MAIRE: Solar Proton Ground Level Event

There is a lot of interest in the calculation of the radiation effects on microelectronics and to flight personnel caused by solar particle events in the atmosphere. The response matrix approach of MAIRE allows for rapid calculation of the secondary particle spectra in the atmosphere caused by solar energetic particles, if the solar proton spectrum at the top of the atmosphere can be determined, which is not an easy task. Ground level events (GLE) are the most intense class of event and their spectra can be estimated from the neutron monitor responses strategically located at various latitudes around the globe [1] [2].

MAIRE has built-in peak flux spectra for a number of the GLEs. The user can obtain the secondary radiation caused by any of these events at the specified location in the atmosphere. The most intense solar particle event measured to date is the ground level event of 23rd February 1956. Example-4 shows the secondary particle spectra at 17 km altitude and 1 GV rigidity cutoff, as calculated by MAIRE. At the peak of the event, the secondary neutron flux at 1 MeV is about three orders of magnitude higher than the normal cosmic ray induced radiation level.

[1] Dyer, C.S., et al., Calculations and Observations of Solar Particle Enhancements to the Radiation Environment at Aircraft Altitudes. Adv. Space Res. 32(1), 81-93,2003.
[2] Clucas. S. N., et al., The Radiation in the Upper Atmosphere During Major Solar Particle Events, COSPAR, 2004.