Energy Required to Produce One Ion Pair in Several Noble Gases

The absolute values of $W$, the energy to produce one ion pair, for electrons have been determined for purified noble gases. A parallel plate extrapolation ionization chamber, which could be evacuated, was used. The gases investigated were ${\mathrm{H}}_2$, He, Ne, A, Kr, and Xe; and the absolute values of $W$ were 36.3; 40.3; 35.3; 25.8; 24.7; 22.0 ev respectively based on $W$ for air being 33.9 ev.