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Measurements during solar particle events with dosemeters flying permanently on-board Concorde are used to develop a semi-empirical model, called SiGLE. The model is intended to calculate, for a given flight plan, the dose equivalent received during a solar particle event observed with ground-based neutron monitors. It is successfully in operation in the SIEVERT computerised system intended to improve monitoring of radiation dose received by aircrews, in application to a European Directive. The semi-empirical model is applied to evaluate, for most exposed routes, the radiation doses corresponding to the GLEs observed since 1942 with ion chambers or neutron monitors. The results for the largest GLEs observed in the past are discussed in terms of radiation risk, and guidelines are suggested concerning possible alerts to the aeroplanes in case of events of exceptional magnitude.

Calculations of fluence-to-effective dose conversion coefficients have typically been limited to the standard irradiation geometries of the human body: anterior-to-posterior (AP), posterior-to-anterior (PA), lateral from the right side to the left side (RLAT), lateral from the left side to the right side (LLAT), rotational around the vertical axis (ROT), and isotropic incidence from all directions (ISO). In order to estimate the doses to air crew members exposed to cosmic radiation, the geometrical conditions of irradiation are usually assumed to be isotropic. However, the assumption of isotropic irradiation is in many cases invalid for the high energy component of the radiation field, which is often peaked in the forward direction. Therefore, it was considered useful to extend the calculations of conversion coefficients to other geometries. New sets of conversion coefficients fluence-to-effective dose are presented for the semi-isotropic irradiation of the human body and for the irradiation from the top. Their application to cosmic ray dosimetry is discussed.

Evaluation of LiF:Mg,Ti thermoluminescence dosemeters (TLDs) according to the high-temperature ratio (HTR) method enables the determination of the dose-average linear energy transfer (LET), the mean quality factor and the dose equivalent in mixed radiation fields of unknown composition. The neutron contribution is assessed by the Extended Pair method calibrated in the CERN-EU High-Energy Reference Field (CERF). The advantages of the small passive detectors as an easy-to-handle monitoring system for in-flight surveillance are demonstrated by measurements on-board north-bound and trans-equatorial flights. The experimental results are compared with calculations by the well-established CARI code.

The spectral distribution of the neutron fluence rate was determined on-board a series of eight trans-atlantic flights between Cologne (Germany) and Washington, DC (USA), using a passive Bonner Sphere spectrometer based on thermoluminescence detectors. Contrary to the commonly applied active systems, the passive instrument facilitates a complete discrimination of gamma ray and charged particle-induced events in the detector count rate. The system was calibrated in the CERN-EU High-Energy Reference Field (CERF). The measured spectra are compared with FLUKA Monte Carlo simulations and show excellent agreement.

Aircrew exposure represents one of the recent subjects of occupational individual dosimetry. Since 1991 many new results have been found; there is however a need to gather further data on this exposure and its variation with geomagnetic position, solar activity and flight route parameters. Since 2001, many individual and six long-term monitoring programmes have been conducted onboard aircraft of Czech Airlines (CSA). In these programmes, a Si-diode spectrometer was fixed in an aircraft. Together with it, passive dosemeters thermoluminescent detector, track-etch based neutron dosemeter linear energy transfer and spectrometer) were exposed. More than 700 regular commercial flights were monitored in this manner. CSA supplied us also with full navigation data, which allowed us to calculate the exposure levels using EPCARD 3.2 and CARI6 codes. Direct experimental readings obtained with the detectors mentioned above were interpreted on the basis of calibrations in on-Earth reference fields and compared with calculated data. A satisfactory correlation between all sets of data was observed.

Owing to their professional activity, flight crews may receive a dose of some millisieverts within a year; airline passengers may also be concerned. The effective dose is to be estimated using various experimental and calculation tools. The European project DOSMAX (Dosimetry of Aircrew Exposure during Solar Maximum) was initiated in 2000 extending to 2004 to complete studies over the current solar cycle during the solar maximum phase. To compare various dosemeters in real conditions simultaneously in the same radiation field, an intercomparison was organised aboard a Paris-Tokyo round-trip flight. Both passive and active detectors were used. Good agreement was observed for instruments determining the different components of the radiation field; the mean ambient dose equivalent for the round trip was 129 +/- 10 microSv. The agreement of values obtained for the total dose obtained by measurements and by calculations is very satisfying.