• Title/Summary/Keyword: Synchrotron

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Recent SAXS Progress at NSRRC

  • Jeng U.;Hsu C.-H.;Sun Y.-S.;Lai Y.-H.;Chung W.-T.;Sheu H.-S.;Lee H.-Y.;Song Y.-F.;Liang K. S.;Lin T.-L.
    • Macromolecular Research
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    • v.13 no.6
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    • pp.506-513
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    • 2005
  • We review the recent SAXS activity on the 1.5-GeV electron storage ring at the National Synchrotron Radiation Research Center (NSRRC). Typical measurements featuring in grazing incident SAXS for soft materials are illustrated. Complex measurements using simultaneous SAXS/DSC and SAXSIWAXS for the correlations between the crystallization and mesoscale ordering in a polymer blend and a polypeptide-block-polypseudorotaxane diblock copolymer are presented. We also introduce a dedicated SAXS beamline which is planned at NSRRC.

Statistical study of turbulence from polarized synchrotron emission

  • Lee, Hyeseung;Cho, Chungyeon;Lazarian, Alexandre
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.1
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    • pp.56.1-56.1
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    • 2017
  • When turbulent motions perturb magnetic field lines and produce magnetic fluctuations, the perturbations leave imprints of turbulence statistics on magnetic field. Observation of synchrotron radiation is one of the easiest ways to study turbulent magnetic field. Therefore, we study statistical properties of synchrotron polarization emitted from media with magnetohydrodynamic (MHD) turbulence, using both synthetic and MHD turbulence simulation data. First, we obtain the spatial spectrum and its derivative with respect to wavelength of synchrotron polarization arising from both synchrotron radiation and Faraday rotation. The study of spatial spectrum shows how the spectrum is affected by Faraday rotation and how we can recover the statistics of underlying turbulent magnetic field as well as turbulent density of electrons from interferometric observations that incorporate the effects of noise and finite telescopic beam size. Second, we study quadrupole ratio to quantitatively describe the degree of anisotropy introduced by magnetic field in the presence of MHD turbulence. We consider the case that the synchrotron emission and Faraday rotation are spatially separated, as well as the situation that the sources of the synchrotron radiation and thermal electrons causing Faraday rotation exist in the same region. In this study, we demonstrate that the spectrum and quadrupole ratio of synchrotron polarization can be very informative tools to get detailed information about the statistical properties of MHD turbulence from radio observations of diffuse synchrotron polarization.

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Study of synchrotron photons by the Prototype Synchrotron Radiation Detector in the space

  • Park, Wung-Hoa;Lee, Man-Woo;Kim, Kyung-Suk;Kim, Guin-Yun;Yang, Jong-Man;Son, Dong-Chul
    • Bulletin of the Korean Space Science Society
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    • 2008.10a
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    • pp.23.1-23.1
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    • 2008
  • A space shuttle with a Prototype Synchrotron Radiation Detector (PSRD) was launched in 2001. PSRD was set in the Endeavour payloads and got data for 12 days. The purpose of PSRD is to measure synchrotron photons which are created by high energy charged particles near earth. Synchrotron photons are confused with background photons. We studied how to separate synchrotron photons from backgrounds.

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Study of Magnetohydrodynamic Turbulence Using Multi-frequency Synchrotron Polarization Observations

  • Lee, Hyeseung;Cho, Jungyeon;Lazarian, Alex
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.44.2-44.2
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    • 2019
  • Turbulent motions perturb magnetic field lines and produce magnetic fluctuations. The perturbations leave imprints of turbulence statistics on magnetic field. Observation of synchrotron radiation is one of the easiest ways to study turbulent magnetic field. First, we obtained the spatial spectrum of synchrotron polarization so that shows how the spectrum is affected by Faraday rotation and how to recover the statistics of underlying turbulence magnetic field. Since polarized synchrotron intensity arising from magnetized turbulence are anisotropic along the direction of mean magnetic field. Secondly, we studied quadrupole ratio to quantitatively describe the degree of anisotropy introduced by magnetic field at multi-wavelengths. This work demonstrated that the spectrum and quadrupole ratio of synchrotron polarization can be very informative tools to get detailed information about the statistical properties of MHD turbulence from radio observations of diffuse synchrotron polarization.

