Investigation of cosmic rays and their secondaries at aircraft altitudes

A very extensive study of the radiation field at aircraft altitudes has been carried out over the last few years. These investigations formed part of a European wide collaboration involving several laboratories with extensive experience in cosmic ray research and/or dosimetry. Among the main topics investigated were the charge spectra, LET spectra, anisotropy and dose values. The measurements were performed on subsonic and supersonic flights covering a wide range of altitudes and latitudes. Several active and passive instruments were employed in these studies and some results obtained with nuclear track detectors are described here. Comparisons are made with the results of other experiments and theoretical estimates using computer codes.