COMPARISON OF CODES ASSESSING GALACTIC COSMIC RADIATION EXPOSURE OF AIRCRAFT CREW J. F. Bottollier-Depois 1, *, P. Beck 2 , B. Bennett 3 , L. Bennett 3 , R. Bu ¨tikofer 4 , I. Clairand 1 , L. Desorgher 5 , C. Dyer 6 , E. Felsberger 7 , E. Flu ¨ ckiger 4 , A. Hands 6 , P. Kindl 8 , M. Latocha 2 , B. Lewis 3 , G. Leuthold 9 , T. Maczka 9 , V. Mares 9 , M. J. McCall 10 , K. O’Brien 11 , S. Rollet 2 ,W. Ru ¨hm 9 and F. Wissmann 12 1 Institute for Radiological Protection and Nuclear Safety, F-92262 Fontenay-aux-Roses, France 2 Department Health and Environment, ARC, Austrian Research Centers, A-2444 Seibersdorf, Austria 3 Royal Military College, Kingston, ON, Canada, K7K 7B4 4 University of Bern, Bern, Switzerland 5 SpaceIT GmbH, Bern, Switzerland 6 Aerospace Division, QinetiQ, Farnborough, UK 7 IASON GmbH, Feldkirchner Straße 4, A-8054 Graz-Seiersberg, Austria 8 Institute for Material Physics, Graz University of Technology, A-8010 Graz, Austria 9 Helmholz Zentrum Mu ¨nchen, Institute of Radiation Protection, 85758 Neuherberg, Germany 10 PCaire Inc., 38 Colonnade Rd, Ottawa, Canada 11 Department of Physics and Astronomy, Northern Arizona University, Flagstaff, AZ 86011-6010, USA 12 Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany The assessment of the exposure to cosmic radiation onboard aircraft is one of the preoccupations of bodies responsible for radiation protection. Cosmic particle flux is significantly higher onboard aircraft than at ground level and its intensity depends on the solar activity. The dose is usually estimated using codes validated by the experimental data. In this paper, a comparison of various codes is presented, some of them are used routinely, to assess the dose received by the aircraft crew caused by the galactic cosmic radiation. Results are provided for periods close to solar maximum and minimum and for selected flights covering major commercial routes in the world. The overall agreement between the codes, particularly for those routinely used foraircraft crew dosimetry, was better than +20 % from the median in all but two cases. The agreement within the codes is considered to be fully satisfactory for radiation protection purposes. INTRODUCTION Since 1996, aircraft crews in the European Union (EU) have been recognised as occupationally exposed workers owing to their exposure to cosmic radiation in the atmosphere. By 2006, the directive EURATOM/96/29 was implemented in all EU member states and proper measures must have been undertaken to assess the dose. Since the radiation field is very complex in terms of particle compo- sition and particle energies, the dose assessment is a very difficult task. During the last decade, many research projects were focused on this problem. One of the main outcomes was that dose assessment can be done by using program codes that were developed during the last few years. The use of a predictive code is possible when the radiation field is rather constant and sudden changes in the local dose rates are not expected, except for the case of rarely occur- ring ground-level enhancements associated with solar-particle events having a high fluence rate of particles with high energy. Therefore, the time, geo- graphical information on latitude, longitude and barometric altitude of the flown routes are the basic input parameters for any calculation. The aim of this study is to compare the calculated dose and dose rates of those codes (see Table 1) that are mainly used in Europe and for which the provi- ders agreed to perform the calculations. Some of the codes are routinely used for radiation protection pur- poses, whereas others are purely for scientific use. For routine radiation protection purposes, i.e. dose assessment of aircraft crew, acode must be able to calculate the effective dose E as the radiation pro- tection quantity. However, the validation of codes can only be done by comparing the measured ambient dose equivalent H*(10) (or its rate) to the calculated value. Therefore, the ability to calculate H*(10) is mandatory for all codes. The different codes used are summarised in Table 1. Some of them are based on Monte Carlo simulations of the radiation field (AVIDOS, EPCARD, QARM); one code (FREE) uses the analytical calculation of the particle transport through the atmosphere based on PLOTINUS calcu- lations. These solutions use the evaluated particle fluxes to calculate the ambient dose equivalent and effective dose by using appropriate conversion *Corresponding author: jeanfrancois.bottollier@irsn.fr # The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org Radiation Protection Dosimetry (2009), Vol. 136, No.4, pp. 317–323 doi:10.1093/rpd/ncp159 Advance Access publication 23 August 2009