMS-02.and CREAM data slightly favors a relatively low energy knee of the light components. In such a case, the expected all-particle spectra under-shoot the data, which may require an extra component of CRs. The fits to AMS-02.data and the light component （H＋He） data from the Tibet ASγ/ARGO-YBJ/WFCTA and KASCADE experiments give consistent results with the all-particle spectra. We further propose a possible physical realization of such a ＂modified poly-gonato＂ model of spectral hardenings by means of spatially-dependent diffusion of CRs. We find reasonably good agreement between the model predictions and the data for CR spectra, the secondary-to-primary ratios, and the amplitude of anisotropies.

关键词： cosmic ray knee spectrum propagation

Large-scale boron nanowire nanojunctions and their highly-oriented arrays

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Science china(Physics,Mechanics & {1.) 2004年第5期47卷 621-632页

作者： CAO Limin1.2. ZHANG Ze2.& WANG Wenkui1.2.1. Key laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, china 2. Institute of Physics, Chinese {2. of Sciences, Beijing 1.0080, china 1. Key laboratory of Metastable Materials Science and Technology Yanshan University 066004 Qinhuangdao China 2. Institute of Physics Chinese Academy of Sciences 100080 Beijing China

Highly oriented multiple boron nanowire nanojunctions with unilateral feather- like morphology were first successfully prepared using a radio-frequency magnetron sputtering method. The branched boron nano-feathers always nucleate and grow on the same sidewall of the stems, and align in parallel to form multiple T- and/or Y-type nanojunctions. The diameters of the branches and the stems are in the range of 2.—40 and 60—80 nm, respectively. The thinner branches and thicker stems of the boron nanowires self-assembled into large-scale, highly ordered arrays on various substrates. During the formation and self-assembly of the arrays, no template or catalyst was needed. We believe that the approach presented here can be used to fabricate heterostructures with bottom-up assembly of a wide variety of one-dimensional nanostructures via the rational design of targets and the proper control of the experimental conditions.

关键词： boron nanowires, nanojunctions, self-assembly, magnetron sputtering.

Gasdynamic characteristics of toroidal shock and detonation wave converging

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Science china(Physics,Mechanics & {1.) 2005年第6期48卷 739-749页

作者： TENG Honghui1.2.& JIANG Zonglin2.1. Key laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese academy of Sci- ences, Beijing 1.0080,{2. 2. Graduate University of Chinese academy of Sciences, Beijing 1.0039,{2. 1. Key laboratory of High Temperature Gas Dynamics Institute of Mechanics Chinese Academy of Sciences 100080 Beijing China 2. Graduate University of Chinese {1. of Sciences 100039 Beijing China

The modified CCW relation is applied to analyzing the shock, detonation wave converging and the role of chemical reactions in the process. Results indicate that the shock wave is strengthened faster than the detonation wave in the converging at the same initial Mach number. Euler equations implemented with a detailed chemical reaction model are solved to simulate toroidal shock and detonation wave converging. Gasdynamic characteristics of the converging are investigated, including wave interaction patterns, observable discrepancies and physical phenomena behind them. By comparing wave diffractions, converging processes and pressure evolutions in the focusing area, the different effects of chemical reactions on diffracting and converging processes are discussed and the analytic conclusion is demonstrated through the observation of numerical simulations.

关键词： converging, CCW relation, shock wave, detonation wave.

Development of superconducting mixers for THz astronomy

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Science china(Information Sciences) 2012年第1期55卷 120-126页

作者： SHI ShengCai1.2.1.urple Mountain Observatory,Chinese {1. of Sciences,nanjing {2.,china 2.ey laboratory of Radio astronomy,Chinese {1. of Sciences,nanjing {2.,china 1. Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China2. Key Laboratory of Radio Astronomy Chinese Academy of Sciences Nanjing 210008 China

The terahertz(THz)regime,loosely defined as 0.1.1. THz,is the last frequency window to be fully explored in *** particular,it is a regime in which there are rich molecular rotation lines and atomic fine structure *** are very important tracers for studying the dynamics of astronomical objects such as stars and planetary *** those spectral lines usually makes use of coherent detectors(i.e.,heterodyne mixers).With sensitivity approaching the quantum limit,superconducting mixers have become the coherent detector of choice in THz *** this paper we mainly introduce the superconducting mixers developed at Purple Mountain Observatory and those for international collaborative projects.

关键词： terahertz detection superconducting mixer quantum limit

Magnetron sputtering synthesis of large area well-ordered boron nanowire arrays

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Science china(Physics,Mechanics & {1.) 2004年第4期47卷 403-415页

作者： CAO Limin1.2. ZHANG Ze2.& WANG Wenkui1.2.1. Key laboratory of Metastable Materials Science and Technology and College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004, china 2. Institute of Physics, Chinese {2. of Sciences, Beijing 1.0080, china 1. Key laboratory of Metastable Materials Science and Technology and College of Materials Science and Engineering Yanshan University 066004 Qinhuangdao China 2. Institute of Physics Chinese Academy of Sciences 100080 Beijing China

One-dimensionally nanostructured materials, such as nanowires and nanotubes, are the smallest dimensional structures for efficient transport of electrons and excitons, and are therefore critical building blocks for nanoscale electronic and mechanical devices. In this paper, boron nanowires with uniform diameters from 2. to 80 nm were synthesized by radio-frequency magnetron sputtering of pure boron powder and B2.3 powder mixtures in argon atmosphere. The boron nanowires produced stand vertically on the substrate surface to form well-ordered arrays over large areas with self- organized arrangements without involvement of any template and patterned catalyst. The high-density boron nanowires are parallel to each other and well distributed, forming highly ordered and uniform arrays. A more interesting and unique feature of the boron nanowires is that most of their tips are flat rather than hemispherical in morphologies. Detailed studies on its structure and composition indicate that boron nanowires are amorphous. Boron nanowire appears as a new member in the family of one-dimensional nanostructures. Considering the unique properties of boron-rich solids and other nanostructures, it is reasonable to expect that the boron nanowires will display some exceptional and interesting properties. A vapor-cluster-solid (VCS) mechanism was proposed to explain the growth of boron nanowires based on our experimental observations.

