@article{3068420, title = "Improved Approach in the Coupling Function Between Primary and Ground Level Cosmic Ray Particles Based on Neutron Monitor Data", author = "Xaplanteris, L. and Livada, M. and Mavromichalaki, H. and Dorman, L. and Georgoulis, M.K. and Sarris, T.E.", journal = "SOLAR PHYSICS", year = "2021", volume = "296", number = "6", publisher = "Springer Science and Business Media B.V.", issn = "0038-0938", doi = "10.1007/s11207-021-01836-y", abstract = "In this work an improved approach of existing approximations on the coupling function between primary and ground-level cosmic-ray particles is presented. The proposed coupling function is analytically derived based on a formalism used in Quantum Field Theory calculations. It is upgraded compared to previous versions with the inclusion of a wider energy spectrum that is extended to lower energies, as well as an altitude correction factor, also derived analytically. The improved approximations are applied to two cases of Forbush decreases detected in March 2012 and September 2017. In the analytical procedure for the derivation of the primary cosmic-ray spectrum during these events, we also consider the energy spectrum exponent γ to be varied with time. For the validation of the findings, we present a direct comparison between the primary spectrum and the amplitude values derived by the proposed method and the obtained time series of the cosmic-ray intensity at the rigidity of 10 GV obtained from the Global Survey Method. The two sets of results are found to be in very good agreement for both events as denoted by the Pearson correlation factors and slope values of their scatter plots. In such way we determine the validity and applicability of our method to Forbush decreases as well as to other cosmic-ray phenomena, thus introducing a new, alternative way of inferring the primary cosmic-ray intensity. © 2021, The Author(s), under exclusive licence to Springer Nature B.V." }