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The Spectral Sharpness Angle of Gamma-ray Bursts

  • Yu, Hoi-Fung;van Eerten, Hendrik J.;Greiner, Jochen;Sari, Re'em;Bhat, P. Narayana;Kienlin, Andreas von;Paciesas, William S.;Preece, Robert D.
    • Journal of Astronomy and Space Sciences
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    • v.33 no.2
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    • pp.109-117
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    • 2016
  • We explain the results of Yu et al. (2015b) of the novel sharpness angle measurement to a large number of spectra obtained from the Fermi gamma-ray burst monitor. The sharpness angle is compared to the values obtained from various representative emission models: blackbody, single-electron synchrotron, synchrotron emission from a Maxwellian or power-law electron distribution. It is found that more than 91% of the high temporally and spectrally resolved spectra are inconsistent with any kind of optically thin synchrotron emission model alone. It is also found that the limiting case, a single temperature Maxwellian synchrotron function, can only contribute up to 58+23−18% of the peak flux. These results show that even the sharpest but non-realistic case, the single-electron synchrotron function, cannot explain a large fraction of the observed spectra. Since any combination of physically possible synchrotron spectra added together will always further broaden the spectrum, emission mechanisms other than optically thin synchrotron radiation are likely required in a full explanation of the spectral peaks or breaks of the GRB prompt emission phase.

Temperature Dependent Octahedral Tilting Behaviors of Monoclinic and Tetragonal SrRuO3 Thin Films

  • Lee, Sung Su;Seo, Okkyun;Kim, Jaemyung;Song, Chulho;Hiroi, Satoshi;Chen, Yanna;Katsuya, Yoshio;Sakata, Osami
    • Journal of the Korean Physical Society
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    • v.73 no.10
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    • pp.1529-1534
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    • 2018
  • We used in-situ synchrotron X-ray scattering to investigate phase transformations of octahedral tilted monoclinic $SrRuO_3$ (MSRO) and tetragonal SRO (TSRO) thin films on $SrTiO_3$ (STO) substrates. The octahedral tilted MSRO thin films were highly crystalline and the monoclinic distortion angle was $0.45^{\circ}$. The phase transition temperature from the MSRO to TSRO phase occurred at approximately $200^{\circ}C$ as a second order transition. Conversely, no phase transformations of the TSRO thin film occurred within the range from RT to $250^{\circ}C$. The octahedral $RuO_6$ rotation was strongly affected by the phase transformation in the SRO thin films.

In Situ Observation of Initial Rusting Process of Steel Containing Al Using Synchrotron Radiation X-Rays

  • Morimoto, J.;Yamashita, M.;Uchida, H.;Doi, T.;Kamimura, T.;Miyuki, H.;Konishi, H.;Mizuki, J.
    • Corrosion Science and Technology
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    • v.7 no.2
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    • pp.112-118
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    • 2008
  • We observed initial rusting process of steel containing Al under wet/dry cyclic condition with NaCl solution film using in situ X-ray diffraction spectroscopy at SPring-8 synchrotron radiation facility. It was found that mass fraction of iron oxides such as ${\alpha}-FeOOH$, ${\beta}-FeOOH$ and ${\gamma}-FeOOH$ varied with Al content. Some kinds of Al oxides were also found at the initial stage of corrosion. Those corrosion products might affect the corrosion process and corrosion rate of the steel.

Manufacturing of Micromolds for Plastic Molding Technologies via Synchrotron LIGA Process (방사광 LIGA 공정을 이용한 플라스틱 성형용 마이크로 금형 제작)

  • Lee, Bong-Kee;Kim, Jong-Hyun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.14 no.4
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    • pp.1-7
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    • 2015
  • In the present study, copper micromolds with a microhole array were precisely manufactured by a synchrotron LIGA process. Like in the traditional LIGA process, a deep X-ray lithography based on a synchrotron radiation was employed as the first manufacturing step. Due to the excellent optical performance of the synchrotron X-ray used, cylindrical micropillar arrays with high aspect ratio could be efficiently obtained. The fabricated microfeatures were then used as a master of the subsequent copper electroforming process, thereby resulting in copper micromolds with a microhole array. Thermoplastic hot embossing experiments with the copper micromolds were carried out for imprinting cylindrical microfeatures onto a polystyrene sheet. Through the hot embossing, the effect of embossing temperature and usefulness of the present manufacturing method could be verified.

Real Time Imaging of Solidification Behavior by Synchrotron X-ray Radiography (싱크로트론 X-선 투과영상법을 활용한 응고거동 실시간 관찰)

  • Lee, Sang-Mok;Yasuda, Hideyuki
    • Journal of Korea Foundry Society
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    • v.30 no.1
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    • pp.5-13
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    • 2010
  • This article aims to introduce the synchrotron radiation for its utilization in the casting and solidification fields as an unique tool for observation of real time phenomena of molten metal during solidification. General features of the synchrotron radiation were briefly introduced for readers in the casting and solidification fields, with no background regarding to synchrotron radiation. And basic principles of imaging technologies using synchrotron light for in-situ observation of molten metal were explained together with exemplary research works, which were reported on the casting and solidification fields in recent years. As a practical guide, real time observation of Al-Si casting alloy was introduced with experimental facilities, image acquisition, and processing together with representative results.