关键词： boron nanowires, magnetron sputtering, arrays, self-assembly.

Recent progress of solar physics research in china

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Research in astronomy and Astrophysics 2011年第12期11卷 1377-1402页

作者： Cheng Fang 1.School of astronomy and Space Science,{1. University,{1. 2.0093,china 2.Key laboratory of Modern astronomy and Astrophysics({1. University),Ministry of Education,china School of astronomy and Space Science Nanjing University Nanjing 210093 China Key laboratory of Modern {1. and Astrophysics ({2. University) Ministry of Education China

Owing to the largely improved facilities and working conditions, solar physics research in china has recently shown marked development. This paper reports on the recent progress of solar physics research in china's Mainland, mainly focusing on several hot issues, including instrumentations, magnetic field observations and research, solar flares, filaments and their eruptions, coronal mass ejections and related processes, as well as active regions and the corona, small-scale phenomena, solar activity and its predictions. A vision of the future is also described.

关键词： Sun: general -- Sun: coronal mass ejections (CMEs) -- solar physics:recent progress

Wet-chemical synthesis and characteristics of Au nanoshell

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Science china Chemistry 2005年第5期48卷 431-435页

作者： LIU Zhongxin1.2. SONG Hongwei1. YU Lixin1.2. YANG Linmei1.2.& PAN Guohui1.2.1. Key laboratory of Excited State Physics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese academy of Sciences, Changchun 1.0033,{2. 2. Graduate School of the Chinese academy of Sciences, Beijing 1.0039,{2. 1. Key laboratory of Excited State Physics Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences 130033 Changchun China 2. Graduate School of the Chinese {1. of Sciences 100039 Beijing China

Gold nanoshells were prepared by an easy wet-chemical method, with Ag nanoparticles used as the templates. Transmission electron microscopy (TEM) indicated that the shells were sphere in shape, the size was homogenous, being about 2. nm, and no hard ag-glomerates were observed. The plasma resonance absorption of gold was tuned from visible to near-infrared (NIR) with the increased volume of HAuCl4. The temperature grads (?T) of the gold nanoshell hydrosol under the exposure of an 808-nm {1. fiber laser with different power den-sities were measured. The highest ?T was 30℃ (5 W/cm2. irradiation area was 2.cm2.. This kind of gold nanoshell hydrosol is a promising material to be used in biomedicine such as photo-thermal cancer therapy, and its special photothermal convert property will photothermally trigger drug release.

关键词： wet-chemical synthesis, Au, nanoshell, NIR absorption, photothermal conversion.

Grain evolution of nano-crystals ZnO under HP and HT

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Science china(Physics,Mechanics & {1.) 2006年第3期49卷 281-290页

作者： SHAO Guangjie1. QIN Xiujuan1. LIU Riping1. WANG Wenkui1.2.& YAO Yushu2.1. Key laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, china 2. Institute of Physics, Chinese {2. of Sciences, Beijing 1.0080, china 1. Key laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao 066004 China 2. Institute of Physics Chinese Academy of Sciences Beijing 100080 China

Grain evolution of nano-crystals ZnO under high temperature and pressure is studied using a cubic high pressure apparatus. The structure, grain sizes and morphology of the samples are characterized by X-ray diffraction and field emission scanning electron microscopy. The results show that the grain sizes of ZnO grow rapidly at temperature 2.0℃ under pressure. At temperature lower than 300 ℃ (including 300 ℃), the grain sizes of the samples first increase with the pressure increasing from 1.to 3 GPa and later de- crease from 4 to 6 GPa. The activation volume from 1.to 3 GPa and from 4 to 6 GPa is calculated respectively using the phenomenological kinetic grain growth equation at temperature 300 ℃. At temperature higher than 400℃ (including 400 ℃), the grain sizes of the samples increase with the pressure increasing from 1.to 6 GPa. ZnO nano-bulks with good quality can be obtained under the specific conditions.

关键词： nano-crystals ZnO,high temperature and pressure,grain evolution

A study of constraints on the constitutive relationships of electromagnetic medium based on generally acknowledged truths

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Science china(Physics,Mechanics & {1.) 2005年第5期48卷 541-548页

作者： GUO Huiping1. LIU Xueguan1.2. YIN Hongcheng2. CHAO Zengming2.& HUANG Peikang2.1. School of Electronics and Information Engineering, Soochow University, Suzhou 2.502., china 2. National Electromagnetic Scattering laboratory, Beijing 1.0854, china 1. School of Electronics and Information Engineering Soochow University 215021 Suzhou China 2. National Electromagnetic Scattering {1. 100854 Beijing China

The study of constraints on the constitutive relationships of electromagnetic media is of great importance in the aspects of the medium characteristics analysis, the new article material synthesis and the medium parameters reconstruction, etc. According to the fact that the constitutive relationships should not conflict with the general physical laws, the constraints that the constitutive relationships of electromagnetic medium must satisfy have been summarized in this paper. These constraints include determinacy principle, objectivity principle, causality principle and permission principle. And the parameter constraints of the arbitrary linear homogenous time-invariant medium are obtained following the minimum energy consumption principle. This work provides a new way of ascertaining the constitutive relationships of the electromagnetic medium.

关键词： electromagnetic medium, medium parameter constraint, generally acknowledged truths, energy conservation principle, minimum energy consumption principle.