Study of the nuclear and electromagnetic interactions of high-energy muons

Abstract

Cascade showers produced by high-energy cosmic muons at large zenith angles have been studied by means of an ionization calorimeter. The method of separation of electromagnetic and nuclear showers is described. The angular distribution and energy spectrum of the nuclear showers are given. An estimate of the photonuclear cross section at high energy [Formula: see text] is made using both the virtual photon spectrum developed by Weizsäcker and Williams (WW) and the theory of Kessler and Kessler (1957; KK). It is equal to (2.0 ± 1.1) × 10−28 cm2/nucleon for WW and (0.15 ± 0.08) × 10−28 cm2/nucleon for KK. The experimental electromagnetic showers with energy ~1012 eV were compared with the theoretical cascade curves. The experimental and theoretical data are in good agreement if the value of the radiation length in iron is equal to (13.8 ± 0.3) g cm−2.