Electromagnetic interactions of muons

Abstract

The electromagnetic interactions of muons in iron and lead have been studied, using cosmic ray muons, at Durham, 198 feet above sea level, and at London, 60 m.w.e. underground, respectively. The energies of the secondary particles from the interactions were determined from the cascade showers which these particles produced in layers of absorber. As a result of these studies it has been shown that, over the range of transferred energies from 0.1 GeV to 30 GeV, there is no discrepancy between- the results predicted on the basis of quantum electrodynamics and the experimental results. Since the production of knock-on electrons is the dominant process over most of this transferred energy range, there is thus no evidence for a breakdown of quantum electrodynamical theory in close collisions between muons and electrons. By combining this result with the result of an accurate measurement of the anomalous magnetic moment of the muon it is further concluded that, at the present time, there is no evidence for the muon differing from a heavy electron.