Energy per ion pair for electrons in gases and gas mixtures

Abstract

The energy expenditure per ion pair, V , for electrons in argon, helium, hydrogen, nitrogen, air, oxygen and methane is determined using ion chambers and proportional counters with terminals which correct for ‘end-effect’. Experiments using 37 A and tritium as sources of ionizing electrons are performed. Curves of ion current against percentage of argon admixed with the other gases are plotted. The variation of V with energy of the ionizing electrons is investigated for nitrogen between the limits 200 eV and 46*7 keV for the primary electrons and only a small variation is found. The ratio V gas/ V argon is given in each case and is found to be almost identical to the corresponding ratio for ionization by 340 MeV protons. Examination of previous work with α- particles suggests close agreement with the values for electrons and protons.