Suppression effect of the ionization produced by electron-positron pairs of extremely high energy

Abstract

The ionizatiou produced by 27 electron-positron pairs with energies between 80 and 2000 Bev, recorded in stacks of emulsion, has been studied. The energies were estimated from the development of the soft cascades in an auxiliary experiment. Suppression of the ionization near the origin of the pairs waa obsorved, and the measured effect found to be in satisfactory agreement with theoretical predictions. The observations allow an independent estimate of the energy of the individual pair from the initial ionization, and for pairs with energy ∼300 Bev most of the values thus obtained were in good accord with those from other methods. There is a corrolation between the suppression effect and the disparity in energy of the two particles of a pair. This suggests that ionization measurements give information similar to that provided by studies of the relative seattering of the two components of a pair.