Ionization of Gases by Recoil Atoms

Abstract

The value of $W$, the average energy required to produce an ion pair, has been measured in several gases for the recoil atoms due to the alpha decay of ThC and ThC\ensuremath{'}. The method used compared proportional counter pulse heights from the first inch of alpha tracks with complete recoil tracks, auxiliary counters differentiating between the two by coincidence technique. For the recoils due to the decay of ThC, the following values of $W$ (in ev per ion pair in the indicated gas) were obtained: C${\mathrm{O}}_{2}$, 102; ${\mathrm{C}}_{3}$${\mathrm{H}}_{6}$, 99; ${\mathrm{C}}_{2}$${\mathrm{H}}_{4}$, 104; He, 60; ${\mathrm{H}}_{2}$, 81; C${\mathrm{H}}_{4}$, 111. The values for the decay of ThC\ensuremath{'} were found to be: C${\mathrm{O}}_{2}$, 99; ${\mathrm{C}}_{3}$${\mathrm{H}}_{6}$, 92; ${\mathrm{C}}_{2}$${\mathrm{H}}_{4}$, 90; He, 55; ${\mathrm{H}}_{2}$, 68; C${\mathrm{H}}_{4}$, 96.