The Relativistic Increase in Ionization of High Energy Electrons and Mesotrons

Abstract

The ionization by electrons and mesotrons has been determined from drop counts along diffuse tracks that were photographed in a Wilson cloud chamber. It is believed that uncertainties in condensation efficiency and curvature do not contribute significantly to the errors. The relativistic increase in ionization for electrons agrees with theory but the average ionization of all penetrating particles is less than that predicted for a purely mesotronic composition. The minimum ionization by a singly-charged particle is 38 ion pairs per cm in dry air at N.P.T. when energy transfers greater than 600 ev are excluded.