Latitude effect of the low momentum muon spectrum at sea level

TLDR: The sea level absolute vertical cosmic ray muon spectra at 12 degrees N (Calcutta) have been measured in the range 0.35-2.2 GeV/c with a range spectrometer as mentioned in this paper.

Abstract: The sea level absolute vertical cosmic ray muon spectra at 12 degrees N (Calcutta) have been measured in the range 0.35-2.2 GeV/c with a range spectrometer. These spectra are, on the average, 12% higher than those of Bhattacharyya at the same place of observation. The lower value of intensities of Bhattacharyya might be due to underestimation of scattering corrections and rejections of a few per cent of 'single muons'. The measured differential spectrum may well be represented by a form-fit spectrum. The Durgapur spectrum of Nandi and Sinha at 12 degrees N at sea level is in agreement with the form fit spectrum up to 20 GeV/c. A comparison of this spectrum with the high latitude form-fit spectrum of De et al. gives 1.23, 1.25, 1.21 and 1.07 latitude effect at the momentum ranges 0.3-0.5, 0.5-1.0, 1.0-2.0 and 2.0 5.0 GeV/c respectively. These values are more or less in agreement with those predicted from Olbert. Above 5 GeV/c the latitude effect is observed to vanish.