Mini Neutron Monitors at Concordia Research Station, Central Antarctica

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  • ABSTRACT

    Two mini neutron monitors are installed at Concordia research station (Dome C, Central Antarctica, 75°06'S, 123°23'E, 3,233 m.a.s.l.). The site has unique properties ideal for cosmic ray measurements, especially for the detection of solar energetic particles: very low cutoff rigidity < 0.01 GV, high elevation and poleward asymptotic acceptance cones pointing to geographical latitudes > 75°S. The instruments consist of a standard neutron monitor and a "bare" (lead-free) neutron monitor. The instrument operation started in mid-January 2015. The barometric correction coefficients were computed for the period from 1 February to 31 July 2015. Several interesting events, including two notable Forbush decreases on 17 March 2015 and 22 June 2015, and a solar particle event of 29 October 2015 were registered. The data sets are available at cosmicrays.oulu.fi and nmdb.eu.


  • KEYWORD

    neutron monitor , solar energetic particle , Antarctica

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  • [Fig. 1.] Cosmic ray stations in Antarctica. A modified image of ⓒHeraldry/Wikimedia Commons/GFDL.
    Cosmic ray stations in Antarctica. A modified image of ⓒHeraldry/Wikimedia Commons/GFDL.
  • [Fig. 2.] Asymptotic acceptance cones for several selected cosmic ray stations at high geomagnetic latitudes . The digits indicate particle rigidities for the cones in GV. Modified images of ⓒGringer/Wikimedia Commons/GFDL.
    Asymptotic acceptance cones for several selected cosmic ray stations at high geomagnetic latitudes . The digits indicate particle rigidities for the cones in GV. Modified images of ⓒGringer/Wikimedia Commons/GFDL.
  • [Fig. 3.] Schematic of the design of a standard neutron monitor.
    Schematic of the design of a standard neutron monitor.
  • [Fig. 4.] Standard (RHS, white front panel) and "bare" (LHS, black front panel) mini neutron monitors installed in the physics shelter at Concordia research station.
    Standard (RHS, white front panel) and "bare" (LHS, black front panel) mini neutron monitors installed in the physics shelter at Concordia research station.
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  • [Fig. 5.] Count rates of the standard-design neutron monitor at Dome C (DOMC, top panel), "bare" neutron monitor (DOMB, middle panel) and the Oulu neutron monitor (bottom panel). The values are corrected for atmospheric pressure and filtered with a rectangular 24 hour window. The 100% level corresponds to the maximum count rate for the time interval.
    Count rates of the standard-design neutron monitor at Dome C (DOMC, top panel), "bare" neutron monitor (DOMB, middle panel) and the Oulu neutron monitor (bottom panel). The values are corrected for atmospheric pressure and filtered with a rectangular 24 hour window. The 100% level corresponds to the maximum count rate for the time interval.
  • [Fig. 6.] Forbush decrease at 17 March 2015 registered by the standard-design neutron monitor at Dome C (DOMC, top panel), the "bare" neutron monitor (DOMB, middle panel), and the Oulu neutron monitor (bottom panel). The count rates are corrected for atmospheric pressure. The level before the Forbush decrease is set as 100%.
    Forbush decrease at 17 March 2015 registered by the standard-design neutron monitor at Dome C (DOMC, top panel), the "bare" neutron monitor (DOMB, middle panel), and the Oulu neutron monitor (bottom panel). The count rates are corrected for atmospheric pressure. The level before the Forbush decrease is set as 100%.
  • [Fig. 7.] Forbush decrease at 22 June 2015 registered by the standard-design neutron monitor at Dome C (DOMC, top panel), the "bare" neutron monitor (DOMB, middle panel), and the Oulu neutron monitor (bottom panel). The count rates are corrected for atmospheric pressure. The level before the Forbush decrease is set as 100%.
    Forbush decrease at 22 June 2015 registered by the standard-design neutron monitor at Dome C (DOMC, top panel), the "bare" neutron monitor (DOMB, middle panel), and the Oulu neutron monitor (bottom panel). The count rates are corrected for atmospheric pressure. The level before the Forbush decrease is set as 100%.
  • [Fig. 8.] The enhancement of the neutron monitor count rates on 7 June 2015. The standard-design neutron monitor at Dome C (DOMC, top panel), the "bare" neutron monitor (DOMB, middle panel), and the Oulu neutron monitor (OULU, bottom panel). The count rates are corrected for atmospheric pressure. The level before the event is set as 100%. The event is highlighted in grey.
    The enhancement of the neutron monitor count rates on 7 June 2015. The standard-design neutron monitor at Dome C (DOMC, top panel), the "bare" neutron monitor (DOMB, middle panel), and the Oulu neutron monitor (OULU, bottom panel). The count rates are corrected for atmospheric pressure. The level before the event is set as 100%. The event is highlighted in grey.