Neutron monitor yield function at several altitudes above sea level: new improved computation

For an analysis of solar particle events using neutron monitor data it is necessary to model the global neutron monitor network response. This is possible using the corresponding yield function(s). We present new improved computations of standard 6NM64 yield functions for primary protons and alpha particles. The yield functions were computed at several depths, encompassing all the historical and existing neutron monitors. The computations were carried out with the Planetocosmics Monte-Carlo tool for extensive air shower simulations. All the secondary particles, which contribute to the count rate of a NM were considered. An effect of the geometrical correction of the NM effective area was also considered above 5-10 GeV/nucleon. The new NM yield function is compared with previous estimates and with experimental altitude and latitude surveys. The new NM yield function was applied to an analysis of ground level enhancement on the basis of global NM network data. The application of previously used double attenuation length method and the new yield function for ground level enhancement analysis are compared.