Solar Diurnal Variations of Cosmic Ray Mesons as Seen by a Vertical Narrow-Angle Telescope

Abstract

The solar daily variations of the vertical intensity of cosmic radiation have been investigated in Wellington between May and November 1957 with the aid of a telescope with very small aperture; precautions were taken against lateral showers. The station was situated at an altitude of 130 metres above sea-level, geomagnetic latitude 45°S. After application of a correction for barometric pressure a significant diurnal variation was found with amplitude (3.16 ± 0.53)% of the mean counting rate and a maximum between 1500 and 1600 hours solar time. No significant semi-diurnal variation was found after allowance had been made for barometric changes although a dominant 12-hour wave was present in the raw data. The significance of the results obtained has been considered in the light of proposed explanations.