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Fermi/LAT observations of lobe-dominant radio galaxy 3C 207 and possible radiation region of γ-rays

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Research in Astronomy and Astrophysics 2018年第6期18卷 93-98页

作者： Sheng-Chu Guo Hai-Ming Zhang Jin Zhang En-Wei Liang Guangxi key laboratory for Relativistic Astrophysics Department of Physics Guangxi University key laboratory of Space Astronomy and Technology National Astronomical Observatories Chinese Academy of Sciences

3 C 207 is a lobe-dominant radio galaxy with a one sided jet and bright knots, spanning a kpcMpc scale, which have been resolved in the radio, optical and X-ray bands. This target was confirmed as a γ-ray emitter with Fermi/LAT, but it is uncertain whether the γ-ray emission region is the core or knots due to the low spatial resolution of Fermi/LAT. We present an analysis of its Fermi/LAT data acquired during the past 9 years. Different from the radio and optical emission from the core, it is found that theγ-ray emission is steady without detection of flux variation at over a 2σ confidence level. This likely implies that the γ-ray emission is from its knots. We collect the radio, optical and X-ray data of knot-A,the closest knot from the core at 1.4′′, and compile its spectral energy distribution(SED). Although the single-zone synchrotron+SSC+IC/CMB model that assumes knot-A is at rest can reproduce the SED in the radio-optical-X-ray band, the predicted γ-ray flux is lower than the LAT observations and the derived magnetic field strength deviates from the equipartition condition by 3 orders of magnitude. Assuming that knot-A is moving relativistically, its SED from radio to γ-ray bands would be represented well with the single-zone synchrotron+SSC+IC/CMB model under the equipartition condition. These results likely suggest that the γ-ray emission may be from knot-A via the IC/CMB process and the knot should have relativistical motion. The jet power derived from our model parameters is also roughly consistent with the kinetic power estimated with radio data.

关键词： galaxies: active galaxies: jets radiation mechanisms: non-thermal galaxies: individual(3C 207)

Prospective study on observations of γ-ray sources in the Galaxy using the HADAR experiment

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Frontiers of physics 2022年第6期17卷 1-14页

作者： Xiangli Qian Huiying Sun Tianlu Chen Danzengluobu Youliang Feng Qi Gao Quanbu Gou Yiqing Guo Hongbo Hu Mingming Kang Haijin Li Cheng Liu Maoyuan Liu Wei Liu Bingqiang Qiao Xu Wang Zhen Wang Guangguang Xin Yuhua Yao Qiang Yuan Yi Zhang School of Intelligent Engineering Shandong Management UniversityJinan 250357China The key laboratory of Cosmic rays(Tibet University) Ministry of EducationLhasa 850000China key laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences 19 A Yuquan RoadShijingshan DistrictBeijing 100049China College of Physics Sichuan UniversityChengdu 610064China Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China School of Physics and Technology Wuhan UniversityWuhan 430072China key laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210008China

The High Altitude Detection of Astronomical Radiation(HADAR)experiment is a refracting terrestrial telescope array based on the atmospheric Cherenkov imaging *** focuses the Cherenkov light emitted by extensive air showers through a large aperture water-lens system for observing very-high-energyγ-rays and cosmic *** the advantages of a large field-of-view(FOV)and low energy threshold,the HADAR experiment operates in a large-scale sky scanning mode to observe galactic *** study presents the prospects of using the HADAR experiment for the sky survey of TeVγ-ray sources from TeVCat and provids a one-year survey of statistical *** from the simulation show that a total of 23 galactic point sources,including five supernova remnant sources and superbubbles,four pulsar wind nebula sources,and 14 unidentified sources,were detected in the HADAR FOV with a significance greater than 5 standard deviations(σ).The statistical significance for the Crab Nebula during one year of operation reached 346.0σand the one-year integral sensitivity of HADAR above 1 TeV was~1.3%–2.4%of the flux from the Crab Nebula.

