Drift Velocity and DT/m Ratio for Electrons in a 0.5% Hydrogen?Xenon Mixture at 295 K

The momentum transfer cross section for electrons in xenon, am, has been studied using electron transport coefficient measurements for a dilute hydrogen-xenon mixture (0�47% H2- 99 �53% Xe). Drift velocity measurements were made using the Bradbury-Nielsen time-of-flight method at E/N values from 0 �12 to 2�50 Td, pressures from 10�3 to 94�0 kPa and a temperature of 295 K (E is the electric field strength and N the gas number density; 1 Td == 10-17 Vcm2). The ratio DT/f.t (where DT is the transverse diffusion coefficient and {� the electron mobility) was measured using a Townsend-Huxley diffusion chamber at E/N values from 0�035 to 1� 70 Td, pressures from 13�4 to 40�3 kPa, and a temperature of 294 K. Three recently published Urn values for xenon have been tested and shown to be incompatible with both the present drift velocity and DT / f.t measurements.