Electromagnetic interactions of cosmic-ray muons up to 10 TeV (pair productions and bremsstrahlung)

Abstract

Electromagnetic interactions (excluding nuclear interactions) of cosmic-ray muons were investigated by a combined arrangement of the Mutron magnet spectrometer and calorimeter. The interactions covered their transferred energies ranging from 1 GeV to several TeV produced by muons with energies up to 10 TeV. There is reasonable agreement between the experimental results and the theoretical predictions. For transferred energies less than 10 GeV, however, the observed number of events produced by muons around 1 TeV may be somewhat smaller than theoretically expected. The probability of accompaniment of a muon emerging from thick iron plates is also studied. The data are very useful for the measurement of the muon momentum by the magnet spectrometer. The ratio of the interaction probability for positive muons to that for negative muons is 0.94±0.02 for interactions with energy transfers over 1 GeV. However, by considering the measured accuracy of the value ±0.05 used for the charge ratio of incident muons, there is no evidence to support any suggestion that the interaction cross-sections of positive and negative muons for energy transfers above 1 GeV differ in the range from 100 GeV to 10 TeV.