关键词： HADAR Galactic sources significance gamma rays

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X-ray-boosted photoionization for the measurement of an intense laser pulse

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Chinese Physics B 2013年第6期22卷 322-329页

作者：葛愉成何海萍 School of Physics and State key laboratory of Nuclear Physics and Technology Peking University

Investigations show that X-ray-boosted photoionization （XBP） has the following advantages for in-situ measurements of ultrahigh laser intensity 1 and field envelope F（t）（time t, pulse duration VL, carrier-envelope-phase Ф）： accuracy, dynamic range, and rapidness. The calculated XBP spectra resemble inversely proportional functions of the photoelectron momentum shift. The maximum momentum p and the observable value Q （defined as a double integration of a normalized photoelectron energy spectrum, PES） linearly depend on I^1/2 and τL, respectively. Ф and F（t） can be determined from the PES cut-off energy and peak positions. The measurable laser intensity can be up to and over 1018 W/cm2 by using high energy X-rays and highly charged inert gases.

关键词： measurement of ultrahigh laser pulse X-ray-boosted photoionization photoelectron energy spectrum quantum interference

Investigation on X-Radiation for 126 kV Vacuum Interrupters

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Plasma Science and Technology 2016年第5期18卷 577-582页

作者：闫静刘志远耿英三张胜张颖瑶 State key laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University

When subjected to high voltages between opened contacts, vacuum interrupters may emit X-rays. In order to ensure that these are of an acceptable level, vacuum interrupters should comply with the limits for X-ray emission and the test procedures to be carried out to verify this based on relevant standards and specifications. In this paper, a comprehensive experimental study has been performed for 126 kV vacuum interrupters used in a transmission system to understand the X-radiation level and its influence by three main parameters, namely applied power-frequency voltage, contact gap and power=frequency voltage conditioning. The radiation instrument is an FJ347 radiometer and the X-radiation dose was measured at the power-frequency test voltage. These tests demonstrated that the X-radiation emission level for a 126 kV vacuum interrupter did not exceed the following： 5 μSv per hour at a rated voltage of 126 kV and 150 μSv per hour at a power-frequency voltage of 230 kV at 1 m distance. The X-radiation dose increased with the applied power-frequency voltage increasing and decreased with the contact gap increasing. The X- radiation dose for 126 kV vacuum interrupters decreased by 57% after the conditioning procedure with a certain power-frequency voltage. During the conditioning procedure, the average value of the X-radiation dose was 4.49 mSv, which means if a professional conditions 180 interrupters per year, it will be safe at the 6.4 m distance.

关键词： vacuum interrupter X-radiation power-frequency voltage contact gap volt-age conditioning

Two New r-process-enhanced Stars with [Fe/H] >-0.6 dex from the LAMOST-MRS Survey

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Research in Astronomy and Astrophysics 2022年第7期22卷 109-117页

作者： Xiao-Jin Xie Jian-Rong Shi Tian-Lu Chen Hong-Liang Yan Tian-Yi Chen Kai-Ke Pan Chun-Qian Li Shuai Liu Qi Gao Tai-Sheng Yan Ming-Yi Ding Department of Physics College of ScienceTibet UniversityLhasa 850000China key laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China key laboratory of Cosmic rays(Tibet University) Ministry of EducationLhasa 850000China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Apache Point Observatory SunspotNew Mexico 88349USA Astronomy Department New Mexico State UniversityLas CrucesNew Mexico 88003USA

We report the discovery of two r-process-enhanced stars with [Fe/H]>-0.6 dex selected from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST) *** candidate stars have been selected from the LAMOST medium-resolution(R~ 7500) spectroscopic survey,and the follo wed-up high signal-to-noise ratio and high-resolution(R~31,500) spectra are obtained with the ARC Echelle Spectrograph mounted on the3.5 m telescope at the Apache Point Observatory,which allow us for the determination of stellar atmospheric parameters and abundances of 20 *** these three r-process-enhanced candidate stars,TYC 1710-933-1 and TYC 2858-372-1 have [Eu/Fe] higher than 0.3 dex and [Ba/Eu] lower than 0.0 dex,thus,can be identified as new r-process-enhanced *** 2858-372-1 shows similar r+s-process pattern to the *** 1710-933-1 presents enhancement of the r-process elements of Nd and *** work indicates that the enrichment mechanisms of the heavy neutron-capture elements are complicated for metal-rich stars.

