Author
X. J. Bi
Bio: X. J. Bi is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Air shower & Cosmic ray. The author has an hindex of 2, co-authored 2 publications receiving 260 citations.
Topics: Air shower, Cosmic ray, Galactic corona, Galactic plane, Milky Way
Papers
More filters
Hirosaki University1, Saitama University2, Chinese Academy of Sciences3, Yokohama National University4, Hebei Normal University5, Tibet University6, Shandong University7, Southwest Jiaotong University8, Yunnan University9, Kanagawa University10, Utsunomiya University11, University of Tokyo12, Konan University13, Shibaura Institute of Technology14, Shinshu University15, Tsinghua University16, Waseda University17, National Institute of Informatics18, College of Industrial Technology19, Shonan Institute of Technology20
TL;DR: Two-dimensional high-precision anisotropy measurement for energies from a few to several hundred teraelectronvolts (TeV) is presented, using the large data sample of the Tibet Air Shower Arrays, revealing finer details of the known anisotropies.
Abstract: The intensity of Galactic cosmic rays is nearly isotropic because of the influence of magnetic fields in the Milky Way. Here, we present two-dimensional high-precision anisotropy measurement for energies from a few to several hundred teraelectronvolts (TeV), using the large data sample of the Tibet Air Shower Arrays. Besides revealing finer details of the known anisotropies, a new component of Galactic cosmic ray anisotropy in sidereal time is uncovered around the Cygnus region direction. For cosmic-ray energies up to a few hundred TeV, all components of anisotropies fade away, showing a corotation of Galactic cosmic rays with the local Galactic magnetic environment. These results have broad implications for a comprehensive understanding of cosmic rays, supernovae, magnetic fields, and heliospheric and Galactic dynamic environments.
259 citations
Hirosaki University1, Saitama University2, Chinese Academy of Sciences3, Yokohama National University4, Hebei Normal University5, Tibet University6, Shandong University7, Yunnan University8, Kanagawa University9, Utsunomiya University10, University of Tokyo11, Konan University12, Shibaura Institute of Technology13, Shinshu University14, Waseda University15, National Institute of Informatics16, College of Industrial Technology17, Shonan Institute of Technology18
TL;DR: In this article, a water-Cherenkov-type muon-detector array (Tibet MD array) was built around the 37 000 m2 Tibet air shower array, which is already constructed at 4300 m above sea level in Tibet, China.
Abstract: We propose to build a large water-Cherenkov-type muon-detector array (Tibet MD array) around the 37 000 m2 Tibet air shower array (Tibet AS array) already constructed at 4300 m above sea level in Tibet, China. Each muon detector is a waterproof concrete pool, 6 m wide × 6 m long × 1.5 m deep in size, equipped with a 20 inch-in-diameter PMT. The Tibet MD array consists of 240 muon detectors set up 2.5 m underground. Its total effective area will be 8640 m2 for muon detection. The Tibet MD array will significantly improve gamma-ray sensitivity of the Tibet AS array in the 100 TeV region (10–1000 TeV) by means of gamma/hadron separation based on counting the number of muons accompanying an air shower. The Tibet AS+MD array will have the sensitivity to gamma rays in the 100 TeV region by an order of magnitude better than any other previous existing detectors in the world.
11 citations
Cited by
More filters
TL;DR: PAMELA data challenge the current paradigm of cosmic-ray acceleration in supernova remnants followed by diffusive propagation in the Galaxy and find that the spectral shapes of these two species are different and cannot be described well by a single power law.
