Ground Level Enhancement of May 17, 2012 Observed at South Pole
Abstract
With both high altitude and low geomagnetic cutoff, the Amundsen Scott station located at the south geographic pole is arguably the most sensitive surface location on Earth for the detection of solar energetic particles. Three complementary detectors are now in operation there. IceTop is an array of 162 ice Cherenkov detectors each comprising approximately 2000 kg of clear ice. Each detector is viewed by photomultipliers feeding rate scalers set to different threshold levels, typically counting 1 kilohertz and above. The array of thresholds allows IceTop to determine the energy spectrum of the solar energetic particles. The South Pole neutron monitor, with a long operating history at this location, is a standard 3NM64. Additionally there is an array of bare neutron detectors (without lead shielding) referred to as the Polar Bares. Monitors and Bares respond to successively lower energy particles than the Cherenkov detectors thereby extending the spectral response. In this work we examine the Ground Level Enhancement (GLE) of May 17, 2012, related to an M5.1 solar flare, which was the first GLE in this solar cycle and the first one since December 2006. We derive the energy spectrum of the solar particles and interpret the result in the context of observations from the global neutron monitor network.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2013
- Bibcode:
- 2013AGUSMSH33B..07E
- Keywords:
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- 7514 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY / Energetic particles;
- 7519 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY / Flares;
- 7594 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY / Instruments and techniques