Multiple-pion production by high-energy muons

By the use of two cloud chambers containing lead plates and iron plates, we observed 133 events of the penetrating showers produced by muons in the energy range from about 10 GeV to a few hundreds of GeV. The behaviours of the penetrating showers by muons were studied by comparing those estimated from the Heitler expression, the Kessler-Kessler expression and the DKMN expression which recently has been proposed by Daitasuet al. The crosssection for production of the showers at a depth of 50 m w.e. underground (from the top of the atmosphere) was found to be (2.58+-0.30)·10-31 cm2/nucleon for lead plates. This value leads to the photonuclear interaction cross-section αhv of (1.4+-0.25· 10-28 cm2/nucleon for the Heitler expression (1.8±0.3) · 10-29 cm2/nucleon for the K.K. expression and (3.8±0.65) · 10-29cm2/nucleon and (8.0±1.3) · 10-29 cm2/nucleon for the DKMN expressions obtained under the assumptions of a pointcharge nucleon and of a finite-size nucleon respectively. The observed energy spectrum transferred to showers and the observed distribution of the deflection angles of their muons were compared with those which were expected from various theories. By comparison, we found that the transferred energy spectrum is explained by the DKMN expression for a finite size nucleon, whereas the observed angular distribution fits the DKMN expression for a point-charge nucleon. In order to understand the results, four-dimensional momentum transfer values of showers were estimated and an existence of about 10% corelike interactions was discussed.