Abstract: Protons and helium nuclei are the most abundant components of the cosmic radiation Precise measurements of their fluxes are needed to understand the acceleration and subsequent propagation of cosmic rays in our Galaxy We report precision measurements of the proton and helium spectra in the rigidity range 1 gigavolt to 12 teravolts performed by the satellite-borne experiment PAMELA (payload for antimatter matter exploration and light-nuclei astrophysics) We find that the spectral shapes of these two species are different and cannot be described well by a single power law These data challenge the current paradigm of cosmic-ray acceleration in supernova remnants followed by diffusive propagation in the Galaxy More complex processes of acceleration and propagation of cosmic rays are required to explain the spectral structures observed in our data
900 citations
TL;DR: In this paper, a review summarizes recent developments in the understanding of high-energy cosmic rays focusing on galactic and presumably extragalactic particles in the energy range from the knee (1015 eV ) up to the highest energies observed ( > 10 20 eV).
300 citations
National Research Council1, United States Naval Research Laboratory2, University of California, Irvine3, University of California, Santa Cruz4, University of Maryland, College Park5, Los Alamos National Laboratory6, George Mason University7, New York University8, National Autonomous University of Mexico9, Michigan State University10, Goddard Space Flight Center11, University of New Hampshire12, Ohio State University13
TL;DR: In this article, a harmonic analysis of the large-scale cosmic-ray (CR) anisotropy as observed by the Milagro observatory is presented, which is a water Cherenkov detector located in the Jemez mountains near Los Alamos, New Mexico.
Abstract: Results are presented of a harmonic analysis of the large-scale cosmic-ray (CR) anisotropy as observed by the Milagro observatory. We show a two-dimensional display of the sidereal anisotropy projections in right ascension (R.A.) generated by the fitting of three harmonics to 18 separate declination bands. The Milagro observatory is a water Cherenkov detector located in the Jemez mountains near Los Alamos, New Mexico. With a high duty cycle and large field of view, Milagro is an excellent instrument for measuring this anisotropy with high sensitivity at TeV energies. The analysis is conducted using a seven-year data sample consisting of more than 95 billion events, the largest such data set in existence. We observe an anisotropy with a magnitude around 0.1% for CRs with a median energy of 6 TeV. The dominant feature is a deficit region of depth (2.49 ± 0.02 stat. ± 0.09 sys.) ×10–3 in the direction of the Galactic north pole centered at 189 deg R.A. We observe a steady increase in the magnitude of the signal over seven years.
200 citations
University of Florence1, University of Naples Federico II2, Lebedev Physical Institute3, University of Bari4, Stockholm University5, Royal Institute of Technology6, International Federation of Accountants7, University of Rome Tor Vergata8, University of Trieste9, National Research Nuclear University MEPhI10, Folkwang University of the Arts11, Agenzia Spaziale Italiana12, China University of Geosciences (Wuhan)13
TL;DR: The PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) satellite-borne experiment was launched onboard the Russian Resurs-DK1 satellite by a...
188 citations
Michigan State University1, University of California, Irvine2, University of Maryland, College Park3, Los Alamos National Laboratory4, University of California, Santa Cruz5, George Mason University6, New York University7, Karlsruhe Institute of Technology8, National Autonomous University of Mexico9, Goddard Space Flight Center10, Stanford University11, University of New Hampshire12, Ohio State University13, Max Planck Society14
TL;DR: In this article, the Milagro gamma-ray observatory was used to study the Cygnus region of the galactic plane, showing that it contains at least one new source, MGRO J2019+37 which is 10.9 σ above the isotropic background.
Abstract: The diffuse gamma radiation arising from the interaction of cosmic-ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of the cosmic rays. Data from the Milagro gamma-ray observatory—a water Cerenkov detector that continuously views ~2 sr of the overhead sky—shows that the brightest extended region in the entire northern sky is the Cygnus region of the Galactic plane. The TeV image of the Cygnus region contains at least one new source, MGRO J2019+37, which is 10.9 σ above the isotropic background, as well as correlations with the matter density in the region. However, the gamma-ray flux from the Cygnus region (after excluding MGRO J2019+37) as measured at ~12 TeV exceeds that predicted from a model of cosmic-ray production and propagation. This observation indicates the existence of either hard-spectrum cosmic-ray sources and/or unresolved sources of TeV gamma rays in the region.
181 citations