The momentum spectrum of cosmic ray muons above 300 GeV/c in the vertical direction

Abstract

The sea-level vertical rauon momentum spectrum Has been measured in the momentum range 100 GeV/c to 3000 GeV/c, using the MARS spectrograph in Durham, The various instrumental effects which affect either the shape or the absolute intensity of the measured spectrum have been studied in detail. The analysis procedure has been discussed in detail including the accuracy of the analysis technique and the criteria for rejection of certain events. A simple muon production and propagation model has been used to predict the plon and kaon production spectra using the rauon spectrum derived from the results of this experiment. It has not been found possible to predict the ratio of the number of kaons to the number of pions produced at production and an estimate of this ratio (0.106) has been used to fit a constant exponent power law spectrum. The present results have been compared with those of other workers and are found to yield a smaller value of the exponent for the fitted power law production spectra. This result suggests that the pion and kaon production spectra are somewhat flatter than previously measured for momenta above 100 GeV/c by previous HAliS experiments(Ayre et al., 1975). The present results on the muon spectrum, however, ogree, within the limits of the statistical accuracy, with other spectrograph data. Comparison with surveys of indirect measurements of the aiuon momentum spectrum suggest that the present results give a higher absolute intensity for the muon momentum spectrum above 1000 3aV/c.