关键词： stars:abundances stars:chemically peculiar stars:fundamental parameters

Dispersion stabilization of antimony-doped tin oxide(ATO)nanoparticles used for energy-efficient glass coating

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Particuology 2014年第6期12卷 49-53页

作者： Ning Li Qinglin Meng Nan Zhang State key laboratory of Subtropical Building Science Building Environment Energy Laboratory(BEEL)South China University of Technology

Nano-antimony-doped tin oxide（ATO） was synthesized using the sol-gel method.A colloidal dispersion of ATO nanoparticles in distilled water was achieved using a milling process in which different dispersants were *** this paper,different factors that affect the stability of ATO nanoparticles were discussed,such as zeta potential,dispersant,and pH *** polyphosphate was a suitable dispersant for stabilizing ATO nanoparticles in distilled water.A stable dispersion of ATO nanoparticles in distilled water was *** stable dispersion of ATO nanoparticles was used to prepare nano-thermal insulation glass paint to block near-infrared rays of sunlight.

关键词： Nano-ATO dispersion Zeta potential Stabilization Energy-efficient glass coating

Geometric matrix research for nuclear waste drum tomographic gamma scanning transmission image reconstruction

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Chinese Physics C 2015年第6期39卷 116-120页

作者：张金钊庹先国 Applied Nuclear Techniques in Geoscience key laboratory Chengdu University of Technology State key laboratory of Geohazard Prevention & Geoenvironmental Protection Southwest University of Science and Technology

A geometric matrix model of nuclear waste drums is proposed for transmission image reconstruction from tomographic gamma scans（TGS）. The model assumes that rays are conical, with intensity uniformly distributed within the cone. The attenuation coefficients are centered on the voxel（cube） of the geometric center. The proposed model is verified using the EM algorithm and compared to previously reported models. The calculated results show that the model can obtain good reconstruction results even when the sample models are highly heterogeneous.

关键词： tomographic verified cube reconstructed attenuation uniformly heterogeneous gamma projection uncertainty

Laser-produced plasma He-alpha source for pulse radiography

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Chinese Optics Letters 2009年第2期7卷 156-158页

作者：王瑞荣陈伟民毛楚生董佳钦傅思祖 The key laboratory of Optoelectronic Technology and System Ministry of EducationChongqing University State key laboratory of High Power Laser and Physics Shanghai Institute of Laser PlasmaChina Academy of Engineering Physics

Through the use of time and space integrated kiloelectronvolt （keV） spectroscopy, we investigate the thermal emission of plasma, which produces strong line emission from the titanium K shell （He-a at 4.7 keV and H-α at 4.9 keV）, created by laser. In order to optimize the conversion efficiency enhancement on titanium foils, the experiment is conducted under a variety of laser-driven intensity conditions. The X-ray emission intensity at 4.7 keV is measured and compared with prediction. The experimental result demonstrates that the solid Ti target laser-produced plasma （LPP） source has X-ray emission at 4.7 keV, which are all generated from electronic transitions in Ti ions at pulse width of 2.1 ns or 30 ps, the crudely evaluated He-α X-ray intensity appears to slightly increase with laser intensity enhancement, and the pre- pulse effect increases the conversion efficiency of the He-α X-ray. In addition, a 90-μm-thick Ti foil as a filter is used to transmit He-α X-ray at near 4.7 keV, creating a quasi-monochromatic transmission and greatly reducing the lower- and higher-energy background.

关键词： Conversion efficiency Electromagnetic wave emission Emission spectroscopy Helium Ion beams Laser produced plasmas Lasers Plasma diagnostics Titanium X ray radiography X ray scattering X rays

Use of photoelectron laser phase determination method for attosecond measurements with quantum-mechanical calculations

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Chinese Physics B 2008年第6期17卷 2072-2077页

作者：葛愉成 Department of Technical Physics and DOE key laboratory of Heavy Ion Physics Peking University

This paper calculates quantum-mechanically the photoelectron energy spectra excited by attosecond x-rays in the presence of a few-cycle laser. A photoelectron laser phase determination method is used for precise measurements of the pulse natural properties of x-ray intensity and the instantaneous frequency profiles. As a direct procedure without any previous pulse profile assumptions and time-resolved measurements as well as data fitting analysis, this method can be used to improve the time resolutions of attosecond timing and measurements with metrological precision. The measurement range is half of a laser optical cycle.

关键词： attosecond measurement photoelectron spectrum laser phase determination transfer equation