The ratio D T /m for electrons in a 0.5% hydrogen-krypton mixture

The ratio DT / J1. for electrons in a 0·4673% H2-99 . 5327% Kr mixture at 295 K has been measured by the Townsend-Huxley method in order to obtain data for use in the derivation of the momentum transfer cross section for krypton. The values of E/N and pressures sed ranged from 0·025 to 1· 4 Td and 13·43 to 68 ·16 kPa respectively. At a given value of E/N and pressure the derived values of DT / J1. were found to depend on the choice of the mathematical expression which relates the measured current ratio to DT/J1.. However, the values obtained using each of the expressions, when extrapolated to infinite pressure, agreed to within 0·5% for all E/N values ~0·07 Td.