The nature of the asymmetrical showers at an energy of 200 GeV and the features of the pion interaction

Abstract

The nuclear interactions of nucleons and pions at an energy of 200 GeV have been studied using an ionization calorimeter, cloud chamber, and hodoscope units. It has been found that the showers which are asymmetrical backward have the two-peak angular distribution (on a log tan θ plot) and, in the center-of-mass system, the charged particles and neutrals appear in the remote and front hemispheres respectively. The showers which are asymmetrical forward are produced mainly by primary pions and are symmetrical in the system where the target mass is close to the pion mass. It is suggested that in the cosmic-ray energy range (e.g. at energies ~10 GeV), after interaction, a pion retains a considerable part of the primary energy, but may change its charge and be transmuted into a π0 meson. Such an assumption makes it possible to explain the considerable portion of the energy transferred to a photon in the pion interactions.