Measurement of Neutron Radiation Exposure of Commercial Airline Pilots Using Bubble Detectors

Neutron bubble detectors have been used over a 1-yr period by commercial airline pilots from Air Canada and Air France to measure the high-altitude neutron radiation exposure produced by galactic cosmic rays. The present work yielded measurements of the neutron flux of 1.0 to 4.6 n/cm^2.s, and the neutron dose equivalent rates of 1.7 to 7.7/µSv/h. These measurements are in agreement with previous studies using high-altitude aircraft and conventional neutron instrumentation. The total dose equivalents for the Air Canada flights are also consistent with predictions of the CARI code. Considering that the neutron component contributes ∼50% of the total dose equivalent, this study indicates that the annual dose for the air crew member would exceed the new recommendations of the International Commission on Radiological Protection (ICRP-60) for the general public.