• Title/Summary/Keyword: generate and relativistic electrons

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A correlation study of substorm injections and ULF power with relativistic electron events

  • Jeong-A Hwang;Gyeong-Uk Min;Ji-Na Lee;Dae-Yeong Lee
    • Bulletin of the Korean Space Science Society
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    • 2004.04a
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    • pp.88-88
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    • 2004
  • We demonstrate that the flux levels of post-storm relativistic electrons are well correlated with the amount of electrons of the energy about 100 keV injected during substorms, while the power of ULF is more or less related to the spectral hardening of these seed electrons. Hence, the existence of ULF alone during the storm time does not necessarily cause flux increase of relativistic electrons as storms do not always generate sufficient amount of seed electrons of this energy range. (omitted)

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THE ELECTRON FRACTION AND THE FERMI ENERGY OF RELATIVISTIC ELECTRONS IN A NEUTRON STAR

  • GAO, ZHI FU;LI, X.D.;WANG, N.;PENG, Q.H.
    • Publications of The Korean Astronomical Society
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    • v.30 no.2
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    • pp.569-572
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    • 2015
  • We first deduce a uniform formula forthe Fermi energy of degenerate and relativistic electrons in the weak-magnetic field approximation. Then we obtain an expression of the special solution for the electron Fermi energy through this formula, and express the electron Fermi energy as a function of electron fraction and matter density. Our method is universally suitable for relativistic electron- matter regions in neutron stars in the weak-magnetic field approximation.

Electron Pre-acceleration in Weak Quasi-perpendicular Shocks in Clusters of Galaxies

  • Ha, Ji-Hoon;Kang, Hyesung;Ryu, Dongsu
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.49.1-49.1
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    • 2019
  • Giant radio relics in the outskirts of galaxy clusters have been observed and they are interpreted as synchrotron emission from relativistic electrons accelerated via diffusive shock acceleration (DSA) in weak shocks of Ms < 3.0. In the DSA theory, the particle momentum should be greater than a few times the momentum of thermal protons to cross the shock transition and participate in the Fermi acceleration process. In the equilibrium, the momentum of thermal electrons is much smaller than the momentum of thermal protons, so electrons need to be pre-accelerated before they can go through DSA. To investigate such electron injection process, we study the electron pre-acceleration in weak quasi-perpendicular shocks (Ms = 2.0 - 3.0) in an ICM plasma (kT = 8.6 keV, beta = 100) through 2D particle-in-cell simulations. It is known that in quasi-perpendicular shocks, a substantial fraction of electrons could be reflected upstream, gain energy via shock drift acceleration (SDA), and generate oblique waves via the electron firehose instability (EFI), leading the energization of electrons through wave-particle interactions. We find that such kinetic processes are effective only in supercritical shocks above a critical Mach number, $Ms{\ast}{\sim}2.3$. In addition, even in shocks with Ms > 2.3, energized electrons may not reach high energies to be injected to DSA, because the oblique EFI alone fails to generate long-wavelength waves. Our results should have implications for the origin and nature of radio relics.

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Study on terahertz (THz) photoconversion technology based on hyperfine energy-level splitting of Positronium (Ps) generated from relativistic electron beams

  • Sun-Hong Min;Chawon Park;Ilsung Cho;Minho Kim;Sukhwal Ma;Won Taek Hwang;Kyeong Min Kim;Seungwoo Park;Min Young Lee;Eun Ju Kim;Kyo Chul Lee;Yong Jin Lee;Bong Hwan Hong
    • Journal of Radiopharmaceuticals and Molecular Probes
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    • v.6 no.2
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    • pp.102-115
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    • 2020
  • In the state of Positronium (Ps), which is an unstable material created by the temporary combination of electrons and positrons, the imaging technology through photo-conversion methodology is emerging as a new research theme under resonance conditions through terahertz electromagnetic waves. Normally, Positronium can be observed in the positron emission computed tomography (PET) process when an unstable, separate state that remains after the pair annihilation of an electron and a positron remains. In this study, terahertz (THz) waves and Cherenkov radiation (CR) are generated using the principle of ponderomotive force in the plasma wake-field acceleration, and electrons and positrons are simultaneously generated by using a relativistic electron beam without using a PET device. We confirm the possibility of Positronium photoconversion technology in terahertz electromagnetic resonance conditions through experimental studies that generate an unstable state. Here, a relativistic electron beam (REB) energy of 0.5 MeV (γ=2) was used, and the terahertz wave frequencies is G-band. Meanwhile, a THz wave mode converting three-stepped axicon lens was used to apply the photoconversion technology. Through this, light emission in the form of a luminescence-converted Bessel beam can be verified. In the future, it can be used complementarily with PET in nuclear medicine in the field of medical imaging.