Differences between cosmic-ray intensities observed in polar and nonpolar regions

Abstract

The directions of maximum sensitivity in space for the neutron monitors in polar regions (Resolute, Mawson, etc.) make large angles with the ecliptic plane in contrast with the neutron monitors at lower latitudes (Ottawa, Deep River, etc.). Hence a comparison of the intensities recorded in the two regions would reveal differential changes, if any, between the cosmic-ray intensity level inside and outside the ecliptic plane. Such an analysis was carried out and revealed differences as large as±2% in the daily means which were far outside the Poisson statistical erros. However, it was found that whereas the genuineness of some of these is not ruled out, a major part had to be attributed to unsatisfactory operation of instruments. This was so not only in the early part of I.G.Y. (1957) but even in 1963 and also for some super neutron monitors operating in 1964, thus nullifying to a great extent the advantages these would have had because of their high statistical accuracy. The need for operating at least three independent sections of a neutron pile and ensuring the parallel running of at least two of these all the time, is emphasized.