High energy cosmic ray physics with underground muons in MACRO. II. Primary spectra and composition Academic Article uri icon


  • Multimuon data from the MACRO experiment at Gran Sasso have been analyzed using a new method, which allows one to estimate the primary cosmic ray fluxes. The estimated all-particle spectrum is higher and flatter than the one obtained from direct measurements but is consistent with EAS array measurements. The spectral indexes of the fitted energy spectrum are 2.56[Formula presented]0.05 for [Formula presented]500 TeV and 2.9[Formula presented]0.3 for [Formula presented]5000 TeV with a gradual change at intermediate energies. The average mass number shows little dependence on the primary energy below 1000 TeV, with a value of 10.1[Formula presented]2.5 at 100 TeV. At higher energies the best fit average mass shows a mild increase with energy, even though no definite conclusion can be reached taking into account errors. The fitted spectra cover a range from [Formula presented] 50 TeV up to several thousand TeV. © 1997 The American Physical Society.

author list (cited authors)

  • Ambrosio, M., Antolini, R., Auriemma, G., Baker, R., Baldini, A., Barbarino, G. C., ... Webb, R.

citation count

  • 21

publication date

  • August 1997