The rate of energy loss of high energy muons

Abstract

A survey is made of experimental measurements of the underground cosmic ray muon intensity, appropriate corrections being made where necessary to provide a reliable estimate of the variation of intensity with depth. An experiment has been carried out using the Durham spectrograph to obtain the effect of bias, due to accompanied particles, which was present in the published sea level spectrum of muons. These, and other experimental data, are used to derive a sea level spectrum up to 10,000 GeV. The effect of fluctuations in energy loss on the underground intensities is considered and shown to be important at depths greater than 1,000 metres water equivalent. The rate of energy loss of rauons is then derived and is found to be well represented by the equation –dE/dX = 1.88 + 0.0766 1n Em (^1)/mc (^2) + bE MeV g (^-1) cm (^2) where b takes a value (3.15 ± 0.3) x 10 (^-6) g (^-1) cm (^2). The theoretical value of b is derived and found to be 4.0 x 10 (^-6) g (^-1) cm (^2). The disagreement is thought to be due to an underestimate of the muon intensity at high energies, where the possible effect of kaons has been neglected. Finally, a revised version of the sea level spectrum of muons is derived covering the range 10 - 10,000 GeV.