Sensitivity of a neutron monitor to galactic cosmic rays Original Research Article

We studied the sensitivity of a neutron monitor to Galactic cosmic rays depending on energy of cosmic ray particles in the interstellar medium. This is important for studying of the interstellar spectrum of cosmic rays and details of solar modulation by means of the world neutron monitor network. We calculated the expected response of a standard sea-level neutron monitor vs. energy of cosmic ray particles. First, we studied modulation of a monoenergetic flux of cosmic rays. Then the specific atmospheric yield function of a neutron monitor was applied to the calculated flux of cosmic rays at the Earthʹs orbit. The obtained response function, being convoluted with the model interstellar spectrum of cosmic rays, gives a maximum of neutron monitor sensitivity at around several GV of rigidity of cosmic ray particles. We performed calculations for weak (φ = 350 MV) and medium (φ = 750 MV) modulation strength. A normalisation of neutron monitor count rate is suggested which can give an experimental measure of the overall solar modulation of cosmic rays.