Determination of the solar-flare cosmic-ray rigidity spectrum using the worldwide neutron monitor network

Abstract

The determination of the rigidity spectrum of solar-flare-produced cosmic rays is examined. A method based on the ratio of relative enhancements observed at two stations sufficiently separated in latitude is discussed, and graphs are presented showing the expected ratio of enhancements as a function of the spectral exponent of the flare-produced cosmic rays for 6 pairs of stations. This method, which assumes that the cosmic-ray particles arrive at the earth isotropically, is then applied to the 28 January 1967 event during which this condition of isotropy is shown to exist. An extension of this method to the case of anisotropic arrival of solar cosmic-ray particles using the concept of variational coefficient is outlined.