Momentum-transfer cross section for electron-helium collisions in the range 4-12 eV

Abstract

Drift velocities of electrons in helium at 293 K have been measured in the range $2.5\ensuremath{\le}\frac{E}{N}\ensuremath{\le}7.0$ Td (1 Td = ${10}^{\ensuremath{-}17}$ V/${\mathrm{cm}}^{2}$), and analyzed to determine the momentum-transfer cross section between 4 and 12 eV. The estimated error bounds on the cross section are \ifmmode\pm\else\textpm\fi{}3% in the range $4\ensuremath{\le}\ensuremath{\epsilon}\ensuremath{\le}7$ eV and \ifmmode\pm\else\textpm\fi{}5% in the range $7<\ensuremath{\epsilon}\ensuremath{\le}12$ eV. The implications of the new result to the problem of determining standard cross sections for electron-helium scattering below the first excitation threshold are discussed.