ATMOSPHERIC COSMIC-RAYS AND SOLAR ENERGETIC PARTICLES AT AIRCRAFT ALTITUDES

Galactic cosmic rays, which are thought to be produced and accelerated by a variety of mechanisms in the Milky Way galaxy, interact with the solar wind, the earth's magnetic field, and its atmosphere to produce hadron, lepton, and photon fields at aircraft altitudes that are quit e unlike anything produced in the laboratory. The energy spectra of th ese secondary particles extend from the lowest possible energy to ener gies over an EeV. In addition to cosmic rays, energetic particles, gen erated on the sun by solar flares or coronal mass ejections, bombard t he earth from time to time. These particles, while less energetic than cosmic rays, also produce radiation fields at aircraft altitudes whic h have qualitatively the same properties as cosmic rays. The authors h ave calculated atmospheric cosmic-ray angular fluxes, spectra, scalar fluxes, and ionization, and compared them with experimental data. Agre ement with these data is seen to be good. These data have been used to calculate equivalent doses in a simplified human phantom at aircraft altitudes and the estimated health risks to aircraft crews. The author s have also calculated the radiation doses from several large solar en ergetic particle events (known as GLEs, or Ground Level Events), which took place in 1989, including the very large event known as GLE 42, w hich took place on September 29th and 30th of that year. The spectra i ncident on the atmosphere were determined assuming diffusive shock the ory. Unfortunately, there are essentially no experimental data with wh ich to compare these calculations. Copyright (C) 1996 Elsevier Science .