Near real-time determination of ionization and radiation dose rates induced by cosmic rays in the Earth ’ s atmosphere – a NMDB application

A real-time database for high resolution neutron monitor data is being developed within the Neutron Monitor Database (NMDB) project funded by the European Union’s 7th Framework Programme (www.nmdb.eu). In addition to the database, the NMDB project will provide different data products. One of the applications is the near real-time determination of ionization and radiation dose rates induced by cosmic rays in the Earth’s atmosphere. The procedure of this application has four steps. In the first step, the near-Earth cosmic ray flux outside the geomagnetosphere is computed based on the NMDB. This flux is the basis for the next step, which is computing the cosmic ray flux at the top of the Earth’s atmosphere for a 5x 5 grid in geographic coordinates. In the third step, at each grid point the secondary cosmic ray flux and the ionization of the atoms and molecules in the atmosphere at selected altitudes are processed with the Geant4 software package PLANETOCOSMICS developed at the University of Bern. Finally, the radiation dose rates at typical aircraft altitude are evaluated by using published flux to dose conversion factors. The paper presents the procedure and compares first computed radiation dose values with other theoretical results.