GeV Solar Energetic Particle Observation and Search by IceTop from 2011 to 2016
P. Evenson, IceCube Collaboration, P.S. Mangeard, P. Muangha, R. Pyle, D. Ruffolo, A. Sáiz
Only three Ground Level Enhancements (GLEs) produced by GeV-range solar energetic particles have been confirmed in the present solar cycle, and those have been quite small by historical standards. At the same time direct observations of high energy solar particles from spacecraft have become available. The combination of instruments at the Amundsen - Scott Station at the geographic South Pole offers an opportunity to span the two disparate sets of measurements. Operating at high altitude and low geomagnetic cutoff the neutron monitor at Pole has nevertheless traditionally been accepted as making a "ground level" observation. An enhanced array of bare neutron detectors and IceTop (surface ice Cherenkov detectors in the IceCube Neutrino Observatory) in principle allow spectral information to be extracted from events that previously were too small to use geomagnetic techniques to obtain spectra. We report our spectral measurements for the three confirmed GLE and compare them to other available data on these events. We also present preliminary results of an ongoing study of 34 particle events selected to have significant enhancements in the > 100 MeV channel in GOES data in terms of possible detections and sensitivity limits.