THE EFFECTIVE DIRECTIONAL SENSITIVITY OF COSMIC-RAY NEUTRON MONITORS

Abstract

The direction of maximum sensitivity of a neutron monitor is calculated numerically for a set of points on the same geomagnetic meridian but extending in latitude from the equator to the pole. This leads to two master curves, one for the longitude, the other for the latitude of this direction. From these curves this direction is obtained in geographic co-ordinates for some 20 cosmic-ray stations. The method of calculation is described taking into account atmospheric absorption and the energy spectrum of the incident particles. The aperture of the sensitive cone, or source width, is also calculated. Finally the accuracy of the results is discussed and the application of the concept of effective direction is described.