The muon spectra near the geomagnetic equator

Abstract

The vertical momentum spectrum and the charge ratio of cosmic-ray muons have been investigated in the range 0.3–25 GeV/c at a geomagnetic latitude of λ = 9 °N at sea level. The investigations have been performed by means of a magnetic spectrograph using the spark chamber technique for track location. The measured spectrum in the low-energy region is about 20% smaller than the spectra at high geomagnetic latitudes. The integral intensity for particles which penetrate more than 15 cm of lead is 7.25 × 10−3 cm−2 s−1 sr−1. The theoretical spectrum after Olbert is in agreement with our results.